diff --git a/doc/asio.qbk b/doc/asio.qbk
index 77f3a01e33..7b3de5adb2 100644
--- a/doc/asio.qbk
+++ b/doc/asio.qbk
@@ -20,8 +20,10 @@
 ]
 
 [template mdash[] '''— ''']
-[template indexterm1[term1] '''<indexterm><primary>'''[term1]'''</primary></indexterm>''']
-[template indexterm2[term1 term2] '''<indexterm><primary>'''[term1]'''</primary><secondary>'''[term2]'''</secondary></indexterm>''']
+[template half_open_range[text] '''&#91;'''[text])]
+[template indexterm1[id term1] '''<indexterm id="'''[id]'''"><primary>'''[term1]'''</primary></indexterm>''']
+[template indexterm2[id term1 term2] '''<indexterm id="'''[id]'''"><primary>'''[term1]'''</primary><secondary>'''[term2]'''</secondary></indexterm>''']
+[template inline_note[text] \[['Note:] [text] '''&mdash;'''['end note]\] ]
 [template ticket[number]'''<ulink url="https://svn.boost.org/trac/boost/ticket/'''[number]'''">'''#[number]'''</ulink>''']
 [def __POSIX__ /POSIX/]
 [def __Windows__ /Windows/]
@@ -31,9 +33,11 @@
 [def __getsockname__ [@http://www.opengroup.org/onlinepubs/000095399/functions/getsockname.html `getsockname()`]]
 [def __getsockopt__ [@http://www.opengroup.org/onlinepubs/000095399/functions/getsockopt.html `getsockopt()`]]
 [def __ioctl__ [@http://www.opengroup.org/onlinepubs/000095399/functions/ioctl.html `ioctl()`]]
+[def __poll__ [@http://www.opengroup.org/onlinepubs/000095399/functions/poll.html `poll()`]]
 [def __recvfrom__ [@http://www.opengroup.org/onlinepubs/000095399/functions/recvfrom.html `recvfrom()`]]
 [def __sendto__ [@http://www.opengroup.org/onlinepubs/000095399/functions/sendto.html `sendto()`]]
 [def __setsockopt__ [@http://www.opengroup.org/onlinepubs/000095399/functions/setsockopt.html `setsockopt()`]]
+[def __shutdown__ [@http://www.opengroup.org/onlinepubs/000095399/functions/shutdown.html `shutdown()`]]
 [def __socket__ [@http://www.opengroup.org/onlinepubs/000095399/functions/socket.html `socket()`]]
 
 [/=============================================================================]
diff --git a/doc/examples.qbk b/doc/examples.qbk
index de88f02cb9..fded5d8ea2 100644
--- a/doc/examples.qbk
+++ b/doc/examples.qbk
@@ -116,13 +116,13 @@ cancelling all outstanding asynchronous operations.
 
 [heading HTTP Server 2]
 
-An HTTP server using an io_service-per-CPU design.
+An HTTP server using an io_context-per-CPU design.
 
 * [@boost_asio/example/cpp03/http/server2/connection.cpp]
 * [@boost_asio/example/cpp03/http/server2/connection.hpp]
 * [@boost_asio/example/cpp03/http/server2/header.hpp]
-* [@boost_asio/example/cpp03/http/server2/io_service_pool.cpp]
-* [@boost_asio/example/cpp03/http/server2/io_service_pool.hpp]
+* [@boost_asio/example/cpp03/http/server2/io_context_pool.cpp]
+* [@boost_asio/example/cpp03/http/server2/io_context_pool.hpp]
 * [@boost_asio/example/cpp03/http/server2/main.cpp]
 * [@boost_asio/example/cpp03/http/server2/mime_types.cpp]
 * [@boost_asio/example/cpp03/http/server2/mime_types.hpp]
@@ -139,7 +139,7 @@ An HTTP server using an io_service-per-CPU design.
 
 [heading HTTP Server 3]
 
-An HTTP server using a single io_service and a thread pool calling `io_service::run()`.
+An HTTP server using a single io_context and a thread pool calling `io_context::run()`.
 
 * [@boost_asio/example/cpp03/http/server3/connection.cpp]
 * [@boost_asio/example/cpp03/http/server3/connection.hpp]
@@ -227,7 +227,7 @@ decode structures for transmission over a socket.
 [heading Services]
 
 This example demonstrates how to integrate custom functionality (in this case,
-for logging) into asio's [link boost_asio.reference.io_service io_service], and
+for logging) into asio's [link boost_asio.reference.io_context io_context], and
 how to use a custom service with [link
 boost_asio.reference.basic_stream_socket basic_stream_socket<>].
 
diff --git a/doc/overview/async.qbk b/doc/overview/async.qbk
index 37d2064be0..65eb6b4a56 100644
--- a/doc/overview/async.qbk
+++ b/doc/overview/async.qbk
@@ -30,8 +30,8 @@ read or write on a socket.]
 [mdash] Asynchronous Operation Processor
 
 [:Executes asynchronous operations and queues events on a completion event
-queue when operations complete. From a high-level point of view, services like
-`stream_socket_service` are asynchronous operation processors.]
+queue when operations complete. From a high-level point of view, internal
+services like `reactive_socket_service` are asynchronous operation processors.]
 
 [mdash] Completion Event Queue
 
@@ -52,14 +52,14 @@ a completed event to its caller.]
 
 [:Calls the asynchronous event demultiplexer to dequeue events, and dispatches
 the completion handler (i.e. invokes the function object) associated with the
-event. This abstraction is represented by the `io_service` class.]
+event. This abstraction is represented by the `io_context` class.]
 
 [mdash] Initiator
 
 [:Application-specific code that starts asynchronous operations. The initiator
 interacts with an asynchronous operation processor via a high-level interface
 such as `basic_stream_socket`, which in turn delegates to a service like
-`stream_socket_service`.]
+`reactive_socket_service`.]
 
 [heading Implementation Using Reactor]
 
@@ -97,7 +97,7 @@ calling an overlapped function such as `AcceptEx`.]
 [mdash] Completion Event Queue
 
 [:This is implemented by the operating system, and is associated with an I/O
-completion port. There is one I/O completion port for each `io_service`
+completion port. There is one I/O completion port for each `io_context`
 instance.]
 
 [mdash] Asynchronous Event Demultiplexer
diff --git a/doc/overview/basics.qbk b/doc/overview/basics.qbk
index 425462af4b..b1aa56a3d5 100644
--- a/doc/overview/basics.qbk
+++ b/doc/overview/basics.qbk
@@ -17,15 +17,15 @@ operations.
 
 [$boost_asio/sync_op.png]
 
-[*Your program] will have at least one [*io_service] object. The [*io_service]
+[*Your program] will have at least one [*io_context] object. The [*io_context]
 represents [*your program]'s link to the [*operating system]'s I/O services.
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
 To perform I/O operations [*your program] will need an [*I/O object] such as a
 TCP socket:
 
-  boost::asio::ip::tcp::socket socket(io_service);
+  boost::asio::ip::tcp::socket socket(io_context);
 
 When a synchronous connect operation is performed, the following sequence of
 events occurs:
@@ -35,15 +35,15 @@ object]:
 
   socket.connect(server_endpoint);
 
-2. The [*I/O object] forwards the request to the [*io_service].
+2. The [*I/O object] forwards the request to the [*io_context].
 
-3. The [*io_service] calls on the [*operating system] to perform the connect
+3. The [*io_context] calls on the [*operating system] to perform the connect
 operation.
 
 4. The [*operating system] returns the result of the operation to the
-[*io_service].
+[*io_context].
 
-5. The [*io_service] translates any error resulting from the operation into an
+5. The [*io_context] translates any error resulting from the operation into an
 object of type `boost::system::error_code`. An `error_code` may be compared with
 specific values, or tested as a boolean (where a `false` result means that no
 error occurred). The result is then forwarded back up to the [*I/O object].
@@ -76,9 +76,9 @@ The exact signature required depends on the asynchronous operation being
 performed. The reference documentation indicates the appropriate form for each
 operation.
 
-2. The [*I/O object] forwards the request to the [*io_service].
+2. The [*I/O object] forwards the request to the [*io_context].
 
-3. The [*io_service] signals to the [*operating system] that it should start an
+3. The [*io_context] signals to the [*operating system] that it should start an
 asynchronous connect.
 
 Time passes. (In the synchronous case this wait would have been contained
@@ -87,15 +87,15 @@ entirely within the duration of the connect operation.)
 [$boost_asio/async_op2.png]
 
 4. The [*operating system] indicates that the connect operation has completed
-by placing the result on a queue, ready to be picked up by the [*io_service].
+by placing the result on a queue, ready to be picked up by the [*io_context].
 
-5. [*Your program] must make a call to `io_service::run()` (or to one of the
-similar [*io_service] member functions) in order for the result to be
-retrieved. A call to `io_service::run()` blocks while there are unfinished
+5. [*Your program] must make a call to `io_context::run()` (or to one of the
+similar [*io_context] member functions) in order for the result to be
+retrieved. A call to `io_context::run()` blocks while there are unfinished
 asynchronous operations, so you would typically call it as soon as you have
 started your first asynchronous operation.
 
-6. While inside the call to `io_service::run()`, the [*io_service] dequeues the
+6. While inside the call to `io_context::run()`, the [*io_context] dequeues the
 result of the operation, translates it into an `error_code`, and then passes it
 to [*your completion handler].
 
diff --git a/doc/overview/bsd_sockets.qbk b/doc/overview/bsd_sockets.qbk
index f1b4e3d6de..a7a5e97210 100644
--- a/doc/overview/bsd_sockets.qbk
+++ b/doc/overview/bsd_sockets.qbk
@@ -166,10 +166,10 @@ The following table shows the mapping between the BSD socket API and Boost.Asio:
     [`poll()`,
      `select()`,
      `pselect()`]
-    [          [link boost_asio.reference.io_service.run io_service::run()],
-               [link boost_asio.reference.io_service.run_one io_service::run_one()],
-               [link boost_asio.reference.io_service.poll io_service::poll()],
-               [link boost_asio.reference.io_service.poll_one io_service::poll_one()]
+    [          [link boost_asio.reference.io_context.run io_context::run()],
+               [link boost_asio.reference.io_context.run_one io_context::run_one()],
+               [link boost_asio.reference.io_context.poll io_context::poll()],
+               [link boost_asio.reference.io_context.poll_one io_context::poll_one()]
 
       Note: in conjunction with asynchronous operations. ]
   ]
diff --git a/doc/overview/buffers.qbk b/doc/overview/buffers.qbk
index b94795ccc9..94fb5f2634 100644
--- a/doc/overview/buffers.qbk
+++ b/doc/overview/buffers.qbk
@@ -45,7 +45,7 @@ an opaque representation of contiguous memory, where:
   mechanisms for automatically determining the size of a buffer from an array,
   `boost::array` or `std::vector` of POD elements, or from a `std::string`.
 
-* Type safety violations must be explicitly requested using the `buffer_cast`
+* The underlying memory is explicitly accessed using the `data()` member
   function. In general an application should never need to do this, but it is
   required by the library implementation to pass the raw memory to the
   underlying operating system functions.
diff --git a/doc/overview/cpp2011.qbk b/doc/overview/cpp2011.qbk
index 2758236ca6..aa2e55cf6e 100644
--- a/doc/overview/cpp2011.qbk
+++ b/doc/overview/cpp2011.qbk
@@ -33,7 +33,7 @@ Windows handles.
 
 Move support allows you to write code like:
 
-  tcp::socket make_socket(io_service& i)
+  tcp::socket make_socket(io_context& i)
   {
     tcp::socket s(i);
     ...
diff --git a/doc/overview/handler_tracking.qbk b/doc/overview/handler_tracking.qbk
index 7c5f1586d2..07f6f7d0e4 100644
--- a/doc/overview/handler_tracking.qbk
+++ b/doc/overview/handler_tracking.qbk
@@ -67,7 +67,7 @@ The `<action>` takes one of the following forms:
     [~n]
     [The handler number `n` was destroyed without having been invoked. This is
     usually the case for any unfinished asynchronous operations when the
-    `io_service` is destroyed.]
+    `io_context` is destroyed.]
   ]
   [
     [n*m]
diff --git a/doc/overview/implementation.qbk b/doc/overview/implementation.qbk
index 0f4b07c7f2..0308e1ce70 100644
--- a/doc/overview/implementation.qbk
+++ b/doc/overview/implementation.qbk
@@ -22,10 +22,10 @@ descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
 Threads:
 
 * Demultiplexing using `select` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -42,10 +42,10 @@ Demultiplexing mechanism:
 Threads:
 
 * Demultiplexing using `epoll` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -63,10 +63,10 @@ Demultiplexing mechanism:
 Threads:
 
 * Demultiplexing using [^/dev/poll] is performed in one of the threads that
-calls `io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+calls `io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -85,10 +85,10 @@ descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
 Threads:
 
 * Demultiplexing using `select` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -106,10 +106,10 @@ Demultiplexing mechanism:
 Threads:
 
 * Demultiplexing using `kqueue` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -127,10 +127,10 @@ Demultiplexing mechanism:
 Threads:
 
 * Demultiplexing using `kqueue` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -149,10 +149,10 @@ descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
 Threads:
 
 * Demultiplexing using `select` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -171,10 +171,10 @@ descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
 Threads:
 
 * Demultiplexing using `select` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -193,10 +193,10 @@ descriptors in the process cannot be permitted to exceed `FD_SETSIZE`.
 Threads:
 
 * Demultiplexing using `select` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -214,10 +214,10 @@ Demultiplexing mechanism:
 Threads:
 
 * Demultiplexing using `select` is performed in one of the threads that calls
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -238,17 +238,17 @@ operations except for asynchronous connect.
 Threads:
 
 * Demultiplexing using I/O completion ports is performed in all threads that call
-`io_service::run()`, `io_service::run_one()`, `io_service::poll()` or
-`io_service::poll_one()`.
+`io_context::run()`, `io_context::run_one()`, `io_context::poll()` or
+`io_context::poll_one()`.
 
-* An additional thread per `io_service` is used to trigger timers. This thread
-is created on construction of the first `deadline_timer` or
-`deadline_timer_service` objects.
+* An additional thread per `io_context` is used to trigger timers. This thread
+is created on construction of the first `basic_deadline_timer` or
+`basic_waitable_timer` objects.
 
-* An additional thread per `io_service` is used for the `select`
+* An additional thread per `io_context` is used for the `select`
 demultiplexing. This thread is created on the first call to `async_connect()`.
 
-* An additional thread per `io_service` is used to emulate asynchronous host
+* An additional thread per `io_context` is used to emulate asynchronous host
 resolution. This thread is created on the first call to either
 `ip::tcp::resolver::async_resolve()` or `ip::udp::resolver::async_resolve()`.
 
@@ -265,7 +265,7 @@ Boost.Asio provides limited support for the Windows Runtime. It requires that th
 language extensions be enabled. Due to the restricted facilities exposed by the
 Windows Runtime API, the support comes with the following caveats:
 
-* The core facilities such as the `io_service`, `strand`, buffers, composed
+* The core facilities such as the `io_context`, `strand`, buffers, composed
   operations, timers, etc., should all work as normal.
 
 * For sockets, only client-side TCP is supported.
@@ -292,9 +292,9 @@ Demultiplexing mechanism:
 Threads:
 
 * Event completions are delivered to the Windows thread pool and posted to the
-  `io_service` for the handler to be executed.
+  `io_context` for the handler to be executed.
 
-* An additional thread per `io_service` is used to trigger timers. This thread
+* An additional thread per `io_context` is used to trigger timers. This thread
   is created on construction of the first timer objects.
 
 Scatter-Gather:
diff --git a/doc/overview/iostreams.qbk b/doc/overview/iostreams.qbk
index 3e9b7f1430..2f0995a0d5 100644
--- a/doc/overview/iostreams.qbk
+++ b/doc/overview/iostreams.qbk
@@ -20,7 +20,7 @@ independence, etc. To create a connection one might simply write:
 The iostream class can also be used in conjunction with an acceptor to create
 simple servers. For example:
 
-  io_service ios;
+  io_context ioc;
 
   ip::tcp::endpoint endpoint(tcp::v4(), 80);
   ip::tcp::acceptor acceptor(ios, endpoint);
@@ -28,7 +28,7 @@ simple servers. For example:
   for (;;)
   {
     ip::tcp::iostream stream;
-    acceptor.accept(*stream.rdbuf());
+    acceptor.accept(stream.socket());
     ...
   }
 
diff --git a/doc/overview/other_protocols.qbk b/doc/overview/other_protocols.qbk
index 42fec45d4a..aa69e564d8 100644
--- a/doc/overview/other_protocols.qbk
+++ b/doc/overview/other_protocols.qbk
@@ -22,7 +22,7 @@ These classes implement the [link boost_asio.reference.Protocol protocol type
 requirements], but allow the user to specify the address family (e.g. `AF_INET`)
 and protocol type (e.g. `IPPROTO_TCP`) at runtime. For example:
 
-  boost::asio::generic::stream_protocol::socket my_socket(my_io_service);
+  boost::asio::generic::stream_protocol::socket my_socket(my_io_context);
   my_socket.open(boost::asio::generic::stream_protocol(AF_INET, IPPROTO_TCP));
   ...
 
@@ -38,7 +38,7 @@ endpoint] type requirements:
 
 The conversion is implicit, so as to support the following use cases:
 
-  boost::asio::generic::stream_protocol::socket my_socket(my_io_service);
+  boost::asio::generic::stream_protocol::socket my_socket(my_io_context);
   boost::asio::ip::tcp::endpoint my_endpoint = ...;
   my_socket.connect(my_endpoint);
 
@@ -53,14 +53,14 @@ type. If the protocol conversion is valid:
 
 then the corresponding socket conversion is allowed:
 
-  Protocol1::socket my_socket1(my_io_service);
+  Protocol1::socket my_socket1(my_io_context);
   ...
   Protocol2::socket my_socket2(std::move(my_socket1));
 
 For example, one possible conversion is from a TCP socket to a generic
 stream-oriented socket:
 
-  boost::asio::ip::tcp::socket my_socket1(my_io_service);
+  boost::asio::ip::tcp::socket my_socket1(my_io_context);
   ...
   boost::asio::generic::stream_protocol::socket my_socket2(std::move(my_socket1));
 
@@ -78,9 +78,9 @@ corresponding protocol conversion is valid. For example, the following is
 supported because the protocol `boost::asio::ip::tcp` is convertible to
 `boost::asio::generic::stream_protocol`:
 
-  boost::asio::ip::tcp::acceptor my_acceptor(my_io_service);
+  boost::asio::ip::tcp::acceptor my_acceptor(my_io_context);
   ...
-  boost::asio::generic::stream_protocol::socket my_socket(my_io_service);
+  boost::asio::generic::stream_protocol::socket my_socket(my_io_context);
   my_acceptor.accept(my_socket);
 
 [heading See Also]
diff --git a/doc/overview/posix.qbk b/doc/overview/posix.qbk
index d7468ea8b4..8fba83bd96 100644
--- a/doc/overview/posix.qbk
+++ b/doc/overview/posix.qbk
@@ -19,15 +19,15 @@ Boost.Asio provides basic support UNIX domain sockets (also known as local socke
 The simplest use involves creating a pair of connected sockets. The following
 code:
 
-  local::stream_protocol::socket socket1(my_io_service);
-  local::stream_protocol::socket socket2(my_io_service);
+  local::stream_protocol::socket socket1(my_io_context);
+  local::stream_protocol::socket socket2(my_io_context);
   local::connect_pair(socket1, socket2);
 
 will create a pair of stream-oriented sockets. To do the same for
 datagram-oriented sockets, use:
 
-  local::datagram_protocol::socket socket1(my_io_service);
-  local::datagram_protocol::socket socket2(my_io_service);
+  local::datagram_protocol::socket socket1(my_io_context);
+  local::datagram_protocol::socket socket2(my_io_context);
   local::connect_pair(socket1, socket2);
 
 A UNIX domain socket server may be created by binding an acceptor to an
@@ -35,14 +35,14 @@ endpoint, in much the same way as one does for a TCP server:
 
   ::unlink("/tmp/foobar"); // Remove previous binding.
   local::stream_protocol::endpoint ep("/tmp/foobar");
-  local::stream_protocol::acceptor acceptor(my_io_service, ep);
-  local::stream_protocol::socket socket(my_io_service);
+  local::stream_protocol::acceptor acceptor(my_io_context, ep);
+  local::stream_protocol::socket socket(my_io_context);
   acceptor.accept(socket);
 
 A client that connects to this server might look like:
 
   local::stream_protocol::endpoint ep("/tmp/foobar");
-  local::stream_protocol::socket socket(my_io_service);
+  local::stream_protocol::socket socket(my_io_context);
   socket.connect(ep);
 
 Transmission of file descriptors or credentials across UNIX domain sockets is
@@ -88,8 +88,8 @@ performed immediately. Wait operations, and operations involving
 For example, to perform read and write operations on standard input
 and output, the following objects may be created:
 
-  posix::stream_descriptor in(my_io_service, ::dup(STDIN_FILENO));
-  posix::stream_descriptor out(my_io_service, ::dup(STDOUT_FILENO));
+  posix::stream_descriptor in(my_io_context, ::dup(STDIN_FILENO));
+  posix::stream_descriptor out(my_io_context, ::dup(STDOUT_FILENO));
 
 These are then used as synchronous or asynchronous read and write streams. This
 means the objects can be used with any of the [link boost_asio.reference.read
@@ -101,8 +101,6 @@ boost_asio.reference.async_read_until async_read_until()] free functions.
 [heading See Also]
 
 [link boost_asio.reference.posix__stream_descriptor posix::stream_descriptor],
-[link boost_asio.reference.posix__basic_stream_descriptor posix::basic_stream_descriptor],
-[link boost_asio.reference.posix__stream_descriptor_service posix::stream_descriptor_service],
 [link boost_asio.examples.cpp03_examples.chat Chat example (C++03)],
 [link boost_asio.examples.cpp11_examples.chat Chat example (C++11)].
 
@@ -117,25 +115,25 @@ target operating system. A program may test for the macro
 [section:fork Fork]
 
 Boost.Asio supports programs that utilise the `fork()` system call. Provided the
-program calls `io_service.notify_fork()` at the appropriate times, Boost.Asio will
+program calls `io_context.notify_fork()` at the appropriate times, Boost.Asio will
 recreate any internal file descriptors (such as the "self-pipe trick"
 descriptor used for waking up a reactor). The notification is usually performed
 as follows:
 
-  io_service_.notify_fork(boost::asio::io_service::fork_prepare);
+  io_context_.notify_fork(boost::asio::io_context::fork_prepare);
   if (fork() == 0)
   {
-    io_service_.notify_fork(boost::asio::io_service::fork_child);
+    io_context_.notify_fork(boost::asio::io_context::fork_child);
     ...
   }
   else
   {
-    io_service_.notify_fork(boost::asio::io_service::fork_parent);
+    io_context_.notify_fork(boost::asio::io_context::fork_parent);
     ...
   }
 
 User-defined services can also be made fork-aware by overriding the
-`io_service::service::fork_service()` virtual function.
+`io_context::service::notify_fork()` virtual function.
 
 Note that any file descriptors accessible via Boost.Asio's public API (e.g. the
 descriptors underlying `basic_socket<>`, `posix::stream_descriptor`, etc.) are
@@ -144,9 +142,9 @@ as required.
 
 [heading See Also]
 
-[link boost_asio.reference.io_service.notify_fork io_service::notify_fork()],
-[link boost_asio.reference.io_service.fork_event io_service::fork_event],
-[link boost_asio.reference.io_service__service.fork_service io_service::service::fork_service()],
+[link boost_asio.reference.io_context.notify_fork io_context::notify_fork()],
+[link boost_asio.reference.io_context.fork_event io_context::fork_event],
+[link boost_asio.reference.execution_context__service.notify_fork io_context::service::notify_fork()],
 [link boost_asio.examples.cpp03_examples.fork Fork examples].
 
 [endsect]
diff --git a/doc/overview/protocols.qbk b/doc/overview/protocols.qbk
index 65895ff70e..6b0b61bf63 100644
--- a/doc/overview/protocols.qbk
+++ b/doc/overview/protocols.qbk
@@ -15,7 +15,7 @@ ICMP.
 Hostname resolution is performed using a resolver, where host and service names
 are looked up and converted into one or more endpoints:
 
-  ip::tcp::resolver resolver(my_io_service);
+  ip::tcp::resolver resolver(my_io_context);
   ip::tcp::resolver::query query("www.boost.org", "http");
   ip::tcp::resolver::iterator iter = resolver.resolve(query);
   ip::tcp::resolver::iterator end; // End marker.
@@ -35,7 +35,7 @@ connect()] and [link boost_asio.reference.async_connect async_connect()]. These
 operations try each endpoint in a list until the socket is successfully
 connected. For example, a single call:
 
-  ip::tcp::socket socket(my_io_service);
+  ip::tcp::socket socket(my_io_context);
   boost::asio::connect(socket, resolver.resolve(query));
 
 will synchronously try all endpoints until one is successfully connected.
@@ -61,7 +61,7 @@ Similarly, an asynchronous connect may be performed by writing:
 
 When a specific endpoint is available, a socket can be created and connected:
 
-  ip::tcp::socket socket(my_io_service);
+  ip::tcp::socket socket(my_io_context);
   socket.connect(endpoint);
 
 Data may be read from or written to a connected TCP socket using the [link
@@ -79,9 +79,9 @@ boost_asio.reference.async_write async_write()].
 
 A program uses an acceptor to accept incoming TCP connections:
 
-  ip::tcp::acceptor acceptor(my_io_service, my_endpoint);
+  ip::tcp::acceptor acceptor(my_io_context, my_endpoint);
   ...
-  ip::tcp::socket socket(my_io_service);
+  ip::tcp::socket socket(my_io_context);
   acceptor.accept(socket);
 
 After a socket has been successfully accepted, it may be read from or written
@@ -91,7 +91,7 @@ to as illustrated for TCP clients above.
 
 UDP hostname resolution is also performed using a resolver:
 
-  ip::udp::resolver resolver(my_io_service);
+  ip::udp::resolver resolver(my_io_context);
   ip::udp::resolver::query query("localhost", "daytime");
   ip::udp::resolver::iterator iter = resolver.resolve(query);
   ...
@@ -101,7 +101,7 @@ create an IP version 4 UDP socket and bind it to the "any" address on port
 `12345`:
 
   ip::udp::endpoint endpoint(ip::udp::v4(), 12345);
-  ip::udp::socket socket(my_io_service, endpoint);
+  ip::udp::socket socket(my_io_context, endpoint);
 
 Data may be read from or written to an unconnected UDP socket using the [link
 boost_asio.reference.basic_datagram_socket.receive_from receive_from()], [link
@@ -118,7 +118,7 @@ boost_asio.reference.basic_datagram_socket.async_send async_send()] member funct
 
 As with TCP and UDP, ICMP hostname resolution is performed using a resolver:
 
-  ip::icmp::resolver resolver(my_io_service);
+  ip::icmp::resolver resolver(my_io_context);
   ip::icmp::resolver::query query("localhost", "");
   ip::icmp::resolver::iterator iter = resolver.resolve(query);
   ...
@@ -127,7 +127,7 @@ An ICMP socket may be bound to a local endpoint. The following code will create
 an IP version 6 ICMP socket and bind it to the "any" address:
 
   ip::icmp::endpoint endpoint(ip::icmp::v6(), 0);
-  ip::icmp::socket socket(my_io_service, endpoint);
+  ip::icmp::socket socket(my_io_context, endpoint);
 
 The port number is not used for ICMP.
 
diff --git a/doc/overview/reactor.qbk b/doc/overview/reactor.qbk
index bc36a9c24a..ad405f688b 100644
--- a/doc/overview/reactor.qbk
+++ b/doc/overview/reactor.qbk
@@ -8,19 +8,18 @@
 [section:reactor Reactor-Style Operations]
 
 Sometimes a program must be integrated with a third-party library that wants to
-perform the I/O operations itself. To facilitate this, Boost.Asio includes a
-`null_buffers` type that can be used with both read and write operations. A
-`null_buffers` operation doesn't return until the I/O object is "ready" to
-perform the operation.
+perform the I/O operations itself. To facilitate this, Boost.Asio includes
+synchronous and asynchronous operations that may be used to wait for a socket
+to become ready to read, ready to write, or to have a pending error condition.
 
-As an example, to perform a non-blocking read something like the
-following may be used:
+As an example, to perform a non-blocking read something like the following may
+be used:
 
-  ip::tcp::socket socket(my_io_service);
+  ip::tcp::socket socket(my_io_context);
   ...
   socket.non_blocking(true);
   ...
-  socket.async_read_some(null_buffers(), read_handler);
+  socket.async_wait(ip::tcp::socket::wait_read, read_handler);
   ...
   void read_handler(boost::system::error_code ec)
   {
@@ -36,7 +35,8 @@ stream-oriented descriptor classes.
 
 [heading See Also]
 
-[link boost_asio.reference.null_buffers null_buffers],
+[link boost_asio.reference.basic_socket.wait basic_socket::wait()],
+[link boost_asio.reference.basic_socket.async_wait basic_socket::async_wait()],
 [link boost_asio.reference.basic_socket.non_blocking basic_socket::non_blocking()],
 [link boost_asio.reference.basic_socket.native_non_blocking basic_socket::native_non_blocking()],
 [link boost_asio.examples.cpp03_examples.nonblocking nonblocking example].
diff --git a/doc/overview/serial_ports.qbk b/doc/overview/serial_ports.qbk
index 2a8bc07a08..e3edef37c1 100644
--- a/doc/overview/serial_ports.qbk
+++ b/doc/overview/serial_ports.qbk
@@ -10,7 +10,7 @@
 Boost.Asio includes classes for creating and manipulating serial ports in a portable
 manner. For example, a serial port may be opened using:
 
-  serial_port port(my_io_service, name);
+  serial_port port(my_io_context, name);
 
 where name is something like `"COM1"` on Windows, and `"/dev/ttyS0"` on POSIX
 platforms.
@@ -29,8 +29,6 @@ port's baud rate, flow control type, parity, stop bits and character size.
 
 [link boost_asio.reference.serial_port serial_port],
 [link boost_asio.reference.serial_port_base serial_port_base],
-[link boost_asio.reference.basic_serial_port basic_serial_port],
-[link boost_asio.reference.serial_port_service serial_port_service],
 [link boost_asio.reference.serial_port_base__baud_rate serial_port_base::baud_rate],
 [link boost_asio.reference.serial_port_base__flow_control serial_port_base::flow_control],
 [link boost_asio.reference.serial_port_base__parity serial_port_base::parity],
diff --git a/doc/overview/signals.qbk b/doc/overview/signals.qbk
index 1eb02f985e..8b83782a11 100644
--- a/doc/overview/signals.qbk
+++ b/doc/overview/signals.qbk
@@ -27,7 +27,7 @@ however the signal number must be used only with Boost.Asio.
   ...
 
   // Construct a signal set registered for process termination.
-  boost::asio::signal_set signals(io_service, SIGINT, SIGTERM);
+  boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
 
   // Start an asynchronous wait for one of the signals to occur.
   signals.async_wait(handler);
diff --git a/doc/overview/spawn.qbk b/doc/overview/spawn.qbk
index bea7b02820..03d917e5b9 100644
--- a/doc/overview/spawn.qbk
+++ b/doc/overview/spawn.qbk
@@ -38,8 +38,8 @@ synchronous manner, as shown in the following example:
   }
 
 The first argument to `spawn()` may be a
-[link boost_asio.reference.io_service__strand `strand`],
-[link boost_asio.reference.io_service `io_service`], or
+[link boost_asio.reference.io_context__strand `strand`],
+[link boost_asio.reference.io_context `io_context`], or
 [link boost_asio.reference.CompletionHandler completion handler].
 This argument determines the context in which the coroutine is permitted to
 execute. For example, a server's per-client object may consist of multiple
diff --git a/doc/overview/ssl.qbk b/doc/overview/ssl.qbk
index 693a07908e..529af15db4 100644
--- a/doc/overview/ssl.qbk
+++ b/doc/overview/ssl.qbk
@@ -22,7 +22,7 @@ initialisation may look something like:
 
 To use SSL with a TCP socket, one may write:
 
-  ssl::stream<ip::tcp::socket> ssl_sock(my_io_service, ctx);
+  ssl::stream<ip::tcp::socket> ssl_sock(my_io_context, ctx);
 
 To perform socket-specific operations, such as establishing an outbound
 connection or accepting an incoming one, the underlying socket must first be
@@ -36,7 +36,7 @@ In some use cases the underlying stream object will need to have a longer
 lifetime than the SSL stream, in which case the template parameter should be a
 reference to the stream type:
 
-  ip::tcp::socket sock(my_io_service);
+  ip::tcp::socket sock(my_io_context);
   ssl::stream<ip::tcp::socket&> ssl_sock(sock, ctx);
 
 SSL handshaking must be performed prior to transmitting or receiving data over
@@ -82,9 +82,9 @@ according to the rules used by HTTPS:
   ctx.set_default_verify_paths();
 
   // Open a socket and connect it to the remote host.
-  boost::asio::io_service io_service;
-  ssl_socket sock(io_service, ctx);
-  tcp::resolver resolver(io_service);
+  boost::asio::io_context io_context;
+  ssl_socket sock(io_context, ctx);
+  tcp::resolver resolver(io_context);
   tcp::resolver::query query("host.name", "https");
   boost::asio::connect(sock.lowest_layer(), resolver.resolve(query));
   sock.lowest_layer().set_option(tcp::no_delay(true));
diff --git a/doc/overview/strands.qbk b/doc/overview/strands.qbk
index 7f9bd243d3..16bb04efb4 100644
--- a/doc/overview/strands.qbk
+++ b/doc/overview/strands.qbk
@@ -15,8 +15,8 @@ mutexes).
 Strands may be either implicit or explicit, as illustrated by the following
 alternative approaches:
 
-* Calling io_service::run() from only one thread means all event handlers
-  execute in an implicit strand, due to the io_service's guarantee that handlers
+* Calling io_context::run() from only one thread means all event handlers
+  execute in an implicit strand, due to the io_context's guarantee that handlers
   are only invoked from inside run().
 
 * Where there is a single chain of asynchronous operations associated with a
@@ -24,38 +24,61 @@ alternative approaches:
   no possibility of concurrent execution of the handlers. This is an implicit
   strand.
 
-* An explicit strand is an instance of `io_service::strand`. All event handler
-  function objects need to be wrapped using `io_service::strand::wrap()` or
-  otherwise posted/dispatched through the `io_service::strand` object.
+* An explicit strand is an instance of `strand<>` or `io_context::strand`. All
+  event handler function objects need to be bound to the strand using
+  `boost::asio::bind_executor()` or otherwise posted/dispatched through the strand
+  object.
 
 In the case of composed asynchronous operations, such as `async_read()` or
 `async_read_until()`, if a completion handler goes through a strand, then all
 intermediate handlers should also go through the same strand. This is needed to
 ensure thread safe access for any objects that are shared between the caller
 and the composed operation (in the case of `async_read()` it's the socket,
-which the caller can close() to cancel the operation). This is done by having
-hook functions for all intermediate handlers which forward the calls to the
-customisable hook associated with the final handler:
+which the caller can `close()` to cancel the operation).
+
+This is done by partially specialising the `boost::asio::ssociated_executor<>` trait
+for all intermediate handlers. This trait forwards to the corresponding trait
+specialisation for the final handler:
 
   struct my_handler
   {
     void operator()() { ... }
   };
 
-  template<class F>
-  void asio_handler_invoke(F f, my_handler*)
-  {
-    // Do custom invocation here.
-    // Default implementation calls f();
-  }
+  namespace boost { namespace asio {
+
+    template <class Executor>
+    struct associated_executor<my_handler, Executor>
+    {
+      // Custom implementation of Executor type requirements.
+      typedef my_executor type;
+
+      // Return a custom executor implementation.
+      static type get(const my_handler&, const Executor& = Executor())
+      {
+        return my_executor();
+      }
+    };
+
+  } } // namespace boost::asio
+
+The `boost::asio::bind_executor()` function is a helper to bind a specific executor
+object, such as a strand, to a completion handler. This binding automatically
+specialises the `associated_executor` trait as shown above. For example, to
+bind a strand to a completion handler we would simply write:
 
-The `io_service::strand::wrap()` function creates a new completion handler that
-defines `asio_handler_invoke` so that the function object is executed through
-the strand.
+  my_socket.async_read_some(my_buffer,
+      boost::asio::bind_executor(my_strand,
+        [](error_code ec, size_t length)
+        {
+          // ...
+        }));
 
 [heading See Also]
 
-[link boost_asio.reference.io_service__strand io_service::strand],
+[link boost_asio.reference.bind_executor bind_executor],
+[link boost_asio.reference.strand strand],
+[link boost_asio.reference.io_context__strand io_context::strand],
 [link boost_asio.tutorial.tuttimer5 tutorial Timer.5],
 [link boost_asio.examples.cpp03_examples.http_server_3 HTTP server 3 example].
 
diff --git a/doc/overview/threads.qbk b/doc/overview/threads.qbk
index 23839a043d..7543676afc 100644
--- a/doc/overview/threads.qbk
+++ b/doc/overview/threads.qbk
@@ -10,19 +10,19 @@
 [heading Thread Safety]
 
 In general, it is safe to make concurrent use of distinct objects, but unsafe
-to make concurrent use of a single object. However, types such as `io_service`
+to make concurrent use of a single object. However, types such as `io_context`
 provide a stronger guarantee that it is safe to use a single object
 concurrently.
 
 [heading Thread Pools]
 
-Multiple threads may call `io_service::run()` to set up a pool of threads from
+Multiple threads may call `io_context::run()` to set up a pool of threads from
 which completion handlers may be invoked. This approach may also be used with
-`io_service::post()` to use a means to perform any computational tasks across a
+`io_context::post()` to use a means to perform any computational tasks across a
 thread pool.
 
-Note that all threads that have joined an `io_service`'s pool are considered
-equivalent, and the `io_service` may distribute work across them in an
+Note that all threads that have joined an `io_context`'s pool are considered
+equivalent, and the `io_context` may distribute work across them in an
 arbitrary fashion.
 
 [heading Internal Threads]
@@ -38,14 +38,14 @@ these threads must be invisible to the library user. In particular, the threads:
 This approach is complemented by the following guarantee:
 
 * Asynchronous completion handlers will only be called from threads that are
-  currently calling `io_service::run()`.
+  currently calling `io_context::run()`.
 
 Consequently, it is the library user's responsibility to create and manage all
 threads to which the notifications will be delivered.
 
 The reasons for this approach include:
 
-* By only calling `io_service::run()` from a single thread, the user's code can
+* By only calling `io_context::run()` from a single thread, the user's code can
   avoid the development complexity associated with synchronisation. For
   example, a library user can implement scalable servers that are
   single-threaded (from the user's point of view).
@@ -61,6 +61,6 @@ The reasons for this approach include:
 
 [heading See Also]
 
-[link boost_asio.reference.io_service io_service].
+[link boost_asio.reference.io_context io_context].
 
 [endsect]
diff --git a/doc/overview/timers.qbk b/doc/overview/timers.qbk
index ec22a54dfa..50fd76d4d4 100644
--- a/doc/overview/timers.qbk
+++ b/doc/overview/timers.qbk
@@ -14,7 +14,7 @@ calculated relative to the current time.
 As a simple example, to perform a synchronous wait operation on a timer using a
 relative time one may write:
 
-  io_service i;
+  io_context i;
   ...
   deadline_timer t(i);
   t.expires_from_now(boost::posix_time::seconds(5));
@@ -25,7 +25,7 @@ timer:
 
   void handler(boost::system::error_code ec) { ... }
   ...
-  io_service i;
+  io_context i;
   ...
   deadline_timer t(i);
   t.expires_from_now(boost::posix_time::milliseconds(400));
@@ -47,7 +47,6 @@ or as an absolute time to allow composition of timers:
 
 [link boost_asio.reference.basic_deadline_timer basic_deadline_timer],
 [link boost_asio.reference.deadline_timer deadline_timer],
-[link boost_asio.reference.deadline_timer_service deadline_timer_service],
 [link boost_asio.tutorial.tuttimer1 timer tutorials].
 
 [endsect]
diff --git a/doc/overview/windows.qbk b/doc/overview/windows.qbk
index eba696fdd5..26c1111e03 100644
--- a/doc/overview/windows.qbk
+++ b/doc/overview/windows.qbk
@@ -22,7 +22,7 @@ For example, to perform asynchronous operations on a named pipe, the following
 object may be created:
 
   HANDLE handle = ::CreateFile(...);
-  windows::stream_handle pipe(my_io_service, handle);
+  windows::stream_handle pipe(my_io_context, handle);
 
 These are then used as synchronous or asynchronous read and write streams. This
 means the objects can be used with any of the [link boost_asio.reference.read
@@ -37,9 +37,7 @@ pipes and console streams are not).
 
 [heading See Also]
 
-[link boost_asio.reference.windows__stream_handle windows::stream_handle],
-[link boost_asio.reference.windows__basic_stream_handle windows::basic_stream_handle],
-[link boost_asio.reference.windows__stream_handle_service windows::stream_handle_service].
+[link boost_asio.reference.windows__stream_handle windows::stream_handle].
 
 [heading Notes]
 
@@ -61,7 +59,7 @@ For example, to perform asynchronous operations on a file the following object
 may be created:
 
   HANDLE handle = ::CreateFile(...);
-  windows::random_access_handle file(my_io_service, handle);
+  windows::random_access_handle file(my_io_context, handle);
 
 Data may be read from or written to the handle using one of the
 `read_some_at()`, `async_read_some_at()`, `write_some_at()` or
@@ -76,9 +74,7 @@ all data has been transferred.
 
 [heading See Also]
 
-[link boost_asio.reference.windows__random_access_handle windows::random_access_handle],
-[link boost_asio.reference.windows__basic_random_access_handle windows::basic_random_access_handle],
-[link boost_asio.reference.windows__random_access_handle_service windows::random_access_handle_service].
+[link boost_asio.reference.windows__random_access_handle windows::random_access_handle].
 
 [heading Notes]
 
@@ -110,16 +106,14 @@ For example, to perform asynchronous operations on an event, the following
 object may be created:
 
   HANDLE handle = ::CreateEvent(...);
-  windows::object_handle file(my_io_service, handle);
+  windows::object_handle file(my_io_context, handle);
 
 The `wait()` and `async_wait()` member functions may then be used to wait until
 the kernel object is signalled.
 
 [heading See Also]
 
-[link boost_asio.reference.windows__object_handle windows::object_handle],
-[link boost_asio.reference.windows__basic_object_handle windows::basic_object_handle],
-[link boost_asio.reference.windows__object_handle_service windows::object_handle_service].
+[link boost_asio.reference.windows__object_handle windows::object_handle].
 
 [heading Notes]
 
diff --git a/doc/reference.xsl b/doc/reference.xsl
index 557d2e5eeb..fcabb59379 100644
--- a/doc/reference.xsl
+++ b/doc/reference.xsl
@@ -37,57 +37,51 @@
 [xinclude quickref.xml]
 
 [include requirements/asynchronous_operations.qbk]
+[include requirements/read_write_operations.qbk]
+[include requirements/synchronous_socket_operations.qbk]
+[include requirements/asynchronous_socket_operations.qbk]
+[include requirements/AcceptableProtocol.qbk]
 [include requirements/AcceptHandler.qbk]
 [include requirements/AsyncRandomAccessReadDevice.qbk]
 [include requirements/AsyncRandomAccessWriteDevice.qbk]
 [include requirements/AsyncReadStream.qbk]
 [include requirements/AsyncWriteStream.qbk]
 [include requirements/BufferedHandshakeHandler.qbk]
+[include requirements/CompletionCondition.qbk]
 [include requirements/CompletionHandler.qbk]
-[include requirements/ComposedConnectHandler.qbk]
+[include requirements/ConnectCondition.qbk]
 [include requirements/ConnectHandler.qbk]
 [include requirements/ConstBufferSequence.qbk]
-[include requirements/ConvertibleToConstBuffer.qbk]
-[include requirements/ConvertibleToMutableBuffer.qbk]
-[include requirements/DatagramSocketService.qbk]
-[include requirements/DescriptorService.qbk]
+[include requirements/DynamicBuffer.qbk]
 [include requirements/Endpoint.qbk]
+[include requirements/EndpointSequence.qbk]
+[include requirements/ExecutionContext.qbk]
+[include requirements/Executor.qbk]
 [include requirements/GettableSerialPortOption.qbk]
 [include requirements/GettableSocketOption.qbk]
 [include requirements/Handler.qbk]
-[include requirements/HandleService.qbk]
 [include requirements/HandshakeHandler.qbk]
 [include requirements/InternetProtocol.qbk]
 [include requirements/IoControlCommand.qbk]
 [include requirements/IoObjectService.qbk]
+[include requirements/IteratorConnectHandler.qbk]
+[include requirements/MoveAcceptHandler.qbk]
 [include requirements/MutableBufferSequence.qbk]
-[include requirements/ObjectHandleService.qbk]
+[include requirements/ProtoAllocator.qbk]
 [include requirements/Protocol.qbk]
-[include requirements/RandomAccessHandleService.qbk]
-[include requirements/RawSocketService.qbk]
+[include requirements/RangeConnectHandler.qbk]
 [include requirements/ReadHandler.qbk]
 [include requirements/ResolveHandler.qbk]
-[include requirements/ResolverService.qbk]
-[include requirements/SeqPacketSocketService.qbk]
-[include requirements/SerialPortService.qbk]
 [include requirements/Service.qbk]
 [include requirements/SettableSerialPortOption.qbk]
 [include requirements/SettableSocketOption.qbk]
 [include requirements/ShutdownHandler.qbk]
 [include requirements/SignalHandler.qbk]
-[include requirements/SignalSetService.qbk]
-[include requirements/SocketAcceptorService.qbk]
-[include requirements/SocketService.qbk]
-[include requirements/StreamDescriptorService.qbk]
-[include requirements/StreamHandleService.qbk]
-[include requirements/StreamSocketService.qbk]
 [include requirements/SyncRandomAccessReadDevice.qbk]
 [include requirements/SyncRandomAccessWriteDevice.qbk]
 [include requirements/SyncReadStream.qbk]
 [include requirements/SyncWriteStream.qbk]
 [include requirements/TimeTraits.qbk]
-[include requirements/TimerService.qbk]
-[include requirements/WaitableTimerService.qbk]
 [include requirements/WaitHandler.qbk]
 [include requirements/WaitTraits.qbk]
 [include requirements/WriteHandler.qbk]
@@ -105,7 +99,9 @@
             contains(compoundname, 'asio::') and
             not(contains(compoundname, '::detail')) and
             not(contains(compoundname, '::service::key')) and
-            not(contains(compoundname, '_handler'))">
+            not(contains(compoundname, '_handler')) and
+            not(contains(compoundname, 'thread_function')) and
+            not(contains(compoundname, 'context_impl'))">
           <xsl:call-template name="class"/>
         </xsl:if>
       </xsl:when>
@@ -115,7 +111,8 @@
             not(contains(ancestor::*/compoundname, '::service::key')) and
             not(contains(ancestor::*/compoundname, '_helper')) and
             not(contains(name, '_helper')) and
-            not(contains(name, 'io_service_impl'))">
+            not(contains(name, 'thread_function')) and
+            not(contains(name, 'io_context_impl'))">
           <xsl:call-template name="namespace-memberdef"/>
         </xsl:if>
       </xsl:otherwise>
@@ -194,7 +191,7 @@
   </xsl:variable>
   <xsl:choose>
     <xsl:when test="$type='void_or_deduced'">
-      <xsl:text>``[link boost_asio.reference.asynchronous_operations.return_type_of_an_initiating_function ['void-or-deduced]]``</xsl:text>
+      <xsl:text>``[link boost_asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type ['DEDUCED]]``</xsl:text>
     </xsl:when>   
     <xsl:otherwise>
       <xsl:value-of select="$type"/>
@@ -302,6 +299,18 @@
          select="concat(substring-before($name, '~'), '_', substring-after($name, '~'))"/>
       </xsl:call-template>
     </xsl:when>
+    <xsl:when test="contains($name, ',')">
+      <xsl:call-template name="make-id">
+        <xsl:with-param name="name"
+         select="concat(substring-before($name, ','), '_comma_', substring-after($name, ','))"/>
+      </xsl:call-template>
+    </xsl:when>
+    <xsl:when test="contains($name, '...')">
+      <xsl:call-template name="make-id">
+        <xsl:with-param name="name"
+         select="concat(substring-before($name, '...'), '_ellipsis_', substring-after($name, '...'))"/>
+      </xsl:call-template>
+    </xsl:when>
     <xsl:when test="contains($name, ' ')">
       <xsl:call-template name="make-id">
         <xsl:with-param name="name"
@@ -595,6 +604,13 @@
         <xsl:with-param name="text" select="substring-after($text, ']')"/>
       </xsl:call-template>
     </xsl:when>
+    <xsl:when test="contains($text, '...')">
+      <xsl:value-of select="substring-before($text, '...')"/>
+      <xsl:text>\.\.\.</xsl:text>
+      <xsl:call-template name="escape-name">
+        <xsl:with-param name="text" select="substring-after($text, '...')"/>
+      </xsl:call-template>
+    </xsl:when>
     <xsl:otherwise>
       <xsl:value-of select="$text"/>
     </xsl:otherwise>
@@ -752,6 +768,9 @@
     <xsl:when test="contains($file, 'boost/asio/high_resolution_timer')">
       <xsl:text>None</xsl:text>
     </xsl:when>
+    <xsl:when test="contains($file, 'boost/asio/package')">
+      <xsl:text>None</xsl:text>
+    </xsl:when>
     <xsl:when test="contains($file, 'boost/asio/spawn')">
       <xsl:text>None</xsl:text>
     </xsl:when>
@@ -840,7 +859,7 @@
   [[Name][Description]]
 <xsl:for-each select="
     sectiondef[@kind='public-type']/memberdef |
-    innerclass[@prot='public' and not(contains(., '_handler'))]" mode="class-table">
+    innerclass[@prot='public' and not(contains(., '_handler')) and not(contains(., 'thread_function'))]" mode="class-table">
   <xsl:sort select="concat(name, (.)[not(name)])"/>
   [
 <xsl:choose>
@@ -977,7 +996,7 @@
 ]
 </xsl:if>
 
-<xsl:if test="$class-name = 'io_service::service'">
+<xsl:if test="$class-name = 'execution_context::service'">
 <xsl:if test="count(sectiondef[@kind='private-func']) > 0">
 [heading Private Member Functions]
 [table
@@ -1166,7 +1185,7 @@
   <xsl:with-param name="class-id" select="$class-id"/>
   <xsl:with-param name="class-file" select="$class-file"/>
 </xsl:apply-templates>
-<xsl:if test="$class-name = 'io_service::service'">
+<xsl:if test="$class-name = 'execution_context::service'">
   <xsl:apply-templates select="sectiondef[@kind='private-func']/memberdef[not(type = 'friend class') and not(contains(name, '_helper'))]" mode="class-detail">
     <xsl:sort select="name"/>
     <xsl:with-param name="class-name" select="$class-name"/>
@@ -1191,6 +1210,11 @@
       <xsl:with-param name="text" select="$name"/>
     </xsl:call-template>
   </xsl:variable>
+  <xsl:variable name="escaped-class-name">
+    <xsl:call-template name="escape-name">
+      <xsl:with-param name="text" select="$class-name"/>
+    </xsl:call-template>
+  </xsl:variable>
   <xsl:variable name="id">
     <xsl:call-template name="make-id">
       <xsl:with-param name="name" select="$name"/>
@@ -1215,9 +1239,14 @@
 <xsl:value-of select="$class-name"/>::<xsl:value-of select="$escaped-name"/>]
 
 <xsl:text>[indexterm2 </xsl:text>
+<xsl:text>boost_asio.indexterm.</xsl:text>
+<xsl:value-of select="$class-id"/>
+<xsl:text>.</xsl:text>
+<xsl:value-of select="$id"/>
+<xsl:text>..</xsl:text>
 <xsl:value-of select="$escaped-name"/>
 <xsl:text>..</xsl:text>
-<xsl:value-of select="$class-name"/>
+<xsl:value-of select="$escaped-class-name"/>
 <xsl:text>] </xsl:text>
 
 <xsl:apply-templates select="briefdescription" mode="markup"/><xsl:text>
@@ -1272,9 +1301,14 @@
 
 <xsl:if test="$overload-count = 1">
   <xsl:text>[indexterm2 </xsl:text>
+  <xsl:text>boost_asio.indexterm.</xsl:text>
+  <xsl:value-of select="$class-id"/>
+  <xsl:text>.</xsl:text>
+  <xsl:value-of select="$id"/>
+  <xsl:text>..</xsl:text>
   <xsl:value-of select="$escaped-name"/>
   <xsl:text>..</xsl:text>
-  <xsl:value-of select="$class-name"/>
+  <xsl:value-of select="$escaped-class-name"/>
   <xsl:text>] </xsl:text>
 </xsl:if>
 
@@ -1293,6 +1327,7 @@
     <xsl:when test="@kind='enum'">
       <xsl:call-template name="enum" mode="class-detail">
         <xsl:with-param name="enum-name" select="$class-name"/>
+        <xsl:with-param name="id" select="concat($class-id, '.', $id)"/>
       </xsl:call-template>
     </xsl:when>
     <xsl:when test="@kind='function'">
@@ -1365,11 +1400,17 @@
 
 <xsl:template name="enum">
 <xsl:param name="enum-name"/>
+<xsl:param name="id"/>
   enum <xsl:value-of select="name"/><xsl:text>
 </xsl:text><xsl:if test="count(enumvalue) &gt; 0">
 <xsl:value-of select="$newline"/>
 <xsl:for-each select="enumvalue">
   <xsl:text>[indexterm2 </xsl:text>
+  <xsl:text>boost_asio.indexterm.</xsl:text>
+  <xsl:value-of select="$id"/>
+  <xsl:text>.</xsl:text>
+  <xsl:value-of select="name"/>
+  <xsl:text>..</xsl:text>
   <xsl:value-of select="name"/>
   <xsl:text>..</xsl:text>
   <xsl:value-of select="$enum-name"/>
@@ -1431,24 +1472,30 @@
         <xsl:when test="declname = 'Arg'">
           <xsl:value-of select="declname"/>
         </xsl:when>
+        <xsl:when test="declname = 'Args'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
         <xsl:when test="declname = 'BufferSequence'">
           <xsl:value-of select="declname"/>
         </xsl:when>
         <xsl:when test="declname = 'ByteType'">
           <xsl:value-of select="declname"/>
         </xsl:when>
-        <xsl:when test="declname = 'Clock'">
+        <xsl:when test="declname = 'C'">
           <xsl:value-of select="declname"/>
         </xsl:when>
-        <xsl:when test="declname = 'CompletionCondition'">
+        <xsl:when test="declname = 'Clock'">
           <xsl:value-of select="declname"/>
         </xsl:when>
-        <xsl:when test="declname = 'ConnectCondition'">
+        <xsl:when test="declname = 'CompletionToken'">
           <xsl:value-of select="declname"/>
         </xsl:when>
         <xsl:when test="declname = 'Context_Service'">
           <xsl:value-of select="declname"/>
         </xsl:when>
+        <xsl:when test="declname = 'Duration'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
         <xsl:when test="declname = 'DatagramSocketService1'">
           <xsl:value-of select="concat('``[link boost_asio.reference.DatagramSocketService ', declname, ']``')"/>
         </xsl:when>
@@ -1461,6 +1508,12 @@
         <xsl:when test="declname = 'ErrorEnum'">
           <xsl:value-of select="declname"/>
         </xsl:when>
+        <xsl:when test="declname = 'ExecutionContext'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
+        <xsl:when test="declname = 'Executor'">
+          <xsl:value-of select="concat('``[link boost_asio.reference.Executor1 ', declname, ']``')"/>
+        </xsl:when>
         <xsl:when test="declname = 'Function'">
           <xsl:value-of select="declname"/>
         </xsl:when>
@@ -1476,9 +1529,18 @@
         <xsl:when test="declname = 'OtherAllocator'">
           <xsl:value-of select="declname"/>
         </xsl:when>
+        <xsl:when test="declname = 'OtherExecutor'">
+          <xsl:value-of select="concat('``[link boost_asio.reference.Executor1 ', declname, ']``')"/>
+        </xsl:when>
+        <xsl:when test="declname = 'OtherHandler'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
         <xsl:when test="declname = 'PasswordCallback'">
           <xsl:value-of select="declname"/>
         </xsl:when>
+        <xsl:when test="declname = 'Period'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
         <xsl:when test="declname = 'PodType'">
           <xsl:value-of select="declname"/>
         </xsl:when>
@@ -1491,6 +1553,12 @@
         <xsl:when test="declname = 'RawSocketService1'">
           <xsl:value-of select="concat('``[link boost_asio.reference.RawSocketService ', declname, ']``')"/>
         </xsl:when>
+        <xsl:when test="declname = 'Rep'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
+        <xsl:when test="declname = 'Result'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
         <xsl:when test="declname = 'SeqPacketSocketService1'">
           <xsl:value-of select="concat('``[link boost_asio.reference.SeqPacketSocketService ', declname, ']``')"/>
         </xsl:when>
@@ -1527,6 +1595,9 @@
         <xsl:when test="declname = 'Traits'">
           <xsl:value-of select="declname"/>
         </xsl:when>
+        <xsl:when test="declname = 'U'">
+          <xsl:value-of select="declname"/>
+        </xsl:when>
         <xsl:when test="declname = 'VerifyCallback'">
           <xsl:value-of select="declname"/>
         </xsl:when>
@@ -1602,6 +1673,9 @@
 [section:<xsl:value-of select="$id"/><xsl:text> </xsl:text><xsl:value-of select="$name"/>]
 
 <xsl:text>[indexterm1 </xsl:text>
+<xsl:text>boost_asio.indexterm.</xsl:text>
+<xsl:value-of select="$id"/>
+<xsl:text>..</xsl:text>
 <xsl:value-of select="$name"/>
 <xsl:text>] </xsl:text>
 
@@ -1655,6 +1729,9 @@
 
 <xsl:if test="$overload-count = 1">
   <xsl:text>[indexterm1 </xsl:text>
+  <xsl:text>boost_asio.indexterm.</xsl:text>
+  <xsl:value-of select="$id"/>
+  <xsl:text>..</xsl:text>
   <xsl:value-of select="$name"/>
   <xsl:text>] </xsl:text>
 </xsl:if>
@@ -1674,6 +1751,7 @@
     <xsl:when test="@kind='enum'">
       <xsl:call-template name="enum">
         <xsl:with-param name="enum-name" select="$name"/>
+        <xsl:with-param name="id" select="$id"/>
       </xsl:call-template>
     </xsl:when>
     <xsl:when test="@kind='function'">
diff --git a/doc/requirements/AcceptHandler.qbk b/doc/requirements/AcceptHandler.qbk
index b48f4c8519..14cddeb4a8 100644
--- a/doc/requirements/AcceptHandler.qbk
+++ b/doc/requirements/AcceptHandler.qbk
@@ -35,7 +35,29 @@ An accept handler function object:
     ...
   };
 
-A non-static class member function adapted to an accept handler using `bind()`:
+A lambda as an accept handler:
+
+  acceptor.async_accept(...,
+      [](const boost::system::error_code& ec)
+      {
+        ...
+      });
+
+A non-static class member function adapted to an accept handler using
+`std::bind()`:
+
+  void my_class::accept_handler(
+      const boost::system::error_code& ec)
+  {
+    ...
+  }
+  ...
+  acceptor.async_accept(...,
+      std::bind(&my_class::accept_handler,
+        this, std::placeholders::_1));
+
+A non-static class member function adapted to an accept handler using
+`boost::bind()`:
 
   void my_class::accept_handler(
       const boost::system::error_code& ec)
diff --git a/doc/requirements/AcceptableProtocol.qbk b/doc/requirements/AcceptableProtocol.qbk
new file mode 100644
index 0000000000..50d575e3e3
--- /dev/null
+++ b/doc/requirements/AcceptableProtocol.qbk
@@ -0,0 +1,25 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:AcceptableProtocol Acceptable protocol requirements]
+
+A type `X` meets the `AcceptableProtocol` requirements if it satisfies the
+requirements of [link boost_asio.reference.Protocol `Protocol`] as well as the
+additional requirements listed below.
+
+[table AcceptableProtocol requirements
+  [[expression] [return type] [assertion/note\npre/post-conditions]]
+  [
+    [`X::socket`]
+    [A type that satisfies the requirements of `Destructible` (C++Std
+     \[destructible\]) and `MoveConstructible` (C++Std \[moveconstructible\]),
+     and that is publicly and unambiguously derived from `basic_socket<X>`.]
+    []
+  ]
+]
+
+[endsect]
diff --git a/doc/requirements/AsyncRandomAccessReadDevice.qbk b/doc/requirements/AsyncRandomAccessReadDevice.qbk
index e9e0ae5be3..0ef84f727f 100644
--- a/doc/requirements/AsyncRandomAccessReadDevice.qbk
+++ b/doc/requirements/AsyncRandomAccessReadDevice.qbk
@@ -17,10 +17,9 @@ boost_asio.reference.ReadHandler read handler] requirements.
 [table Buffer-oriented asynchronous random-access read device requirements
   [[operation] [type] [semantics, pre/post-conditions]]
   [
-    [`a.get_io_service();`]
-    [`io_service&`]
-    [Returns the `io_service` object through which the `async_read_some_at`
-    handler `h` will be invoked.]
+    [`a.get_executor()`]
+    [A type satisfying the [link boost_asio.reference.Executor1 Executor requirements].]
+    [Returns the associated I/O executor.]
   ]
   [
     [`a.async_read_some_at(o, mb, h);`]
diff --git a/doc/requirements/AsyncRandomAccessWriteDevice.qbk b/doc/requirements/AsyncRandomAccessWriteDevice.qbk
index d9ea1daf00..ca2e4c2a8b 100644
--- a/doc/requirements/AsyncRandomAccessWriteDevice.qbk
+++ b/doc/requirements/AsyncRandomAccessWriteDevice.qbk
@@ -17,10 +17,9 @@ boost_asio.reference.WriteHandler write handler] requirements.
 [table Buffer-oriented asynchronous random-access write device requirements
   [[operation] [type] [semantics, pre/post-conditions]]
   [
-    [`a.get_io_service();`]
-    [`io_service&`]
-    [Returns the `io_service` object through which the `async_write_some_at`
-    handler `h` will be invoked.]
+    [`a.get_executor()`]
+    [A type satisfying the [link boost_asio.reference.Executor1 Executor requirements].]
+    [Returns the associated I/O executor.]
   ]
   [
     [`a.async_write_some_at(o, cb, h);`]
diff --git a/doc/requirements/AsyncReadStream.qbk b/doc/requirements/AsyncReadStream.qbk
index a832aa15f7..873a6cb87c 100644
--- a/doc/requirements/AsyncReadStream.qbk
+++ b/doc/requirements/AsyncReadStream.qbk
@@ -7,48 +7,42 @@
 
 [section:AsyncReadStream Buffer-oriented asynchronous read stream requirements]
 
-In the table below, `a` denotes an asynchronous read stream object, `mb`
-denotes an object satisfying [link
-boost_asio.reference.MutableBufferSequence mutable buffer sequence]
-requirements, and `h` denotes an object satisfying [link
-boost_asio.reference.ReadHandler read handler] requirements.
+A type `X` meets the `AsyncReadStream` requirements if it satisfies the
+requirements listed below.
 
-[table Buffer-oriented asynchronous read stream requirements
+In the table below, `a` denotes a value of type `X`, `mb` denotes a (possibly
+const) value satisfying the [link boost_asio.reference.MutableBufferSequence
+`MutableBufferSequence`] requirements, and `t` is a completion token.
+
+[table AsyncReadStream requirements
   [[operation] [type] [semantics, pre/post-conditions]]
   [
-    [`a.get_io_service();`]
-    [`io_service&`]
-    [Returns the `io_service` object through which the `async_read_some`
-    handler `h` will be invoked.]
+    [`a.get_executor()`]
+    [A type satisfying the [link boost_asio.reference.Executor1 Executor requirements].]
+    [Returns the associated I/O executor.]
   ]
   [
-    [`a.async_read_some(mb, h);`]
-    [`void`]
+    [`a.async_read_some(mb,t)`]
     [
-      Initiates an asynchronous operation to read one or more bytes of data
-      from the stream `a`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The `async_read_some` operation shall always fill a buffer in
-      the sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous read operation is invoked,\n
+      The return type is determined according to the requirements for an
+      [link boost_asio.reference.asynchronous_operations asynchronous operation].
+    ]
+    [
+      Meets the requirements for a [link boost_asio.reference.read_write_operations
+      read operation] and an [link boost_asio.reference.asynchronous_operations
+      asynchronous operation] with completion signature `void(error_code ec,
+      size_t n)`.\n
       \n
-      whichever comes first.\n
+      If `buffer_size(mb) > 0`, initiates an asynchronous operation to read one
+      or more bytes of data from the stream `a` into the buffer sequence `mb`.
+      If successful, `ec` is set such that `!ec` is `true`, and `n` is the
+      number of bytes read. If an error occurred, `ec` is set such that `!!ec`
+      is `true`, and `n` is 0. If all data has been read from the stream, and
+      the stream performed an orderly shutdown, `ec` is
+      `stream_errc::eof` and `n` is 0.\n
       \n
-      If the total size of all buffers in the sequence `mb` is `0`, the
-      asynchronous read operation shall complete immediately and pass `0` as
-      the argument to the handler that specifies the number of bytes read.
+      If `buffer_size(mb) == 0`, the operation completes immediately. `ec` is
+      set such that `!ec` is `true`, and `n` is 0.
     ]
   ]
 ]
diff --git a/doc/requirements/AsyncWriteStream.qbk b/doc/requirements/AsyncWriteStream.qbk
index 9430b85724..4aa3bdeb0d 100644
--- a/doc/requirements/AsyncWriteStream.qbk
+++ b/doc/requirements/AsyncWriteStream.qbk
@@ -7,47 +7,40 @@
 
 [section:AsyncWriteStream Buffer-oriented asynchronous write stream requirements]
 
-In the table below, `a` denotes an asynchronous write stream object, `cb`
-denotes an object satisfying [link boost_asio.reference.ConstBufferSequence
-constant buffer sequence] requirements, and `h` denotes an object satisfying
-[link boost_asio.reference.WriteHandler write handler] requirements.
+A type `X` meets the `AsyncWriteStream` requirements if it satisfies the
+requirements listed below.
 
-[table Buffer-oriented asynchronous write stream requirements
+In the table below, `a` denotes a value of type `X`, `cb` denotes a (possibly
+const) value satisfying the [link boost_asio.reference.ConstBufferSequence
+`ConstBufferSequence`] requirements, and `t` is a completion token.
+
+[table AsyncWriteStream requirements
   [[operation] [type] [semantics, pre/post-conditions]]
   [
-    [`a.get_io_service();`]
-    [`io_service&`]
-    [Returns the `io_service` object through which the `async_write_some`
-    handler `h` will be invoked.]
+    [`a.get_executor()`]
+    [A type satisfying the [link boost_asio.reference.Executor1 Executor requirements].]
+    [Returns the associated I/O executor.]
   ]
   [
-    [`a.async_write_some(cb, h);`]
-    [`void`]
+    [`a.async_write_some(cb,t)`]
     [
-      Initiates an asynchronous operation to write one or more bytes of data to
-      the stream `a`. The operation is performed via the `io_service` object
-      `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The `async_write_some` operation shall always write a
-      buffer in the sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous write operation is invoked,\n
+      The return type is determined according to the requirements for an
+      [link boost_asio.reference.asynchronous_operations asynchronous operation].
+    ]
+    [
+      Meets the requirements for a [link boost_asio.reference.read_write_operations
+      write operation] and an [link boost_asio.reference.asynchronous_operations
+      asynchronous operation] with completion signature `void(error_code ec,
+      size_t n)`.\n
       \n
-      whichever comes first.\n
+      If `buffer_size(cb) > 0`, initiates an asynchronous operation to write
+      one or more bytes of data to the stream `a` from the buffer sequence
+      `cb`. If successful, `ec` is set such that `!ec` is `true`, and `n` is
+      the number of bytes written. If an error occurred, `ec` is set such that
+      `!!ec` is `true`, and `n` is 0.\n
       \n
-      If the total size of all buffers in the sequence `cb` is `0`, the
-      asynchronous write operation shall complete immediately and pass `0` as
-      the argument to the handler that specifies the number of bytes written.
+      If `buffer_size(cb) == 0`, the operation completes immediately. `ec` is
+      set such that `!ec` is `true`, and `n` is 0.
     ]
   ]
 ]
diff --git a/doc/requirements/BufferedHandshakeHandler.qbk b/doc/requirements/BufferedHandshakeHandler.qbk
index bafb53d80d..e3f4a07c1a 100644
--- a/doc/requirements/BufferedHandshakeHandler.qbk
+++ b/doc/requirements/BufferedHandshakeHandler.qbk
@@ -37,7 +37,8 @@ A buffered handshake handler function object:
     ...
   };
 
-A non-static class member function adapted to a buffered handshake handler using `bind()`:
+A non-static class member function adapted to a buffered handshake handler
+using `boost::bind()`:
 
   void my_class::handshake_handler(
       const boost::system::error_code& ec,
diff --git a/doc/requirements/CompletionCondition.qbk b/doc/requirements/CompletionCondition.qbk
new file mode 100644
index 0000000000..3e40a09c87
--- /dev/null
+++ b/doc/requirements/CompletionCondition.qbk
@@ -0,0 +1,42 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:CompletionCondition Completion condition requirements]
+
+A ['completion condition] is a function object that is used with the algorithms
+[link boost_asio.reference.read `read`], [link boost_asio.reference.async_read
+`async_read`], [link boost_asio.reference.write `write`], and [link
+boost_asio.reference.async_write `async_write`] to determine when the algorithm has
+completed transferring data.
+
+A type `X` meets the `CompletionCondition` requirements if it satisfies the
+requirements of `Destructible` (C++Std [destructible]) and
+`CopyConstructible` (C++Std [copyconstructible]), as well as the additional
+requirements listed below.
+
+In the table below, `x` denotes a value of type `X`, `ec` denotes a (possibly
+const) value of type `error_code`, and `n` denotes a (possibly const) value of
+type `size_t`.
+
+[table CompletionCondition requirements
+  [[expression] [return type] [assertion/note\npre/post-condition]]
+  [
+    [`x(ec, n)`]
+    [`size_t`]
+    [
+      Let `n` be the total number of bytes transferred by the read or write
+      algorithm so far.\n
+      \n
+      Returns the maximum number of bytes to be transferred on the next
+      `read_some`, `async_read_some`, `write_some`, or `async_write_some`
+      operation performed by the algorithm. Returns `0` to indicate that the
+      algorithm is complete.
+    ]
+  ]
+]
+
+[endsect]
diff --git a/doc/requirements/CompletionHandler.qbk b/doc/requirements/CompletionHandler.qbk
index 349f08390e..b6b1d3d78f 100644
--- a/doc/requirements/CompletionHandler.qbk
+++ b/doc/requirements/CompletionHandler.qbk
@@ -32,8 +32,26 @@ A completion handler function object:
     ...
   };
 
+A lambda as a completion handler:
+
+  my_io_service.post(
+      []()
+      {
+        ...
+      });
+
+A non-static class member function adapted to a completion handler using
+`std::bind()`:
+
+  void my_class::completion_handler()
+  {
+    ...
+  }
+  ...
+  my_io_service.post(std::bind(&my_class::completion_handler, this));
+
 A non-static class member function adapted to a completion handler using
-`bind()`:
+`boost::bind()`:
 
   void my_class::completion_handler()
   {
diff --git a/doc/requirements/ConnectCondition.qbk b/doc/requirements/ConnectCondition.qbk
new file mode 100644
index 0000000000..fa68c76d0e
--- /dev/null
+++ b/doc/requirements/ConnectCondition.qbk
@@ -0,0 +1,34 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:ConnectCondition Connect condition requirements]
+
+A type `X` meets the `ConnectCondition` requirements if it satisfies the
+requirements of `Destructible` (C++Std [destructible]) and
+`CopyConstructible` (C++Std [copyconstructible]), as well as the additional
+requirements listed below.
+
+In the table below, `x` denotes a value of type `X`, `ec` denotes a (possibly
+const) value of type `error_code`, and `ep` denotes a (possibly const) value of
+some type satisfying the [link boost_asio.reference.Endpoint endpoint] requirements.
+
+[table ConnectCondition requirements
+  [[expression] [return type] [assertion/note\npre/post-condition]]
+  [
+    [`x(ec, ep)`]
+    [`bool`]
+    [
+      Returns `true` to indicate that the `connect` or `async_connect`
+      algorithm should attempt a connection to the endpoint `ep`. Otherwise,
+      returns `false` to indicate that the algorithm should not attempt
+      connection to the endpoint `ep`, and should instead skip to the next
+      endpoint in the sequence.
+    ]
+  ]
+]
+
+[endsect]
diff --git a/doc/requirements/ConnectHandler.qbk b/doc/requirements/ConnectHandler.qbk
index bef8434ef4..1a29ca5ea4 100644
--- a/doc/requirements/ConnectHandler.qbk
+++ b/doc/requirements/ConnectHandler.qbk
@@ -35,7 +35,29 @@ A connect handler function object:
     ...
   };
 
-A non-static class member function adapted to a connect handler using `bind()`:
+A lambda as a connect handler:
+
+  socket.async_connect(...,
+      [](const boost::system::error_code& ec)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a connect handler using
+`std::bind()`:
+
+  void my_class::connect_handler(
+      const boost::system::error_code& ec)
+  {
+    ...
+  }
+  ...
+  socket.async_connect(...,
+      std::bind(&my_class::connect_handler,
+        this, std::placeholders::_1));
+
+A non-static class member function adapted to a connect handler using
+`boost::bind()`:
 
   void my_class::connect_handler(
       const boost::system::error_code& ec)
diff --git a/doc/requirements/ConstBufferSequence.qbk b/doc/requirements/ConstBufferSequence.qbk
index f708392abf..8c3306859f 100644
--- a/doc/requirements/ConstBufferSequence.qbk
+++ b/doc/requirements/ConstBufferSequence.qbk
@@ -7,96 +7,49 @@
 
 [section:ConstBufferSequence Constant buffer sequence requirements]
 
-In the table below, `X` denotes a class containing objects of type `T`, `a`
-denotes a value of type `X` and `u` denotes an identifier.
+A ['constant buffer sequence] represents a set of memory regions that may be
+used as input to an operation, such as the `send` operation of a socket.
+
+A type `X` meets the `ConstBufferSequence` requirements if it satisfies the
+requirements of `Destructible` (C++Std [destructible]) and
+`CopyConstructible` (C++Std [copyconstructible]), as well as the additional
+requirements listed below.
+
+In the table below, `x` denotes a (possibly const) value of type `X`, and `u`
+denotes an identifier.
 
 [table ConstBufferSequence requirements
   [[expression] [return type] [assertion/note\npre/post-condition]]
   [
-    [`X::value_type`]
-    [`T`]
-    [`T` meets the requirements for [link
-     boost_asio.reference.ConvertibleToConstBuffer
-     ConvertibleToConstBuffer].]
-  ]
-  [
-    [`X::const_iterator`]
-    [iterator type pointing to `T`]
-    [`const_iterator` meets the requirements for bidirectional iterators
-     (C++ Std, 24.1.4).]
-  ]
-  [
-    [`X(a);`]
+    [`boost::asio::buffer_sequence_begin(x)`\n
+     `boost::asio::buffer_sequence_end(x)`]
+    [An iterator type meeting the requirements for bidirectional iterators
+     (C++Std \[bidirectional.iterators\]) whose value type is convertible to
+     `const_buffer`.]
     []
-    [post: `equal_const_buffer_seq(a, X(a))` where the binary predicate
-     `equal_const_buffer_seq` is defined as
-     ``
-       bool equal_const_buffer_seq(
-         const X& x1, const X& x2)
-       {
-         return
-           distance(x1.begin(), x1.end())
-             == distance(x2.begin(), x2.end())
-               && equal(x1.begin(), x1.end(),
-                        x2.begin(), equal_buffer);
-       }
-     ``
-     and the binary predicate `equal_buffer` is defined as
-     ``
-      bool equal_buffer(
-        const X::value_type& v1,
-        const X::value_type& v2)
-      {
-        const_buffer b1(v1);
-        const_buffer b2(v2);
-        return
-          buffer_cast<const void*>(b1)
-            == buffer_cast<const void*>(b2)
-              && buffer_size(b1) == buffer_size(b2);
-      }
-     ``]
   ]
   [
-    [`X u(a);`]
+    [``
+      X u(x);
+    ``]
     []
-    [post:
+    [post:\n
      ``
-      distance(a.begin(), a.end())
-        == distance(u.begin(), u.end())
-          && equal(a.begin(), a.end(),
-                   u.begin(), equal_buffer)
-     ``
-     where the binary predicate `equal_buffer` is defined as
-     ``
-      bool equal_buffer(
-        const X::value_type& v1,
-        const X::value_type& v2)
-      {
-        const_buffer b1(v1);
-        const_buffer b2(v2);
-        return
-          buffer_cast<const void*>(b1)
-            == buffer_cast<const void*>(b2)
-              && buffer_size(b1) == buffer_size(b2);
-      }
+       equal(
+         boost::asio::buffer_sequence_begin(x),
+         boost::asio::buffer_sequence_end(x),
+         boost::asio::buffer_sequence_begin(u),
+         boost::asio::buffer_sequence_end(u),
+         [](const typename X::value_type& v1,
+            const typename X::value_type& v2)
+          {
+            const_buffer b1(v1);
+            const_buffer b2(v2);
+            return b1.data() == b2.data()
+                && b1.size() == b2.size();
+          })
      ``]
   ]
-  [
-    [`(&a)->~X();`]
-    [`void`]
-    [note: the destructor is applied to every element of `a`; all the memory
-     is deallocated.]
-  ]
-  [
-    [`a.begin();`]
-    [`const_iterator` or convertible to `const_iterator`]
-    []
-  ]
-  [
-    [`a.end();`]
-    [`const_iterator` or convertible to `const_iterator`]
-    []
-  ]
 ]
 
 [endsect]
diff --git a/doc/requirements/ConvertibleToConstBuffer.qbk b/doc/requirements/ConvertibleToConstBuffer.qbk
deleted file mode 100644
index 269c4a7fdb..0000000000
--- a/doc/requirements/ConvertibleToConstBuffer.qbk
+++ /dev/null
@@ -1,96 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:ConvertibleToConstBuffer Convertible to const buffer requirements]
-
-A type that meets the requirements for convertibility to a const buffer must
-meet the requirements of `CopyConstructible` types (C++ Std, 20.1.3), and the
-requirements of `Assignable` types (C++ Std, 23.1).
-
-In the table below, `X` denotes a class meeting the requirements for
-convertibility to a const buffer, `a` and `b` denote values of type `X`, and
-`u`, `v` and `w` denote identifiers.
-
-[table ConvertibleToConstBuffer requirements
-  [[expression][postcondition]]
-  [
-    [``
-      const_buffer u(a);
-      const_buffer v(a);
-    ``]
-    [``
-      buffer_cast<const void*>(u) == buffer_cast<const void*>(v)
-        && buffer_size(u) == buffer_size(v)
-    ``]
-  ]
-  [
-    [``
-      const_buffer u(a);
-      const_buffer v = a;
-    ``]
-    [``
-      buffer_cast<const void*>(u) == buffer_cast<const void*>(v)
-        && buffer_size(u) == buffer_size(v)
-    ``]
-  ]
-  [
-    [``
-      const_buffer u(a);
-      const_buffer v; v = a;
-    ``]
-    [``
-      buffer_cast<const void*>(u) == buffer_cast<const void*>(v)
-        && buffer_size(u) == buffer_size(v)
-    ``]
-  ]
-  [
-    [``
-      const_buffer u(a);
-      const X& v = a;
-      const_buffer w(v);
-    ``]
-    [``
-      buffer_cast<const void*>(u) == buffer_cast<const void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-  [
-    [``
-      const_buffer u(a);
-      X v(a);
-      const_buffer w(v);
-    ``]
-    [``
-      buffer_cast<const void*>(u) == buffer_cast<const void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-  [
-    [``
-      const_buffer u(a);
-      X v = a;
-      const_buffer w(v);
-    ``]
-    [``
-      buffer_cast<const void*>(u) == buffer_cast<const void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-  [
-    [``
-      const_buffer u(a);
-      X v(b); v = a;
-      const_buffer w(v);
-    ``]
-    [``
-      buffer_cast<const void*>(u) == buffer_cast<const void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/ConvertibleToMutableBuffer.qbk b/doc/requirements/ConvertibleToMutableBuffer.qbk
deleted file mode 100644
index 75de88bdc1..0000000000
--- a/doc/requirements/ConvertibleToMutableBuffer.qbk
+++ /dev/null
@@ -1,96 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:ConvertibleToMutableBuffer Convertible to mutable buffer requirements]
-
-A type that meets the requirements for convertibility to a mutable buffer must
-meet the requirements of `CopyConstructible` types (C++ Std, 20.1.3), and the
-requirements of `Assignable` types (C++ Std, 23.1).
-
-In the table below, `X` denotes a class meeting the requirements for
-convertibility to a mutable buffer, `a` and `b` denote values of type `X`, and
-`u`, `v` and `w` denote identifiers.
-
-[table ConvertibleToMutableBuffer requirements
-  [[expression][postcondition]]
-  [
-    [``
-      mutable_buffer u(a);
-      mutable_buffer v(a);
-    ``]
-    [``
-      buffer_cast<void*>(u) == buffer_cast<void*>(v)
-        && buffer_size(u) == buffer_size(v)
-    ``]
-  ]
-  [
-    [``
-      mutable_buffer u(a);
-      mutable_buffer v = a;
-    ``]
-    [``
-      buffer_cast<void*>(u) == buffer_cast<void*>(v)
-        && buffer_size(u) == buffer_size(v)
-    ``]
-  ]
-  [
-    [``
-      mutable_buffer u(a);
-      mutable_buffer v; v = a;
-    ``]
-    [``
-      buffer_cast<void*>(u) == buffer_cast<void*>(v)
-        && buffer_size(u) == buffer_size(v)
-    ``]
-  ]
-  [
-    [``
-      mutable_buffer u(a);
-      const X& v = a;
-      mutable_buffer w(v);
-    ``]
-    [``
-      buffer_cast<void*>(u) == buffer_cast<void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-  [
-    [``
-      mutable_buffer u(a);
-      X v(a);
-      mutable_buffer w(v);
-    ``]
-    [``
-      buffer_cast<void*>(u) == buffer_cast<void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-  [
-    [``
-      mutable_buffer u(a);
-      X v = a;
-      mutable_buffer w(v);
-    ``]
-    [``
-      buffer_cast<void*>(u) == buffer_cast<void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-  [
-    [``
-      mutable_buffer u(a);
-      X v(b); v = a;
-      mutable_buffer w(v);
-    ``]
-    [``
-      buffer_cast<void*>(u) == buffer_cast<void*>(w)
-        && buffer_size(u) == buffer_size(w)
-    ``]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/DatagramSocketService.qbk b/doc/requirements/DatagramSocketService.qbk
deleted file mode 100644
index 7091006370..0000000000
--- a/doc/requirements/DatagramSocketService.qbk
+++ /dev/null
@@ -1,227 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:DatagramSocketService Datagram socket service requirements]
-
-A datagram socket service must meet the requirements for a [link
-boost_asio.reference.SocketService socket service], as well as the
-additional requirements listed below.
-
-In the table below, `X` denotes a datagram socket service class for protocol
-[link boost_asio.reference.Protocol `Protocol`], `a` denotes a value of type
-`X`, `b` denotes a value of type `X::implementation_type`, `e` denotes a value
-of type `Protocol::endpoint`, `ec` denotes a value of type `error_code`, `f`
-denotes a value of type `socket_base::message_flags`, `mb` denotes a value
-satisfying [link boost_asio.reference.MutableBufferSequence mutable buffer
-sequence] requirements, `rh` denotes a value meeting [link
-boost_asio.reference.ReadHandler `ReadHandler`] requirements, `cb` denotes a
-value satisfying [link boost_asio.reference.ConstBufferSequence constant
-buffer sequence] requirements, and `wh` denotes a value meeting [link
-boost_asio.reference.WriteHandler `WriteHandler`] requirements.
-
-[table DatagramSocketService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.receive(b, mb, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a connected socket `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [`a.async_receive(b, mb, f, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a connected socket `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.receive_from(b, mb, e, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from an unconnected socket `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [`a.async_receive_from(b, mb, e, f, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from an unconnected socket `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      The program must ensure the object `e` is valid until the handler
-      for the asynchronous operation is invoked.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.send(b, cb, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a connected socket `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [`a.async_send(b, cb, f, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a connected socket `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.send_to(b, cb, u, f, ec);
-    ``]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to an unconnected socket `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.async_send(b, cb, u, f, wh);
-    ``]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      an unconnected socket `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/DescriptorService.qbk b/doc/requirements/DescriptorService.qbk
deleted file mode 100644
index abb9343064..0000000000
--- a/doc/requirements/DescriptorService.qbk
+++ /dev/null
@@ -1,142 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:DescriptorService Descriptor service requirements]
-
-A descriptor service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service] with support for movability,
-as well as the additional requirements listed below.
-
-In the table below, `X` denotes a descriptor service class, `a` and `ao` denote
-values of type `X`, `b` and `c` denote values of type `X::implementation_type`,
-`n` denotes a value of type `X::native_handle_type`, `ec` denotes a value of type
-`error_code`, `i` denotes a value meeting [link boost_asio.reference.IoControlCommand
-`IoControlCommand`] requirements, and `u` and `v` denote identifiers.
-
-[table DescriptorService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`X::native_handle_type`]
-    []
-    [
-      The implementation-defined native representation of a descriptor. Must
-      satisfy the requirements of `CopyConstructible` types (C++ Std, 20.1.3),
-      and the requirements of `Assignable` types (C++ Std, 23.1).
-    ]
-  ]
-  [
-    [`a.construct(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous operations, as if by calling
-      `a.close(b, ec)`.
-    ]
-  ]
-  [
-    [``
-      a.move_construct(b, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      The underlying native representation is moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.move_assign(b, ao, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      Implicitly cancels asynchronous operations associated with `b`, as if by
-      calling `a.close(b, ec)`. Then the underlying native representation is
-      moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.assign(b, n, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.is_open(b);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.is_open(v);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.close(b, ec);
-    ``]
-    [`error_code`]
-    [
-      If `a.is_open()` is true, causes any outstanding asynchronous operations
-      to complete as soon as possible. Handlers for cancelled operations shall
-      be passed the error code `error::operation_aborted`.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.native_handle(b);
-    ``]
-    [`X::native_handle_type`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.\n
-      Causes any outstanding asynchronous operations to complete as soon as
-      possible. Handlers for cancelled operations shall be passed the error
-      code `error::operation_aborted`.
-    ]
-  ]
-  [
-    [``
-      a.io_control(b, i, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/DynamicBuffer.qbk b/doc/requirements/DynamicBuffer.qbk
new file mode 100644
index 0000000000..594893aabb
--- /dev/null
+++ b/doc/requirements/DynamicBuffer.qbk
@@ -0,0 +1,93 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:DynamicBuffer Dynamic buffer requirements]
+
+A dynamic buffer encapsulates memory storage that may be automatically resized
+as required, where the memory is divided into an input sequence followed by an
+output sequence. These memory regions are internal to the dynamic buffer
+sequence, but direct access to the elements is provided to permit them to be
+efficiently used with I/O operations, such as the `send` or `receive`
+operations of a socket. Data written to the output sequence of a dynamic buffer
+sequence object is appended to the input sequence of the same object.
+
+A dynamic buffer type `X` shall satisfy the requirements of `MoveConstructible`
+(C++ Std, [moveconstructible]) types in addition to those listed below.
+
+In the table below, `X` denotes a dynamic buffer class, `x` denotes a
+value of type `X&`, `x1` denotes values of type `const X&`, and `n` denotes a
+value of type `size_t`, and `u` denotes an identifier.
+
+[table DynamicBuffer requirements
+  [[expression] [type] [assertion/note\npre/post-conditions]]
+  [
+    [`X::const_buffers_type`]
+    [type meeting [link boost_asio.reference.ConstBufferSequence ConstBufferSequence]
+     requirements.]
+    [This type represents the memory associated with the input sequence.]
+  ]
+  [
+    [`X::mutable_buffers_type`]
+    [type meeting [link boost_asio.reference.MutableBufferSequence MutableBufferSequence]
+     requirements.]
+    [This type represents the memory associated with the output sequence.]
+  ]
+  [
+    [`x1.size()`]
+    [`size_t`]
+    [Returns the size, in bytes, of the input sequence.]
+  ]
+  [
+    [`x1.max_size()`]
+    [`size_t`]
+    [Returns the permitted maximum of the sum of the sizes of the input
+     sequence and output sequence.]
+  ]
+  [
+    [`x1.capacity()`]
+    [`size_t`]
+    [Returns the maximum sum of the sizes of the input sequence and output
+     sequence that the dynamic buffer can hold without requiring reallocation.]
+  ]
+  [
+    [`x1.data()`]
+    [`X::const_buffers_type`]
+    [Returns a constant buffer sequence `u` that represents the memory
+     associated with the input sequence, and where `buffer_size(u) == size()`.]
+  ]
+  [
+    [`x.prepare(n)`]
+    [`X::mutable_buffers_type`]
+    [Requires: `size() + n <= max_size()`.\n
+     \n
+     Returns a mutable buffer sequence `u` representing the output sequence, and
+     where `buffer_size(u) == n`. The dynamic buffer reallocates memory as
+     required. All constant or mutable buffer sequences previously obtained
+     using `data()` or `prepare()` are invalidated.\n
+     \n
+     Throws: `length_error` if `size() + n > max_size()`.]
+  ]
+  [
+    [`x.commit(n)`]
+    []
+    [Appends `n` bytes from the start of the output sequence to the end of the
+     input sequence. The remainder of the output sequence is discarded. If `n`
+     is greater than the size of the output sequence, the entire output sequence
+     is appended to the input sequence. All constant or mutable buffer sequences
+     previously obtained using `data()` or `prepare()` are invalidated.]
+  ]
+  [
+    [`x.consume(n)`]
+    []
+    [Removes `n` bytes from beginning of the input sequence. If `n` is greater
+     than the size of the input sequence, the entire input sequence is removed.
+     All constant or mutable buffer sequences previously obtained using `data()`
+     or `prepare()` are invalidated.]
+  ]
+]
+
+[endsect]
diff --git a/doc/requirements/Endpoint.qbk b/doc/requirements/Endpoint.qbk
index 074bc01ff7..38ea74282a 100644
--- a/doc/requirements/Endpoint.qbk
+++ b/doc/requirements/Endpoint.qbk
@@ -7,84 +7,85 @@
 
 [section:Endpoint Endpoint requirements]
 
-An endpoint must meet the requirements of `CopyConstructible` types (C++ Std,
-20.1.3), and the requirements of `Assignable` types (C++ Std, 23.1).
+A type `X` meets the `Endpoint` requirements if it satisfies the requirements
+of `Destructible` (C++Std [destructible]), `DefaultConstructible` (C++Std
+[defaultconstructible]), `CopyConstructible` (C++Std [copyconstructible]),
+and `CopyAssignable` (C++Std [copyassignable]), as well as the additional
+requirements listed below.
 
-In the table below, `X` denotes an endpoint class, `a` denotes a value of type
-`X`, `s` denotes a size in bytes, and `u` denotes an identifier.
+In the table below, `a` denotes a (possibly const) value of type `X`, and `u`
+denotes an identifier.
 
 [table Endpoint requirements
   [[expression] [type] [assertion/note\npre/post-conditions]]
   [
     [`X::protocol_type`]
-    [type meeting [link boost_asio.reference.Protocol protocol] requirements]
+    [type meeting [link boost_asio.reference.Protocol `Protocol`] requirements]
     []
   ]
   [
-    [`X u;`]
-    []
-    []
-  ]
-  [
-    [`X();`]
-    []
-    []
-  ]
-  [
-    [`a.protocol();`]
+    [`a.protocol()`]
     [`protocol_type`]
     []
   ]
+]
+
+In the table below, `a` denotes a (possibly const) value of type `X`, `b`
+denotes a value of type `X`, and `s` denotes a (possibly const) value of a type
+that is convertible to `size_t` and denotes a size in bytes.
+
+[table Endpoint requirements for extensible implementations
+  [[expression] [type] [assertion/note\npre/post-conditions]]
   [
-    [`a.data();`]
-    [a pointer]
+    [`a.data()`]
+    [`const void*`]
     [
       Returns a pointer suitable for passing as the /address/ argument to
-      __POSIX__ functions such as __accept__, __getpeername__, __getsockname__
-      and __recvfrom__. The implementation shall perform a
-      `reinterpret_cast` on the pointer to convert it to `sockaddr*`.
+      functions such as __POSIX__ __connect__, or as the /dest_addr/ argument
+      to functions such as  __POSIX__ __sendto__. The implementation shall
+      perform a `static_cast` on the pointer to convert it to `const
+      sockaddr*`.
     ]
   ]
   [
-    [`const X& u = a;
-      u.data();`]
-    [a pointer]
+    [`b.data()`]
+    [`void*`]
     [
       Returns a pointer suitable for passing as the /address/ argument to
-      __POSIX__ functions such as __connect__, or as the /dest_addr/ argument
-      to __POSIX__ functions such as  __sendto__. The implementation shall
-      perform a `reinterpret_cast` on the pointer to convert it to `const
-      sockaddr*`.
+      functions such as __POSIX__ __accept__, __getpeername__, __getsockname__
+      and __recvfrom__. The implementation shall perform a `static_cast` on the
+      pointer to convert it to `sockaddr*`.
     ]
   ]
   [
-    [`a.size();`]
+    [`a.size()`]
     [`size_t`]
     [
       Returns a value suitable for passing as the /address_len/ argument
-      to __POSIX__ functions such as __connect__, or as the /dest_len/ argument
-      to __POSIX__ functions such as __sendto__, after appropriate integer
+      to functions such as __POSIX__ __connect__, or as the /dest_len/ argument
+      to functions such as __POSIX__ __sendto__, after appropriate integer
       conversion has been performed.
     ]
   ]
   [
-    [`a.resize(s);`]
+    [`b.resize(s)`]
     []
     [
+      pre: `s >= 0`\n
       post: `a.size() == s`\n
-      Passed the value contained in the /address_len/ argument to __POSIX__
-      functions such as __accept__, __getpeername__, __getsockname__ and
+      Passed the value contained in the /address_len/ argument to functions
+      such as __POSIX__ __accept__, __getpeername__, __getsockname__ and
       __recvfrom__, after successful completion of the function. Permitted to
-      throw an exception if the protocol associated with the endpoint object `a`
-      does not support the specified size.
+      throw an exception if the protocol associated with the endpoint object
+      `a` does not support the specified size.
     ]
   ]
   [
-    [`a.capacity();`]
+    [`a.capacity()`]
     [`size_t`]
     [
       Returns a value suitable for passing as the /address_len/ argument to
-      __POSIX__ functions such as __accept__, __getpeername__, __getsockname__
+      functions such as __POSIX__ __accept__, __getpeername__, __getsockname__
       and __recvfrom__, after appropriate integer conversion has been performed.
     ]
   ]
diff --git a/doc/requirements/EndpointSequence.qbk b/doc/requirements/EndpointSequence.qbk
new file mode 100644
index 0000000000..031fd010e9
--- /dev/null
+++ b/doc/requirements/EndpointSequence.qbk
@@ -0,0 +1,30 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:EndpointSequence Endpoint sequence requirements]
+
+A type `X` meets the `EndpointSequence` requirements if it satisfies the
+requirements of `Destructible` (C++Std [destructible]) and `CopyConstructible`
+(C++Std [copyconstructible]), as well as the additional requirements listed
+below.
+
+In the table below, `x` denotes a (possibly const) value of type `X`.
+
+[table EndpointSequence requirements
+  [[expression] [return type] [assertion/note\npre/post-condition]]
+  [
+    [`x.begin()`\n
+     `x.end()`]
+    [A type meeting the requirements for forward iterators
+     (C++Std \[forward.iterators\]) whose value type is convertible to
+     a type satisfying the [link boost_asio.reference.Endpoint `Endpoint`]
+     requirements.]
+    [[half_open_range `x.begin()`,`x.end()`] is a valid range.]
+  ]
+]
+
+[endsect]
diff --git a/doc/requirements/ExecutionContext.qbk b/doc/requirements/ExecutionContext.qbk
new file mode 100644
index 0000000000..9d4d87c90a
--- /dev/null
+++ b/doc/requirements/ExecutionContext.qbk
@@ -0,0 +1,36 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:ExecutionContext Execution context requirements]
+
+A type `X` meets the `ExecutionContext` requirements if it is publicly and
+unambiguously derived from `execution_context`, and satisfies the additional
+requirements listed below.
+
+In the table below, `x` denotes a value of type `X`.
+
+[table ExecutionContext requirements
+  [[expression] [return type] [assertion/note\npre/post-condition]]
+  [
+    [`X::executor_type`]
+    [type meeting [link boost_asio.reference.Executor1 `Executor`] requirements]
+    []
+  ]
+  [
+    [`x.~X()`]
+    []
+    [Destroys all unexecuted function objects that were submitted via an
+     executor object that is associated with the execution context.]
+  ]
+  [
+    [`x.get_executor()`]
+    [`X::executor_type`]
+    [Returns an executor object that is associated with the execution context.]
+  ]
+]
+
+[endsect]
diff --git a/doc/requirements/Executor.qbk b/doc/requirements/Executor.qbk
new file mode 100644
index 0000000000..56e521a4e4
--- /dev/null
+++ b/doc/requirements/Executor.qbk
@@ -0,0 +1,141 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:Executor1 Executor requirements]
+
+The library describes a standard set of requirements for ['executors]. A type
+meeting the `Executor` requirements embodies a set of rules for determining how
+submitted function objects are to be executed.
+
+A type `X` meets the `Executor` requirements if it satisfies the requirements of
+`CopyConstructible` (C++Std [copyconstructible]) and `Destructible` (C++Std
+[destructible]), as well as the additional requirements listed below.
+
+No constructor, comparison operator, copy operation, move operation, swap
+operation, or member functions `context`, `on_work_started`, and
+`on_work_finished` on these types shall exit via an exception.
+
+The executor copy constructor, comparison operators, and other member functions
+defined in these requirements shall not introduce data races as a result of
+concurrent calls to those functions from different threads.
+
+Let `ctx` be the execution context returned by the executor's `context()`
+member function. An executor becomes ['invalid] when the first call to
+`ctx.shutdown()` returns. The effect of calling `on_work_started`,
+`on_work_finished`, `dispatch`, `post`, or `defer` on an invalid executor is
+undefined. [inline_note The copy constructor, comparison operators, and
+`context()` member function continue to remain valid until `ctx` is destroyed.]
+
+In the table below, `x1` and `x2` denote (possibly const) values of type `X`,
+`mx1` denotes an xvalue of type `X`, `f` denotes a `MoveConstructible` (C++Std
+[moveconstructible]) function object callable with zero arguments, `a` denotes
+a (possibly const) value of type `A` meeting the `Allocator` requirements
+(C++Std [allocator.requirements]), and `u` denotes an identifier.
+
+[table Executor requirements
+  [[expression] [type] [assertion/note\npre/post-conditions]]
+  [
+    [`X u(x1);`]
+    []
+    [Shall not exit via an exception.\n
+     \n
+     post: `u == x1` and
+     `std::addressof(u.context()) == std::addressof(x1.context()).`]
+  ]
+  [
+    [`X u(mx1);`]
+    []
+    [Shall not exit via an exception.\n
+     \n
+     post: `u` equals the prior value of `mx1` and
+     `std::addressof(u.context())` equals the prior value of
+     `std::addressof(mx1.context())`.]
+  ]
+  [
+    [`x1 == x2`]
+    [`bool`]
+    [ Returns `true` only if `x1` and `x2` can be interchanged with identical
+     effects in any of the expressions defined in these type requirements.
+     [inline_note Returning `false` does not necessarily imply that the effects
+     are not identical.]\n
+     \n
+     `operator==` shall be reflexive, symmetric, and transitive, and shall not
+     exit via an exception.]
+  ]
+  [
+    [`x1 != x2`]
+    [`bool`]
+    [Same as `!(x1 == x2)`.]
+  ]
+  [
+    [`x1.context()`]
+    [`execution_context&`, or `E&` where `E` is a type that satifisfies the
+     [link boost_asio.reference.ExecutionContext `ExecutionContext`] requirements.]
+    [Shall not exit via an exception.\n
+     \n
+     The comparison operators and member functions defined in these
+     requirements shall not alter the reference returned by this function.]
+  ]
+  [
+    [`x1.on_work_started()`]
+    []
+    [Shall not exit via an exception.]
+  ]
+  [
+    [`x1.on_work_finished()`]
+    []
+    [Shall not exit via an exception.\n
+     \n
+     Precondition: A preceding call `x2.on_work_started()` where `x1 == x2`.]
+  ]
+  [
+    [`x1.dispatch(std::move(f),a)`]
+    []
+    [Effects: Creates an object `f1` initialized with
+     [^['DECAY_COPY]]`(forward<Func>(f))` (C++Std \[thread.decaycopy\]) in the
+     current thread of execution . Calls `f1()` at most once. The executor may
+     block forward progress of the caller until `f1()` finishes execution.\n
+     \n
+     Executor implementations should use the supplied allocator to allocate any
+     memory required to store the function object. Prior to invoking the
+     function object, the executor shall deallocate any memory allocated.
+     [inline_note Executors defined in this Technical Specification always use
+     the supplied allocator unless otherwise specified.]\n
+     \n
+     Synchronization: The invocation of `dispatch` synchronizes with (C++Std
+     \[intro.multithread\]) the invocation of `f1`.]
+  ]
+  [
+    [`x1.post(std::move(f),a)`\n
+     `x1.defer(std::move(f),a)`]
+    []
+    [Effects: Creates an object `f1` initialized with
+     [^['DECAY_COPY]]`(forward<Func>(f))` in the current thread of execution.
+     Calls `f1()` at most once. The executor shall not block forward progress
+     of the caller pending completion of `f1()`.\n
+     \n
+     Executor implementations should use the supplied allocator to allocate any
+     memory required to store the function object. Prior to invoking the
+     function object, the executor shall deallocate any memory allocated.
+     [inline_note Executors defined in this Technical Specification always use
+     the supplied allocator unless otherwise specified.]\n
+     \n
+     Synchronization: The invocation of `post` or `defer` synchronizes with
+     (C++Std \[intro.multithread\]) the invocation of `f1`.\n
+     \n
+     [inline_note Although the requirements placed on `defer` are identical to
+     `post`, the use of `post` conveys a preference that the caller ['does not]
+     block the first step of [^f1]'s progress, whereas `defer` conveys a
+     preference that the caller ['does] block the first step of [^f1]. One use
+     of `defer` is to convey the intention of the caller that [^f1] is a
+     continuation of the current call context. The executor may use this
+     information to optimize or otherwise adjust the way in which `f1` is
+     invoked.]]
+  ]
+]
+
+[endsect]
diff --git a/doc/requirements/GettableSocketOption.qbk b/doc/requirements/GettableSocketOption.qbk
index 79b92942e5..2211629a2c 100644
--- a/doc/requirements/GettableSocketOption.qbk
+++ b/doc/requirements/GettableSocketOption.qbk
@@ -7,14 +7,19 @@
 
 [section:GettableSocketOption Gettable socket option requirements]
 
-In the table below, `X` denotes a socket option class, `a` denotes a value of
-`X`, `p` denotes a value that meets the [link boost_asio.reference.Protocol
-protocol] requirements, and `u` denotes an identifier.
+A type `X` meets the `GettableSocketOption` requirements if it satisfies the
+requirements listed below.
 
-[table GettableSocketOption requirements
+In the table below, `a` denotes a (possibly const) value of type `X`, `b`
+denotes a value of type `X`, `p` denotes a (possibly const) value that meets
+the [link boost_asio.reference.Protocol `Protocol`] requirements, and `s` denotes a
+(possibly const) value of a type that is convertible to `size_t` and denotes a
+size in bytes.
+
+[table GettableSocketOption requirements for extensible implementations
   [[expression] [type] [assertion/note\npre/post-conditions]]
   [
-    [`a.level(p);`]
+    [`a.level(p)`]
     [`int`]
     [
       Returns a value suitable for passing as the /level/ argument to __POSIX__
@@ -22,7 +27,7 @@ protocol] requirements, and `u` denotes an identifier.
     ]
   ]
   [
-    [`a.name(p);`]
+    [`a.name(p)`]
     [`int`]
     [
       Returns a value suitable for passing as the /option_name/ argument to
@@ -30,15 +35,15 @@ protocol] requirements, and `u` denotes an identifier.
     ]
   ]
   [
-    [`a.data(p);`]
-    [a pointer, convertible to `void*`]
+    [`b.data(p)`]
+    [`void*`]
     [
       Returns a pointer suitable for passing as the /option_value/ argument to
       __POSIX__ __getsockopt__ (or equivalent).
     ]
   ]
   [
-    [`a.size(p);`]
+    [`a.size(p)`]
     [`size_t`]
     [
       Returns a value suitable for passing as the /option_len/ argument to
@@ -47,13 +52,13 @@ protocol] requirements, and `u` denotes an identifier.
     ]
   ]
   [
-    [`a.resize(p, s);`]
+    [`b.resize(p,s)`]
     []
     [
-      post: `a.size(p) == s`.\n
+      post: `b.size(p) == s`.\n
       Passed the value contained in the /option_len/ argument to __POSIX__
       __getsockopt__ (or equivalent) after successful completion of the
-      function. Permitted to throw an exception if the socket option object `a`
+      function. Permitted to throw an exception if the socket option object `b`
       does not support the specified size.
     ]
   ]
diff --git a/doc/requirements/HandleService.qbk b/doc/requirements/HandleService.qbk
deleted file mode 100644
index 74b1ebcbd5..0000000000
--- a/doc/requirements/HandleService.qbk
+++ /dev/null
@@ -1,132 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:HandleService Handle service requirements]
-
-A handle service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service] with support for movability,
-as well as the additional requirements listed below.
-
-In the table below, `X` denotes a handle service class, `a` and `ao` denote
-values of type `X`, `b` and `c` denote values of type `X::implementation_type`,
-`n` denotes a value of type `X::native_handle_type`, `ec` denotes a value of
-type `error_code`, and `u` and `v` denote identifiers.
-
-[table HandleService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`X::native_handle_type`]
-    []
-    [
-      The implementation-defined native representation of a handle. Must
-      satisfy the requirements of `CopyConstructible` types (C++ Std, 20.1.3),
-      and the requirements of `Assignable` types (C++ Std, 23.1).
-    ]
-  ]
-  [
-    [`a.construct(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous operations, as if by calling
-      `a.close(b, ec)`.
-    ]
-  ]
-  [
-    [``
-      a.move_construct(b, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      The underlying native representation is moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.move_assign(b, ao, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      Implicitly cancels asynchronous operations associated with `b`, as if by
-      calling `a.close(b, ec)`. Then the underlying native representation is
-      moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.assign(b, n, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.is_open(b);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.is_open(v);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.close(b, ec);
-    ``]
-    [`error_code`]
-    [
-      If `a.is_open()` is true, causes any outstanding asynchronous operations
-      to complete as soon as possible. Handlers for cancelled operations shall
-      be passed the error code `error::operation_aborted`.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.native_handle(b);
-    ``]
-    [`X::native_handle_type`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.\n
-      Causes any outstanding asynchronous operations to complete as soon as
-      possible. Handlers for cancelled operations shall be passed the error
-      code `error::operation_aborted`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/HandshakeHandler.qbk b/doc/requirements/HandshakeHandler.qbk
index 71ac4041cf..dbcc9685c6 100644
--- a/doc/requirements/HandshakeHandler.qbk
+++ b/doc/requirements/HandshakeHandler.qbk
@@ -35,7 +35,29 @@ A handshake handler function object:
     ...
   };
 
-A non-static class member function adapted to a handshake handler using `bind()`:
+A lambda as a handshake handler:
+
+  ssl_stream.async_handshake(...,
+      [](const boost::system::error_code& ec)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a handshake handler using
+`std::bind()`:
+
+  void my_class::handshake_handler(
+      const boost::system::error_code& ec)
+  {
+    ...
+  }
+  ...
+  ssl_stream.async_handshake(...,
+      std::bind(&my_class::handshake_handler,
+        this, std::placeholders::_1));
+
+A non-static class member function adapted to a handshake handler using
+`boost::bind()`:
 
   void my_class::handshake_handler(
       const boost::system::error_code& ec)
diff --git a/doc/requirements/InternetProtocol.qbk b/doc/requirements/InternetProtocol.qbk
index 98fb040a7e..106ffe909f 100644
--- a/doc/requirements/InternetProtocol.qbk
+++ b/doc/requirements/InternetProtocol.qbk
@@ -7,12 +7,12 @@
 
 [section:InternetProtocol Internet protocol requirements]
 
-An internet protocol must meet the requirements for a [link
-boost_asio.reference.Protocol protocol] as well as the additional
-requirements listed below.
+A type `X` meets the `InternetProtocol` requirements if it satisfies the
+requirements of [link boost_asio.reference.AcceptableProtocol `AcceptableProtocol`],
+as well as the additional requirements listed below.
 
-In the table below, `X` denotes an internet protocol class, `a` denotes a value
-of type `X`, and `b` denotes a value of type `X`.
+In the table below, `a` denotes a (possibly const) value of type `X`, and `b`
+denotes a (possibly const) value of type `X`.
 
 [table InternetProtocol requirements
   [[expression] [return type] [assertion/note\npre/post-conditions]]
@@ -34,7 +34,8 @@ of type `X`, and `b` denotes a value of type `X`.
   [
     [`a == b`]
     [convertible to `bool`]
-    [Returns whether two protocol objects are equal.]
+    [Returns `true` if `a` and `b` represent the same IP protocol version,
+     otherwise `false`.]
   ]
   [
     [`a != b`]
diff --git a/doc/requirements/IoControlCommand.qbk b/doc/requirements/IoControlCommand.qbk
index 5bc61e7310..3cd6bf5c24 100644
--- a/doc/requirements/IoControlCommand.qbk
+++ b/doc/requirements/IoControlCommand.qbk
@@ -7,13 +7,16 @@
 
 [section:IoControlCommand I/O control command requirements]
 
-In the table below, `X` denotes an I/O control command class, `a` denotes a
-value of `X`, and `u` denotes an identifier.
+A type `X` meets the `IoControlCommand` requirements if it satisfies the
+requirements listed below.
 
-[table IoControlCommand requirements
+In the table below, `a` denotes a (possibly const) value of type `X`, and `b`
+denotes a value of type `X`.
+
+[table IoControlCommand requirements for extensible implementations
   [[expression] [type] [assertion/note\npre/post-conditions]]
   [
-    [`a.name();`]
+    [`a.name()`]
     [`int`]
     [
       Returns a value suitable for passing as the /request/ argument to
@@ -21,8 +24,8 @@ value of `X`, and `u` denotes an identifier.
     ]
   ]
   [
-    [`a.data();`]
-    [a pointer, convertible to `void*`]
+    [`b.data()`]
+    [`void*`]
     [
     ]
   ]
diff --git a/doc/requirements/ComposedConnectHandler.qbk b/doc/requirements/IteratorConnectHandler.qbk
similarity index 53%
rename from doc/requirements/ComposedConnectHandler.qbk
rename to doc/requirements/IteratorConnectHandler.qbk
index 1df6a69f96..a9bc88a565 100644
--- a/doc/requirements/ComposedConnectHandler.qbk
+++ b/doc/requirements/IteratorConnectHandler.qbk
@@ -5,17 +5,17 @@
  / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  /]
 
-[section:ComposedConnectHandler Composed connect handler requirements]
+[section:IteratorConnectHandler Iterator connect handler requirements]
 
-A composed connect handler must meet the requirements for a [link
-boost_asio.reference.Handler handler]. A value `h` of a composed connect handler
+An iterator connect handler must meet the requirements for a [link
+boost_asio.reference.Handler handler]. A value `h` of an iterator connect handler
 class should work correctly in the expression `h(ec, i)`, where `ec` is an
 lvalue of type `const error_code` and `i` is an lvalue of the type `Iterator`
 used in the corresponding `connect()` or async_connect()` function.
 
 [heading Examples]
 
-A free function as a composed connect handler:
+A free function as an iterator connect handler:
 
   void connect_handler(
       const boost::system::error_code& ec,
@@ -24,7 +24,7 @@ A free function as a composed connect handler:
     ...
   }
 
-A composed connect handler function object:
+An iterator connect handler function object:
 
   struct connect_handler
   {
@@ -39,7 +39,32 @@ A composed connect handler function object:
     ...
   };
 
-A non-static class member function adapted to a composed connect handler using `bind()`:
+A lambda as an iterator connect handler:
+
+  boost::asio::async_connect(...,
+      [](const boost::system::error_code& ec,
+        boost::asio::ip::tcp::resolver::iterator iterator)
+      {
+        ...
+      });
+
+A non-static class member function adapted to an iterator connect handler using
+`std::bind()`:
+
+  void my_class::connect_handler(
+      const boost::system::error_code& ec,
+      boost::asio::ip::tcp::resolver::iterator iterator)
+  {
+    ...
+  }
+  ...
+  boost::asio::async_connect(...,
+      std::bind(&my_class::connect_handler,
+        this, std::placeholders::_1,
+        std::placeholders::_2));
+
+A non-static class member function adapted to an iterator connect handler using
+`boost::bind()`:
 
   void my_class::connect_handler(
       const boost::system::error_code& ec,
diff --git a/doc/requirements/MoveAcceptHandler.qbk b/doc/requirements/MoveAcceptHandler.qbk
new file mode 100644
index 0000000000..2f26d566a8
--- /dev/null
+++ b/doc/requirements/MoveAcceptHandler.qbk
@@ -0,0 +1,61 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:MoveAcceptHandler Move accept handler requirements]
+
+A move accept handler must meet the requirements for a [link
+boost_asio.reference.Handler handler]. A value `h` of a move accept handler class
+should work correctly in the expression `h(ec, s)`, where `ec` is an lvalue of
+type `const error_code` and `s` is an lvalue of the nested type
+`Protocol::socket` for the type `Protocol` of the socket class template.
+
+[heading Examples]
+
+A free function as a move accept handler:
+
+  void accept_handler(
+      const boost::system::error_code& ec, boost::asio::ip::tcp::socket s)
+  {
+    ...
+  }
+
+A move accept handler function object:
+
+  struct accept_handler
+  {
+    ...
+    void operator()(
+        const boost::system::error_code& ec, boost::asio::ip::tcp::socket s)
+    {
+      ...
+    }
+    ...
+  };
+
+A lambda as a move accept handler:
+
+  acceptor.async_accept(...,
+      [](const boost::system::error_code& ec, boost::asio::ip::tcp::socket s)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a move accept handler using
+`std::bind()`:
+
+  void my_class::accept_handler(
+      const boost::system::error_code& ec, boost::asio::ip::tcp::socket socket)
+  {
+    ...
+  }
+  ...
+  boost::asio::async_accept(...,
+      std::bind(&my_class::accept_handler,
+        this, std::placeholders::_1,
+        std::placeholders::_2));
+
+[endsect]
diff --git a/doc/requirements/MutableBufferSequence.qbk b/doc/requirements/MutableBufferSequence.qbk
index f87a3b4794..8e35d66ae6 100644
--- a/doc/requirements/MutableBufferSequence.qbk
+++ b/doc/requirements/MutableBufferSequence.qbk
@@ -7,96 +7,50 @@
 
 [section:MutableBufferSequence Mutable buffer sequence requirements]
 
-In the table below, `X` denotes a class containing objects of type `T`, `a`
-denotes a value of type `X` and `u` denotes an identifier.
+A ['mutable buffer sequence] represents a set of memory regions that may be
+used to receive the output of an operation, such as the `receive` operation of
+a socket.
+
+A type `X` meets the `MutableBufferSequence` requirements if it satisfies the
+requirements of `Destructible` (C++Std [destructible]) and
+`CopyConstructible` (C++Std [copyconstructible]), as well as the additional
+requirements listed below.
+
+In the table below, `x` denotes a (possibly const) value of type `X`, and `u`
+denotes an identifier.
 
 [table MutableBufferSequence requirements
   [[expression] [return type] [assertion/note\npre/post-condition]]
   [
-    [`X::value_type`]
-    [`T`]
-    [`T` meets the requirements for [link
-     boost_asio.reference.ConvertibleToMutableBuffer
-     ConvertibleToMutableBuffer].]
-  ]
-  [
-    [`X::const_iterator`]
-    [iterator type pointing to `T`]
-    [`const_iterator` meets the requirements for bidirectional iterators
-     (C++ Std, 24.1.4).]
-  ]
-  [
-    [`X(a);`]
+    [`boost::asio::buffer_sequence_begin(x)`\n
+     `boost::asio::buffer_sequence_end(x)`]
+    [An iterator type meeting the requirements for bidirectional iterators
+     (C++Std \[bidirectional.iterators\]) whose value type is convertible to
+     `mutable_buffer`.]
     []
-    [post: `equal_mutable_buffer_seq(a, X(a))` where the binary predicate
-     `equal_mutable_buffer_seq` is defined as
-     ``
-       bool equal_mutable_buffer_seq(
-         const X& x1, const X& x2)
-       {
-         return
-           distance(x1.begin(), x1.end())
-             == distance(x2.begin(), x2.end())
-               && equal(x1.begin(), x1.end(),
-                        x2.begin(), equal_buffer);
-       }
-     ``
-     and the binary predicate `equal_buffer` is defined as
-     ``
-      bool equal_buffer(
-        const X::value_type& v1,
-        const X::value_type& v2)
-      {
-        mutable_buffer b1(v1);
-        mutable_buffer b2(v2);
-        return
-          buffer_cast<const void*>(b1)
-            == buffer_cast<const void*>(b2)
-              && buffer_size(b1) == buffer_size(b2);
-      }
-     ``]
   ]
   [
-    [`X u(a);`]
+    [``
+      X u(x);
+    ``]
     []
-    [post:
+    [post:\n
      ``
-      distance(a.begin(), a.end())
-        == distance(u.begin(), u.end())
-          && equal(a.begin(), a.end(),
-                   u.begin(), equal_buffer)
-     ``
-     where the binary predicate `equal_buffer` is defined as
-     ``
-      bool equal_buffer(
-        const X::value_type& v1,
-        const X::value_type& v2)
-      {
-        mutable_buffer b1(v1);
-        mutable_buffer b2(v2);
-        return
-          buffer_cast<const void*>(b1)
-            == buffer_cast<const void*>(b2)
-              && buffer_size(b1) == buffer_size(b2);
-      }
+       equal(
+         boost::asio::buffer_sequence_begin(x),
+         boost::asio::buffer_sequence_end(x),
+         boost::asio::buffer_sequence_begin(u),
+         boost::asio::buffer_sequence_end(u),
+         [](const typename X::value_type& v1,
+            const typename X::value_type& v2)
+          {
+            mutable_buffer b1(v1);
+            mutable_buffer b2(v2);
+            return b1.data() == b2.data()
+                && b1.size() == b2.size();
+          })
      ``]
   ]
-  [
-    [`(&a)->~X();`]
-    [`void`]
-    [note: the destructor is applied to every element of `a`; all the memory
-     is deallocated.]
-  ]
-  [
-    [`a.begin();`]
-    [`const_iterator` or convertible to `const_iterator`]
-    []
-  ]
-  [
-    [`a.end();`]
-    [`const_iterator` or convertible to `const_iterator`]
-    []
-  ]
 ]
 
 [endsect]
diff --git a/doc/requirements/ObjectHandleService.qbk b/doc/requirements/ObjectHandleService.qbk
deleted file mode 100644
index f0491c74b5..0000000000
--- a/doc/requirements/ObjectHandleService.qbk
+++ /dev/null
@@ -1,46 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:ObjectHandleService Object handle service requirements]
-
-An object handle service must meet the requirements for a [link
-boost_asio.reference.HandleService handle service], as well as the additional
-requirements listed below.
-
-In the table below, `X` denotes an object handle service class, `a` denotes a
-value of type `X`, `b` denotes a value of type `X::implementation_type`, `ec`
-denotes a value of type `error_code`, and `wh` denotes a value meeting [link
-boost_asio.reference.WaitHandler `WaitHandler`] requirements.
-
-[table ObjectHandleService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.wait(b, ec);`]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Synchronously waits for the object represented by handle `b` to become
-      signalled.
-    ]
-  ]
-  [
-    [`a.async_wait(b, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to wait for the object represented by
-      handle `b` to become signalled. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/ProtoAllocator.qbk b/doc/requirements/ProtoAllocator.qbk
new file mode 100644
index 0000000000..f08fb2449f
--- /dev/null
+++ b/doc/requirements/ProtoAllocator.qbk
@@ -0,0 +1,19 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:ProtoAllocator Proto-allocator requirements]
+
+A type `A` meets the proto-allocator requirements if `A` is `CopyConstructible`
+(C++Std [copyconstructible]), `Destructible` (C++Std [destructible]), and
+`allocator_traits<A>::rebind_alloc<U>` meets the allocator requirements (C++Std
+[allocator.requirements]), where `U` is an object type. [inline_note For
+example, `std::allocator<void>` meets the proto-allocator requirements but not
+the allocator requirements.] No constructor, comparison operator, copy
+operation, move operation, or swap operation on these types shall exit via an
+exception.
+
+[endsect]
diff --git a/doc/requirements/Protocol.qbk b/doc/requirements/Protocol.qbk
index 90ac26b3c3..0e7bb7bcf7 100644
--- a/doc/requirements/Protocol.qbk
+++ b/doc/requirements/Protocol.qbk
@@ -7,11 +7,10 @@
 
 [section:Protocol Protocol requirements]
 
-A protocol must meet the requirements of `CopyConstructible` types (C++ Std,
-20.1.3), and the requirements of `Assignable` types (C++ Std, 23.1).
-
-In the table below, `X` denotes a protocol class, and `a` denotes a value of
-`X`.
+A type `X` meets the `Protocol` requirements if it satisfies the requirements
+of `Destructible` (C++Std [destructible]), `CopyConstructible` (C++Std
+[copyconstructible]), and `CopyAssignable` (C++Std [copyassignable]), as well
+as the additional requirements listed below.
 
 [table Protocol requirements
   [[expression] [return type] [assertion/note\npre/post-conditions]]
@@ -20,6 +19,12 @@ In the table below, `X` denotes a protocol class, and `a` denotes a value of
     [type meeting [link boost_asio.reference.Endpoint endpoint] requirements]
     []
   ]
+]
+
+In the table below, `a` denotes a (possibly const) value of type `X`.
+
+[table Protocol requirements for extensible implementations
+  [[expression] [return type] [assertion/note\npre/post-conditions]]
   [
     [`a.family()`]
     [`int`]
diff --git a/doc/requirements/RandomAccessHandleService.qbk b/doc/requirements/RandomAccessHandleService.qbk
deleted file mode 100644
index 972a87a51c..0000000000
--- a/doc/requirements/RandomAccessHandleService.qbk
+++ /dev/null
@@ -1,133 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:RandomAccessHandleService Random access handle service requirements]
-
-A random access handle service must meet the requirements for a [link
-boost_asio.reference.HandleService handle service], as well as the additional
-requirements listed below.
-
-In the table below, `X` denotes a random access handle service class, `a`
-denotes a value of type `X`, `b` denotes a value of type
-`X::implementation_type`, `ec` denotes a value of type `error_code`, `o`
-denotes an offset of type boost::uint64_t, `mb` denotes a value satisfying
-[link boost_asio.reference.MutableBufferSequence mutable buffer sequence]
-requirements, `rh` denotes a value meeting [link boost_asio.reference.ReadHandler
-`ReadHandler`] requirements, `cb` denotes a value satisfying [link
-boost_asio.reference.ConstBufferSequence constant buffer sequence] requirements, and
-`wh` denotes a value meeting [link boost_asio.reference.WriteHandler `WriteHandler`]
-requirements.
-
-[table RandomAccessHandleService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.read_some_at(b, o, mb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a handle `b` at offset `o`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `mb` is `0`, the
-      function shall return `0` immediately.
-    ]
-  ]
-  [
-    [`a.async_read_some_at(b, o, mb, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a handle `b` at offset `o`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `mb` is `0`, the asynchronous read operation shall complete immediately
-      and pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.write_some_at(b, o, cb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a handle `b` at offset `o`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `cb` is `0`, the
-      function shall return `0` immediately.
-    ]
-  ]
-  [
-    [`a.async_write_some_at(b, o, cb, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a handle `b` at offset `o`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `cb` is `0`, the asynchronous operation shall complete immediately and
-      pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/RangeConnectHandler.qbk b/doc/requirements/RangeConnectHandler.qbk
new file mode 100644
index 0000000000..c986b8fc24
--- /dev/null
+++ b/doc/requirements/RangeConnectHandler.qbk
@@ -0,0 +1,82 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:RangeConnectHandler Range connect handler requirements]
+
+A range connect handler must meet the requirements for a [link
+boost_asio.reference.Handler handler]. A value `h` of a range connect handler class
+should work correctly in the expression `h(ec, ep)`, where `ec` is an lvalue of
+type `const error_code` and `ep` is an lvalue of the type `Protocol::endpoint`
+for the `Protocol` type in the corresponding `connect()` or async_connect()`
+function.
+
+[heading Examples]
+
+A free function as a range connect handler:
+
+  void connect_handler(
+      const boost::system::error_code& ec,
+      const boost::asio::ip::tcp::endpoint& endpoint)
+  {
+    ...
+  }
+
+A range connect handler function object:
+
+  struct connect_handler
+  {
+    ...
+    template <typename Range>
+    void operator()(
+        const boost::system::error_code& ec,
+        const boost::asio::ip::tcp::endpoint& endpoint)
+    {
+      ...
+    }
+    ...
+  };
+
+A lambda as a range connect handler:
+
+  boost::asio::async_connect(...,
+      [](const boost::system::error_code& ec,
+        const boost::asio::ip::tcp::endpoint& endpoint)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a range connect handler using
+`std::bind()`:
+
+  void my_class::connect_handler(
+      const boost::system::error_code& ec,
+      const boost::asio::ip::tcp::endpoint& endpoint)
+  {
+    ...
+  }
+  ...
+  boost::asio::async_connect(...,
+      std::bind(&my_class::connect_handler,
+        this, std::placeholders::_1,
+        std::placeholders::_2));
+
+A non-static class member function adapted to a range connect handler using
+`boost::bind()`:
+
+  void my_class::connect_handler(
+      const boost::system::error_code& ec,
+      const boost::asio::ip::tcp::endpoint& endpoint)
+  {
+    ...
+  }
+  ...
+  boost::asio::async_connect(...,
+      boost::bind(&my_class::connect_handler,
+        this, boost::asio::placeholders::error,
+        boost::asio::placeholders::endpoint));
+
+[endsect]
diff --git a/doc/requirements/RawSocketService.qbk b/doc/requirements/RawSocketService.qbk
deleted file mode 100644
index 403c57e65d..0000000000
--- a/doc/requirements/RawSocketService.qbk
+++ /dev/null
@@ -1,227 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:RawSocketService Raw socket service requirements]
-
-A raw socket service must meet the requirements for a [link
-boost_asio.reference.SocketService socket service], as well as the additional
-requirements listed below.
-
-In the table below, `X` denotes a raw socket service class for protocol
-[link boost_asio.reference.Protocol `Protocol`], `a` denotes a value of type
-`X`, `b` denotes a value of type `X::implementation_type`, `e` denotes a value
-of type `Protocol::endpoint`, `ec` denotes a value of type `error_code`, `f`
-denotes a value of type `socket_base::message_flags`, `mb` denotes a value
-satisfying [link boost_asio.reference.MutableBufferSequence mutable buffer
-sequence] requirements, `rh` denotes a value meeting [link
-boost_asio.reference.ReadHandler `ReadHandler`] requirements, `cb` denotes a
-value satisfying [link boost_asio.reference.ConstBufferSequence constant
-buffer sequence] requirements, and `wh` denotes a value meeting [link
-boost_asio.reference.WriteHandler `WriteHandler`] requirements.
-
-[table RawSocketService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.receive(b, mb, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a connected socket `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [`a.async_receive(b, mb, f, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a connected socket `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.receive_from(b, mb, e, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from an unconnected socket `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [`a.async_receive_from(b, mb, e, f, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from an unconnected socket `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      The program must ensure the object `e` is valid until the handler
-      for the asynchronous operation is invoked.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.send(b, cb, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a connected socket `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [`a.async_send(b, cb, f, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a connected socket `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.send_to(b, cb, u, f, ec);
-    ``]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to an unconnected socket `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.async_send(b, cb, u, f, wh);
-    ``]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      an unconnected socket `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/ReadHandler.qbk b/doc/requirements/ReadHandler.qbk
index 09b58bcbce..f6bbac390e 100644
--- a/doc/requirements/ReadHandler.qbk
+++ b/doc/requirements/ReadHandler.qbk
@@ -37,7 +37,32 @@ A read handler function object:
     ...
   };
 
-A non-static class member function adapted to a read handler using `bind()`:
+A lambda as a read handler:
+
+  socket.async_read(...
+      [](const boost::system::error_code& ec,
+        std::size_t bytes_transferred)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a read handler using
+`std::bind()`:
+
+  void my_class::read_handler(
+      const boost::system::error_code& ec,
+      std::size_t bytes_transferred)
+  {
+    ...
+  }
+  ...
+  socket.async_read(...,
+      std::bind(&my_class::read_handler,
+        this, std::placeholders::_1,
+        std::placeholders::_2));
+
+A non-static class member function adapted to a read handler using
+`boost::bind()`:
 
   void my_class::read_handler(
       const boost::system::error_code& ec,
diff --git a/doc/requirements/ResolveHandler.qbk b/doc/requirements/ResolveHandler.qbk
index 14eea5ccc3..d622a9559b 100644
--- a/doc/requirements/ResolveHandler.qbk
+++ b/doc/requirements/ResolveHandler.qbk
@@ -7,13 +7,13 @@
 
 [section:ResolveHandler Resolve handler requirements]
 
-A resolve handler must meet the requirements for a [link
-boost_asio.reference.Handler handler]. A value `h` of a resolve handler
-class should work correctly in the expression `h(ec, i)`, where `ec` is an
-lvalue of type `const error_code` and `i` is an lvalue of type `const
-ip::basic_resolver_iterator<InternetProtocol>`. `InternetProtocol` is the
-template parameter of the [link boost_asio.reference.ip__resolver_service
-`resolver_service`] which is used to initiate the asynchronous operation.
+A resolve handler must meet the requirements for a [link boost_asio.reference.Handler
+handler]. A value `h` of a resolve handler class should work correctly in the
+expression `h(ec, r)`, where `ec` is an lvalue of type `const error_code` and
+`r` is an lvalue of type `const ip::basic_resolver_results<InternetProtocol>`.
+`InternetProtocol` is the template parameter of the [link
+boost_asio.reference.ip__basic_resolver `ip::basic_resolver<>`] which is used to
+initiate the asynchronous operation.
 
 [heading Examples]
 
@@ -21,7 +21,7 @@ A free function as a resolve handler:
 
   void resolve_handler(
       const boost::system::error_code& ec,
-      boost::asio::ip::tcp::resolver::iterator iterator)
+      boost::asio::ip::tcp::resolver::results_type results)
   {
     ...
   }
@@ -33,18 +33,43 @@ A resolve handler function object:
     ...
     void operator()(
         const boost::system::error_code& ec,
-        boost::asio::ip::tcp::resolver::iterator iterator)
+        boost::asio::ip::tcp::resolver::results_type results)
     {
       ...
     }
     ...
   };
 
-A non-static class member function adapted to a resolve handler using `bind()`:
+A lambda as a resolve handler:
+
+  resolver.async_resolve(...,
+      [](const boost::system::error_code& ec,
+        boost::asio::ip::tcp::resolver::results_type results)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a resolve handler using
+`std::bind()`:
+
+  void my_class::resolve_handler(
+      const boost::system::error_code& ec,
+      boost::asio::ip::tcp::resolver::results_type results)
+  {
+    ...
+  }
+  ...
+  resolver.async_resolve(...,
+      std::bind(&my_class::resolve_handler,
+        this, std::placeholders::_1,
+        std::placeholders::_2));
+
+A non-static class member function adapted to a resolve handler using
+`boost::bind()`:
 
   void my_class::resolve_handler(
       const boost::system::error_code& ec,
-      boost::asio::ip::tcp::resolver::iterator iterator)
+      boost::asio::ip::tcp::resolver::results_type results)
   {
     ...
   }
@@ -52,6 +77,6 @@ A non-static class member function adapted to a resolve handler using `bind()`:
   resolver.async_resolve(...,
       boost::bind(&my_class::resolve_handler,
         this, boost::asio::placeholders::error,
-        boost::asio::placeholders::iterator));
+        boost::asio::placeholders::results));
 
 [endsect]
diff --git a/doc/requirements/ResolverService.qbk b/doc/requirements/ResolverService.qbk
deleted file mode 100644
index cfe69fef73..0000000000
--- a/doc/requirements/ResolverService.qbk
+++ /dev/null
@@ -1,108 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:ResolverService Resolver service requirements]
-
-A resolver service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service], as well as the
-additional requirements listed below.
-
-In the table below, `X` denotes a resolver service class for protocol
-`InternetProtocol`, `a` denotes a value of type `X`, `b` denotes a value of
-type `X::implementation_type`, `q` denotes a value of type
-`ip::basic_resolver_query<InternetProtocol>`, `e` denotes a value of type
-`ip::basic_endpoint<InternetProtocol>`, `ec` denotes a value of type
-`error_code`, and `h` denotes a value meeting [link
-boost_asio.reference.ResolveHandler `ResolveHandler`] requirements.
-
-[table ResolverService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous resolve operations, as if by
-      calling `a.cancel(b, ec)`.
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, ec);
-    ``]
-    [`error_code`]
-    [
-      Causes any outstanding asynchronous resolve operations to complete as
-      soon as possible. Handlers for cancelled operations shall be passed the
-      error code `error::operation_aborted`.
-    ]
-  ]
-  [
-    [``
-      a.resolve(b, q, ec);
-    ``]
-    [``
-      ip::basic_resolver_iterator<
-        InternetProtocol>
-    ``]
-    [
-      On success, returns an iterator `i` such that `i !=
-      ip::basic_resolver_iterator<InternetProtocol>()`. Otherwise returns
-      `ip::basic_resolver_iterator<InternetProtocol>()`.
-    ]
-  ]
-  [
-    [``
-      a.async_resolve(b, q, h);
-    ``]
-    []
-    [
-      Initiates an asynchronous resolve operation that is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      If the operation completes successfully, the `ResolveHandler` object `h`
-      shall be invoked with an iterator object `i` such that the condition `i
-      != ip::basic_resolver_iterator<InternetProtocol>()` holds. Otherwise it
-      is invoked with `ip::basic_resolver_iterator<InternetProtocol>()`.
-    ]
-  ]
-  [
-    [``
-      a.resolve(b, e, ec);
-    ``]
-    [``
-      ip::basic_resolver_iterator<
-        InternetProtocol>
-    ``]
-    [
-      On success, returns an iterator `i` such that `i !=
-      ip::basic_resolver_iterator<InternetProtocol>()`. Otherwise returns
-      `ip::basic_resolver_iterator<InternetProtocol>()`.
-    ]
-  ]
-  [
-    [``
-      a.async_resolve(b, e, h);
-    ``]
-    []
-    [
-      Initiates an asynchronous resolve operation that is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      If the operation completes successfully, the `ResolveHandler` object `h`
-      shall be invoked with an iterator object `i` such that the condition `i
-      != ip::basic_resolver_iterator<InternetProtocol>()` holds. Otherwise it
-      is invoked with `ip::basic_resolver_iterator<InternetProtocol>()`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/SeqPacketSocketService.qbk b/doc/requirements/SeqPacketSocketService.qbk
deleted file mode 100644
index 5844b4e8e0..0000000000
--- a/doc/requirements/SeqPacketSocketService.qbk
+++ /dev/null
@@ -1,127 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:SeqPacketSocketService Sequenced packet socket service requirements]
-
-A sequenced packet socket service must meet the requirements for a [link
-boost_asio.reference.SocketService socket service], as well as the additional
-requirements listed below.
-
-In the table below, `X` denotes a stream socket service class, `a` denotes a
-value of type `X`, `b` denotes a value of type `X::implementation_type`, `ec`
-denotes a value of type `error_code`, `f` denotes a value of type
-`socket_base::message_flags`, `g` denotes an lvalue of type
-`socket_base::message_flags`, `mb` denotes a value satisfying [link
-boost_asio.reference.MutableBufferSequence mutable buffer sequence] requirements,
-`rh` denotes a value meeting [link boost_asio.reference.ReadHandler `ReadHandler`]
-requirements, `cb` denotes a value satisfying [link
-boost_asio.reference.ConstBufferSequence constant buffer sequence] requirements, and
-`wh` denotes a value meeting [link boost_asio.reference.WriteHandler `WriteHandler`]
-requirements.
-
-[table StreamSocketService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.receive(b, mb, f, g, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a connected socket `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, sets `g` to the flags associated with the received data,
-      and returns the number of bytes read. Otherwise, sets `g` to `0` and
-      returns `0`.
-    ]
-  ]
-  [
-    [`a.async_receive(b, mb, f, g, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a connected socket `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, sets `g` to the flags associated
-      with the received data, then invokes the `ReadHandler` object `rh` with
-      the number of bytes transferred. Otherwise, sets `g` to `0` and invokes
-      `rh` with `0` bytes transferred.
-    ]
-  ]
-  [
-    [`a.send(b, cb, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a connected socket `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-    ]
-  ]
-  [
-    [`a.async_send(b, cb, f, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a connected socket `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/SerialPortService.qbk b/doc/requirements/SerialPortService.qbk
deleted file mode 100644
index 4cff7c1b03..0000000000
--- a/doc/requirements/SerialPortService.qbk
+++ /dev/null
@@ -1,301 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:SerialPortService Serial port service requirements]
-
-A serial port service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service] with support for movability,
-as well as the additional requirements listed below.
-
-In the table below, `X` denotes a serial port service class, `a` and `ao` denote
-values of type `X`, `d` denotes a serial port device name of type `std::string`,
-`b` and `c` denote values of type `X::implementation_type`, `n` denotes a value
-of type `X::native_handle_type`, `ec` denotes a value of type `error_code`, `s`
-denotes a value meeting [link boost_asio.reference.SettableSerialPortOption
-`SettableSerialPortOption`] requirements, `g` denotes a value meeting [link
-boost_asio.reference.GettableSerialPortOption `GettableSerialPortOption`]
-requirements, `mb` denotes a value satisfying [link
-boost_asio.reference.MutableBufferSequence mutable buffer sequence] requirements,
-`rh` denotes a value meeting [link boost_asio.reference.ReadHandler `ReadHandler`]
-requirements, `cb` denotes a value satisfying [link
-boost_asio.reference.ConstBufferSequence constant buffer sequence] requirements, and
-`wh` denotes a value meeting [link boost_asio.reference.WriteHandler `WriteHandler`]
-requirements. and `u` and `v` denote identifiers.
-
-[table SerialPortService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`X::native_handle_type`]
-    []
-    [
-      The implementation-defined native representation of a serial port. Must
-      satisfy the requirements of `CopyConstructible` types (C++ Std, 20.1.3),
-      and the requirements of `Assignable` types (C++ Std, 23.1).
-    ]
-  ]
-  [
-    [`a.construct(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous operations, as if by calling
-      `a.close(b, ec)`.
-    ]
-  ]
-  [
-    [``
-      a.move_construct(b, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      The underlying native representation is moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.move_assign(b, ao, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      Implicitly cancels asynchronous operations associated with `b`, as if by
-      calling `a.close(b, ec)`. Then the underlying native representation is
-      moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      const std::string& u = d;
-      a.open(b, u, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.assign(b, n, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.is_open(b);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.is_open(v);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.close(b, ec);
-    ``]
-    [`error_code`]
-    [
-      If `a.is_open()` is true, causes any outstanding asynchronous operations
-      to complete as soon as possible. Handlers for cancelled operations shall
-      be passed the error code `error::operation_aborted`.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.native_handle(b);
-    ``]
-    [`X::native_handle_type`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.\n
-      Causes any outstanding asynchronous operations to complete as soon as
-      possible. Handlers for cancelled operations shall be passed the error
-      code `error::operation_aborted`.
-    ]
-  ]
-  [
-    [``
-      a.set_option(b, s, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.get_option(b, g, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.get_option(v, g, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.send_break(b, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [`a.read_some(b, mb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a serial port `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `mb` is `0`, the
-      function shall return `0` immediately.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.
-    ]
-  ]
-  [
-    [`a.async_read_some(b, mb, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a serial port `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `mb` is `0`, the asynchronous read operation shall complete immediately
-      and pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.write_some(b, cb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a serial port `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `cb` is `0`, the
-      function shall return `0` immediately.
-    ]
-  ]
-  [
-    [`a.async_write_some(b, cb, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a serial port `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `cb` is `0`, the asynchronous operation shall complete immediately and
-      pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/Service.qbk b/doc/requirements/Service.qbk
index c27fbdaf9d..ceda250a39 100644
--- a/doc/requirements/Service.qbk
+++ b/doc/requirements/Service.qbk
@@ -7,27 +7,34 @@
 
 [section:Service Service requirements]
 
-A class is a service if it is publicly derived from another service, or if it
-is a class derived from `io_service::service` and contains a
-publicly-accessible declaration as follows:
+A class is a ['service] if it is publicly and unambiguously derived from
+`execution_context::service`, or if it is publicly and unambiguously derived
+from another service. For a service `S`, `S::key_type` shall be valid and
+denote a type (C++Std [temp.deduct]), `is_base_of_v<typename S::key_type, S>`
+shall be `true`, and `S` shall satisfy the `Destructible` requirements (C++Std
+[destructible]).
 
-  static io_service::id id;
+The first parameter of all service constructors shall be an lvalue reference to
+`execution_context`. This parameter denotes the `execution_context` object that
+represents a set of services, of which the service object will be a member.
+[inline_note These constructors may be called by the `make_service` function.]
 
-All services define a one-argument constructor that takes a reference to the
-`io_service` object that owns the service. This constructor is /explicit/,
-preventing its participation in automatic conversions. For example:
+A service shall provide an explicit constructor with a single parameter of
+lvalue reference to `execution_context`. [inline_note This constructor may be
+called by the `use_service` function.]
 
-  class my_service : public io_service::service
+  class my_service : public execution_context::service
   {
   public:
-    static io_service::id id;
-    explicit my_service(io_service& ios);
+    typedef my_service key_type;
+    explicit my_service(execution_context& ctx);
+    my_service(execution_context& ctx, int some_value);
   private:
-    virtual void shutdown_service();
+    virtual void shutdown() noexcept override;
     ...
   };
 
-A service's `shutdown_service` member function must cause all copies of
-user-defined handler objects that are held by the service to be destroyed.
+A service's `shutdown` member function shall destroy all copies of user-defined
+function objects that are held by the service.
 
 [endsect]
diff --git a/doc/requirements/SettableSocketOption.qbk b/doc/requirements/SettableSocketOption.qbk
index 5fdae14a8f..5dec280e4d 100644
--- a/doc/requirements/SettableSocketOption.qbk
+++ b/doc/requirements/SettableSocketOption.qbk
@@ -7,14 +7,17 @@
 
 [section:SettableSocketOption Settable socket option requirements]
 
-In the table below, `X` denotes a socket option class, `a` denotes a value of
-`X`, `p` denotes a value that meets the [link boost_asio.reference.Protocol
-protocol] requirements, and `u` denotes an identifier.
+A type `X` meets the `SettableSocketOption` requirements if it satisfies the
+requirements listed below.
 
-[table SettableSocketOption requirements
+In the table below, `a` denotes a (possibly const) value of type `X`, `p`
+denotes a (possibly const) value that meets the [link boost_asio.reference.Protocol
+`Protocol`] requirements, and `u` denotes an identifier.
+
+[table SettableSocketOption requirements for extensible implementations
   [[expression] [type] [assertion/note\npre/post-conditions]]
   [
-    [`a.level(p);`]
+    [`a.level(p)`]
     [`int`]
     [
       Returns a value suitable for passing as the /level/ argument to __POSIX__
@@ -22,7 +25,7 @@ protocol] requirements, and `u` denotes an identifier.
     ]
   ]
   [
-    [`a.name(p);`]
+    [`a.name(p)`]
     [`int`]
     [
       Returns a value suitable for passing as the /option_name/ argument to
@@ -30,16 +33,15 @@ protocol] requirements, and `u` denotes an identifier.
     ]
   ]
   [
-    [`const X& u = a;
-      u.data(p);`]
-    [a pointer, convertible to `const void*`]
+    [`a.data(p)`]
+    [`const void*`]
     [
       Returns a pointer suitable for passing as the /option_value/ argument to
       __POSIX__ __setsockopt__ (or equivalent).
     ]
   ]
   [
-    [`a.size(p);`]
+    [`a.size(p)`]
     [`size_t`]
     [
       Returns a value suitable for passing as the /option_len/ argument to
diff --git a/doc/requirements/ShutdownHandler.qbk b/doc/requirements/ShutdownHandler.qbk
index 1e37b9cfae..f773ed1409 100644
--- a/doc/requirements/ShutdownHandler.qbk
+++ b/doc/requirements/ShutdownHandler.qbk
@@ -35,7 +35,29 @@ A shutdown handler function object:
     ...
   };
 
-A non-static class member function adapted to a shutdown handler using `bind()`:
+A lambda as a shutdown handler:
+
+  ssl_stream.async_shutdown(...,
+      [](const boost::system::error_code& ec)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a shutdown handler using
+`std::bind()`:
+
+  void my_class::shutdown_handler(
+      const boost::system::error_code& ec)
+  {
+    ...
+  }
+  ...
+  ssl_stream.async_shutdown(
+      std::bind(&my_class::shutdown_handler,
+        this, std::placeholders::_1));
+
+A non-static class member function adapted to a shutdown handler using
+`boost::bind()`:
 
   void my_class::shutdown_handler(
       const boost::system::error_code& ec)
diff --git a/doc/requirements/SignalHandler.qbk b/doc/requirements/SignalHandler.qbk
index 74d8b850fd..74b67645c5 100644
--- a/doc/requirements/SignalHandler.qbk
+++ b/doc/requirements/SignalHandler.qbk
@@ -37,7 +37,32 @@ A signal handler function object:
     ...
   };
 
-A non-static class member function adapted to a signal handler using `bind()`:
+A lambda as a signal handler:
+
+  my_signal_set.async_wait(
+      [](const boost::system::error_code& ec,
+        int signal_number)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a signal handler using
+`std::bind()`:
+
+  void my_class::signal_handler(
+      const boost::system::error_code& ec,
+      int signal_number)
+  {
+    ...
+  }
+  ...
+  my_signal_set.async_wait(
+      std::bind(&my_class::signal_handler,
+        this, std::placeholders::_1,
+        std::placeholders::_2));
+
+A non-static class member function adapted to a signal handler using
+`boost::bind()`:
 
   void my_class::signal_handler(
       const boost::system::error_code& ec,
diff --git a/doc/requirements/SignalSetService.qbk b/doc/requirements/SignalSetService.qbk
deleted file mode 100644
index f649accec8..0000000000
--- a/doc/requirements/SignalSetService.qbk
+++ /dev/null
@@ -1,91 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:SignalSetService Signal set service requirements]
-
-A signal set service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service], as well as the
-additional requirements listed below.
-
-In the table below, `X` denotes a signal set service class, `a` denotes a value
-of type `X`, `b` denotes a value of type `X::implementation_type`, `ec` denotes
-a value of type `error_code`, `n` denotes a value of type `int`, and `sh`
-denotes a value meeting [link boost_asio.reference.SignalHandler `SignalHandler`]
-requirements.
-
-[table SignalSetService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.construct(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements.\n
-    ]
-  ]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly clears the registered signals as if by calling
-      `a.clear(b, ec)`, then implicitly cancels outstanding asynchronous
-      operations as if by calling `a.cancel(b, ec)`.
-    ]
-  ]
-  [
-    [``
-      a.add(b, n, ec);
-    ``]
-    [`error_code`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.remove(b, n, ec);
-    ``]
-    [`error_code`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.clear(b, ec);
-    ``]
-    [`error_code`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, ec);
-    ``]
-    [`error_code`]
-    [
-    ]
-  ]
-  [
-    [`a.async_wait(b, sh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to wait for the delivery of one of the
-      signals registered for the signal set `b`. The operation is performed via
-      the `io_service` object `a.get_io_service()` and behaves according to
-      [link boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      If the operation completes successfully, the `SignalHandler` object
-      `sh` is invoked with the number identifying the delivered signal. Otherwise
-      it is invoked with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/SocketAcceptorService.qbk b/doc/requirements/SocketAcceptorService.qbk
deleted file mode 100644
index 3ba995cf93..0000000000
--- a/doc/requirements/SocketAcceptorService.qbk
+++ /dev/null
@@ -1,270 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:SocketAcceptorService Socket acceptor service requirements]
-
-A socket acceptor service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service], as well as the
-additional requirements listed below.
-
-In the table below, `X` denotes a socket acceptor service class for protocol
-[link boost_asio.reference.Protocol `Protocol`], `a` and `ao` denote values of type
-`X`, `b` and `c` denote values of type `X::implementation_type`, `p` denotes a
-value of type `Protocol`, `n` denotes a value of type `X::native_handle_type`,
-`e` denotes a value of type `Protocol::endpoint`, `ec` denotes a value of type
-`error_code`, `s` denotes a value meeting [link
-boost_asio.reference.SettableSocketOption `SettableSocketOption`] requirements, `g`
-denotes a value meeting [link boost_asio.reference.GettableSocketOption
-`GettableSocketOption`] requirements, `i` denotes a value meeting [link
-boost_asio.reference.IoControlCommand `IoControlCommand`] requirements, `k` denotes a
-value of type `basic_socket<Protocol, SocketService>` where `SocketService` is
-a type meeting [link boost_asio.reference.SocketService socket service] requirements,
-`ah` denotes a value meeting [link boost_asio.reference.AcceptHandler
-`AcceptHandler`] requirements, and `u` and `v` denote identifiers.
-
-[table SocketAcceptorService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`X::native_handle_type`]
-    []
-    [
-      The implementation-defined native representation of a socket acceptor.
-      Must satisfy the requirements of `CopyConstructible` types (C++ Std,
-      20.1.3), and the requirements of `Assignable` types (C++ Std, 23.1).
-    ]
-  ]
-  [
-    [`a.construct(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous operations, as if by calling
-      `a.close(b, ec)`.
-    ]
-  ]
-  [
-    [``
-      a.move_construct(b, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      The underlying native representation is moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.move_assign(b, ao, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      Implicitly cancels asynchronous operations associated with `b`, as if by
-      calling `a.close(b, ec)`. Then the underlying native representation is
-      moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.open(b, p, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.assign(b, p, n, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.is_open(b);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.is_open(v);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.close(b, ec);
-    ``]
-    [`error_code`]
-    [
-      If `a.is_open()` is true, causes any outstanding asynchronous operations
-      to complete as soon as possible. Handlers for cancelled operations shall
-      be passed the error code `error::operation_aborted`.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.native_handle(b);
-    ``]
-    [`X::native_handle_type`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.\n
-      Causes any outstanding asynchronous operations to complete as soon as
-      possible. Handlers for cancelled operations shall be passed the error
-      code `error::operation_aborted`.
-    ]
-  ]
-  [
-    [``
-      a.set_option(b, s, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.get_option(b, g, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.get_option(v, g, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.io_control(b, i, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.bind(b, u, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.local_endpoint(b, ec);
-    ``]
-    [`Protocol::endpoint`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.local_endpoint(v, ec);
-    ``]
-    [`Protocol::endpoint`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.accept(b, k, &e, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b) && !k.is_open()`.\n
-      post: `k.is_open()`
-    ]
-  ]
-  [
-    [``
-      a.accept(b, k, 0, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b) && !k.is_open()`.\n
-      post: `k.is_open()`
-    ]
-  ]
-  [
-    [``
-      a.async_accept(b, k, &e, ah);
-    ``]
-    []
-    [
-      pre: `a.is_open(b) && !k.is_open()`.\n
-      Initiates an asynchronous accept operation that is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n\n
-      The program must ensure the objects `k` and `e` are valid until the
-      handler for the asynchronous operation is invoked.
-    ]
-  ]
-  [
-    [``
-      a.async_accept(b, k, 0, ah);
-    ``]
-    []
-    [
-      pre: `a.is_open(b) && !k.is_open()`.\n
-      Initiates an asynchronous accept operation that is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n\n
-      The program must ensure the object `k` is valid until the handler for the
-      asynchronous operation is invoked.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/SocketService.qbk b/doc/requirements/SocketService.qbk
deleted file mode 100644
index f5d8255a45..0000000000
--- a/doc/requirements/SocketService.qbk
+++ /dev/null
@@ -1,312 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:SocketService Socket service requirements]
-
-A socket service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service] with support for movability,
-as well as the  additional requirements listed below.
-
-In the table below, `X` denotes a socket service class for protocol [link
-boost_asio.reference.Protocol `Protocol`], `a` and `ao` denote values of type `X`,
-`b` and `c` denote values of type `X::implementation_type`, `p` denotes a value
-of type `Protocol`, `n` denotes a value of type `X::native_handle_type`, `e`
-denotes a value of type `Protocol::endpoint`, `ec` denotes a value of type
-`error_code`, `s` denotes a value meeting [link
-boost_asio.reference.SettableSocketOption `SettableSocketOption`] requirements, `g`
-denotes a value meeting [link boost_asio.reference.GettableSocketOption
-`GettableSocketOption`] requirements, `i` denotes a value meeting [link
-boost_asio.reference.IoControlCommand `IoControlCommand`] requirements, `h`
-denotes a value of type `socket_base::shutdown_type`, `ch` denotes a value
-meeting [link boost_asio.reference.ConnectHandler `ConnectHandler`]
-requirements, and `u` and `v` denote identifiers.
-
-[table SocketService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`X::native_handle_type`]
-    []
-    [
-      The implementation-defined native representation of a socket. Must
-      satisfy the requirements of `CopyConstructible` types (C++ Std, 20.1.3),
-      and the requirements of `Assignable` types (C++ Std, 23.1).
-    ]
-  ]
-  [
-    [`a.construct(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous operations, as if by calling
-      `a.close(b, ec)`.
-    ]
-  ]
-  [
-    [``
-      a.move_construct(b, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      The underlying native representation is moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.move_assign(b, ao, c);
-    ``]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService] requirements.
-      Implicitly cancels asynchronous operations associated with `b`, as if by
-      calling `a.close(b, ec)`. Then the underlying native representation is
-      moved from `c` to `b`.
-    ]
-  ]
-  [
-    [``
-      a.open(b, p, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.assign(b, p, n, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `!a.is_open(b)`.\n
-      post: `!!ec || a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.is_open(b);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.is_open(v);
-    ``]
-    [`bool`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.close(b, ec);
-    ``]
-    [`error_code`]
-    [
-      If `a.is_open()` is true, causes any outstanding asynchronous operations
-      to complete as soon as possible. Handlers for cancelled operations shall
-      be passed the error code `error::operation_aborted`.\n
-      post: `!a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.native_handle(b);
-    ``]
-    [`X::native_handle_type`]
-    [
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.\n
-      Causes any outstanding asynchronous operations to complete as soon as
-      possible. Handlers for cancelled operations shall be passed the error
-      code `error::operation_aborted`.
-    ]
-  ]
-  [
-    [``
-      a.set_option(b, s, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.get_option(b, g, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.get_option(v, g, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.io_control(b, i, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.at_mark(b, ec);
-    ``]
-    [`bool`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.at_mark(v, ec);
-    ``]
-    [`bool`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.available(b, ec);
-    ``]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.available(v, ec);
-    ``]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.bind(b, u, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.shutdown(b, h, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.local_endpoint(b, ec);
-    ``]
-    [`Protocol::endpoint`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.local_endpoint(v, ec);
-    ``]
-    [`Protocol::endpoint`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      a.remote_endpoint(b, ec);
-    ``]
-    [`Protocol::endpoint`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const X& u = a;
-      const X::implementation_type& v = b;
-      u.remote_endpoint(v, ec);
-    ``]
-    [`Protocol::endpoint`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.connect(b, u, ec);
-    ``]
-    [`error_code`]
-    [
-      pre: `a.is_open(b)`.
-    ]
-  ]
-  [
-    [``
-      const typename Protocol::endpoint& u = e;
-      a.async_connect(b, u, ch);
-    ``]
-    []
-    [
-      pre: `a.is_open(b)`.\n
-      Initiates an asynchronous connect operation that is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/StreamDescriptorService.qbk b/doc/requirements/StreamDescriptorService.qbk
deleted file mode 100644
index 2a9803473f..0000000000
--- a/doc/requirements/StreamDescriptorService.qbk
+++ /dev/null
@@ -1,138 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:StreamDescriptorService Stream descriptor service requirements]
-
-A stream descriptor service must meet the requirements for a [link
-boost_asio.reference.DescriptorService descriptor service], as well as the additional
-requirements listed below.
-
-In the table below, `X` denotes a stream descriptor service class, `a` denotes
-a value of type `X`, `b` denotes a value of type `X::implementation_type`, `ec`
-denotes a value of type `error_code`, `mb` denotes a value satisfying [link
-boost_asio.reference.MutableBufferSequence mutable buffer sequence] requirements,
-`rh` denotes a value meeting [link boost_asio.reference.ReadHandler `ReadHandler`]
-requirements, `cb` denotes a value satisfying [link
-boost_asio.reference.ConstBufferSequence constant buffer sequence] requirements, and
-`wh` denotes a value meeting [link boost_asio.reference.WriteHandler `WriteHandler`]
-requirements.
-
-[table StreamDescriptorService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.read_some(b, mb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a descriptor `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `mb` is `0`, the
-      function shall return `0` immediately.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.
-    ]
-  ]
-  [
-    [`a.async_read_some(b, mb, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a descriptor `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `mb` is `0`, the asynchronous read operation shall complete immediately
-      and pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.write_some(b, cb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a descriptor `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `cb` is `0`, the
-      function shall return `0` immediately.
-    ]
-  ]
-  [
-    [`a.async_write_some(b, cb, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a descriptor `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `cb` is `0`, the asynchronous operation shall complete immediately and
-      pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/StreamHandleService.qbk b/doc/requirements/StreamHandleService.qbk
deleted file mode 100644
index 3ad72abc90..0000000000
--- a/doc/requirements/StreamHandleService.qbk
+++ /dev/null
@@ -1,138 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:StreamHandleService Stream handle service requirements]
-
-A stream handle service must meet the requirements for a [link
-boost_asio.reference.HandleService handle service], as well as the additional
-requirements listed below.
-
-In the table below, `X` denotes a stream handle service class, `a` denotes
-a value of type `X`, `b` denotes a value of type `X::implementation_type`, `ec`
-denotes a value of type `error_code`, `mb` denotes a value satisfying [link
-boost_asio.reference.MutableBufferSequence mutable buffer sequence] requirements,
-`rh` denotes a value meeting [link boost_asio.reference.ReadHandler `ReadHandler`]
-requirements, `cb` denotes a value satisfying [link
-boost_asio.reference.ConstBufferSequence constant buffer sequence] requirements, and
-`wh` denotes a value meeting [link boost_asio.reference.WriteHandler `WriteHandler`]
-requirements.
-
-[table StreamHandleService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.read_some(b, mb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a handle `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `mb` is `0`, the
-      function shall return `0` immediately.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.
-    ]
-  ]
-  [
-    [`a.async_read_some(b, mb, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a handle `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `mb` is `0`, the asynchronous read operation shall complete immediately
-      and pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.write_some(b, cb, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a handle `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `cb` is `0`, the
-      function shall return `0` immediately.
-    ]
-  ]
-  [
-    [`a.async_write_some(b, cb, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a handle `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `cb` is `0`, the asynchronous operation shall complete immediately and
-      pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/StreamSocketService.qbk b/doc/requirements/StreamSocketService.qbk
deleted file mode 100644
index 4f9efc64f8..0000000000
--- a/doc/requirements/StreamSocketService.qbk
+++ /dev/null
@@ -1,139 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:StreamSocketService Stream socket service requirements]
-
-A stream socket service must meet the requirements for a [link
-boost_asio.reference.SocketService socket service], as well as the additional
-requirements listed below.
-
-In the table below, `X` denotes a stream socket service class, `a` denotes a
-value of type `X`, `b` denotes a value of type `X::implementation_type`, `ec`
-denotes a value of type `error_code`, `f` denotes a value of type
-`socket_base::message_flags`, `mb` denotes a value satisfying [link
-boost_asio.reference.MutableBufferSequence mutable buffer sequence]
-requirements, `rh` denotes a value meeting [link
-boost_asio.reference.ReadHandler `ReadHandler`] requirements, `cb` denotes a
-value satisfying [link boost_asio.reference.ConstBufferSequence constant
-buffer sequence] requirements, and `wh` denotes a value meeting [link
-boost_asio.reference.WriteHandler `WriteHandler`] requirements.
-
-[table StreamSocketService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.receive(b, mb, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Reads one or more bytes of data from a connected socket `b`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes read. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `mb` is `0`, the
-      function shall return `0` immediately.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.
-    ]
-  ]
-  [
-    [`a.async_receive(b, mb, f, rh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to read one or more bytes of data
-      from a connected socket `b`. The operation is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The operation shall always fill a buffer in the sequence
-      completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `mb` until such
-      time as the read operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `mb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `mb` is `0`, the asynchronous read operation shall complete immediately
-      and pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes due to graceful connection closure by the
-      peer, the operation shall fail with `error::eof`.\n
-      \n
-      If the operation completes successfully, the `ReadHandler` object
-      `rh` is invoked with the number of bytes transferred. Otherwise it is
-      invoked with `0`.
-    ]
-  ]
-  [
-    [`a.send(b, cb, f, ec);`]
-    [`size_t`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Writes one or more bytes of data to a connected socket `b`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      If successful, returns the number of bytes written. Otherwise returns `0`.
-      If the total size of all buffers in the sequence `cb` is `0`, the
-      function shall return `0` immediately.
-    ]
-  ]
-  [
-    [`a.async_send(b, cb, f, wh);`]
-    [`void`]
-    [
-      pre: `a.is_open(b)`.\n
-      \n
-      Initiates an asynchronous operation to write one or more bytes of data to
-      a connected socket `b`. The operation is performed via the `io_service`
-      object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The operation shall always write a buffer in the
-      sequence completely before proceeding to the next.\n
-      \n
-      The implementation shall maintain one or more copies of `cb` until such
-      time as the write operation no longer requires access to the memory
-      specified by the buffers in the sequence. The program must ensure the
-      memory is valid until:\n
-      \n
-      [mdash] the last copy of `cb` is destroyed, or\n
-      \n
-      [mdash] the handler for the asynchronous operation is invoked,\n
-      \n
-      whichever comes first. If the total size of all buffers in the sequence
-      `cb` is `0`, the asynchronous operation shall complete immediately and
-      pass `0` as the argument to the handler that specifies the number of
-      bytes read.\n
-      \n
-      If the operation completes successfully, the `WriteHandler` object `wh`
-      is invoked with the number of bytes transferred. Otherwise it is invoked
-      with `0`.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/SyncReadStream.qbk b/doc/requirements/SyncReadStream.qbk
index ad99b462ed..3b11b8a505 100644
--- a/doc/requirements/SyncReadStream.qbk
+++ b/doc/requirements/SyncReadStream.qbk
@@ -7,40 +7,33 @@
 
 [section:SyncReadStream Buffer-oriented synchronous read stream requirements]
 
-In the table below, `a` denotes a synchronous read stream object, `mb` denotes
-an object satisfying [link boost_asio.reference.MutableBufferSequence
-mutable buffer sequence] requirements, and `ec` denotes an object of type
+A type `X` meets the `SyncReadStream` requirements if it satisfies the
+requirements listed below.
+
+In the table below, `a` denotes a value of type `X`, `mb` denotes a (possibly
+const) value satisfying the [link boost_asio.reference.MutableBufferSequence
+`MutableBufferSequence`] requirements, and `ec` denotes an object of type
 `error_code`.
 
-[table Buffer-oriented synchronous read stream requirements
+[table SyncReadStream requirements
   [[operation] [type] [semantics, pre/post-conditions]]
   [
-    [`a.read_some(mb);`]
-    [`size_t`]
-    [Equivalent to:
-     ``
-       error_code ec;
-       size_t s = a.read_some(mb, ec);
-       if (ec) throw system_error(ec);
-       return s;
-     ``]
-  ]
-  [
-    [`a.read_some(mb, ec);`]
+    [`a.read_some(mb)`\n
+     `a.read_some(mb,ec)`]
     [`size_t`]
     [
-      Reads one or more bytes of data from the stream `a`.\n
-      \n
-      The mutable buffer sequence `mb` specifies memory where the data should
-      be placed. The `read_some` operation shall always fill a buffer in the
-      sequence completely before proceeding to the next.\n
+      Meets the requirements for a [link boost_asio.reference.read_write_operations
+      read operation].\n
       \n
-      If successful, returns the number of bytes read and sets `ec` such that
-      `!ec` is true. If an error occurred, returns `0` and sets `ec` such that
-      `!!ec` is true.\n
+      If `buffer_size(mb) > 0`, reads one or more bytes of data from the stream
+      `a` into the buffer sequence `mb`. If successful, sets `ec` such that
+      `!ec` is `true`, and returns the number of bytes read. If an error
+      occurred, sets `ec` such that `!!ec` is `true`, and returns 0. If all
+      data has been read from the stream, and the stream performed an orderly
+      shutdown, sets `ec` to `stream_errc::eof` and returns 0.\n
       \n
-      If the total size of all buffers in the sequence `mb` is `0`, the
-      function shall return `0` immediately.
+      If `buffer_size(mb) == 0`, the operation shall not block. Sets `ec` such
+      that `!ec` is `true`, and returns 0.
     ]
   ]
 ]
diff --git a/doc/requirements/SyncWriteStream.qbk b/doc/requirements/SyncWriteStream.qbk
index 5c30d255e2..18478ab23d 100644
--- a/doc/requirements/SyncWriteStream.qbk
+++ b/doc/requirements/SyncWriteStream.qbk
@@ -7,39 +7,31 @@
 
 [section:SyncWriteStream Buffer-oriented synchronous write stream requirements]
 
-In the table below, `a` denotes a synchronous write stream object, `cb` denotes
-an object satisfying [link boost_asio.reference.ConstBufferSequence constant
-buffer sequence] requirements, and `ec` denotes an object of type `error_code`.
+A type `X` meets the `SyncWriteStream` requirements if it satisfies the
+requirements listed below.
 
-[table Buffer-oriented synchronous write stream requirements
+In the table below, `a` denotes a value of type `X`, `cb` denotes a (possibly
+const) value satisfying the [link boost_asio.reference.ConstBufferSequence
+`ConstBufferSequence`] requirements, and `ec` denotes an object of type
+`error_code`.
+
+[table SyncWriteStream requirements
   [[operation] [type] [semantics, pre/post-conditions]]
   [
-    [`a.write_some(cb);`]
-    [`size_t`]
-    [Equivalent to:
-     ``
-       error_code ec;
-       size_t s = a.write_some(cb, ec);
-       if (ec) throw system_error(ec);
-       return s;
-     ``]
-  ]
-  [
-    [`a.write_some(cb, ec);`]
+    [`a.write_some(cb)`\n
+     `a.write_some(cb,ec)`]
     [`size_t`]
     [
-      Writes one or more bytes of data to the stream `a`.\n
-      \n
-      The constant buffer sequence `cb` specifies memory where the data to be
-      written is located. The `write_some` operation shall always write a
-      buffer in the sequence completely before proceeding to the next.\n
+      Meets the requirements for a [link boost_asio.reference.read_write_operations
+      write operation].\n
       \n
-      If successful, returns the number of bytes written and sets `ec` such
-      that `!ec` is true. If an error occurred, returns `0` and sets `ec` such
-      that `!!ec` is true.\n
+      If `buffer_size(cb) > 0`, writes one or more bytes of data to the stream
+      `a` from the buffer sequence `cb`. If successful, sets `ec` such that
+      `!ec` is `true`, and returns the number of bytes written. If an error
+      occurred, sets `ec` such that `!!ec` is `true`, and returns 0.\n
       \n
-      If the total size of all buffers in the sequence `cb` is `0`, the
-      function shall return `0` immediately.
+      If `buffer_size(cb) == 0`, the operation shall not block. Sets `ec` such
+      that `!ec` is `true`, and returns 0.
     ]
   ]
 ]
diff --git a/doc/requirements/TimerService.qbk b/doc/requirements/TimerService.qbk
deleted file mode 100644
index 47f8e16259..0000000000
--- a/doc/requirements/TimerService.qbk
+++ /dev/null
@@ -1,105 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:TimerService Timer service requirements]
-
-A timer service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service], as well as the
-additional requirements listed below.
-
-In the table below, `X` denotes a timer service class for time type `Time` and
-traits type `TimeTraits`, `a` denotes a value of type `X`, `b` denotes a value
-of type `X::implementation_type`, `t` denotes a value of type `Time`, `d`
-denotes a value of type `TimeTraits::duration_type`, `e` denotes a value of
-type `error_code`, and `h` denotes a value meeting [link
-boost_asio.reference.WaitHandler `WaitHandler`] requirements.
-
-[table TimerService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous wait operations, as if by
-      calling `a.cancel(b, e)`.
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, e);
-    ``]
-    [`size_t`]
-    [
-      Causes any outstanding asynchronous wait operations to complete as soon
-      as possible. Handlers for cancelled operations shall be passed the error
-      code `error::operation_aborted`. Sets `e` to indicate success or failure.
-      Returns the number of operations that were cancelled.
-    ]
-  ]
-  [
-    [`a.expires_at(b);`]
-    [`Time`]
-    []
-  ]
-  [
-    [``
-      a.expires_at(b, t, e);
-    ``]
-    [`size_t`]
-    [
-      Implicitly cancels asynchronous wait operations, as if by calling
-      `a.cancel(b, e)`. Returns the number of operations that were cancelled.\n
-      post: `a.expires_at(b) == t`.
-    ]
-  ]
-  [
-    [`a.expires_from_now(b);`]
-    [`TimeTraits::duration_type`]
-    [
-      Returns a value equivalent to `TimeTraits::subtract(a.expires_at(b),
-      TimeTraits::now())`.
-    ]
-  ]
-  [
-    [``
-      a.expires_from_now(b, d, e);
-    ``]
-    [`size_t`]
-    [
-      Equivalent to `a.expires_at(b, TimeTraits::add(TimeTraits::now(), d), e)`.
-    ]
-  ]
-  [
-    [``
-      a.wait(b, e);
-    ``]
-    [`error_code`]
-    [
-      Sets `e` to indicate success or failure. Returns `e`.\n
-      post: `!!e || !TimeTraits::lt(TimeTraits::now(), a.expires_at(b))`.
-    ]
-  ]
-  [
-    [``
-      a.async_wait(b, h);
-    ``]
-    []
-    [
-      Initiates an asynchronous wait operation that is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The handler shall be posted for execution only if the condition
-      `!!ec || !TimeTraits::lt(TimeTraits::now(), a.expires_at(b))`
-      holds, where `ec` is the error code to be passed to the handler.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/WaitHandler.qbk b/doc/requirements/WaitHandler.qbk
index 9bbf31f5c9..e8cfd37451 100644
--- a/doc/requirements/WaitHandler.qbk
+++ b/doc/requirements/WaitHandler.qbk
@@ -35,7 +35,29 @@ A wait handler function object:
     ...
   };
 
-A non-static class member function adapted to a wait handler using `bind()`:
+A lambda as a wait handler:
+
+  socket.async_wait(...,
+      [](const boost::system::error_code& ec)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a wait handler using
+`std::bind()`:
+
+  void my_class::wait_handler(
+      const boost::system::error_code& ec)
+  {
+    ...
+  }
+  ...
+  socket.async_wait(...,
+      std::bind(&my_class::wait_handler,
+        this, std::placeholders::_1));
+
+A non-static class member function adapted to a wait handler using
+`boost::bind()`:
 
   void my_class::wait_handler(
       const boost::system::error_code& ec)
diff --git a/doc/requirements/WaitTraits.qbk b/doc/requirements/WaitTraits.qbk
index c5cbad89c9..11e93d1f61 100644
--- a/doc/requirements/WaitTraits.qbk
+++ b/doc/requirements/WaitTraits.qbk
@@ -7,18 +7,44 @@
 
 [section:WaitTraits Wait traits requirements]
 
-In the table below, `X` denotes a wait traits class for clock type `Clock`,
-where `Clock` meets the C++11 type requirements for a clock, and `d` denotes
-a value of type `Clock::duration`.
+The `basic_waitable_timer` template uses wait traits to allow programs to
+customize `wait` and `async_wait` behavior.
+[inline_note Possible uses of wait traits include:\n
+[mdash] To enable timers based on non-realtime clocks.\n
+[mdash] Determining how quickly wallclock-based timers respond to system time
+changes.\n
+[mdash] Correcting for errors or rounding timeouts to boundaries.\n
+[mdash] Preventing duration overflow. That is, a program may set a timer's
+expiry `e` to be `Clock::max()` (meaning never reached) or `Clock::min()`
+(meaning always in the past). As a result, computing the duration until timer
+expiry as `e - Clock::now()` may cause overflow.]
+
+For a type `Clock` meeting the `Clock` requirements (C++Std
+[time.clock.req]), a type `X` meets the `WaitTraits` requirements if it
+satisfies the requirements listed below.
+
+In the table below, `t` denotes a (possibly const) value of type
+`Clock::time_point`; and `d` denotes a (possibly const) value of type
+`Clock::duration`.
 
 [table WaitTraits requirements
   [[expression] [return type] [assertion/note\npre/post-condition]]
   [
-    [`X::to_wait_duration(d);`]
+    [`X::to_wait_duration(d)`]
+    [`Clock::duration`]
+    [
+      Returns a `Clock::duration` value to be used in a `wait` or `async_wait`
+      operation. [inline_note The return value is typically representative of
+      the duration `d`.]
+    ]
+  ]
+  [
+    [`X::to_wait_duration(t)`]
     [`Clock::duration`]
     [
-      Returns the maximum duration to be used for an individual,
-      implementation-defined wait operation.
+      Returns a `Clock::duration` value to be used in a `wait` or `async_wait`
+      operation. [inline_note The return value is typically representative of
+      the duration from `Clock::now()` until the time point `t`.]
     ]
   ]
 ]
diff --git a/doc/requirements/WaitableTimerService.qbk b/doc/requirements/WaitableTimerService.qbk
deleted file mode 100644
index 4df7af562e..0000000000
--- a/doc/requirements/WaitableTimerService.qbk
+++ /dev/null
@@ -1,104 +0,0 @@
-[/
- / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
-
-[section:WaitableTimerService Waitable timer service requirements]
-
-A waitable timer service must meet the requirements for an [link
-boost_asio.reference.IoObjectService I/O object service], as well as the
-additional requirements listed below.
-
-In the table below, `X` denotes a waitable timer service class for clock type
-`Clock`, where `Clock` meets the C++11 clock type requirements, `a` denotes a
-value of type `X`, `b` denotes a value of type `X::implementation_type`, `t`
-denotes a value of type `Clock::time_point`, `d` denotes a value of type
-`Clock::duration`, `e` denotes a value of type `error_code`, and `h` denotes a
-value meeting [link boost_asio.reference.WaitHandler `WaitHandler`] requirements.
-
-[table WaitableTimerService requirements
-  [[expression] [return type] [assertion/note\npre/post-condition]]
-  [
-    [`a.destroy(b);`]
-    []
-    [
-      From [link boost_asio.reference.IoObjectService IoObjectService]
-      requirements. Implicitly cancels asynchronous wait operations, as if by
-      calling `a.cancel(b, e)`.
-    ]
-  ]
-  [
-    [``
-      a.cancel(b, e);
-    ``]
-    [`size_t`]
-    [
-      Causes any outstanding asynchronous wait operations to complete as soon
-      as possible. Handlers for cancelled operations shall be passed the error
-      code `error::operation_aborted`. Sets `e` to indicate success or failure.
-      Returns the number of operations that were cancelled.
-    ]
-  ]
-  [
-    [`a.expires_at(b);`]
-    [`Clock::time_point`]
-    []
-  ]
-  [
-    [``
-      a.expires_at(b, t, e);
-    ``]
-    [`size_t`]
-    [
-      Implicitly cancels asynchronous wait operations, as if by calling
-      `a.cancel(b, e)`. Returns the number of operations that were cancelled.\n
-      post: `a.expires_at(b) == t`.
-    ]
-  ]
-  [
-    [`a.expires_from_now(b);`]
-    [`Clock::duration`]
-    [
-      Returns a value equivalent to `a.expires_at(b) - Clock::now()`.
-    ]
-  ]
-  [
-    [``
-      a.expires_from_now(b, d, e);
-    ``]
-    [`size_t`]
-    [
-      Equivalent to `a.expires_at(b, Clock::now() + d, e)`.
-    ]
-  ]
-  [
-    [``
-      a.wait(b, e);
-    ``]
-    [`error_code`]
-    [
-      Sets `e` to indicate success or failure. Returns `e`.\n
-      post: `!!e || !(Clock::now() < a.expires_at(b))`.
-    ]
-  ]
-  [
-    [``
-      a.async_wait(b, h);
-    ``]
-    []
-    [
-      Initiates an asynchronous wait operation that is performed via the
-      `io_service` object `a.get_io_service()` and behaves according to [link
-      boost_asio.reference.asynchronous_operations asynchronous operation]
-      requirements.\n
-      \n
-      The handler shall be posted for execution only if the condition
-      `!!ec || !(Clock::now() < a.expires_at(b))`
-      holds, where `ec` is the error code to be passed to the handler.
-    ]
-  ]
-]
-
-[endsect]
diff --git a/doc/requirements/WriteHandler.qbk b/doc/requirements/WriteHandler.qbk
index f5701fa8de..0f444065c4 100644
--- a/doc/requirements/WriteHandler.qbk
+++ b/doc/requirements/WriteHandler.qbk
@@ -37,7 +37,32 @@ A write handler function object:
     ...
   };
 
-A non-static class member function adapted to a write handler using `bind()`:
+A lambda as a write handler:
+
+  socket.async_write(...
+      [](const boost::system::error_code& ec,
+        std::size_t bytes_transferred)
+      {
+        ...
+      });
+
+A non-static class member function adapted to a write handler using
+`std::bind()`:
+
+  void my_class::write_handler(
+      const boost::system::error_code& ec,
+      std::size_t bytes_transferred)
+  {
+    ...
+  }
+  ...
+  socket.async_write(...,
+      std::bind(&my_class::write_handler,
+        this, std::placeholders::_1,
+        std::placeholders::_2));
+
+A non-static class member function adapted to a write handler using
+`boost::bind()`:
 
   void my_class::write_handler(
       const boost::system::error_code& ec,
diff --git a/doc/requirements/asynchronous_operations.qbk b/doc/requirements/asynchronous_operations.qbk
index 0d82016008..23866688da 100644
--- a/doc/requirements/asynchronous_operations.qbk
+++ b/doc/requirements/asynchronous_operations.qbk
@@ -7,211 +7,275 @@
 
 [section:asynchronous_operations Requirements on asynchronous operations]
 
-In Boost.Asio, an asynchronous operation is initiated by a function that is
-named with the prefix `async_`. These functions will be referred to as
-['initiating functions].
-
-All initiating functions in Boost.Asio take a function object meeting [link
-boost_asio.reference.Handler handler] requirements as the final parameter.
-These handlers accept as their first parameter an lvalue of type `const
-error_code`.
-
-Implementations of asynchronous operations in Boost.Asio may call the
-application programming interface (API) provided by the operating system. If
-such an operating system API call results in an error, the handler will be
-invoked with a `const error_code` lvalue that evaluates to true. Otherwise the
-handler will be invoked with a `const error_code` lvalue that evaluates to
-false.
-
-Unless otherwise noted, when the behaviour of an asynchronous operation is
-defined "as if" implemented by a __POSIX__ function, the handler will be
-invoked with a value of type `error_code` that corresponds to the failure
-condition described by __POSIX__ for that function, if any. Otherwise the
-handler will be invoked with an implementation-defined `error_code` value that
-reflects the operating system error.
-
-Asynchronous operations will not fail with an error condition that indicates
-interruption by a signal (__POSIX__ `EINTR`). Asynchronous operations will not
-fail with any error condition associated with non-blocking operations
-(__POSIX__ `EWOULDBLOCK`, `EAGAIN` or `EINPROGRESS`; __Windows__
-`WSAEWOULDBLOCK` or `WSAEINPROGRESS`).
-
-All asynchronous operations have an associated `io_service` object. Where the
-initiating function is a member function, the associated `io_service` is that
-returned by the `get_io_service()` member function on the same object. Where the
-initiating function is not a member function, the associated `io_service` is
-that returned by the `get_io_service()` member function of the first argument to
-the initiating function.
-
-Arguments to initiating functions will be treated as follows:
-
-[mdash] If the parameter is declared as a const reference or by-value, the
-program is not required to guarantee the validity of the argument after the
-initiating function completes. The implementation may make copies of the
-argument, and all copies will be destroyed no later than immediately after
-invocation of the handler.
-
-[mdash] If the parameter is declared as a non-const reference, const pointer or
-non-const pointer, the program must guarantee the validity of the argument
-until the handler is invoked.
-
-The library implementation is only permitted to make calls to an initiating
-function's arguments' copy constructors or destructors from a thread that
-satisfies one of the following conditions:
-
-[mdash] The thread is executing any member function of the associated
-`io_service` object.
-
-[mdash] The thread is executing the destructor of the associated `io_service`
-object.
+This section uses the names `Alloc1`, `Alloc2`, `alloc1`, `alloc2`, `Args`,
+`CompletionHandler`, `completion_handler`, `Executor1`, `Executor2`, `ex1`,
+`ex2`, `f`, [^['i]], [^['N]], `Signature`, `token`, [^T[sub ['i]]], [^t[sub
+['i]]], `work1`, and `work2` as placeholders for specifying the requirements
+below.
 
-[mdash] The thread is executing one of the `io_service` service access
-functions `use_service`, `add_service` or `has_service`, where the first
-argument is the associated `io_service` object.
-
-[mdash] The thread is executing any member function, constructor or destructor
-of an object of a class defined in this clause, where the object's
-`get_io_service()` member function returns the associated `io_service` object.
-
-[mdash] The thread is executing any function defined in this clause, where any
-argument to the function has an `get_io_service()` member function that returns
-the associated `io_service` object.
-
-[blurb Boost.Asio may use one or more hidden threads to emulate asynchronous
-functionality. The above requirements are intended to prevent these hidden
-threads from making calls to program code. This means that a program can, for
-example, use thread-unsafe reference counting in handler objects, provided the
-program ensures that all calls to an `io_service` and related objects occur
-from the one thread.]
-
-The `io_service` object associated with an asynchronous operation will have
-unfinished work, as if by maintaining the existence of one or more objects of
-class `io_service::work` constructed using the `io_service`, until immediately
-after the handler for the asynchronous operation has been invoked.
-
-When an asynchronous operation is complete, the handler for the operation will
-be invoked as if by:
-
-# Constructing a bound completion handler `bch` for the handler, as described
-  below.
-
-# Calling `ios.post(bch)` to schedule the handler for deferred invocation,
-  where `ios` is the associated `io_service`.
-
-This implies that the handler must not be called directly from within
-the initiating function, even if the asynchronous operation completes
-immediately.
-
-A bound completion handler is a handler object that contains a copy of a
-user-supplied handler, where the user-supplied handler accepts one or more
-arguments. The bound completion handler does not accept any arguments, and
-contains values to be passed as arguments to the user-supplied handler. The
-bound completion handler forwards the `asio_handler_allocate()`,
-`asio_handler_deallocate()`, and `asio_handler_invoke()` calls to the
-corresponding functions for the user-supplied handler. A bound completion
-handler meets the requirements for a [link
-boost_asio.reference.CompletionHandler completion handler].
-
-For example, a bound completion handler for a `ReadHandler` may be implemented
-as follows:
-
-  template<class ReadHandler>
-  struct bound_read_handler
-  {
-    bound_read_handler(ReadHandler handler, const error_code& ec, size_t s)
-      : handler_(handler), ec_(ec), s_(s)
-    {
-    }
-
-    void operator()()
-    {
-      handler_(ec_, s_);
-    }
-
-    ReadHandler handler_;
-    const error_code ec_;
-    const size_t s_;
-  };
-
-  template<class ReadHandler>
-  void* asio_handler_allocate(size_t size,
-                              bound_read_handler<ReadHandler>* this_handler)
-  {
-    using boost::asio::asio_handler_allocate;
-    return asio_handler_allocate(size, &this_handler->handler_);
-  }
+[section General asynchronous operation concepts]
+
+An ['initiating function] is a function which may be called to start an
+asynchronous operation. A ['completion handler] is a function object that will
+be invoked, at most once, with the result of the asynchronous operation.
+
+The lifecycle of an asynchronous operation is comprised of the following events
+and phases:
+
+[mdash] Event 1: The asynchronous operation is started by a call to the
+initiating function.
+
+[mdash] Phase 1: The asynchronous operation is now ['outstanding].
+
+[mdash] Event 2: The externally observable side effects of the asynchronous
+operation, if any, are fully established. The completion handler is submitted
+to an executor.
+
+[mdash] Phase 2: The asynchronous operation is now ['completed].
+
+[mdash] Event 3: The completion handler is called with the result of the
+asynchronous operation.
+
+In this library, all functions with the prefix `async_` are initiating
+functions.
+
+[endsect]
+
+[section:completion_token Completion tokens and handlers]
+
+Initiating functions:
+
+[mdash] are function templates with template parameter `CompletionToken`;
+
+[mdash] accept, as the final parameter, a ['completion token] object `token`
+of type `CompletionToken`;
+
+[mdash] specify a ['completion signature], which is a call signature (C++Std
+[func.def]) `Signature` that determines the arguments to the completion
+handler.
+
+An initiating function determines the type `CompletionHandler` of its
+completion handler function object by performing `typename
+async_result<decay_t<CompletionToken>, Signature>::completion_handler_type`.
+The completion handler object `completion_handler` is initialized with
+`forward<CompletionToken>(token)`. [inline_note No other requirements are
+placed on the type `CompletionToken`.]
 
-  template<class ReadHandler>
-  void asio_handler_deallocate(void* pointer, std::size_t size,
-                               bound_read_handler<ReadHandler>* this_handler)
+The type `CompletionHandler` must satisfy the requirements of `Destructible`
+(C++Std [destructible]) and `MoveConstructible` (C++Std
+[moveconstructible]), and be callable with the specified call signature.
+
+In this library, all initiating functions specify a ['Completion signature]
+element that defines the call signature `Signature`. The ['Completion
+signature] elements in this Technical Specification have named parameters, and
+the results of an asynchronous operation are specified in terms of these names.
+
+[endsect]
+
+[section Automatic deduction of initiating function return type]
+
+The return type of an initiating function is `typename
+async_result<decay_t<CompletionToken>, Signature>::return_type`.
+
+For the sake of exposition, this library sometimes annotates functions with a
+return type ['[^DEDUCED]]. For every function declaration that returns
+['[^DEDUCED]], the meaning is equivalent to specifying the return type as
+`typename async_result<decay_t<CompletionToken>, Signature>::return_type`.
+
+[endsect]
+
+[section Production of initiating function return value]
+
+An initiating function produces its return type as follows:
+
+[mdash] constructing an object `result` of type
+`async_result<decay_t<CompletionToken>, Signature>`, initialized as
+`result(completion_handler)`; and
+
+[mdash] using `result.get()` as the operand of the return statement.
+
+\[['Example:] Given an asynchronous operation with ['Completion signature]
+`void(R1 r1, R2 r2)`, an initiating function meeting these requirements may be
+implemented as follows:
+
+  template<class CompletionToken>
+  auto async_xyz(T1 t1, T2 t2, CompletionToken&& token)
   {
-    using boost::asio::asio_handler_deallocate;
-    asio_handler_deallocate(pointer, size, &this_handler->handler_);
+    typename async_result<decay_t<CompletionToken>, void(R1, R2)>::completion_handler_type
+      completion_handler(forward<CompletionToken>(token));
+
+    async_result<decay_t<CompletionToken>, void(R1, R2)> result(completion_handler);
+
+    // initiate the operation and cause completion_handler to be invoked with
+    // the result
+
+    return result.get();
   }
 
-  template<class F, class ReadHandler>
-  void asio_handler_invoke(const F& f,
-                           bound_read_handler<ReadHandler>* this_handler)
+For convenience, initiating functions may be implemented using the
+`async_completion` template:
+
+  template<class CompletionToken>
+  auto async_xyz(T1 t1, T2 t2, CompletionToken&& token)
   {
-    using boost::asio::asio_handler_invoke;
-    asio_handler_invoke(f, &this_handler->handler_);
+    async_completion<CompletionToken, void(R1, R2)> init(token);
+
+    // initiate the operation and cause init.completion_handler to be invoked
+    // with the result
+
+    return init.result.get();
   }
 
-If the thread that initiates an asynchronous operation terminates before the
-associated handler is invoked, the behaviour is implementation-defined.
-Specifically, on __Windows__ versions prior to Vista, unfinished operations are
-cancelled when the initiating thread exits.
-
-The handler argument to an initiating function defines a handler identity. That
-is, the original handler argument and any copies of the handler argument will
-be considered equivalent. If the implementation needs to allocate storage for
-an asynchronous operation, the implementation will perform
-`asio_handler_allocate(size, &h)`, where `size` is the required size in bytes,
-and `h` is the handler. The implementation will perform
-`asio_handler_deallocate(p, size, &h)`, where `p` is a pointer to the storage,
-to deallocate the storage prior to the invocation of the handler via
-`asio_handler_invoke`. Multiple storage blocks may be allocated for a single
-asynchronous operation.
+'''&mdash;'''['end example]\]
 
-[heading Return type of an initiating function]
+[endsect]
+
+[section Lifetime of initiating function arguments]
+
+Unless otherwise specified, the lifetime of arguments to initiating functions
+shall be treated as follows:
+
+[mdash] If the parameter has a pointer type or has a type of lvalue reference
+to non-const, the implementation may assume the validity of the pointee or
+referent, respectively, until the completion handler is invoked. [inline_note
+In other words, the program must guarantee the validity of the argument until
+the completion handler is invoked.]
+
+[mdash] Otherwise, the implementation must not assume the validity of the
+argument after the initiating function completes. [inline_note In other words,
+the program is not required to guarantee the validity of the argument after the
+initiating function completes.] The implementation may make copies of the
+argument, and all copies shall be destroyed no later than immediately after
+invocation of the completion handler.
+
+[endsect]
+
+[section Non-blocking requirements on initiating functions]
+
+An initiating function shall not block (C++Std [defns.block]) the calling
+thread pending completion of the outstanding operation.
+
+[std_note Initiating functions may still block the calling thread for other
+reasons. For example, an initiating function may lock a mutex in order to
+synchronize access to shared data.]
+
+[endsect]
+
+[section Associated executor]
+
+Certain objects that participate in asynchronous operations have an
+['associated executor]. These are obtained as specified below.
+
+[endsect]
+
+[section I/O executor]
+
+An asynchronous operation has an associated executor satisfying the [link
+boost_asio.reference.Executor1 `Executor`] requirements. If not otherwise specified by
+the asynchronous operation, this associated executor is an object of type
+`system_executor`.
+
+All asynchronous operations in this library have an associated executor object
+that is determined as follows:
+
+[mdash] If the initiating function is a member function, the associated
+executor is that returned by the `get_executor` member function on the same
+object.
 
-By default, initiating functions return `void`. This is always the case when
-the handler is a function pointer, C++11 lambda, or a function object produced
-by `boost::bind` or `std::bind`.
+[mdash] If the initiating function is not a member function, the associated
+executor is that returned by the `get_executor` member function of the first
+argument to the initiating function.
 
-For other types, the return type may be customised via a two-step process:
+Let `Executor1` be the type of the associated executor. Let `ex1` be a value of
+type `Executor1`, representing the associated executor object obtained as
+described above.
 
-# A specialisation of the [link boost_asio.reference.handler_type `handler_type`]
-template, which is used to determine the true handler type based on the
-asynchronous operation's handler's signature.
+[endsect]
+
+[section Completion handler executor]
+
+A completion handler object of type `CompletionHandler` has an associated
+executor of type `Executor2` satisfying the [link boost_asio.reference.Executor1
+Executor requirements]. The type `Executor2` is
+`associated_executor_t<CompletionHandler, Executor1>`. Let `ex2` be a value of
+type `Executor2` obtained by performing
+`get_associated_executor(completion_handler, ex1)`.
 
-# A specialisation of the [link boost_asio.reference.async_result `async_result`]
-template, which is used both to determine the return type and to extract the
-return value from the handler.
+[endsect]
+
+[section Outstanding work]
 
-These two templates have been specialised to provide support for [link
-boost_asio.overview.core.spawn stackful coroutines] and the C++11 `std::future`
-class.
+Until the asynchronous operation has completed, the asynchronous operation
+shall maintain:
 
-As an example, consider what happens when enabling `std::future` support by
-using the `boost::asio::use_future` special value, as in:
+[mdash] an object `work1` of type `executor_work_guard<Executor1>`, initialized
+as `work1(ex1)`, and where `work1.owns_work() == true`; and
 
-  std::future<std::size_t> length =
-    my_socket.async_read_some(my_buffer, boost::asio::use_future);
+[mdash] an object `work2` of type `executor_work_guard<Executor2>`, initialized
+as `work2(ex2)`, and where `work2.owns_work() == true`.
 
-When a handler signature has the form:
+[endsect]
 
-  void handler(error_code ec, result_type result);
+[section Allocation of intermediate storage]
 
-the initiating function returns a `std::future` templated on `result_type`. In
-the above `async_read_some` example, this is `std::size_t`. If the asynchronous
-operation fails, the `error_code` is converted into a `system_error` exception
-and passed back to the caller through the future.
+Asynchronous operations may allocate memory. [inline_note Such as a data
+structure to store copies of the `completion_handler` object and the initiating
+function's arguments.]
 
-Where a handler signature has the form:
+Let `Alloc1` be a type, satisfying the [link boost_asio.reference.ProtoAllocator
+`ProtoAllocator`] requirements, that represents the asynchronous operation's
+default allocation strategy. [inline_note Typically `std::allocator<void>`.]
+Let `alloc1` be a value of type `Alloc1`.
 
-  void handler(error_code ec);
+A completion handler object of type `CompletionHandler` has an associated
+allocator object `alloc2` of type `Alloc2` satisfying the [link
+boost_asio.reference.ProtoAllocator `ProtoAllocator`] requirements. The type `Alloc2`
+is `associated_allocator_t<CompletionHandler, Alloc1>`. Let `alloc2` be a value
+of type `Alloc2` obtained by performing
+`get_associated_allocator(completion_handler, alloc1)`.
 
-the initiating function instead returns `std::future<void>`.
+The asynchronous operations defined in this library:
+
+[mdash] If required, allocate memory using only the completion handler's
+associated allocator.
+
+[mdash] Prior to completion handler execution, deallocate any memory allocated
+using the completion handler's associated allocator.
+
+[std_note The implementation may perform operating system or underlying API
+calls that perform memory allocations not using the associated allocator.
+Invocations of the allocator functions may not introduce data races (See C++Std
+\[res.on.data.races\]).]
+
+[endsect]
+
+[section Execution of completion handler on completion of asynchronous operation]
+
+Let `Args...` be the argument types of the completion signature `Signature` and
+let [^['N]] be `sizeof...(Args)`. Let [^['i]] be in the range [half_open_range
+`0`,[^['N]]]. Let [^T[sub ['i]]] be the [^['i]]th type in `Args...` and let
+[^t[sub ['i]]] be the [^['i]]th completion handler argument associated with
+[^T[sub ['i]]].
+
+Let `f` be a function object, callable as `f()`, that invokes
+`completion_handler` as if by [^completion_handler(forward<T[sub ['0]]>(t[sub
+['0]]), ..., forward<T[sub ['N-1]]>(t[sub ['N-1]]))].
+
+If an asynchonous operation completes immediately (that is, within the thread
+of execution calling the initiating function, and before the initiating
+function returns), the completion handler shall be submitted for execution as
+if by performing `ex2.post(std::move(f), alloc2)`. Otherwise, the completion
+handler shall be submitted for execution as if by performing
+`ex2.dispatch(std::move(f), alloc2)`.
+
+[endsect]
+
+[section Completion handlers and exceptions]
+
+Completion handlers are permitted to throw exceptions. The effect of any
+exception propagated from the execution of a completion handler is determined
+by the executor which is executing the completion handler.
+
+[endsect]
 
 [endsect]
diff --git a/doc/requirements/asynchronous_socket_operations.qbk b/doc/requirements/asynchronous_socket_operations.qbk
new file mode 100644
index 0000000000..a1963e4b73
--- /dev/null
+++ b/doc/requirements/asynchronous_socket_operations.qbk
@@ -0,0 +1,39 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:asynchronous_socket_operations Requirements on asynchronous socket operations]
+
+In this library, ['asynchronous socket operations] are those member functions
+having prefix `async_`.
+
+For an object `s`, a program may initiate asynchronous socket operations such
+that there are multiple simultaneously outstanding asynchronous operations.
+
+When there are multiple outstanding asynchronous [link
+boost_asio.reference.read_write_operations read operations] on `s`:
+
+[mdash] having no argument `flags` of type `socket_base::message_flags`, or
+
+[mdash] having an argument `flags` of type `socket_base::message_flags` but
+where `(flags & socket_base::message_out_of_band) == 0`
+
+then the `buffers` are filled in the order in which these operations were
+issued. The order of invocation of the completion handlers for these operations
+is unspecified.
+
+When there are multiple outstanding asynchronous [link
+boost_asio.reference.read_write_operations read operations] on `s` having an argument
+`flags` of type `socket_base::message_flags` where `(flags &
+socket_base::message_out_of_band) != 0` then the `buffers` are filled in the
+order in which these operations were issued.
+
+When there are multiple outstanding asynchronous [link
+boost_asio.reference.read_write_operations write operations] on `s`, the `buffers`
+are transmitted in the order in which these operations were issued. The order
+of invocation of the completion handlers for these operations is unspecified.
+
+[endsect]
diff --git a/doc/requirements/read_write_operations.qbk b/doc/requirements/read_write_operations.qbk
new file mode 100644
index 0000000000..250136c56d
--- /dev/null
+++ b/doc/requirements/read_write_operations.qbk
@@ -0,0 +1,34 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:read_write_operations Requirements on read and write operations]
+
+A ['read operation] is an operation that reads data into a mutable buffer
+sequence argument of a type meeting [link boost_asio.reference.MutableBufferSequence
+`MutableBufferSequence`] requirements. The mutable buffer sequence specifies
+memory where the data should be placed. A read operation shall always fill a
+buffer in the sequence completely before proceeding to the next.
+
+A ['write operation] is an operation that writes data from a constant buffer
+sequence argument of a type meeting [link boost_asio.reference.ConstBufferSequence
+`ConstBufferSequence`] requirements. The constant buffer sequence specifies
+memory where the data to be written is located. A write operation shall always
+write a buffer in the sequence completely before proceeding to the next.
+
+If a read or write operation is also an [link
+boost_asio.reference.asynchronous_operations asynchronous operation], the operation
+shall maintain one or more copies of the buffer sequence until such time as the
+operation no longer requires access to the memory specified by the buffers in
+the sequence. The program shall ensure the memory remains valid until:
+
+[mdash] the last copy of the buffer sequence is destroyed, or
+
+[mdash] the completion handler for the asynchronous operation is invoked,
+
+whichever comes first.
+
+[endsect]
diff --git a/doc/requirements/synchronous_socket_operations.qbk b/doc/requirements/synchronous_socket_operations.qbk
new file mode 100644
index 0000000000..ac2ca6b444
--- /dev/null
+++ b/doc/requirements/synchronous_socket_operations.qbk
@@ -0,0 +1,37 @@
+[/
+ / Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+ /
+ / Distributed under the Boost Software License, Version 1.0. (See accompanying
+ / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ /]
+
+[section:synchronous_socket_operations Requirements on synchronous socket operations]
+
+In this section, ['synchronous socket operations] are those member functions
+specified as two overloads, with and without an argument of type `error_code&`:
+
+  ``[*['R f]]``(``['[*A1]]`` a1, ``['[*A2]]`` a2, ..., ``['[*AN]]`` aN);
+  ``[*['R f]]``(``['[*A1]]`` a1, ``['[*A2]]`` a2, ..., ``['[*AN]]`` aN, error_code& ec);
+
+For an object `s`, the conditions under which its synchronous socket operations
+may block the calling thread (C++Std [defns.block]) are determined as follows.
+
+If:
+
+[mdash] `s.non_blocking() == true`,
+
+[mdash] the synchronous socket operation is specified in terms of a __POSIX__
+function other than `__poll__`,
+
+[mdash] that __POSIX__ function lists `EWOULDBLOCK` or `EAGAIN`
+in its failure conditions, and
+
+[mdash] the effects of the operation cannot be established immediately
+
+then the synchronous socket operation shall not block the calling thread.
+[inline_note And the effects of the operation are not established.]
+
+Otherwise, the synchronous socket operation shall block the calling thread
+until the effects are established.
+
+[endsect]
diff --git a/example/cpp03/allocation/server.cpp b/example/cpp03/allocation/server.cpp
index 40bd91736f..15454df702 100644
--- a/example/cpp03/allocation/server.cpp
+++ b/example/cpp03/allocation/server.cpp
@@ -120,8 +120,8 @@ class session
   : public boost::enable_shared_from_this<session>
 {
 public:
-  session(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -183,11 +183,11 @@ typedef boost::shared_ptr<session> session_ptr;
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : io_service_(io_service),
-      acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
+  server(boost::asio::io_context& io_context, short port)
+    : io_context_(io_context),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
   {
-    session_ptr new_session(new session(io_service_));
+    session_ptr new_session(new session(io_context_));
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
@@ -201,14 +201,14 @@ class server
       new_session->start();
     }
 
-    new_session.reset(new session(io_service_));
+    new_session.reset(new session(io_context_));
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   tcp::acceptor acceptor_;
 };
 
@@ -222,12 +222,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/buffers/reference_counted.cpp b/example/cpp03/buffers/reference_counted.cpp
index 504662cd2b..81128f5986 100644
--- a/example/cpp03/buffers/reference_counted.cpp
+++ b/example/cpp03/buffers/reference_counted.cpp
@@ -43,8 +43,8 @@ class session
   : public boost::enable_shared_from_this<session>
 {
 public:
-  session(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -76,11 +76,11 @@ typedef boost::shared_ptr<session> session_ptr;
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : io_service_(io_service),
-      acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
+  server(boost::asio::io_context& io_context, short port)
+    : io_context_(io_context),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
   {
-    session_ptr new_session(new session(io_service_));
+    session_ptr new_session(new session(io_context_));
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
@@ -94,14 +94,14 @@ class server
       new_session->start();
     }
 
-    new_session.reset(new session(io_service_));
+    new_session.reset(new session(io_context_));
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   tcp::acceptor acceptor_;
 };
 
@@ -115,12 +115,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/chat/chat_client.cpp b/example/cpp03/chat/chat_client.cpp
index 71bd50d6d2..e37dfe4b57 100644
--- a/example/cpp03/chat/chat_client.cpp
+++ b/example/cpp03/chat/chat_client.cpp
@@ -23,24 +23,26 @@ typedef std::deque<chat_message> chat_message_queue;
 class chat_client
 {
 public:
-  chat_client(boost::asio::io_service& io_service,
-      tcp::resolver::iterator endpoint_iterator)
-    : io_service_(io_service),
-      socket_(io_service)
+  chat_client(boost::asio::io_context& io_context,
+      const tcp::resolver::results_type& endpoints)
+    : io_context_(io_context),
+      socket_(io_context)
   {
-    boost::asio::async_connect(socket_, endpoint_iterator,
+    boost::asio::async_connect(socket_, endpoints,
         boost::bind(&chat_client::handle_connect, this,
           boost::asio::placeholders::error));
   }
 
   void write(const chat_message& msg)
   {
-    io_service_.post(boost::bind(&chat_client::do_write, this, msg));
+    boost::asio::post(io_context_,
+        boost::bind(&chat_client::do_write, this, msg));
   }
 
   void close()
   {
-    io_service_.post(boost::bind(&chat_client::do_close, this));
+    boost::asio::post(io_context_,
+        boost::bind(&chat_client::do_close, this));
   }
 
 private:
@@ -128,7 +130,7 @@ class chat_client
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   tcp::socket socket_;
   chat_message read_msg_;
   chat_message_queue write_msgs_;
@@ -144,15 +146,14 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tcp::resolver resolver(io_service);
-    tcp::resolver::query query(argv[1], argv[2]);
-    tcp::resolver::iterator iterator = resolver.resolve(query);
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints = resolver.resolve(argv[1], argv[2]);
 
-    chat_client c(io_service, iterator);
+    chat_client c(io_context, endpoints);
 
-    boost::thread t(boost::bind(&boost::asio::io_service::run, &io_service));
+    boost::thread t(boost::bind(&boost::asio::io_context::run, &io_context));
 
     char line[chat_message::max_body_length + 1];
     while (std::cin.getline(line, chat_message::max_body_length + 1))
diff --git a/example/cpp03/chat/chat_server.cpp b/example/cpp03/chat/chat_server.cpp
index 611db89243..903b568bce 100644
--- a/example/cpp03/chat/chat_server.cpp
+++ b/example/cpp03/chat/chat_server.cpp
@@ -77,8 +77,8 @@ class chat_session
     public boost::enable_shared_from_this<chat_session>
 {
 public:
-  chat_session(boost::asio::io_service& io_service, chat_room& room)
-    : socket_(io_service),
+  chat_session(boost::asio::io_context& io_context, chat_room& room)
+    : socket_(io_context),
       room_(room)
   {
   }
@@ -177,17 +177,17 @@ typedef boost::shared_ptr<chat_session> chat_session_ptr;
 class chat_server
 {
 public:
-  chat_server(boost::asio::io_service& io_service,
+  chat_server(boost::asio::io_context& io_context,
       const tcp::endpoint& endpoint)
-    : io_service_(io_service),
-      acceptor_(io_service, endpoint)
+    : io_context_(io_context),
+      acceptor_(io_context, endpoint)
   {
     start_accept();
   }
 
   void start_accept()
   {
-    chat_session_ptr new_session(new chat_session(io_service_, room_));
+    chat_session_ptr new_session(new chat_session(io_context_, room_));
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&chat_server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
@@ -205,7 +205,7 @@ class chat_server
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   tcp::acceptor acceptor_;
   chat_room room_;
 };
@@ -225,18 +225,18 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     chat_server_list servers;
     for (int i = 1; i < argc; ++i)
     {
       using namespace std; // For atoi.
       tcp::endpoint endpoint(tcp::v4(), atoi(argv[i]));
-      chat_server_ptr server(new chat_server(io_service, endpoint));
+      chat_server_ptr server(new chat_server(io_context, endpoint));
       servers.push_back(server);
     }
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/chat/posix_chat_client.cpp b/example/cpp03/chat/posix_chat_client.cpp
index 434f9f5916..40844c94e4 100644
--- a/example/cpp03/chat/posix_chat_client.cpp
+++ b/example/cpp03/chat/posix_chat_client.cpp
@@ -24,14 +24,14 @@ namespace posix = boost::asio::posix;
 class posix_chat_client
 {
 public:
-  posix_chat_client(boost::asio::io_service& io_service,
-      tcp::resolver::iterator endpoint_iterator)
-    : socket_(io_service),
-      input_(io_service, ::dup(STDIN_FILENO)),
-      output_(io_service, ::dup(STDOUT_FILENO)),
+  posix_chat_client(boost::asio::io_context& io_context,
+      const tcp::resolver::results_type& endpoints)
+    : socket_(io_context),
+      input_(io_context, ::dup(STDIN_FILENO)),
+      output_(io_context, ::dup(STDOUT_FILENO)),
       input_buffer_(chat_message::max_body_length)
   {
-    boost::asio::async_connect(socket_, endpoint_iterator,
+    boost::asio::async_connect(socket_, endpoints,
         boost::bind(&posix_chat_client::handle_connect, this,
           boost::asio::placeholders::error));
   }
@@ -182,15 +182,14 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tcp::resolver resolver(io_service);
-    tcp::resolver::query query(argv[1], argv[2]);
-    tcp::resolver::iterator iterator = resolver.resolve(query);
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints = resolver.resolve(argv[1], argv[2]);
 
-    posix_chat_client c(io_service, iterator);
+    posix_chat_client c(io_context, endpoints);
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/echo/async_tcp_echo_server.cpp b/example/cpp03/echo/async_tcp_echo_server.cpp
index 2aa2e6c65e..f0a672dde6 100644
--- a/example/cpp03/echo/async_tcp_echo_server.cpp
+++ b/example/cpp03/echo/async_tcp_echo_server.cpp
@@ -18,8 +18,8 @@ using boost::asio::ip::tcp;
 class session
 {
 public:
-  session(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -76,9 +76,9 @@ class session
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : io_service_(io_service),
-      acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
+  server(boost::asio::io_context& io_context, short port)
+    : io_context_(io_context),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
   {
     start_accept();
   }
@@ -86,7 +86,7 @@ class server
 private:
   void start_accept()
   {
-    session* new_session = new session(io_service_);
+    session* new_session = new session(io_context_);
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
@@ -107,7 +107,7 @@ class server
     start_accept();
   }
 
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   tcp::acceptor acceptor_;
 };
 
@@ -121,12 +121,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/echo/async_udp_echo_server.cpp b/example/cpp03/echo/async_udp_echo_server.cpp
index 97049c9dd8..bdcd4f785b 100644
--- a/example/cpp03/echo/async_udp_echo_server.cpp
+++ b/example/cpp03/echo/async_udp_echo_server.cpp
@@ -18,8 +18,8 @@ using boost::asio::ip::udp;
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : socket_(io_service, udp::endpoint(udp::v4(), port))
+  server(boost::asio::io_context& io_context, short port)
+    : socket_(io_context, udp::endpoint(udp::v4(), port))
   {
     socket_.async_receive_from(
         boost::asio::buffer(data_, max_length), sender_endpoint_,
@@ -76,12 +76,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/echo/blocking_tcp_echo_client.cpp b/example/cpp03/echo/blocking_tcp_echo_client.cpp
index 77792af005..1def9d0bc0 100644
--- a/example/cpp03/echo/blocking_tcp_echo_client.cpp
+++ b/example/cpp03/echo/blocking_tcp_echo_client.cpp
@@ -27,14 +27,14 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tcp::resolver resolver(io_service);
-    tcp::resolver::query query(tcp::v4(), argv[1], argv[2]);
-    tcp::resolver::iterator iterator = resolver.resolve(query);
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints =
+      resolver.resolve(tcp::v4(), argv[1], argv[2]);
 
-    tcp::socket s(io_service);
-    boost::asio::connect(s, iterator);
+    tcp::socket s(io_context);
+    boost::asio::connect(s, endpoints);
 
     using namespace std; // For strlen.
     std::cout << "Enter message: ";
diff --git a/example/cpp03/echo/blocking_tcp_echo_server.cpp b/example/cpp03/echo/blocking_tcp_echo_server.cpp
index 0c4529b4cc..c4acbe4e15 100644
--- a/example/cpp03/echo/blocking_tcp_echo_server.cpp
+++ b/example/cpp03/echo/blocking_tcp_echo_server.cpp
@@ -45,12 +45,12 @@ void session(socket_ptr sock)
   }
 }
 
-void server(boost::asio::io_service& io_service, unsigned short port)
+void server(boost::asio::io_context& io_context, unsigned short port)
 {
-  tcp::acceptor a(io_service, tcp::endpoint(tcp::v4(), port));
+  tcp::acceptor a(io_context, tcp::endpoint(tcp::v4(), port));
   for (;;)
   {
-    socket_ptr sock(new tcp::socket(io_service));
+    socket_ptr sock(new tcp::socket(io_context));
     a.accept(*sock);
     boost::thread t(boost::bind(session, sock));
   }
@@ -66,10 +66,10 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server(io_service, atoi(argv[1]));
+    server(io_context, atoi(argv[1]));
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/echo/blocking_udp_echo_client.cpp b/example/cpp03/echo/blocking_udp_echo_client.cpp
index 4f29e69b5e..3b1067a03e 100644
--- a/example/cpp03/echo/blocking_udp_echo_client.cpp
+++ b/example/cpp03/echo/blocking_udp_echo_client.cpp
@@ -27,20 +27,20 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    udp::socket s(io_service, udp::endpoint(udp::v4(), 0));
+    udp::socket s(io_context, udp::endpoint(udp::v4(), 0));
 
-    udp::resolver resolver(io_service);
-    udp::resolver::query query(udp::v4(), argv[1], argv[2]);
-    udp::resolver::iterator iterator = resolver.resolve(query);
+    udp::resolver resolver(io_context);
+    udp::resolver::results_type endpoints =
+      resolver.resolve(udp::v4(), argv[1], argv[2]);
 
     using namespace std; // For strlen.
     std::cout << "Enter message: ";
     char request[max_length];
     std::cin.getline(request, max_length);
     size_t request_length = strlen(request);
-    s.send_to(boost::asio::buffer(request, request_length), *iterator);
+    s.send_to(boost::asio::buffer(request, request_length), *endpoints.begin());
 
     char reply[max_length];
     udp::endpoint sender_endpoint;
diff --git a/example/cpp03/echo/blocking_udp_echo_server.cpp b/example/cpp03/echo/blocking_udp_echo_server.cpp
index 31c9cd8b22..5e70a6e44f 100644
--- a/example/cpp03/echo/blocking_udp_echo_server.cpp
+++ b/example/cpp03/echo/blocking_udp_echo_server.cpp
@@ -16,9 +16,9 @@ using boost::asio::ip::udp;
 
 enum { max_length = 1024 };
 
-void server(boost::asio::io_service& io_service, unsigned short port)
+void server(boost::asio::io_context& io_context, unsigned short port)
 {
-  udp::socket sock(io_service, udp::endpoint(udp::v4(), port));
+  udp::socket sock(io_context, udp::endpoint(udp::v4(), port));
   for (;;)
   {
     char data[max_length];
@@ -39,10 +39,10 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server(io_service, atoi(argv[1]));
+    server(io_context, atoi(argv[1]));
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/fork/daemon.cpp b/example/cpp03/fork/daemon.cpp
index f16f7cf8c9..494e8d1bfa 100644
--- a/example/cpp03/fork/daemon.cpp
+++ b/example/cpp03/fork/daemon.cpp
@@ -8,7 +8,7 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include <boost/asio/signal_set.hpp>
 #include <boost/array.hpp>
@@ -23,8 +23,8 @@ using boost::asio::ip::udp;
 class udp_daytime_server
 {
 public:
-  udp_daytime_server(boost::asio::io_service& io_service)
-    : socket_(io_service, udp::endpoint(udp::v4(), 13))
+  udp_daytime_server(boost::asio::io_context& io_context)
+    : socket_(io_context, udp::endpoint(udp::v4(), 13))
   {
     start_receive();
   }
@@ -62,24 +62,24 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     // Initialise the server before becoming a daemon. If the process is
     // started from a shell, this means any errors will be reported back to the
     // user.
-    udp_daytime_server server(io_service);
+    udp_daytime_server server(io_context);
 
     // Register signal handlers so that the daemon may be shut down. You may
     // also want to register for other signals, such as SIGHUP to trigger a
     // re-read of a configuration file.
-    boost::asio::signal_set signals(io_service, SIGINT, SIGTERM);
+    boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
     signals.async_wait(
-        boost::bind(&boost::asio::io_service::stop, &io_service));
+        boost::bind(&boost::asio::io_context::stop, &io_context));
 
-    // Inform the io_service that we are about to become a daemon. The
-    // io_service cleans up any internal resources, such as threads, that may
+    // Inform the io_context that we are about to become a daemon. The
+    // io_context cleans up any internal resources, such as threads, that may
     // interfere with forking.
-    io_service.notify_fork(boost::asio::io_service::fork_prepare);
+    io_context.notify_fork(boost::asio::io_context::fork_prepare);
 
     // Fork the process and have the parent exit. If the process was started
     // from a shell, this returns control to the user. Forking a new process is
@@ -92,15 +92,15 @@ int main()
         //
         // When the exit() function is used, the program terminates without
         // invoking local variables' destructors. Only global variables are
-        // destroyed. As the io_service object is a local variable, this means
+        // destroyed. As the io_context object is a local variable, this means
         // we do not have to call:
         //
-        //   io_service.notify_fork(boost::asio::io_service::fork_parent);
+        //   io_context.notify_fork(boost::asio::io_context::fork_parent);
         //
         // However, this line should be added before each call to exit() if
-        // using a global io_service object. An additional call:
+        // using a global io_context object. An additional call:
         //
-        //   io_service.notify_fork(boost::asio::io_service::fork_prepare);
+        //   io_context.notify_fork(boost::asio::io_context::fork_prepare);
         //
         // should also precede the second fork().
         exit(0);
@@ -171,14 +171,14 @@ int main()
       return 1;
     }
 
-    // Inform the io_service that we have finished becoming a daemon. The
-    // io_service uses this opportunity to create any internal file descriptors
+    // Inform the io_context that we have finished becoming a daemon. The
+    // io_context uses this opportunity to create any internal file descriptors
     // that need to be private to the new process.
-    io_service.notify_fork(boost::asio::io_service::fork_child);
+    io_context.notify_fork(boost::asio::io_context::fork_child);
 
-    // The io_service can now be used normally.
+    // The io_context can now be used normally.
     syslog(LOG_INFO | LOG_USER, "Daemon started");
-    io_service.run();
+    io_context.run();
     syslog(LOG_INFO | LOG_USER, "Daemon stopped");
   }
   catch (std::exception& e)
diff --git a/example/cpp03/fork/process_per_connection.cpp b/example/cpp03/fork/process_per_connection.cpp
index 70faa02d57..305cdc2d23 100644
--- a/example/cpp03/fork/process_per_connection.cpp
+++ b/example/cpp03/fork/process_per_connection.cpp
@@ -8,7 +8,7 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/signal_set.hpp>
 #include <boost/asio/write.hpp>
@@ -25,11 +25,11 @@ using boost::asio::ip::tcp;
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, unsigned short port)
-    : io_service_(io_service),
-      signal_(io_service, SIGCHLD),
-      acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
-      socket_(io_service)
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : io_context_(io_context),
+      signal_(io_context, SIGCHLD),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port)),
+      socket_(io_context)
   {
     start_signal_wait();
     start_accept();
@@ -65,17 +65,17 @@ class server
   {
     if (!ec)
     {
-      // Inform the io_service that we are about to fork. The io_service cleans
+      // Inform the io_context that we are about to fork. The io_context cleans
       // up any internal resources, such as threads, that may interfere with
       // forking.
-      io_service_.notify_fork(boost::asio::io_service::fork_prepare);
+      io_context_.notify_fork(boost::asio::io_context::fork_prepare);
 
       if (fork() == 0)
       {
-        // Inform the io_service that the fork is finished and that this is the
-        // child process. The io_service uses this opportunity to create any
+        // Inform the io_context that the fork is finished and that this is the
+        // child process. The io_context uses this opportunity to create any
         // internal file descriptors that must be private to the new process.
-        io_service_.notify_fork(boost::asio::io_service::fork_child);
+        io_context_.notify_fork(boost::asio::io_context::fork_child);
 
         // The child won't be accepting new connections, so we can close the
         // acceptor. It remains open in the parent.
@@ -88,11 +88,11 @@ class server
       }
       else
       {
-        // Inform the io_service that the fork is finished (or failed) and that
-        // this is the parent process. The io_service uses this opportunity to
+        // Inform the io_context that the fork is finished (or failed) and that
+        // this is the parent process. The io_context uses this opportunity to
         // recreate any internal resources that were cleaned up during
         // preparation for the fork.
-        io_service_.notify_fork(boost::asio::io_service::fork_parent);
+        io_context_.notify_fork(boost::asio::io_context::fork_parent);
 
         socket_.close();
         start_accept();
@@ -129,7 +129,7 @@ class server
       start_read();
   }
 
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   boost::asio::signal_set signal_;
   tcp::acceptor acceptor_;
   tcp::socket socket_;
@@ -146,12 +146,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/http/client/async_client.cpp b/example/cpp03/http/client/async_client.cpp
index c240ad6642..61832aa34f 100644
--- a/example/cpp03/http/client/async_client.cpp
+++ b/example/cpp03/http/client/async_client.cpp
@@ -20,10 +20,10 @@ using boost::asio::ip::tcp;
 class client
 {
 public:
-  client(boost::asio::io_service& io_service,
+  client(boost::asio::io_context& io_context,
       const std::string& server, const std::string& path)
-    : resolver_(io_service),
-      socket_(io_service)
+    : resolver_(io_context),
+      socket_(io_context)
   {
     // Form the request. We specify the "Connection: close" header so that the
     // server will close the socket after transmitting the response. This will
@@ -36,22 +36,21 @@ class client
 
     // Start an asynchronous resolve to translate the server and service names
     // into a list of endpoints.
-    tcp::resolver::query query(server, "http");
-    resolver_.async_resolve(query,
+    resolver_.async_resolve(server, "http",
         boost::bind(&client::handle_resolve, this,
           boost::asio::placeholders::error,
-          boost::asio::placeholders::iterator));
+          boost::asio::placeholders::results));
   }
 
 private:
   void handle_resolve(const boost::system::error_code& err,
-      tcp::resolver::iterator endpoint_iterator)
+      const tcp::resolver::results_type& endpoints)
   {
     if (!err)
     {
       // Attempt a connection to each endpoint in the list until we
       // successfully establish a connection.
-      boost::asio::async_connect(socket_, endpoint_iterator,
+      boost::asio::async_connect(socket_, endpoints,
           boost::bind(&client::handle_connect, this,
             boost::asio::placeholders::error));
     }
@@ -192,9 +191,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
-    client c(io_service, argv[1], argv[2]);
-    io_service.run();
+    boost::asio::io_context io_context;
+    client c(io_context, argv[1], argv[2]);
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/http/client/sync_client.cpp b/example/cpp03/http/client/sync_client.cpp
index 2eea356ca5..6813e053f5 100644
--- a/example/cpp03/http/client/sync_client.cpp
+++ b/example/cpp03/http/client/sync_client.cpp
@@ -28,16 +28,15 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     // Get a list of endpoints corresponding to the server name.
-    tcp::resolver resolver(io_service);
-    tcp::resolver::query query(argv[1], "http");
-    tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints = resolver.resolve(argv[1], "http");
 
     // Try each endpoint until we successfully establish a connection.
-    tcp::socket socket(io_service);
-    boost::asio::connect(socket, endpoint_iterator);
+    tcp::socket socket(io_context);
+    boost::asio::connect(socket, endpoints);
 
     // Form the request. We specify the "Connection: close" header so that the
     // server will close the socket after transmitting the response. This will
diff --git a/example/cpp03/http/server/connection.cpp b/example/cpp03/http/server/connection.cpp
index a9b04f401c..c922257697 100644
--- a/example/cpp03/http/server/connection.cpp
+++ b/example/cpp03/http/server/connection.cpp
@@ -17,9 +17,9 @@
 namespace http {
 namespace server {
 
-connection::connection(boost::asio::io_service& io_service,
+connection::connection(boost::asio::io_context& io_context,
     connection_manager& manager, request_handler& handler)
-  : socket_(io_service),
+  : socket_(io_context),
     connection_manager_(manager),
     request_handler_(handler)
 {
diff --git a/example/cpp03/http/server/connection.hpp b/example/cpp03/http/server/connection.hpp
index e38b43a881..80bf20df5e 100644
--- a/example/cpp03/http/server/connection.hpp
+++ b/example/cpp03/http/server/connection.hpp
@@ -32,8 +32,8 @@ class connection
     private boost::noncopyable
 {
 public:
-  /// Construct a connection with the given io_service.
-  explicit connection(boost::asio::io_service& io_service,
+  /// Construct a connection with the given io_context.
+  explicit connection(boost::asio::io_context& io_context,
       connection_manager& manager, request_handler& handler);
 
   /// Get the socket associated with the connection.
diff --git a/example/cpp03/http/server/server.cpp b/example/cpp03/http/server/server.cpp
index 8ee0523a6d..1ebddad8d2 100644
--- a/example/cpp03/http/server/server.cpp
+++ b/example/cpp03/http/server/server.cpp
@@ -17,9 +17,9 @@ namespace server {
 
 server::server(const std::string& address, const std::string& port,
     const std::string& doc_root)
-  : io_service_(),
-    signals_(io_service_),
-    acceptor_(io_service_),
+  : io_context_(),
+    signals_(io_context_),
+    acceptor_(io_context_),
     connection_manager_(),
     new_connection_(),
     request_handler_(doc_root)
@@ -35,9 +35,9 @@ server::server(const std::string& address, const std::string& port,
   signals_.async_wait(boost::bind(&server::handle_stop, this));
 
   // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
-  boost::asio::ip::tcp::resolver resolver(io_service_);
-  boost::asio::ip::tcp::resolver::query query(address, port);
-  boost::asio::ip::tcp::endpoint endpoint = *resolver.resolve(query);
+  boost::asio::ip::tcp::resolver resolver(io_context_);
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
   acceptor_.open(endpoint.protocol());
   acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
   acceptor_.bind(endpoint);
@@ -48,16 +48,16 @@ server::server(const std::string& address, const std::string& port,
 
 void server::run()
 {
-  // The io_service::run() call will block until all asynchronous operations
+  // The io_context::run() call will block until all asynchronous operations
   // have finished. While the server is running, there is always at least one
   // asynchronous operation outstanding: the asynchronous accept call waiting
   // for new incoming connections.
-  io_service_.run();
+  io_context_.run();
 }
 
 void server::start_accept()
 {
-  new_connection_.reset(new connection(io_service_,
+  new_connection_.reset(new connection(io_context_,
         connection_manager_, request_handler_));
   acceptor_.async_accept(new_connection_->socket(),
       boost::bind(&server::handle_accept, this,
@@ -84,7 +84,7 @@ void server::handle_accept(const boost::system::error_code& e)
 void server::handle_stop()
 {
   // The server is stopped by cancelling all outstanding asynchronous
-  // operations. Once all operations have finished the io_service::run() call
+  // operations. Once all operations have finished the io_context::run() call
   // will exit.
   acceptor_.close();
   connection_manager_.stop_all();
diff --git a/example/cpp03/http/server/server.hpp b/example/cpp03/http/server/server.hpp
index 6662e3c2f4..8702dce85b 100644
--- a/example/cpp03/http/server/server.hpp
+++ b/example/cpp03/http/server/server.hpp
@@ -31,7 +31,7 @@ class server
   explicit server(const std::string& address, const std::string& port,
       const std::string& doc_root);
 
-  /// Run the server's io_service loop.
+  /// Run the server's io_context loop.
   void run();
 
 private:
@@ -44,8 +44,8 @@ class server
   /// Handle a request to stop the server.
   void handle_stop();
 
-  /// The io_service used to perform asynchronous operations.
-  boost::asio::io_service io_service_;
+  /// The io_context used to perform asynchronous operations.
+  boost::asio::io_context io_context_;
 
   /// The signal_set is used to register for process termination notifications.
   boost::asio::signal_set signals_;
diff --git a/example/cpp03/http/server2/Jamfile b/example/cpp03/http/server2/Jamfile
index ae62b82d0b..40487e02c1 100644
--- a/example/cpp03/http/server2/Jamfile
+++ b/example/cpp03/http/server2/Jamfile
@@ -24,7 +24,7 @@ exe http_server
   : <lib>@boost/libs/thread/build/boost_thread
     <lib>@boost/libs/system/build/boost_system
     connection.cpp
-    io_service_pool.cpp
+    io_context_pool.cpp
     main.cpp
     mime_types.cpp
     reply.cpp
diff --git a/example/cpp03/http/server2/Jamfile.v2 b/example/cpp03/http/server2/Jamfile.v2
index 41c1b05db9..2bad75f1c8 100644
--- a/example/cpp03/http/server2/Jamfile.v2
+++ b/example/cpp03/http/server2/Jamfile.v2
@@ -28,7 +28,7 @@ else if [ os.name ] = HAIKU
 
 exe server
   : connection.cpp
-    io_service_pool.cpp
+    io_context_pool.cpp
     main.cpp
     mime_types.cpp
     reply.cpp
diff --git a/example/cpp03/http/server2/connection.cpp b/example/cpp03/http/server2/connection.cpp
index e2700c6001..328e4a9fff 100644
--- a/example/cpp03/http/server2/connection.cpp
+++ b/example/cpp03/http/server2/connection.cpp
@@ -16,9 +16,9 @@
 namespace http {
 namespace server2 {
 
-connection::connection(boost::asio::io_service& io_service,
+connection::connection(boost::asio::io_context& io_context,
     request_handler& handler)
-  : socket_(io_service),
+  : socket_(io_context),
     request_handler_(handler)
 {
 }
diff --git a/example/cpp03/http/server2/connection.hpp b/example/cpp03/http/server2/connection.hpp
index 7dff608277..b9ba677f56 100644
--- a/example/cpp03/http/server2/connection.hpp
+++ b/example/cpp03/http/server2/connection.hpp
@@ -30,8 +30,8 @@ class connection
     private boost::noncopyable
 {
 public:
-  /// Construct a connection with the given io_service.
-  explicit connection(boost::asio::io_service& io_service,
+  /// Construct a connection with the given io_context.
+  explicit connection(boost::asio::io_context& io_context,
       request_handler& handler);
 
   /// Get the socket associated with the connection.
diff --git a/example/cpp03/http/server2/io_context_pool.cpp b/example/cpp03/http/server2/io_context_pool.cpp
new file mode 100644
index 0000000000..ed47b75569
--- /dev/null
+++ b/example/cpp03/http/server2/io_context_pool.cpp
@@ -0,0 +1,70 @@
+//
+// io_context_pool.cpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "server.hpp"
+#include <stdexcept>
+#include <boost/thread/thread.hpp>
+#include <boost/bind.hpp>
+#include <boost/shared_ptr.hpp>
+
+namespace http {
+namespace server2 {
+
+io_context_pool::io_context_pool(std::size_t pool_size)
+  : next_io_context_(0)
+{
+  if (pool_size == 0)
+    throw std::runtime_error("io_context_pool size is 0");
+
+  // Give all the io_contexts work to do so that their run() functions will not
+  // exit until they are explicitly stopped.
+  for (std::size_t i = 0; i < pool_size; ++i)
+  {
+    io_context_ptr io_context(new boost::asio::io_context);
+    io_contexts_.push_back(io_context);
+    work_.push_back(boost::asio::make_work_guard(*io_context));
+  }
+}
+
+void io_context_pool::run()
+{
+  // Create a pool of threads to run all of the io_contexts.
+  std::vector<boost::shared_ptr<boost::thread> > threads;
+  for (std::size_t i = 0; i < io_contexts_.size(); ++i)
+  {
+    boost::shared_ptr<boost::thread> thread(new boost::thread(
+          boost::bind(&boost::asio::io_context::run, io_contexts_[i])));
+    threads.push_back(thread);
+  }
+
+  // Wait for all threads in the pool to exit.
+  for (std::size_t i = 0; i < threads.size(); ++i)
+    threads[i]->join();
+}
+
+void io_context_pool::stop()
+{
+  // Explicitly stop all io_contexts.
+  for (std::size_t i = 0; i < io_contexts_.size(); ++i)
+    io_contexts_[i]->stop();
+}
+
+boost::asio::io_context& io_context_pool::get_io_context()
+{
+  // Use a round-robin scheme to choose the next io_context to use.
+  boost::asio::io_context& io_context = *io_contexts_[next_io_context_];
+  ++next_io_context_;
+  if (next_io_context_ == io_contexts_.size())
+    next_io_context_ = 0;
+  return io_context;
+}
+
+} // namespace server2
+} // namespace http
diff --git a/example/cpp03/http/server2/io_context_pool.hpp b/example/cpp03/http/server2/io_context_pool.hpp
new file mode 100644
index 0000000000..7af524a077
--- /dev/null
+++ b/example/cpp03/http/server2/io_context_pool.hpp
@@ -0,0 +1,58 @@
+//
+// io_context_pool.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_IO_SERVICE_POOL_HPP
+#define HTTP_SERVER2_IO_SERVICE_POOL_HPP
+
+#include <boost/asio.hpp>
+#include <list>
+#include <vector>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+
+namespace http {
+namespace server2 {
+
+/// A pool of io_context objects.
+class io_context_pool
+  : private boost::noncopyable
+{
+public:
+  /// Construct the io_context pool.
+  explicit io_context_pool(std::size_t pool_size);
+
+  /// Run all io_context objects in the pool.
+  void run();
+
+  /// Stop all io_context objects in the pool.
+  void stop();
+
+  /// Get an io_context to use.
+  boost::asio::io_context& get_io_context();
+
+private:
+  typedef boost::shared_ptr<boost::asio::io_context> io_context_ptr;
+  typedef boost::asio::executor_work_guard<
+    boost::asio::io_context::executor_type> io_context_work;
+
+  /// The pool of io_contexts.
+  std::vector<io_context_ptr> io_contexts_;
+
+  /// The work that keeps the io_contexts running.
+  std::list<io_context_work> work_;
+
+  /// The next io_context to use for a connection.
+  std::size_t next_io_context_;
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_IO_SERVICE_POOL_HPP
diff --git a/example/cpp03/http/server2/io_service_pool.cpp b/example/cpp03/http/server2/io_service_pool.cpp
deleted file mode 100644
index 9b948b8ddb..0000000000
--- a/example/cpp03/http/server2/io_service_pool.cpp
+++ /dev/null
@@ -1,71 +0,0 @@
-//
-// io_service_pool.cpp
-// ~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#include "server.hpp"
-#include <stdexcept>
-#include <boost/thread/thread.hpp>
-#include <boost/bind.hpp>
-#include <boost/shared_ptr.hpp>
-
-namespace http {
-namespace server2 {
-
-io_service_pool::io_service_pool(std::size_t pool_size)
-  : next_io_service_(0)
-{
-  if (pool_size == 0)
-    throw std::runtime_error("io_service_pool size is 0");
-
-  // Give all the io_services work to do so that their run() functions will not
-  // exit until they are explicitly stopped.
-  for (std::size_t i = 0; i < pool_size; ++i)
-  {
-    io_service_ptr io_service(new boost::asio::io_service);
-    work_ptr work(new boost::asio::io_service::work(*io_service));
-    io_services_.push_back(io_service);
-    work_.push_back(work);
-  }
-}
-
-void io_service_pool::run()
-{
-  // Create a pool of threads to run all of the io_services.
-  std::vector<boost::shared_ptr<boost::thread> > threads;
-  for (std::size_t i = 0; i < io_services_.size(); ++i)
-  {
-    boost::shared_ptr<boost::thread> thread(new boost::thread(
-          boost::bind(&boost::asio::io_service::run, io_services_[i])));
-    threads.push_back(thread);
-  }
-
-  // Wait for all threads in the pool to exit.
-  for (std::size_t i = 0; i < threads.size(); ++i)
-    threads[i]->join();
-}
-
-void io_service_pool::stop()
-{
-  // Explicitly stop all io_services.
-  for (std::size_t i = 0; i < io_services_.size(); ++i)
-    io_services_[i]->stop();
-}
-
-boost::asio::io_service& io_service_pool::get_io_service()
-{
-  // Use a round-robin scheme to choose the next io_service to use.
-  boost::asio::io_service& io_service = *io_services_[next_io_service_];
-  ++next_io_service_;
-  if (next_io_service_ == io_services_.size())
-    next_io_service_ = 0;
-  return io_service;
-}
-
-} // namespace server2
-} // namespace http
diff --git a/example/cpp03/http/server2/io_service_pool.hpp b/example/cpp03/http/server2/io_service_pool.hpp
deleted file mode 100644
index a0031388dc..0000000000
--- a/example/cpp03/http/server2/io_service_pool.hpp
+++ /dev/null
@@ -1,56 +0,0 @@
-//
-// io_service_pool.hpp
-// ~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef HTTP_SERVER2_IO_SERVICE_POOL_HPP
-#define HTTP_SERVER2_IO_SERVICE_POOL_HPP
-
-#include <boost/asio.hpp>
-#include <vector>
-#include <boost/noncopyable.hpp>
-#include <boost/shared_ptr.hpp>
-
-namespace http {
-namespace server2 {
-
-/// A pool of io_service objects.
-class io_service_pool
-  : private boost::noncopyable
-{
-public:
-  /// Construct the io_service pool.
-  explicit io_service_pool(std::size_t pool_size);
-
-  /// Run all io_service objects in the pool.
-  void run();
-
-  /// Stop all io_service objects in the pool.
-  void stop();
-
-  /// Get an io_service to use.
-  boost::asio::io_service& get_io_service();
-
-private:
-  typedef boost::shared_ptr<boost::asio::io_service> io_service_ptr;
-  typedef boost::shared_ptr<boost::asio::io_service::work> work_ptr;
-
-  /// The pool of io_services.
-  std::vector<io_service_ptr> io_services_;
-
-  /// The work that keeps the io_services running.
-  std::vector<work_ptr> work_;
-
-  /// The next io_service to use for a connection.
-  std::size_t next_io_service_;
-};
-
-} // namespace server2
-} // namespace http
-
-#endif // HTTP_SERVER2_IO_SERVICE_POOL_HPP
diff --git a/example/cpp03/http/server2/server.cpp b/example/cpp03/http/server2/server.cpp
index c3504d2764..d3bfa58ea7 100644
--- a/example/cpp03/http/server2/server.cpp
+++ b/example/cpp03/http/server2/server.cpp
@@ -15,10 +15,10 @@ namespace http {
 namespace server2 {
 
 server::server(const std::string& address, const std::string& port,
-    const std::string& doc_root, std::size_t io_service_pool_size)
-  : io_service_pool_(io_service_pool_size),
-    signals_(io_service_pool_.get_io_service()),
-    acceptor_(io_service_pool_.get_io_service()),
+    const std::string& doc_root, std::size_t io_context_pool_size)
+  : io_context_pool_(io_context_pool_size),
+    signals_(io_context_pool_.get_io_context()),
+    acceptor_(io_context_pool_.get_io_context()),
     new_connection_(),
     request_handler_(doc_root)
 {
@@ -33,9 +33,9 @@ server::server(const std::string& address, const std::string& port,
   signals_.async_wait(boost::bind(&server::handle_stop, this));
 
   // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
-  boost::asio::ip::tcp::resolver resolver(acceptor_.get_io_service());
-  boost::asio::ip::tcp::resolver::query query(address, port);
-  boost::asio::ip::tcp::endpoint endpoint = *resolver.resolve(query);
+  boost::asio::ip::tcp::resolver resolver(acceptor_.get_executor().context());
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
   acceptor_.open(endpoint.protocol());
   acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
   acceptor_.bind(endpoint);
@@ -46,13 +46,13 @@ server::server(const std::string& address, const std::string& port,
 
 void server::run()
 {
-  io_service_pool_.run();
+  io_context_pool_.run();
 }
 
 void server::start_accept()
 {
   new_connection_.reset(new connection(
-        io_service_pool_.get_io_service(), request_handler_));
+        io_context_pool_.get_io_context(), request_handler_));
   acceptor_.async_accept(new_connection_->socket(),
       boost::bind(&server::handle_accept, this,
         boost::asio::placeholders::error));
@@ -70,7 +70,7 @@ void server::handle_accept(const boost::system::error_code& e)
 
 void server::handle_stop()
 {
-  io_service_pool_.stop();
+  io_context_pool_.stop();
 }
 
 } // namespace server2
diff --git a/example/cpp03/http/server2/server.hpp b/example/cpp03/http/server2/server.hpp
index 412a00cee1..a35415b5e0 100644
--- a/example/cpp03/http/server2/server.hpp
+++ b/example/cpp03/http/server2/server.hpp
@@ -17,7 +17,7 @@
 #include <boost/noncopyable.hpp>
 #include <boost/shared_ptr.hpp>
 #include "connection.hpp"
-#include "io_service_pool.hpp"
+#include "io_context_pool.hpp"
 #include "request_handler.hpp"
 
 namespace http {
@@ -31,9 +31,9 @@ class server
   /// Construct the server to listen on the specified TCP address and port, and
   /// serve up files from the given directory.
   explicit server(const std::string& address, const std::string& port,
-      const std::string& doc_root, std::size_t io_service_pool_size);
+      const std::string& doc_root, std::size_t io_context_pool_size);
 
-  /// Run the server's io_service loop.
+  /// Run the server's io_context loop.
   void run();
 
 private:
@@ -46,8 +46,8 @@ class server
   /// Handle a request to stop the server.
   void handle_stop();
 
-  /// The pool of io_service objects used to perform asynchronous operations.
-  io_service_pool io_service_pool_;
+  /// The pool of io_context objects used to perform asynchronous operations.
+  io_context_pool io_context_pool_;
 
   /// The signal_set is used to register for process termination notifications.
   boost::asio::signal_set signals_;
diff --git a/example/cpp03/http/server3/connection.cpp b/example/cpp03/http/server3/connection.cpp
index 5f77f03752..37890b570d 100644
--- a/example/cpp03/http/server3/connection.cpp
+++ b/example/cpp03/http/server3/connection.cpp
@@ -16,10 +16,10 @@
 namespace http {
 namespace server3 {
 
-connection::connection(boost::asio::io_service& io_service,
+connection::connection(boost::asio::io_context& io_context,
     request_handler& handler)
-  : strand_(io_service),
-    socket_(io_service),
+  : strand_(io_context),
+    socket_(io_context),
     request_handler_(handler)
 {
 }
@@ -32,7 +32,7 @@ boost::asio::ip::tcp::socket& connection::socket()
 void connection::start()
 {
   socket_.async_read_some(boost::asio::buffer(buffer_),
-      strand_.wrap(
+      boost::asio::bind_executor(strand_,
         boost::bind(&connection::handle_read, shared_from_this(),
           boost::asio::placeholders::error,
           boost::asio::placeholders::bytes_transferred)));
@@ -51,7 +51,7 @@ void connection::handle_read(const boost::system::error_code& e,
     {
       request_handler_.handle_request(request_, reply_);
       boost::asio::async_write(socket_, reply_.to_buffers(),
-          strand_.wrap(
+          boost::asio::bind_executor(strand_,
             boost::bind(&connection::handle_write, shared_from_this(),
               boost::asio::placeholders::error)));
     }
@@ -59,14 +59,14 @@ void connection::handle_read(const boost::system::error_code& e,
     {
       reply_ = reply::stock_reply(reply::bad_request);
       boost::asio::async_write(socket_, reply_.to_buffers(),
-          strand_.wrap(
+          boost::asio::bind_executor(strand_,
             boost::bind(&connection::handle_write, shared_from_this(),
               boost::asio::placeholders::error)));
     }
     else
     {
       socket_.async_read_some(boost::asio::buffer(buffer_),
-          strand_.wrap(
+          boost::asio::bind_executor(strand_,
             boost::bind(&connection::handle_read, shared_from_this(),
               boost::asio::placeholders::error,
               boost::asio::placeholders::bytes_transferred)));
diff --git a/example/cpp03/http/server3/connection.hpp b/example/cpp03/http/server3/connection.hpp
index e552c4a38c..420dd0e743 100644
--- a/example/cpp03/http/server3/connection.hpp
+++ b/example/cpp03/http/server3/connection.hpp
@@ -30,8 +30,8 @@ class connection
     private boost::noncopyable
 {
 public:
-  /// Construct a connection with the given io_service.
-  explicit connection(boost::asio::io_service& io_service,
+  /// Construct a connection with the given io_context.
+  explicit connection(boost::asio::io_context& io_context,
       request_handler& handler);
 
   /// Get the socket associated with the connection.
@@ -49,7 +49,7 @@ class connection
   void handle_write(const boost::system::error_code& e);
 
   /// Strand to ensure the connection's handlers are not called concurrently.
-  boost::asio::io_service::strand strand_;
+  boost::asio::io_context::strand strand_;
 
   /// Socket for the connection.
   boost::asio::ip::tcp::socket socket_;
diff --git a/example/cpp03/http/server3/server.cpp b/example/cpp03/http/server3/server.cpp
index 3ce54d736c..fc1c651686 100644
--- a/example/cpp03/http/server3/server.cpp
+++ b/example/cpp03/http/server3/server.cpp
@@ -20,8 +20,8 @@ namespace server3 {
 server::server(const std::string& address, const std::string& port,
     const std::string& doc_root, std::size_t thread_pool_size)
   : thread_pool_size_(thread_pool_size),
-    signals_(io_service_),
-    acceptor_(io_service_),
+    signals_(io_context_),
+    acceptor_(io_context_),
     new_connection_(),
     request_handler_(doc_root)
 {
@@ -36,9 +36,9 @@ server::server(const std::string& address, const std::string& port,
   signals_.async_wait(boost::bind(&server::handle_stop, this));
 
   // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
-  boost::asio::ip::tcp::resolver resolver(io_service_);
-  boost::asio::ip::tcp::resolver::query query(address, port);
-  boost::asio::ip::tcp::endpoint endpoint = *resolver.resolve(query);
+  boost::asio::ip::tcp::resolver resolver(io_context_);
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
   acceptor_.open(endpoint.protocol());
   acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
   acceptor_.bind(endpoint);
@@ -49,12 +49,12 @@ server::server(const std::string& address, const std::string& port,
 
 void server::run()
 {
-  // Create a pool of threads to run all of the io_services.
+  // Create a pool of threads to run all of the io_contexts.
   std::vector<boost::shared_ptr<boost::thread> > threads;
   for (std::size_t i = 0; i < thread_pool_size_; ++i)
   {
     boost::shared_ptr<boost::thread> thread(new boost::thread(
-          boost::bind(&boost::asio::io_service::run, &io_service_)));
+          boost::bind(&boost::asio::io_context::run, &io_context_)));
     threads.push_back(thread);
   }
 
@@ -65,7 +65,7 @@ void server::run()
 
 void server::start_accept()
 {
-  new_connection_.reset(new connection(io_service_, request_handler_));
+  new_connection_.reset(new connection(io_context_, request_handler_));
   acceptor_.async_accept(new_connection_->socket(),
       boost::bind(&server::handle_accept, this,
         boost::asio::placeholders::error));
@@ -83,7 +83,7 @@ void server::handle_accept(const boost::system::error_code& e)
 
 void server::handle_stop()
 {
-  io_service_.stop();
+  io_context_.stop();
 }
 
 } // namespace server3
diff --git a/example/cpp03/http/server3/server.hpp b/example/cpp03/http/server3/server.hpp
index 5ff6bf3c4f..8f1b1c20af 100644
--- a/example/cpp03/http/server3/server.hpp
+++ b/example/cpp03/http/server3/server.hpp
@@ -32,7 +32,7 @@ class server
   explicit server(const std::string& address, const std::string& port,
       const std::string& doc_root, std::size_t thread_pool_size);
 
-  /// Run the server's io_service loop.
+  /// Run the server's io_context loop.
   void run();
 
 private:
@@ -45,11 +45,11 @@ class server
   /// Handle a request to stop the server.
   void handle_stop();
 
-  /// The number of threads that will call io_service::run().
+  /// The number of threads that will call io_context::run().
   std::size_t thread_pool_size_;
 
-  /// The io_service used to perform asynchronous operations.
-  boost::asio::io_service io_service_;
+  /// The io_context used to perform asynchronous operations.
+  boost::asio::io_context io_context_;
 
   /// The signal_set is used to register for process termination notifications.
   boost::asio::signal_set signals_;
diff --git a/example/cpp03/http/server4/main.cpp b/example/cpp03/http/server4/main.cpp
index 48c3ec516c..449ffa3a3e 100644
--- a/example/cpp03/http/server4/main.cpp
+++ b/example/cpp03/http/server4/main.cpp
@@ -30,24 +30,24 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     // Launch the initial server coroutine.
-    http::server4::server(io_service, argv[1], argv[2],
+    http::server4::server(io_context, argv[1], argv[2],
         http::server4::file_handler(argv[3]))();
 
     // Wait for signals indicating time to shut down.
-    boost::asio::signal_set signals(io_service);
+    boost::asio::signal_set signals(io_context);
     signals.add(SIGINT);
     signals.add(SIGTERM);
 #if defined(SIGQUIT)
     signals.add(SIGQUIT);
 #endif // defined(SIGQUIT)
     signals.async_wait(boost::bind(
-          &boost::asio::io_service::stop, &io_service));
+          &boost::asio::io_context::stop, &io_context));
 
     // Run the server.
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/http/server4/server.cpp b/example/cpp03/http/server4/server.cpp
index 66aa329339..080fa345b9 100644
--- a/example/cpp03/http/server4/server.cpp
+++ b/example/cpp03/http/server4/server.cpp
@@ -15,14 +15,15 @@
 namespace http {
 namespace server4 {
 
-server::server(boost::asio::io_service& io_service,
+server::server(boost::asio::io_context& io_context,
     const std::string& address, const std::string& port,
     boost::function<void(const request&, reply&)> request_handler)
   : request_handler_(request_handler)
 {
-  tcp::resolver resolver(io_service);
-  tcp::resolver::query query(address, port);
-  acceptor_.reset(new tcp::acceptor(io_service, *resolver.resolve(query)));
+  tcp::resolver resolver(io_context);
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
+  acceptor_.reset(new tcp::acceptor(io_context, endpoint));
 }
 
 // Enable the pseudo-keywords reenter, yield and fork.
@@ -44,12 +45,12 @@ void server::operator()(boost::system::error_code ec, std::size_t length)
       do
       {
         // Create a new socket for the next incoming connection.
-        socket_.reset(new tcp::socket(acceptor_->get_io_service()));
+        socket_.reset(new tcp::socket(acceptor_->get_executor().context()));
 
         // Accept a new connection. The "yield" pseudo-keyword saves the current
         // line number and exits the coroutine's "reenter" block. We use the
         // server coroutine as the completion handler for the async_accept
-        // operation. When the asynchronous operation completes, the io_service
+        // operation. When the asynchronous operation completes, the io_context
         // invokes the function call operator, we "reenter" the coroutine, and
         // then control resumes at the following line.
         yield acceptor_->async_accept(*socket_, *this);
diff --git a/example/cpp03/http/server4/server.hpp b/example/cpp03/http/server4/server.hpp
index 7d01701af9..3ef3b68a9b 100644
--- a/example/cpp03/http/server4/server.hpp
+++ b/example/cpp03/http/server4/server.hpp
@@ -30,7 +30,7 @@ class server : boost::asio::coroutine
 public:
   /// Construct the server to listen on the specified TCP address and port, and
   /// serve up files from the given directory.
-  explicit server(boost::asio::io_service& io_service,
+  explicit server(boost::asio::io_context& io_context,
       const std::string& address, const std::string& port,
       boost::function<void(const request&, reply&)> request_handler);
 
diff --git a/example/cpp03/icmp/ping.cpp b/example/cpp03/icmp/ping.cpp
index a9aa57f808..4daf81948b 100644
--- a/example/cpp03/icmp/ping.cpp
+++ b/example/cpp03/icmp/ping.cpp
@@ -24,12 +24,11 @@ namespace posix_time = boost::posix_time;
 class pinger
 {
 public:
-  pinger(boost::asio::io_service& io_service, const char* destination)
-    : resolver_(io_service), socket_(io_service, icmp::v4()),
-      timer_(io_service), sequence_number_(0), num_replies_(0)
+  pinger(boost::asio::io_context& io_context, const char* destination)
+    : resolver_(io_context), socket_(io_context, icmp::v4()),
+      timer_(io_context), sequence_number_(0), num_replies_(0)
   {
-    icmp::resolver::query query(icmp::v4(), destination, "");
-    destination_ = *resolver_.resolve(query);
+    destination_ = *resolver_.resolve(icmp::v4(), destination, "").begin();
 
     start_send();
     start_receive();
@@ -151,9 +150,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
-    pinger p(io_service, argv[1]);
-    io_service.run();
+    boost::asio::io_context io_context;
+    pinger p(io_context, argv[1]);
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/invocation/prioritised_handlers.cpp b/example/cpp03/invocation/prioritised_handlers.cpp
index 67ffee545a..ebf8483e81 100644
--- a/example/cpp03/invocation/prioritised_handlers.cpp
+++ b/example/cpp03/invocation/prioritised_handlers.cpp
@@ -127,32 +127,32 @@ void low_priority_handler()
 
 int main()
 {
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
   handler_priority_queue pri_queue;
 
   // Post a completion handler to be run immediately.
-  io_service.post(pri_queue.wrap(0, low_priority_handler));
+  boost::asio::post(io_context, pri_queue.wrap(0, low_priority_handler));
 
   // Start an asynchronous accept that will complete immediately.
   tcp::endpoint endpoint(boost::asio::ip::address_v4::loopback(), 0);
-  tcp::acceptor acceptor(io_service, endpoint);
-  tcp::socket server_socket(io_service);
+  tcp::acceptor acceptor(io_context, endpoint);
+  tcp::socket server_socket(io_context);
   acceptor.async_accept(server_socket,
       pri_queue.wrap(100, high_priority_handler));
-  tcp::socket client_socket(io_service);
+  tcp::socket client_socket(io_context);
   client_socket.connect(acceptor.local_endpoint());
 
   // Set a deadline timer to expire immediately.
-  boost::asio::deadline_timer timer(io_service);
+  boost::asio::deadline_timer timer(io_context);
   timer.expires_at(boost::posix_time::neg_infin);
   timer.async_wait(pri_queue.wrap(42, middle_priority_handler));
 
-  while (io_service.run_one())
+  while (io_context.run_one())
   {
     // The custom invocation hook adds the handlers to the priority queue
     // rather than executing them from within the poll_one() call.
-    while (io_service.poll_one())
+    while (io_context.poll_one())
       ;
 
     pri_queue.execute_all();
diff --git a/example/cpp03/iostreams/daytime_server.cpp b/example/cpp03/iostreams/daytime_server.cpp
index 7d7c3f0889..3e0356c79b 100644
--- a/example/cpp03/iostreams/daytime_server.cpp
+++ b/example/cpp03/iostreams/daytime_server.cpp
@@ -26,16 +26,16 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     tcp::endpoint endpoint(tcp::v4(), 13);
-    tcp::acceptor acceptor(io_service, endpoint);
+    tcp::acceptor acceptor(io_context, endpoint);
 
     for (;;)
     {
       tcp::iostream stream;
       boost::system::error_code ec;
-      acceptor.accept(*stream.rdbuf(), ec);
+      acceptor.accept(stream.socket(), ec);
       if (!ec)
       {
         stream << make_daytime_string();
diff --git a/example/cpp03/iostreams/http_client.cpp b/example/cpp03/iostreams/http_client.cpp
index 5f2bfc8736..52842abfd7 100644
--- a/example/cpp03/iostreams/http_client.cpp
+++ b/example/cpp03/iostreams/http_client.cpp
@@ -1,5 +1,5 @@
 //
-// sync_client.cpp
+// http_client.cpp
 // ~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
@@ -33,7 +33,7 @@ int main(int argc, char* argv[])
     // The entire sequence of I/O operations must complete within 60 seconds.
     // If an expiry occurs, the socket is automatically closed and the stream
     // becomes bad.
-    s.expires_from_now(boost::posix_time::seconds(60));
+    s.expires_after(boost::posix_time::seconds(60));
 
     // Establish a connection to the server.
     s.connect(argv[1], "http");
diff --git a/example/cpp03/local/connect_pair.cpp b/example/cpp03/local/connect_pair.cpp
index 1d8a7f3196..934731b710 100644
--- a/example/cpp03/local/connect_pair.cpp
+++ b/example/cpp03/local/connect_pair.cpp
@@ -23,8 +23,8 @@ using boost::asio::local::stream_protocol;
 class uppercase_filter
 {
 public:
-  uppercase_filter(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  uppercase_filter(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -82,11 +82,11 @@ class uppercase_filter
   boost::array<char, 512> data_;
 };
 
-void run(boost::asio::io_service* io_service)
+void run(boost::asio::io_context* io_context)
 {
   try
   {
-    io_service->run();
+    io_context->run();
   }
   catch (std::exception& e)
   {
@@ -99,16 +99,16 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     // Create filter and establish a connection to it.
-    uppercase_filter filter(io_service);
-    stream_protocol::socket socket(io_service);
+    uppercase_filter filter(io_context);
+    stream_protocol::socket socket(io_context);
     boost::asio::local::connect_pair(socket, filter.socket());
     filter.start();
 
-    // The io_service runs in a background thread to perform filtering.
-    boost::thread thread(boost::bind(run, &io_service));
+    // The io_context runs in a background thread to perform filtering.
+    boost::thread thread(boost::bind(run, &io_context));
 
     for (;;)
     {
diff --git a/example/cpp03/local/stream_client.cpp b/example/cpp03/local/stream_client.cpp
index f0f7b978ca..915cbe2f3f 100644
--- a/example/cpp03/local/stream_client.cpp
+++ b/example/cpp03/local/stream_client.cpp
@@ -29,9 +29,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    stream_protocol::socket s(io_service);
+    stream_protocol::socket s(io_context);
     s.connect(stream_protocol::endpoint(argv[1]));
 
     using namespace std; // For strlen.
diff --git a/example/cpp03/local/stream_server.cpp b/example/cpp03/local/stream_server.cpp
index a376a82139..05194240c3 100644
--- a/example/cpp03/local/stream_server.cpp
+++ b/example/cpp03/local/stream_server.cpp
@@ -24,8 +24,8 @@ class session
   : public boost::enable_shared_from_this<session>
 {
 public:
-  session(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -81,11 +81,11 @@ typedef boost::shared_ptr<session> session_ptr;
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, const std::string& file)
-    : io_service_(io_service),
-      acceptor_(io_service, stream_protocol::endpoint(file))
+  server(boost::asio::io_context& io_context, const std::string& file)
+    : io_context_(io_context),
+      acceptor_(io_context, stream_protocol::endpoint(file))
   {
-    session_ptr new_session(new session(io_service_));
+    session_ptr new_session(new session(io_context_));
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
@@ -99,14 +99,14 @@ class server
       new_session->start();
     }
 
-    new_session.reset(new session(io_service_));
+    new_session.reset(new session(io_context_));
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   stream_protocol::acceptor acceptor_;
 };
 
@@ -121,12 +121,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     std::remove(argv[1]);
-    server s(io_service, argv[1]);
+    server s(io_context, argv[1]);
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/multicast/receiver.cpp b/example/cpp03/multicast/receiver.cpp
index da98a5f21c..ed9d5ccb27 100644
--- a/example/cpp03/multicast/receiver.cpp
+++ b/example/cpp03/multicast/receiver.cpp
@@ -18,10 +18,10 @@ const short multicast_port = 30001;
 class receiver
 {
 public:
-  receiver(boost::asio::io_service& io_service,
+  receiver(boost::asio::io_context& io_context,
       const boost::asio::ip::address& listen_address,
       const boost::asio::ip::address& multicast_address)
-    : socket_(io_service)
+    : socket_(io_context)
   {
     // Create the socket so that multiple may be bound to the same address.
     boost::asio::ip::udp::endpoint listen_endpoint(
@@ -78,11 +78,11 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
-    receiver r(io_service,
-        boost::asio::ip::address::from_string(argv[1]),
-        boost::asio::ip::address::from_string(argv[2]));
-    io_service.run();
+    boost::asio::io_context io_context;
+    receiver r(io_context,
+        boost::asio::ip::make_address(argv[1]),
+        boost::asio::ip::make_address(argv[2]));
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/multicast/sender.cpp b/example/cpp03/multicast/sender.cpp
index 42e763429c..15267248b4 100644
--- a/example/cpp03/multicast/sender.cpp
+++ b/example/cpp03/multicast/sender.cpp
@@ -21,11 +21,11 @@ const int max_message_count = 10;
 class sender
 {
 public:
-  sender(boost::asio::io_service& io_service,
+  sender(boost::asio::io_context& io_context,
       const boost::asio::ip::address& multicast_address)
     : endpoint_(multicast_address, multicast_port),
-      socket_(io_service, endpoint_.protocol()),
-      timer_(io_service),
+      socket_(io_context, endpoint_.protocol()),
+      timer_(io_context),
       message_count_(0)
   {
     std::ostringstream os;
@@ -86,9 +86,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
-    sender s(io_service, boost::asio::ip::address::from_string(argv[1]));
-    io_service.run();
+    boost::asio::io_context io_context;
+    sender s(io_context, boost::asio::ip::make_address(argv[1]));
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/nonblocking/third_party_lib.cpp b/example/cpp03/nonblocking/third_party_lib.cpp
index cbaef56e2c..6ace6d8c63 100644
--- a/example/cpp03/nonblocking/third_party_lib.cpp
+++ b/example/cpp03/nonblocking/third_party_lib.cpp
@@ -83,9 +83,9 @@ class connection
 public:
   typedef boost::shared_ptr<connection> pointer;
 
-  static pointer create(boost::asio::io_service& io_service)
+  static pointer create(boost::asio::io_context& io_context)
   {
-    return pointer(new connection(io_service));
+    return pointer(new connection(io_context));
   }
 
   tcp::socket& socket()
@@ -102,8 +102,8 @@ class connection
   }
 
 private:
-  connection(boost::asio::io_service& io_service)
-    : socket_(io_service),
+  connection(boost::asio::io_context& io_context)
+    : socket_(io_context),
       session_impl_(socket_),
       read_in_progress_(false),
       write_in_progress_(false)
@@ -116,8 +116,7 @@ class connection
     if (session_impl_.want_read() && !read_in_progress_)
     {
       read_in_progress_ = true;
-      socket_.async_read_some(
-          boost::asio::null_buffers(),
+      socket_.async_wait(tcp::socket::wait_read,
           boost::bind(&connection::handle_read,
             shared_from_this(),
             boost::asio::placeholders::error));
@@ -127,8 +126,7 @@ class connection
     if (session_impl_.want_write() && !write_in_progress_)
     {
       write_in_progress_ = true;
-      socket_.async_write_some(
-          boost::asio::null_buffers(),
+      socket_.async_wait(tcp::socket::wait_write,
           boost::bind(&connection::handle_write,
             shared_from_this(),
             boost::asio::placeholders::error));
@@ -185,8 +183,8 @@ class connection
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, unsigned short port)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
   {
     start_accept();
   }
@@ -195,7 +193,7 @@ class server
   void start_accept()
   {
     connection::pointer new_connection =
-      connection::create(acceptor_.get_io_service());
+      connection::create(acceptor_.get_executor().context());
 
     acceptor_.async_accept(new_connection->socket(),
         boost::bind(&server::handle_accept, this, new_connection,
@@ -226,12 +224,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/porthopper/client.cpp b/example/cpp03/porthopper/client.cpp
index ba607a7054..05c020cd75 100644
--- a/example/cpp03/porthopper/client.cpp
+++ b/example/cpp03/porthopper/client.cpp
@@ -37,20 +37,19 @@ int main(int argc, char* argv[])
     std::string host_name = argv[1];
     std::string port = argv[2];
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     // Determine the location of the server.
-    tcp::resolver resolver(io_service);
-    tcp::resolver::query query(host_name, port);
-    tcp::endpoint remote_endpoint = *resolver.resolve(query);
+    tcp::resolver resolver(io_context);
+    tcp::endpoint remote_endpoint = *resolver.resolve(host_name, port).begin();
 
     // Establish the control connection to the server.
-    tcp::socket control_socket(io_service);
+    tcp::socket control_socket(io_context);
     control_socket.connect(remote_endpoint);
 
     // Create a datagram socket to receive data from the server.
     boost::shared_ptr<udp::socket> data_socket(
-        new udp::socket(io_service, udp::endpoint(udp::v4(), 0)));
+        new udp::socket(io_context, udp::endpoint(udp::v4(), 0)));
 
     // Determine what port we will receive data on.
     udp::endpoint data_endpoint = data_socket->local_endpoint();
@@ -82,7 +81,7 @@ int main(int argc, char* argv[])
 
       // Create the new data socket.
       boost::shared_ptr<udp::socket> new_data_socket(
-          new udp::socket(io_service, udp::endpoint(udp::v4(), 0)));
+          new udp::socket(io_context, udp::endpoint(udp::v4(), 0)));
 
       // Determine the new port we will use to receive data.
       udp::endpoint new_data_endpoint = new_data_socket->local_endpoint();
@@ -126,7 +125,7 @@ int main(int argc, char* argv[])
         // Even though we're performing a renegotation, we want to continue
         // receiving data as smoothly as possible. Therefore we will continue to
         // try to receive a frame from the server on the old data socket. If we
-        // receive a frame on this socket we will interrupt the io_service,
+        // receive a frame on this socket we will interrupt the io_context,
         // print the frame, and resume waiting for the other operations to
         // complete.
         frame f2;
@@ -138,19 +137,19 @@ int main(int argc, char* argv[])
                 lambda::if_(!lambda::_1)
                 [
                   // We have successfully received a frame on the old data
-                  // socket. Stop the io_service so that we can print it.
-                  lambda::bind(&boost::asio::io_service::stop, &io_service),
+                  // socket. Stop the io_context so that we can print it.
+                  lambda::bind(&boost::asio::io_context::stop, &io_context),
                   lambda::var(done) = false
                 ]
               ));
         }
 
         // Run the operations in parallel. This will block until all operations
-        // have finished, or until the io_service is interrupted. (No threads!)
-        io_service.reset();
-        io_service.run();
+        // have finished, or until the io_context is interrupted. (No threads!)
+        io_context.restart();
+        io_context.run();
 
-        // If the io_service.run() was interrupted then we have received a frame
+        // If the io_context.run() was interrupted then we have received a frame
         // on the old data socket. We need to keep waiting for the renegotation
         // operations to complete.
         if (!done)
diff --git a/example/cpp03/porthopper/server.cpp b/example/cpp03/porthopper/server.cpp
index 0fdc7e011b..0426c365be 100644
--- a/example/cpp03/porthopper/server.cpp
+++ b/example/cpp03/porthopper/server.cpp
@@ -29,14 +29,15 @@ class server
 {
 public:
   // Construct the server to wait for incoming control connections.
-  server(boost::asio::io_service& io_service, unsigned short port)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
-      timer_(io_service),
-      udp_socket_(io_service, udp::endpoint(udp::v4(), 0)),
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port)),
+      timer_(io_context),
+      udp_socket_(io_context, udp::endpoint(udp::v4(), 0)),
       next_frame_number_(1)
   {
     // Start waiting for a new control connection.
-    tcp_socket_ptr new_socket(new tcp::socket(acceptor_.get_io_service()));
+    tcp_socket_ptr new_socket(
+        new tcp::socket(acceptor_.get_executor().context()));
     acceptor_.async_accept(*new_socket,
         boost::bind(&server::handle_accept, this,
           boost::asio::placeholders::error, new_socket));
@@ -59,7 +60,8 @@ class server
     }
 
     // Start waiting for a new control connection.
-    tcp_socket_ptr new_socket(new tcp::socket(acceptor_.get_io_service()));
+    tcp_socket_ptr new_socket(
+        new tcp::socket(acceptor_.get_executor().context()));
     acceptor_.async_accept(*new_socket,
         boost::bind(&server::handle_accept, this,
           boost::asio::placeholders::error, new_socket));
@@ -73,7 +75,7 @@ class server
     {
       // Delay handling of the control request to simulate network latency.
       timer_ptr delay_timer(
-          new boost::asio::deadline_timer(acceptor_.get_io_service()));
+          new boost::asio::deadline_timer(acceptor_.get_executor().context()));
       delay_timer->expires_from_now(boost::posix_time::seconds(2));
       delay_timer->async_wait(
           boost::bind(&server::handle_control_request_timer, this,
@@ -171,12 +173,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/serialization/client.cpp b/example/cpp03/serialization/client.cpp
index 2d1f609b45..06f3e4c09e 100644
--- a/example/cpp03/serialization/client.cpp
+++ b/example/cpp03/serialization/client.cpp
@@ -23,12 +23,12 @@ class client
 {
 public:
   /// Constructor starts the asynchronous connect operation.
-  client(boost::asio::io_service& io_service,
+  client(boost::asio::io_context& io_context,
       const std::string& host, const std::string& service)
-    : connection_(io_service)
+    : connection_(io_context)
   {
     // Resolve the host name into an IP address.
-    boost::asio::ip::tcp::resolver resolver(io_service);
+    boost::asio::ip::tcp::resolver resolver(io_context);
     boost::asio::ip::tcp::resolver::query query(host, service);
     boost::asio::ip::tcp::resolver::iterator endpoint_iterator =
       resolver.resolve(query);
@@ -54,7 +54,7 @@ class client
     else
     {
       // An error occurred. Log it and return. Since we are not starting a new
-      // operation the io_service will run out of work to do and the client will
+      // operation the io_context will run out of work to do and the client will
       // exit.
       std::cerr << e.message() << std::endl;
     }
@@ -87,7 +87,7 @@ class client
       std::cerr << e.message() << std::endl;
     }
 
-    // Since we are not starting a new operation the io_service will run out of
+    // Since we are not starting a new operation the io_context will run out of
     // work to do and the client will exit.
   }
 
@@ -112,9 +112,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
-    s11n_example::client client(io_service, argv[1], argv[2]);
-    io_service.run();
+    boost::asio::io_context io_context;
+    s11n_example::client client(io_context, argv[1], argv[2]);
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/serialization/connection.hpp b/example/cpp03/serialization/connection.hpp
index 41a24ab224..464abb63f9 100644
--- a/example/cpp03/serialization/connection.hpp
+++ b/example/cpp03/serialization/connection.hpp
@@ -35,8 +35,8 @@ class connection
 {
 public:
   /// Constructor.
-  connection(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  connection(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -65,7 +65,7 @@ class connection
     {
       // Something went wrong, inform the caller.
       boost::system::error_code error(boost::asio::error::invalid_argument);
-      socket_.get_io_service().post(boost::bind(handler, error));
+      socket_.get_io_context().post(boost::bind(handler, error));
       return;
     }
     outbound_header_ = header_stream.str();
diff --git a/example/cpp03/serialization/server.cpp b/example/cpp03/serialization/server.cpp
index 8fd045da80..6fb4881d94 100644
--- a/example/cpp03/serialization/server.cpp
+++ b/example/cpp03/serialization/server.cpp
@@ -25,8 +25,8 @@ class server
 public:
   /// Constructor opens the acceptor and starts waiting for the first incoming
   /// connection.
-  server(boost::asio::io_service& io_service, unsigned short port)
-    : acceptor_(io_service,
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : acceptor_(io_context,
         boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), port))
   {
     // Create the data to be sent to each client.
@@ -55,7 +55,7 @@ class server
     stocks_.push_back(s);
 
     // Start an accept operation for a new connection.
-    connection_ptr new_conn(new connection(acceptor_.get_io_service()));
+    connection_ptr new_conn(new connection(acceptor_.get_io_context()));
     acceptor_.async_accept(new_conn->socket(),
         boost::bind(&server::handle_accept, this,
           boost::asio::placeholders::error, new_conn));
@@ -75,7 +75,7 @@ class server
     }
 
     // Start an accept operation for a new connection.
-    connection_ptr new_conn(new connection(acceptor_.get_io_service()));
+    connection_ptr new_conn(new connection(acceptor_.get_io_context()));
     acceptor_.async_accept(new_conn->socket(),
         boost::bind(&server::handle_accept, this,
           boost::asio::placeholders::error, new_conn));
@@ -110,9 +110,9 @@ int main(int argc, char* argv[])
     }
     unsigned short port = boost::lexical_cast<unsigned short>(argv[1]);
 
-    boost::asio::io_service io_service;
-    s11n_example::server server(io_service, port);
-    io_service.run();
+    boost::asio::io_context io_context;
+    s11n_example::server server(io_context, port);
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/services/basic_logger.hpp b/example/cpp03/services/basic_logger.hpp
index 380fd21500..0f56c2fef8 100644
--- a/example/cpp03/services/basic_logger.hpp
+++ b/example/cpp03/services/basic_logger.hpp
@@ -34,13 +34,13 @@ class basic_logger
   /**
    * This constructor creates a logger.
    *
-   * @param io_service The io_service object used to locate the logger service.
+   * @param io_context The io_context object used to locate the logger service.
    *
    * @param identifier An identifier for this logger.
    */
-  explicit basic_logger(boost::asio::io_service& io_service,
+  explicit basic_logger(boost::asio::io_context& io_context,
       const std::string& identifier)
-    : service_(boost::asio::use_service<Service>(io_service)),
+    : service_(boost::asio::use_service<Service>(io_context)),
       impl_(service_.null())
   {
     service_.create(impl_, identifier);
@@ -52,10 +52,10 @@ class basic_logger
     service_.destroy(impl_);
   }
 
-  /// Get the io_service associated with the object.
-  boost::asio::io_service& get_io_service()
+  /// Get the io_context associated with the object.
+  boost::asio::io_context& get_io_context()
   {
-    return service_.get_io_service();
+    return service_.get_io_context();
   }
 
   /// Set the output file for all logger instances.
diff --git a/example/cpp03/services/daytime_client.cpp b/example/cpp03/services/daytime_client.cpp
index c812063acb..204382a989 100644
--- a/example/cpp03/services/daytime_client.cpp
+++ b/example/cpp03/services/daytime_client.cpp
@@ -12,15 +12,13 @@
 #include <boost/bind.hpp>
 #include <iostream>
 #include "logger.hpp"
-#include "stream_socket_service.hpp"
 
-typedef boost::asio::basic_stream_socket<boost::asio::ip::tcp,
-    services::stream_socket_service<boost::asio::ip::tcp> > debug_stream_socket;
+using boost::asio::ip::tcp;
 
 char read_buffer[1024];
 
 void read_handler(const boost::system::error_code& e,
-    std::size_t bytes_transferred, debug_stream_socket* s)
+    std::size_t bytes_transferred, tcp::socket* s)
 {
   if (!e)
   {
@@ -30,19 +28,33 @@ void read_handler(const boost::system::error_code& e,
         boost::bind(read_handler, boost::asio::placeholders::error,
           boost::asio::placeholders::bytes_transferred, s));
   }
+  else
+  {
+    services::logger logger(s->get_executor().context(), "read_handler");
+
+    std::string msg = "Read error: ";
+    msg += e.message();
+    logger.log(msg);
+  }
 }
 
-void connect_handler(const boost::system::error_code& e, debug_stream_socket* s)
+void connect_handler(const boost::system::error_code& e, tcp::socket* s)
 {
+  services::logger logger(s->get_executor().context(), "connect_handler");
+
   if (!e)
   {
+    logger.log("Connection established");
+
     s->async_read_some(boost::asio::buffer(read_buffer),
         boost::bind(read_handler, boost::asio::placeholders::error,
           boost::asio::placeholders::bytes_transferred, s));
   }
   else
   {
-    std::cerr << e.message() << std::endl;
+    std::string msg = "Unable to establish connection: ";
+    msg += e.message();
+    logger.log(msg);
   }
 }
 
@@ -56,25 +68,25 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     // Set the name of the file that all logger instances will use.
-    services::logger logger(io_service, "");
+    services::logger logger(io_context, "");
     logger.use_file("log.txt");
 
     // Resolve the address corresponding to the given host.
-    boost::asio::ip::tcp::resolver resolver(io_service);
-    boost::asio::ip::tcp::resolver::query query(argv[1], "daytime");
-    boost::asio::ip::tcp::resolver::iterator iterator = resolver.resolve(query);
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints =
+      resolver.resolve(argv[1], "daytime");
 
     // Start an asynchronous connect.
-    debug_stream_socket socket(io_service);
-    boost::asio::async_connect(socket, iterator,
+    tcp::socket socket(io_context);
+    boost::asio::async_connect(socket, endpoints,
         boost::bind(connect_handler,
           boost::asio::placeholders::error, &socket));
 
-    // Run the io_service until all operations have finished.
-    io_service.run();
+    // Run the io_context until all operations have finished.
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/services/logger_service.cpp b/example/cpp03/services/logger_service.cpp
index 23fc764f6b..1324d30745 100644
--- a/example/cpp03/services/logger_service.cpp
+++ b/example/cpp03/services/logger_service.cpp
@@ -12,6 +12,6 @@
 
 namespace services {
 
-boost::asio::io_service::id logger_service::id;
+boost::asio::io_context::id logger_service::id;
 
 } // namespace services
diff --git a/example/cpp03/services/logger_service.hpp b/example/cpp03/services/logger_service.hpp
index d5e76437da..c1eea40333 100644
--- a/example/cpp03/services/logger_service.hpp
+++ b/example/cpp03/services/logger_service.hpp
@@ -25,11 +25,11 @@ namespace services {
 
 /// Service implementation for the logger.
 class logger_service
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 {
 public:
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 
   /// The backend implementation of a logger.
   struct logger_impl
@@ -41,21 +41,21 @@ class logger_service
   /// The type for an implementation of the logger.
   typedef logger_impl* impl_type;
 
-  /// Constructor creates a thread to run a private io_service.
-  logger_service(boost::asio::io_service& io_service)
-    : boost::asio::io_service::service(io_service),
-      work_io_service_(),
-      work_(new boost::asio::io_service::work(work_io_service_)),
+  /// Constructor creates a thread to run a private io_context.
+  logger_service(boost::asio::io_context& io_context)
+    : boost::asio::io_context::service(io_context),
+      work_io_context_(),
+      work_(boost::asio::make_work_guard(work_io_context_)),
       work_thread_(new boost::thread(
-            boost::bind(&boost::asio::io_service::run, &work_io_service_)))
+            boost::bind(&boost::asio::io_context::run, &work_io_context_)))
   {
   }
 
-  /// Destructor shuts down the private io_service.
+  /// Destructor shuts down the private io_context.
   ~logger_service()
   {
-    /// Indicate that we have finished with the private io_service. Its
-    /// io_service::run() function will exit once all other work has completed.
+    /// Indicate that we have finished with the private io_context. Its
+    /// io_context::run() function will exit once all other work has completed.
     work_.reset();
     if (work_thread_)
       work_thread_->join();
@@ -92,7 +92,7 @@ class logger_service
   void use_file(impl_type& /*impl*/, const std::string& file)
   {
     // Pass the work of opening the file to the background thread.
-    work_io_service_.post(boost::bind(
+    boost::asio::post(work_io_context_, boost::bind(
           &logger_service::use_file_impl, this, file));
   }
 
@@ -104,13 +104,13 @@ class logger_service
     os << impl->identifier << ": " << message;
 
     // Pass the work of opening the file to the background thread.
-    work_io_service_.post(boost::bind(
+    boost::asio::post(work_io_context_, boost::bind(
           &logger_service::log_impl, this, os.str()));
   }
 
 private:
   /// Helper function used to open the output file from within the private
-  /// io_service's thread.
+  /// io_context's thread.
   void use_file_impl(const std::string& file)
   {
     ofstream_.close();
@@ -118,22 +118,23 @@ class logger_service
     ofstream_.open(file.c_str());
   }
 
-  /// Helper function used to log a message from within the private io_service's
+  /// Helper function used to log a message from within the private io_context's
   /// thread.
   void log_impl(const std::string& text)
   {
     ofstream_ << text << std::endl;
   }
 
-  /// Private io_service used for performing logging operations.
-  boost::asio::io_service work_io_service_;
+  /// Private io_context used for performing logging operations.
+  boost::asio::io_context work_io_context_;
 
-  /// Work for the private io_service to perform. If we do not give the
-  /// io_service some work to do then the io_service::run() function will exit
+  /// Work for the private io_context to perform. If we do not give the
+  /// io_context some work to do then the io_context::run() function will exit
   /// immediately.
-  boost::scoped_ptr<boost::asio::io_service::work> work_;
+  boost::asio::executor_work_guard<
+      boost::asio::io_context::executor_type> work_;
 
-  /// Thread used for running the work io_service's run loop.
+  /// Thread used for running the work io_context's run loop.
   boost::scoped_ptr<boost::thread> work_thread_;
 
   /// The file to which log messages will be written.
diff --git a/example/cpp03/services/stream_socket_service.hpp b/example/cpp03/services/stream_socket_service.hpp
deleted file mode 100644
index 4c976604e1..0000000000
--- a/example/cpp03/services/stream_socket_service.hpp
+++ /dev/null
@@ -1,351 +0,0 @@
-//
-// stream_socket_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef SERVICES_STREAM_SOCKET_SERVICE_HPP
-#define SERVICES_STREAM_SOCKET_SERVICE_HPP
-
-#include <boost/asio.hpp>
-#include <boost/noncopyable.hpp>
-#include <boost/lexical_cast.hpp>
-#include "logger.hpp"
-
-namespace services {
-
-/// Debugging stream socket service that wraps the normal stream socket service.
-template <typename Protocol>
-class stream_socket_service
-  : public boost::asio::io_service::service
-{
-private:
-  /// The type of the wrapped stream socket service.
-  typedef boost::asio::stream_socket_service<Protocol> service_impl_type;
-
-public:
-  /// The unique service identifier.
-  static boost::asio::io_service::id id;
-
-  /// The protocol type.
-  typedef Protocol protocol_type;
-
-  /// The endpoint type.
-  typedef typename Protocol::endpoint endpoint_type;
-
-  /// The implementation type of a stream socket.
-  typedef typename service_impl_type::implementation_type implementation_type;
-
-  /// The native type of a stream socket.
-  typedef typename service_impl_type::native_handle_type native_handle_type;
-
-  /// Construct a new stream socket service for the specified io_service.
-  explicit stream_socket_service(boost::asio::io_service& io_service)
-    : boost::asio::io_service::service(io_service),
-      service_impl_(boost::asio::use_service<service_impl_type>(io_service)),
-      logger_(io_service, "stream_socket")
-  {
-  }
-
-  /// Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
-  {
-  }
-
-  /// Construct a new stream socket implementation.
-  void construct(implementation_type& impl)
-  {
-    service_impl_.construct(impl);
-  }
-
-  /// Destroy a stream socket implementation.
-  void destroy(implementation_type& impl)
-  {
-    service_impl_.destroy(impl);
-  }
-
-  /// Open a new stream socket implementation.
-  boost::system::error_code open(implementation_type& impl,
-      const protocol_type& protocol, boost::system::error_code& ec)
-  {
-    logger_.log("Opening new socket");
-    return service_impl_.open(impl, protocol, ec);
-  }
-
-  /// Open a stream socket from an existing native socket.
-  boost::system::error_code assign(implementation_type& impl,
-      const protocol_type& protocol, const native_handle_type& native_socket,
-      boost::system::error_code& ec)
-  {
-    logger_.log("Assigning from a native socket");
-    return service_impl_.assign(impl, protocol, native_socket, ec);
-  }
-
-  /// Determine whether the socket is open.
-  bool is_open(const implementation_type& impl) const
-  {
-    logger_.log("Checking if socket is open");
-    return service_impl_.is_open(impl);
-  }
-
-  /// Close a stream socket implementation.
-  boost::system::error_code close(implementation_type& impl,
-      boost::system::error_code& ec)
-  {
-    logger_.log("Closing socket");
-    return service_impl_.close(impl, ec);
-  }
-
-  /// Determine whether the socket is at the out-of-band data mark.
-  bool at_mark(const implementation_type& impl,
-      boost::system::error_code& ec) const
-  {
-    logger_.log("Checking if socket is at out-of-band data mark");
-    return service_impl_.at_mark(impl, ec);
-  }
-
-  /// Determine the number of bytes available for reading.
-  std::size_t available(const implementation_type& impl,
-      boost::system::error_code& ec) const
-  {
-    logger_.log("Determining number of bytes available for reading");
-    return service_impl_.available(impl, ec);
-  }
-
-  /// Bind the stream socket to the specified local endpoint.
-  boost::system::error_code bind(implementation_type& impl,
-      const endpoint_type& endpoint, boost::system::error_code& ec)
-  {
-    logger_.log("Binding socket");
-    return service_impl_.bind(impl, endpoint, ec);
-  }
-
-  /// Connect the stream socket to the specified endpoint.
-  boost::system::error_code connect(implementation_type& impl,
-      const endpoint_type& peer_endpoint, boost::system::error_code& ec)
-  {
-    logger_.log("Connecting socket to " +
-        boost::lexical_cast<std::string>(peer_endpoint));
-    return service_impl_.connect(impl, peer_endpoint, ec);
-  }
-
-  /// Handler to wrap asynchronous connect completion.
-  template <typename Handler>
-  class connect_handler
-  {
-  public:
-    connect_handler(Handler h, logger& l)
-      : handler_(h),
-        logger_(l)
-    {
-    }
-
-    void operator()(const boost::system::error_code& e)
-    {
-      if (e)
-      {
-        std::string msg = "Asynchronous connect failed: ";
-        msg += e.message();
-        logger_.log(msg);
-      }
-      else
-      {
-        logger_.log("Asynchronous connect succeeded");
-      }
-
-      handler_(e);
-    }
-
-  private:
-    Handler handler_;
-    logger& logger_;
-  };
-
-  /// Start an asynchronous connect.
-  template <typename Handler>
-  void async_connect(implementation_type& impl,
-      const endpoint_type& peer_endpoint, Handler handler)
-  {
-    logger_.log("Starting asynchronous connect to " +
-        boost::lexical_cast<std::string>(peer_endpoint));
-    service_impl_.async_connect(impl, peer_endpoint, 
-        connect_handler<Handler>(handler, logger_));
-  }
-
-  /// Set a socket option.
-  template <typename Option>
-  boost::system::error_code set_option(implementation_type& impl,
-      const Option& option, boost::system::error_code& ec)
-  {
-    logger_.log("Setting socket option");
-    return service_impl_.set_option(impl, option, ec);
-  }
-
-  /// Get a socket option.
-  template <typename Option>
-  boost::system::error_code get_option(const implementation_type& impl,
-      Option& option, boost::system::error_code& ec) const
-  {
-    logger_.log("Getting socket option");
-    return service_impl_.get_option(impl, option, ec);
-  }
-
-  /// Perform an IO control command on the socket.
-  template <typename IO_Control_Command>
-  boost::system::error_code io_control(implementation_type& impl,
-      IO_Control_Command& command, boost::system::error_code& ec)
-  {
-    logger_.log("Performing IO control command on socket");
-    return service_impl_.io_control(impl, command, ec);
-  }
-
-  /// Get the local endpoint.
-  endpoint_type local_endpoint(const implementation_type& impl,
-      boost::system::error_code& ec) const
-  {
-    logger_.log("Getting socket's local endpoint");
-    return service_impl_.local_endpoint(impl, ec);
-  }
-
-  /// Get the remote endpoint.
-  endpoint_type remote_endpoint(const implementation_type& impl,
-      boost::system::error_code& ec) const
-  {
-    logger_.log("Getting socket's remote endpoint");
-    return service_impl_.remote_endpoint(impl, ec);
-  }
-
-  /// Disable sends or receives on the socket.
-  boost::system::error_code shutdown(implementation_type& impl,
-      boost::asio::socket_base::shutdown_type what,
-      boost::system::error_code& ec)
-  {
-    logger_.log("Shutting down socket");
-    return service_impl_.shutdown(impl, what, ec);
-  }
-
-  /// Send the given data to the peer.
-  template <typename Const_Buffers>
-  std::size_t send(implementation_type& impl, const Const_Buffers& buffers,
-      boost::asio::socket_base::message_flags flags,
-      boost::system::error_code& ec)
-  {
-    logger_.log("Sending data on socket");
-    return service_impl_.send(impl, buffers, flags, ec);
-  }
-
-  /// Handler to wrap asynchronous send completion.
-  template <typename Handler>
-  class send_handler
-  {
-  public:
-    send_handler(Handler h, logger& l)
-      : handler_(h),
-        logger_(l)
-    {
-    }
-
-    void operator()(const boost::system::error_code& e,
-        std::size_t bytes_transferred)
-    {
-      if (e)
-      {
-        std::string msg = "Asynchronous send failed: ";
-        msg += e.message();
-        logger_.log(msg);
-      }
-      else
-      {
-        logger_.log("Asynchronous send succeeded");
-      }
-
-      handler_(e, bytes_transferred);
-    }
-
-  private:
-    Handler handler_;
-    logger& logger_;
-  };
-
-  /// Start an asynchronous send.
-  template <typename Const_Buffers, typename Handler>
-  void async_send(implementation_type& impl, const Const_Buffers& buffers,
-      boost::asio::socket_base::message_flags flags, Handler handler)
-  {
-    logger_.log("Starting asynchronous send");
-    service_impl_.async_send(impl, buffers, flags,
-        send_handler<Handler>(handler, logger_));
-  }
-
-  /// Receive some data from the peer.
-  template <typename Mutable_Buffers>
-  std::size_t receive(implementation_type& impl,
-      const Mutable_Buffers& buffers,
-      boost::asio::socket_base::message_flags flags,
-      boost::system::error_code& ec)
-  {
-    logger_.log("Receiving data on socket");
-    return service_impl_.receive(impl, buffers, flags, ec);
-  }
-
-  /// Handler to wrap asynchronous receive completion.
-  template <typename Handler>
-  class receive_handler
-  {
-  public:
-    receive_handler(Handler h, logger& l)
-      : handler_(h),
-        logger_(l)
-    {
-    }
-
-    void operator()(const boost::system::error_code& e,
-        std::size_t bytes_transferred)
-    {
-      if (e)
-      {
-        std::string msg = "Asynchronous receive failed: ";
-        msg += e.message();
-        logger_.log(msg);
-      }
-      else
-      {
-        logger_.log("Asynchronous receive succeeded");
-      }
-
-      handler_(e, bytes_transferred);
-    }
-
-  private:
-    Handler handler_;
-    logger& logger_;
-  };
-
-  /// Start an asynchronous receive.
-  template <typename Mutable_Buffers, typename Handler>
-  void async_receive(implementation_type& impl, const Mutable_Buffers& buffers,
-      boost::asio::socket_base::message_flags flags, Handler handler)
-  {
-    logger_.log("Starting asynchronous receive");
-    service_impl_.async_receive(impl, buffers, flags,
-        receive_handler<Handler>(handler, logger_));
-  }
-
-private:
-  /// The wrapped stream socket service.
-  service_impl_type& service_impl_;
-
-  /// The logger used for writing debug messages.
-  mutable logger logger_;
-};
-
-template <typename Protocol>
-boost::asio::io_service::id stream_socket_service<Protocol>::id;
-
-} // namespace services
-
-#endif // SERVICES_STREAM_SOCKET_SERVICE_HPP
diff --git a/example/cpp03/socks4/sync_client.cpp b/example/cpp03/socks4/sync_client.cpp
index d331969f6c..e9106a059c 100644
--- a/example/cpp03/socks4/sync_client.cpp
+++ b/example/cpp03/socks4/sync_client.cpp
@@ -31,22 +31,21 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     // Get a list of endpoints corresponding to the SOCKS 4 server name.
-    tcp::resolver resolver(io_service);
-    tcp::resolver::query socks_query(argv[1], argv[2]);
-    tcp::resolver::iterator endpoint_iterator = resolver.resolve(socks_query);
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints = resolver.resolve(argv[1], argv[2]);
 
     // Try each endpoint until we successfully establish a connection to the
     // SOCKS 4 server.
-    tcp::socket socket(io_service);
-    boost::asio::connect(socket, endpoint_iterator);
+    tcp::socket socket(io_context);
+    boost::asio::connect(socket, endpoints);
 
     // Get an endpoint for the Boost website. This will be passed to the SOCKS
     // 4 server. Explicitly specify IPv4 since SOCKS 4 does not support IPv6.
-    tcp::resolver::query http_query(tcp::v4(), "www.boost.org", "http");
-    tcp::endpoint http_endpoint = *resolver.resolve(http_query);
+    tcp::endpoint http_endpoint =
+      *resolver.resolve(tcp::v4(), "www.boost.org", "http").begin();
 
     // Send the request to the SOCKS 4 server.
     socks4::request socks_request(
diff --git a/example/cpp03/spawn/Jamfile.v2 b/example/cpp03/spawn/Jamfile.v2
index 9a3e7218ec..19b21c5298 100644
--- a/example/cpp03/spawn/Jamfile.v2
+++ b/example/cpp03/spawn/Jamfile.v2
@@ -43,3 +43,21 @@ exe server
     <os>HPUX:<library>ipv6
     <os>HAIKU:<library>network
   ;
+
+exe parallel_grep
+  : parallel_grep.cpp
+    /boost/context//boost_context
+    /boost/coroutine//boost_coroutine
+    /boost/system//boost_system
+  : <define>BOOST_ALL_NO_LIB=1
+    <threading>multi
+    <os>SOLARIS:<library>socket
+    <os>SOLARIS:<library>nsl
+    <os>NT:<define>_WIN32_WINNT=0x0501
+    <os>NT,<toolset>gcc:<library>ws2_32
+    <os>NT,<toolset>gcc:<library>mswsock
+    <os>NT,<toolset>gcc-cygwin:<define>__USE_W32_SOCKETS
+    <os>HPUX,<toolset>gcc:<define>_XOPEN_SOURCE_EXTENDED
+    <os>HPUX:<library>ipv6
+    <os>HAIKU:<library>network
+  ;
diff --git a/example/cpp03/spawn/echo_server.cpp b/example/cpp03/spawn/echo_server.cpp
index aa718c441b..db6a1679f5 100644
--- a/example/cpp03/spawn/echo_server.cpp
+++ b/example/cpp03/spawn/echo_server.cpp
@@ -9,7 +9,7 @@
 //
 
 #include <boost/asio/deadline_timer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/spawn.hpp>
 #include <boost/asio/write.hpp>
@@ -23,10 +23,10 @@ using boost::asio::ip::tcp;
 class session : public boost::enable_shared_from_this<session>
 {
 public:
-  explicit session(boost::asio::io_service& io_service)
-    : strand_(io_service),
-      socket_(io_service),
-      timer_(io_service)
+  explicit session(boost::asio::io_context& io_context)
+    : strand_(io_context),
+      socket_(io_context),
+      timer_(io_context)
   {
   }
 
@@ -76,20 +76,20 @@ class session : public boost::enable_shared_from_this<session>
     }
   }
 
-  boost::asio::io_service::strand strand_;
+  boost::asio::io_context::strand strand_;
   tcp::socket socket_;
   boost::asio::deadline_timer timer_;
 };
 
-void do_accept(boost::asio::io_service& io_service,
+void do_accept(boost::asio::io_context& io_context,
     unsigned short port, boost::asio::yield_context yield)
 {
-  tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), port));
+  tcp::acceptor acceptor(io_context, tcp::endpoint(tcp::v4(), port));
 
   for (;;)
   {
     boost::system::error_code ec;
-    boost::shared_ptr<session> new_session(new session(io_service));
+    boost::shared_ptr<session> new_session(new session(io_context));
     acceptor.async_accept(new_session->socket(), yield[ec]);
     if (!ec) new_session->go();
   }
@@ -105,13 +105,13 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    boost::asio::spawn(io_service,
+    boost::asio::spawn(io_context,
         boost::bind(do_accept,
-          boost::ref(io_service), atoi(argv[1]), _1));
+          boost::ref(io_context), atoi(argv[1]), _1));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/spawn/parallel_grep.cpp b/example/cpp03/spawn/parallel_grep.cpp
new file mode 100644
index 0000000000..63aa2fc447
--- /dev/null
+++ b/example/cpp03/spawn/parallel_grep.cpp
@@ -0,0 +1,90 @@
+//
+// parallel_grep.cpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio/dispatch.hpp>
+#include <boost/asio/post.hpp>
+#include <boost/asio/spawn.hpp>
+#include <boost/asio/strand.hpp>
+#include <boost/asio/thread_pool.hpp>
+#include <boost/thread/thread.hpp>
+#include <boost/bind.hpp>
+#include <fstream>
+#include <iostream>
+#include <string>
+
+using boost::asio::dispatch;
+using boost::asio::spawn;
+using boost::asio::strand;
+using boost::asio::thread_pool;
+using boost::asio::yield_context;
+
+void print_match(std::string input_file, std::string line)
+{
+  std::cout << input_file << ':' << line << std::endl;
+}
+
+void search_file(std::string search_string, std::string input_file,
+    strand<thread_pool::executor_type> output_strand, yield_context yield)
+{
+  std::ifstream is(input_file.c_str());
+  std::string line;
+  std::size_t line_num = 0;
+  while (std::getline(is, line))
+  {
+    // If we find a match, send a message to the output.
+    if (line.find(search_string) != std::string::npos)
+    {
+      dispatch(output_strand, boost::bind(&print_match, input_file, line));
+    }
+
+    // Every so often we yield control to another coroutine.
+    if (++line_num % 10 == 0)
+      post(yield);
+  }
+}
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc < 2)
+    {
+      std::cerr << "Usage: parallel_grep <string> <files...>\n";
+      return 1;
+    }
+
+    // We use a fixed size pool of threads for reading the input files. The
+    // number of threads is automatically determined based on the number of
+    // CPUs available in the system.
+    thread_pool pool;
+
+    // To prevent the output from being garbled, we use a strand to synchronise
+    // printing.
+    strand<thread_pool::executor_type> output_strand(pool.get_executor());
+
+    // Spawn a new coroutine for each file specified on the command line.
+    std::string search_string = argv[1];
+    for (int argn = 2; argn < argc; ++argn)
+    {
+      std::string input_file = argv[argn];
+      spawn(pool, boost::bind(&search_file,
+            search_string, input_file, output_strand, _1));
+    }
+
+    // Join the thread pool to wait for all the spawned tasks to complete.
+    pool.join();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}
diff --git a/example/cpp03/ssl/client.cpp b/example/cpp03/ssl/client.cpp
index 8a86865550..7239496add 100644
--- a/example/cpp03/ssl/client.cpp
+++ b/example/cpp03/ssl/client.cpp
@@ -19,16 +19,16 @@ enum { max_length = 1024 };
 class client
 {
 public:
-  client(boost::asio::io_service& io_service,
+  client(boost::asio::io_context& io_context,
       boost::asio::ssl::context& context,
-      boost::asio::ip::tcp::resolver::iterator endpoint_iterator)
-    : socket_(io_service, context)
+      boost::asio::ip::tcp::resolver::results_type endpoints)
+    : socket_(io_context, context)
   {
     socket_.set_verify_mode(boost::asio::ssl::verify_peer);
     socket_.set_verify_callback(
         boost::bind(&client::verify_certificate, this, _1, _2));
 
-    boost::asio::async_connect(socket_.lowest_layer(), endpoint_iterator,
+    boost::asio::async_connect(socket_.lowest_layer(), endpoints,
         boost::bind(&client::handle_connect, this,
           boost::asio::placeholders::error));
   }
@@ -134,18 +134,18 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    boost::asio::ip::tcp::resolver resolver(io_service);
-    boost::asio::ip::tcp::resolver::query query(argv[1], argv[2]);
-    boost::asio::ip::tcp::resolver::iterator iterator = resolver.resolve(query);
+    boost::asio::ip::tcp::resolver resolver(io_context);
+    boost::asio::ip::tcp::resolver::results_type endpoints =
+      resolver.resolve(argv[1], argv[2]);
 
     boost::asio::ssl::context ctx(boost::asio::ssl::context::sslv23);
     ctx.load_verify_file("ca.pem");
 
-    client c(io_service, ctx, iterator);
+    client c(io_context, ctx, endpoints);
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/ssl/server.cpp b/example/cpp03/ssl/server.cpp
index 772b178435..604189034e 100644
--- a/example/cpp03/ssl/server.cpp
+++ b/example/cpp03/ssl/server.cpp
@@ -19,9 +19,9 @@ typedef boost::asio::ssl::stream<boost::asio::ip::tcp::socket> ssl_socket;
 class session
 {
 public:
-  session(boost::asio::io_service& io_service,
+  session(boost::asio::io_context& io_context,
       boost::asio::ssl::context& context)
-    : socket_(io_service, context)
+    : socket_(io_context, context)
   {
   }
 
@@ -92,9 +92,9 @@ class session
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, unsigned short port)
-    : io_service_(io_service),
-      acceptor_(io_service,
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : io_context_(io_context),
+      acceptor_(io_context,
           boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), port)),
       context_(boost::asio::ssl::context::sslv23)
   {
@@ -117,7 +117,7 @@ class server
 
   void start_accept()
   {
-    session* new_session = new session(io_service_, context_);
+    session* new_session = new session(io_context_, context_);
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session,
           boost::asio::placeholders::error));
@@ -139,7 +139,7 @@ class server
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   boost::asio::ip::tcp::acceptor acceptor_;
   boost::asio::ssl::context context_;
 };
@@ -154,12 +154,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]));
+    server s(io_context, atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/timeouts/async_tcp_client.cpp b/example/cpp03/timeouts/async_tcp_client.cpp
index 9d52300ab3..2134e6395d 100644
--- a/example/cpp03/timeouts/async_tcp_client.cpp
+++ b/example/cpp03/timeouts/async_tcp_client.cpp
@@ -9,7 +9,7 @@
 //
 
 #include <boost/asio/deadline_timer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/read_until.hpp>
 #include <boost/asio/streambuf.hpp>
@@ -83,20 +83,21 @@ using boost::asio::ip::tcp;
 class client
 {
 public:
-  client(boost::asio::io_service& io_service)
+  client(boost::asio::io_context& io_context)
     : stopped_(false),
-      socket_(io_service),
-      deadline_(io_service),
-      heartbeat_timer_(io_service)
+      socket_(io_context),
+      deadline_(io_context),
+      heartbeat_timer_(io_context)
   {
   }
 
   // Called by the user of the client class to initiate the connection process.
-  // The endpoint iterator will have been obtained using a tcp::resolver.
-  void start(tcp::resolver::iterator endpoint_iter)
+  // The endpoints will have been obtained using a tcp::resolver.
+  void start(tcp::resolver::results_type endpoints)
   {
     // Start the connect actor.
-    start_connect(endpoint_iter);
+    endpoints_ = endpoints;
+    start_connect(endpoints_.begin());
 
     // Start the deadline actor. You will note that we're not setting any
     // particular deadline here. Instead, the connect and input actors will
@@ -117,9 +118,9 @@ class client
   }
 
 private:
-  void start_connect(tcp::resolver::iterator endpoint_iter)
+  void start_connect(tcp::resolver::results_type::iterator endpoint_iter)
   {
-    if (endpoint_iter != tcp::resolver::iterator())
+    if (endpoint_iter != endpoints_.end())
     {
       std::cout << "Trying " << endpoint_iter->endpoint() << "...\n";
 
@@ -139,7 +140,7 @@ class client
   }
 
   void handle_connect(const boost::system::error_code& ec,
-      tcp::resolver::iterator endpoint_iter)
+      tcp::resolver::results_type::iterator endpoint_iter)
   {
     if (stopped_)
       return;
@@ -273,6 +274,7 @@ class client
 
 private:
   bool stopped_;
+  tcp::resolver::results_type endpoints_;
   tcp::socket socket_;
   boost::asio::streambuf input_buffer_;
   deadline_timer deadline_;
@@ -289,13 +291,13 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
-    tcp::resolver r(io_service);
-    client c(io_service);
+    boost::asio::io_context io_context;
+    tcp::resolver r(io_context);
+    client c(io_context);
 
-    c.start(r.resolve(tcp::resolver::query(argv[1], argv[2])));
+    c.start(r.resolve(argv[1], argv[2]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/timeouts/blocking_tcp_client.cpp b/example/cpp03/timeouts/blocking_tcp_client.cpp
index 765a2a7a71..67224cfd0f 100644
--- a/example/cpp03/timeouts/blocking_tcp_client.cpp
+++ b/example/cpp03/timeouts/blocking_tcp_client.cpp
@@ -10,7 +10,7 @@
 
 #include <boost/asio/connect.hpp>
 #include <boost/asio/deadline_timer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/read_until.hpp>
 #include <boost/asio/streambuf.hpp>
@@ -48,14 +48,14 @@ using boost::lambda::_1;
 // and any outstanding operations are consequently cancelled. The socket
 // operations themselves use boost::lambda function objects as completion
 // handlers. For a given socket operation, the client object runs the
-// io_service to block thread execution until the actor completes.
+// io_context to block thread execution until the actor completes.
 //
 class client
 {
 public:
   client()
-    : socket_(io_service_),
-      deadline_(io_service_)
+    : socket_(io_context_),
+      deadline_(io_context_)
   {
     // No deadline is required until the first socket operation is started. We
     // set the deadline to positive infinity so that the actor takes no action
@@ -70,8 +70,8 @@ class client
       boost::posix_time::time_duration timeout)
   {
     // Resolve the host name and service to a list of endpoints.
-    tcp::resolver::query query(host, service);
-    tcp::resolver::iterator iter = tcp::resolver(io_service_).resolve(query);
+    tcp::resolver::results_type endpoints =
+      tcp::resolver(io_context_).resolve(host, service);
 
     // Set a deadline for the asynchronous operation. As a host name may
     // resolve to multiple endpoints, this function uses the composed operation
@@ -90,10 +90,10 @@ class client
     // object is used as a callback and will update the ec variable when the
     // operation completes. The blocking_udp_client.cpp example shows how you
     // can use boost::bind rather than boost::lambda.
-    boost::asio::async_connect(socket_, iter, var(ec) = _1);
+    boost::asio::async_connect(socket_, endpoints, var(ec) = _1);
 
     // Block until the asynchronous operation has completed.
-    do io_service_.run_one(); while (ec == boost::asio::error::would_block);
+    do io_context_.run_one(); while (ec == boost::asio::error::would_block);
 
     // Determine whether a connection was successfully established. The
     // deadline actor may have had a chance to run and close our socket, even
@@ -126,7 +126,7 @@ class client
     boost::asio::async_read_until(socket_, input_buffer_, '\n', var(ec) = _1);
 
     // Block until the asynchronous operation has completed.
-    do io_service_.run_one(); while (ec == boost::asio::error::would_block);
+    do io_context_.run_one(); while (ec == boost::asio::error::would_block);
 
     if (ec)
       throw boost::system::system_error(ec);
@@ -161,7 +161,7 @@ class client
     boost::asio::async_write(socket_, boost::asio::buffer(data), var(ec) = _1);
 
     // Block until the asynchronous operation has completed.
-    do io_service_.run_one(); while (ec == boost::asio::error::would_block);
+    do io_context_.run_one(); while (ec == boost::asio::error::would_block);
 
     if (ec)
       throw boost::system::system_error(ec);
@@ -190,7 +190,7 @@ class client
     deadline_.async_wait(bind(&client::check_deadline, this));
   }
 
-  boost::asio::io_service io_service_;
+  boost::asio::io_context io_context_;
   tcp::socket socket_;
   deadline_timer deadline_;
   boost::asio::streambuf input_buffer_;
diff --git a/example/cpp03/timeouts/blocking_udp_client.cpp b/example/cpp03/timeouts/blocking_udp_client.cpp
index fd81522cc9..03aafca2f7 100644
--- a/example/cpp03/timeouts/blocking_udp_client.cpp
+++ b/example/cpp03/timeouts/blocking_udp_client.cpp
@@ -9,7 +9,7 @@
 //
 
 #include <boost/asio/deadline_timer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include <cstdlib>
 #include <boost/bind.hpp>
@@ -51,15 +51,15 @@ using boost::asio::ip::udp;
 //                |                |
 //                +----------------+
 //
-// The client object runs the io_service to block thread execution until the
+// The client object runs the io_context to block thread execution until the
 // actor completes.
 //
 class client
 {
 public:
   client(const udp::endpoint& listen_endpoint)
-    : socket_(io_service_, listen_endpoint),
-      deadline_(io_service_)
+    : socket_(io_context_, listen_endpoint),
+      deadline_(io_context_)
   {
     // No deadline is required until the first socket operation is started. We
     // set the deadline to positive infinity so that the actor takes no action
@@ -90,7 +90,7 @@ class client
         boost::bind(&client::handle_receive, _1, _2, &ec, &length));
 
     // Block until the asynchronous operation has completed.
-    do io_service_.run_one(); while (ec == boost::asio::error::would_block);
+    do io_context_.run_one(); while (ec == boost::asio::error::would_block);
 
     return length;
   }
@@ -129,7 +129,7 @@ class client
   }
 
 private:
-  boost::asio::io_service io_service_;
+  boost::asio::io_context io_context_;
   udp::socket socket_;
   deadline_timer deadline_;
 };
@@ -149,7 +149,7 @@ int main(int argc, char* argv[])
     }
 
     udp::endpoint listen_endpoint(
-        boost::asio::ip::address::from_string(argv[1]),
+        boost::asio::ip::make_address(argv[1]),
         std::atoi(argv[2]));
 
     client c(listen_endpoint);
diff --git a/example/cpp03/timeouts/server.cpp b/example/cpp03/timeouts/server.cpp
index ce4dce60a8..23c276521e 100644
--- a/example/cpp03/timeouts/server.cpp
+++ b/example/cpp03/timeouts/server.cpp
@@ -17,7 +17,7 @@
 #include <boost/shared_ptr.hpp>
 #include <boost/enable_shared_from_this.hpp>
 #include <boost/asio/deadline_timer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include <boost/asio/read_until.hpp>
@@ -133,12 +133,12 @@ class tcp_session
     public boost::enable_shared_from_this<tcp_session>
 {
 public:
-  tcp_session(boost::asio::io_service& io_service, channel& ch)
+  tcp_session(boost::asio::io_context& io_context, channel& ch)
     : channel_(ch),
-      socket_(io_service),
-      input_deadline_(io_service),
-      non_empty_output_queue_(io_service),
-      output_deadline_(io_service)
+      socket_(io_context),
+      input_deadline_(io_context),
+      non_empty_output_queue_(io_context),
+      output_deadline_(io_context)
   {
     input_deadline_.expires_at(boost::posix_time::pos_infin);
     output_deadline_.expires_at(boost::posix_time::pos_infin);
@@ -334,9 +334,9 @@ class udp_broadcaster
   : public subscriber
 {
 public:
-  udp_broadcaster(boost::asio::io_service& io_service,
+  udp_broadcaster(boost::asio::io_context& io_context,
       const udp::endpoint& broadcast_endpoint)
-    : socket_(io_service)
+    : socket_(io_context)
   {
     socket_.connect(broadcast_endpoint);
   }
@@ -356,13 +356,13 @@ class udp_broadcaster
 class server
 {
 public:
-  server(boost::asio::io_service& io_service,
+  server(boost::asio::io_context& io_context,
       const tcp::endpoint& listen_endpoint,
       const udp::endpoint& broadcast_endpoint)
-    : io_service_(io_service),
-      acceptor_(io_service, listen_endpoint)
+    : io_context_(io_context),
+      acceptor_(io_context, listen_endpoint)
   {
-    subscriber_ptr bc(new udp_broadcaster(io_service_, broadcast_endpoint));
+    subscriber_ptr bc(new udp_broadcaster(io_context_, broadcast_endpoint));
     channel_.join(bc);
 
     start_accept();
@@ -370,7 +370,7 @@ class server
 
   void start_accept()
   {
-    tcp_session_ptr new_session(new tcp_session(io_service_, channel_));
+    tcp_session_ptr new_session(new tcp_session(io_context_, channel_));
 
     acceptor_.async_accept(new_session->socket(),
         boost::bind(&server::handle_accept, this, new_session, _1));
@@ -388,7 +388,7 @@ class server
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   tcp::acceptor acceptor_;
   channel channel_;
 };
@@ -407,16 +407,16 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     tcp::endpoint listen_endpoint(tcp::v4(), atoi(argv[1]));
 
     udp::endpoint broadcast_endpoint(
-        boost::asio::ip::address::from_string(argv[2]), atoi(argv[3]));
+        boost::asio::ip::make_address(argv[2]), atoi(argv[3]));
 
-    server s(io_service, listen_endpoint, broadcast_endpoint);
+    server s(io_context, listen_endpoint, broadcast_endpoint);
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/timers/tick_count_timer.cpp b/example/cpp03/timers/tick_count_timer.cpp
index 4f0c85d054..8111a5cacd 100644
--- a/example/cpp03/timers/tick_count_timer.cpp
+++ b/example/cpp03/timers/tick_count_timer.cpp
@@ -101,9 +101,9 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tick_count_timer timer(io_service, 5000);
+    tick_count_timer timer(io_context, 5000);
     std::cout << "Starting synchronous wait\n";
     timer.wait();
     std::cout << "Finished synchronous wait\n";
@@ -111,7 +111,7 @@ int main()
     timer.expires_from_now(5000);
     std::cout << "Starting asynchronous wait\n";
     timer.async_wait(&handle_timeout);
-    io_service.run();
+    io_context.run();
     std::cout << "Finished asynchronous wait\n";
   }
   catch (std::exception& e)
diff --git a/example/cpp03/timers/time_t_timer.cpp b/example/cpp03/timers/time_t_timer.cpp
index 19e84e35a4..95b443eccd 100644
--- a/example/cpp03/timers/time_t_timer.cpp
+++ b/example/cpp03/timers/time_t_timer.cpp
@@ -69,9 +69,9 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    time_t_timer timer(io_service);
+    time_t_timer timer(io_context);
 
     timer.expires_from_now(5);
     std::cout << "Starting synchronous wait\n";
@@ -81,7 +81,7 @@ int main()
     timer.expires_from_now(5);
     std::cout << "Starting asynchronous wait\n";
     timer.async_wait(&handle_timeout);
-    io_service.run();
+    io_context.run();
     std::cout << "Finished asynchronous wait\n";
   }
   catch (std::exception& e)
diff --git a/example/cpp03/tutorial/daytime1/client.cpp b/example/cpp03/tutorial/daytime1/client.cpp
index 2e00a5a773..d311365df7 100644
--- a/example/cpp03/tutorial/daytime1/client.cpp
+++ b/example/cpp03/tutorial/daytime1/client.cpp
@@ -24,14 +24,14 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tcp::resolver resolver(io_service);
-    tcp::resolver::query query(argv[1], "daytime");
-    tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints =
+      resolver.resolve(argv[1], "daytime");
 
-    tcp::socket socket(io_service);
-    boost::asio::connect(socket, endpoint_iterator);
+    tcp::socket socket(io_context);
+    boost::asio::connect(socket, endpoints);
 
     for (;;)
     {
diff --git a/example/cpp03/tutorial/daytime2/server.cpp b/example/cpp03/tutorial/daytime2/server.cpp
index 1e70b684b5..d6fa140f23 100644
--- a/example/cpp03/tutorial/daytime2/server.cpp
+++ b/example/cpp03/tutorial/daytime2/server.cpp
@@ -26,13 +26,13 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), 13));
+    tcp::acceptor acceptor(io_context, tcp::endpoint(tcp::v4(), 13));
 
     for (;;)
     {
-      tcp::socket socket(io_service);
+      tcp::socket socket(io_context);
       acceptor.accept(socket);
 
       std::string message = make_daytime_string();
diff --git a/example/cpp03/tutorial/daytime3/server.cpp b/example/cpp03/tutorial/daytime3/server.cpp
index ede7d9d024..196ba6ab2f 100644
--- a/example/cpp03/tutorial/daytime3/server.cpp
+++ b/example/cpp03/tutorial/daytime3/server.cpp
@@ -31,9 +31,9 @@ class tcp_connection
 public:
   typedef boost::shared_ptr<tcp_connection> pointer;
 
-  static pointer create(boost::asio::io_service& io_service)
+  static pointer create(boost::asio::io_context& io_context)
   {
-    return pointer(new tcp_connection(io_service));
+    return pointer(new tcp_connection(io_context));
   }
 
   tcp::socket& socket()
@@ -52,8 +52,8 @@ class tcp_connection
   }
 
 private:
-  tcp_connection(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  tcp_connection(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -69,8 +69,8 @@ class tcp_connection
 class tcp_server
 {
 public:
-  tcp_server(boost::asio::io_service& io_service)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), 13))
+  tcp_server(boost::asio::io_context& io_context)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), 13))
   {
     start_accept();
   }
@@ -79,7 +79,7 @@ class tcp_server
   void start_accept()
   {
     tcp_connection::pointer new_connection =
-      tcp_connection::create(acceptor_.get_io_service());
+      tcp_connection::create(acceptor_.get_executor().context());
 
     acceptor_.async_accept(new_connection->socket(),
         boost::bind(&tcp_server::handle_accept, this, new_connection,
@@ -104,9 +104,9 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
-    tcp_server server(io_service);
-    io_service.run();
+    boost::asio::io_context io_context;
+    tcp_server server(io_context);
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/tutorial/daytime4/client.cpp b/example/cpp03/tutorial/daytime4/client.cpp
index a6a001db43..1432ff1eea 100644
--- a/example/cpp03/tutorial/daytime4/client.cpp
+++ b/example/cpp03/tutorial/daytime4/client.cpp
@@ -24,13 +24,13 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    udp::resolver resolver(io_service);
-    udp::resolver::query query(udp::v4(), argv[1], "daytime");
-    udp::endpoint receiver_endpoint = *resolver.resolve(query);
+    udp::resolver resolver(io_context);
+    udp::endpoint receiver_endpoint =
+      *resolver.resolve(udp::v4(), argv[1], "daytime").begin();
 
-    udp::socket socket(io_service);
+    udp::socket socket(io_context);
     socket.open(udp::v4());
 
     boost::array<char, 1> send_buf  = {{ 0 }};
diff --git a/example/cpp03/tutorial/daytime5/server.cpp b/example/cpp03/tutorial/daytime5/server.cpp
index 8890a36e28..7299587879 100644
--- a/example/cpp03/tutorial/daytime5/server.cpp
+++ b/example/cpp03/tutorial/daytime5/server.cpp
@@ -27,9 +27,9 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    udp::socket socket(io_service, udp::endpoint(udp::v4(), 13));
+    udp::socket socket(io_context, udp::endpoint(udp::v4(), 13));
 
     for (;;)
     {
diff --git a/example/cpp03/tutorial/daytime6/server.cpp b/example/cpp03/tutorial/daytime6/server.cpp
index dad2cb01af..09f9c0505c 100644
--- a/example/cpp03/tutorial/daytime6/server.cpp
+++ b/example/cpp03/tutorial/daytime6/server.cpp
@@ -28,8 +28,8 @@ std::string make_daytime_string()
 class udp_server
 {
 public:
-  udp_server(boost::asio::io_service& io_service)
-    : socket_(io_service, udp::endpoint(udp::v4(), 13))
+  udp_server(boost::asio::io_context& io_context)
+    : socket_(io_context, udp::endpoint(udp::v4(), 13))
   {
     start_receive();
   }
@@ -76,9 +76,9 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
-    udp_server server(io_service);
-    io_service.run();
+    boost::asio::io_context io_context;
+    udp_server server(io_context);
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/tutorial/daytime7/server.cpp b/example/cpp03/tutorial/daytime7/server.cpp
index b8a0273a78..c83e74e4ad 100644
--- a/example/cpp03/tutorial/daytime7/server.cpp
+++ b/example/cpp03/tutorial/daytime7/server.cpp
@@ -33,9 +33,9 @@ class tcp_connection
 public:
   typedef boost::shared_ptr<tcp_connection> pointer;
 
-  static pointer create(boost::asio::io_service& io_service)
+  static pointer create(boost::asio::io_context& io_context)
   {
-    return pointer(new tcp_connection(io_service));
+    return pointer(new tcp_connection(io_context));
   }
 
   tcp::socket& socket()
@@ -52,8 +52,8 @@ class tcp_connection
   }
 
 private:
-  tcp_connection(boost::asio::io_service& io_service)
-    : socket_(io_service)
+  tcp_connection(boost::asio::io_context& io_context)
+    : socket_(io_context)
   {
   }
 
@@ -68,8 +68,8 @@ class tcp_connection
 class tcp_server
 {
 public:
-  tcp_server(boost::asio::io_service& io_service)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), 13))
+  tcp_server(boost::asio::io_context& io_context)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), 13))
   {
     start_accept();
   }
@@ -78,7 +78,7 @@ class tcp_server
   void start_accept()
   {
     tcp_connection::pointer new_connection =
-      tcp_connection::create(acceptor_.get_io_service());
+      tcp_connection::create(acceptor_.get_executor().context());
 
     acceptor_.async_accept(new_connection->socket(),
         boost::bind(&tcp_server::handle_accept, this, new_connection,
@@ -102,8 +102,8 @@ class tcp_server
 class udp_server
 {
 public:
-  udp_server(boost::asio::io_service& io_service)
-    : socket_(io_service, udp::endpoint(udp::v4(), 13))
+  udp_server(boost::asio::io_context& io_context)
+    : socket_(io_context, udp::endpoint(udp::v4(), 13))
   {
     start_receive();
   }
@@ -144,10 +144,10 @@ int main()
 {
   try
   {
-    boost::asio::io_service io_service;
-    tcp_server server1(io_service);
-    udp_server server2(io_service);
-    io_service.run();
+    boost::asio::io_context io_context;
+    tcp_server server1(io_context);
+    udp_server server2(io_context);
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp03/tutorial/timer1/timer.cpp b/example/cpp03/tutorial/timer1/timer.cpp
index 982db427d2..a2ef07a989 100644
--- a/example/cpp03/tutorial/timer1/timer.cpp
+++ b/example/cpp03/tutorial/timer1/timer.cpp
@@ -14,7 +14,7 @@
 
 int main()
 {
-  boost::asio::io_service io;
+  boost::asio::io_context io;
 
   boost::asio::deadline_timer t(io, boost::posix_time::seconds(5));
   t.wait();
diff --git a/example/cpp03/tutorial/timer2/timer.cpp b/example/cpp03/tutorial/timer2/timer.cpp
index f88b774981..6a595975a3 100644
--- a/example/cpp03/tutorial/timer2/timer.cpp
+++ b/example/cpp03/tutorial/timer2/timer.cpp
@@ -19,7 +19,7 @@ void print(const boost::system::error_code& /*e*/)
 
 int main()
 {
-  boost::asio::io_service io;
+  boost::asio::io_context io;
 
   boost::asio::deadline_timer t(io, boost::posix_time::seconds(5));
   t.async_wait(&print);
diff --git a/example/cpp03/tutorial/timer3/timer.cpp b/example/cpp03/tutorial/timer3/timer.cpp
index 813f377a30..ab957c474f 100644
--- a/example/cpp03/tutorial/timer3/timer.cpp
+++ b/example/cpp03/tutorial/timer3/timer.cpp
@@ -29,7 +29,7 @@ void print(const boost::system::error_code& /*e*/,
 
 int main()
 {
-  boost::asio::io_service io;
+  boost::asio::io_context io;
 
   int count = 0;
   boost::asio::deadline_timer t(io, boost::posix_time::seconds(1));
diff --git a/example/cpp03/tutorial/timer4/timer.cpp b/example/cpp03/tutorial/timer4/timer.cpp
index 41d0d922e4..7af2cc869a 100644
--- a/example/cpp03/tutorial/timer4/timer.cpp
+++ b/example/cpp03/tutorial/timer4/timer.cpp
@@ -16,7 +16,7 @@
 class printer
 {
 public:
-  printer(boost::asio::io_service& io)
+  printer(boost::asio::io_context& io)
     : timer_(io, boost::posix_time::seconds(1)),
       count_(0)
   {
@@ -47,7 +47,7 @@ class printer
 
 int main()
 {
-  boost::asio::io_service io;
+  boost::asio::io_context io;
   printer p(io);
   io.run();
 
diff --git a/example/cpp03/tutorial/timer5/timer.cpp b/example/cpp03/tutorial/timer5/timer.cpp
index 0e5752948e..9695670b55 100644
--- a/example/cpp03/tutorial/timer5/timer.cpp
+++ b/example/cpp03/tutorial/timer5/timer.cpp
@@ -17,14 +17,17 @@
 class printer
 {
 public:
-  printer(boost::asio::io_service& io)
+  printer(boost::asio::io_context& io)
     : strand_(io),
       timer1_(io, boost::posix_time::seconds(1)),
       timer2_(io, boost::posix_time::seconds(1)),
       count_(0)
   {
-    timer1_.async_wait(strand_.wrap(boost::bind(&printer::print1, this)));
-    timer2_.async_wait(strand_.wrap(boost::bind(&printer::print2, this)));
+    timer1_.async_wait(boost::asio::bind_executor(strand_,
+          boost::bind(&printer::print1, this)));
+
+    timer2_.async_wait(boost::asio::bind_executor(strand_,
+          boost::bind(&printer::print2, this)));
   }
 
   ~printer()
@@ -40,7 +43,9 @@ class printer
       ++count_;
 
       timer1_.expires_at(timer1_.expires_at() + boost::posix_time::seconds(1));
-      timer1_.async_wait(strand_.wrap(boost::bind(&printer::print1, this)));
+
+      timer1_.async_wait(boost::asio::bind_executor(strand_,
+            boost::bind(&printer::print1, this)));
     }
   }
 
@@ -52,12 +57,14 @@ class printer
       ++count_;
 
       timer2_.expires_at(timer2_.expires_at() + boost::posix_time::seconds(1));
-      timer2_.async_wait(strand_.wrap(boost::bind(&printer::print2, this)));
+
+      timer2_.async_wait(boost::asio::bind_executor(strand_,
+            boost::bind(&printer::print2, this)));
     }
   }
 
 private:
-  boost::asio::io_service::strand strand_;
+  boost::asio::io_context::strand strand_;
   boost::asio::deadline_timer timer1_;
   boost::asio::deadline_timer timer2_;
   int count_;
@@ -65,9 +72,9 @@ class printer
 
 int main()
 {
-  boost::asio::io_service io;
+  boost::asio::io_context io;
   printer p(io);
-  boost::thread t(boost::bind(&boost::asio::io_service::run, &io));
+  boost::thread t(boost::bind(&boost::asio::io_context::run, &io));
   io.run();
   t.join();
 
diff --git a/example/cpp03/tutorial/timer_dox.txt b/example/cpp03/tutorial/timer_dox.txt
index 83a3285232..32e29982e5 100644
--- a/example/cpp03/tutorial/timer_dox.txt
+++ b/example/cpp03/tutorial/timer_dox.txt
@@ -292,8 +292,8 @@ Return to \ref tuttimer4
 /**
 \page tuttimer5 Timer.5 - Synchronising handlers in multithreaded programs
 
-This tutorial demonstrates the use of the boost::asio::strand class to synchronise
-callback handlers in a multithreaded program.
+This tutorial demonstrates the use of the boost::asio::io_service::strand class to
+synchronise callback handlers in a multithreaded program.
 
 The previous four tutorials avoided the issue of handler synchronisation by
 calling the boost::asio::io_service::run() function from one thread only. As you
@@ -329,22 +329,25 @@ tutorial by running two timers in parallel.
 
 In addition to initialising a pair of boost::asio::deadline_timer members, the
 constructor initialises the <tt>strand_</tt> member, an object of type
-boost::asio::strand.
+boost::asio::io_service::strand.
 
-An boost::asio::strand guarantees that, for those handlers that are dispatched through
-it, an executing handler will be allowed to complete before the next one is
-started. This is guaranteed irrespective of the number of threads that are
-calling boost::asio::io_service::run(). Of course, the handlers may still execute
-concurrently with other handlers that were <b>not</b> dispatched through an
-boost::asio::strand, or were dispatched through a different boost::asio::strand object.
+An boost::asio::io_service::strand is an executor that guarantees that, for those
+handlers that are dispatched through it, an executing handler will be allowed
+to complete before the next one is started. This is guaranteed irrespective of
+the number of threads that are calling boost::asio::io_service::run(). Of course, the
+handlers may still execute concurrently with other handlers that were
+<b>not</b> dispatched through an boost::asio::io_service::strand, or were dispatched
+through a different boost::asio::io_service::strand object.
 
 \until {
 
-When initiating the asynchronous operations, each callback handler is "wrapped"
-using the boost::asio::strand object. The boost::asio::strand::wrap() function returns a new
-handler that automatically dispatches its contained handler through the
-boost::asio::strand object. By wrapping the handlers using the same boost::asio::strand, we
-are ensuring that they cannot execute concurrently.
+When initiating the asynchronous operations, each callback handler is "bound"
+to an boost::asio::io_service::strand object. The
+boost::asio::io_service::strand::bind_executor() function returns a new handler that
+automatically dispatches its contained handler through the
+boost::asio::io_service::strand object. By binding the handlers to the same
+boost::asio::io_service::strand, we are ensuring that they cannot execute
+concurrently.
 
 \until }
 \until }
diff --git a/example/cpp03/windows/transmit_file.cpp b/example/cpp03/windows/transmit_file.cpp
index 2be12c6992..38ff8a9d60 100644
--- a/example/cpp03/windows/transmit_file.cpp
+++ b/example/cpp03/windows/transmit_file.cpp
@@ -28,7 +28,7 @@ void transmit_file(tcp::socket& socket,
     random_access_handle& file, Handler handler)
 {
   // Construct an OVERLAPPED-derived object to contain the handler.
-  overlapped_ptr overlapped(socket.get_io_service(), handler);
+  overlapped_ptr overlapped(socket.get_executor().context(), handler);
 
   // Initiate the TransmitFile operation.
   BOOL ok = ::TransmitFile(socket.native_handle(),
@@ -40,7 +40,7 @@ void transmit_file(tcp::socket& socket,
   {
     // The operation completed immediately, so a completion notification needs
     // to be posted. When complete() is called, ownership of the OVERLAPPED-
-    // derived object passes to the io_service.
+    // derived object passes to the io_context.
     boost::system::error_code ec(last_error,
         boost::asio::error::get_system_category());
     overlapped.complete(ec, 0);
@@ -48,7 +48,7 @@ void transmit_file(tcp::socket& socket,
   else
   {
     // The operation was successfully initiated, so ownership of the
-    // OVERLAPPED-derived object has passed to the io_service.
+    // OVERLAPPED-derived object has passed to the io_context.
     overlapped.release();
   }
 }
@@ -59,10 +59,10 @@ class connection
 public:
   typedef boost::shared_ptr<connection> pointer;
 
-  static pointer create(boost::asio::io_service& io_service,
+  static pointer create(boost::asio::io_context& io_context,
       const std::string& filename)
   {
-    return pointer(new connection(io_service, filename));
+    return pointer(new connection(io_context, filename));
   }
 
   tcp::socket& socket()
@@ -85,10 +85,10 @@ class connection
   }
 
 private:
-  connection(boost::asio::io_service& io_service, const std::string& filename)
-    : socket_(io_service),
+  connection(boost::asio::io_context& io_context, const std::string& filename)
+    : socket_(io_context),
       filename_(filename),
-      file_(io_service)
+      file_(io_context)
   {
   }
 
@@ -107,9 +107,9 @@ class connection
 class server
 {
 public:
-  server(boost::asio::io_service& io_service,
+  server(boost::asio::io_context& io_context,
       unsigned short port, const std::string& filename)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port)),
       filename_(filename)
   {
     start_accept();
@@ -119,7 +119,7 @@ class server
   void start_accept()
   {
     connection::pointer new_connection =
-      connection::create(acceptor_.get_io_service(), filename_);
+      connection::create(acceptor_.get_executor().context(), filename_);
 
     acceptor_.async_accept(new_connection->socket(),
         boost::bind(&server::handle_accept, this, new_connection,
@@ -151,12 +151,12 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     using namespace std; // For atoi.
-    server s(io_service, atoi(argv[1]), argv[2]);
+    server s(io_context, atoi(argv[1]), argv[2]);
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/allocation/server.cpp b/example/cpp11/allocation/server.cpp
index c41eb8fdc9..c363a3d871 100644
--- a/example/cpp11/allocation/server.cpp
+++ b/example/cpp11/allocation/server.cpp
@@ -166,9 +166,8 @@ class session
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
-      socket_(io_service)
+  server(boost::asio::io_context& io_context, short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
   {
     do_accept();
   }
@@ -176,12 +175,12 @@ class server
 private:
   void do_accept()
   {
-    acceptor_.async_accept(socket_,
-        [this](boost::system::error_code ec)
+    acceptor_.async_accept(
+        [this](boost::system::error_code ec, tcp::socket socket)
         {
           if (!ec)
           {
-            std::make_shared<session>(std::move(socket_))->start();
+            std::make_shared<session>(std::move(socket))->start();
           }
 
           do_accept();
@@ -189,7 +188,6 @@ class server
   }
 
   tcp::acceptor acceptor_;
-  tcp::socket socket_;
 };
 
 int main(int argc, char* argv[])
@@ -202,9 +200,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
-    server s(io_service, std::atoi(argv[1]));
-    io_service.run();
+    boost::asio::io_context io_context;
+    server s(io_context, std::atoi(argv[1]));
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/buffers/reference_counted.cpp b/example/cpp11/buffers/reference_counted.cpp
index b83b1cfa39..462d5f04e1 100644
--- a/example/cpp11/buffers/reference_counted.cpp
+++ b/example/cpp11/buffers/reference_counted.cpp
@@ -72,9 +72,8 @@ class session
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
-      socket_(io_service)
+  server(boost::asio::io_context& io_context, short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
   {
     do_accept();
   }
@@ -82,12 +81,12 @@ class server
 private:
   void do_accept()
   {
-    acceptor_.async_accept(socket_,
-        [this](boost::system::error_code ec)
+    acceptor_.async_accept(
+        [this](boost::system::error_code ec, tcp::socket socket)
         {
           if (!ec)
           {
-            std::make_shared<session>(std::move(socket_))->start();
+            std::make_shared<session>(std::move(socket))->start();
           }
 
           do_accept();
@@ -95,7 +94,6 @@ class server
   }
 
   tcp::acceptor acceptor_;
-  tcp::socket socket_;
 };
 
 int main(int argc, char* argv[])
@@ -108,11 +106,11 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    server s(io_service, std::atoi(argv[1]));
+    server s(io_context, std::atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/chat/chat_client.cpp b/example/cpp11/chat/chat_client.cpp
index a41df5c1ee..a422e0f9f8 100644
--- a/example/cpp11/chat/chat_client.cpp
+++ b/example/cpp11/chat/chat_client.cpp
@@ -22,17 +22,17 @@ typedef std::deque<chat_message> chat_message_queue;
 class chat_client
 {
 public:
-  chat_client(boost::asio::io_service& io_service,
-      tcp::resolver::iterator endpoint_iterator)
-    : io_service_(io_service),
-      socket_(io_service)
+  chat_client(boost::asio::io_context& io_context,
+      const tcp::resolver::results_type& endpoints)
+    : io_context_(io_context),
+      socket_(io_context)
   {
-    do_connect(endpoint_iterator);
+    do_connect(endpoints);
   }
 
   void write(const chat_message& msg)
   {
-    io_service_.post(
+    boost::asio::post(io_context_,
         [this, msg]()
         {
           bool write_in_progress = !write_msgs_.empty();
@@ -46,14 +46,14 @@ class chat_client
 
   void close()
   {
-    io_service_.post([this]() { socket_.close(); });
+    boost::asio::post(io_context_, [this]() { socket_.close(); });
   }
 
 private:
-  void do_connect(tcp::resolver::iterator endpoint_iterator)
+  void do_connect(const tcp::resolver::results_type& endpoints)
   {
-    boost::asio::async_connect(socket_, endpoint_iterator,
-        [this](boost::system::error_code ec, tcp::resolver::iterator)
+    boost::asio::async_connect(socket_, endpoints,
+        [this](boost::system::error_code ec, tcp::endpoint)
         {
           if (!ec)
           {
@@ -121,7 +121,7 @@ class chat_client
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
   tcp::socket socket_;
   chat_message read_msg_;
   chat_message_queue write_msgs_;
@@ -137,13 +137,13 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tcp::resolver resolver(io_service);
-    auto endpoint_iterator = resolver.resolve({ argv[1], argv[2] });
-    chat_client c(io_service, endpoint_iterator);
+    tcp::resolver resolver(io_context);
+    auto endpoints = resolver.resolve(argv[1], argv[2]);
+    chat_client c(io_context, endpoints);
 
-    std::thread t([&io_service](){ io_service.run(); });
+    std::thread t([&io_context](){ io_context.run(); });
 
     char line[chat_message::max_body_length + 1];
     while (std::cin.getline(line, chat_message::max_body_length + 1))
diff --git a/example/cpp11/chat/chat_server.cpp b/example/cpp11/chat/chat_server.cpp
index 7f5dc4652b..4db62b4ba3 100644
--- a/example/cpp11/chat/chat_server.cpp
+++ b/example/cpp11/chat/chat_server.cpp
@@ -169,10 +169,9 @@ class chat_session
 class chat_server
 {
 public:
-  chat_server(boost::asio::io_service& io_service,
+  chat_server(boost::asio::io_context& io_context,
       const tcp::endpoint& endpoint)
-    : acceptor_(io_service, endpoint),
-      socket_(io_service)
+    : acceptor_(io_context, endpoint)
   {
     do_accept();
   }
@@ -180,12 +179,12 @@ class chat_server
 private:
   void do_accept()
   {
-    acceptor_.async_accept(socket_,
-        [this](boost::system::error_code ec)
+    acceptor_.async_accept(
+        [this](boost::system::error_code ec, tcp::socket socket)
         {
           if (!ec)
           {
-            std::make_shared<chat_session>(std::move(socket_), room_)->start();
+            std::make_shared<chat_session>(std::move(socket), room_)->start();
           }
 
           do_accept();
@@ -193,7 +192,6 @@ class chat_server
   }
 
   tcp::acceptor acceptor_;
-  tcp::socket socket_;
   chat_room room_;
 };
 
@@ -209,16 +207,16 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
     std::list<chat_server> servers;
     for (int i = 1; i < argc; ++i)
     {
       tcp::endpoint endpoint(tcp::v4(), std::atoi(argv[i]));
-      servers.emplace_back(io_service, endpoint);
+      servers.emplace_back(io_context, endpoint);
     }
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/echo/async_tcp_echo_server.cpp b/example/cpp11/echo/async_tcp_echo_server.cpp
index ad1a060f9c..14a3810a63 100644
--- a/example/cpp11/echo/async_tcp_echo_server.cpp
+++ b/example/cpp11/echo/async_tcp_echo_server.cpp
@@ -65,9 +65,8 @@ class session
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : acceptor_(io_service, tcp::endpoint(tcp::v4(), port)),
-      socket_(io_service)
+  server(boost::asio::io_context& io_context, short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
   {
     do_accept();
   }
@@ -75,12 +74,12 @@ class server
 private:
   void do_accept()
   {
-    acceptor_.async_accept(socket_,
-        [this](boost::system::error_code ec)
+    acceptor_.async_accept(
+        [this](boost::system::error_code ec, tcp::socket socket)
         {
           if (!ec)
           {
-            std::make_shared<session>(std::move(socket_))->start();
+            std::make_shared<session>(std::move(socket))->start();
           }
 
           do_accept();
@@ -88,7 +87,6 @@ class server
   }
 
   tcp::acceptor acceptor_;
-  tcp::socket socket_;
 };
 
 int main(int argc, char* argv[])
@@ -101,11 +99,11 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    server s(io_service, std::atoi(argv[1]));
+    server s(io_context, std::atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/echo/async_udp_echo_server.cpp b/example/cpp11/echo/async_udp_echo_server.cpp
index 4c1da78752..3e0ab89586 100644
--- a/example/cpp11/echo/async_udp_echo_server.cpp
+++ b/example/cpp11/echo/async_udp_echo_server.cpp
@@ -17,8 +17,8 @@ using boost::asio::ip::udp;
 class server
 {
 public:
-  server(boost::asio::io_service& io_service, short port)
-    : socket_(io_service, udp::endpoint(udp::v4(), port))
+  server(boost::asio::io_context& io_context, short port)
+    : socket_(io_context, udp::endpoint(udp::v4(), port))
   {
     do_receive();
   }
@@ -67,11 +67,11 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    server s(io_service, std::atoi(argv[1]));
+    server s(io_context, std::atoi(argv[1]));
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/echo/blocking_tcp_echo_client.cpp b/example/cpp11/echo/blocking_tcp_echo_client.cpp
index c6ed7f6f81..557b14e41d 100644
--- a/example/cpp11/echo/blocking_tcp_echo_client.cpp
+++ b/example/cpp11/echo/blocking_tcp_echo_client.cpp
@@ -27,11 +27,11 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    tcp::socket s(io_service);
-    tcp::resolver resolver(io_service);
-    boost::asio::connect(s, resolver.resolve({argv[1], argv[2]}));
+    tcp::socket s(io_context);
+    tcp::resolver resolver(io_context);
+    boost::asio::connect(s, resolver.resolve(argv[1], argv[2]));
 
     std::cout << "Enter message: ";
     char request[max_length];
diff --git a/example/cpp11/echo/blocking_tcp_echo_server.cpp b/example/cpp11/echo/blocking_tcp_echo_server.cpp
index b69f3ef4f4..44c69c0dae 100644
--- a/example/cpp11/echo/blocking_tcp_echo_server.cpp
+++ b/example/cpp11/echo/blocking_tcp_echo_server.cpp
@@ -42,14 +42,12 @@ void session(tcp::socket sock)
   }
 }
 
-void server(boost::asio::io_service& io_service, unsigned short port)
+void server(boost::asio::io_context& io_context, unsigned short port)
 {
-  tcp::acceptor a(io_service, tcp::endpoint(tcp::v4(), port));
+  tcp::acceptor a(io_context, tcp::endpoint(tcp::v4(), port));
   for (;;)
   {
-    tcp::socket sock(io_service);
-    a.accept(sock);
-    std::thread(session, std::move(sock)).detach();
+    std::thread(session, a.accept()).detach();
   }
 }
 
@@ -63,9 +61,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    server(io_service, std::atoi(argv[1]));
+    server(io_context, std::atoi(argv[1]));
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/echo/blocking_udp_echo_client.cpp b/example/cpp11/echo/blocking_udp_echo_client.cpp
index 4e8215a1e0..8be33a0688 100644
--- a/example/cpp11/echo/blocking_udp_echo_client.cpp
+++ b/example/cpp11/echo/blocking_udp_echo_client.cpp
@@ -27,18 +27,19 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    udp::socket s(io_service, udp::endpoint(udp::v4(), 0));
+    udp::socket s(io_context, udp::endpoint(udp::v4(), 0));
 
-    udp::resolver resolver(io_service);
-    udp::endpoint endpoint = *resolver.resolve({udp::v4(), argv[1], argv[2]});
+    udp::resolver resolver(io_context);
+    udp::resolver::results_type endpoints =
+      resolver.resolve(udp::v4(), argv[1], argv[2]);
 
     std::cout << "Enter message: ";
     char request[max_length];
     std::cin.getline(request, max_length);
     size_t request_length = std::strlen(request);
-    s.send_to(boost::asio::buffer(request, request_length), endpoint);
+    s.send_to(boost::asio::buffer(request, request_length), *endpoints.begin());
 
     char reply[max_length];
     udp::endpoint sender_endpoint;
diff --git a/example/cpp11/echo/blocking_udp_echo_server.cpp b/example/cpp11/echo/blocking_udp_echo_server.cpp
index 970f5fe579..6626d74d82 100644
--- a/example/cpp11/echo/blocking_udp_echo_server.cpp
+++ b/example/cpp11/echo/blocking_udp_echo_server.cpp
@@ -16,9 +16,9 @@ using boost::asio::ip::udp;
 
 enum { max_length = 1024 };
 
-void server(boost::asio::io_service& io_service, unsigned short port)
+void server(boost::asio::io_context& io_context, unsigned short port)
 {
-  udp::socket sock(io_service, udp::endpoint(udp::v4(), port));
+  udp::socket sock(io_context, udp::endpoint(udp::v4(), port));
   for (;;)
   {
     char data[max_length];
@@ -39,9 +39,9 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    server(io_service, std::atoi(argv[1]));
+    server(io_context, std::atoi(argv[1]));
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/futures/daytime_client.cpp b/example/cpp11/futures/daytime_client.cpp
index 34f9ff22a9..2ec8a67290 100644
--- a/example/cpp11/futures/daytime_client.cpp
+++ b/example/cpp11/futures/daytime_client.cpp
@@ -12,32 +12,32 @@
 #include <future>
 #include <iostream>
 #include <thread>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include <boost/asio/use_future.hpp>
 
 using boost::asio::ip::udp;
 
-void get_daytime(boost::asio::io_service& io_service, const char* hostname)
+void get_daytime(boost::asio::io_context& io_context, const char* hostname)
 {
   try
   {
-    udp::resolver resolver(io_service);
+    udp::resolver resolver(io_context);
 
-    std::future<udp::resolver::iterator> iter =
+    std::future<udp::resolver::results_type> endpoints =
       resolver.async_resolve(
-          {udp::v4(), hostname, "daytime"},
+          udp::v4(), hostname, "daytime",
           boost::asio::use_future);
 
-    // The async_resolve operation above returns the endpoint iterator as a
-    // future value that is not retrieved ...
+    // The async_resolve operation above returns the endpoints as a future
+    // value that is not retrieved ...
 
-    udp::socket socket(io_service, udp::v4());
+    udp::socket socket(io_context, udp::v4());
 
     std::array<char, 1> send_buf  = {{ 0 }};
     std::future<std::size_t> send_length =
       socket.async_send_to(boost::asio::buffer(send_buf),
-          *iter.get(), // ... until here. This call may block.
+          *endpoints.get().begin(), // ... until here. This call may block.
           boost::asio::use_future);
 
     // Do other things here while the send completes.
@@ -74,15 +74,15 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    // We run the io_service off in its own thread so that it operates
+    // We run the io_context off in its own thread so that it operates
     // completely asynchronously with respect to the rest of the program.
-    boost::asio::io_service io_service;
-    boost::asio::io_service::work work(io_service);
-    std::thread thread([&io_service](){ io_service.run(); });
+    boost::asio::io_context io_context;
+    auto work = boost::asio::make_work_guard(io_context);
+    std::thread thread([&io_context](){ io_context.run(); });
 
-    get_daytime(io_service, argv[1]);
+    get_daytime(io_context, argv[1]);
 
-    io_service.stop();
+    io_context.stop();
     thread.join();
   }
   catch (std::exception& e)
diff --git a/example/cpp11/http/server/server.cpp b/example/cpp11/http/server/server.cpp
index 4f761d9212..df453b8ed2 100644
--- a/example/cpp11/http/server/server.cpp
+++ b/example/cpp11/http/server/server.cpp
@@ -17,11 +17,10 @@ namespace server {
 
 server::server(const std::string& address, const std::string& port,
     const std::string& doc_root)
-  : io_service_(),
-    signals_(io_service_),
-    acceptor_(io_service_),
+  : io_context_(1),
+    signals_(io_context_),
+    acceptor_(io_context_),
     connection_manager_(),
-    socket_(io_service_),
     request_handler_(doc_root)
 {
   // Register to handle the signals that indicate when the server should exit.
@@ -36,8 +35,9 @@ server::server(const std::string& address, const std::string& port,
   do_await_stop();
 
   // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
-  boost::asio::ip::tcp::resolver resolver(io_service_);
-  boost::asio::ip::tcp::endpoint endpoint = *resolver.resolve({address, port});
+  boost::asio::ip::tcp::resolver resolver(io_context_);
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
   acceptor_.open(endpoint.protocol());
   acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
   acceptor_.bind(endpoint);
@@ -48,17 +48,17 @@ server::server(const std::string& address, const std::string& port,
 
 void server::run()
 {
-  // The io_service::run() call will block until all asynchronous operations
+  // The io_context::run() call will block until all asynchronous operations
   // have finished. While the server is running, there is always at least one
   // asynchronous operation outstanding: the asynchronous accept call waiting
   // for new incoming connections.
-  io_service_.run();
+  io_context_.run();
 }
 
 void server::do_accept()
 {
-  acceptor_.async_accept(socket_,
-      [this](boost::system::error_code ec)
+  acceptor_.async_accept(
+      [this](boost::system::error_code ec, boost::asio::ip::tcp::socket socket)
       {
         // Check whether the server was stopped by a signal before this
         // completion handler had a chance to run.
@@ -70,7 +70,7 @@ void server::do_accept()
         if (!ec)
         {
           connection_manager_.start(std::make_shared<connection>(
-              std::move(socket_), connection_manager_, request_handler_));
+              std::move(socket), connection_manager_, request_handler_));
         }
 
         do_accept();
@@ -83,7 +83,7 @@ void server::do_await_stop()
       [this](boost::system::error_code /*ec*/, int /*signo*/)
       {
         // The server is stopped by cancelling all outstanding asynchronous
-        // operations. Once all operations have finished the io_service::run()
+        // operations. Once all operations have finished the io_context::run()
         // call will exit.
         acceptor_.close();
         connection_manager_.stop_all();
diff --git a/example/cpp11/http/server/server.hpp b/example/cpp11/http/server/server.hpp
index 50d9882382..7b8aee0c5d 100644
--- a/example/cpp11/http/server/server.hpp
+++ b/example/cpp11/http/server/server.hpp
@@ -32,7 +32,7 @@ class server
   explicit server(const std::string& address, const std::string& port,
       const std::string& doc_root);
 
-  /// Run the server's io_service loop.
+  /// Run the server's io_context loop.
   void run();
 
 private:
@@ -42,8 +42,8 @@ class server
   /// Wait for a request to stop the server.
   void do_await_stop();
 
-  /// The io_service used to perform asynchronous operations.
-  boost::asio::io_service io_service_;
+  /// The io_context used to perform asynchronous operations.
+  boost::asio::io_context io_context_;
 
   /// The signal_set is used to register for process termination notifications.
   boost::asio::signal_set signals_;
@@ -54,9 +54,6 @@ class server
   /// The connection manager which owns all live connections.
   connection_manager connection_manager_;
 
-  /// The next socket to be accepted.
-  boost::asio::ip::tcp::socket socket_;
-
   /// The handler for all incoming requests.
   request_handler request_handler_;
 };
diff --git a/example/cpp11/spawn/echo_server.cpp b/example/cpp11/spawn/echo_server.cpp
index ac18373d54..350304e63e 100644
--- a/example/cpp11/spawn/echo_server.cpp
+++ b/example/cpp11/spawn/echo_server.cpp
@@ -8,7 +8,7 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/spawn.hpp>
 #include <boost/asio/steady_timer.hpp>
@@ -23,8 +23,8 @@ class session : public std::enable_shared_from_this<session>
 public:
   explicit session(tcp::socket socket)
     : socket_(std::move(socket)),
-      timer_(socket_.get_io_service()),
-      strand_(socket_.get_io_service())
+      timer_(socket_.get_io_context()),
+      strand_(socket_.get_io_context())
   {
   }
 
@@ -67,7 +67,7 @@ class session : public std::enable_shared_from_this<session>
 private:
   tcp::socket socket_;
   boost::asio::steady_timer timer_;
-  boost::asio::io_service::strand strand_;
+  boost::asio::io_context::strand strand_;
 };
 
 int main(int argc, char* argv[])
@@ -80,24 +80,24 @@ int main(int argc, char* argv[])
       return 1;
     }
 
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
 
-    boost::asio::spawn(io_service,
+    boost::asio::spawn(io_context,
         [&](boost::asio::yield_context yield)
         {
-          tcp::acceptor acceptor(io_service,
+          tcp::acceptor acceptor(io_context,
             tcp::endpoint(tcp::v4(), std::atoi(argv[1])));
 
           for (;;)
           {
             boost::system::error_code ec;
-            tcp::socket socket(io_service);
+            tcp::socket socket(io_context);
             acceptor.async_accept(socket, yield[ec]);
             if (!ec) std::make_shared<session>(std::move(socket))->go();
           }
         });
 
-    io_service.run();
+    io_context.run();
   }
   catch (std::exception& e)
   {
diff --git a/example/cpp11/spawn/parallel_grep.cpp b/example/cpp11/spawn/parallel_grep.cpp
new file mode 100644
index 0000000000..7beb114618
--- /dev/null
+++ b/example/cpp11/spawn/parallel_grep.cpp
@@ -0,0 +1,84 @@
+//
+// parallel_grep.cpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio/dispatch.hpp>
+#include <boost/asio/post.hpp>
+#include <boost/asio/spawn.hpp>
+#include <boost/asio/strand.hpp>
+#include <boost/asio/thread_pool.hpp>
+#include <fstream>
+#include <iostream>
+#include <string>
+
+using boost::asio::dispatch;
+using boost::asio::spawn;
+using boost::asio::strand;
+using boost::thread_pool;
+using boost::asio::yield_context;
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc < 2)
+    {
+      std::cerr << "Usage: parallel_grep <string> <files...>\n";
+      return 1;
+    }
+
+    // We use a fixed size pool of threads for reading the input files. The
+    // number of threads is automatically determined based on the number of
+    // CPUs available in the system.
+    thread_pool pool;
+
+    // To prevent the output from being garbled, we use a strand to synchronise
+    // printing.
+    strand<thread_pool::executor_type> output_strand(pool.get_executor());
+
+    // Spawn a new coroutine for each file specified on the command line.
+    std::string search_string = argv[1];
+    for (int argn = 2; argn < argc; ++argn)
+    {
+      std::string input_file = argv[argn];
+      spawn(pool,
+        [=](yield_context yield)
+        {
+          std::ifstream is(input_file.c_str());
+          std::string line;
+          std::size_t line_num = 0;
+          while (std::getline(is, line))
+          {
+            // If we find a match, send a message to the output.
+            if (line.find(search_string) != std::string::npos)
+            {
+              dispatch(output_strand,
+                  [=]
+                  {
+                    std::cout << input_file << ':' << line << std::endl;
+                  });
+            }
+
+            // Every so often we yield control to another coroutine.
+            if (++line_num % 10 == 0)
+              post(yield);
+          }
+        });
+    }
+
+    // Join the thread pool to wait for all the spawned tasks to complete.
+    pool.join();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}
diff --git a/include/boost/asio.hpp b/include/boost/asio.hpp
index 114d871c0c..b84f98fe42 100644
--- a/include/boost/asio.hpp
+++ b/include/boost/asio.hpp
@@ -17,6 +17,8 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/basic_datagram_socket.hpp>
 #include <boost/asio/basic_deadline_timer.hpp>
@@ -31,6 +33,7 @@
 #include <boost/asio/basic_stream_socket.hpp>
 #include <boost/asio/basic_streambuf.hpp>
 #include <boost/asio/basic_waitable_timer.hpp>
+#include <boost/asio/bind_executor.hpp>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/buffered_read_stream_fwd.hpp>
 #include <boost/asio/buffered_read_stream.hpp>
@@ -45,7 +48,12 @@
 #include <boost/asio/datagram_socket_service.hpp>
 #include <boost/asio/deadline_timer_service.hpp>
 #include <boost/asio/deadline_timer.hpp>
+#include <boost/asio/defer.hpp>
+#include <boost/asio/dispatch.hpp>
 #include <boost/asio/error.hpp>
+#include <boost/asio/execution_context.hpp>
+#include <boost/asio/executor.hpp>
+#include <boost/asio/executor_work_guard.hpp>
 #include <boost/asio/generic/basic_endpoint.hpp>
 #include <boost/asio/generic/datagram_protocol.hpp>
 #include <boost/asio/generic/raw_protocol.hpp>
@@ -55,10 +63,18 @@
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
 #include <boost/asio/handler_type.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/io_context_strand.hpp>
 #include <boost/asio/io_service.hpp>
+#include <boost/asio/io_service_strand.hpp>
 #include <boost/asio/ip/address.hpp>
 #include <boost/asio/ip/address_v4.hpp>
+#include <boost/asio/ip/address_v4_iterator.hpp>
+#include <boost/asio/ip/address_v4_range.hpp>
 #include <boost/asio/ip/address_v6.hpp>
+#include <boost/asio/ip/address_v6_iterator.hpp>
+#include <boost/asio/ip/address_v6_range.hpp>
+#include <boost/asio/ip/bad_address_cast.hpp>
 #include <boost/asio/ip/basic_endpoint.hpp>
 #include <boost/asio/ip/basic_resolver.hpp>
 #include <boost/asio/ip/basic_resolver_entry.hpp>
@@ -67,24 +83,29 @@
 #include <boost/asio/ip/host_name.hpp>
 #include <boost/asio/ip/icmp.hpp>
 #include <boost/asio/ip/multicast.hpp>
+#include <boost/asio/ip/resolver_base.hpp>
 #include <boost/asio/ip/resolver_query_base.hpp>
 #include <boost/asio/ip/resolver_service.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include <boost/asio/ip/unicast.hpp>
 #include <boost/asio/ip/v6_only.hpp>
+#include <boost/asio/is_executor.hpp>
 #include <boost/asio/is_read_buffered.hpp>
 #include <boost/asio/is_write_buffered.hpp>
 #include <boost/asio/local/basic_endpoint.hpp>
 #include <boost/asio/local/connect_pair.hpp>
 #include <boost/asio/local/datagram_protocol.hpp>
 #include <boost/asio/local/stream_protocol.hpp>
+#include <boost/asio/packaged_task.hpp>
 #include <boost/asio/placeholders.hpp>
 #include <boost/asio/posix/basic_descriptor.hpp>
 #include <boost/asio/posix/basic_stream_descriptor.hpp>
+#include <boost/asio/posix/descriptor.hpp>
 #include <boost/asio/posix/descriptor_base.hpp>
 #include <boost/asio/posix/stream_descriptor.hpp>
 #include <boost/asio/posix/stream_descriptor_service.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/raw_socket_service.hpp>
 #include <boost/asio/read.hpp>
 #include <boost/asio/read_at.hpp>
@@ -100,7 +121,12 @@
 #include <boost/asio/strand.hpp>
 #include <boost/asio/stream_socket_service.hpp>
 #include <boost/asio/streambuf.hpp>
+#include <boost/asio/system_context.hpp>
+#include <boost/asio/system_executor.hpp>
+#include <boost/asio/thread_pool.hpp>
 #include <boost/asio/time_traits.hpp>
+#include <boost/asio/use_future.hpp>
+#include <boost/asio/uses_executor.hpp>
 #include <boost/asio/version.hpp>
 #include <boost/asio/wait_traits.hpp>
 #include <boost/asio/waitable_timer_service.hpp>
@@ -110,6 +136,7 @@
 #include <boost/asio/windows/basic_stream_handle.hpp>
 #include <boost/asio/windows/object_handle.hpp>
 #include <boost/asio/windows/object_handle_service.hpp>
+#include <boost/asio/windows/overlapped_handle.hpp>
 #include <boost/asio/windows/overlapped_ptr.hpp>
 #include <boost/asio/windows/random_access_handle.hpp>
 #include <boost/asio/windows/random_access_handle_service.hpp>
diff --git a/include/boost/asio/associated_allocator.hpp b/include/boost/asio/associated_allocator.hpp
new file mode 100644
index 0000000000..b9ef5a452f
--- /dev/null
+++ b/include/boost/asio/associated_allocator.hpp
@@ -0,0 +1,133 @@
+//
+// associated_allocator.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_ASSOCIATED_ALLOCATOR_HPP
+#define BOOST_ASIO_ASSOCIATED_ALLOCATOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <memory>
+#include <boost/asio/detail/type_traits.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename>
+struct associated_allocator_check
+{
+  typedef void type;
+};
+
+template <typename T, typename E, typename = void>
+struct associated_allocator_impl
+{
+  typedef E type;
+
+  static type get(const T&, const E& e) BOOST_ASIO_NOEXCEPT
+  {
+    return e;
+  }
+};
+
+template <typename T, typename E>
+struct associated_allocator_impl<T, E,
+  typename associated_allocator_check<typename T::allocator_type>::type>
+{
+  typedef typename T::allocator_type type;
+
+  static type get(const T& t, const E&) BOOST_ASIO_NOEXCEPT
+  {
+    return t.get_allocator();
+  }
+};
+
+} // namespace detail
+
+/// Traits type used to obtain the allocator associated with an object.
+/**
+ * A program may specialise this traits type if the @c T template parameter in
+ * the specialisation is a user-defined type. The template parameter @c
+ * Allocator shall be a type meeting the Allocator requirements.
+ *
+ * Specialisations shall meet the following requirements, where @c t is a const
+ * reference to an object of type @c T, and @c a is an object of type @c
+ * Allocator.
+ *
+ * @li Provide a nested typedef @c type that identifies a type meeting the
+ * Allocator requirements.
+ *
+ * @li Provide a noexcept static member function named @c get, callable as @c
+ * get(t) and with return type @c type.
+ *
+ * @li Provide a noexcept static member function named @c get, callable as @c
+ * get(t,a) and with return type @c type.
+ */
+template <typename T, typename Allocator = std::allocator<void> >
+struct associated_allocator
+{
+  /// If @c T has a nested type @c allocator_type, <tt>T::allocator_type</tt>.
+  /// Otherwise @c Allocator.
+#if defined(GENERATING_DOCUMENTATION)
+  typedef see_below type;
+#else // defined(GENERATING_DOCUMENTATION)
+  typedef typename detail::associated_allocator_impl<T, Allocator>::type type;
+#endif // defined(GENERATING_DOCUMENTATION)
+
+  /// If @c T has a nested type @c allocator_type, returns
+  /// <tt>t.get_allocator()</tt>. Otherwise returns @c a.
+  static type get(const T& t,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return detail::associated_allocator_impl<T, Allocator>::get(t, a);
+  }
+};
+
+/// Helper function to obtain an object's associated allocator.
+/**
+ * @returns <tt>associated_allocator<T>::get(t)</tt>
+ */
+template <typename T>
+inline typename associated_allocator<T>::type
+get_associated_allocator(const T& t) BOOST_ASIO_NOEXCEPT
+{
+  return associated_allocator<T>::get(t);
+}
+
+/// Helper function to obtain an object's associated allocator.
+/**
+ * @returns <tt>associated_allocator<T, Allocator>::get(t, a)</tt>
+ */
+template <typename T, typename Allocator>
+inline typename associated_allocator<T, Allocator>::type
+get_associated_allocator(const T& t, const Allocator& a) BOOST_ASIO_NOEXCEPT
+{
+  return associated_allocator<T, Allocator>::get(t, a);
+}
+
+#if defined(BOOST_ASIO_HAS_ALIAS_TEMPLATES)
+
+template <typename T, typename Allocator = std::allocator<void> >
+using associated_allocator_t
+  = typename associated_allocator<T, Allocator>::type;
+
+#endif // defined(BOOST_ASIO_HAS_ALIAS_TEMPLATES)
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_ASSOCIATED_ALLOCATOR_HPP
diff --git a/include/boost/asio/associated_executor.hpp b/include/boost/asio/associated_executor.hpp
new file mode 100644
index 0000000000..d0347afcfa
--- /dev/null
+++ b/include/boost/asio/associated_executor.hpp
@@ -0,0 +1,151 @@
+//
+// associated_executor.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_ASSOCIATED_EXECUTOR_HPP
+#define BOOST_ASIO_ASSOCIATED_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/is_executor.hpp>
+#include <boost/asio/system_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename>
+struct associated_executor_check
+{
+  typedef void type;
+};
+
+template <typename T, typename E, typename = void>
+struct associated_executor_impl
+{
+  typedef E type;
+
+  static type get(const T&, const E& e) BOOST_ASIO_NOEXCEPT
+  {
+    return e;
+  }
+};
+
+template <typename T, typename E>
+struct associated_executor_impl<T, E,
+  typename associated_executor_check<typename T::executor_type>::type>
+{
+  typedef typename T::executor_type type;
+
+  static type get(const T& t, const E&) BOOST_ASIO_NOEXCEPT
+  {
+    return t.get_executor();
+  }
+};
+
+} // namespace detail
+
+/// Traits type used to obtain the executor associated with an object.
+/**
+ * A program may specialise this traits type if the @c T template parameter in
+ * the specialisation is a user-defined type. The template parameter @c
+ * Executor shall be a type meeting the Executor requirements.
+ *
+ * Specialisations shall meet the following requirements, where @c t is a const
+ * reference to an object of type @c T, and @c e is an object of type @c
+ * Executor.
+ *
+ * @li Provide a nested typedef @c type that identifies a type meeting the
+ * Executor requirements.
+ *
+ * @li Provide a noexcept static member function named @c get, callable as @c
+ * get(t) and with return type @c type.
+ *
+ * @li Provide a noexcept static member function named @c get, callable as @c
+ * get(t,e) and with return type @c type.
+ */
+template <typename T, typename Executor = system_executor>
+struct associated_executor
+{
+  /// If @c T has a nested type @c executor_type, <tt>T::executor_type</tt>.
+  /// Otherwise @c Executor.
+#if defined(GENERATING_DOCUMENTATION)
+  typedef see_below type;
+#else // defined(GENERATING_DOCUMENTATION)
+  typedef typename detail::associated_executor_impl<T, Executor>::type type;
+#endif // defined(GENERATING_DOCUMENTATION)
+
+  /// If @c T has a nested type @c executor_type, returns
+  /// <tt>t.get_executor()</tt>. Otherwise returns @c ex.
+  static type get(const T& t,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return detail::associated_executor_impl<T, Executor>::get(t, ex);
+  }
+};
+
+/// Helper function to obtain an object's associated executor.
+/**
+ * @returns <tt>associated_executor<T>::get(t)</tt>
+ */
+template <typename T>
+inline typename associated_executor<T>::type
+get_associated_executor(const T& t) BOOST_ASIO_NOEXCEPT
+{
+  return associated_executor<T>::get(t);
+}
+
+/// Helper function to obtain an object's associated executor.
+/**
+ * @returns <tt>associated_executor<T, Executor>::get(t, ex)</tt>
+ */
+template <typename T, typename Executor>
+inline typename associated_executor<T, Executor>::type
+get_associated_executor(const T& t, const Executor& ex,
+    typename enable_if<is_executor<
+      Executor>::value>::type* = 0) BOOST_ASIO_NOEXCEPT
+{
+  return associated_executor<T, Executor>::get(t, ex);
+}
+
+/// Helper function to obtain an object's associated executor.
+/**
+ * @returns <tt>associated_executor<T, typename
+ * ExecutionContext::executor_type>::get(t, ctx.get_executor())</tt>
+ */
+template <typename T, typename ExecutionContext>
+inline typename associated_executor<T,
+  typename ExecutionContext::executor_type>::type
+get_associated_executor(const T& t, ExecutionContext& ctx,
+    typename enable_if<is_convertible<ExecutionContext&,
+      execution_context&>::value>::type* = 0) BOOST_ASIO_NOEXCEPT
+{
+  return associated_executor<T,
+    typename ExecutionContext::executor_type>::get(t, ctx.get_executor());
+}
+
+#if defined(BOOST_ASIO_HAS_ALIAS_TEMPLATES)
+
+template <typename T, typename Executor = system_executor>
+using associated_executor_t = typename associated_executor<T, Executor>::type;
+
+#endif // defined(BOOST_ASIO_HAS_ALIAS_TEMPLATES)
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_ASSOCIATED_EXECUTOR_HPP
diff --git a/include/boost/asio/async_result.hpp b/include/boost/asio/async_result.hpp
index 6290b8462a..f49f2eb2e0 100644
--- a/include/boost/asio/async_result.hpp
+++ b/include/boost/asio/async_result.hpp
@@ -16,6 +16,7 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/handler_type.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -24,11 +25,94 @@ namespace boost {
 namespace asio {
 
 /// An interface for customising the behaviour of an initiating function.
+/**
+ * The async_result traits class is used for determining:
+ *
+ * @li the concrete completion handler type to be called at the end of the
+ * asynchronous operation;
+ *
+ * @li the initiating function return type; and
+ *
+ * @li how the return value of the initiating function is obtained.
+ *
+ * The trait allows the handler and return types to be determined at the point
+ * where the specific completion handler signature is known.
+ *
+ * This template may be specialised for user-defined completion token types.
+ * The primary template assumes that the CompletionToken is the completion
+ * handler.
+ */
+#if defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+template <typename CompletionToken, typename Signature>
+#else // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+template <typename CompletionToken, typename Signature = void>
+#endif // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+class async_result
+{
+public:
+#if defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+  /// The concrete completion handler type for the specific signature.
+  typedef CompletionToken completion_handler_type;
+
+  /// The return type of the initiating function.
+  typedef void return_type;
+#else // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+  // For backward compatibility, determine the concrete completion handler type
+  // by using the legacy handler_type trait.
+  typedef typename handler_type<CompletionToken, Signature>::type
+    completion_handler_type;
+
+  // For backward compatibility, determine the initiating function return type
+  // using the legacy single-parameter version of async_result.
+  typedef typename async_result<completion_handler_type>::type return_type;
+#endif // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+
+  /// Construct an async result from a given handler.
+  /**
+   * When using a specalised async_result, the constructor has an opportunity
+   * to initialise some state associated with the completion handler, which is
+   * then returned from the initiating function.
+   */
+  explicit async_result(completion_handler_type& h)
+#if defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+    // No data members to initialise.
+#else // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+    : legacy_result_(h)
+#endif // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+  {
+    (void)h;
+  }
+
+  /// Obtain the value to be returned from the initiating function.
+  return_type get()
+  {
+#if defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+    // Nothing to do.
+#else // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+    return legacy_result_.get();
+#endif // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+  }
+
+private:
+  async_result(const async_result&) BOOST_ASIO_DELETED;
+  async_result& operator=(const async_result&) BOOST_ASIO_DELETED;
+
+#if defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+  // No data members.
+#else // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+  async_result<completion_handler_type> legacy_result_;
+#endif // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+};
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+/// (Deprecated: Use two-parameter version of async_result.) An interface for
+/// customising the behaviour of an initiating function.
 /**
  * This template may be specialised for user-defined handler types.
  */
 template <typename Handler>
-class async_result
+class async_result<Handler>
 {
 public:
   /// The return type of the initiating function.
@@ -50,29 +134,65 @@ class async_result
   }
 };
 
-namespace detail {
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-// Helper template to deduce the true type of a handler, capture a local copy
-// of the handler, and then create an async_result for the handler.
-template <typename Handler, typename Signature>
-struct async_result_init
+/// Helper template to deduce the handler type from a CompletionToken, capture
+/// a local copy of the handler, and then create an async_result for the
+/// handler.
+template <typename CompletionToken, typename Signature>
+struct async_completion
 {
-  explicit async_result_init(BOOST_ASIO_MOVE_ARG(Handler) orig_handler)
-    : handler(BOOST_ASIO_MOVE_CAST(Handler)(orig_handler)),
-      result(handler)
+  /// The real handler type to be used for the asynchronous operation.
+  typedef typename boost::asio::async_result<
+    typename decay<CompletionToken>::type,
+      Signature>::completion_handler_type completion_handler_type;
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Constructor.
+  /**
+   * The constructor creates the concrete completion handler and makes the link
+   * between the handler and the asynchronous result.
+   */
+  explicit async_completion(CompletionToken& token)
+    : completion_handler(static_cast<typename conditional<
+        is_same<CompletionToken, completion_handler_type>::value,
+        completion_handler_type&, CompletionToken&&>::type>(token)),
+      result(completion_handler)
+  {
+  }
+#else // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  explicit async_completion(typename decay<CompletionToken>::type& token)
+    : completion_handler(token),
+      result(completion_handler)
   {
   }
 
-  typename handler_type<Handler, Signature>::type handler;
-  async_result<typename handler_type<Handler, Signature>::type> result;
+  explicit async_completion(const typename decay<CompletionToken>::type& token)
+    : completion_handler(token),
+      result(completion_handler)
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// A copy of, or reference to, a real handler object.
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  typename conditional<
+    is_same<CompletionToken, completion_handler_type>::value,
+    completion_handler_type&, completion_handler_type>::type completion_handler;
+#else // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  completion_handler_type completion_handler;
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// The result of the asynchronous operation's initiating function.
+  async_result<typename decay<CompletionToken>::type, Signature> result;
 };
 
-template <typename Handler, typename Signature>
-struct async_result_type_helper
+namespace detail {
+
+template <typename CompletionToken, typename Signature>
+struct async_result_helper
+  : async_result<typename decay<CompletionToken>::type, Signature>
 {
-  typedef typename async_result<
-      typename handler_type<Handler, Signature>::type
-    >::type type;
 };
 
 } // namespace detail
@@ -82,15 +202,22 @@ struct async_result_type_helper
 #include <boost/asio/detail/pop_options.hpp>
 
 #if defined(GENERATING_DOCUMENTATION)
-# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \
+# define BOOST_ASIO_INITFN_RESULT_TYPE(ct, sig) \
   void_or_deduced
 #elif defined(_MSC_VER) && (_MSC_VER < 1500)
-# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \
-  typename ::boost::asio::detail::async_result_type_helper<h, sig>::type
+# define BOOST_ASIO_INITFN_RESULT_TYPE(ct, sig) \
+  typename ::boost::asio::detail::async_result_helper< \
+    ct, sig>::return_type
+#define BOOST_ASIO_HANDLER_TYPE(ct, sig) \
+  typename ::boost::asio::detail::async_result_helper< \
+    ct, sig>::completion_handler_type
 #else
-# define BOOST_ASIO_INITFN_RESULT_TYPE(h, sig) \
+# define BOOST_ASIO_INITFN_RESULT_TYPE(ct, sig) \
+  typename ::boost::asio::async_result< \
+    typename ::boost::asio::decay<ct>::type, sig>::return_type
+#define BOOST_ASIO_HANDLER_TYPE(ct, sig) \
   typename ::boost::asio::async_result< \
-    typename ::boost::asio::handler_type<h, sig>::type>::type
+    typename ::boost::asio::decay<ct>::type, sig>::completion_handler_type
 #endif
 
 #endif // BOOST_ASIO_ASYNC_RESULT_HPP
diff --git a/include/boost/asio/basic_datagram_socket.hpp b/include/boost/asio/basic_datagram_socket.hpp
index 22801ee081..c2aa00bf48 100644
--- a/include/boost/asio/basic_datagram_socket.hpp
+++ b/include/boost/asio/basic_datagram_socket.hpp
@@ -18,12 +18,15 @@
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
 #include <boost/asio/basic_socket.hpp>
-#include <boost/asio/datagram_socket_service.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/datagram_socket_service.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -38,18 +41,19 @@ namespace asio {
  * @e Distinct @e objects: Safe.@n
  * @e Shared @e objects: Unsafe.
  */
-template <typename Protocol,
-    typename DatagramSocketService = datagram_socket_service<Protocol> >
+template <typename Protocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= datagram_socket_service<Protocol>)>
 class basic_datagram_socket
-  : public basic_socket<Protocol, DatagramSocketService>
+  : public basic_socket<Protocol BOOST_ASIO_SVC_TARG>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// socket.
-  typedef typename DatagramSocketService::native_handle_type native_type;
-
   /// The native representation of a socket.
-  typedef typename DatagramSocketService::native_handle_type native_handle_type;
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef typename basic_socket<
+    Protocol BOOST_ASIO_SVC_TARG>::native_handle_type native_handle_type;
+#endif
 
   /// The protocol type.
   typedef Protocol protocol_type;
@@ -62,12 +66,12 @@ class basic_datagram_socket
    * This constructor creates a datagram socket without opening it. The open()
    * function must be called before data can be sent or received on the socket.
    *
-   * @param io_service The io_service object that the datagram socket will use
+   * @param io_context The io_context object that the datagram socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    */
-  explicit basic_datagram_socket(boost::asio::io_service& io_service)
-    : basic_socket<Protocol, DatagramSocketService>(io_service)
+  explicit basic_datagram_socket(boost::asio::io_context& io_context)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context)
   {
   }
 
@@ -75,7 +79,7 @@ class basic_datagram_socket
   /**
    * This constructor creates and opens a datagram socket.
    *
-   * @param io_service The io_service object that the datagram socket will use
+   * @param io_context The io_context object that the datagram socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    *
@@ -83,9 +87,9 @@ class basic_datagram_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_datagram_socket(boost::asio::io_service& io_service,
+  basic_datagram_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol)
-    : basic_socket<Protocol, DatagramSocketService>(io_service, protocol)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, protocol)
   {
   }
 
@@ -96,7 +100,7 @@ class basic_datagram_socket
    * to the specified endpoint on the local machine. The protocol used is the
    * protocol associated with the given endpoint.
    *
-   * @param io_service The io_service object that the datagram socket will use
+   * @param io_context The io_context object that the datagram socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    *
@@ -105,9 +109,9 @@ class basic_datagram_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_datagram_socket(boost::asio::io_service& io_service,
+  basic_datagram_socket(boost::asio::io_context& io_context,
       const endpoint_type& endpoint)
-    : basic_socket<Protocol, DatagramSocketService>(io_service, endpoint)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, endpoint)
   {
   }
 
@@ -116,7 +120,7 @@ class basic_datagram_socket
    * This constructor creates a datagram socket object to hold an existing
    * native socket.
    *
-   * @param io_service The io_service object that the datagram socket will use
+   * @param io_context The io_context object that the datagram socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    *
@@ -126,10 +130,10 @@ class basic_datagram_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_datagram_socket(boost::asio::io_service& io_service,
+  basic_datagram_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol, const native_handle_type& native_socket)
-    : basic_socket<Protocol, DatagramSocketService>(
-        io_service, protocol, native_socket)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(
+        io_context, protocol, native_socket)
   {
   }
 
@@ -142,11 +146,10 @@ class basic_datagram_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_datagram_socket(io_service&) constructor.
+   * constructed using the @c basic_datagram_socket(io_context&) constructor.
    */
   basic_datagram_socket(basic_datagram_socket&& other)
-    : basic_socket<Protocol, DatagramSocketService>(
-        BOOST_ASIO_MOVE_CAST(basic_datagram_socket)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -159,12 +162,11 @@ class basic_datagram_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_datagram_socket(io_service&) constructor.
+   * constructed using the @c basic_datagram_socket(io_context&) constructor.
    */
   basic_datagram_socket& operator=(basic_datagram_socket&& other)
   {
-    basic_socket<Protocol, DatagramSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_datagram_socket)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 
@@ -177,15 +179,13 @@ class basic_datagram_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_datagram_socket(io_service&) constructor.
+   * constructed using the @c basic_datagram_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename DatagramSocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   basic_datagram_socket(
-      basic_datagram_socket<Protocol1, DatagramSocketService1>&& other,
+      basic_datagram_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other,
       typename enable_if<is_convertible<Protocol1, Protocol>::value>::type* = 0)
-    : basic_socket<Protocol, DatagramSocketService>(
-        BOOST_ASIO_MOVE_CAST2(basic_datagram_socket<
-          Protocol1, DatagramSocketService1>)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -199,20 +199,27 @@ class basic_datagram_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_datagram_socket(io_service&) constructor.
+   * constructed using the @c basic_datagram_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename DatagramSocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   typename enable_if<is_convertible<Protocol1, Protocol>::value,
       basic_datagram_socket>::type& operator=(
-        basic_datagram_socket<Protocol1, DatagramSocketService1>&& other)
+        basic_datagram_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other)
   {
-    basic_socket<Protocol, DatagramSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST2(basic_datagram_socket<
-          Protocol1, DatagramSocketService1>)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
+  /// Destroys the socket.
+  /**
+   * This function destroys the socket, cancelling any outstanding asynchronous
+   * operations associated with the socket as if by calling @c cancel.
+   */
+  ~basic_datagram_socket()
+  {
+  }
+
   /// Send some data on a connected socket.
   /**
    * This function is used to send data on the datagram socket. The function
@@ -318,7 +325,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_send operation can only be used with a connected socket.
    * Use the async_send_to function to send data on an unconnected datagram
@@ -343,8 +350,18 @@ class basic_datagram_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(this->get_implementation(),
         buffers, 0, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(this->get_implementation(),
+        buffers, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous send on a connected socket.
@@ -369,7 +386,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_send operation can only be used with a connected socket.
    * Use the async_send_to function to send data on an unconnected datagram
@@ -386,8 +403,18 @@ class basic_datagram_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(this->get_implementation(),
         buffers, flags, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(this->get_implementation(),
+        buffers, flags, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Send a datagram to the specified endpoint.
@@ -501,7 +528,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * To send a single data buffer use the @ref buffer function as follows:
@@ -526,9 +553,20 @@ class basic_datagram_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send_to(
         this->get_implementation(), buffers, destination, 0,
         BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send_to(
+        this->get_implementation(), buffers, destination, 0,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous send.
@@ -556,7 +594,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename ConstBufferSequence, typename WriteHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
@@ -569,9 +607,20 @@ class basic_datagram_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send_to(
         this->get_implementation(), buffers, destination, flags,
         BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send_to(
+        this->get_implementation(), buffers, destination, flags,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Receive some data on a connected socket.
@@ -683,7 +732,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_receive operation can only be used with a connected socket.
    * Use the async_receive_from function to receive data on an unconnected
@@ -709,8 +758,18 @@ class basic_datagram_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(this->get_implementation(),
         buffers, 0, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive(this->get_implementation(),
+        buffers, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous receive on a connected socket.
@@ -735,7 +794,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_receive operation can only be used with a connected socket.
    * Use the async_receive_from function to receive data on an unconnected
@@ -752,8 +811,18 @@ class basic_datagram_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(this->get_implementation(),
         buffers, flags, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive(this->get_implementation(),
+        buffers, flags, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Receive a datagram with the endpoint of the sender.
@@ -870,7 +939,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * To receive into a single data buffer use the @ref buffer function as
@@ -892,9 +961,20 @@ class basic_datagram_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive_from(
         this->get_implementation(), buffers, sender_endpoint, 0,
         BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive_from(
+        this->get_implementation(), buffers, sender_endpoint, 0,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous receive.
@@ -924,7 +1004,7 @@ class basic_datagram_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename MutableBufferSequence, typename ReadHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
@@ -937,9 +1017,20 @@ class basic_datagram_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive_from(
         this->get_implementation(), buffers, sender_endpoint, flags,
         BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive_from(
+        this->get_implementation(), buffers, sender_endpoint, flags,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 };
 
diff --git a/include/boost/asio/basic_deadline_timer.hpp b/include/boost/asio/basic_deadline_timer.hpp
index 930370046b..f7179a853e 100644
--- a/include/boost/asio/basic_deadline_timer.hpp
+++ b/include/boost/asio/basic_deadline_timer.hpp
@@ -22,10 +22,17 @@
 
 #include <cstddef>
 #include <boost/asio/basic_io_object.hpp>
-#include <boost/asio/deadline_timer_service.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
+#include <boost/asio/time_traits.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/deadline_timer_service.hpp>
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/detail/deadline_timer_service.hpp>
+# define BOOST_ASIO_SVC_T detail::deadline_timer_service<TimeTraits>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -51,7 +58,7 @@ namespace asio {
  * Performing a blocking wait:
  * @code
  * // Construct a timer without setting an expiry time.
- * boost::asio::deadline_timer timer(io_service);
+ * boost::asio::deadline_timer timer(io_context);
  *
  * // Set an expiry time relative to now.
  * timer.expires_from_now(boost::posix_time::seconds(5));
@@ -74,7 +81,7 @@ namespace asio {
  * ...
  *
  * // Construct a timer with an absolute expiry time.
- * boost::asio::deadline_timer timer(io_service,
+ * boost::asio::deadline_timer timer(io_context,
  *     boost::posix_time::time_from_string("2005-12-07 23:59:59.000"));
  *
  * // Start an asynchronous wait.
@@ -121,12 +128,15 @@ namespace asio {
  * it contains the value boost::asio::error::operation_aborted.
  */
 template <typename Time,
-    typename TimeTraits = boost::asio::time_traits<Time>,
-    typename TimerService = deadline_timer_service<Time, TimeTraits> >
+    typename TimeTraits = boost::asio::time_traits<Time>
+    BOOST_ASIO_SVC_TPARAM_DEF2(= deadline_timer_service<Time, TimeTraits>)>
 class basic_deadline_timer
-  : public basic_io_object<TimerService>
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>
 {
 public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
   /// The time traits type.
   typedef TimeTraits traits_type;
 
@@ -142,11 +152,11 @@ class basic_deadline_timer
    * expires_at() or expires_from_now() functions must be called to set an
    * expiry time before the timer can be waited on.
    *
-   * @param io_service The io_service object that the timer will use to dispatch
+   * @param io_context The io_context object that the timer will use to dispatch
    * handlers for any asynchronous operations performed on the timer.
    */
-  explicit basic_deadline_timer(boost::asio::io_service& io_service)
-    : basic_io_object<TimerService>(io_service)
+  explicit basic_deadline_timer(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
   }
 
@@ -154,18 +164,18 @@ class basic_deadline_timer
   /**
    * This constructor creates a timer and sets the expiry time.
    *
-   * @param io_service The io_service object that the timer will use to dispatch
+   * @param io_context The io_context object that the timer will use to dispatch
    * handlers for any asynchronous operations performed on the timer.
    *
    * @param expiry_time The expiry time to be used for the timer, expressed
    * as an absolute time.
    */
-  basic_deadline_timer(boost::asio::io_service& io_service,
+  basic_deadline_timer(boost::asio::io_context& io_context,
       const time_type& expiry_time)
-    : basic_io_object<TimerService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
-    this->service.expires_at(this->implementation, expiry_time, ec);
+    this->get_service().expires_at(this->get_implementation(), expiry_time, ec);
     boost::asio::detail::throw_error(ec, "expires_at");
   }
 
@@ -173,21 +183,105 @@ class basic_deadline_timer
   /**
    * This constructor creates a timer and sets the expiry time.
    *
-   * @param io_service The io_service object that the timer will use to dispatch
+   * @param io_context The io_context object that the timer will use to dispatch
    * handlers for any asynchronous operations performed on the timer.
    *
    * @param expiry_time The expiry time to be used for the timer, relative to
    * now.
    */
-  basic_deadline_timer(boost::asio::io_service& io_service,
+  basic_deadline_timer(boost::asio::io_context& io_context,
       const duration_type& expiry_time)
-    : basic_io_object<TimerService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
-    this->service.expires_from_now(this->implementation, expiry_time, ec);
+    this->get_service().expires_from_now(
+        this->get_implementation(), expiry_time, ec);
     boost::asio::detail::throw_error(ec, "expires_from_now");
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a basic_deadline_timer from another.
+  /**
+   * This constructor moves a timer from one object to another.
+   *
+   * @param other The other basic_deadline_timer object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c basic_deadline_timer(io_context&) constructor.
+   */
+  basic_deadline_timer(basic_deadline_timer&& other)
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
+  {
+  }
+
+  /// Move-assign a basic_deadline_timer from another.
+  /**
+   * This assignment operator moves a timer from one object to another. Cancels
+   * any outstanding asynchronous operations associated with the target object.
+   *
+   * @param other The other basic_deadline_timer object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c basic_deadline_timer(io_context&) constructor.
+   */
+  basic_deadline_timer& operator=(basic_deadline_timer&& other)
+  {
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Destroys the timer.
+  /**
+   * This function destroys the timer, cancelling any outstanding asynchronous
+   * wait operations associated with the timer as if by calling @c cancel.
+   */
+  ~basic_deadline_timer()
+  {
+  }
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  // These functions are provided by basic_io_object<>.
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
   /// Cancel any asynchronous operations that are waiting on the timer.
   /**
    * This function forces the completion of any pending asynchronous wait
@@ -213,7 +307,7 @@ class basic_deadline_timer
   std::size_t cancel()
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.cancel(this->implementation, ec);
+    std::size_t s = this->get_service().cancel(this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "cancel");
     return s;
   }
@@ -242,7 +336,7 @@ class basic_deadline_timer
    */
   std::size_t cancel(boost::system::error_code& ec)
   {
-    return this->service.cancel(this->implementation, ec);
+    return this->get_service().cancel(this->get_implementation(), ec);
   }
 
   /// Cancels one asynchronous operation that is waiting on the timer.
@@ -272,7 +366,8 @@ class basic_deadline_timer
   std::size_t cancel_one()
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.cancel_one(this->implementation, ec);
+    std::size_t s = this->get_service().cancel_one(
+        this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "cancel_one");
     return s;
   }
@@ -303,7 +398,7 @@ class basic_deadline_timer
    */
   std::size_t cancel_one(boost::system::error_code& ec)
   {
-    return this->service.cancel_one(this->implementation, ec);
+    return this->get_service().cancel_one(this->get_implementation(), ec);
   }
 
   /// Get the timer's expiry time as an absolute time.
@@ -313,7 +408,7 @@ class basic_deadline_timer
    */
   time_type expires_at() const
   {
-    return this->service.expires_at(this->implementation);
+    return this->get_service().expires_at(this->get_implementation());
   }
 
   /// Set the timer's expiry time as an absolute time.
@@ -341,8 +436,8 @@ class basic_deadline_timer
   std::size_t expires_at(const time_type& expiry_time)
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.expires_at(
-        this->implementation, expiry_time, ec);
+    std::size_t s = this->get_service().expires_at(
+        this->get_implementation(), expiry_time, ec);
     boost::asio::detail::throw_error(ec, "expires_at");
     return s;
   }
@@ -372,7 +467,8 @@ class basic_deadline_timer
   std::size_t expires_at(const time_type& expiry_time,
       boost::system::error_code& ec)
   {
-    return this->service.expires_at(this->implementation, expiry_time, ec);
+    return this->get_service().expires_at(
+        this->get_implementation(), expiry_time, ec);
   }
 
   /// Get the timer's expiry time relative to now.
@@ -382,7 +478,7 @@ class basic_deadline_timer
    */
   duration_type expires_from_now() const
   {
-    return this->service.expires_from_now(this->implementation);
+    return this->get_service().expires_from_now(this->get_implementation());
   }
 
   /// Set the timer's expiry time relative to now.
@@ -410,8 +506,8 @@ class basic_deadline_timer
   std::size_t expires_from_now(const duration_type& expiry_time)
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.expires_from_now(
-        this->implementation, expiry_time, ec);
+    std::size_t s = this->get_service().expires_from_now(
+        this->get_implementation(), expiry_time, ec);
     boost::asio::detail::throw_error(ec, "expires_from_now");
     return s;
   }
@@ -441,8 +537,8 @@ class basic_deadline_timer
   std::size_t expires_from_now(const duration_type& expiry_time,
       boost::system::error_code& ec)
   {
-    return this->service.expires_from_now(
-        this->implementation, expiry_time, ec);
+    return this->get_service().expires_from_now(
+        this->get_implementation(), expiry_time, ec);
   }
 
   /// Perform a blocking wait on the timer.
@@ -455,7 +551,7 @@ class basic_deadline_timer
   void wait()
   {
     boost::system::error_code ec;
-    this->service.wait(this->implementation, ec);
+    this->get_service().wait(this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "wait");
   }
 
@@ -468,7 +564,7 @@ class basic_deadline_timer
    */
   void wait(boost::system::error_code& ec)
   {
-    this->service.wait(this->implementation, ec);
+    this->get_service().wait(this->get_implementation(), ec);
   }
 
   /// Start an asynchronous wait on the timer.
@@ -493,7 +589,7 @@ class basic_deadline_timer
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename WaitHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
@@ -504,8 +600,18 @@ class basic_deadline_timer
     // not meet the documented type requirements for a WaitHandler.
     BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
 
-    return this->service.async_wait(this->implementation,
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_wait(this->get_implementation(),
         BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_wait(this->get_implementation(),
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 };
 
@@ -514,6 +620,10 @@ class basic_deadline_timer
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# undef BOOST_ASIO_SVC_T
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
        // || defined(GENERATING_DOCUMENTATION)
 
diff --git a/include/boost/asio/basic_io_object.hpp b/include/boost/asio/basic_io_object.hpp
index d490a161f6..87653b5c53 100644
--- a/include/boost/asio/basic_io_object.hpp
+++ b/include/boost/asio/basic_io_object.hpp
@@ -16,7 +16,7 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -68,17 +68,43 @@ class basic_io_object
   /// The underlying implementation type of I/O object.
   typedef typename service_type::implementation_type implementation_type;
 
-  /// Get the io_service associated with the object.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
   /**
-   * This function may be used to obtain the io_service object that the I/O
+   * This function may be used to obtain the io_context object that the I/O
    * object uses to dispatch handlers for asynchronous operations.
    *
-   * @return A reference to the io_service object that the I/O object will use
+   * @return A reference to the io_context object that the I/O object will use
    * to dispatch handlers. Ownership is not transferred to the caller.
    */
-  boost::asio::io_service& get_io_service()
+  boost::asio::io_context& get_io_context()
   {
-    return service.get_io_service();
+    return service_.get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return service_.get_io_context();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// The type of the executor associated with the object.
+  typedef boost::asio::io_context::executor_type executor_type;
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return service_.get_io_context().get_executor();
   }
 
 protected:
@@ -87,10 +113,10 @@ class basic_io_object
    * Performs:
    * @code get_service().construct(get_implementation()); @endcode
    */
-  explicit basic_io_object(boost::asio::io_service& io_service)
-    : service(boost::asio::use_service<IoObjectService>(io_service))
+  explicit basic_io_object(boost::asio::io_context& io_context)
+    : service_(boost::asio::use_service<IoObjectService>(io_context))
   {
-    service.construct(implementation);
+    service_.construct(implementation_);
   }
 
 #if defined(GENERATING_DOCUMENTATION)
@@ -127,47 +153,42 @@ class basic_io_object
    */
   ~basic_io_object()
   {
-    service.destroy(implementation);
+    service_.destroy(implementation_);
   }
 
   /// Get the service associated with the I/O object.
   service_type& get_service()
   {
-    return service;
+    return service_;
   }
 
   /// Get the service associated with the I/O object.
   const service_type& get_service() const
   {
-    return service;
+    return service_;
   }
 
-  /// (Deprecated: Use get_service().) The service associated with the I/O
-  /// object.
-  /**
-   * @note Available only for services that do not support movability.
-   */
-  service_type& service;
-
   /// Get the underlying implementation of the I/O object.
   implementation_type& get_implementation()
   {
-    return implementation;
+    return implementation_;
   }
 
   /// Get the underlying implementation of the I/O object.
   const implementation_type& get_implementation() const
   {
-    return implementation;
+    return implementation_;
   }
 
-  /// (Deprecated: Use get_implementation().) The underlying implementation of
-  /// the I/O object.
-  implementation_type implementation;
-
 private:
   basic_io_object(const basic_io_object&);
   basic_io_object& operator=(const basic_io_object&);
+
+  // The service associated with the I/O object.
+  service_type& service_;
+
+  /// The underlying implementation of the I/O object.
+  implementation_type implementation_;
 };
 
 #if defined(BOOST_ASIO_HAS_MOVE)
@@ -179,43 +200,57 @@ class basic_io_object<IoObjectService, true>
   typedef IoObjectService service_type;
   typedef typename service_type::implementation_type implementation_type;
 
-  boost::asio::io_service& get_io_service()
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  boost::asio::io_context& get_io_context()
+  {
+    return service_->get_io_context();
+  }
+
+  boost::asio::io_context& get_io_service()
   {
-    return service_->get_io_service();
+    return service_->get_io_context();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  typedef boost::asio::io_context::executor_type executor_type;
+
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return service_->get_io_context().get_executor();
   }
 
 protected:
-  explicit basic_io_object(boost::asio::io_service& io_service)
-    : service_(&boost::asio::use_service<IoObjectService>(io_service))
+  explicit basic_io_object(boost::asio::io_context& io_context)
+    : service_(&boost::asio::use_service<IoObjectService>(io_context))
   {
-    service_->construct(implementation);
+    service_->construct(implementation_);
   }
 
   basic_io_object(basic_io_object&& other)
     : service_(&other.get_service())
   {
-    service_->move_construct(implementation, other.implementation);
+    service_->move_construct(implementation_, other.implementation_);
   }
 
   template <typename IoObjectService1>
   basic_io_object(IoObjectService1& other_service,
       typename IoObjectService1::implementation_type& other_implementation)
     : service_(&boost::asio::use_service<IoObjectService>(
-          other_service.get_io_service()))
+          other_service.get_io_context()))
   {
-    service_->converting_move_construct(implementation,
+    service_->converting_move_construct(implementation_,
         other_service, other_implementation);
   }
 
   ~basic_io_object()
   {
-    service_->destroy(implementation);
+    service_->destroy(implementation_);
   }
 
   basic_io_object& operator=(basic_io_object&& other)
   {
-    service_->move_assign(implementation,
-        *other.service_, other.implementation);
+    service_->move_assign(implementation_,
+        *other.service_, other.implementation_);
     service_ = other.service_;
     return *this;
   }
@@ -232,21 +267,20 @@ class basic_io_object<IoObjectService, true>
 
   implementation_type& get_implementation()
   {
-    return implementation;
+    return implementation_;
   }
 
   const implementation_type& get_implementation() const
   {
-    return implementation;
+    return implementation_;
   }
 
-  implementation_type implementation;
-
 private:
   basic_io_object(const basic_io_object&);
   void operator=(const basic_io_object&);
 
   IoObjectService* service_;
+  implementation_type implementation_;
 };
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
diff --git a/include/boost/asio/basic_raw_socket.hpp b/include/boost/asio/basic_raw_socket.hpp
index 85f8f42642..09058de224 100644
--- a/include/boost/asio/basic_raw_socket.hpp
+++ b/include/boost/asio/basic_raw_socket.hpp
@@ -22,7 +22,10 @@
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/raw_socket_service.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/raw_socket_service.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -38,18 +41,19 @@ namespace asio {
  * @e Distinct @e objects: Safe.@n
  * @e Shared @e objects: Unsafe.
  */
-template <typename Protocol,
-    typename RawSocketService = raw_socket_service<Protocol> >
+template <typename Protocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= raw_socket_service<Protocol>)>
 class basic_raw_socket
-  : public basic_socket<Protocol, RawSocketService>
+  : public basic_socket<Protocol BOOST_ASIO_SVC_TARG>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// socket.
-  typedef typename RawSocketService::native_handle_type native_type;
-
   /// The native representation of a socket.
-  typedef typename RawSocketService::native_handle_type native_handle_type;
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef typename basic_socket<
+    Protocol BOOST_ASIO_SVC_TARG>::native_handle_type native_handle_type;
+#endif
 
   /// The protocol type.
   typedef Protocol protocol_type;
@@ -62,12 +66,12 @@ class basic_raw_socket
    * This constructor creates a raw socket without opening it. The open()
    * function must be called before data can be sent or received on the socket.
    *
-   * @param io_service The io_service object that the raw socket will use
+   * @param io_context The io_context object that the raw socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    */
-  explicit basic_raw_socket(boost::asio::io_service& io_service)
-    : basic_socket<Protocol, RawSocketService>(io_service)
+  explicit basic_raw_socket(boost::asio::io_context& io_context)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context)
   {
   }
 
@@ -75,7 +79,7 @@ class basic_raw_socket
   /**
    * This constructor creates and opens a raw socket.
    *
-   * @param io_service The io_service object that the raw socket will use
+   * @param io_context The io_context object that the raw socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    *
@@ -83,9 +87,9 @@ class basic_raw_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_raw_socket(boost::asio::io_service& io_service,
+  basic_raw_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol)
-    : basic_socket<Protocol, RawSocketService>(io_service, protocol)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, protocol)
   {
   }
 
@@ -96,7 +100,7 @@ class basic_raw_socket
    * to the specified endpoint on the local machine. The protocol used is the
    * protocol associated with the given endpoint.
    *
-   * @param io_service The io_service object that the raw socket will use
+   * @param io_context The io_context object that the raw socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    *
@@ -105,9 +109,9 @@ class basic_raw_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_raw_socket(boost::asio::io_service& io_service,
+  basic_raw_socket(boost::asio::io_context& io_context,
       const endpoint_type& endpoint)
-    : basic_socket<Protocol, RawSocketService>(io_service, endpoint)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, endpoint)
   {
   }
 
@@ -116,7 +120,7 @@ class basic_raw_socket
    * This constructor creates a raw socket object to hold an existing
    * native socket.
    *
-   * @param io_service The io_service object that the raw socket will use
+   * @param io_context The io_context object that the raw socket will use
    * to dispatch handlers for any asynchronous operations performed on the
    * socket.
    *
@@ -126,10 +130,10 @@ class basic_raw_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_raw_socket(boost::asio::io_service& io_service,
+  basic_raw_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol, const native_handle_type& native_socket)
-    : basic_socket<Protocol, RawSocketService>(
-        io_service, protocol, native_socket)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(
+        io_context, protocol, native_socket)
   {
   }
 
@@ -142,11 +146,10 @@ class basic_raw_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_raw_socket(io_service&) constructor.
+   * constructed using the @c basic_raw_socket(io_context&) constructor.
    */
   basic_raw_socket(basic_raw_socket&& other)
-    : basic_socket<Protocol, RawSocketService>(
-        BOOST_ASIO_MOVE_CAST(basic_raw_socket)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -158,12 +161,11 @@ class basic_raw_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_raw_socket(io_service&) constructor.
+   * constructed using the @c basic_raw_socket(io_context&) constructor.
    */
   basic_raw_socket& operator=(basic_raw_socket&& other)
   {
-    basic_socket<Protocol, RawSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_raw_socket)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 
@@ -175,14 +177,12 @@ class basic_raw_socket
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_raw_socket(io_service&) constructor.
+   * constructed using the @c basic_raw_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename RawSocketService1>
-  basic_raw_socket(basic_raw_socket<Protocol1, RawSocketService1>&& other,
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
+  basic_raw_socket(basic_raw_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other,
       typename enable_if<is_convertible<Protocol1, Protocol>::value>::type* = 0)
-    : basic_socket<Protocol, RawSocketService>(
-        BOOST_ASIO_MOVE_CAST2(basic_raw_socket<
-          Protocol1, RawSocketService1>)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -194,20 +194,27 @@ class basic_raw_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_raw_socket(io_service&) constructor.
+   * constructed using the @c basic_raw_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename RawSocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   typename enable_if<is_convertible<Protocol1, Protocol>::value,
       basic_raw_socket>::type& operator=(
-        basic_raw_socket<Protocol1, RawSocketService1>&& other)
+        basic_raw_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other)
   {
-    basic_socket<Protocol, RawSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST2(basic_raw_socket<
-          Protocol1, RawSocketService1>)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
+  /// Destroys the socket.
+  /**
+   * This function destroys the socket, cancelling any outstanding asynchronous
+   * operations associated with the socket as if by calling @c cancel.
+   */
+  ~basic_raw_socket()
+  {
+  }
+
   /// Send some data on a connected socket.
   /**
    * This function is used to send data on the raw socket. The function call
@@ -310,7 +317,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_send operation can only be used with a connected socket.
    * Use the async_send_to function to send data on an unconnected raw
@@ -335,8 +342,18 @@ class basic_raw_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(this->get_implementation(),
         buffers, 0, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(this->get_implementation(),
+        buffers, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous send on a connected socket.
@@ -361,7 +378,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_send operation can only be used with a connected socket.
    * Use the async_send_to function to send data on an unconnected raw
@@ -378,8 +395,18 @@ class basic_raw_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(this->get_implementation(),
         buffers, flags, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(this->get_implementation(),
+        buffers, flags, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Send raw data to the specified endpoint.
@@ -493,7 +520,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * To send a single data buffer use the @ref buffer function as follows:
@@ -518,8 +545,18 @@ class basic_raw_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send_to(this->get_implementation(),
         buffers, destination, 0, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send_to(this->get_implementation(),
+        buffers, destination, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous send.
@@ -547,7 +584,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename ConstBufferSequence, typename WriteHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
@@ -560,9 +597,20 @@ class basic_raw_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send_to(
         this->get_implementation(), buffers, destination, flags,
         BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send_to(
+        this->get_implementation(), buffers, destination, flags,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Receive some data on a connected socket.
@@ -674,7 +722,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_receive operation can only be used with a connected socket.
    * Use the async_receive_from function to receive data on an unconnected
@@ -700,8 +748,18 @@ class basic_raw_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(this->get_implementation(),
         buffers, 0, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive(this->get_implementation(),
+        buffers, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous receive on a connected socket.
@@ -726,7 +784,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The async_receive operation can only be used with a connected socket.
    * Use the async_receive_from function to receive data on an unconnected
@@ -743,8 +801,18 @@ class basic_raw_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(this->get_implementation(),
         buffers, flags, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive(this->get_implementation(),
+        buffers, flags, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Receive raw data with the endpoint of the sender.
@@ -861,7 +929,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * To receive into a single data buffer use the @ref buffer function as
@@ -883,9 +951,20 @@ class basic_raw_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive_from(
         this->get_implementation(), buffers, sender_endpoint, 0,
         BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive_from(
+        this->get_implementation(), buffers, sender_endpoint, 0,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous receive.
@@ -915,7 +994,7 @@ class basic_raw_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename MutableBufferSequence, typename ReadHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
@@ -928,9 +1007,20 @@ class basic_raw_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive_from(
         this->get_implementation(), buffers, sender_endpoint, flags,
         BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive_from(
+        this->get_implementation(), buffers, sender_endpoint, flags,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 };
 
diff --git a/include/boost/asio/basic_seq_packet_socket.hpp b/include/boost/asio/basic_seq_packet_socket.hpp
index c8e43f77d6..a48a5b847e 100644
--- a/include/boost/asio/basic_seq_packet_socket.hpp
+++ b/include/boost/asio/basic_seq_packet_socket.hpp
@@ -21,7 +21,10 @@
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/seq_packet_socket_service.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/seq_packet_socket_service.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -37,19 +40,19 @@ namespace asio {
  * @e Distinct @e objects: Safe.@n
  * @e Shared @e objects: Unsafe.
  */
-template <typename Protocol,
-    typename SeqPacketSocketService = seq_packet_socket_service<Protocol> >
+template <typename Protocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= seq_packet_socket_service<Protocol>)>
 class basic_seq_packet_socket
-  : public basic_socket<Protocol, SeqPacketSocketService>
+  : public basic_socket<Protocol BOOST_ASIO_SVC_TARG>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// socket.
-  typedef typename SeqPacketSocketService::native_handle_type native_type;
-
   /// The native representation of a socket.
-  typedef typename SeqPacketSocketService::native_handle_type
-    native_handle_type;
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef typename basic_socket<
+    Protocol BOOST_ASIO_SVC_TARG>::native_handle_type native_handle_type;
+#endif
 
   /// The protocol type.
   typedef Protocol protocol_type;
@@ -63,12 +66,12 @@ class basic_seq_packet_socket
    * socket needs to be opened and then connected or accepted before data can
    * be sent or received on it.
    *
-   * @param io_service The io_service object that the sequenced packet socket
+   * @param io_context The io_context object that the sequenced packet socket
    * will use to dispatch handlers for any asynchronous operations performed on
    * the socket.
    */
-  explicit basic_seq_packet_socket(boost::asio::io_service& io_service)
-    : basic_socket<Protocol, SeqPacketSocketService>(io_service)
+  explicit basic_seq_packet_socket(boost::asio::io_context& io_context)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context)
   {
   }
 
@@ -78,7 +81,7 @@ class basic_seq_packet_socket
    * needs to be connected or accepted before data can be sent or received on
    * it.
    *
-   * @param io_service The io_service object that the sequenced packet socket
+   * @param io_context The io_context object that the sequenced packet socket
    * will use to dispatch handlers for any asynchronous operations performed on
    * the socket.
    *
@@ -86,9 +89,9 @@ class basic_seq_packet_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_seq_packet_socket(boost::asio::io_service& io_service,
+  basic_seq_packet_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol)
-    : basic_socket<Protocol, SeqPacketSocketService>(io_service, protocol)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, protocol)
   {
   }
 
@@ -99,7 +102,7 @@ class basic_seq_packet_socket
    * it bound to the specified endpoint on the local machine. The protocol used
    * is the protocol associated with the given endpoint.
    *
-   * @param io_service The io_service object that the sequenced packet socket
+   * @param io_context The io_context object that the sequenced packet socket
    * will use to dispatch handlers for any asynchronous operations performed on
    * the socket.
    *
@@ -108,9 +111,9 @@ class basic_seq_packet_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_seq_packet_socket(boost::asio::io_service& io_service,
+  basic_seq_packet_socket(boost::asio::io_context& io_context,
       const endpoint_type& endpoint)
-    : basic_socket<Protocol, SeqPacketSocketService>(io_service, endpoint)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, endpoint)
   {
   }
 
@@ -119,7 +122,7 @@ class basic_seq_packet_socket
    * This constructor creates a sequenced packet socket object to hold an
    * existing native socket.
    *
-   * @param io_service The io_service object that the sequenced packet socket
+   * @param io_context The io_context object that the sequenced packet socket
    * will use to dispatch handlers for any asynchronous operations performed on
    * the socket.
    *
@@ -129,10 +132,10 @@ class basic_seq_packet_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_seq_packet_socket(boost::asio::io_service& io_service,
+  basic_seq_packet_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol, const native_handle_type& native_socket)
-    : basic_socket<Protocol, SeqPacketSocketService>(
-        io_service, protocol, native_socket)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(
+        io_context, protocol, native_socket)
   {
   }
 
@@ -146,11 +149,10 @@ class basic_seq_packet_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_seq_packet_socket(io_service&) constructor.
+   * constructed using the @c basic_seq_packet_socket(io_context&) constructor.
    */
   basic_seq_packet_socket(basic_seq_packet_socket&& other)
-    : basic_socket<Protocol, SeqPacketSocketService>(
-        BOOST_ASIO_MOVE_CAST(basic_seq_packet_socket)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -163,12 +165,11 @@ class basic_seq_packet_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_seq_packet_socket(io_service&) constructor.
+   * constructed using the @c basic_seq_packet_socket(io_context&) constructor.
    */
   basic_seq_packet_socket& operator=(basic_seq_packet_socket&& other)
   {
-    basic_socket<Protocol, SeqPacketSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_seq_packet_socket)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 
@@ -182,15 +183,13 @@ class basic_seq_packet_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_seq_packet_socket(io_service&) constructor.
+   * constructed using the @c basic_seq_packet_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename SeqPacketSocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   basic_seq_packet_socket(
-      basic_seq_packet_socket<Protocol1, SeqPacketSocketService1>&& other,
+      basic_seq_packet_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other,
       typename enable_if<is_convertible<Protocol1, Protocol>::value>::type* = 0)
-    : basic_socket<Protocol, SeqPacketSocketService>(
-        BOOST_ASIO_MOVE_CAST2(basic_seq_packet_socket<
-          Protocol1, SeqPacketSocketService1>)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -204,20 +203,27 @@ class basic_seq_packet_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_seq_packet_socket(io_service&) constructor.
+   * constructed using the @c basic_seq_packet_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename SeqPacketSocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   typename enable_if<is_convertible<Protocol1, Protocol>::value,
       basic_seq_packet_socket>::type& operator=(
-        basic_seq_packet_socket<Protocol1, SeqPacketSocketService1>&& other)
+        basic_seq_packet_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other)
   {
-    basic_socket<Protocol, SeqPacketSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST2(basic_seq_packet_socket<
-          Protocol1, SeqPacketSocketService1>)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
+  /// Destroys the socket.
+  /**
+   * This function destroys the socket, cancelling any outstanding asynchronous
+   * operations associated with the socket as if by calling @c cancel.
+   */
+  ~basic_seq_packet_socket()
+  {
+  }
+
   /// Send some data on the socket.
   /**
    * This function is used to send data on the sequenced packet socket. The
@@ -300,7 +306,7 @@ class basic_seq_packet_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * To send a single data buffer use the @ref buffer function as follows:
@@ -322,8 +328,18 @@ class basic_seq_packet_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(this->get_implementation(),
         buffers, flags, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(this->get_implementation(),
+        buffers, flags, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Receive some data on the socket.
@@ -360,8 +376,13 @@ class basic_seq_packet_socket
       socket_base::message_flags& out_flags)
   {
     boost::system::error_code ec;
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     std::size_t s = this->get_service().receive(
         this->get_implementation(), buffers, 0, out_flags, ec);
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    std::size_t s = this->get_service().receive_with_flags(
+        this->get_implementation(), buffers, 0, out_flags, ec);
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     boost::asio::detail::throw_error(ec, "receive");
     return s;
   }
@@ -407,8 +428,13 @@ class basic_seq_packet_socket
       socket_base::message_flags& out_flags)
   {
     boost::system::error_code ec;
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     std::size_t s = this->get_service().receive(
         this->get_implementation(), buffers, in_flags, out_flags, ec);
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    std::size_t s = this->get_service().receive_with_flags(
+        this->get_implementation(), buffers, in_flags, out_flags, ec);
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     boost::asio::detail::throw_error(ec, "receive");
     return s;
   }
@@ -441,8 +467,13 @@ class basic_seq_packet_socket
       socket_base::message_flags in_flags,
       socket_base::message_flags& out_flags, boost::system::error_code& ec)
   {
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().receive(this->get_implementation(),
         buffers, in_flags, out_flags, ec);
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().receive_with_flags(this->get_implementation(),
+        buffers, in_flags, out_flags, ec);
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous receive.
@@ -471,7 +502,7 @@ class basic_seq_packet_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * To receive into a single data buffer use the @ref buffer function as
@@ -494,9 +525,20 @@ class basic_seq_packet_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(
         this->get_implementation(), buffers, 0, out_flags,
         BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive_with_flags(
+        this->get_implementation(), buffers, 0, out_flags,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous receive.
@@ -527,7 +569,7 @@ class basic_seq_packet_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * To receive into a single data buffer use the @ref buffer function as
@@ -553,9 +595,20 @@ class basic_seq_packet_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(
         this->get_implementation(), buffers, in_flags, out_flags,
         BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive_with_flags(
+        this->get_implementation(), buffers, in_flags, out_flags,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 };
 
diff --git a/include/boost/asio/basic_serial_port.hpp b/include/boost/asio/basic_serial_port.hpp
index bfc78afaf6..af2193f7cb 100644
--- a/include/boost/asio/basic_serial_port.hpp
+++ b/include/boost/asio/basic_serial_port.hpp
@@ -18,6 +18,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_SERIAL_PORT) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -49,10 +51,6 @@ class basic_serial_port
     public serial_port_base
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// serial port.
-  typedef typename SerialPortService::native_handle_type native_type;
-
   /// The native representation of a serial port.
   typedef typename SerialPortService::native_handle_type native_handle_type;
 
@@ -63,11 +61,11 @@ class basic_serial_port
   /**
    * This constructor creates a serial port without opening it.
    *
-   * @param io_service The io_service object that the serial port will use to
+   * @param io_context The io_context object that the serial port will use to
    * dispatch handlers for any asynchronous operations performed on the port.
    */
-  explicit basic_serial_port(boost::asio::io_service& io_service)
-    : basic_io_object<SerialPortService>(io_service)
+  explicit basic_serial_port(boost::asio::io_context& io_context)
+    : basic_io_object<SerialPortService>(io_context)
   {
   }
 
@@ -76,15 +74,15 @@ class basic_serial_port
    * This constructor creates and opens a serial port for the specified device
    * name.
    *
-   * @param io_service The io_service object that the serial port will use to
+   * @param io_context The io_context object that the serial port will use to
    * dispatch handlers for any asynchronous operations performed on the port.
    *
    * @param device The platform-specific device name for this serial
    * port.
    */
-  explicit basic_serial_port(boost::asio::io_service& io_service,
+  explicit basic_serial_port(boost::asio::io_context& io_context,
       const char* device)
-    : basic_io_object<SerialPortService>(io_service)
+    : basic_io_object<SerialPortService>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().open(this->get_implementation(), device, ec);
@@ -96,15 +94,15 @@ class basic_serial_port
    * This constructor creates and opens a serial port for the specified device
    * name.
    *
-   * @param io_service The io_service object that the serial port will use to
+   * @param io_context The io_context object that the serial port will use to
    * dispatch handlers for any asynchronous operations performed on the port.
    *
    * @param device The platform-specific device name for this serial
    * port.
    */
-  explicit basic_serial_port(boost::asio::io_service& io_service,
+  explicit basic_serial_port(boost::asio::io_context& io_context,
       const std::string& device)
-    : basic_io_object<SerialPortService>(io_service)
+    : basic_io_object<SerialPortService>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().open(this->get_implementation(), device, ec);
@@ -116,16 +114,16 @@ class basic_serial_port
    * This constructor creates a serial port object to hold an existing native
    * serial port.
    *
-   * @param io_service The io_service object that the serial port will use to
+   * @param io_context The io_context object that the serial port will use to
    * dispatch handlers for any asynchronous operations performed on the port.
    *
    * @param native_serial_port A native serial port.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_serial_port(boost::asio::io_service& io_service,
+  basic_serial_port(boost::asio::io_context& io_context,
       const native_handle_type& native_serial_port)
-    : basic_io_object<SerialPortService>(io_service)
+    : basic_io_object<SerialPortService>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().assign(this->get_implementation(),
@@ -142,7 +140,7 @@ class basic_serial_port
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_serial_port(io_service&) constructor.
+   * constructed using the @c basic_serial_port(io_context&) constructor.
    */
   basic_serial_port(basic_serial_port&& other)
     : basic_io_object<SerialPortService>(
@@ -158,7 +156,7 @@ class basic_serial_port
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_serial_port(io_service&) constructor.
+   * constructed using the @c basic_serial_port(io_context&) constructor.
    */
   basic_serial_port& operator=(basic_serial_port&& other)
   {
@@ -220,10 +218,11 @@ class basic_serial_port
    *
    * @param ec Set the indicate what error occurred, if any.
    */
-  boost::system::error_code open(const std::string& device,
+  BOOST_ASIO_SYNC_OP_VOID open(const std::string& device,
       boost::system::error_code& ec)
   {
-    return this->get_service().open(this->get_implementation(), device, ec);
+    this->get_service().open(this->get_implementation(), device, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native serial port to the serial port.
@@ -250,11 +249,12 @@ class basic_serial_port
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code assign(const native_handle_type& native_serial_port,
+  BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& native_serial_port,
       boost::system::error_code& ec)
   {
-    return this->get_service().assign(this->get_implementation(),
+    this->get_service().assign(this->get_implementation(),
         native_serial_port, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the serial port is open.
@@ -286,21 +286,10 @@ class basic_serial_port
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code close(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return this->get_service().close(this->get_implementation(), ec);
-  }
-
-  /// (Deprecated: Use native_handle().) Get the native serial port
-  /// representation.
-  /**
-   * This function may be used to obtain the underlying representation of the
-   * serial port. This is intended to allow access to native serial port
-   * functionality that is not otherwise provided.
-   */
-  native_type native()
-  {
-    return this->get_service().native_handle(this->get_implementation());
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native serial port representation.
@@ -337,9 +326,10 @@ class basic_serial_port
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code cancel(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
-    return this->get_service().cancel(this->get_implementation(), ec);
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Send a break sequence to the serial port.
@@ -363,9 +353,10 @@ class basic_serial_port
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code send_break(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID send_break(boost::system::error_code& ec)
   {
-    return this->get_service().send_break(this->get_implementation(), ec);
+    this->get_service().send_break(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Set an option on the serial port.
@@ -407,11 +398,11 @@ class basic_serial_port
    * boost::asio::serial_port_base::character_size
    */
   template <typename SettableSerialPortOption>
-  boost::system::error_code set_option(const SettableSerialPortOption& option,
+  BOOST_ASIO_SYNC_OP_VOID set_option(const SettableSerialPortOption& option,
       boost::system::error_code& ec)
   {
-    return this->get_service().set_option(
-        this->get_implementation(), option, ec);
+    this->get_service().set_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get an option from the serial port.
@@ -455,11 +446,11 @@ class basic_serial_port
    * boost::asio::serial_port_base::character_size
    */
   template <typename GettableSerialPortOption>
-  boost::system::error_code get_option(GettableSerialPortOption& option,
+  BOOST_ASIO_SYNC_OP_VOID get_option(GettableSerialPortOption& option,
       boost::system::error_code& ec)
   {
-    return this->get_service().get_option(
-        this->get_implementation(), option, ec);
+    this->get_service().get_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Write some data to the serial port.
@@ -543,7 +534,7 @@ class basic_serial_port
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The write operation may not transmit all of the data to the peer.
    * Consider using the @ref async_write function if you need to ensure that all
@@ -655,7 +646,7 @@ class basic_serial_port
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The read operation may not read all of the requested number of bytes.
    * Consider using the @ref async_read function if you need to ensure that the
@@ -694,4 +685,6 @@ class basic_serial_port
 #endif // defined(BOOST_ASIO_HAS_SERIAL_PORT)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_BASIC_SERIAL_PORT_HPP
diff --git a/include/boost/asio/basic_signal_set.hpp b/include/boost/asio/basic_signal_set.hpp
index 608bc0a6d8..3c00fa6e26 100644
--- a/include/boost/asio/basic_signal_set.hpp
+++ b/include/boost/asio/basic_signal_set.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/basic_io_object.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/throw_error.hpp>
@@ -55,7 +57,7 @@ namespace asio {
  * ...
  *
  * // Construct a signal set registered for process termination.
- * boost::asio::signal_set signals(io_service, SIGINT, SIGTERM);
+ * boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
  *
  * // Start an asynchronous wait for one of the signals to occur.
  * signals.async_wait(handler);
@@ -99,11 +101,11 @@ class basic_signal_set
   /**
    * This constructor creates a signal set without registering for any signals.
    *
-   * @param io_service The io_service object that the signal set will use to
+   * @param io_context The io_context object that the signal set will use to
    * dispatch handlers for any asynchronous operations performed on the set.
    */
-  explicit basic_signal_set(boost::asio::io_service& io_service)
-    : basic_io_object<SignalSetService>(io_service)
+  explicit basic_signal_set(boost::asio::io_context& io_context)
+    : basic_io_object<SignalSetService>(io_context)
   {
   }
 
@@ -111,20 +113,20 @@ class basic_signal_set
   /**
    * This constructor creates a signal set and registers for one signal.
    *
-   * @param io_service The io_service object that the signal set will use to
+   * @param io_context The io_context object that the signal set will use to
    * dispatch handlers for any asynchronous operations performed on the set.
    *
    * @param signal_number_1 The signal number to be added.
    *
    * @note This constructor is equivalent to performing:
-   * @code boost::asio::signal_set signals(io_service);
+   * @code boost::asio::signal_set signals(io_context);
    * signals.add(signal_number_1); @endcode
    */
-  basic_signal_set(boost::asio::io_service& io_service, int signal_number_1)
-    : basic_io_object<SignalSetService>(io_service)
+  basic_signal_set(boost::asio::io_context& io_context, int signal_number_1)
+    : basic_io_object<SignalSetService>(io_context)
   {
     boost::system::error_code ec;
-    this->service.add(this->implementation, signal_number_1, ec);
+    this->get_service().add(this->get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
@@ -132,7 +134,7 @@ class basic_signal_set
   /**
    * This constructor creates a signal set and registers for two signals.
    *
-   * @param io_service The io_service object that the signal set will use to
+   * @param io_context The io_context object that the signal set will use to
    * dispatch handlers for any asynchronous operations performed on the set.
    *
    * @param signal_number_1 The first signal number to be added.
@@ -140,18 +142,18 @@ class basic_signal_set
    * @param signal_number_2 The second signal number to be added.
    *
    * @note This constructor is equivalent to performing:
-   * @code boost::asio::signal_set signals(io_service);
+   * @code boost::asio::signal_set signals(io_context);
    * signals.add(signal_number_1);
    * signals.add(signal_number_2); @endcode
    */
-  basic_signal_set(boost::asio::io_service& io_service, int signal_number_1,
+  basic_signal_set(boost::asio::io_context& io_context, int signal_number_1,
       int signal_number_2)
-    : basic_io_object<SignalSetService>(io_service)
+    : basic_io_object<SignalSetService>(io_context)
   {
     boost::system::error_code ec;
-    this->service.add(this->implementation, signal_number_1, ec);
+    this->get_service().add(this->get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
-    this->service.add(this->implementation, signal_number_2, ec);
+    this->get_service().add(this->get_implementation(), signal_number_2, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
@@ -159,7 +161,7 @@ class basic_signal_set
   /**
    * This constructor creates a signal set and registers for three signals.
    *
-   * @param io_service The io_service object that the signal set will use to
+   * @param io_context The io_context object that the signal set will use to
    * dispatch handlers for any asynchronous operations performed on the set.
    *
    * @param signal_number_1 The first signal number to be added.
@@ -169,21 +171,21 @@ class basic_signal_set
    * @param signal_number_3 The third signal number to be added.
    *
    * @note This constructor is equivalent to performing:
-   * @code boost::asio::signal_set signals(io_service);
+   * @code boost::asio::signal_set signals(io_context);
    * signals.add(signal_number_1);
    * signals.add(signal_number_2);
    * signals.add(signal_number_3); @endcode
    */
-  basic_signal_set(boost::asio::io_service& io_service, int signal_number_1,
+  basic_signal_set(boost::asio::io_context& io_context, int signal_number_1,
       int signal_number_2, int signal_number_3)
-    : basic_io_object<SignalSetService>(io_service)
+    : basic_io_object<SignalSetService>(io_context)
   {
     boost::system::error_code ec;
-    this->service.add(this->implementation, signal_number_1, ec);
+    this->get_service().add(this->get_implementation(), signal_number_1, ec);
     boost::asio::detail::throw_error(ec, "add");
-    this->service.add(this->implementation, signal_number_2, ec);
+    this->get_service().add(this->get_implementation(), signal_number_2, ec);
     boost::asio::detail::throw_error(ec, "add");
-    this->service.add(this->implementation, signal_number_3, ec);
+    this->get_service().add(this->get_implementation(), signal_number_3, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
@@ -199,7 +201,7 @@ class basic_signal_set
   void add(int signal_number)
   {
     boost::system::error_code ec;
-    this->service.add(this->implementation, signal_number, ec);
+    this->get_service().add(this->get_implementation(), signal_number, ec);
     boost::asio::detail::throw_error(ec, "add");
   }
 
@@ -212,10 +214,10 @@ class basic_signal_set
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code add(int signal_number,
-      boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID add(int signal_number, boost::system::error_code& ec)
   {
-    return this->service.add(this->implementation, signal_number, ec);
+    this->get_service().add(this->get_implementation(), signal_number, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Remove a signal from a signal_set.
@@ -233,7 +235,7 @@ class basic_signal_set
   void remove(int signal_number)
   {
     boost::system::error_code ec;
-    this->service.remove(this->implementation, signal_number, ec);
+    this->get_service().remove(this->get_implementation(), signal_number, ec);
     boost::asio::detail::throw_error(ec, "remove");
   }
 
@@ -249,10 +251,11 @@ class basic_signal_set
    * @note Removes any notifications that have been queued for the specified
    * signal number.
    */
-  boost::system::error_code remove(int signal_number,
+  BOOST_ASIO_SYNC_OP_VOID remove(int signal_number,
       boost::system::error_code& ec)
   {
-    return this->service.remove(this->implementation, signal_number, ec);
+    this->get_service().remove(this->get_implementation(), signal_number, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Remove all signals from a signal_set.
@@ -267,7 +270,7 @@ class basic_signal_set
   void clear()
   {
     boost::system::error_code ec;
-    this->service.clear(this->implementation, ec);
+    this->get_service().clear(this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "clear");
   }
 
@@ -280,9 +283,10 @@ class basic_signal_set
    *
    * @note Removes all queued notifications.
    */
-  boost::system::error_code clear(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID clear(boost::system::error_code& ec)
   {
-    return this->service.clear(this->implementation, ec);
+    this->get_service().clear(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Cancel all operations associated with the signal set.
@@ -309,7 +313,7 @@ class basic_signal_set
   void cancel()
   {
     boost::system::error_code ec;
-    this->service.cancel(this->implementation, ec);
+    this->get_service().cancel(this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "cancel");
   }
 
@@ -334,9 +338,10 @@ class basic_signal_set
    * These handlers can no longer be cancelled, and therefore are passed an
    * error code that indicates the successful completion of the wait operation.
    */
-  boost::system::error_code cancel(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
-    return this->service.cancel(this->implementation, ec);
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous operation to wait for a signal to be delivered.
@@ -362,7 +367,7 @@ class basic_signal_set
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename SignalHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(SignalHandler,
@@ -373,7 +378,7 @@ class basic_signal_set
     // not meet the documented type requirements for a SignalHandler.
     BOOST_ASIO_SIGNAL_HANDLER_CHECK(SignalHandler, handler) type_check;
 
-    return this->service.async_wait(this->implementation,
+    return this->get_service().async_wait(this->get_implementation(),
         BOOST_ASIO_MOVE_CAST(SignalHandler)(handler));
   }
 };
@@ -383,4 +388,6 @@ class basic_signal_set
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_BASIC_SIGNAL_SET_HPP
diff --git a/include/boost/asio/basic_socket.hpp b/include/boost/asio/basic_socket.hpp
index 777f6a9ce1..cf51470690 100644
--- a/include/boost/asio/basic_socket.hpp
+++ b/include/boost/asio/basic_socket.hpp
@@ -22,8 +22,26 @@
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/socket_base.hpp>
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#  include <boost/asio/detail/winrt_ssocket_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::winrt_ssocket_service<Protocol>
+# elif defined(BOOST_ASIO_HAS_IOCP)
+#  include <boost/asio/detail/win_iocp_socket_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::win_iocp_socket_service<Protocol>
+# else
+#  include <boost/asio/detail/reactive_socket_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::reactive_socket_service<Protocol>
+# endif
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -38,18 +56,21 @@ namespace asio {
  * @e Distinct @e objects: Safe.@n
  * @e Shared @e objects: Unsafe.
  */
-template <typename Protocol, typename SocketService>
+template <typename Protocol BOOST_ASIO_SVC_TPARAM>
 class basic_socket
-  : public basic_io_object<SocketService>,
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>,
     public socket_base
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// socket.
-  typedef typename SocketService::native_handle_type native_type;
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
 
   /// The native representation of a socket.
-  typedef typename SocketService::native_handle_type native_handle_type;
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef typename BOOST_ASIO_SVC_T::native_handle_type native_handle_type;
+#endif
 
   /// The protocol type.
   typedef Protocol protocol_type;
@@ -57,18 +78,20 @@ class basic_socket
   /// The endpoint type.
   typedef typename Protocol::endpoint endpoint_type;
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
   /// A basic_socket is always the lowest layer.
-  typedef basic_socket<Protocol, SocketService> lowest_layer_type;
+  typedef basic_socket<Protocol BOOST_ASIO_SVC_TARG> lowest_layer_type;
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
   /// Construct a basic_socket without opening it.
   /**
    * This constructor creates a socket without opening it.
    *
-   * @param io_service The io_service object that the socket will use to
+   * @param io_context The io_context object that the socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    */
-  explicit basic_socket(boost::asio::io_service& io_service)
-    : basic_io_object<SocketService>(io_service)
+  explicit basic_socket(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
   }
 
@@ -76,16 +99,16 @@ class basic_socket
   /**
    * This constructor creates and opens a socket.
    *
-   * @param io_service The io_service object that the socket will use to
+   * @param io_context The io_context object that the socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    *
    * @param protocol An object specifying protocol parameters to be used.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_socket(boost::asio::io_service& io_service,
+  basic_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol)
-    : basic_io_object<SocketService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().open(this->get_implementation(), protocol, ec);
@@ -99,7 +122,7 @@ class basic_socket
    * specified endpoint on the local machine. The protocol used is the protocol
    * associated with the given endpoint.
    *
-   * @param io_service The io_service object that the socket will use to
+   * @param io_context The io_context object that the socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    *
    * @param endpoint An endpoint on the local machine to which the socket will
@@ -107,9 +130,9 @@ class basic_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_socket(boost::asio::io_service& io_service,
+  basic_socket(boost::asio::io_context& io_context,
       const endpoint_type& endpoint)
-    : basic_io_object<SocketService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
     const protocol_type protocol = endpoint.protocol();
@@ -123,7 +146,7 @@ class basic_socket
   /**
    * This constructor creates a socket object to hold an existing native socket.
    *
-   * @param io_service The io_service object that the socket will use to
+   * @param io_context The io_context object that the socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    *
    * @param protocol An object specifying protocol parameters to be used.
@@ -132,9 +155,9 @@ class basic_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_socket(boost::asio::io_service& io_service,
+  basic_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol, const native_handle_type& native_socket)
-    : basic_io_object<SocketService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().assign(this->get_implementation(),
@@ -151,11 +174,10 @@ class basic_socket
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket(io_service&) constructor.
+   * constructed using the @c basic_socket(io_context&) constructor.
    */
   basic_socket(basic_socket&& other)
-    : basic_io_object<SocketService>(
-        BOOST_ASIO_MOVE_CAST(basic_socket)(other))
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
   {
   }
 
@@ -167,17 +189,16 @@ class basic_socket
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket(io_service&) constructor.
+   * constructed using the @c basic_socket(io_context&) constructor.
    */
   basic_socket& operator=(basic_socket&& other)
   {
-    basic_io_object<SocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_socket)(other));
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
     return *this;
   }
 
   // All sockets have access to each other's implementations.
-  template <typename Protocol1, typename SocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   friend class basic_socket;
 
   /// Move-construct a basic_socket from a socket of another protocol type.
@@ -188,12 +209,12 @@ class basic_socket
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket(io_service&) constructor.
+   * constructed using the @c basic_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename SocketService1>
-  basic_socket(basic_socket<Protocol1, SocketService1>&& other,
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
+  basic_socket(basic_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other,
       typename enable_if<is_convertible<Protocol1, Protocol>::value>::type* = 0)
-    : basic_io_object<SocketService>(
+    : basic_io_object<BOOST_ASIO_SVC_T>(
         other.get_service(), other.get_implementation())
   {
   }
@@ -206,21 +227,60 @@ class basic_socket
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket(io_service&) constructor.
+   * constructed using the @c basic_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename SocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   typename enable_if<is_convertible<Protocol1, Protocol>::value,
       basic_socket>::type& operator=(
-        basic_socket<Protocol1, SocketService1>&& other)
+        basic_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other)
   {
-    basic_socket tmp(BOOST_ASIO_MOVE_CAST2(basic_socket<
-            Protocol1, SocketService1>)(other));
-    basic_io_object<SocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_socket)(tmp));
+    basic_socket tmp(std::move(other));
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(tmp));
     return *this;
   }
 #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  // These functions are provided by basic_io_object<>.
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
   /// Get a reference to the lowest layer.
   /**
    * This function returns a reference to the lowest layer in a stack of
@@ -248,6 +308,7 @@ class basic_socket
   {
     return *this;
   }
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
   /// Open the socket using the specified protocol.
   /**
@@ -259,7 +320,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * socket.open(boost::asio::ip::tcp::v4());
    * @endcode
    */
@@ -280,7 +341,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * boost::system::error_code ec;
    * socket.open(boost::asio::ip::tcp::v4(), ec);
    * if (ec)
@@ -289,10 +350,11 @@ class basic_socket
    * }
    * @endcode
    */
-  boost::system::error_code open(const protocol_type& protocol,
+  BOOST_ASIO_SYNC_OP_VOID open(const protocol_type& protocol,
       boost::system::error_code& ec)
   {
-    return this->get_service().open(this->get_implementation(), protocol, ec);
+    this->get_service().open(this->get_implementation(), protocol, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native socket to the socket.
@@ -324,11 +386,12 @@ class basic_socket
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code assign(const protocol_type& protocol,
+  BOOST_ASIO_SYNC_OP_VOID assign(const protocol_type& protocol,
       const native_handle_type& native_socket, boost::system::error_code& ec)
   {
-    return this->get_service().assign(this->get_implementation(),
+    this->get_service().assign(this->get_implementation(),
         protocol, native_socket, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is open.
@@ -367,7 +430,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::system::error_code ec;
    * socket.close(ec);
@@ -380,20 +443,62 @@ class basic_socket
    * @note For portable behaviour with respect to graceful closure of a
    * connected socket, call shutdown() before closing the socket.
    */
-  boost::system::error_code close(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return this->get_service().close(this->get_implementation(), ec);
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  /// (Deprecated: Use native_handle().) Get the native socket representation.
+  /// Release ownership of the underlying native socket.
   /**
-   * This function may be used to obtain the underlying representation of the
-   * socket. This is intended to allow access to native socket functionality
-   * that is not otherwise provided.
+   * This function causes all outstanding asynchronous connect, send and receive
+   * operations to finish immediately, and the handlers for cancelled operations
+   * will be passed the boost::asio::error::operation_aborted error. Ownership
+   * of the native socket is then transferred to the caller.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note This function is unsupported on Windows versions prior to Windows
+   * 8.1, and will fail with boost::asio::error::operation_not_supported on
+   * these platforms.
+   */
+#if defined(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
+  && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
+  __declspec(deprecated("This function always fails with "
+        "operation_not_supported when used on Windows versions "
+        "prior to Windows 8.1."))
+#endif
+  native_handle_type release()
+  {
+    boost::system::error_code ec;
+    native_handle_type s = this->get_service().release(
+        this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "release");
+    return s;
+  }
+
+  /// Release ownership of the underlying native socket.
+  /**
+   * This function causes all outstanding asynchronous connect, send and receive
+   * operations to finish immediately, and the handlers for cancelled operations
+   * will be passed the boost::asio::error::operation_aborted error. Ownership
+   * of the native socket is then transferred to the caller.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @note This function is unsupported on Windows versions prior to Windows
+   * 8.1, and will fail with boost::asio::error::operation_not_supported on
+   * these platforms.
    */
-  native_type native()
+#if defined(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
+  && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
+  __declspec(deprecated("This function always fails with "
+        "operation_not_supported when used on Windows versions "
+        "prior to Windows 8.1."))
+#endif
+  native_handle_type release(boost::system::error_code& ec)
   {
-    return this->get_service().native_handle(this->get_implementation());
+    return this->get_service().release(this->get_implementation(), ec);
   }
 
   /// Get the native socket representation.
@@ -496,9 +601,10 @@ class basic_socket
         "operation_not_supported when used on Windows XP, Windows Server 2003, "
         "or earlier. Consult documentation for details."))
 #endif
-  boost::system::error_code cancel(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
-    return this->get_service().cancel(this->get_implementation(), ec);
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is at the out-of-band data mark.
@@ -580,7 +686,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * socket.open(boost::asio::ip::tcp::v4());
    * socket.bind(boost::asio::ip::tcp::endpoint(
    *       boost::asio::ip::tcp::v4(), 12345));
@@ -605,7 +711,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * socket.open(boost::asio::ip::tcp::v4());
    * boost::system::error_code ec;
    * socket.bind(boost::asio::ip::tcp::endpoint(
@@ -616,10 +722,11 @@ class basic_socket
    * }
    * @endcode
    */
-  boost::system::error_code bind(const endpoint_type& endpoint,
+  BOOST_ASIO_SYNC_OP_VOID bind(const endpoint_type& endpoint,
       boost::system::error_code& ec)
   {
-    return this->get_service().bind(this->get_implementation(), endpoint, ec);
+    this->get_service().bind(this->get_implementation(), endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Connect the socket to the specified endpoint.
@@ -639,7 +746,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * boost::asio::ip::tcp::endpoint endpoint(
    *     boost::asio::ip::address::from_string("1.2.3.4"), 12345);
    * socket.connect(endpoint);
@@ -675,7 +782,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * boost::asio::ip::tcp::endpoint endpoint(
    *     boost::asio::ip::address::from_string("1.2.3.4"), 12345);
    * boost::system::error_code ec;
@@ -686,20 +793,21 @@ class basic_socket
    * }
    * @endcode
    */
-  boost::system::error_code connect(const endpoint_type& peer_endpoint,
+  BOOST_ASIO_SYNC_OP_VOID connect(const endpoint_type& peer_endpoint,
       boost::system::error_code& ec)
   {
     if (!is_open())
     {
-      if (this->get_service().open(this->get_implementation(),
-            peer_endpoint.protocol(), ec))
+      this->get_service().open(this->get_implementation(),
+            peer_endpoint.protocol(), ec);
+      if (ec)
       {
-        return ec;
+        BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
       }
     }
 
-    return this->get_service().connect(
-        this->get_implementation(), peer_endpoint, ec);
+    this->get_service().connect(this->get_implementation(), peer_endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous connect.
@@ -723,7 +831,7 @@ class basic_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * @code
@@ -737,7 +845,7 @@ class basic_socket
    *
    * ...
    *
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * boost::asio::ip::tcp::endpoint endpoint(
    *     boost::asio::ip::address::from_string("1.2.3.4"), 12345);
    * socket.async_connect(endpoint, connect_handler);
@@ -757,24 +865,34 @@ class basic_socket
     {
       boost::system::error_code ec;
       const protocol_type protocol = peer_endpoint.protocol();
-      if (this->get_service().open(this->get_implementation(), protocol, ec))
+      this->get_service().open(this->get_implementation(), protocol, ec);
+      if (ec)
       {
-        detail::async_result_init<
-          ConnectHandler, void (boost::system::error_code)> init(
-            BOOST_ASIO_MOVE_CAST(ConnectHandler)(handler));
+        async_completion<ConnectHandler,
+          void (boost::system::error_code)> init(handler);
 
-        this->get_io_service().post(
+        boost::asio::post(this->get_executor(),
             boost::asio::detail::bind_handler(
               BOOST_ASIO_MOVE_CAST(BOOST_ASIO_HANDLER_TYPE(
                 ConnectHandler, void (boost::system::error_code)))(
-                  init.handler), ec));
+                  init.completion_handler), ec));
 
         return init.result.get();
       }
     }
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_connect(this->get_implementation(),
         peer_endpoint, BOOST_ASIO_MOVE_CAST(ConnectHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ConnectHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_connect(
+        this->get_implementation(), peer_endpoint, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Set an option on the socket.
@@ -805,7 +923,7 @@ class basic_socket
    * @par Example
    * Setting the IPPROTO_TCP/TCP_NODELAY option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::no_delay option(true);
    * socket.set_option(option);
@@ -847,7 +965,7 @@ class basic_socket
    * @par Example
    * Setting the IPPROTO_TCP/TCP_NODELAY option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::no_delay option(true);
    * boost::system::error_code ec;
@@ -859,11 +977,11 @@ class basic_socket
    * @endcode
    */
   template <typename SettableSocketOption>
-  boost::system::error_code set_option(const SettableSocketOption& option,
+  BOOST_ASIO_SYNC_OP_VOID set_option(const SettableSocketOption& option,
       boost::system::error_code& ec)
   {
-    return this->get_service().set_option(
-        this->get_implementation(), option, ec);
+    this->get_service().set_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get an option from the socket.
@@ -894,7 +1012,7 @@ class basic_socket
    * @par Example
    * Getting the value of the SOL_SOCKET/SO_KEEPALIVE option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::socket::keep_alive option;
    * socket.get_option(option);
@@ -937,7 +1055,7 @@ class basic_socket
    * @par Example
    * Getting the value of the SOL_SOCKET/SO_KEEPALIVE option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::socket::keep_alive option;
    * boost::system::error_code ec;
@@ -950,11 +1068,11 @@ class basic_socket
    * @endcode
    */
   template <typename GettableSocketOption>
-  boost::system::error_code get_option(GettableSocketOption& option,
+  BOOST_ASIO_SYNC_OP_VOID get_option(GettableSocketOption& option,
       boost::system::error_code& ec) const
   {
-    return this->get_service().get_option(
-        this->get_implementation(), option, ec);
+    this->get_service().get_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the socket.
@@ -972,7 +1090,7 @@ class basic_socket
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::socket::bytes_readable command;
    * socket.io_control(command);
@@ -1002,7 +1120,7 @@ class basic_socket
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::socket::bytes_readable command;
    * boost::system::error_code ec;
@@ -1015,11 +1133,11 @@ class basic_socket
    * @endcode
    */
   template <typename IoControlCommand>
-  boost::system::error_code io_control(IoControlCommand& command,
+  BOOST_ASIO_SYNC_OP_VOID io_control(IoControlCommand& command,
       boost::system::error_code& ec)
   {
-    return this->get_service().io_control(
-        this->get_implementation(), command, ec);
+    this->get_service().io_control(this->get_implementation(), command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the socket.
@@ -1071,11 +1189,11 @@ class basic_socket
    * operations. Asynchronous operations will never fail with the error
    * boost::asio::error::would_block.
    */
-  boost::system::error_code non_blocking(
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(
       bool mode, boost::system::error_code& ec)
   {
-    return this->get_service().non_blocking(
-        this->get_implementation(), mode, ec);
+    this->get_service().non_blocking(this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native socket implementation.
@@ -1135,7 +1253,7 @@ class basic_socket
    *             || ec == boost::asio::error::try_again)
    *         {
    *           // We have to wait for the socket to become ready again.
-   *           sock_.async_write_some(boost::asio::null_buffers(), *this);
+   *           sock_.async_wait(tcp::socket::wait_write, *this);
    *           return;
    *         }
    *
@@ -1159,7 +1277,7 @@ class basic_socket
    * void async_sendfile(tcp::socket& sock, int fd, Handler h)
    * {
    *   sendfile_op<Handler> op = { sock, fd, h, 0, 0 };
-   *   sock.async_write_some(boost::asio::null_buffers(), op);
+   *   sock.async_wait(tcp::socket::wait_write, op);
    * } @endcode
    */
   bool native_non_blocking() const
@@ -1225,7 +1343,7 @@ class basic_socket
    *             || ec == boost::asio::error::try_again)
    *         {
    *           // We have to wait for the socket to become ready again.
-   *           sock_.async_write_some(boost::asio::null_buffers(), *this);
+   *           sock_.async_wait(tcp::socket::wait_write, *this);
    *           return;
    *         }
    *
@@ -1249,7 +1367,7 @@ class basic_socket
    * void async_sendfile(tcp::socket& sock, int fd, Handler h)
    * {
    *   sendfile_op<Handler> op = { sock, fd, h, 0, 0 };
-   *   sock.async_write_some(boost::asio::null_buffers(), op);
+   *   sock.async_wait(tcp::socket::wait_write, op);
    * } @endcode
    */
   void native_non_blocking(bool mode)
@@ -1318,7 +1436,7 @@ class basic_socket
    *             || ec == boost::asio::error::try_again)
    *         {
    *           // We have to wait for the socket to become ready again.
-   *           sock_.async_write_some(boost::asio::null_buffers(), *this);
+   *           sock_.async_wait(tcp::socket::wait_write, *this);
    *           return;
    *         }
    *
@@ -1342,14 +1460,15 @@ class basic_socket
    * void async_sendfile(tcp::socket& sock, int fd, Handler h)
    * {
    *   sendfile_op<Handler> op = { sock, fd, h, 0, 0 };
-   *   sock.async_write_some(boost::asio::null_buffers(), op);
+   *   sock.async_wait(tcp::socket::wait_write, op);
    * } @endcode
    */
-  boost::system::error_code native_non_blocking(
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(
       bool mode, boost::system::error_code& ec)
   {
-    return this->get_service().native_non_blocking(
+    this->get_service().native_non_blocking(
         this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the local endpoint of the socket.
@@ -1362,7 +1481,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::endpoint endpoint = socket.local_endpoint();
    * @endcode
@@ -1387,7 +1506,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::system::error_code ec;
    * boost::asio::ip::tcp::endpoint endpoint = socket.local_endpoint(ec);
@@ -1412,7 +1531,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::asio::ip::tcp::endpoint endpoint = socket.remote_endpoint();
    * @endcode
@@ -1437,7 +1556,7 @@ class basic_socket
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::system::error_code ec;
    * boost::asio::ip::tcp::endpoint endpoint = socket.remote_endpoint(ec);
@@ -1464,7 +1583,7 @@ class basic_socket
    * @par Example
    * Shutting down the send side of the socket:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * socket.shutdown(boost::asio::ip::tcp::socket::shutdown_send);
    * @endcode
@@ -1488,7 +1607,7 @@ class basic_socket
    * @par Example
    * Shutting down the send side of the socket:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * ...
    * boost::system::error_code ec;
    * socket.shutdown(boost::asio::ip::tcp::socket::shutdown_send, ec);
@@ -1498,17 +1617,134 @@ class basic_socket
    * }
    * @endcode
    */
-  boost::system::error_code shutdown(shutdown_type what,
+  BOOST_ASIO_SYNC_OP_VOID shutdown(shutdown_type what,
       boost::system::error_code& ec)
   {
-    return this->get_service().shutdown(this->get_implementation(), what, ec);
+    this->get_service().shutdown(this->get_implementation(), what, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the socket to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for a socket to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired socket state.
+   *
+   * @par Example
+   * Waiting for a socket to become readable.
+   * @code
+   * boost::asio::ip::tcp::socket socket(io_context);
+   * ...
+   * socket.wait(boost::asio::ip::tcp::socket::wait_read);
+   * @endcode
+   */
+  void wait(wait_type w)
+  {
+    boost::system::error_code ec;
+    this->get_service().wait(this->get_implementation(), w, ec);
+    boost::asio::detail::throw_error(ec, "wait");
+  }
+
+  /// Wait for the socket to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for a socket to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired socket state.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @par Example
+   * Waiting for a socket to become readable.
+   * @code
+   * boost::asio::ip::tcp::socket socket(io_context);
+   * ...
+   * boost::system::error_code ec;
+   * socket.wait(boost::asio::ip::tcp::socket::wait_read, ec);
+   * @endcode
+   */
+  BOOST_ASIO_SYNC_OP_VOID wait(wait_type w, boost::system::error_code& ec)
+  {
+    this->get_service().wait(this->get_implementation(), w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the socket to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  /**
+   * This function is used to perform an asynchronous wait for a socket to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired socket state.
+   *
+   * @param handler The handler to be called when the wait operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error // Result of operation
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void wait_handler(const boost::system::error_code& error)
+   * {
+   *   if (!error)
+   *   {
+   *     // Wait succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::ip::tcp::socket socket(io_context);
+   * ...
+   * socket.async_wait(boost::asio::ip::tcp::socket::wait_read, wait_handler);
+   * @endcode
+   */
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(wait_type w, BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WaitHandler.
+    BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_wait(this->get_implementation(),
+        w, BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_wait(this->get_implementation(),
+        w, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
 protected:
   /// Protected destructor to prevent deletion through this type.
+  /**
+   * This function destroys the socket, cancelling any outstanding asynchronous
+   * operations associated with the socket as if by calling @c cancel.
+   */
   ~basic_socket()
   {
   }
+
+private:
+  // Disallow copying and assignment.
+  basic_socket(const basic_socket&) BOOST_ASIO_DELETED;
+  basic_socket& operator=(const basic_socket&) BOOST_ASIO_DELETED;
 };
 
 } // namespace asio
@@ -1516,4 +1752,8 @@ class basic_socket
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# undef BOOST_ASIO_SVC_T
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_BASIC_SOCKET_HPP
diff --git a/include/boost/asio/basic_socket_acceptor.hpp b/include/boost/asio/basic_socket_acceptor.hpp
index f1d2b8e7a6..3cbfa5081d 100644
--- a/include/boost/asio/basic_socket_acceptor.hpp
+++ b/include/boost/asio/basic_socket_acceptor.hpp
@@ -22,9 +22,27 @@
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/socket_acceptor_service.hpp>
 #include <boost/asio/socket_base.hpp>
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/socket_acceptor_service.hpp>
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#  include <boost/asio/detail/null_socket_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::null_socket_service<Protocol>
+# elif defined(BOOST_ASIO_HAS_IOCP)
+#  include <boost/asio/detail/win_iocp_socket_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::win_iocp_socket_service<Protocol>
+# else
+#  include <boost/asio/detail/reactive_socket_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::reactive_socket_service<Protocol>
+# endif
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -42,7 +60,7 @@ namespace asio {
  * @par Example
  * Opening a socket acceptor with the SO_REUSEADDR option enabled:
  * @code
- * boost::asio::ip::tcp::acceptor acceptor(io_service);
+ * boost::asio::ip::tcp::acceptor acceptor(io_context);
  * boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), port);
  * acceptor.open(endpoint.protocol());
  * acceptor.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
@@ -50,19 +68,22 @@ namespace asio {
  * acceptor.listen();
  * @endcode
  */
-template <typename Protocol,
-    typename SocketAcceptorService = socket_acceptor_service<Protocol> >
+template <typename Protocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= socket_acceptor_service<Protocol>)>
 class basic_socket_acceptor
-  : public basic_io_object<SocketAcceptorService>,
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>,
     public socket_base
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of an
-  /// acceptor.
-  typedef typename SocketAcceptorService::native_handle_type native_type;
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
 
   /// The native representation of an acceptor.
-  typedef typename SocketAcceptorService::native_handle_type native_handle_type;
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef typename BOOST_ASIO_SVC_T::native_handle_type native_handle_type;
+#endif
 
   /// The protocol type.
   typedef Protocol protocol_type;
@@ -76,12 +97,12 @@ class basic_socket_acceptor
    * connections. The open() function must be called before the acceptor can
    * accept new socket connections.
    *
-   * @param io_service The io_service object that the acceptor will use to
+   * @param io_context The io_context object that the acceptor will use to
    * dispatch handlers for any asynchronous operations performed on the
    * acceptor.
    */
-  explicit basic_socket_acceptor(boost::asio::io_service& io_service)
-    : basic_io_object<SocketAcceptorService>(io_service)
+  explicit basic_socket_acceptor(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
   }
 
@@ -89,7 +110,7 @@ class basic_socket_acceptor
   /**
    * This constructor creates an acceptor and automatically opens it.
    *
-   * @param io_service The io_service object that the acceptor will use to
+   * @param io_context The io_context object that the acceptor will use to
    * dispatch handlers for any asynchronous operations performed on the
    * acceptor.
    *
@@ -97,9 +118,9 @@ class basic_socket_acceptor
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_socket_acceptor(boost::asio::io_service& io_service,
+  basic_socket_acceptor(boost::asio::io_context& io_context,
       const protocol_type& protocol)
-    : basic_io_object<SocketAcceptorService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().open(this->get_implementation(), protocol, ec);
@@ -111,7 +132,7 @@ class basic_socket_acceptor
    * This constructor creates an acceptor and automatically opens it to listen
    * for new connections on the specified endpoint.
    *
-   * @param io_service The io_service object that the acceptor will use to
+   * @param io_context The io_context object that the acceptor will use to
    * dispatch handlers for any asynchronous operations performed on the
    * acceptor.
    *
@@ -125,7 +146,7 @@ class basic_socket_acceptor
    *
    * @note This constructor is equivalent to the following code:
    * @code
-   * basic_socket_acceptor<Protocol> acceptor(io_service);
+   * basic_socket_acceptor<Protocol> acceptor(io_context);
    * acceptor.open(endpoint.protocol());
    * if (reuse_addr)
    *   acceptor.set_option(socket_base::reuse_address(true));
@@ -133,9 +154,9 @@ class basic_socket_acceptor
    * acceptor.listen(listen_backlog);
    * @endcode
    */
-  basic_socket_acceptor(boost::asio::io_service& io_service,
+  basic_socket_acceptor(boost::asio::io_context& io_context,
       const endpoint_type& endpoint, bool reuse_addr = true)
-    : basic_io_object<SocketAcceptorService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
     const protocol_type protocol = endpoint.protocol();
@@ -150,7 +171,7 @@ class basic_socket_acceptor
     this->get_service().bind(this->get_implementation(), endpoint, ec);
     boost::asio::detail::throw_error(ec, "bind");
     this->get_service().listen(this->get_implementation(),
-        socket_base::max_connections, ec);
+        socket_base::max_listen_connections, ec);
     boost::asio::detail::throw_error(ec, "listen");
   }
 
@@ -159,7 +180,7 @@ class basic_socket_acceptor
    * This constructor creates an acceptor object to hold an existing native
    * acceptor.
    *
-   * @param io_service The io_service object that the acceptor will use to
+   * @param io_context The io_context object that the acceptor will use to
    * dispatch handlers for any asynchronous operations performed on the
    * acceptor.
    *
@@ -169,9 +190,9 @@ class basic_socket_acceptor
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_socket_acceptor(boost::asio::io_service& io_service,
+  basic_socket_acceptor(boost::asio::io_context& io_context,
       const protocol_type& protocol, const native_handle_type& native_acceptor)
-    : basic_io_object<SocketAcceptorService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().assign(this->get_implementation(),
@@ -188,11 +209,10 @@ class basic_socket_acceptor
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket_acceptor(io_service&) constructor.
+   * constructed using the @c basic_socket_acceptor(io_context&) constructor.
    */
   basic_socket_acceptor(basic_socket_acceptor&& other)
-    : basic_io_object<SocketAcceptorService>(
-        BOOST_ASIO_MOVE_CAST(basic_socket_acceptor)(other))
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
   {
   }
 
@@ -204,17 +224,16 @@ class basic_socket_acceptor
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket_acceptor(io_service&) constructor.
+   * constructed using the @c basic_socket_acceptor(io_context&) constructor.
    */
   basic_socket_acceptor& operator=(basic_socket_acceptor&& other)
   {
-    basic_io_object<SocketAcceptorService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_socket_acceptor)(other));
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
     return *this;
   }
 
   // All socket acceptors have access to each other's implementations.
-  template <typename Protocol1, typename SocketAcceptorService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   friend class basic_socket_acceptor;
 
   /// Move-construct a basic_socket_acceptor from an acceptor of another
@@ -226,13 +245,13 @@ class basic_socket_acceptor
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket(io_service&) constructor.
+   * constructed using the @c basic_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename SocketAcceptorService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   basic_socket_acceptor(
-      basic_socket_acceptor<Protocol1, SocketAcceptorService1>&& other,
+      basic_socket_acceptor<Protocol1 BOOST_ASIO_SVC_TARG1>&& other,
       typename enable_if<is_convertible<Protocol1, Protocol>::value>::type* = 0)
-    : basic_io_object<SocketAcceptorService>(
+    : basic_io_object<BOOST_ASIO_SVC_T>(
         other.get_service(), other.get_implementation())
   {
   }
@@ -246,21 +265,69 @@ class basic_socket_acceptor
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_socket(io_service&) constructor.
+   * constructed using the @c basic_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename SocketAcceptorService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   typename enable_if<is_convertible<Protocol1, Protocol>::value,
       basic_socket_acceptor>::type& operator=(
-        basic_socket_acceptor<Protocol1, SocketAcceptorService1>&& other)
+        basic_socket_acceptor<Protocol1 BOOST_ASIO_SVC_TARG1>&& other)
   {
-    basic_socket_acceptor tmp(BOOST_ASIO_MOVE_CAST2(basic_socket_acceptor<
-            Protocol1, SocketAcceptorService1>)(other));
-    basic_io_object<SocketAcceptorService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_socket_acceptor)(tmp));
+    basic_socket_acceptor tmp(std::move(other));
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(tmp));
     return *this;
   }
 #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
+  /// Destroys the acceptor.
+  /**
+   * This function destroys the acceptor, cancelling any outstanding
+   * asynchronous operations associated with the acceptor as if by calling
+   * @c cancel.
+   */
+  ~basic_socket_acceptor()
+  {
+  }
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  // These functions are provided by basic_io_object<>.
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
   /// Open the acceptor using the specified protocol.
   /**
    * This function opens the socket acceptor so that it will use the specified
@@ -272,7 +339,7 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * acceptor.open(boost::asio::ip::tcp::v4());
    * @endcode
    */
@@ -294,7 +361,7 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * boost::system::error_code ec;
    * acceptor.open(boost::asio::ip::tcp::v4(), ec);
    * if (ec)
@@ -303,10 +370,11 @@ class basic_socket_acceptor
    * }
    * @endcode
    */
-  boost::system::error_code open(const protocol_type& protocol,
+  BOOST_ASIO_SYNC_OP_VOID open(const protocol_type& protocol,
       boost::system::error_code& ec)
   {
-    return this->get_service().open(this->get_implementation(), protocol, ec);
+    this->get_service().open(this->get_implementation(), protocol, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assigns an existing native acceptor to the acceptor.
@@ -338,11 +406,12 @@ class basic_socket_acceptor
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code assign(const protocol_type& protocol,
+  BOOST_ASIO_SYNC_OP_VOID assign(const protocol_type& protocol,
       const native_handle_type& native_acceptor, boost::system::error_code& ec)
   {
-    return this->get_service().assign(this->get_implementation(),
+    this->get_service().assign(this->get_implementation(),
         protocol, native_acceptor, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the acceptor is open.
@@ -363,7 +432,7 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), 12345);
    * acceptor.open(endpoint.protocol());
    * acceptor.bind(endpoint);
@@ -388,7 +457,7 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * boost::asio::ip::tcp::endpoint endpoint(boost::asio::ip::tcp::v4(), 12345);
    * acceptor.open(endpoint.protocol());
    * boost::system::error_code ec;
@@ -399,10 +468,11 @@ class basic_socket_acceptor
    * }
    * @endcode
    */
-  boost::system::error_code bind(const endpoint_type& endpoint,
+  BOOST_ASIO_SYNC_OP_VOID bind(const endpoint_type& endpoint,
       boost::system::error_code& ec)
   {
-    return this->get_service().bind(this->get_implementation(), endpoint, ec);
+    this->get_service().bind(this->get_implementation(), endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Place the acceptor into the state where it will listen for new
@@ -415,7 +485,7 @@ class basic_socket_acceptor
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  void listen(int backlog = socket_base::max_connections)
+  void listen(int backlog = socket_base::max_listen_connections)
   {
     boost::system::error_code ec;
     this->get_service().listen(this->get_implementation(), backlog, ec);
@@ -434,19 +504,20 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::system::error_code ec;
-   * acceptor.listen(boost::asio::socket_base::max_connections, ec);
+   * acceptor.listen(boost::asio::socket_base::max_listen_connections, ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
-  boost::system::error_code listen(int backlog, boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID listen(int backlog, boost::system::error_code& ec)
   {
-    return this->get_service().listen(this->get_implementation(), backlog, ec);
+    this->get_service().listen(this->get_implementation(), backlog, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Close the acceptor.
@@ -478,7 +549,7 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::system::error_code ec;
    * acceptor.close(ec);
@@ -488,20 +559,62 @@ class basic_socket_acceptor
    * }
    * @endcode
    */
-  boost::system::error_code close(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return this->get_service().close(this->get_implementation(), ec);
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  /// (Deprecated: Use native_handle().) Get the native acceptor representation.
+  /// Release ownership of the underlying native acceptor.
   /**
-   * This function may be used to obtain the underlying representation of the
-   * acceptor. This is intended to allow access to native acceptor functionality
-   * that is not otherwise provided.
+   * This function causes all outstanding asynchronous accept operations to
+   * finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error. Ownership of the
+   * native acceptor is then transferred to the caller.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note This function is unsupported on Windows versions prior to Windows
+   * 8.1, and will fail with boost::asio::error::operation_not_supported on
+   * these platforms.
    */
-  native_type native()
+#if defined(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
+  && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
+  __declspec(deprecated("This function always fails with "
+        "operation_not_supported when used on Windows versions "
+        "prior to Windows 8.1."))
+#endif
+  native_handle_type release()
   {
-    return this->get_service().native_handle(this->get_implementation());
+    boost::system::error_code ec;
+    native_handle_type s = this->get_service().release(
+        this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "release");
+    return s;
+  }
+
+  /// Release ownership of the underlying native acceptor.
+  /**
+   * This function causes all outstanding asynchronous accept operations to
+   * finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error. Ownership of the
+   * native acceptor is then transferred to the caller.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @note This function is unsupported on Windows versions prior to Windows
+   * 8.1, and will fail with boost::asio::error::operation_not_supported on
+   * these platforms.
+   */
+#if defined(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
+  && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
+  __declspec(deprecated("This function always fails with "
+        "operation_not_supported when used on Windows versions "
+        "prior to Windows 8.1."))
+#endif
+  native_handle_type release(boost::system::error_code& ec)
+  {
+    return this->get_service().release(this->get_implementation(), ec);
   }
 
   /// Get the native acceptor representation.
@@ -538,9 +651,10 @@ class basic_socket_acceptor
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code cancel(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
-    return this->get_service().cancel(this->get_implementation(), ec);
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Set an option on the acceptor.
@@ -558,7 +672,7 @@ class basic_socket_acceptor
    * @par Example
    * Setting the SOL_SOCKET/SO_REUSEADDR option:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::asio::ip::tcp::acceptor::reuse_address option(true);
    * acceptor.set_option(option);
@@ -587,7 +701,7 @@ class basic_socket_acceptor
    * @par Example
    * Setting the SOL_SOCKET/SO_REUSEADDR option:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::asio::ip::tcp::acceptor::reuse_address option(true);
    * boost::system::error_code ec;
@@ -599,11 +713,11 @@ class basic_socket_acceptor
    * @endcode
    */
   template <typename SettableSocketOption>
-  boost::system::error_code set_option(const SettableSocketOption& option,
+  BOOST_ASIO_SYNC_OP_VOID set_option(const SettableSocketOption& option,
       boost::system::error_code& ec)
   {
-    return this->get_service().set_option(
-        this->get_implementation(), option, ec);
+    this->get_service().set_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get an option from the acceptor.
@@ -621,7 +735,7 @@ class basic_socket_acceptor
    * @par Example
    * Getting the value of the SOL_SOCKET/SO_REUSEADDR option:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::asio::ip::tcp::acceptor::reuse_address option;
    * acceptor.get_option(option);
@@ -651,7 +765,7 @@ class basic_socket_acceptor
    * @par Example
    * Getting the value of the SOL_SOCKET/SO_REUSEADDR option:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::asio::ip::tcp::acceptor::reuse_address option;
    * boost::system::error_code ec;
@@ -664,11 +778,11 @@ class basic_socket_acceptor
    * @endcode
    */
   template <typename GettableSocketOption>
-  boost::system::error_code get_option(GettableSocketOption& option,
+  BOOST_ASIO_SYNC_OP_VOID get_option(GettableSocketOption& option,
       boost::system::error_code& ec)
   {
-    return this->get_service().get_option(
-        this->get_implementation(), option, ec);
+    this->get_service().get_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the acceptor.
@@ -685,7 +799,7 @@ class basic_socket_acceptor
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::asio::ip::tcp::acceptor::non_blocking_io command(true);
    * socket.io_control(command);
@@ -713,7 +827,7 @@ class basic_socket_acceptor
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::asio::ip::tcp::acceptor::non_blocking_io command(true);
    * boost::system::error_code ec;
@@ -725,11 +839,11 @@ class basic_socket_acceptor
    * @endcode
    */
   template <typename IoControlCommand>
-  boost::system::error_code io_control(IoControlCommand& command,
+  BOOST_ASIO_SYNC_OP_VOID io_control(IoControlCommand& command,
       boost::system::error_code& ec)
   {
-    return this->get_service().io_control(
-        this->get_implementation(), command, ec);
+    this->get_service().io_control(this->get_implementation(), command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the acceptor.
@@ -781,11 +895,11 @@ class basic_socket_acceptor
    * operations. Asynchronous operations will never fail with the error
    * boost::asio::error::would_block.
    */
-  boost::system::error_code non_blocking(
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(
       bool mode, boost::system::error_code& ec)
   {
-    return this->get_service().non_blocking(
-        this->get_implementation(), mode, ec);
+    this->get_service().non_blocking(this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native acceptor implementation.
@@ -845,11 +959,12 @@ class basic_socket_acceptor
    * function fails with boost::asio::error::invalid_argument, as the
    * combination does not make sense.
    */
-  boost::system::error_code native_non_blocking(
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(
       bool mode, boost::system::error_code& ec)
   {
-    return this->get_service().native_non_blocking(
+    this->get_service().native_non_blocking(
         this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the local endpoint of the acceptor.
@@ -862,7 +977,7 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::asio::ip::tcp::endpoint endpoint = acceptor.local_endpoint();
    * @endcode
@@ -888,7 +1003,7 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
    * boost::system::error_code ec;
    * boost::asio::ip::tcp::endpoint endpoint = acceptor.local_endpoint(ec);
@@ -903,6 +1018,116 @@ class basic_socket_acceptor
     return this->get_service().local_endpoint(this->get_implementation(), ec);
   }
 
+  /// Wait for the acceptor to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for an acceptor to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired acceptor state.
+   *
+   * @par Example
+   * Waiting for an acceptor to become readable.
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * acceptor.wait(boost::asio::ip::tcp::acceptor::wait_read);
+   * @endcode
+   */
+  void wait(wait_type w)
+  {
+    boost::system::error_code ec;
+    this->get_service().wait(this->get_implementation(), w, ec);
+    boost::asio::detail::throw_error(ec, "wait");
+  }
+
+  /// Wait for the acceptor to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for an acceptor to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired acceptor state.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @par Example
+   * Waiting for an acceptor to become readable.
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::system::error_code ec;
+   * acceptor.wait(boost::asio::ip::tcp::acceptor::wait_read, ec);
+   * @endcode
+   */
+  BOOST_ASIO_SYNC_OP_VOID wait(wait_type w, boost::system::error_code& ec)
+  {
+    this->get_service().wait(this->get_implementation(), w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the acceptor to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  /**
+   * This function is used to perform an asynchronous wait for an acceptor to
+   * enter a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired acceptor state.
+   *
+   * @param handler The handler to be called when the wait operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error // Result of operation
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void wait_handler(const boost::system::error_code& error)
+   * {
+   *   if (!error)
+   *   {
+   *     // Wait succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * acceptor.async_wait(
+   *     boost::asio::ip::tcp::acceptor::wait_read,
+   *     wait_handler);
+   * @endcode
+   */
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(wait_type w, BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WaitHandler.
+    BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_wait(this->get_implementation(),
+        w, BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_wait(this->get_implementation(),
+        w, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
   /// Accept a new connection.
   /**
    * This function is used to accept a new connection from a peer into the
@@ -915,15 +1140,21 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * acceptor.accept(socket);
    * @endcode
    */
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   template <typename Protocol1, typename SocketService>
   void accept(basic_socket<Protocol1, SocketService>& peer,
       typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  template <typename Protocol1>
+  void accept(basic_socket<Protocol1>& peer,
+      typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   {
     boost::system::error_code ec;
     this->get_service().accept(this->get_implementation(),
@@ -943,9 +1174,9 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
-   * boost::asio::ip::tcp::soocket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * boost::system::error_code ec;
    * acceptor.accept(socket, ec);
    * if (ec)
@@ -954,14 +1185,22 @@ class basic_socket_acceptor
    * }
    * @endcode
    */
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   template <typename Protocol1, typename SocketService>
-  boost::system::error_code accept(
+  BOOST_ASIO_SYNC_OP_VOID accept(
       basic_socket<Protocol1, SocketService>& peer,
       boost::system::error_code& ec,
       typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  template <typename Protocol1>
+  BOOST_ASIO_SYNC_OP_VOID accept(
+      basic_socket<Protocol1>& peer, boost::system::error_code& ec,
+      typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   {
-    return this->get_service().accept(this->get_implementation(),
+    this->get_service().accept(this->get_implementation(),
         peer, static_cast<endpoint_type*>(0), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous accept.
@@ -982,7 +1221,7 @@ class basic_socket_acceptor
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @par Example
    * @code
@@ -996,26 +1235,45 @@ class basic_socket_acceptor
    *
    * ...
    *
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * acceptor.async_accept(socket, accept_handler);
    * @endcode
    */
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   template <typename Protocol1, typename SocketService, typename AcceptHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(AcceptHandler,
       void (boost::system::error_code))
   async_accept(basic_socket<Protocol1, SocketService>& peer,
       BOOST_ASIO_MOVE_ARG(AcceptHandler) handler,
       typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  template <typename Protocol1, typename AcceptHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(AcceptHandler,
+      void (boost::system::error_code))
+  async_accept(basic_socket<Protocol1>& peer,
+      BOOST_ASIO_MOVE_ARG(AcceptHandler) handler,
+      typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   {
     // If you get an error on the following line it means that your handler does
     // not meet the documented type requirements for a AcceptHandler.
     BOOST_ASIO_ACCEPT_HANDLER_CHECK(AcceptHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_accept(this->get_implementation(),
         peer, static_cast<endpoint_type*>(0),
         BOOST_ASIO_MOVE_CAST(AcceptHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<AcceptHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_accept(this->get_implementation(),
+        peer, static_cast<endpoint_type*>(0), init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Accept a new connection and obtain the endpoint of the peer
@@ -1034,16 +1292,20 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * boost::asio::ip::tcp::endpoint endpoint;
    * acceptor.accept(socket, endpoint);
    * @endcode
    */
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   template <typename SocketService>
   void accept(basic_socket<protocol_type, SocketService>& peer,
       endpoint_type& peer_endpoint)
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  void accept(basic_socket<protocol_type>& peer, endpoint_type& peer_endpoint)
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   {
     boost::system::error_code ec;
     this->get_service().accept(this->get_implementation(),
@@ -1067,9 +1329,9 @@ class basic_socket_acceptor
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service);
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
    * ...
-   * boost::asio::ip::tcp::socket socket(io_service);
+   * boost::asio::ip::tcp::socket socket(io_context);
    * boost::asio::ip::tcp::endpoint endpoint;
    * boost::system::error_code ec;
    * acceptor.accept(socket, endpoint, ec);
@@ -1079,13 +1341,19 @@ class basic_socket_acceptor
    * }
    * @endcode
    */
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   template <typename SocketService>
-  boost::system::error_code accept(
+  BOOST_ASIO_SYNC_OP_VOID accept(
       basic_socket<protocol_type, SocketService>& peer,
       endpoint_type& peer_endpoint, boost::system::error_code& ec)
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  BOOST_ASIO_SYNC_OP_VOID accept(basic_socket<protocol_type>& peer,
+      endpoint_type& peer_endpoint, boost::system::error_code& ec)
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   {
-    return this->get_service().accept(
+    this->get_service().accept(
         this->get_implementation(), peer, &peer_endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous accept.
@@ -1112,21 +1380,600 @@ class basic_socket_acceptor
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   template <typename SocketService, typename AcceptHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(AcceptHandler,
       void (boost::system::error_code))
   async_accept(basic_socket<protocol_type, SocketService>& peer,
       endpoint_type& peer_endpoint, BOOST_ASIO_MOVE_ARG(AcceptHandler) handler)
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  template <typename AcceptHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(AcceptHandler,
+      void (boost::system::error_code))
+  async_accept(basic_socket<protocol_type>& peer,
+      endpoint_type& peer_endpoint, BOOST_ASIO_MOVE_ARG(AcceptHandler) handler)
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   {
     // If you get an error on the following line it means that your handler does
     // not meet the documented type requirements for a AcceptHandler.
     BOOST_ASIO_ACCEPT_HANDLER_CHECK(AcceptHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_accept(this->get_implementation(), peer,
         &peer_endpoint, BOOST_ASIO_MOVE_CAST(AcceptHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<AcceptHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_accept(this->get_implementation(),
+        peer, &peer_endpoint, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @returns A socket object representing the newly accepted connection.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::socket socket(acceptor.accept());
+   * @endcode
+   */
+  typename Protocol::socket accept()
+  {
+    boost::system::error_code ec;
+    typename Protocol::socket peer(
+        this->get_service().accept(
+          this->get_implementation(), 0, 0, ec));
+    boost::asio::detail::throw_error(ec, "accept");
+    return peer;
+  }
+
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns On success, a socket object representing the newly accepted
+   * connection. On error, a socket object where is_open() is false.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::socket socket(acceptor.accept(ec));
+   * if (ec)
+   * {
+   *   // An error occurred.
+   * }
+   * @endcode
+   */
+  typename Protocol::socket accept(boost::system::error_code& ec)
+  {
+    return this->get_service().accept(this->get_implementation(), 0, 0, ec);
+  }
+
+  /// Start an asynchronous accept.
+  /**
+   * This function is used to asynchronously accept a new connection. The
+   * function call always returns immediately.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param handler The handler to be called when the accept operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   typename Protocol::socket peer // On success, the newly accepted socket.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void accept_handler(const boost::system::error_code& error,
+   *     boost::asio::ip::tcp::socket peer)
+   * {
+   *   if (!error)
+   *   {
+   *     // Accept succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * acceptor.async_accept(accept_handler);
+   * @endcode
+   */
+  template <typename MoveAcceptHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(MoveAcceptHandler,
+      void (boost::system::error_code, typename Protocol::socket))
+  async_accept(BOOST_ASIO_MOVE_ARG(MoveAcceptHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a MoveAcceptHandler.
+    BOOST_ASIO_MOVE_ACCEPT_HANDLER_CHECK(MoveAcceptHandler,
+        handler, typename Protocol::socket) type_check;
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_accept(
+        this->get_implementation(), static_cast<boost::asio::io_context*>(0),
+        static_cast<endpoint_type*>(0),
+        BOOST_ASIO_MOVE_CAST(MoveAcceptHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<MoveAcceptHandler,
+      void (boost::system::error_code,
+        typename Protocol::socket)> init(handler);
+
+    this->get_service().async_accept(
+        this->get_implementation(), static_cast<boost::asio::io_context*>(0),
+        static_cast<endpoint_type*>(0), init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param io_context The io_context object to be used for the newly accepted
+   * socket.
+   *
+   * @returns A socket object representing the newly accepted connection.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::socket socket(acceptor.accept());
+   * @endcode
+   */
+  typename Protocol::socket accept(boost::asio::io_context& io_context)
+  {
+    boost::system::error_code ec;
+    typename Protocol::socket peer(
+        this->get_service().accept(this->get_implementation(),
+          &io_context, static_cast<endpoint_type*>(0), ec));
+    boost::asio::detail::throw_error(ec, "accept");
+    return peer;
   }
+
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param io_context The io_context object to be used for the newly accepted
+   * socket.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns On success, a socket object representing the newly accepted
+   * connection. On error, a socket object where is_open() is false.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::socket socket(acceptor.accept(io_context2, ec));
+   * if (ec)
+   * {
+   *   // An error occurred.
+   * }
+   * @endcode
+   */
+  typename Protocol::socket accept(
+      boost::asio::io_context& io_context, boost::system::error_code& ec)
+  {
+    return this->get_service().accept(this->get_implementation(),
+        &io_context, static_cast<endpoint_type*>(0), ec);
+  }
+
+  /// Start an asynchronous accept.
+  /**
+   * This function is used to asynchronously accept a new connection. The
+   * function call always returns immediately.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param io_context The io_context object to be used for the newly accepted
+   * socket.
+   *
+   * @param handler The handler to be called when the accept operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   typename Protocol::socket peer // On success, the newly accepted socket.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void accept_handler(const boost::system::error_code& error,
+   *     boost::asio::ip::tcp::socket peer)
+   * {
+   *   if (!error)
+   *   {
+   *     // Accept succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * acceptor.async_accept(io_context2, accept_handler);
+   * @endcode
+   */
+  template <typename MoveAcceptHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(MoveAcceptHandler,
+      void (boost::system::error_code, typename Protocol::socket))
+  async_accept(boost::asio::io_context& io_context,
+      BOOST_ASIO_MOVE_ARG(MoveAcceptHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a MoveAcceptHandler.
+    BOOST_ASIO_MOVE_ACCEPT_HANDLER_CHECK(MoveAcceptHandler,
+        handler, typename Protocol::socket) type_check;
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_accept(this->get_implementation(),
+        &io_context, static_cast<endpoint_type*>(0),
+        BOOST_ASIO_MOVE_CAST(MoveAcceptHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<MoveAcceptHandler,
+      void (boost::system::error_code,
+        typename Protocol::socket)> init(handler);
+
+    this->get_service().async_accept(this->get_implementation(),
+        &io_context, static_cast<endpoint_type*>(0), init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param peer_endpoint An endpoint object into which the endpoint of the
+   * remote peer will be written.
+   *
+   * @returns A socket object representing the newly accepted connection.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::endpoint endpoint;
+   * boost::asio::ip::tcp::socket socket(acceptor.accept(endpoint));
+   * @endcode
+   */
+  typename Protocol::socket accept(endpoint_type& peer_endpoint)
+  {
+    boost::system::error_code ec;
+    typename Protocol::socket peer(
+        this->get_service().accept(this->get_implementation(),
+          static_cast<boost::asio::io_context*>(0), &peer_endpoint, ec));
+    boost::asio::detail::throw_error(ec, "accept");
+    return peer;
+  }
+
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param peer_endpoint An endpoint object into which the endpoint of the
+   * remote peer will be written.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns On success, a socket object representing the newly accepted
+   * connection. On error, a socket object where is_open() is false.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::endpoint endpoint;
+   * boost::asio::ip::tcp::socket socket(acceptor.accept(endpoint, ec));
+   * if (ec)
+   * {
+   *   // An error occurred.
+   * }
+   * @endcode
+   */
+  typename Protocol::socket accept(
+      endpoint_type& peer_endpoint, boost::system::error_code& ec)
+  {
+    return this->get_service().accept(this->get_implementation(),
+        static_cast<boost::asio::io_context*>(0), &peer_endpoint, ec);
+  }
+
+  /// Start an asynchronous accept.
+  /**
+   * This function is used to asynchronously accept a new connection. The
+   * function call always returns immediately.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param peer_endpoint An endpoint object into which the endpoint of the
+   * remote peer will be written. Ownership of the peer_endpoint object is
+   * retained by the caller, which must guarantee that it is valid until the
+   * handler is called.
+   *
+   * @param handler The handler to be called when the accept operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   typename Protocol::socket peer // On success, the newly accepted socket.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void accept_handler(const boost::system::error_code& error,
+   *     boost::asio::ip::tcp::socket peer)
+   * {
+   *   if (!error)
+   *   {
+   *     // Accept succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::endpoint endpoint;
+   * acceptor.async_accept(endpoint, accept_handler);
+   * @endcode
+   */
+  template <typename MoveAcceptHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(MoveAcceptHandler,
+      void (boost::system::error_code, typename Protocol::socket))
+  async_accept(endpoint_type& peer_endpoint,
+      BOOST_ASIO_MOVE_ARG(MoveAcceptHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a MoveAcceptHandler.
+    BOOST_ASIO_MOVE_ACCEPT_HANDLER_CHECK(MoveAcceptHandler,
+        handler, typename Protocol::socket) type_check;
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_accept(this->get_implementation(),
+        static_cast<boost::asio::io_context*>(0), &peer_endpoint,
+        BOOST_ASIO_MOVE_CAST(MoveAcceptHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<MoveAcceptHandler,
+      void (boost::system::error_code,
+        typename Protocol::socket)> init(handler);
+
+    this->get_service().async_accept(this->get_implementation(),
+        static_cast<boost::asio::io_context*>(0), &peer_endpoint,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param io_context The io_context object to be used for the newly accepted
+   * socket.
+   *
+   * @param peer_endpoint An endpoint object into which the endpoint of the
+   * remote peer will be written.
+   *
+   * @returns A socket object representing the newly accepted connection.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::endpoint endpoint;
+   * boost::asio::ip::tcp::socket socket(
+   *     acceptor.accept(io_context2, endpoint));
+   * @endcode
+   */
+  typename Protocol::socket accept(
+      boost::asio::io_context& io_context, endpoint_type& peer_endpoint)
+  {
+    boost::system::error_code ec;
+    typename Protocol::socket peer(
+        this->get_service().accept(this->get_implementation(),
+          &io_context, &peer_endpoint, ec));
+    boost::asio::detail::throw_error(ec, "accept");
+    return peer;
+  }
+
+  /// Accept a new connection.
+  /**
+   * This function is used to accept a new connection from a peer. The function
+   * call will block until a new connection has been accepted successfully or
+   * an error occurs.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param io_context The io_context object to be used for the newly accepted
+   * socket.
+   *
+   * @param peer_endpoint An endpoint object into which the endpoint of the
+   * remote peer will be written.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns On success, a socket object representing the newly accepted
+   * connection. On error, a socket object where is_open() is false.
+   *
+   * @par Example
+   * @code
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::endpoint endpoint;
+   * boost::asio::ip::tcp::socket socket(
+   *     acceptor.accept(io_context2, endpoint, ec));
+   * if (ec)
+   * {
+   *   // An error occurred.
+   * }
+   * @endcode
+   */
+  typename Protocol::socket accept(boost::asio::io_context& io_context,
+      endpoint_type& peer_endpoint, boost::system::error_code& ec)
+  {
+    return this->get_service().accept(this->get_implementation(),
+        &io_context, &peer_endpoint, ec);
+  }
+
+  /// Start an asynchronous accept.
+  /**
+   * This function is used to asynchronously accept a new connection. The
+   * function call always returns immediately.
+   *
+   * This overload requires that the Protocol template parameter satisfy the
+   * AcceptableProtocol type requirements.
+   *
+   * @param io_context The io_context object to be used for the newly accepted
+   * socket.
+   *
+   * @param peer_endpoint An endpoint object into which the endpoint of the
+   * remote peer will be written. Ownership of the peer_endpoint object is
+   * retained by the caller, which must guarantee that it is valid until the
+   * handler is called.
+   *
+   * @param handler The handler to be called when the accept operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   typename Protocol::socket peer // On success, the newly accepted socket.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void accept_handler(const boost::system::error_code& error,
+   *     boost::asio::ip::tcp::socket peer)
+   * {
+   *   if (!error)
+   *   {
+   *     // Accept succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::ip::tcp::acceptor acceptor(io_context);
+   * ...
+   * boost::asio::ip::tcp::endpoint endpoint;
+   * acceptor.async_accept(io_context2, endpoint, accept_handler);
+   * @endcode
+   */
+  template <typename MoveAcceptHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(MoveAcceptHandler,
+      void (boost::system::error_code, typename Protocol::socket))
+  async_accept(boost::asio::io_context& io_context,
+      endpoint_type& peer_endpoint,
+      BOOST_ASIO_MOVE_ARG(MoveAcceptHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a MoveAcceptHandler.
+    BOOST_ASIO_MOVE_ACCEPT_HANDLER_CHECK(MoveAcceptHandler,
+        handler, typename Protocol::socket) type_check;
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_accept(
+        this->get_implementation(), &io_context, &peer_endpoint,
+        BOOST_ASIO_MOVE_CAST(MoveAcceptHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<MoveAcceptHandler,
+      void (boost::system::error_code,
+        typename Protocol::socket)> init(handler);
+
+    this->get_service().async_accept(this->get_implementation(),
+        &io_context, &peer_endpoint, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 };
 
 } // namespace asio
@@ -1134,4 +1981,8 @@ class basic_socket_acceptor
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# undef BOOST_ASIO_SVC_T
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_BASIC_SOCKET_ACCEPTOR_HPP
diff --git a/include/boost/asio/basic_socket_iostream.hpp b/include/boost/asio/basic_socket_iostream.hpp
index 6ed71f7b68..a5f8e0223a 100644
--- a/include/boost/asio/basic_socket_iostream.hpp
+++ b/include/boost/asio/basic_socket_iostream.hpp
@@ -22,7 +22,10 @@
 #include <istream>
 #include <ostream>
 #include <boost/asio/basic_socket_streambuf.hpp>
-#include <boost/asio/stream_socket_service.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/stream_socket_service.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #if !defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 
@@ -33,8 +36,8 @@
 //   explicit basic_socket_iostream(T1 x1, ..., Tn xn)
 //     : std::basic_iostream<char>(
 //         &this->detail::socket_iostream_base<
-//           Protocol, StreamSocketService, Time,
-//           TimeTraits, TimerService>::streambuf_)
+//           Protocol BOOST_ASIO_SVC_TARG, Clock,
+//           WaitTraits BOOST_ASIO_SVC_TARG1>::streambuf_)
 //   {
 //     if (rdbuf()->connect(x1, ..., xn) == 0)
 //       this->setstate(std::ios_base::failbit);
@@ -43,14 +46,14 @@
 
 # define BOOST_ASIO_PRIVATE_CTR_DEF(n) \
   template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
-  explicit basic_socket_iostream(BOOST_ASIO_VARIADIC_PARAMS(n)) \
+  explicit basic_socket_iostream(BOOST_ASIO_VARIADIC_BYVAL_PARAMS(n)) \
     : std::basic_iostream<char>( \
         &this->detail::socket_iostream_base< \
-          Protocol, StreamSocketService, Time, \
-          TimeTraits, TimerService>::streambuf_) \
+          Protocol BOOST_ASIO_SVC_TARG, Clock, \
+          WaitTraits BOOST_ASIO_SVC_TARG1>::streambuf_) \
   { \
     this->setf(std::ios_base::unitbuf); \
-    if (rdbuf()->connect(BOOST_ASIO_VARIADIC_ARGS(n)) == 0) \
+    if (rdbuf()->connect(BOOST_ASIO_VARIADIC_BYVAL_ARGS(n)) == 0) \
       this->setstate(std::ios_base::failbit); \
   } \
   /**/
@@ -66,9 +69,9 @@
 
 # define BOOST_ASIO_PRIVATE_CONNECT_DEF(n) \
   template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
-  void connect(BOOST_ASIO_VARIADIC_PARAMS(n)) \
+  void connect(BOOST_ASIO_VARIADIC_BYVAL_PARAMS(n)) \
   { \
-    if (rdbuf()->connect(BOOST_ASIO_VARIADIC_ARGS(n)) == 0) \
+    if (rdbuf()->connect(BOOST_ASIO_VARIADIC_BYVAL_ARGS(n)) == 0) \
       this->setstate(std::ios_base::failbit); \
   } \
   /**/
@@ -83,69 +86,163 @@ namespace detail {
 
 // A separate base class is used to ensure that the streambuf is initialised
 // prior to the basic_socket_iostream's basic_iostream base class.
-template <typename Protocol, typename StreamSocketService,
-    typename Time, typename TimeTraits, typename TimerService>
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Clock, typename WaitTraits BOOST_ASIO_SVC_TPARAM1>
 class socket_iostream_base
 {
 protected:
-  basic_socket_streambuf<Protocol, StreamSocketService,
-    Time, TimeTraits, TimerService> streambuf_;
+  socket_iostream_base()
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  socket_iostream_base(socket_iostream_base&& other)
+    : streambuf_(std::move(other.streambuf_))
+  {
+  }
+
+  socket_iostream_base(basic_stream_socket<Protocol> s)
+    : streambuf_(std::move(s))
+  {
+  }
+
+  socket_iostream_base& operator=(socket_iostream_base&& other)
+  {
+    streambuf_ = std::move(other.streambuf_);
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  basic_socket_streambuf<Protocol BOOST_ASIO_SVC_TARG,
+    Clock, WaitTraits BOOST_ASIO_SVC_TARG1> streambuf_;
 };
 
-}
+} // namespace detail
 
-/// Iostream interface for a socket.
-template <typename Protocol,
-    typename StreamSocketService = stream_socket_service<Protocol>,
-#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME) \
-  || defined(GENERATING_DOCUMENTATION)
-    typename Time = boost::posix_time::ptime,
-    typename TimeTraits = boost::asio::time_traits<Time>,
-    typename TimerService = deadline_timer_service<Time, TimeTraits> >
+#if !defined(BOOST_ASIO_BASIC_SOCKET_IOSTREAM_FWD_DECL)
+#define BOOST_ASIO_BASIC_SOCKET_IOSTREAM_FWD_DECL
+
+// Forward declaration with defaulted arguments.
+template <typename Protocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= stream_socket_service<Protocol>),
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+    typename Clock = boost::posix_time::ptime,
+    typename WaitTraits = time_traits<Clock>
+    BOOST_ASIO_SVC_TPARAM1_DEF2(= deadline_timer_service<Clock, WaitTraits>)>
 #else
-    typename Time = steady_timer::clock_type,
-    typename TimeTraits = steady_timer::traits_type,
-    typename TimerService = steady_timer::service_type>
+    typename Clock = chrono::steady_clock,
+    typename WaitTraits = wait_traits<Clock>
+    BOOST_ASIO_SVC_TPARAM1_DEF1(= steady_timer::service_type)>
 #endif
+class basic_socket_iostream;
+
+#endif // !defined(BOOST_ASIO_BASIC_SOCKET_IOSTREAM_FWD_DECL)
+
+/// Iostream interface for a socket.
+#if defined(GENERATING_DOCUMENTATION)
+template <typename Protocol,
+    typename Clock = chrono::steady_clock,
+    typename WaitTraits = wait_traits<Clock> >
+#else // defined(GENERATING_DOCUMENTATION)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Clock, typename WaitTraits BOOST_ASIO_SVC_TPARAM1>
+#endif // defined(GENERATING_DOCUMENTATION)
 class basic_socket_iostream
-  : private detail::socket_iostream_base<Protocol,
-        StreamSocketService, Time, TimeTraits, TimerService>,
+  : private detail::socket_iostream_base<Protocol
+        BOOST_ASIO_SVC_TARG, Clock, WaitTraits BOOST_ASIO_SVC_TARG1>,
     public std::basic_iostream<char>
 {
 private:
   // These typedefs are intended keep this class's implementation independent
-  // of whether it's using Boost.DateTime, Boost.Chrono or std::chrono.
+  // of whether it's using Boost.DateClock, Boost.Chrono or std::chrono.
 #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-  typedef TimeTraits traits_helper;
+  typedef WaitTraits traits_helper;
 #else
-  typedef detail::chrono_time_traits<Time, TimeTraits> traits_helper;
+  typedef detail::chrono_time_traits<Clock, WaitTraits> traits_helper;
 #endif
 
 public:
+  /// The protocol type.
+  typedef Protocol protocol_type;
+
   /// The endpoint type.
   typedef typename Protocol::endpoint endpoint_type;
 
+  /// The clock type.
+  typedef Clock clock_type;
+
 #if defined(GENERATING_DOCUMENTATION)
+  /// (Deprecated: Use time_point.) The time type.
+  typedef typename WaitTraits::time_type time_type;
+
   /// The time type.
-  typedef typename TimeTraits::time_type time_type;
+  typedef typename WaitTraits::time_point time_point;
+
+  /// (Deprecated: Use duration.) The duration type.
+  typedef typename WaitTraits::duration_type duration_type;
 
   /// The duration type.
-  typedef typename TimeTraits::duration_type duration_type;
+  typedef typename WaitTraits::duration duration;
 #else
+# if !defined(BOOST_ASIO_NO_DEPRECATED)
   typedef typename traits_helper::time_type time_type;
   typedef typename traits_helper::duration_type duration_type;
+# endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+  typedef typename traits_helper::time_type time_point;
+  typedef typename traits_helper::duration_type duration;
 #endif
 
   /// Construct a basic_socket_iostream without establishing a connection.
   basic_socket_iostream()
     : std::basic_iostream<char>(
         &this->detail::socket_iostream_base<
-          Protocol, StreamSocketService, Time,
-          TimeTraits, TimerService>::streambuf_)
+          Protocol BOOST_ASIO_SVC_TARG, Clock,
+          WaitTraits BOOST_ASIO_SVC_TARG1>::streambuf_)
+  {
+    this->setf(std::ios_base::unitbuf);
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Construct a basic_socket_iostream from the supplied socket.
+  explicit basic_socket_iostream(basic_stream_socket<protocol_type> s)
+    : detail::socket_iostream_base<
+        Protocol BOOST_ASIO_SVC_TARG, Clock,
+        WaitTraits BOOST_ASIO_SVC_TARG1>(std::move(s)),
+      std::basic_iostream<char>(
+        &this->detail::socket_iostream_base<
+          Protocol BOOST_ASIO_SVC_TARG, Clock,
+          WaitTraits BOOST_ASIO_SVC_TARG1>::streambuf_)
   {
     this->setf(std::ios_base::unitbuf);
   }
 
+#if defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE) \
+  || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a basic_socket_iostream from another.
+  basic_socket_iostream(basic_socket_iostream&& other)
+    : detail::socket_iostream_base<
+        Protocol BOOST_ASIO_SVC_TARG, Clock,
+        WaitTraits BOOST_ASIO_SVC_TARG1>(std::move(other)),
+      std::basic_iostream<char>(std::move(other))
+  {
+    this->set_rdbuf(&this->detail::socket_iostream_base<
+          Protocol BOOST_ASIO_SVC_TARG, Clock,
+          WaitTraits BOOST_ASIO_SVC_TARG1>::streambuf_);
+  }
+
+  /// Move-assign a basic_socket_iostream from another.
+  basic_socket_iostream& operator=(basic_socket_iostream&& other)
+  {
+    std::basic_iostream<char>::operator=(std::move(other));
+    detail::socket_iostream_base<
+        Protocol BOOST_ASIO_SVC_TARG, Clock,
+        WaitTraits BOOST_ASIO_SVC_TARG1>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)
+       //   || defined(GENERATING_DOCUMENTATION)
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
 #if defined(GENERATING_DOCUMENTATION)
   /// Establish a connection to an endpoint corresponding to a resolver query.
   /**
@@ -160,8 +257,8 @@ class basic_socket_iostream
   explicit basic_socket_iostream(T... x)
     : std::basic_iostream<char>(
         &this->detail::socket_iostream_base<
-          Protocol, StreamSocketService, Time,
-          TimeTraits, TimerService>::streambuf_)
+          Protocol BOOST_ASIO_SVC_TARG, Clock,
+          WaitTraits BOOST_ASIO_SVC_TARG1>::streambuf_)
   {
     this->setf(std::ios_base::unitbuf);
     if (rdbuf()->connect(x...) == 0)
@@ -199,14 +296,20 @@ class basic_socket_iostream
   }
 
   /// Return a pointer to the underlying streambuf.
-  basic_socket_streambuf<Protocol, StreamSocketService,
-    Time, TimeTraits, TimerService>* rdbuf() const
+  basic_socket_streambuf<Protocol BOOST_ASIO_SVC_TARG,
+    Clock, WaitTraits BOOST_ASIO_SVC_TARG1>* rdbuf() const
   {
-    return const_cast<basic_socket_streambuf<Protocol, StreamSocketService,
-      Time, TimeTraits, TimerService>*>(
+    return const_cast<basic_socket_streambuf<Protocol BOOST_ASIO_SVC_TARG,
+      Clock, WaitTraits BOOST_ASIO_SVC_TARG1>*>(
         &this->detail::socket_iostream_base<
-          Protocol, StreamSocketService, Time,
-          TimeTraits, TimerService>::streambuf_);
+          Protocol BOOST_ASIO_SVC_TARG, Clock,
+          WaitTraits BOOST_ASIO_SVC_TARG1>::streambuf_);
+  }
+
+  /// Get a reference to the underlying socket.
+  basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket()
+  {
+    return rdbuf()->socket();
   }
 
   /// Get the last error associated with the stream.
@@ -223,17 +326,29 @@ class basic_socket_iostream
    */
   const boost::system::error_code& error() const
   {
-    return rdbuf()->puberror();
+    return rdbuf()->error();
   }
 
-  /// Get the stream's expiry time as an absolute time.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use expiry().) Get the stream's expiry time as an absolute
+  /// time.
   /**
    * @return An absolute time value representing the stream's expiry time.
    */
-  time_type expires_at() const
+  time_point expires_at() const
   {
     return rdbuf()->expires_at();
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the stream's expiry time as an absolute time.
+  /**
+   * @return An absolute time value representing the stream's expiry time.
+   */
+  time_point expiry() const
+  {
+    return rdbuf()->expiry();
+  }
 
   /// Set the stream's expiry time as an absolute time.
   /**
@@ -244,21 +359,37 @@ class basic_socket_iostream
    *
    * @param expiry_time The expiry time to be used for the stream.
    */
-  void expires_at(const time_type& expiry_time)
+  void expires_at(const time_point& expiry_time)
   {
     rdbuf()->expires_at(expiry_time);
   }
 
-  /// Get the timer's expiry time relative to now.
+  /// Set the stream's expiry time relative to now.
+  /**
+   * This function sets the expiry time associated with the stream. Stream
+   * operations performed after this time (where the operations cannot be
+   * completed using the internal buffers) will fail with the error
+   * boost::asio::error::operation_aborted.
+   *
+   * @param expiry_time The expiry time to be used for the timer.
+   */
+  void expires_after(const duration& expiry_time)
+  {
+    rdbuf()->expires_after(expiry_time);
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use expiry().) Get the stream's expiry time relative to now.
   /**
    * @return A relative time value representing the stream's expiry time.
    */
-  duration_type expires_from_now() const
+  duration expires_from_now() const
   {
     return rdbuf()->expires_from_now();
   }
 
-  /// Set the stream's expiry time relative to now.
+  /// (Deprecated: Use expires_after().) Set the stream's expiry time relative
+  /// to now.
   /**
    * This function sets the expiry time associated with the stream. Stream
    * operations performed after this time (where the operations cannot be
@@ -267,10 +398,17 @@ class basic_socket_iostream
    *
    * @param expiry_time The expiry time to be used for the timer.
    */
-  void expires_from_now(const duration_type& expiry_time)
+  void expires_from_now(const duration& expiry_time)
   {
     rdbuf()->expires_from_now(expiry_time);
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+private:
+  // Disallow copying and assignment.
+  basic_socket_iostream(const basic_socket_iostream&) BOOST_ASIO_DELETED;
+  basic_socket_iostream& operator=(
+      const basic_socket_iostream&) BOOST_ASIO_DELETED;
 };
 
 } // namespace asio
diff --git a/include/boost/asio/basic_socket_streambuf.hpp b/include/boost/asio/basic_socket_streambuf.hpp
index 922b005d88..352225b876 100644
--- a/include/boost/asio/basic_socket_streambuf.hpp
+++ b/include/boost/asio/basic_socket_streambuf.hpp
@@ -20,15 +20,24 @@
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 #include <streambuf>
+#include <vector>
 #include <boost/asio/basic_socket.hpp>
-#include <boost/asio/deadline_timer_service.hpp>
-#include <boost/asio/detail/array.hpp>
+#include <boost/asio/basic_stream_socket.hpp>
+#include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/throw_error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/stream_socket_service.hpp>
+#include <boost/asio/io_context.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/stream_socket_service.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-# include <boost/asio/deadline_timer.hpp>
+# if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+#  include <boost/asio/deadline_timer_service.hpp>
+# else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+#  include <boost/asio/detail/deadline_timer_service.hpp>
+# endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 #else
 # include <boost/asio/steady_timer.hpp>
 #endif
@@ -39,113 +48,214 @@
 
 // A macro that should expand to:
 //   template <typename T1, ..., typename Tn>
-//   basic_socket_streambuf<Protocol, StreamSocketService,
-//     Time, TimeTraits, TimerService>* connect(
-//       T1 x1, ..., Tn xn)
+//   basic_socket_streambuf* connect(T1 x1, ..., Tn xn)
 //   {
 //     init_buffers();
-//     this->basic_socket<Protocol, StreamSocketService>::close(ec_);
 //     typedef typename Protocol::resolver resolver_type;
-//     typedef typename resolver_type::query resolver_query;
-//     resolver_query query(x1, ..., xn);
-//     resolve_and_connect(query);
+//     resolver_type resolver(socket().get_executor().context());
+//     connect_to_endpoints(
+//         resolver.resolve(x1, ..., xn, ec_));
 //     return !ec_ ? this : 0;
 //   }
 // This macro should only persist within this file.
 
 # define BOOST_ASIO_PRIVATE_CONNECT_DEF(n) \
   template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
-  basic_socket_streambuf<Protocol, StreamSocketService, \
-    Time, TimeTraits, TimerService>* connect(BOOST_ASIO_VARIADIC_PARAMS(n)) \
+  basic_socket_streambuf* connect(BOOST_ASIO_VARIADIC_BYVAL_PARAMS(n)) \
   { \
     init_buffers(); \
-    this->basic_socket<Protocol, StreamSocketService>::close(ec_); \
     typedef typename Protocol::resolver resolver_type; \
-    typedef typename resolver_type::query resolver_query; \
-    resolver_query query(BOOST_ASIO_VARIADIC_ARGS(n)); \
-    resolve_and_connect(query); \
+    resolver_type resolver(socket().get_executor().context()); \
+    connect_to_endpoints( \
+        resolver.resolve(BOOST_ASIO_VARIADIC_BYVAL_ARGS(n), ec_)); \
     return !ec_ ? this : 0; \
   } \
   /**/
 
 #endif // !defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# define BOOST_ASIO_SVC_T1 detail::deadline_timer_service<traits_helper>
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 namespace detail {
 
-// A separate base class is used to ensure that the io_service is initialised
-// prior to the basic_socket_streambuf's basic_socket base class.
-class socket_streambuf_base
+// A separate base class is used to ensure that the io_context member is
+// initialised prior to the basic_socket_streambuf's basic_socket base class.
+class socket_streambuf_io_context
+{
+protected:
+  socket_streambuf_io_context(io_context* ctx)
+    : default_io_context_(ctx)
+  {
+  }
+
+  shared_ptr<io_context> default_io_context_;
+};
+
+// A separate base class is used to ensure that the dynamically allocated
+// buffers are constructed prior to the basic_socket_streambuf's basic_socket
+// base class. This makes moving the socket is the last potentially throwing
+// step in the streambuf's move constructor, giving the constructor a strong
+// exception safety guarantee.
+class socket_streambuf_buffers
 {
 protected:
-  io_service io_service_;
+  socket_streambuf_buffers()
+    : get_buffer_(buffer_size),
+      put_buffer_(buffer_size)
+  {
+  }
+
+  enum { buffer_size = 512 };
+  std::vector<char> get_buffer_;
+  std::vector<char> put_buffer_;
 };
 
 } // namespace detail
 
-/// Iostream streambuf for a socket.
-template <typename Protocol,
-    typename StreamSocketService = stream_socket_service<Protocol>,
-#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME) \
-  || defined(GENERATING_DOCUMENTATION)
-    typename Time = boost::posix_time::ptime,
-    typename TimeTraits = boost::asio::time_traits<Time>,
-    typename TimerService = deadline_timer_service<Time, TimeTraits> >
+#if !defined(BOOST_ASIO_BASIC_SOCKET_STREAMBUF_FWD_DECL)
+#define BOOST_ASIO_BASIC_SOCKET_STREAMBUF_FWD_DECL
+
+// Forward declaration with defaulted arguments.
+template <typename Protocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= stream_socket_service<Protocol>),
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+    typename Clock = boost::posix_time::ptime,
+    typename WaitTraits = time_traits<Clock>
+    BOOST_ASIO_SVC_TPARAM1_DEF2(= deadline_timer_service<Clock, WaitTraits>)>
 #else
-    typename Time = steady_timer::clock_type,
-    typename TimeTraits = steady_timer::traits_type,
-    typename TimerService = steady_timer::service_type>
+    typename Clock = chrono::steady_clock,
+    typename WaitTraits = wait_traits<Clock>
+    BOOST_ASIO_SVC_TPARAM1_DEF1(= steady_timer::service_type)>
 #endif
+class basic_socket_streambuf;
+
+#endif // !defined(BOOST_ASIO_BASIC_SOCKET_STREAMBUF_FWD_DECL)
+
+/// Iostream streambuf for a socket.
+#if defined(GENERATING_DOCUMENTATION)
+template <typename Protocol,
+    typename Clock = chrono::steady_clock,
+    typename WaitTraits = wait_traits<Clock> >
+#else // defined(GENERATING_DOCUMENTATION)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Clock, typename WaitTraits BOOST_ASIO_SVC_TPARAM1>
+#endif // defined(GENERATING_DOCUMENTATION)
 class basic_socket_streambuf
   : public std::streambuf,
-    private detail::socket_streambuf_base,
-    public basic_socket<Protocol, StreamSocketService>
+    private detail::socket_streambuf_io_context,
+    private detail::socket_streambuf_buffers,
+#if defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+    private basic_socket<Protocol BOOST_ASIO_SVC_TARG>
+#else // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+    public basic_socket<Protocol BOOST_ASIO_SVC_TARG>
+#endif // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
 {
 private:
   // These typedefs are intended keep this class's implementation independent
-  // of whether it's using Boost.DateTime, Boost.Chrono or std::chrono.
+  // of whether it's using Boost.DateClock, Boost.Chrono or std::chrono.
 #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-  typedef TimeTraits traits_helper;
+  typedef WaitTraits traits_helper;
 #else
-  typedef detail::chrono_time_traits<Time, TimeTraits> traits_helper;
+  typedef detail::chrono_time_traits<Clock, WaitTraits> traits_helper;
 #endif
 
 public:
+  /// The protocol type.
+  typedef Protocol protocol_type;
+
   /// The endpoint type.
   typedef typename Protocol::endpoint endpoint_type;
 
+  /// The clock type.
+  typedef Clock clock_type;
+
 #if defined(GENERATING_DOCUMENTATION)
+  /// (Deprecated: Use time_point.) The time type.
+  typedef typename WaitTraits::time_type time_type;
+
   /// The time type.
-  typedef typename TimeTraits::time_type time_type;
+  typedef typename WaitTraits::time_point time_point;
+
+  /// (Deprecated: Use duration.) The duration type.
+  typedef typename WaitTraits::duration_type duration_type;
 
   /// The duration type.
-  typedef typename TimeTraits::duration_type duration_type;
+  typedef typename WaitTraits::duration duration;
 #else
+# if !defined(BOOST_ASIO_NO_DEPRECATED)
   typedef typename traits_helper::time_type time_type;
   typedef typename traits_helper::duration_type duration_type;
+# endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+  typedef typename traits_helper::time_type time_point;
+  typedef typename traits_helper::duration_type duration;
 #endif
 
   /// Construct a basic_socket_streambuf without establishing a connection.
   basic_socket_streambuf()
-    : basic_socket<Protocol, StreamSocketService>(
-        this->detail::socket_streambuf_base::io_service_),
-      unbuffered_(false),
-      timer_service_(0),
-      timer_state_(no_timer)
+    : detail::socket_streambuf_io_context(new io_context),
+      basic_socket<Protocol BOOST_ASIO_SVC_TARG>(*default_io_context_),
+      expiry_time_(max_expiry_time())
+  {
+    init_buffers();
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Construct a basic_socket_streambuf from the supplied socket.
+  explicit basic_socket_streambuf(basic_stream_socket<protocol_type> s)
+    : detail::socket_streambuf_io_context(0),
+      basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(s)),
+      expiry_time_(max_expiry_time())
   {
     init_buffers();
   }
 
+  /// Move-construct a basic_socket_streambuf from another.
+  basic_socket_streambuf(basic_socket_streambuf&& other)
+    : detail::socket_streambuf_io_context(other),
+      basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other.socket())),
+      ec_(other.ec_),
+      expiry_time_(other.expiry_time_)
+  {
+    get_buffer_.swap(other.get_buffer_);
+    put_buffer_.swap(other.put_buffer_);
+    setg(other.eback(), other.gptr(), other.egptr());
+    setp(other.pptr(), other.epptr());
+    other.ec_ = boost::system::error_code();
+    other.expiry_time_ = max_expiry_time();
+    other.init_buffers();
+  }
+
+  /// Move-assign a basic_socket_streambuf from another.
+  basic_socket_streambuf& operator=(basic_socket_streambuf&& other)
+  {
+    this->close();
+    socket() = std::move(other.socket());
+    detail::socket_streambuf_io_context::operator=(other);
+    ec_ = other.ec_;
+    expiry_time_ = other.expiry_time_;
+    get_buffer_.swap(other.get_buffer_);
+    put_buffer_.swap(other.put_buffer_);
+    setg(other.eback(), other.gptr(), other.egptr());
+    setp(other.pptr(), other.epptr());
+    other.ec_ = boost::system::error_code();
+    other.expiry_time_ = max_expiry_time();
+    other.put_buffer_.resize(buffer_size);
+    other.init_buffers();
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
   /// Destructor flushes buffered data.
   virtual ~basic_socket_streambuf()
   {
     if (pptr() != pbase())
       overflow(traits_type::eof());
-
-    destroy_timer();
   }
 
   /// Establish a connection.
@@ -155,29 +265,11 @@ class basic_socket_streambuf
    * @return \c this if a connection was successfully established, a null
    * pointer otherwise.
    */
-  basic_socket_streambuf<Protocol, StreamSocketService,
-    Time, TimeTraits, TimerService>* connect(
-      const endpoint_type& endpoint)
+  basic_socket_streambuf* connect(const endpoint_type& endpoint)
   {
     init_buffers();
-
-    this->basic_socket<Protocol, StreamSocketService>::close(ec_);
-
-    if (timer_state_ == timer_has_expired)
-    {
-      ec_ = boost::asio::error::operation_aborted;
-      return 0;
-    }
-
-    io_handler handler = { this };
-    this->basic_socket<Protocol, StreamSocketService>::async_connect(
-        endpoint, handler);
-
-    ec_ = boost::asio::error::would_block;
-    this->get_service().get_io_service().reset();
-    do this->get_service().get_io_service().run_one();
-    while (ec_ == boost::asio::error::would_block);
-
+    ec_ = boost::system::error_code();
+    this->connect_to_endpoints(&endpoint, &endpoint + 1);
     return !ec_ ? this : 0;
   }
 
@@ -192,19 +284,15 @@ class basic_socket_streambuf
    * pointer otherwise.
    */
   template <typename T1, ..., typename TN>
-  basic_socket_streambuf<Protocol, StreamSocketService>* connect(
-      T1 t1, ..., TN tn);
+  basic_socket_streambuf* connect(T1 t1, ..., TN tn);
 #elif defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
   template <typename... T>
-  basic_socket_streambuf<Protocol, StreamSocketService,
-    Time, TimeTraits, TimerService>* connect(T... x)
+  basic_socket_streambuf* connect(T... x)
   {
     init_buffers();
-    this->basic_socket<Protocol, StreamSocketService>::close(ec_);
     typedef typename Protocol::resolver resolver_type;
-    typedef typename resolver_type::query resolver_query;
-    resolver_query query(x...);
-    resolve_and_connect(query);
+    resolver_type resolver(socket().get_executor().context());
+    connect_to_endpoints(resolver.resolve(x..., ec_));
     return !ec_ ? this : 0;
   }
 #else
@@ -216,17 +304,34 @@ class basic_socket_streambuf
    * @return \c this if a connection was successfully established, a null
    * pointer otherwise.
    */
-  basic_socket_streambuf<Protocol, StreamSocketService,
-    Time, TimeTraits, TimerService>* close()
+  basic_socket_streambuf* close()
   {
     sync();
-    this->basic_socket<Protocol, StreamSocketService>::close(ec_);
+    socket().close(ec_);
     if (!ec_)
       init_buffers();
     return !ec_ ? this : 0;
   }
 
+  /// Get a reference to the underlying socket.
+  basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket()
+  {
+    return *this;
+  }
+
   /// Get the last error associated with the stream buffer.
+  /**
+   * @return An \c error_code corresponding to the last error from the stream
+   * buffer.
+   */
+  const boost::system::error_code& error() const
+  {
+    return ec_;
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use error().) Get the last error associated with the stream
+  /// buffer.
   /**
    * @return An \c error_code corresponding to the last error from the stream
    * buffer.
@@ -236,16 +341,26 @@ class basic_socket_streambuf
     return error();
   }
 
+  /// (Deprecated: Use expiry().) Get the stream buffer's expiry time as an
+  /// absolute time.
+  /**
+   * @return An absolute time value representing the stream buffer's expiry
+   * time.
+   */
+  time_point expires_at() const
+  {
+    return expiry_time_;
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
   /// Get the stream buffer's expiry time as an absolute time.
   /**
    * @return An absolute time value representing the stream buffer's expiry
    * time.
    */
-  time_type expires_at() const
+  time_point expiry() const
   {
-    return timer_service_
-      ? timer_service_->expires_at(timer_implementation_)
-      : time_type();
+    return expiry_time_;
   }
 
   /// Set the stream buffer's expiry time as an absolute time.
@@ -257,27 +372,38 @@ class basic_socket_streambuf
    *
    * @param expiry_time The expiry time to be used for the stream.
    */
-  void expires_at(const time_type& expiry_time)
+  void expires_at(const time_point& expiry_time)
   {
-    construct_timer();
-
-    boost::system::error_code ec;
-    timer_service_->expires_at(timer_implementation_, expiry_time, ec);
-    boost::asio::detail::throw_error(ec, "expires_at");
+    expiry_time_ = expiry_time;
+  }
 
-    start_timer();
+  /// Set the stream buffer's expiry time relative to now.
+  /**
+   * This function sets the expiry time associated with the stream. Stream
+   * operations performed after this time (where the operations cannot be
+   * completed using the internal buffers) will fail with the error
+   * boost::asio::error::operation_aborted.
+   *
+   * @param expiry_time The expiry time to be used for the timer.
+   */
+  void expires_after(const duration& expiry_time)
+  {
+    expiry_time_ = traits_helper::add(traits_helper::now(), expiry_time);
   }
 
-  /// Get the stream buffer's expiry time relative to now.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use expiry().) Get the stream buffer's expiry time relative
+  /// to now.
   /**
    * @return A relative time value representing the stream buffer's expiry time.
    */
-  duration_type expires_from_now() const
+  duration expires_from_now() const
   {
     return traits_helper::subtract(expires_at(), traits_helper::now());
   }
 
-  /// Set the stream buffer's expiry time relative to now.
+  /// (Deprecated: Use expires_after().) Set the stream buffer's expiry time
+  /// relative to now.
   /**
    * This function sets the expiry time associated with the stream. Stream
    * operations performed after this time (where the operations cannot be
@@ -286,109 +412,126 @@ class basic_socket_streambuf
    *
    * @param expiry_time The expiry time to be used for the timer.
    */
-  void expires_from_now(const duration_type& expiry_time)
+  void expires_from_now(const duration& expiry_time)
   {
-    construct_timer();
-
-    boost::system::error_code ec;
-    timer_service_->expires_from_now(timer_implementation_, expiry_time, ec);
-    boost::asio::detail::throw_error(ec, "expires_from_now");
-
-    start_timer();
+    expiry_time_ = traits_helper::add(traits_helper::now(), expiry_time);
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 protected:
   int_type underflow()
   {
-    if (gptr() == egptr())
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+    ec_ = boost::asio::error::operation_not_supported;
+    return traits_type::eof();
+#else // defined(BOOST_ASIO_WINDOWS_RUNTIME)
+    if (gptr() != egptr())
+      return traits_type::eof();
+
+    for (;;)
     {
-      if (timer_state_ == timer_has_expired)
+      // Check if we are past the expiry time.
+      if (traits_helper::less_than(expiry_time_, traits_helper::now()))
       {
-        ec_ = boost::asio::error::operation_aborted;
+        ec_ = boost::asio::error::timed_out;
         return traits_type::eof();
       }
 
-      io_handler handler = { this };
-      this->get_service().async_receive(this->get_implementation(),
-          boost::asio::buffer(boost::asio::buffer(get_buffer_) + putback_max),
-          0, handler);
+      // Try to complete the operation without blocking.
+      if (!socket().native_non_blocking())
+        socket().native_non_blocking(true, ec_);
+      detail::buffer_sequence_adapter<mutable_buffer, mutable_buffer>
+        bufs(boost::asio::buffer(get_buffer_) + putback_max);
+      detail::signed_size_type bytes = detail::socket_ops::recv(
+          socket().native_handle(), bufs.buffers(), bufs.count(), 0, ec_);
 
-      ec_ = boost::asio::error::would_block;
-      this->get_service().get_io_service().reset();
-      do this->get_service().get_io_service().run_one();
-      while (ec_ == boost::asio::error::would_block);
-      if (ec_)
+      // Check if operation succeeded.
+      if (bytes > 0)
+      {
+        setg(&get_buffer_[0], &get_buffer_[0] + putback_max,
+            &get_buffer_[0] + putback_max + bytes);
+        return traits_type::to_int_type(*gptr());
+      }
+
+      // Check for EOF.
+      if (bytes == 0)
+      {
+        ec_ = boost::asio::error::eof;
         return traits_type::eof();
+      }
 
-      setg(&get_buffer_[0], &get_buffer_[0] + putback_max,
-          &get_buffer_[0] + putback_max + bytes_transferred_);
-      return traits_type::to_int_type(*gptr());
-    }
-    else
-    {
-      return traits_type::eof();
+      // Operation failed.
+      if (ec_ != boost::asio::error::would_block
+          && ec_ != boost::asio::error::try_again)
+        return traits_type::eof();
+
+      // Wait for socket to become ready.
+      if (detail::socket_ops::poll_read(
+            socket().native_handle(), 0, timeout(), ec_) < 0)
+        return traits_type::eof();
     }
+#endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
   }
 
   int_type overflow(int_type c)
   {
-    if (unbuffered_)
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+    ec_ = boost::asio::error::operation_not_supported;
+    return traits_type::eof();
+#else // defined(BOOST_ASIO_WINDOWS_RUNTIME)
+    char_type ch = traits_type::to_char_type(c);
+
+    // Determine what needs to be sent.
+    const_buffer output_buffer;
+    if (put_buffer_.empty())
     {
       if (traits_type::eq_int_type(c, traits_type::eof()))
+        return traits_type::not_eof(c); // Nothing to do.
+      output_buffer = boost::asio::buffer(&ch, sizeof(char_type));
+    }
+    else
+    {
+      output_buffer = boost::asio::buffer(pbase(),
+          (pptr() - pbase()) * sizeof(char_type));
+    }
+
+    while (output_buffer.size() > 0)
+    {
+      // Check if we are past the expiry time.
+      if (traits_helper::less_than(expiry_time_, traits_helper::now()))
       {
-        // Nothing to do.
-        return traits_type::not_eof(c);
+        ec_ = boost::asio::error::timed_out;
+        return traits_type::eof();
       }
-      else
+
+      // Try to complete the operation without blocking.
+      if (!socket().native_non_blocking())
+        socket().native_non_blocking(true, ec_);
+      detail::buffer_sequence_adapter<
+        const_buffer, const_buffer> bufs(output_buffer);
+      detail::signed_size_type bytes = detail::socket_ops::send(
+          socket().native_handle(), bufs.buffers(), bufs.count(), 0, ec_);
+
+      // Check if operation succeeded.
+      if (bytes > 0)
       {
-        if (timer_state_ == timer_has_expired)
-        {
-          ec_ = boost::asio::error::operation_aborted;
-          return traits_type::eof();
-        }
-
-        // Send the single character immediately.
-        char_type ch = traits_type::to_char_type(c);
-        io_handler handler = { this };
-        this->get_service().async_send(this->get_implementation(),
-            boost::asio::buffer(&ch, sizeof(char_type)), 0, handler);
-
-        ec_ = boost::asio::error::would_block;
-        this->get_service().get_io_service().reset();
-        do this->get_service().get_io_service().run_one();
-        while (ec_ == boost::asio::error::would_block);
-        if (ec_)
-          return traits_type::eof();
-
-        return c;
+        output_buffer += static_cast<std::size_t>(bytes);
+        continue;
       }
+
+      // Operation failed.
+      if (ec_ != boost::asio::error::would_block
+          && ec_ != boost::asio::error::try_again)
+        return traits_type::eof();
+
+      // Wait for socket to become ready.
+      if (detail::socket_ops::poll_write(
+            socket().native_handle(), 0, timeout(), ec_) < 0)
+        return traits_type::eof();
     }
-    else
+
+    if (!put_buffer_.empty())
     {
-      // Send all data in the output buffer.
-      boost::asio::const_buffer buffer =
-        boost::asio::buffer(pbase(), pptr() - pbase());
-      while (boost::asio::buffer_size(buffer) > 0)
-      {
-        if (timer_state_ == timer_has_expired)
-        {
-          ec_ = boost::asio::error::operation_aborted;
-          return traits_type::eof();
-        }
-
-        io_handler handler = { this };
-        this->get_service().async_send(this->get_implementation(),
-            boost::asio::buffer(buffer), 0, handler);
-
-        ec_ = boost::asio::error::would_block;
-        this->get_service().get_io_service().reset();
-        do this->get_service().get_io_service().run_one();
-        while (ec_ == boost::asio::error::would_block);
-        if (ec_)
-          return traits_type::eof();
-
-        buffer = buffer + bytes_transferred_;
-      }
       setp(&put_buffer_[0], &put_buffer_[0] + put_buffer_.size());
 
       // If the new character is eof then our work here is done.
@@ -396,10 +539,12 @@ class basic_socket_streambuf
         return traits_type::not_eof(c);
 
       // Add the new character to the output buffer.
-      *pptr() = traits_type::to_char_type(c);
+      *pptr() = ch;
       pbump(1);
-      return c;
     }
+
+    return c;
+#endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
   }
 
   int sync()
@@ -411,148 +556,127 @@ class basic_socket_streambuf
   {
     if (pptr() == pbase() && s == 0 && n == 0)
     {
-      unbuffered_ = true;
+      put_buffer_.clear();
       setp(0, 0);
+      sync();
       return this;
     }
 
     return 0;
   }
 
-  /// Get the last error associated with the stream buffer.
-  /**
-   * @return An \c error_code corresponding to the last error from the stream
-   * buffer.
-   */
-  virtual const boost::system::error_code& error() const
-  {
-    return ec_;
-  }
-
 private:
+  // Disallow copying and assignment.
+  basic_socket_streambuf(const basic_socket_streambuf&) BOOST_ASIO_DELETED;
+  basic_socket_streambuf& operator=(
+      const basic_socket_streambuf&) BOOST_ASIO_DELETED;
+
   void init_buffers()
   {
     setg(&get_buffer_[0],
         &get_buffer_[0] + putback_max,
         &get_buffer_[0] + putback_max);
-    if (unbuffered_)
+
+    if (put_buffer_.empty())
       setp(0, 0);
     else
       setp(&put_buffer_[0], &put_buffer_[0] + put_buffer_.size());
   }
 
-  template <typename ResolverQuery>
-  void resolve_and_connect(const ResolverQuery& query)
+  int timeout() const
   {
-    typedef typename Protocol::resolver resolver_type;
-    typedef typename resolver_type::iterator iterator_type;
-    resolver_type resolver(detail::socket_streambuf_base::io_service_);
-    iterator_type i = resolver.resolve(query, ec_);
-    if (!ec_)
-    {
-      iterator_type end;
-      ec_ = boost::asio::error::host_not_found;
-      while (ec_ && i != end)
-      {
-        this->basic_socket<Protocol, StreamSocketService>::close(ec_);
-
-        if (timer_state_ == timer_has_expired)
-        {
-          ec_ = boost::asio::error::operation_aborted;
-          return;
-        }
-
-        io_handler handler = { this };
-        this->basic_socket<Protocol, StreamSocketService>::async_connect(
-            *i, handler);
-
-        ec_ = boost::asio::error::would_block;
-        this->get_service().get_io_service().reset();
-        do this->get_service().get_io_service().run_one();
-        while (ec_ == boost::asio::error::would_block);
-
-        ++i;
-      }
-    }
+    int64_t msec = traits_helper::to_posix_duration(
+        traits_helper::subtract(expiry_time_,
+          traits_helper::now())).total_milliseconds();
+    if (msec > (std::numeric_limits<int>::max)())
+      msec = (std::numeric_limits<int>::max)();
+    else if (msec < 0)
+      msec = 0;
+    return static_cast<int>(msec);
   }
 
-  struct io_handler;
-  friend struct io_handler;
-  struct io_handler
+  template <typename EndpointSequence>
+  void connect_to_endpoints(const EndpointSequence& endpoints)
   {
-    basic_socket_streambuf* this_;
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred = 0)
-    {
-      this_->ec_ = ec;
-      this_->bytes_transferred_ = bytes_transferred;
-    }
-  };
+    this->connect_to_endpoints(endpoints.begin(), endpoints.end());
+  }
 
-  struct timer_handler;
-  friend struct timer_handler;
-  struct timer_handler
+  template <typename EndpointIterator>
+  void connect_to_endpoints(EndpointIterator begin, EndpointIterator end)
   {
-    basic_socket_streambuf* this_;
-
-    void operator()(const boost::system::error_code&)
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+    ec_ = boost::asio::error::operation_not_supported;
+#else // defined(BOOST_ASIO_WINDOWS_RUNTIME)
+    if (ec_)
+      return;
+
+    ec_ = boost::asio::error::not_found;
+    for (EndpointIterator i = begin; i != end; ++i)
     {
-      time_type now = traits_helper::now();
-
-      time_type expiry_time = this_->timer_service_->expires_at(
-            this_->timer_implementation_);
-
-      if (traits_helper::less_than(now, expiry_time))
+      // Check if we are past the expiry time.
+      if (traits_helper::less_than(expiry_time_, traits_helper::now()))
       {
-        this_->timer_state_ = timer_is_pending;
-        this_->timer_service_->async_wait(this_->timer_implementation_, *this);
+        ec_ = boost::asio::error::timed_out;
+        return;
       }
-      else
-      {
-        this_->timer_state_ = timer_has_expired;
-        boost::system::error_code ec;
-        this_->basic_socket<Protocol, StreamSocketService>::close(ec);
-      }
-    }
-  };
 
-  void construct_timer()
-  {
-    if (timer_service_ == 0)
-    {
-      TimerService& timer_service = use_service<TimerService>(
-          detail::socket_streambuf_base::io_service_);
-      timer_service.construct(timer_implementation_);
-      timer_service_ = &timer_service;
+      // Close and reopen the socket.
+      typename Protocol::endpoint ep(*i);
+      socket().close(ec_);
+      socket().open(ep.protocol(), ec_);
+      if (ec_)
+        continue;
+
+      // Try to complete the operation without blocking.
+      if (!socket().native_non_blocking())
+        socket().native_non_blocking(true, ec_);
+      detail::socket_ops::connect(socket().native_handle(),
+          ep.data(), ep.size(), ec_);
+
+      // Check if operation succeeded.
+      if (!ec_)
+        return;
+
+      // Operation failed.
+      if (ec_ != boost::asio::error::in_progress
+          && ec_ != boost::asio::error::would_block)
+        continue;
+
+      // Wait for socket to become ready.
+      if (detail::socket_ops::poll_connect(
+            socket().native_handle(), timeout(), ec_) < 0)
+        continue;
+
+      // Get the error code from the connect operation.
+      int connect_error = 0;
+      size_t connect_error_len = sizeof(connect_error);
+      if (detail::socket_ops::getsockopt(socket().native_handle(), 0,
+            SOL_SOCKET, SO_ERROR, &connect_error, &connect_error_len, ec_)
+          == detail::socket_error_retval)
+        return;
+
+      // Check the result of the connect operation.
+      ec_ = boost::system::error_code(connect_error,
+          boost::asio::error::get_system_category());
+      if (!ec_)
+        return;
     }
+#endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
   }
 
-  void destroy_timer()
+  // Helper function to get the maximum expiry time.
+  static time_point max_expiry_time()
   {
-    if (timer_service_)
-      timer_service_->destroy(timer_implementation_);
-  }
-
-  void start_timer()
-  {
-    if (timer_state_ != timer_is_pending)
-    {
-      timer_handler handler = { this };
-      handler(boost::system::error_code());
-    }
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+    return boost::posix_time::pos_infin;
+#else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+    return (time_point::max)();
+#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
   }
 
   enum { putback_max = 8 };
-  enum { buffer_size = 512 };
-  boost::asio::detail::array<char, buffer_size> get_buffer_;
-  boost::asio::detail::array<char, buffer_size> put_buffer_;
-  bool unbuffered_;
   boost::system::error_code ec_;
-  std::size_t bytes_transferred_;
-  TimerService* timer_service_;
-  typename TimerService::implementation_type timer_implementation_;
-  enum state { no_timer, timer_is_pending, timer_has_expired } timer_state_;
+  time_point expiry_time_;
 };
 
 } // namespace asio
@@ -560,6 +684,10 @@ class basic_socket_streambuf
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# undef BOOST_ASIO_SVC_T1
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if !defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 # undef BOOST_ASIO_PRIVATE_CONNECT_DEF
 #endif // !defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
diff --git a/include/boost/asio/basic_stream_socket.hpp b/include/boost/asio/basic_stream_socket.hpp
index 5b959d7db8..709e214a37 100644
--- a/include/boost/asio/basic_stream_socket.hpp
+++ b/include/boost/asio/basic_stream_socket.hpp
@@ -22,7 +22,10 @@
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/stream_socket_service.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/stream_socket_service.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -41,18 +44,19 @@ namespace asio {
  * @par Concepts:
  * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream.
  */
-template <typename Protocol,
-    typename StreamSocketService = stream_socket_service<Protocol> >
+template <typename Protocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= stream_socket_service<Protocol>)>
 class basic_stream_socket
-  : public basic_socket<Protocol, StreamSocketService>
+  : public basic_socket<Protocol BOOST_ASIO_SVC_TARG>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// socket.
-  typedef typename StreamSocketService::native_handle_type native_type;
-
   /// The native representation of a socket.
-  typedef typename StreamSocketService::native_handle_type native_handle_type;
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef typename basic_socket<
+    Protocol BOOST_ASIO_SVC_TARG>::native_handle_type native_handle_type;
+#endif
 
   /// The protocol type.
   typedef Protocol protocol_type;
@@ -66,11 +70,11 @@ class basic_stream_socket
    * needs to be opened and then connected or accepted before data can be sent
    * or received on it.
    *
-   * @param io_service The io_service object that the stream socket will use to
+   * @param io_context The io_context object that the stream socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    */
-  explicit basic_stream_socket(boost::asio::io_service& io_service)
-    : basic_socket<Protocol, StreamSocketService>(io_service)
+  explicit basic_stream_socket(boost::asio::io_context& io_context)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context)
   {
   }
 
@@ -79,16 +83,16 @@ class basic_stream_socket
    * This constructor creates and opens a stream socket. The socket needs to be
    * connected or accepted before data can be sent or received on it.
    *
-   * @param io_service The io_service object that the stream socket will use to
+   * @param io_context The io_context object that the stream socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    *
    * @param protocol An object specifying protocol parameters to be used.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_stream_socket(boost::asio::io_service& io_service,
+  basic_stream_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol)
-    : basic_socket<Protocol, StreamSocketService>(io_service, protocol)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, protocol)
   {
   }
 
@@ -99,7 +103,7 @@ class basic_stream_socket
    * to the specified endpoint on the local machine. The protocol used is the
    * protocol associated with the given endpoint.
    *
-   * @param io_service The io_service object that the stream socket will use to
+   * @param io_context The io_context object that the stream socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    *
    * @param endpoint An endpoint on the local machine to which the stream
@@ -107,9 +111,9 @@ class basic_stream_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_stream_socket(boost::asio::io_service& io_service,
+  basic_stream_socket(boost::asio::io_context& io_context,
       const endpoint_type& endpoint)
-    : basic_socket<Protocol, StreamSocketService>(io_service, endpoint)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(io_context, endpoint)
   {
   }
 
@@ -118,7 +122,7 @@ class basic_stream_socket
    * This constructor creates a stream socket object to hold an existing native
    * socket.
    *
-   * @param io_service The io_service object that the stream socket will use to
+   * @param io_context The io_context object that the stream socket will use to
    * dispatch handlers for any asynchronous operations performed on the socket.
    *
    * @param protocol An object specifying protocol parameters to be used.
@@ -127,10 +131,10 @@ class basic_stream_socket
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_stream_socket(boost::asio::io_service& io_service,
+  basic_stream_socket(boost::asio::io_context& io_context,
       const protocol_type& protocol, const native_handle_type& native_socket)
-    : basic_socket<Protocol, StreamSocketService>(
-        io_service, protocol, native_socket)
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(
+        io_context, protocol, native_socket)
   {
   }
 
@@ -143,11 +147,10 @@ class basic_stream_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_socket(io_service&) constructor.
+   * constructed using the @c basic_stream_socket(io_context&) constructor.
    */
   basic_stream_socket(basic_stream_socket&& other)
-    : basic_socket<Protocol, StreamSocketService>(
-        BOOST_ASIO_MOVE_CAST(basic_stream_socket)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -159,12 +162,11 @@ class basic_stream_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_socket(io_service&) constructor.
+   * constructed using the @c basic_stream_socket(io_context&) constructor.
    */
   basic_stream_socket& operator=(basic_stream_socket&& other)
   {
-    basic_socket<Protocol, StreamSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST(basic_stream_socket)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 
@@ -177,15 +179,13 @@ class basic_stream_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_socket(io_service&) constructor.
+   * constructed using the @c basic_stream_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename StreamSocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   basic_stream_socket(
-      basic_stream_socket<Protocol1, StreamSocketService1>&& other,
+      basic_stream_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other,
       typename enable_if<is_convertible<Protocol1, Protocol>::value>::type* = 0)
-    : basic_socket<Protocol, StreamSocketService>(
-        BOOST_ASIO_MOVE_CAST2(basic_stream_socket<
-          Protocol1, StreamSocketService1>)(other))
+    : basic_socket<Protocol BOOST_ASIO_SVC_TARG>(std::move(other))
   {
   }
 
@@ -197,20 +197,27 @@ class basic_stream_socket
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_socket(io_service&) constructor.
+   * constructed using the @c basic_stream_socket(io_context&) constructor.
    */
-  template <typename Protocol1, typename StreamSocketService1>
+  template <typename Protocol1 BOOST_ASIO_SVC_TPARAM1>
   typename enable_if<is_convertible<Protocol1, Protocol>::value,
       basic_stream_socket>::type& operator=(
-        basic_stream_socket<Protocol1, StreamSocketService1>&& other)
+        basic_stream_socket<Protocol1 BOOST_ASIO_SVC_TARG1>&& other)
   {
-    basic_socket<Protocol, StreamSocketService>::operator=(
-        BOOST_ASIO_MOVE_CAST2(basic_stream_socket<
-          Protocol1, StreamSocketService1>)(other));
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>::operator=(std::move(other));
     return *this;
   }
 #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
+  /// Destroys the socket.
+  /**
+   * This function destroys the socket, cancelling any outstanding asynchronous
+   * operations associated with the socket as if by calling @c cancel.
+   */
+  ~basic_stream_socket()
+  {
+  }
+
   /// Send some data on the socket.
   /**
    * This function is used to send data on the stream socket. The function
@@ -330,7 +337,7 @@ class basic_stream_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The send operation may not transmit all of the data to the peer.
    * Consider using the @ref async_write function if you need to ensure that all
@@ -355,9 +362,20 @@ class basic_stream_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(
         this->get_implementation(), buffers, 0,
         BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(
+        this->get_implementation(), buffers, 0,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous send.
@@ -382,7 +400,7 @@ class basic_stream_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The send operation may not transmit all of the data to the peer.
    * Consider using the @ref async_write function if you need to ensure that all
@@ -408,9 +426,20 @@ class basic_stream_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(
         this->get_implementation(), buffers, flags,
         BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(
+        this->get_implementation(), buffers, flags,
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Receive some data on the socket.
@@ -538,7 +567,7 @@ class basic_stream_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The receive operation may not receive all of the requested number of
    * bytes. Consider using the @ref async_read function if you need to ensure
@@ -565,8 +594,18 @@ class basic_stream_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(this->get_implementation(),
         buffers, 0, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive(this->get_implementation(),
+        buffers, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Start an asynchronous receive.
@@ -591,7 +630,7 @@ class basic_stream_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The receive operation may not receive all of the requested number of
    * bytes. Consider using the @ref async_read function if you need to ensure
@@ -619,8 +658,18 @@ class basic_stream_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(this->get_implementation(),
         buffers, flags, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive(this->get_implementation(),
+        buffers, flags, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Write some data to the socket.
@@ -703,7 +752,7 @@ class basic_stream_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The write operation may not transmit all of the data to the peer.
    * Consider using the @ref async_write function if you need to ensure that all
@@ -728,8 +777,18 @@ class basic_stream_socket
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_send(this->get_implementation(),
         buffers, 0, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_send(this->get_implementation(),
+        buffers, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 
   /// Read some data from the socket.
@@ -815,7 +874,7 @@ class basic_stream_socket
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The read operation may not read all of the requested number of bytes.
    * Consider using the @ref async_read function if you need to ensure that the
@@ -841,8 +900,18 @@ class basic_stream_socket
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
     return this->get_service().async_receive(this->get_implementation(),
         buffers, 0, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_receive(this->get_implementation(),
+        buffers, 0, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 };
 
diff --git a/include/boost/asio/basic_streambuf.hpp b/include/boost/asio/basic_streambuf.hpp
index 1392596dc5..d8bfecd6b6 100644
--- a/include/boost/asio/basic_streambuf.hpp
+++ b/include/boost/asio/basic_streambuf.hpp
@@ -120,8 +120,8 @@ class basic_streambuf
   /// The type used to represent the output sequence as a list of buffers.
   typedef implementation_defined mutable_buffers_type;
 #else
-  typedef boost::asio::const_buffers_1 const_buffers_type;
-  typedef boost::asio::mutable_buffers_1 mutable_buffers_type;
+  typedef BOOST_ASIO_CONST_BUFFER const_buffers_type;
+  typedef BOOST_ASIO_MUTABLE_BUFFER mutable_buffers_type;
 #endif
 
   /// Construct a basic_streambuf object.
@@ -152,11 +152,11 @@ class basic_streambuf
    * while (i != bufs.end())
    * {
    *   const_buffer buf(*i++);
-   *   s += buffer_size(buf);
+   *   s += buf.size();
    * }
    * @endcode
    */
-  std::size_t size() const
+  std::size_t size() const BOOST_ASIO_NOEXCEPT
   {
     return pptr() - gptr();
   }
@@ -166,11 +166,21 @@ class basic_streambuf
    * @returns The allowed maximum of the sum of the sizes of the input sequence
    * and output sequence.
    */
-  std::size_t max_size() const
+  std::size_t max_size() const BOOST_ASIO_NOEXCEPT
   {
     return max_size_;
   }
 
+  /// Get the current capacity of the basic_streambuf.
+  /**
+   * @returns The current total capacity of the streambuf, i.e. for both the
+   * input sequence and output sequence.
+   */
+  std::size_t capacity() const BOOST_ASIO_NOEXCEPT
+  {
+    return buffer_.capacity();
+  }
+
   /// Get a list of buffers that represents the input sequence.
   /**
    * @returns An object of type @c const_buffers_type that satisfies
@@ -180,7 +190,7 @@ class basic_streambuf
    * @note The returned object is invalidated by any @c basic_streambuf member
    * function that modifies the input sequence or output sequence.
    */
-  const_buffers_type data() const
+  const_buffers_type data() const BOOST_ASIO_NOEXCEPT
   {
     return boost::asio::buffer(boost::asio::const_buffer(gptr(),
           (pptr() - gptr()) * sizeof(char_type)));
@@ -223,8 +233,7 @@ class basic_streambuf
    */
   void commit(std::size_t n)
   {
-    if (pptr() + n > epptr())
-      n = epptr() - pptr();
+    n = std::min<std::size_t>(n, epptr() - pptr());
     pbump(static_cast<int>(n));
     setg(eback(), gptr(), pptr());
   }
@@ -351,15 +360,89 @@ class basic_streambuf
   }
 };
 
-// Helper function to get the preferred size for reading data. Used for any
-// user-provided specialisations of basic_streambuf.
+/// Adapts basic_streambuf to the dynamic buffer sequence type requirements.
+#if defined(GENERATING_DOCUMENTATION)
+template <typename Allocator = std::allocator<char> >
+#else
 template <typename Allocator>
-inline std::size_t read_size_helper(
-    basic_streambuf<Allocator>& sb, std::size_t max_size)
+#endif
+class basic_streambuf_ref
 {
-  return std::min<std::size_t>(512,
-      std::min<std::size_t>(max_size, sb.max_size() - sb.size()));
-}
+public:
+  /// The type used to represent the input sequence as a list of buffers.
+  typedef typename basic_streambuf<Allocator>::const_buffers_type
+    const_buffers_type;
+
+  /// The type used to represent the output sequence as a list of buffers.
+  typedef typename basic_streambuf<Allocator>::mutable_buffers_type
+    mutable_buffers_type;
+
+  /// Construct a basic_streambuf_ref for the given basic_streambuf object.
+  explicit basic_streambuf_ref(basic_streambuf<Allocator>& sb)
+    : sb_(sb)
+  {
+  }
+
+  /// Copy construct a basic_streambuf_ref.
+  basic_streambuf_ref(const basic_streambuf_ref& other) BOOST_ASIO_NOEXCEPT
+    : sb_(other.sb_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move construct a basic_streambuf_ref.
+  basic_streambuf_ref(basic_streambuf_ref&& other) BOOST_ASIO_NOEXCEPT
+    : sb_(other.sb_)
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Get the size of the input sequence.
+  std::size_t size() const BOOST_ASIO_NOEXCEPT
+  {
+    return sb_.size();
+  }
+
+  /// Get the maximum size of the dynamic buffer.
+  std::size_t max_size() const BOOST_ASIO_NOEXCEPT
+  {
+    return sb_.max_size();
+  }
+
+  /// Get the current capacity of the dynamic buffer.
+  std::size_t capacity() const BOOST_ASIO_NOEXCEPT
+  {
+    return sb_.capacity();
+  }
+
+  /// Get a list of buffers that represents the input sequence.
+  const_buffers_type data() const BOOST_ASIO_NOEXCEPT
+  {
+    return sb_.data();
+  }
+
+  /// Get a list of buffers that represents the output sequence, with the given
+  /// size.
+  mutable_buffers_type prepare(std::size_t n)
+  {
+    return sb_.prepare(n);
+  }
+
+  /// Move bytes from the output sequence to the input sequence.
+  void commit(std::size_t n)
+  {
+    return sb_.commit(n);
+  }
+
+  /// Remove characters from the input sequence.
+  void consume(std::size_t n)
+  {
+    return sb_.consume(n);
+  }
+
+private:
+  basic_streambuf<Allocator>& sb_;
+};
 
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/basic_streambuf_fwd.hpp b/include/boost/asio/basic_streambuf_fwd.hpp
index f3e006bf11..b34e3459bb 100644
--- a/include/boost/asio/basic_streambuf_fwd.hpp
+++ b/include/boost/asio/basic_streambuf_fwd.hpp
@@ -27,6 +27,9 @@ namespace asio {
 template <typename Allocator = std::allocator<char> >
 class basic_streambuf;
 
+template <typename Allocator = std::allocator<char> >
+class basic_streambuf_ref;
+
 } // namespace asio
 } // namespace boost
 
diff --git a/include/boost/asio/basic_waitable_timer.hpp b/include/boost/asio/basic_waitable_timer.hpp
index e4aeb0b7d8..3657d8b429 100644
--- a/include/boost/asio/basic_waitable_timer.hpp
+++ b/include/boost/asio/basic_waitable_timer.hpp
@@ -22,13 +22,37 @@
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
 #include <boost/asio/wait_traits.hpp>
-#include <boost/asio/waitable_timer_service.hpp>
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/waitable_timer_service.hpp>
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/detail/chrono_time_traits.hpp>
+# include <boost/asio/detail/deadline_timer_service.hpp>
+# define BOOST_ASIO_SVC_T \
+    detail::deadline_timer_service< \
+      detail::chrono_time_traits<Clock, WaitTraits> >
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
+#if !defined(BOOST_ASIO_BASIC_WAITABLE_TIMER_FWD_DECL)
+#define BOOST_ASIO_BASIC_WAITABLE_TIMER_FWD_DECL
+
+// Forward declaration with defaulted arguments.
+template <typename Clock,
+    typename WaitTraits = boost::asio::wait_traits<Clock>
+    BOOST_ASIO_SVC_TPARAM_DEF2(= waitable_timer_service<Clock, WaitTraits>)>
+class basic_waitable_timer;
+
+#endif // !defined(BOOST_ASIO_BASIC_WAITABLE_TIMER_FWD_DECL)
+
 /// Provides waitable timer functionality.
 /**
  * The basic_waitable_timer class template provides the ability to perform a
@@ -52,10 +76,10 @@ namespace asio {
  * Performing a blocking wait (C++11):
  * @code
  * // Construct a timer without setting an expiry time.
- * boost::asio::steady_timer timer(io_service);
+ * boost::asio::steady_timer timer(io_context);
  *
  * // Set an expiry time relative to now.
- * timer.expires_from_now(std::chrono::seconds(5));
+ * timer.expires_after(std::chrono::seconds(5));
  *
  * // Wait for the timer to expire.
  * timer.wait();
@@ -75,7 +99,7 @@ namespace asio {
  * ...
  *
  * // Construct a timer with an absolute expiry time.
- * boost::asio::steady_timer timer(io_service,
+ * boost::asio::steady_timer timer(io_context,
  *     std::chrono::steady_clock::now() + std::chrono::seconds(60));
  *
  * // Start an asynchronous wait.
@@ -92,7 +116,7 @@ namespace asio {
  * @code
  * void on_some_event()
  * {
- *   if (my_timer.expires_from_now(seconds(5)) > 0)
+ *   if (my_timer.expires_after(seconds(5)) > 0)
  *   {
  *     // We managed to cancel the timer. Start new asynchronous wait.
  *     my_timer.async_wait(on_timeout);
@@ -112,7 +136,7 @@ namespace asio {
  * }
  * @endcode
  *
- * @li The boost::asio::basic_waitable_timer::expires_from_now() function
+ * @li The boost::asio::basic_waitable_timer::expires_after() function
  * cancels any pending asynchronous waits, and returns the number of
  * asynchronous waits that were cancelled. If it returns 0 then you were too
  * late and the wait handler has already been executed, or will soon be
@@ -121,13 +145,14 @@ namespace asio {
  * @li If a wait handler is cancelled, the boost::system::error_code passed to
  * it contains the value boost::asio::error::operation_aborted.
  */
-template <typename Clock,
-    typename WaitTraits = boost::asio::wait_traits<Clock>,
-    typename WaitableTimerService = waitable_timer_service<Clock, WaitTraits> >
+template <typename Clock, typename WaitTraits BOOST_ASIO_SVC_TPARAM>
 class basic_waitable_timer
-  : public basic_io_object<WaitableTimerService>
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>
 {
 public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
   /// The clock type.
   typedef Clock clock_type;
 
@@ -143,14 +168,14 @@ class basic_waitable_timer
   /// Constructor.
   /**
    * This constructor creates a timer without setting an expiry time. The
-   * expires_at() or expires_from_now() functions must be called to set an
-   * expiry time before the timer can be waited on.
+   * expires_at() or expires_after() functions must be called to set an expiry
+   * time before the timer can be waited on.
    *
-   * @param io_service The io_service object that the timer will use to dispatch
+   * @param io_context The io_context object that the timer will use to dispatch
    * handlers for any asynchronous operations performed on the timer.
    */
-  explicit basic_waitable_timer(boost::asio::io_service& io_service)
-    : basic_io_object<WaitableTimerService>(io_service)
+  explicit basic_waitable_timer(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
   }
 
@@ -158,18 +183,18 @@ class basic_waitable_timer
   /**
    * This constructor creates a timer and sets the expiry time.
    *
-   * @param io_service The io_service object that the timer will use to dispatch
+   * @param io_context The io_context object that the timer will use to dispatch
    * handlers for any asynchronous operations performed on the timer.
    *
    * @param expiry_time The expiry time to be used for the timer, expressed
    * as an absolute time.
    */
-  basic_waitable_timer(boost::asio::io_service& io_service,
+  basic_waitable_timer(boost::asio::io_context& io_context,
       const time_point& expiry_time)
-    : basic_io_object<WaitableTimerService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
-    this->service.expires_at(this->implementation, expiry_time, ec);
+    this->get_service().expires_at(this->get_implementation(), expiry_time, ec);
     boost::asio::detail::throw_error(ec, "expires_at");
   }
 
@@ -177,21 +202,105 @@ class basic_waitable_timer
   /**
    * This constructor creates a timer and sets the expiry time.
    *
-   * @param io_service The io_service object that the timer will use to dispatch
+   * @param io_context The io_context object that the timer will use to dispatch
    * handlers for any asynchronous operations performed on the timer.
    *
    * @param expiry_time The expiry time to be used for the timer, relative to
    * now.
    */
-  basic_waitable_timer(boost::asio::io_service& io_service,
+  basic_waitable_timer(boost::asio::io_context& io_context,
       const duration& expiry_time)
-    : basic_io_object<WaitableTimerService>(io_service)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
   {
     boost::system::error_code ec;
-    this->service.expires_from_now(this->implementation, expiry_time, ec);
-    boost::asio::detail::throw_error(ec, "expires_from_now");
+    this->get_service().expires_after(
+        this->get_implementation(), expiry_time, ec);
+    boost::asio::detail::throw_error(ec, "expires_after");
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a basic_waitable_timer from another.
+  /**
+   * This constructor moves a timer from one object to another.
+   *
+   * @param other The other basic_waitable_timer object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c basic_waitable_timer(io_context&) constructor.
+   */
+  basic_waitable_timer(basic_waitable_timer&& other)
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
+  {
+  }
+
+  /// Move-assign a basic_waitable_timer from another.
+  /**
+   * This assignment operator moves a timer from one object to another. Cancels
+   * any outstanding asynchronous operations associated with the target object.
+   *
+   * @param other The other basic_waitable_timer object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c basic_waitable_timer(io_context&) constructor.
+   */
+  basic_waitable_timer& operator=(basic_waitable_timer&& other)
+  {
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Destroys the timer.
+  /**
+   * This function destroys the timer, cancelling any outstanding asynchronous
+   * wait operations associated with the timer as if by calling @c cancel.
+   */
+  ~basic_waitable_timer()
+  {
+  }
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  // These functions are provided by basic_io_object<>.
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
   }
 
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
   /// Cancel any asynchronous operations that are waiting on the timer.
   /**
    * This function forces the completion of any pending asynchronous wait
@@ -217,12 +326,14 @@ class basic_waitable_timer
   std::size_t cancel()
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.cancel(this->implementation, ec);
+    std::size_t s = this->get_service().cancel(this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "cancel");
     return s;
   }
 
-  /// Cancel any asynchronous operations that are waiting on the timer.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use non-error_code overload.) Cancel any asynchronous
+  /// operations that are waiting on the timer.
   /**
    * This function forces the completion of any pending asynchronous wait
    * operations against the timer. The handler for each cancelled operation will
@@ -246,8 +357,9 @@ class basic_waitable_timer
    */
   std::size_t cancel(boost::system::error_code& ec)
   {
-    return this->service.cancel(this->implementation, ec);
+    return this->get_service().cancel(this->get_implementation(), ec);
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Cancels one asynchronous operation that is waiting on the timer.
   /**
@@ -276,12 +388,15 @@ class basic_waitable_timer
   std::size_t cancel_one()
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.cancel_one(this->implementation, ec);
+    std::size_t s = this->get_service().cancel_one(
+        this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "cancel_one");
     return s;
   }
 
-  /// Cancels one asynchronous operation that is waiting on the timer.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use non-error_code overload.) Cancels one asynchronous
+  /// operation that is waiting on the timer.
   /**
    * This function forces the completion of one pending asynchronous wait
    * operation against the timer. Handlers are cancelled in FIFO order. The
@@ -307,17 +422,29 @@ class basic_waitable_timer
    */
   std::size_t cancel_one(boost::system::error_code& ec)
   {
-    return this->service.cancel_one(this->implementation, ec);
+    return this->get_service().cancel_one(this->get_implementation(), ec);
   }
 
-  /// Get the timer's expiry time as an absolute time.
+  /// (Deprecated: Use expiry().) Get the timer's expiry time as an absolute
+  /// time.
   /**
    * This function may be used to obtain the timer's current expiry time.
    * Whether the timer has expired or not does not affect this value.
    */
   time_point expires_at() const
   {
-    return this->service.expires_at(this->implementation);
+    return this->get_service().expires_at(this->get_implementation());
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the timer's expiry time as an absolute time.
+  /**
+   * This function may be used to obtain the timer's current expiry time.
+   * Whether the timer has expired or not does not affect this value.
+   */
+  time_point expiry() const
+  {
+    return this->get_service().expiry(this->get_implementation());
   }
 
   /// Set the timer's expiry time as an absolute time.
@@ -345,13 +472,15 @@ class basic_waitable_timer
   std::size_t expires_at(const time_point& expiry_time)
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.expires_at(
-        this->implementation, expiry_time, ec);
+    std::size_t s = this->get_service().expires_at(
+        this->get_implementation(), expiry_time, ec);
     boost::asio::detail::throw_error(ec, "expires_at");
     return s;
   }
 
-  /// Set the timer's expiry time as an absolute time.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use non-error_code overload.) Set the timer's expiry time as
+  /// an absolute time.
   /**
    * This function sets the expiry time. Any pending asynchronous wait
    * operations will be cancelled. The handler for each cancelled operation will
@@ -376,20 +505,55 @@ class basic_waitable_timer
   std::size_t expires_at(const time_point& expiry_time,
       boost::system::error_code& ec)
   {
-    return this->service.expires_at(this->implementation, expiry_time, ec);
+    return this->get_service().expires_at(
+        this->get_implementation(), expiry_time, ec);
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-  /// Get the timer's expiry time relative to now.
+  /// Set the timer's expiry time relative to now.
+  /**
+   * This function sets the expiry time. Any pending asynchronous wait
+   * operations will be cancelled. The handler for each cancelled operation will
+   * be invoked with the boost::asio::error::operation_aborted error code.
+   *
+   * @param expiry_time The expiry time to be used for the timer.
+   *
+   * @return The number of asynchronous operations that were cancelled.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note If the timer has already expired when expires_after() is called,
+   * then the handlers for asynchronous wait operations will:
+   *
+   * @li have already been invoked; or
+   *
+   * @li have been queued for invocation in the near future.
+   *
+   * These handlers can no longer be cancelled, and therefore are passed an
+   * error code that indicates the successful completion of the wait operation.
+   */
+  std::size_t expires_after(const duration& expiry_time)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().expires_after(
+        this->get_implementation(), expiry_time, ec);
+    boost::asio::detail::throw_error(ec, "expires_after");
+    return s;
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use expiry().) Get the timer's expiry time relative to now.
   /**
    * This function may be used to obtain the timer's current expiry time.
    * Whether the timer has expired or not does not affect this value.
    */
   duration expires_from_now() const
   {
-    return this->service.expires_from_now(this->implementation);
+    return this->get_service().expires_from_now(this->get_implementation());
   }
 
-  /// Set the timer's expiry time relative to now.
+  /// (Deprecated: Use expires_after().) Set the timer's expiry time relative
+  /// to now.
   /**
    * This function sets the expiry time. Any pending asynchronous wait
    * operations will be cancelled. The handler for each cancelled operation will
@@ -414,13 +578,14 @@ class basic_waitable_timer
   std::size_t expires_from_now(const duration& expiry_time)
   {
     boost::system::error_code ec;
-    std::size_t s = this->service.expires_from_now(
-        this->implementation, expiry_time, ec);
+    std::size_t s = this->get_service().expires_from_now(
+        this->get_implementation(), expiry_time, ec);
     boost::asio::detail::throw_error(ec, "expires_from_now");
     return s;
   }
 
-  /// Set the timer's expiry time relative to now.
+  /// (Deprecated: Use expires_after().) Set the timer's expiry time relative
+  /// to now.
   /**
    * This function sets the expiry time. Any pending asynchronous wait
    * operations will be cancelled. The handler for each cancelled operation will
@@ -445,9 +610,10 @@ class basic_waitable_timer
   std::size_t expires_from_now(const duration& expiry_time,
       boost::system::error_code& ec)
   {
-    return this->service.expires_from_now(
-        this->implementation, expiry_time, ec);
+    return this->get_service().expires_from_now(
+        this->get_implementation(), expiry_time, ec);
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Perform a blocking wait on the timer.
   /**
@@ -459,7 +625,7 @@ class basic_waitable_timer
   void wait()
   {
     boost::system::error_code ec;
-    this->service.wait(this->implementation, ec);
+    this->get_service().wait(this->get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "wait");
   }
 
@@ -472,7 +638,7 @@ class basic_waitable_timer
    */
   void wait(boost::system::error_code& ec)
   {
-    this->service.wait(this->implementation, ec);
+    this->get_service().wait(this->get_implementation(), ec);
   }
 
   /// Start an asynchronous wait on the timer.
@@ -497,7 +663,7 @@ class basic_waitable_timer
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename WaitHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
@@ -508,9 +674,25 @@ class basic_waitable_timer
     // not meet the documented type requirements for a WaitHandler.
     BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
 
-    return this->service.async_wait(this->implementation,
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_wait(this->get_implementation(),
         BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_wait(this->get_implementation(),
+        init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
+
+private:
+  // Disallow copying and assignment.
+  basic_waitable_timer(const basic_waitable_timer&) BOOST_ASIO_DELETED;
+  basic_waitable_timer& operator=(
+      const basic_waitable_timer&) BOOST_ASIO_DELETED;
 };
 
 } // namespace asio
@@ -518,4 +700,8 @@ class basic_waitable_timer
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# undef BOOST_ASIO_SVC_T
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_BASIC_WAITABLE_TIMER_HPP
diff --git a/include/boost/asio/bind_executor.hpp b/include/boost/asio/bind_executor.hpp
new file mode 100644
index 0000000000..f6db65fc91
--- /dev/null
+++ b/include/boost/asio/bind_executor.hpp
@@ -0,0 +1,613 @@
+//
+// bind_executor.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_BIND_EXECUTOR_HPP
+#define BOOST_ASIO_BIND_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/detail/variadic_templates.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/execution_context.hpp>
+#include <boost/asio/is_executor.hpp>
+#include <boost/asio/uses_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T>
+struct executor_binder_check
+{
+  typedef void type;
+};
+
+// Helper to automatically define nested typedef result_type.
+
+template <typename T, typename = void>
+struct executor_binder_result_type
+{
+protected:
+  typedef void result_type_or_void;
+};
+
+template <typename T>
+struct executor_binder_result_type<T,
+  typename executor_binder_check<typename T::result_type>::type>
+{
+  typedef typename T::result_type result_type;
+protected:
+  typedef result_type result_type_or_void;
+};
+
+template <typename R>
+struct executor_binder_result_type<R(*)()>
+{
+  typedef R result_type;
+protected:
+  typedef result_type result_type_or_void;
+};
+
+template <typename R>
+struct executor_binder_result_type<R(&)()>
+{
+  typedef R result_type;
+protected:
+  typedef result_type result_type_or_void;
+};
+
+template <typename R, typename A1>
+struct executor_binder_result_type<R(*)(A1)>
+{
+  typedef R result_type;
+protected:
+  typedef result_type result_type_or_void;
+};
+
+template <typename R, typename A1>
+struct executor_binder_result_type<R(&)(A1)>
+{
+  typedef R result_type;
+protected:
+  typedef result_type result_type_or_void;
+};
+
+template <typename R, typename A1, typename A2>
+struct executor_binder_result_type<R(*)(A1, A2)>
+{
+  typedef R result_type;
+protected:
+  typedef result_type result_type_or_void;
+};
+
+template <typename R, typename A1, typename A2>
+struct executor_binder_result_type<R(&)(A1, A2)>
+{
+  typedef R result_type;
+protected:
+  typedef result_type result_type_or_void;
+};
+
+// Helper to automatically define nested typedef argument_type.
+
+template <typename T, typename = void>
+struct executor_binder_argument_type {};
+
+template <typename T>
+struct executor_binder_argument_type<T,
+  typename executor_binder_check<typename T::argument_type>::type>
+{
+  typedef typename T::argument_type argument_type;
+};
+
+template <typename R, typename A1>
+struct executor_binder_argument_type<R(*)(A1)>
+{
+  typedef A1 argument_type;
+};
+
+template <typename R, typename A1>
+struct executor_binder_argument_type<R(&)(A1)>
+{
+  typedef A1 argument_type;
+};
+
+// Helper to automatically define nested typedefs first_argument_type and
+// second_argument_type.
+
+template <typename T, typename = void>
+struct executor_binder_argument_types {};
+
+template <typename T>
+struct executor_binder_argument_types<T,
+  typename executor_binder_check<typename T::first_argument_type>::type>
+{
+  typedef typename T::first_argument_type first_argument_type;
+  typedef typename T::second_argument_type second_argument_type;
+};
+
+template <typename R, typename A1, typename A2>
+struct executor_binder_argument_type<R(*)(A1, A2)>
+{
+  typedef A1 first_argument_type;
+  typedef A2 second_argument_type;
+};
+
+template <typename R, typename A1, typename A2>
+struct executor_binder_argument_type<R(&)(A1, A2)>
+{
+  typedef A1 first_argument_type;
+  typedef A2 second_argument_type;
+};
+
+// Helper to:
+// - Apply the empty base optimisation to the executor.
+// - Perform uses_executor construction of the target type, if required.
+
+template <typename T, typename Executor, bool UsesExecutor>
+class executor_binder_base;
+
+template <typename T, typename Executor>
+class executor_binder_base<T, Executor, true>
+  : protected Executor
+{
+protected:
+  template <typename E, typename U>
+  executor_binder_base(BOOST_ASIO_MOVE_ARG(E) e, BOOST_ASIO_MOVE_ARG(U) u)
+    : executor_(BOOST_ASIO_MOVE_CAST(E)(e)),
+      target_(executor_arg_t(), executor_, BOOST_ASIO_MOVE_CAST(U)(u))
+  {
+  }
+
+  Executor executor_;
+  T target_;
+};
+
+template <typename T, typename Executor>
+class executor_binder_base<T, Executor, false>
+{
+protected:
+  template <typename E, typename U>
+  executor_binder_base(BOOST_ASIO_MOVE_ARG(E) e, BOOST_ASIO_MOVE_ARG(U) u)
+    : executor_(BOOST_ASIO_MOVE_CAST(E)(e)),
+      target_(BOOST_ASIO_MOVE_CAST(U)(u))
+  {
+  }
+
+  Executor executor_;
+  T target_;
+};
+
+// Helper to enable SFINAE on zero-argument operator() below.
+
+template <typename T, typename = void>
+struct executor_binder_result_of0
+{
+  typedef void type;
+};
+
+template <typename T>
+struct executor_binder_result_of0<T,
+  typename executor_binder_check<typename result_of<T()>::type>::type>
+{
+  typedef typename result_of<T()>::type type;
+};
+
+} // namespace detail
+
+/// A call wrapper type to bind an executor of type @c Executor to an object of
+/// type @c T.
+template <typename T, typename Executor>
+class executor_binder
+#if !defined(GENERATING_DOCUMENTATION)
+  : public detail::executor_binder_result_type<T>,
+    public detail::executor_binder_argument_type<T>,
+    public detail::executor_binder_argument_types<T>,
+    private detail::executor_binder_base<
+      T, Executor, uses_executor<T, Executor>::value>
+#endif // !defined(GENERATING_DOCUMENTATION)
+{
+public:
+  /// The type of the target object.
+  typedef T target_type;
+
+  /// The type of the associated executor.
+  typedef Executor executor_type;
+
+#if defined(GENERATING_DOCUMENTATION)
+  /// The return type if a function.
+  /**
+   * The type of @c result_type is based on the type @c T of the wrapper's
+   * target object:
+   *
+   * @li if @c T is a pointer to function type, @c result_type is a synonym for
+   * the return type of @c T;
+   *
+   * @li if @c T is a class type with a member type @c result_type, then @c
+   * result_type is a synonym for @c T::result_type;
+   *
+   * @li otherwise @c result_type is not defined.
+   */
+  typedef see_below result_type;
+
+  /// The type of the function's argument.
+  /**
+   * The type of @c argument_type is based on the type @c T of the wrapper's
+   * target object:
+   *
+   * @li if @c T is a pointer to a function type accepting a single argument,
+   * @c argument_type is a synonym for the return type of @c T;
+   *
+   * @li if @c T is a class type with a member type @c argument_type, then @c
+   * argument_type is a synonym for @c T::argument_type;
+   *
+   * @li otherwise @c argument_type is not defined.
+   */
+  typedef see_below argument_type;
+
+  /// The type of the function's first argument.
+  /**
+   * The type of @c first_argument_type is based on the type @c T of the
+   * wrapper's target object:
+   *
+   * @li if @c T is a pointer to a function type accepting two arguments, @c
+   * first_argument_type is a synonym for the return type of @c T;
+   *
+   * @li if @c T is a class type with a member type @c first_argument_type,
+   * then @c first_argument_type is a synonym for @c T::first_argument_type;
+   *
+   * @li otherwise @c first_argument_type is not defined.
+   */
+  typedef see_below first_argument_type;
+
+  /// The type of the function's second argument.
+  /**
+   * The type of @c second_argument_type is based on the type @c T of the
+   * wrapper's target object:
+   *
+   * @li if @c T is a pointer to a function type accepting two arguments, @c
+   * second_argument_type is a synonym for the return type of @c T;
+   *
+   * @li if @c T is a class type with a member type @c first_argument_type,
+   * then @c second_argument_type is a synonym for @c T::second_argument_type;
+   *
+   * @li otherwise @c second_argument_type is not defined.
+   */
+  typedef see_below second_argument_type;
+#endif // defined(GENERATING_DOCUMENTATION)
+
+  /// Construct an executor wrapper for the specified object.
+  /**
+   * This constructor is only valid if the type @c T is constructible from type
+   * @c U.
+   */
+  template <typename U>
+  executor_binder(executor_arg_t, const executor_type& e,
+      BOOST_ASIO_MOVE_ARG(U) u)
+    : base_type(e, BOOST_ASIO_MOVE_CAST(U)(u))
+  {
+  }
+
+  /// Copy constructor.
+  executor_binder(const executor_binder& other)
+    : base_type(other.get_executor(), other.get())
+  {
+  }
+
+  /// Construct a copy, but specify a different executor.
+  executor_binder(executor_arg_t, const executor_type& e,
+      const executor_binder& other)
+    : base_type(e, other.get())
+  {
+  }
+
+  /// Construct a copy of a different executor wrapper type.
+  /**
+   * This constructor is only valid if the @c Executor type is constructible
+   * from type @c OtherExecutor, and the type @c T is constructible from type
+   * @c U.
+   */
+  template <typename U, typename OtherExecutor>
+  executor_binder(const executor_binder<U, OtherExecutor>& other)
+    : base_type(other.get_executor(), other.get())
+  {
+  }
+
+  /// Construct a copy of a different executor wrapper type, but specify a
+  /// different executor.
+  /**
+   * This constructor is only valid if the type @c T is constructible from type
+   * @c U.
+   */
+  template <typename U, typename OtherExecutor>
+  executor_binder(executor_arg_t, const executor_type& e,
+      const executor_binder<U, OtherExecutor>& other)
+    : base_type(e, other.get())
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Move constructor.
+  executor_binder(executor_binder&& other)
+    : base_type(BOOST_ASIO_MOVE_CAST(executor_type)(other.get_executor()),
+        BOOST_ASIO_MOVE_CAST(T)(other.get()))
+  {
+  }
+
+  /// Move construct the target object, but specify a different executor.
+  executor_binder(executor_arg_t, const executor_type& e,
+      executor_binder&& other)
+    : base_type(e, BOOST_ASIO_MOVE_CAST(T)(other.get()))
+  {
+  }
+
+  /// Move construct from a different executor wrapper type.
+  template <typename U, typename OtherExecutor>
+  executor_binder(executor_binder<U, OtherExecutor>&& other)
+    : base_type(BOOST_ASIO_MOVE_CAST(OtherExecutor)(other.get_executor()),
+        BOOST_ASIO_MOVE_CAST(U)(other.get()))
+  {
+  }
+
+  /// Move construct from a different executor wrapper type, but specify a
+  /// different executor.
+  template <typename U, typename OtherExecutor>
+  executor_binder(executor_arg_t, const executor_type& e,
+      executor_binder<U, OtherExecutor>&& other)
+    : base_type(e, BOOST_ASIO_MOVE_CAST(U)(other.get()))
+  {
+  }
+
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Destructor.
+  ~executor_binder()
+  {
+  }
+
+  /// Obtain a reference to the target object.
+  target_type& get() BOOST_ASIO_NOEXCEPT
+  {
+    return this->target_;
+  }
+
+  /// Obtain a reference to the target object.
+  const target_type& get() const BOOST_ASIO_NOEXCEPT
+  {
+    return this->target_;
+  }
+
+  /// Obtain the associated executor.
+  executor_type get_executor() const BOOST_ASIO_NOEXCEPT
+  {
+    return this->executor_;
+  }
+
+#if defined(GENERATING_DOCUMENTATION)
+
+  template <typename... Args> auto operator()(Args&& ...);
+  template <typename... Args> auto operator()(Args&& ...) const;
+
+#elif defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  /// Forwarding function call operator.
+  template <typename... Args>
+  typename result_of<T(Args...)>::type operator()(
+      BOOST_ASIO_MOVE_ARG(Args)... args)
+  {
+    return this->target_(BOOST_ASIO_MOVE_CAST(Args)(args)...);
+  }
+
+  /// Forwarding function call operator.
+  template <typename... Args>
+  typename result_of<T(Args...)>::type operator()(
+      BOOST_ASIO_MOVE_ARG(Args)... args) const
+  {
+    return this->target_(BOOST_ASIO_MOVE_CAST(Args)(args)...);
+  }
+
+#elif defined(BOOST_ASIO_HAS_STD_TYPE_TRAITS) && !defined(_MSC_VER)
+
+  typename detail::executor_binder_result_of0<T>::type operator()()
+  {
+    return this->target_();
+  }
+
+  typename detail::executor_binder_result_of0<T>::type operator()() const
+  {
+    return this->target_();
+  }
+
+#define BOOST_ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF(n) \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  typename result_of<T(BOOST_ASIO_VARIADIC_TARGS(n))>::type operator()( \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    return this->target_(BOOST_ASIO_VARIADIC_MOVE_ARGS(n)); \
+  } \
+  \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  typename result_of<T(BOOST_ASIO_VARIADIC_TARGS(n))>::type operator()( \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) const \
+  { \
+    return this->target_(BOOST_ASIO_VARIADIC_MOVE_ARGS(n)); \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF)
+#undef BOOST_ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF
+
+#else // defined(BOOST_ASIO_HAS_STD_TYPE_TRAITS) && !defined(_MSC_VER)
+
+  typedef typename detail::executor_binder_result_type<T>::result_type_or_void
+    result_type_or_void;
+
+  result_type_or_void operator()()
+  {
+    return this->target_();
+  }
+
+  result_type_or_void operator()() const
+  {
+    return this->target_();
+  }
+
+#define BOOST_ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF(n) \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  result_type_or_void operator()( \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    return this->target_(BOOST_ASIO_VARIADIC_MOVE_ARGS(n)); \
+  } \
+  \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  result_type_or_void operator()( \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) const \
+  { \
+    return this->target_(BOOST_ASIO_VARIADIC_MOVE_ARGS(n)); \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF)
+#undef BOOST_ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF
+
+#endif // defined(BOOST_ASIO_HAS_STD_TYPE_TRAITS) && !defined(_MSC_VER)
+
+private:
+  typedef detail::executor_binder_base<T, Executor,
+    uses_executor<T, Executor>::value> base_type;
+};
+
+/// Associate an object of type @c T with an executor of type @c Executor.
+template <typename Executor, typename T>
+inline executor_binder<typename decay<T>::type, Executor>
+bind_executor(const Executor& ex, BOOST_ASIO_MOVE_ARG(T) t,
+    typename enable_if<is_executor<Executor>::value>::type* = 0)
+{
+  return executor_binder<typename decay<T>::type, Executor>(
+      executor_arg_t(), ex, BOOST_ASIO_MOVE_CAST(T)(t));
+}
+
+/// Associate an object of type @c T with an execution context's executor.
+template <typename ExecutionContext, typename T>
+inline executor_binder<typename decay<T>::type,
+  typename ExecutionContext::executor_type>
+bind_executor(ExecutionContext& ctx, BOOST_ASIO_MOVE_ARG(T) t,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type* = 0)
+{
+  return executor_binder<typename decay<T>::type,
+    typename ExecutionContext::executor_type>(
+      executor_arg_t(), ctx.get_executor(), BOOST_ASIO_MOVE_CAST(T)(t));
+}
+
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename T, typename Executor>
+struct uses_executor<executor_binder<T, Executor>, Executor>
+  : true_type {};
+
+template <typename T, typename Executor, typename Signature>
+class async_result<executor_binder<T, Executor>, Signature>
+{
+public:
+  typedef executor_binder<
+    typename async_result<T, Signature>::completion_handler_type, Executor>
+      completion_handler_type;
+
+  typedef typename async_result<T, Signature>::return_type return_type;
+
+  explicit async_result(executor_binder<T, Executor>& b)
+    : target_(b.get())
+  {
+  }
+
+  return_type get()
+  {
+    return target_.get();
+  }
+
+private:
+  async_result(const async_result&) BOOST_ASIO_DELETED;
+  async_result& operator=(const async_result&) BOOST_ASIO_DELETED;
+
+  async_result<T, Signature> target_;
+};
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+template <typename T, typename Executor, typename Signature>
+struct handler_type<executor_binder<T, Executor>, Signature>
+{
+  typedef executor_binder<
+    typename handler_type<T, Signature>::type, Executor> type;
+};
+
+template <typename T, typename Executor>
+class async_result<executor_binder<T, Executor> >
+{
+public:
+  typedef typename async_result<T>::type type;
+
+  explicit async_result(executor_binder<T, Executor>& b)
+    : target_(b.get())
+  {
+  }
+
+  type get()
+  {
+    return target_.get();
+  }
+
+private:
+  async_result<T> target_;
+};
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+template <typename T, typename Executor, typename Allocator>
+struct associated_allocator<executor_binder<T, Executor>, Allocator>
+{
+  typedef typename associated_allocator<T, Allocator>::type type;
+
+  static type get(const executor_binder<T, Executor>& b,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<T, Allocator>::get(b.get(), a);
+  }
+};
+
+template <typename T, typename Executor, typename Executor1>
+struct associated_executor<executor_binder<T, Executor>, Executor1>
+{
+  typedef Executor type;
+
+  static type get(const executor_binder<T, Executor>& b,
+      const Executor1& = Executor1()) BOOST_ASIO_NOEXCEPT
+  {
+    return b.get_executor();
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_BIND_EXECUTOR_HPP
diff --git a/include/boost/asio/buffer.hpp b/include/boost/asio/buffer.hpp
index 700654d21d..fbd4126d42 100644
--- a/include/boost/asio/buffer.hpp
+++ b/include/boost/asio/buffer.hpp
@@ -18,9 +18,15 @@
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
 #include <cstring>
+#include <limits>
+#include <stdexcept>
 #include <string>
 #include <vector>
 #include <boost/asio/detail/array_fwd.hpp>
+#include <boost/asio/detail/is_buffer_sequence.hpp>
+#include <boost/asio/detail/string_view.hpp>
+#include <boost/asio/detail/throw_exception.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 
 #if defined(BOOST_ASIO_MSVC)
 # if defined(_HAS_ITERATOR_DEBUGGING) && (_HAS_ITERATOR_DEBUGGING != 0)
@@ -39,7 +45,7 @@
 #endif // defined(__GNUC__)
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-# include <boost/asio/detail/function.hpp>
+# include <boost/asio/detail/functional.hpp>
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
 
 #if defined(BOOST_ASIO_HAS_BOOST_WORKAROUND)
@@ -63,13 +69,6 @@ namespace asio {
 class mutable_buffer;
 class const_buffer;
 
-namespace detail {
-void* buffer_cast_helper(const mutable_buffer&);
-const void* buffer_cast_helper(const const_buffer&);
-std::size_t buffer_size_helper(const mutable_buffer&);
-std::size_t buffer_size_helper(const const_buffer&);
-} // namespace detail
-
 /// Holds a buffer that can be modified.
 /**
  * The mutable_buffer class provides a safe representation of a buffer that can
@@ -78,29 +77,29 @@ std::size_t buffer_size_helper(const const_buffer&);
  *
  * @par Accessing Buffer Contents
  *
- * The contents of a buffer may be accessed using the @ref buffer_size
- * and @ref buffer_cast functions:
+ * The contents of a buffer may be accessed using the @c data() and @c size()
+ * member functions:
  *
  * @code boost::asio::mutable_buffer b1 = ...;
- * std::size_t s1 = boost::asio::buffer_size(b1);
- * unsigned char* p1 = boost::asio::buffer_cast<unsigned char*>(b1);
+ * std::size_t s1 = b1.size();
+ * unsigned char* p1 = static_cast<unsigned char*>(b1.data());
  * @endcode
  *
- * The boost::asio::buffer_cast function permits violations of type safety, so
- * uses of it in application code should be carefully considered.
+ * The @c data() member function permits violations of type safety, so uses of
+ * it in application code should be carefully considered.
  */
 class mutable_buffer
 {
 public:
   /// Construct an empty buffer.
-  mutable_buffer()
+  mutable_buffer() BOOST_ASIO_NOEXCEPT
     : data_(0),
       size_(0)
   {
   }
 
   /// Construct a buffer to represent a given memory range.
-  mutable_buffer(void* data, std::size_t size)
+  mutable_buffer(void* data, std::size_t size) BOOST_ASIO_NOEXCEPT
     : data_(data),
       size_(size)
   {
@@ -121,12 +120,32 @@ class mutable_buffer
   }
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
 
-private:
-  friend void* boost::asio::detail::buffer_cast_helper(
-      const mutable_buffer& b);
-  friend std::size_t boost::asio::detail::buffer_size_helper(
-      const mutable_buffer& b);
+  /// Get a pointer to the beginning of the memory range.
+  void* data() const BOOST_ASIO_NOEXCEPT
+  {
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+    if (size_ && debug_check_)
+      debug_check_();
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+    return data_;
+  }
+
+  /// Get the size of the memory range.
+  std::size_t size() const BOOST_ASIO_NOEXCEPT
+  {
+    return size_;
+  }
+
+  /// Move the start of the buffer by the specified number of bytes.
+  mutable_buffer& operator+=(std::size_t n) BOOST_ASIO_NOEXCEPT
+  {
+    std::size_t offset = n < size_ ? n : size_;
+    data_ = static_cast<char*>(data_) + offset;
+    size_ -= offset;
+    return *this;
+  }
 
+private:
   void* data_;
   std::size_t size_;
 
@@ -135,26 +154,10 @@ class mutable_buffer
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
 };
 
-namespace detail {
-
-inline void* buffer_cast_helper(const mutable_buffer& b)
-{
-#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-  if (b.size_ && b.debug_check_)
-    b.debug_check_();
-#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-  return b.data_;
-}
-
-inline std::size_t buffer_size_helper(const mutable_buffer& b)
-{
-  return b.size_;
-}
-
-} // namespace detail
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 
-/// Adapts a single modifiable buffer so that it meets the requirements of the
-/// MutableBufferSequence concept.
+/// (Deprecated: Use mutable_buffer.) Adapts a single modifiable buffer so that
+/// it meets the requirements of the MutableBufferSequence concept.
 class mutable_buffers_1
   : public mutable_buffer
 {
@@ -166,30 +169,40 @@ class mutable_buffers_1
   typedef const mutable_buffer* const_iterator;
 
   /// Construct to represent a given memory range.
-  mutable_buffers_1(void* data, std::size_t size)
+  mutable_buffers_1(void* data, std::size_t size) BOOST_ASIO_NOEXCEPT
     : mutable_buffer(data, size)
   {
   }
 
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+  mutable_buffers_1(void* data, std::size_t size,
+      boost::asio::detail::function<void()> debug_check)
+    : mutable_buffer(data, size, debug_check)
+  {
+  }
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+
   /// Construct to represent a single modifiable buffer.
-  explicit mutable_buffers_1(const mutable_buffer& b)
+  explicit mutable_buffers_1(const mutable_buffer& b) BOOST_ASIO_NOEXCEPT
     : mutable_buffer(b)
   {
   }
 
   /// Get a random-access iterator to the first element.
-  const_iterator begin() const
+  const_iterator begin() const BOOST_ASIO_NOEXCEPT
   {
     return this;
   }
 
   /// Get a random-access iterator for one past the last element.
-  const_iterator end() const
+  const_iterator end() const BOOST_ASIO_NOEXCEPT
   {
     return begin() + 1;
   }
 };
 
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
 /// Holds a buffer that cannot be modified.
 /**
  * The const_buffer class provides a safe representation of a buffer that cannot
@@ -198,38 +211,38 @@ class mutable_buffers_1
  *
  * @par Accessing Buffer Contents
  *
- * The contents of a buffer may be accessed using the @ref buffer_size
- * and @ref buffer_cast functions:
+ * The contents of a buffer may be accessed using the @c data() and @c size()
+ * member functions:
  *
  * @code boost::asio::const_buffer b1 = ...;
- * std::size_t s1 = boost::asio::buffer_size(b1);
- * const unsigned char* p1 = boost::asio::buffer_cast<const unsigned char*>(b1);
+ * std::size_t s1 = b1.size();
+ * const unsigned char* p1 = static_cast<const unsigned char*>(b1.data());
  * @endcode
  *
- * The boost::asio::buffer_cast function permits violations of type safety, so
- * uses of it in application code should be carefully considered.
+ * The @c data() member function permits violations of type safety, so uses of
+ * it in application code should be carefully considered.
  */
 class const_buffer
 {
 public:
   /// Construct an empty buffer.
-  const_buffer()
+  const_buffer() BOOST_ASIO_NOEXCEPT
     : data_(0),
       size_(0)
   {
   }
 
   /// Construct a buffer to represent a given memory range.
-  const_buffer(const void* data, std::size_t size)
+  const_buffer(const void* data, std::size_t size) BOOST_ASIO_NOEXCEPT
     : data_(data),
       size_(size)
   {
   }
 
   /// Construct a non-modifiable buffer from a modifiable one.
-  const_buffer(const mutable_buffer& b)
-    : data_(boost::asio::detail::buffer_cast_helper(b)),
-      size_(boost::asio::detail::buffer_size_helper(b))
+  const_buffer(const mutable_buffer& b) BOOST_ASIO_NOEXCEPT
+    : data_(b.data()),
+      size_(b.size())
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
       , debug_check_(b.get_debug_check())
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
@@ -251,12 +264,32 @@ class const_buffer
   }
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
 
-private:
-  friend const void* boost::asio::detail::buffer_cast_helper(
-      const const_buffer& b);
-  friend std::size_t boost::asio::detail::buffer_size_helper(
-      const const_buffer& b);
+  /// Get a pointer to the beginning of the memory range.
+  const void* data() const BOOST_ASIO_NOEXCEPT
+  {
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+    if (size_ && debug_check_)
+      debug_check_();
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+    return data_;
+  }
+
+  /// Get the size of the memory range.
+  std::size_t size() const BOOST_ASIO_NOEXCEPT
+  {
+    return size_;
+  }
+
+  /// Move the start of the buffer by the specified number of bytes.
+  const_buffer& operator+=(std::size_t n) BOOST_ASIO_NOEXCEPT
+  {
+    std::size_t offset = n < size_ ? n : size_;
+    data_ = static_cast<const char*>(data_) + offset;
+    size_ -= offset;
+    return *this;
+  }
 
+private:
   const void* data_;
   std::size_t size_;
 
@@ -265,26 +298,10 @@ class const_buffer
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
 };
 
-namespace detail {
-
-inline const void* buffer_cast_helper(const const_buffer& b)
-{
-#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-  if (b.size_ && b.debug_check_)
-    b.debug_check_();
-#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-  return b.data_;
-}
-
-inline std::size_t buffer_size_helper(const const_buffer& b)
-{
-  return b.size_;
-}
-
-} // namespace detail
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 
-/// Adapts a single non-modifiable buffer so that it meets the requirements of
-/// the ConstBufferSequence concept.
+/// (Deprecated: Use const_buffer.) Adapts a single non-modifiable buffer so
+/// that it meets the requirements of the ConstBufferSequence concept.
 class const_buffers_1
   : public const_buffer
 {
@@ -296,32 +313,78 @@ class const_buffers_1
   typedef const const_buffer* const_iterator;
 
   /// Construct to represent a given memory range.
-  const_buffers_1(const void* data, std::size_t size)
+  const_buffers_1(const void* data, std::size_t size) BOOST_ASIO_NOEXCEPT
     : const_buffer(data, size)
   {
   }
 
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+  const_buffers_1(const void* data, std::size_t size,
+      boost::asio::detail::function<void()> debug_check)
+    : const_buffer(data, size, debug_check)
+  {
+  }
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+
   /// Construct to represent a single non-modifiable buffer.
-  explicit const_buffers_1(const const_buffer& b)
+  explicit const_buffers_1(const const_buffer& b) BOOST_ASIO_NOEXCEPT
     : const_buffer(b)
   {
   }
 
   /// Get a random-access iterator to the first element.
-  const_iterator begin() const
+  const_iterator begin() const BOOST_ASIO_NOEXCEPT
   {
     return this;
   }
 
   /// Get a random-access iterator for one past the last element.
-  const_iterator end() const
+  const_iterator end() const BOOST_ASIO_NOEXCEPT
   {
     return begin() + 1;
   }
 };
 
-/// An implementation of both the ConstBufferSequence and MutableBufferSequence
-/// concepts to represent a null buffer sequence.
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+/// Trait to determine whether a type satisfies the MutableBufferSequence
+/// requirements.
+template <typename T>
+struct is_mutable_buffer_sequence
+#if defined(GENERATING_DOCUMENTATION)
+  : integral_constant<bool, automatically_determined>
+#else // defined(GENERATING_DOCUMENTATION)
+  : boost::asio::detail::is_buffer_sequence<T, mutable_buffer>
+#endif // defined(GENERATING_DOCUMENTATION)
+{
+};
+
+/// Trait to determine whether a type satisfies the ConstBufferSequence
+/// requirements.
+template <typename T>
+struct is_const_buffer_sequence
+#if defined(GENERATING_DOCUMENTATION)
+  : integral_constant<bool, automatically_determined>
+#else // defined(GENERATING_DOCUMENTATION)
+  : boost::asio::detail::is_buffer_sequence<T, const_buffer>
+#endif // defined(GENERATING_DOCUMENTATION)
+{
+};
+
+/// Trait to determine whether a type satisfies the DynamicBuffer requirements.
+template <typename T>
+struct is_dynamic_buffer
+#if defined(GENERATING_DOCUMENTATION)
+  : integral_constant<bool, automatically_determined>
+#else // defined(GENERATING_DOCUMENTATION)
+  : boost::asio::detail::is_dynamic_buffer<T>
+#endif // defined(GENERATING_DOCUMENTATION)
+{
+};
+
+/// (Deprecated: Use the socket/descriptor wait() and async_wait() member
+/// functions.) An implementation of both the ConstBufferSequence and
+/// MutableBufferSequence concepts to represent a null buffer sequence.
 class null_buffers
 {
 public:
@@ -332,13 +395,13 @@ class null_buffers
   typedef const mutable_buffer* const_iterator;
 
   /// Get a random-access iterator to the first element.
-  const_iterator begin() const
+  const_iterator begin() const BOOST_ASIO_NOEXCEPT
   {
     return &buf_;
   }
 
   /// Get a random-access iterator for one past the last element.
-  const_iterator end() const
+  const_iterator end() const BOOST_ASIO_NOEXCEPT
   {
     return &buf_;
   }
@@ -347,61 +410,189 @@ class null_buffers
   mutable_buffer buf_;
 };
 
-/** @defgroup buffer_size boost::asio::buffer_size
+/** @defgroup buffer_sequence_begin boost::asio::buffer_sequence_begin
  *
- * @brief The boost::asio::buffer_size function determines the total number of
- * bytes in a buffer or buffer sequence.
+ * @brief The boost::asio::buffer_sequence_begin function returns an iterator
+ * pointing to the first element in a buffer sequence.
  */
 /*@{*/
 
-/// Get the number of bytes in a modifiable buffer.
-inline std::size_t buffer_size(const mutable_buffer& b)
+/// Get an iterator to the first element in a buffer sequence.
+inline const mutable_buffer* buffer_sequence_begin(const mutable_buffer& b)
 {
-  return detail::buffer_size_helper(b);
+  return &b;
 }
 
-/// Get the number of bytes in a modifiable buffer.
-inline std::size_t buffer_size(const mutable_buffers_1& b)
+/// Get an iterator to the first element in a buffer sequence.
+inline const const_buffer* buffer_sequence_begin(const const_buffer& b)
 {
-  return detail::buffer_size_helper(b);
+  return &b;
 }
 
-/// Get the number of bytes in a non-modifiable buffer.
-inline std::size_t buffer_size(const const_buffer& b)
+#if defined(BOOST_ASIO_HAS_DECLTYPE) || defined(GENERATING_DOCUMENTATION)
+
+/// Get an iterator to the first element in a buffer sequence.
+template <typename C>
+inline auto buffer_sequence_begin(C& c) -> decltype(c.begin())
 {
-  return detail::buffer_size_helper(b);
+  return c.begin();
 }
 
-/// Get the number of bytes in a non-modifiable buffer.
-inline std::size_t buffer_size(const const_buffers_1& b)
+/// Get an iterator to the first element in a buffer sequence.
+template <typename C>
+inline auto buffer_sequence_begin(const C& c) -> decltype(c.begin())
 {
-  return detail::buffer_size_helper(b);
+  return c.begin();
 }
 
-/// Get the total number of bytes in a buffer sequence.
-/** 
- * The @c BufferSequence template parameter may meet either of the @c
- * ConstBufferSequence or @c MutableBufferSequence type requirements.
+#else // defined(BOOST_ASIO_HAS_DECLTYPE) || defined(GENERATING_DOCUMENTATION)
+
+template <typename C>
+inline typename C::iterator buffer_sequence_begin(C& c)
+{
+  return c.begin();
+}
+
+template <typename C>
+inline typename C::const_iterator buffer_sequence_begin(const C& c)
+{
+  return c.begin();
+}
+
+#endif // defined(BOOST_ASIO_HAS_DECLTYPE) || defined(GENERATING_DOCUMENTATION)
+
+/*@}*/
+
+/** @defgroup buffer_sequence_end boost::asio::buffer_sequence_end
+ *
+ * @brief The boost::asio::buffer_sequence_end function returns an iterator
+ * pointing to one past the end element in a buffer sequence.
  */
+/*@{*/
+
+/// Get an iterator to one past the end element in a buffer sequence.
+inline const mutable_buffer* buffer_sequence_end(const mutable_buffer& b)
+{
+  return &b + 1;
+}
+
+/// Get an iterator to one past the end element in a buffer sequence.
+inline const const_buffer* buffer_sequence_end(const const_buffer& b)
+{
+  return &b + 1;
+}
+
+#if defined(BOOST_ASIO_HAS_DECLTYPE) || defined(GENERATING_DOCUMENTATION)
+
+/// Get an iterator to one past the end element in a buffer sequence.
+template <typename C>
+inline auto buffer_sequence_end(C& c) -> decltype(c.end())
+{
+  return c.end();
+}
+
+/// Get an iterator to one past the end element in a buffer sequence.
+template <typename C>
+inline auto buffer_sequence_end(const C& c) -> decltype(c.end())
+{
+  return c.end();
+}
+
+#else // defined(BOOST_ASIO_HAS_DECLTYPE) || defined(GENERATING_DOCUMENTATION)
+
+template <typename C>
+inline typename C::iterator buffer_sequence_end(C& c)
+{
+  return c.end();
+}
+
+template <typename C>
+inline typename C::const_iterator buffer_sequence_end(const C& c)
+{
+  return c.end();
+}
+
+#endif // defined(BOOST_ASIO_HAS_DECLTYPE) || defined(GENERATING_DOCUMENTATION)
+
+/*@}*/
+
+namespace detail {
+
+// Tag types used to select appropriately optimised overloads.
+struct one_buffer {};
+struct multiple_buffers {};
+
+// Helper trait to detect single buffers.
 template <typename BufferSequence>
-inline std::size_t buffer_size(const BufferSequence& b)
+struct buffer_sequence_cardinality :
+  conditional<
+    is_same<BufferSequence, mutable_buffer>::value
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+      || is_same<BufferSequence, mutable_buffers_1>::value
+      || is_same<BufferSequence, const_buffers_1>::value
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+      || is_same<BufferSequence, const_buffer>::value,
+    one_buffer, multiple_buffers>::type {};
+
+template <typename Iterator>
+inline std::size_t buffer_size(one_buffer,
+    Iterator begin, Iterator) BOOST_ASIO_NOEXCEPT
+{
+  return const_buffer(*begin).size();
+}
+
+template <typename Iterator>
+inline std::size_t buffer_size(multiple_buffers,
+    Iterator begin, Iterator end) BOOST_ASIO_NOEXCEPT
 {
   std::size_t total_buffer_size = 0;
 
-  typename BufferSequence::const_iterator iter = b.begin();
-  typename BufferSequence::const_iterator end = b.end();
+  Iterator iter = begin;
   for (; iter != end; ++iter)
-    total_buffer_size += detail::buffer_size_helper(*iter);
+  {
+    const_buffer b(*iter);
+    total_buffer_size += b.size();
+  }
 
   return total_buffer_size;
 }
 
-/*@}*/
+} // namespace detail
+
+/// Get the total number of bytes in a buffer sequence.
+/**
+ * The @c buffer_size function determines the total size of all buffers in the
+ * buffer sequence, as if computed as follows:
+ *
+ * @code size_t total_size = 0;
+ * auto i = boost::asio::buffer_sequence_begin(buffers);
+ * auto end = boost::asio::buffer_sequence_end(buffers);
+ * for (; i != end; ++i)
+ * {
+ *   const_buffer b(*i);
+ *   total_size += b.size();
+ * }
+ * return total_size; @endcode
+ *
+ * The @c BufferSequence template parameter may meet either of the @c
+ * ConstBufferSequence or @c MutableBufferSequence type requirements.
+ */
+template <typename BufferSequence>
+inline std::size_t buffer_size(const BufferSequence& b) BOOST_ASIO_NOEXCEPT
+{
+  return detail::buffer_size(
+      detail::buffer_sequence_cardinality<BufferSequence>(),
+      boost::asio::buffer_sequence_begin(b),
+      boost::asio::buffer_sequence_end(b));
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 
 /** @defgroup buffer_cast boost::asio::buffer_cast
  *
- * @brief The boost::asio::buffer_cast function is used to obtain a pointer to
- * the underlying memory region associated with a buffer.
+ * @brief (Deprecated: Use the @c data() member function.) The
+ * boost::asio::buffer_cast function is used to obtain a pointer to the
+ * underlying memory region associated with a buffer.
  *
  * @par Examples:
  *
@@ -422,30 +613,32 @@ inline std::size_t buffer_size(const BufferSequence& b)
 
 /// Cast a non-modifiable buffer to a specified pointer to POD type.
 template <typename PointerToPodType>
-inline PointerToPodType buffer_cast(const mutable_buffer& b)
+inline PointerToPodType buffer_cast(const mutable_buffer& b) BOOST_ASIO_NOEXCEPT
 {
-  return static_cast<PointerToPodType>(detail::buffer_cast_helper(b));
+  return static_cast<PointerToPodType>(b.data());
 }
 
 /// Cast a non-modifiable buffer to a specified pointer to POD type.
 template <typename PointerToPodType>
-inline PointerToPodType buffer_cast(const const_buffer& b)
+inline PointerToPodType buffer_cast(const const_buffer& b) BOOST_ASIO_NOEXCEPT
 {
-  return static_cast<PointerToPodType>(detail::buffer_cast_helper(b));
+  return static_cast<PointerToPodType>(b.data());
 }
 
 /*@}*/
 
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
 /// Create a new modifiable buffer that is offset from the start of another.
 /**
  * @relates mutable_buffer
  */
-inline mutable_buffer operator+(const mutable_buffer& b, std::size_t start)
+inline mutable_buffer operator+(const mutable_buffer& b,
+    std::size_t n) BOOST_ASIO_NOEXCEPT
 {
-  if (start > buffer_size(b))
-    return mutable_buffer();
-  char* new_data = buffer_cast<char*>(b) + start;
-  std::size_t new_size = buffer_size(b) - start;
+  std::size_t offset = n < b.size() ? n : b.size();
+  char* new_data = static_cast<char*>(b.data()) + offset;
+  std::size_t new_size = b.size() - offset;
   return mutable_buffer(new_data, new_size
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
       , b.get_debug_check()
@@ -457,29 +650,22 @@ inline mutable_buffer operator+(const mutable_buffer& b, std::size_t start)
 /**
  * @relates mutable_buffer
  */
-inline mutable_buffer operator+(std::size_t start, const mutable_buffer& b)
+inline mutable_buffer operator+(std::size_t n,
+    const mutable_buffer& b) BOOST_ASIO_NOEXCEPT
 {
-  if (start > buffer_size(b))
-    return mutable_buffer();
-  char* new_data = buffer_cast<char*>(b) + start;
-  std::size_t new_size = buffer_size(b) - start;
-  return mutable_buffer(new_data, new_size
-#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-      , b.get_debug_check()
-#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-      );
+  return b + n;
 }
 
 /// Create a new non-modifiable buffer that is offset from the start of another.
 /**
  * @relates const_buffer
  */
-inline const_buffer operator+(const const_buffer& b, std::size_t start)
+inline const_buffer operator+(const const_buffer& b,
+    std::size_t n) BOOST_ASIO_NOEXCEPT
 {
-  if (start > buffer_size(b))
-    return const_buffer();
-  const char* new_data = buffer_cast<const char*>(b) + start;
-  std::size_t new_size = buffer_size(b) - start;
+  std::size_t offset = n < b.size() ? n : b.size();
+  const char* new_data = static_cast<const char*>(b.data()) + offset;
+  std::size_t new_size = b.size() - offset;
   return const_buffer(new_data, new_size
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
       , b.get_debug_check()
@@ -491,17 +677,10 @@ inline const_buffer operator+(const const_buffer& b, std::size_t start)
 /**
  * @relates const_buffer
  */
-inline const_buffer operator+(std::size_t start, const const_buffer& b)
+inline const_buffer operator+(std::size_t n,
+    const const_buffer& b) BOOST_ASIO_NOEXCEPT
 {
-  if (start > buffer_size(b))
-    return const_buffer();
-  const char* new_data = buffer_cast<const char*>(b) + start;
-  std::size_t new_size = buffer_size(b) - start;
-  return const_buffer(new_data, new_size
-#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-      , b.get_debug_check()
-#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-      );
+  return b + n;
 }
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
@@ -586,32 +765,33 @@ class buffer_debug_check
  *
  * @par Accessing Buffer Contents
  *
- * The contents of a buffer may be accessed using the @ref buffer_size and
- * @ref buffer_cast functions:
+ * The contents of a buffer may be accessed using the @c data() and @c size()
+ * member functions:
  *
  * @code boost::asio::mutable_buffer b1 = ...;
- * std::size_t s1 = boost::asio::buffer_size(b1);
- * unsigned char* p1 = boost::asio::buffer_cast<unsigned char*>(b1);
+ * std::size_t s1 = b1.size();
+ * unsigned char* p1 = static_cast<unsigned char*>(b1.data());
  *
  * boost::asio::const_buffer b2 = ...;
- * std::size_t s2 = boost::asio::buffer_size(b2);
- * const void* p2 = boost::asio::buffer_cast<const void*>(b2); @endcode
+ * std::size_t s2 = b2.size();
+ * const void* p2 = b2.data(); @endcode
  *
- * The boost::asio::buffer_cast function permits violations of type safety, so
+ * The @c data() member function permits violations of type safety, so
  * uses of it in application code should be carefully considered.
  *
- * For convenience, the @ref buffer_size function also works on buffer
- * sequences (that is, types meeting the ConstBufferSequence or
- * MutableBufferSequence type requirements). In this case, the function returns
- * the total size of all buffers in the sequence.
+ * For convenience, a @ref buffer_size function is provided that works with
+ * both buffers and buffer sequences (that is, types meeting the
+ * ConstBufferSequence or MutableBufferSequence type requirements). In this
+ * case, the function returns the total size of all buffers in the sequence.
  *
  * @par Buffer Copying
  *
  * The @ref buffer_copy function may be used to copy raw bytes between
  * individual buffers and buffer sequences.
- *
- * In particular, when used with the @ref buffer_size, the @ref buffer_copy
- * function can be used to linearise a sequence of buffers. For example:
+*
+ * In particular, when used with the @ref buffer_size function, the @ref
+ * buffer_copy function can be used to linearise a sequence of buffers. For
+ * example:
  *
  * @code vector<const_buffer> buffers = ...;
  *
@@ -700,29 +880,38 @@ class buffer_debug_check
  */
 /*@{*/
 
+#if defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+# define BOOST_ASIO_MUTABLE_BUFFER mutable_buffer
+# define BOOST_ASIO_CONST_BUFFER const_buffer
+#else // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+# define BOOST_ASIO_MUTABLE_BUFFER mutable_buffers_1
+# define BOOST_ASIO_CONST_BUFFER const_buffers_1
+#endif // defined(BOOST_ASIO_NO_DEPRECATED) || defined(GENERATING_DOCUMENTATION)
+
 /// Create a new modifiable buffer from an existing buffer.
 /**
- * @returns <tt>mutable_buffers_1(b)</tt>.
+ * @returns <tt>mutable_buffer(b)</tt>.
  */
-inline mutable_buffers_1 buffer(const mutable_buffer& b)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(
+    const mutable_buffer& b) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(b);
+  return BOOST_ASIO_MUTABLE_BUFFER(b);
 }
 
 /// Create a new modifiable buffer from an existing buffer.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
- *     buffer_cast<void*>(b),
- *     min(buffer_size(b), max_size_in_bytes)); @endcode
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
+ *     b.data(),
+ *     min(b.size(), max_size_in_bytes)); @endcode
  */
-inline mutable_buffers_1 buffer(const mutable_buffer& b,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(const mutable_buffer& b,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(buffer_cast<void*>(b),
-        buffer_size(b) < max_size_in_bytes
-        ? buffer_size(b) : max_size_in_bytes
+  return BOOST_ASIO_MUTABLE_BUFFER(
+      mutable_buffer(b.data(),
+        b.size() < max_size_in_bytes
+        ? b.size() : max_size_in_bytes
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
         , b.get_debug_check()
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
@@ -731,110 +920,110 @@ inline mutable_buffers_1 buffer(const mutable_buffer& b,
 
 /// Create a new non-modifiable buffer from an existing buffer.
 /**
- * @returns <tt>const_buffers_1(b)</tt>.
+ * @returns <tt>const_buffer(b)</tt>.
  */
-inline const_buffers_1 buffer(const const_buffer& b)
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const const_buffer& b) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(b);
+  return BOOST_ASIO_CONST_BUFFER(b);
 }
 
 /// Create a new non-modifiable buffer from an existing buffer.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
- *     buffer_cast<const void*>(b),
- *     min(buffer_size(b), max_size_in_bytes)); @endcode
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
+ *     b.data(),
+ *     min(b.size(), max_size_in_bytes)); @endcode
  */
-inline const_buffers_1 buffer(const const_buffer& b,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(const const_buffer& b,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(buffer_cast<const void*>(b),
-        buffer_size(b) < max_size_in_bytes
-        ? buffer_size(b) : max_size_in_bytes
+  return BOOST_ASIO_CONST_BUFFER(b.data(),
+      b.size() < max_size_in_bytes
+      ? b.size() : max_size_in_bytes
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-        , b.get_debug_check()
+      , b.get_debug_check()
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-        ));
+      );
 }
 
 /// Create a new modifiable buffer that represents the given memory range.
 /**
- * @returns <tt>mutable_buffers_1(data, size_in_bytes)</tt>.
+ * @returns <tt>mutable_buffer(data, size_in_bytes)</tt>.
  */
-inline mutable_buffers_1 buffer(void* data, std::size_t size_in_bytes)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(void* data,
+    std::size_t size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(mutable_buffer(data, size_in_bytes));
+  return BOOST_ASIO_MUTABLE_BUFFER(data, size_in_bytes);
 }
 
 /// Create a new non-modifiable buffer that represents the given memory range.
 /**
- * @returns <tt>const_buffers_1(data, size_in_bytes)</tt>.
+ * @returns <tt>const_buffer(data, size_in_bytes)</tt>.
  */
-inline const_buffers_1 buffer(const void* data,
-    std::size_t size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(const void* data,
+    std::size_t size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(const_buffer(data, size_in_bytes));
+  return BOOST_ASIO_CONST_BUFFER(data, size_in_bytes);
 }
 
 /// Create a new modifiable buffer that represents the given POD array.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     static_cast<void*>(data),
  *     N * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline mutable_buffers_1 buffer(PodType (&data)[N])
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(PodType (&data)[N]) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(mutable_buffer(data, N * sizeof(PodType)));
+  return BOOST_ASIO_MUTABLE_BUFFER(data, N * sizeof(PodType));
 }
  
 /// Create a new modifiable buffer that represents the given POD array.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     static_cast<void*>(data),
  *     min(N * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline mutable_buffers_1 buffer(PodType (&data)[N],
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(PodType (&data)[N],
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(data,
-        N * sizeof(PodType) < max_size_in_bytes
-        ? N * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_MUTABLE_BUFFER(data,
+      N * sizeof(PodType) < max_size_in_bytes
+      ? N * sizeof(PodType) : max_size_in_bytes);
 }
  
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     static_cast<const void*>(data),
  *     N * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(const PodType (&data)[N])
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const PodType (&data)[N]) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(const_buffer(data, N * sizeof(PodType)));
+  return BOOST_ASIO_CONST_BUFFER(data, N * sizeof(PodType));
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     static_cast<const void*>(data),
  *     min(N * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(const PodType (&data)[N],
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(const PodType (&data)[N],
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data,
-        N * sizeof(PodType) < max_size_in_bytes
-        ? N * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_CONST_BUFFER(data,
+      N * sizeof(PodType) < max_size_in_bytes
+      ? N * sizeof(PodType) : max_size_in_bytes);
 }
 
 #if defined(BOOST_ASIO_ENABLE_ARRAY_BUFFER_WORKAROUND)
@@ -860,14 +1049,14 @@ template <>
 struct buffer_types_base<false>
 {
   typedef mutable_buffer buffer_type;
-  typedef mutable_buffers_1 container_type;
+  typedef BOOST_ASIO_MUTABLE_BUFFER container_type;
 };
 
 template <>
 struct buffer_types_base<true>
 {
   typedef const_buffer buffer_type;
-  typedef const_buffers_1 container_type;
+  typedef BOOST_ASIO_CONST_BUFFER container_type;
 };
 
 template <typename PodType>
@@ -880,7 +1069,7 @@ struct buffer_types
 
 template <typename PodType, std::size_t N>
 inline typename detail::buffer_types<PodType>::container_type
-buffer(boost::array<PodType, N>& data)
+buffer(boost::array<PodType, N>& data) BOOST_ASIO_NOEXCEPT
 {
   typedef typename boost::asio::detail::buffer_types<PodType>::buffer_type
     buffer_type;
@@ -892,7 +1081,8 @@ buffer(boost::array<PodType, N>& data)
 
 template <typename PodType, std::size_t N>
 inline typename detail::buffer_types<PodType>::container_type
-buffer(boost::array<PodType, N>& data, std::size_t max_size_in_bytes)
+buffer(boost::array<PodType, N>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
   typedef typename boost::asio::detail::buffer_types<PodType>::buffer_type
     buffer_type;
@@ -908,200 +1098,195 @@ buffer(boost::array<PodType, N>& data, std::size_t max_size_in_bytes)
 
 /// Create a new modifiable buffer that represents the given POD array.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     data.data(),
  *     data.size() * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline mutable_buffers_1 buffer(boost::array<PodType, N>& data)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(
+    boost::array<PodType, N>& data) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(data.c_array(), data.size() * sizeof(PodType)));
+  return BOOST_ASIO_MUTABLE_BUFFER(
+      data.c_array(), data.size() * sizeof(PodType));
 }
 
 /// Create a new modifiable buffer that represents the given POD array.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     data.data(),
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline mutable_buffers_1 buffer(boost::array<PodType, N>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(boost::array<PodType, N>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(data.c_array(),
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_MUTABLE_BUFFER(data.c_array(),
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes);
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     data.size() * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(boost::array<const PodType, N>& data)
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    boost::array<const PodType, N>& data) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(), data.size() * sizeof(PodType)));
+  return BOOST_ASIO_CONST_BUFFER(data.data(), data.size() * sizeof(PodType));
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(boost::array<const PodType, N>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(boost::array<const PodType, N>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(),
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_CONST_BUFFER(data.data(),
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes);
 }
 
 #endif // defined(BOOST_ASIO_ENABLE_ARRAY_BUFFER_WORKAROUND)
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     data.size() * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(const boost::array<PodType, N>& data)
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const boost::array<PodType, N>& data) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(), data.size() * sizeof(PodType)));
+  return BOOST_ASIO_CONST_BUFFER(data.data(), data.size() * sizeof(PodType));
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(const boost::array<PodType, N>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(const boost::array<PodType, N>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(),
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_CONST_BUFFER(data.data(),
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes);
 }
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY) || defined(GENERATING_DOCUMENTATION)
 
 /// Create a new modifiable buffer that represents the given POD array.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     data.data(),
  *     data.size() * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline mutable_buffers_1 buffer(std::array<PodType, N>& data)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(
+    std::array<PodType, N>& data) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(data.data(), data.size() * sizeof(PodType)));
+  return BOOST_ASIO_MUTABLE_BUFFER(data.data(), data.size() * sizeof(PodType));
 }
 
 /// Create a new modifiable buffer that represents the given POD array.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     data.data(),
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline mutable_buffers_1 buffer(std::array<PodType, N>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(std::array<PodType, N>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(data.data(),
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_MUTABLE_BUFFER(data.data(),
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes);
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     data.size() * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(std::array<const PodType, N>& data)
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    std::array<const PodType, N>& data) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(), data.size() * sizeof(PodType)));
+  return BOOST_ASIO_CONST_BUFFER(data.data(), data.size() * sizeof(PodType));
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(std::array<const PodType, N>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(std::array<const PodType, N>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(),
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_CONST_BUFFER(data.data(),
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes);
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     data.size() * sizeof(PodType)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(const std::array<PodType, N>& data)
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const std::array<PodType, N>& data) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(), data.size() * sizeof(PodType)));
+  return BOOST_ASIO_CONST_BUFFER(data.data(), data.size() * sizeof(PodType));
 }
 
 /// Create a new non-modifiable buffer that represents the given POD array.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.data(),
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  */
 template <typename PodType, std::size_t N>
-inline const_buffers_1 buffer(const std::array<PodType, N>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(const std::array<PodType, N>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(),
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes));
+  return BOOST_ASIO_CONST_BUFFER(data.data(),
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes);
 }
 
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY) || defined(GENERATING_DOCUMENTATION)
 
 /// Create a new modifiable buffer that represents the given POD vector.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     data.size() ? &data[0] : 0,
  *     data.size() * sizeof(PodType)); @endcode
  *
@@ -1109,22 +1294,23 @@ inline const_buffers_1 buffer(const std::array<PodType, N>& data,
  * invalidate iterators.
  */
 template <typename PodType, typename Allocator>
-inline mutable_buffers_1 buffer(std::vector<PodType, Allocator>& data)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(
+    std::vector<PodType, Allocator>& data) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(data.size() ? &data[0] : 0, data.size() * sizeof(PodType)
+  return BOOST_ASIO_MUTABLE_BUFFER(
+      data.size() ? &data[0] : 0, data.size() * sizeof(PodType)
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-        , detail::buffer_debug_check<
-            typename std::vector<PodType, Allocator>::iterator
-          >(data.begin())
+      , detail::buffer_debug_check<
+          typename std::vector<PodType, Allocator>::iterator
+        >(data.begin())
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-        ));
+      );
 }
 
 /// Create a new modifiable buffer that represents the given POD vector.
 /**
- * @returns A mutable_buffers_1 value equivalent to:
- * @code mutable_buffers_1(
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
  *     data.size() ? &data[0] : 0,
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  *
@@ -1132,25 +1318,24 @@ inline mutable_buffers_1 buffer(std::vector<PodType, Allocator>& data)
  * invalidate iterators.
  */
 template <typename PodType, typename Allocator>
-inline mutable_buffers_1 buffer(std::vector<PodType, Allocator>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(std::vector<PodType, Allocator>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return mutable_buffers_1(
-      mutable_buffer(data.size() ? &data[0] : 0,
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes
+  return BOOST_ASIO_MUTABLE_BUFFER(data.size() ? &data[0] : 0,
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-        , detail::buffer_debug_check<
-            typename std::vector<PodType, Allocator>::iterator
-          >(data.begin())
+      , detail::buffer_debug_check<
+          typename std::vector<PodType, Allocator>::iterator
+        >(data.begin())
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-        ));
+      );
 }
 
 /// Create a new non-modifiable buffer that represents the given POD vector.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.size() ? &data[0] : 0,
  *     data.size() * sizeof(PodType)); @endcode
  *
@@ -1158,23 +1343,23 @@ inline mutable_buffers_1 buffer(std::vector<PodType, Allocator>& data,
  * invalidate iterators.
  */
 template <typename PodType, typename Allocator>
-inline const_buffers_1 buffer(
-    const std::vector<PodType, Allocator>& data)
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const std::vector<PodType, Allocator>& data) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.size() ? &data[0] : 0, data.size() * sizeof(PodType)
+  return BOOST_ASIO_CONST_BUFFER(
+      data.size() ? &data[0] : 0, data.size() * sizeof(PodType)
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-        , detail::buffer_debug_check<
-            typename std::vector<PodType, Allocator>::const_iterator
-          >(data.begin())
+      , detail::buffer_debug_check<
+          typename std::vector<PodType, Allocator>::const_iterator
+        >(data.begin())
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-        ));
+      );
 }
 
 /// Create a new non-modifiable buffer that represents the given POD vector.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
  *     data.size() ? &data[0] : 0,
  *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
  *
@@ -1182,963 +1367,729 @@ inline const_buffers_1 buffer(
  * invalidate iterators.
  */
 template <typename PodType, typename Allocator>
-inline const_buffers_1 buffer(
-    const std::vector<PodType, Allocator>& data, std::size_t max_size_in_bytes)
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const std::vector<PodType, Allocator>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.size() ? &data[0] : 0,
-        data.size() * sizeof(PodType) < max_size_in_bytes
-        ? data.size() * sizeof(PodType) : max_size_in_bytes
+  return BOOST_ASIO_CONST_BUFFER(data.size() ? &data[0] : 0,
+      data.size() * sizeof(PodType) < max_size_in_bytes
+      ? data.size() * sizeof(PodType) : max_size_in_bytes
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-        , detail::buffer_debug_check<
-            typename std::vector<PodType, Allocator>::const_iterator
-          >(data.begin())
+      , detail::buffer_debug_check<
+          typename std::vector<PodType, Allocator>::const_iterator
+        >(data.begin())
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-        ));
+      );
 }
 
-/// Create a new non-modifiable buffer that represents the given string.
+/// Create a new modifiable buffer that represents the given string.
 /**
- * @returns <tt>const_buffers_1(data.data(), data.size() * sizeof(Elem))</tt>.
+ * @returns <tt>mutable_buffer(data.size() ? &data[0] : 0,
+ * data.size() * sizeof(Elem))</tt>.
  *
  * @note The buffer is invalidated by any non-const operation called on the
  * given string object.
  */
 template <typename Elem, typename Traits, typename Allocator>
-inline const_buffers_1 buffer(
-    const std::basic_string<Elem, Traits, Allocator>& data)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(
+    std::basic_string<Elem, Traits, Allocator>& data) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(const_buffer(data.data(), data.size() * sizeof(Elem)
+  return BOOST_ASIO_MUTABLE_BUFFER(data.size() ? &data[0] : 0,
+      data.size() * sizeof(Elem)
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-        , detail::buffer_debug_check<
-            typename std::basic_string<Elem, Traits, Allocator>::const_iterator
-          >(data.begin())
+      , detail::buffer_debug_check<
+          typename std::basic_string<Elem, Traits, Allocator>::iterator
+        >(data.begin())
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-        ));
+      );
 }
 
 /// Create a new non-modifiable buffer that represents the given string.
 /**
- * @returns A const_buffers_1 value equivalent to:
- * @code const_buffers_1(
- *     data.data(),
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
+ *     data.size() ? &data[0] : 0,
  *     min(data.size() * sizeof(Elem), max_size_in_bytes)); @endcode
  *
  * @note The buffer is invalidated by any non-const operation called on the
  * given string object.
  */
 template <typename Elem, typename Traits, typename Allocator>
-inline const_buffers_1 buffer(
-    const std::basic_string<Elem, Traits, Allocator>& data,
-    std::size_t max_size_in_bytes)
+inline BOOST_ASIO_MUTABLE_BUFFER buffer(
+    std::basic_string<Elem, Traits, Allocator>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return const_buffers_1(
-      const_buffer(data.data(),
-        data.size() * sizeof(Elem) < max_size_in_bytes
-        ? data.size() * sizeof(Elem) : max_size_in_bytes
+  return BOOST_ASIO_MUTABLE_BUFFER(data.size() ? &data[0] : 0,
+      data.size() * sizeof(Elem) < max_size_in_bytes
+      ? data.size() * sizeof(Elem) : max_size_in_bytes
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
-        , detail::buffer_debug_check<
-            typename std::basic_string<Elem, Traits, Allocator>::const_iterator
-          >(data.begin())
+      , detail::buffer_debug_check<
+          typename std::basic_string<Elem, Traits, Allocator>::iterator
+        >(data.begin())
 #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
-        ));
+      );
 }
 
-/*@}*/
-
-/** @defgroup buffer_copy boost::asio::buffer_copy
- *
- * @brief The boost::asio::buffer_copy function is used to copy bytes from a
- * source buffer (or buffer sequence) to a target buffer (or buffer sequence).
- *
- * The @c buffer_copy function is available in two forms:
- *
- * @li A 2-argument form: @c buffer_copy(target, source)
- *
- * @li A 3-argument form: @c buffer_copy(target, source, max_bytes_to_copy)
-
- * Both forms return the number of bytes actually copied. The number of bytes
- * copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c If specified, @c max_bytes_to_copy.
- *
- * This prevents buffer overflow, regardless of the buffer sizes used in the
- * copy operation.
+/// Create a new non-modifiable buffer that represents the given string.
+/**
+ * @returns <tt>const_buffer(data.data(), data.size() * sizeof(Elem))</tt>.
  *
- * Note that @ref buffer_copy is implemented in terms of @c memcpy, and
- * consequently it cannot be used to copy between overlapping memory regions.
+ * @note The buffer is invalidated by any non-const operation called on the
+ * given string object.
  */
-/*@{*/
+template <typename Elem, typename Traits, typename Allocator>
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const std::basic_string<Elem, Traits, Allocator>& data) BOOST_ASIO_NOEXCEPT
+{
+  return BOOST_ASIO_CONST_BUFFER(data.data(), data.size() * sizeof(Elem)
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+      , detail::buffer_debug_check<
+          typename std::basic_string<Elem, Traits, Allocator>::const_iterator
+        >(data.begin())
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+      );
+}
 
-/// Copies bytes from a source buffer to a target buffer.
+/// Create a new non-modifiable buffer that represents the given string.
 /**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
+ * @returns A const_buffer value equivalent to:
+ * @code const_buffer(
+ *     data.data(),
+ *     min(data.size() * sizeof(Elem), max_size_in_bytes)); @endcode
  *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * @note The buffer is invalidated by any non-const operation called on the
+ * given string object.
  */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const const_buffer& source)
+template <typename Elem, typename Traits, typename Allocator>
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    const std::basic_string<Elem, Traits, Allocator>& data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  using namespace std; // For memcpy.
-  std::size_t target_size = buffer_size(target);
-  std::size_t source_size = buffer_size(source);
-  std::size_t n = target_size < source_size ? target_size : source_size;
-  memcpy(buffer_cast<void*>(target), buffer_cast<const void*>(source), n);
-  return n;
+  return BOOST_ASIO_CONST_BUFFER(data.data(),
+      data.size() * sizeof(Elem) < max_size_in_bytes
+      ? data.size() * sizeof(Elem) : max_size_in_bytes
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+      , detail::buffer_debug_check<
+          typename std::basic_string<Elem, Traits, Allocator>::const_iterator
+        >(data.begin())
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+      );
 }
 
-/// Copies bytes from a source buffer to a target buffer.
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Create a new modifiable buffer that represents the given string_view.
 /**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * @returns <tt>mutable_buffer(data.size() ? &data[0] : 0,
+ * data.size() * sizeof(Elem))</tt>.
  */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const const_buffers_1& source)
+template <typename Elem, typename Traits>
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    basic_string_view<Elem, Traits> data) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(target, static_cast<const const_buffer&>(source));
+  return BOOST_ASIO_CONST_BUFFER(data.size() ? &data[0] : 0,
+      data.size() * sizeof(Elem)
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+      , detail::buffer_debug_check<
+          typename basic_string_view<Elem, Traits>::iterator
+        >(data.begin())
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+      );
 }
 
-/// Copies bytes from a source buffer to a target buffer.
+/// Create a new non-modifiable buffer that represents the given string.
 /**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * @returns A mutable_buffer value equivalent to:
+ * @code mutable_buffer(
+ *     data.size() ? &data[0] : 0,
+ *     min(data.size() * sizeof(Elem), max_size_in_bytes)); @endcode
  */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const mutable_buffer& source)
+template <typename Elem, typename Traits>
+inline BOOST_ASIO_CONST_BUFFER buffer(
+    basic_string_view<Elem, Traits> data,
+    std::size_t max_size_in_bytes) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(target, const_buffer(source));
+  return BOOST_ASIO_CONST_BUFFER(data.size() ? &data[0] : 0,
+      data.size() * sizeof(Elem) < max_size_in_bytes
+      ? data.size() * sizeof(Elem) : max_size_in_bytes
+#if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
+      , detail::buffer_debug_check<
+          typename basic_string_view<Elem, Traits>::iterator
+        >(data.begin())
+#endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
+      );
 }
 
-/// Copies bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const mutable_buffers_1& source)
-{
-  return buffer_copy(target, const_buffer(source));
-}
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+       //  || defined(GENERATING_DOCUMENTATION)
+
+/*@}*/
 
-/// Copies bytes from a source buffer sequence to a target buffer.
+/// Adapt a basic_string to the DynamicBuffer requirements.
 /**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer sequence representing the memory
- * regions from which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * Requires that <tt>sizeof(Elem) == 1</tt>.
  */
-template <typename ConstBufferSequence>
-std::size_t buffer_copy(const mutable_buffer& target,
-    const ConstBufferSequence& source)
+template <typename Elem, typename Traits, typename Allocator>
+class dynamic_string_buffer
 {
-  std::size_t total_bytes_copied = 0;
-
-  typename ConstBufferSequence::const_iterator source_iter = source.begin();
-  typename ConstBufferSequence::const_iterator source_end = source.end();
-
-  for (mutable_buffer target_buffer(target);
-      buffer_size(target_buffer) && source_iter != source_end; ++source_iter)
+public:
+  /// The type used to represent the input sequence as a list of buffers.
+  typedef BOOST_ASIO_CONST_BUFFER const_buffers_type;
+
+  /// The type used to represent the output sequence as a list of buffers.
+  typedef BOOST_ASIO_MUTABLE_BUFFER mutable_buffers_type;
+
+  /// Construct a dynamic buffer from a string.
+  /**
+   * @param s The string to be used as backing storage for the dynamic buffer.
+   * Any existing data in the string is treated as the dynamic buffer's input
+   * sequence. The object stores a reference to the string and the user is
+   * responsible for ensuring that the string object remains valid until the
+   * dynamic_string_buffer object is destroyed.
+   *
+   * @param maximum_size Specifies a maximum size for the buffer, in bytes.
+   */
+  explicit dynamic_string_buffer(std::basic_string<Elem, Traits, Allocator>& s,
+      std::size_t maximum_size =
+        (std::numeric_limits<std::size_t>::max)()) BOOST_ASIO_NOEXCEPT
+    : string_(s),
+      size_(string_.size()),
+      max_size_(maximum_size)
   {
-    const_buffer source_buffer(*source_iter);
-    std::size_t bytes_copied = buffer_copy(target_buffer, source_buffer);
-    total_bytes_copied += bytes_copied;
-    target_buffer = target_buffer + bytes_copied;
   }
 
-  return total_bytes_copied;
-}
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move construct a dynamic buffer.
+  dynamic_string_buffer(dynamic_string_buffer&& other) BOOST_ASIO_NOEXCEPT
+    : string_(other.string_),
+      size_(other.size_),
+      max_size_(other.max_size_)
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
-/// Copies bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const const_buffer& source)
-{
-  return buffer_copy(static_cast<const mutable_buffer&>(target), source);
-}
+  /// Get the size of the input sequence.
+  std::size_t size() const BOOST_ASIO_NOEXCEPT
+  {
+    return size_;
+  }
 
-/// Copies bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const const_buffers_1& source)
-{
-  return buffer_copy(static_cast<const mutable_buffer&>(target),
-      static_cast<const const_buffer&>(source));
-}
+  /// Get the maximum size of the dynamic buffer.
+  /**
+   * @returns The allowed maximum of the sum of the sizes of the input sequence
+   * and output sequence.
+   */
+  std::size_t max_size() const BOOST_ASIO_NOEXCEPT
+  {
+    return max_size_;
+  }
 
-/// Copies bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const mutable_buffer& source)
-{
-  return buffer_copy(static_cast<const mutable_buffer&>(target),
-      const_buffer(source));
-}
+  /// Get the current capacity of the dynamic buffer.
+  /**
+   * @returns The current total capacity of the buffer, i.e. for both the input
+   * sequence and output sequence.
+   */
+  std::size_t capacity() const BOOST_ASIO_NOEXCEPT
+  {
+    return string_.capacity();
+  }
 
-/// Copies bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const mutable_buffers_1& source)
-{
-  return buffer_copy(static_cast<const mutable_buffer&>(target),
-      const_buffer(source));
-}
+  /// Get a list of buffers that represents the input sequence.
+  /**
+   * @returns An object of type @c const_buffers_type that satisfies
+   * ConstBufferSequence requirements, representing the basic_string memory in
+   * input sequence.
+   *
+   * @note The returned object is invalidated by any @c dynamic_string_buffer
+   * or @c basic_string member function that modifies the input sequence or
+   * output sequence.
+   */
+  const_buffers_type data() const BOOST_ASIO_NOEXCEPT
+  {
+    return const_buffers_type(boost::asio::buffer(string_, size_));
+  }
 
-/// Copies bytes from a source buffer sequence to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer sequence representing the memory
- * regions from which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-template <typename ConstBufferSequence>
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const ConstBufferSequence& source)
-{
-  return buffer_copy(static_cast<const mutable_buffer&>(target), source);
-}
+  /// Get a list of buffers that represents the output sequence, with the given
+  /// size.
+  /**
+   * Ensures that the output sequence can accommodate @c n bytes, resizing the
+   * basic_string object as necessary.
+   *
+   * @returns An object of type @c mutable_buffers_type that satisfies
+   * MutableBufferSequence requirements, representing basic_string memory
+   * at the start of the output sequence of size @c n.
+   *
+   * @throws std::length_error If <tt>size() + n > max_size()</tt>.
+   *
+   * @note The returned object is invalidated by any @c dynamic_string_buffer
+   * or @c basic_string member function that modifies the input sequence or
+   * output sequence.
+   */
+  mutable_buffers_type prepare(std::size_t n)
+  {
+    if (size () > max_size() || max_size() - size() < n)
+    {
+      std::length_error ex("dynamic_string_buffer too long");
+      boost::asio::detail::throw_exception(ex);
+    }
 
-/// Copies bytes from a source buffer to a target buffer sequence.
-/**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-template <typename MutableBufferSequence>
-std::size_t buffer_copy(const MutableBufferSequence& target,
-    const const_buffer& source)
-{
-  std::size_t total_bytes_copied = 0;
+    string_.resize(size_ + n);
 
-  typename MutableBufferSequence::const_iterator target_iter = target.begin();
-  typename MutableBufferSequence::const_iterator target_end = target.end();
+    return boost::asio::buffer(boost::asio::buffer(string_) + size_, n);
+  }
 
-  for (const_buffer source_buffer(source);
-      buffer_size(source_buffer) && target_iter != target_end; ++target_iter)
+  /// Move bytes from the output sequence to the input sequence.
+  /**
+   * @param n The number of bytes to append from the start of the output
+   * sequence to the end of the input sequence. The remainder of the output
+   * sequence is discarded.
+   *
+   * Requires a preceding call <tt>prepare(x)</tt> where <tt>x >= n</tt>, and
+   * no intervening operations that modify the input or output sequence.
+   *
+   * @note If @c n is greater than the size of the output sequence, the entire
+   * output sequence is moved to the input sequence and no error is issued.
+   */
+  void commit(std::size_t n)
   {
-    mutable_buffer target_buffer(*target_iter);
-    std::size_t bytes_copied = buffer_copy(target_buffer, source_buffer);
-    total_bytes_copied += bytes_copied;
-    source_buffer = source_buffer + bytes_copied;
+    size_ += (std::min)(n, string_.size() - size_);
+    string_.resize(size_);
   }
 
-  return total_bytes_copied;
-}
-
-/// Copies bytes from a source buffer to a target buffer sequence.
-/**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-template <typename MutableBufferSequence>
-inline std::size_t buffer_copy(const MutableBufferSequence& target,
-    const const_buffers_1& source)
-{
-  return buffer_copy(target, static_cast<const const_buffer&>(source));
-}
-
-/// Copies bytes from a source buffer to a target buffer sequence.
-/**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-template <typename MutableBufferSequence>
-inline std::size_t buffer_copy(const MutableBufferSequence& target,
-    const mutable_buffer& source)
-{
-  return buffer_copy(target, const_buffer(source));
-}
+  /// Remove characters from the input sequence.
+  /**
+   * Removes @c n characters from the beginning of the input sequence.
+   *
+   * @note If @c n is greater than the size of the input sequence, the entire
+   * input sequence is consumed and no error is issued.
+   */
+  void consume(std::size_t n)
+  {
+    std::size_t consume_length = (std::min)(n, size_);
+    string_.erase(0, consume_length);
+    size_ -= consume_length;
+  }
 
-/// Copies bytes from a source buffer to a target buffer sequence.
-/**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-template <typename MutableBufferSequence>
-inline std::size_t buffer_copy(const MutableBufferSequence& target,
-    const mutable_buffers_1& source)
-{
-  return buffer_copy(target, const_buffer(source));
-}
+private:
+  std::basic_string<Elem, Traits, Allocator>& string_;
+  std::size_t size_;
+  const std::size_t max_size_;
+};
 
-/// Copies bytes from a source buffer sequence to a target buffer sequence.
+/// Adapt a vector to the DynamicBuffer requirements.
 /**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
- *
- * @param source A non-modifiable buffer sequence representing the memory
- * regions from which the bytes will be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * Requires that <tt>sizeof(Elem) == 1</tt>.
  */
-template <typename MutableBufferSequence, typename ConstBufferSequence>
-std::size_t buffer_copy(const MutableBufferSequence& target,
-    const ConstBufferSequence& source)
+template <typename Elem, typename Allocator>
+class dynamic_vector_buffer
 {
-  std::size_t total_bytes_copied = 0;
-
-  typename MutableBufferSequence::const_iterator target_iter = target.begin();
-  typename MutableBufferSequence::const_iterator target_end = target.end();
-  std::size_t target_buffer_offset = 0;
+public:
+  /// The type used to represent the input sequence as a list of buffers.
+  typedef BOOST_ASIO_CONST_BUFFER const_buffers_type;
+
+  /// The type used to represent the output sequence as a list of buffers.
+  typedef BOOST_ASIO_MUTABLE_BUFFER mutable_buffers_type;
+
+  /// Construct a dynamic buffer from a string.
+  /**
+   * @param v The vector to be used as backing storage for the dynamic buffer.
+   * Any existing data in the vector is treated as the dynamic buffer's input
+   * sequence. The object stores a reference to the vector and the user is
+   * responsible for ensuring that the vector object remains valid until the
+   * dynamic_vector_buffer object is destroyed.
+   *
+   * @param maximum_size Specifies a maximum size for the buffer, in bytes.
+   */
+  explicit dynamic_vector_buffer(std::vector<Elem, Allocator>& v,
+      std::size_t maximum_size =
+        (std::numeric_limits<std::size_t>::max)()) BOOST_ASIO_NOEXCEPT
+    : vector_(v),
+      size_(vector_.size()),
+      max_size_(maximum_size)
+  {
+  }
 
-  typename ConstBufferSequence::const_iterator source_iter = source.begin();
-  typename ConstBufferSequence::const_iterator source_end = source.end();
-  std::size_t source_buffer_offset = 0;
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move construct a dynamic buffer.
+  dynamic_vector_buffer(dynamic_vector_buffer&& other) BOOST_ASIO_NOEXCEPT
+    : vector_(other.vector_),
+      size_(other.size_),
+      max_size_(other.max_size_)
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
-  while (target_iter != target_end && source_iter != source_end)
+  /// Get the size of the input sequence.
+  std::size_t size() const BOOST_ASIO_NOEXCEPT
   {
-    mutable_buffer target_buffer =
-      mutable_buffer(*target_iter) + target_buffer_offset;
+    return size_;
+  }
 
-    const_buffer source_buffer =
-      const_buffer(*source_iter) + source_buffer_offset;
+  /// Get the maximum size of the dynamic buffer.
+  /**
+   * @returns The allowed maximum of the sum of the sizes of the input sequence
+   * and output sequence.
+   */
+  std::size_t max_size() const BOOST_ASIO_NOEXCEPT
+  {
+    return max_size_;
+  }
 
-    std::size_t bytes_copied = buffer_copy(target_buffer, source_buffer);
-    total_bytes_copied += bytes_copied;
+  /// Get the current capacity of the dynamic buffer.
+  /**
+   * @returns The current total capacity of the buffer, i.e. for both the input
+   * sequence and output sequence.
+   */
+  std::size_t capacity() const BOOST_ASIO_NOEXCEPT
+  {
+    return vector_.capacity();
+  }
 
-    if (bytes_copied == buffer_size(target_buffer))
-    {
-      ++target_iter;
-      target_buffer_offset = 0;
-    }
-    else
-      target_buffer_offset += bytes_copied;
+  /// Get a list of buffers that represents the input sequence.
+  /**
+   * @returns An object of type @c const_buffers_type that satisfies
+   * ConstBufferSequence requirements, representing the basic_string memory in
+   * input sequence.
+   *
+   * @note The returned object is invalidated by any @c dynamic_vector_buffer
+   * or @c basic_string member function that modifies the input sequence or
+   * output sequence.
+   */
+  const_buffers_type data() const BOOST_ASIO_NOEXCEPT
+  {
+    return const_buffers_type(boost::asio::buffer(vector_, size_));
+  }
 
-    if (bytes_copied == buffer_size(source_buffer))
+  /// Get a list of buffers that represents the output sequence, with the given
+  /// size.
+  /**
+   * Ensures that the output sequence can accommodate @c n bytes, resizing the
+   * basic_string object as necessary.
+   *
+   * @returns An object of type @c mutable_buffers_type that satisfies
+   * MutableBufferSequence requirements, representing basic_string memory
+   * at the start of the output sequence of size @c n.
+   *
+   * @throws std::length_error If <tt>size() + n > max_size()</tt>.
+   *
+   * @note The returned object is invalidated by any @c dynamic_vector_buffer
+   * or @c basic_string member function that modifies the input sequence or
+   * output sequence.
+   */
+  mutable_buffers_type prepare(std::size_t n)
+  {
+    if (size () > max_size() || max_size() - size() < n)
     {
-      ++source_iter;
-      source_buffer_offset = 0;
+      std::length_error ex("dynamic_vector_buffer too long");
+      boost::asio::detail::throw_exception(ex);
     }
-    else
-      source_buffer_offset += bytes_copied;
-  }
 
-  return total_bytes_copied;
-}
+    vector_.resize(size_ + n);
 
-/// Copies a limited number of bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const const_buffer& source, std::size_t max_bytes_to_copy)
-{
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
-}
-
-/// Copies a limited number of bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const const_buffers_1& source, std::size_t max_bytes_to_copy)
-{
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
-}
-
-/// Copies a limited number of bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const mutable_buffer& source, std::size_t max_bytes_to_copy)
-{
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
-}
+    return boost::asio::buffer(boost::asio::buffer(vector_) + size_, n);
+  }
 
-/// Copies a limited number of bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const mutable_buffers_1& source, std::size_t max_bytes_to_copy)
-{
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
-}
+  /// Move bytes from the output sequence to the input sequence.
+  /**
+   * @param n The number of bytes to append from the start of the output
+   * sequence to the end of the input sequence. The remainder of the output
+   * sequence is discarded.
+   *
+   * Requires a preceding call <tt>prepare(x)</tt> where <tt>x >= n</tt>, and
+   * no intervening operations that modify the input or output sequence.
+   *
+   * @note If @c n is greater than the size of the output sequence, the entire
+   * output sequence is moved to the input sequence and no error is issued.
+   */
+  void commit(std::size_t n)
+  {
+    size_ += (std::min)(n, vector_.size() - size_);
+    vector_.resize(size_);
+  }
 
-/// Copies a limited number of bytes from a source buffer sequence to a target
-/// buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer sequence representing the memory
- * regions from which the bytes will be copied.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-template <typename ConstBufferSequence>
-inline std::size_t buffer_copy(const mutable_buffer& target,
-    const ConstBufferSequence& source, std::size_t max_bytes_to_copy)
-{
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
-}
+  /// Remove characters from the input sequence.
+  /**
+   * Removes @c n characters from the beginning of the input sequence.
+   *
+   * @note If @c n is greater than the size of the input sequence, the entire
+   * input sequence is consumed and no error is issued.
+   */
+  void consume(std::size_t n)
+  {
+    std::size_t consume_length = (std::min)(n, size_);
+    vector_.erase(vector_.begin(), vector_.begin() + consume_length);
+    size_ -= consume_length;
+  }
 
-/// Copies a limited number of bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const const_buffer& source, std::size_t max_bytes_to_copy)
-{
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
-}
+private:
+  std::vector<Elem, Allocator>& vector_;
+  std::size_t size_;
+  const std::size_t max_size_;
+};
 
-/// Copies a limited number of bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
+/** @defgroup dynamic_buffer boost::asio::dynamic_buffer
  *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * @brief The boost::asio::dynamic_buffer function is used to create a
+ * dynamically resized buffer from a @c std::basic_string or @c std::vector.
  */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const const_buffers_1& source, std::size_t max_bytes_to_copy)
-{
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
-}
+/*@{*/
 
-/// Copies a limited number of bytes from a source buffer to a target buffer.
-/**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+/// Create a new dynamic buffer that represents the given string.
+/**
+ * @returns <tt>dynamic_string_buffer<Elem, Traits, Allocator>(data)</tt>.
  */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const mutable_buffer& source, std::size_t max_bytes_to_copy)
+template <typename Elem, typename Traits, typename Allocator>
+inline dynamic_string_buffer<Elem, Traits, Allocator> dynamic_buffer(
+    std::basic_string<Elem, Traits, Allocator>& data) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
+  return dynamic_string_buffer<Elem, Traits, Allocator>(data);
 }
 
-/// Copies a limited number of bytes from a source buffer to a target buffer.
+/// Create a new dynamic buffer that represents the given string.
 /**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * @returns <tt>dynamic_string_buffer<Elem, Traits, Allocator>(data,
+ * max_size)</tt>.
  */
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const mutable_buffers_1& source, std::size_t max_bytes_to_copy)
+template <typename Elem, typename Traits, typename Allocator>
+inline dynamic_string_buffer<Elem, Traits, Allocator> dynamic_buffer(
+    std::basic_string<Elem, Traits, Allocator>& data,
+    std::size_t max_size) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
+  return dynamic_string_buffer<Elem, Traits, Allocator>(data, max_size);
 }
 
-/// Copies a limited number of bytes from a source buffer sequence to a target
-/// buffer.
+/// Create a new dynamic buffer that represents the given vector.
 /**
- * @param target A modifiable buffer representing the memory region to which
- * the bytes will be copied.
- *
- * @param source A non-modifiable buffer sequence representing the memory
- * regions from which the bytes will be copied.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * @returns <tt>dynamic_vector_buffer<Elem, Allocator>(data)</tt>.
  */
-template <typename ConstBufferSequence>
-inline std::size_t buffer_copy(const mutable_buffers_1& target,
-    const ConstBufferSequence& source, std::size_t max_bytes_to_copy)
+template <typename Elem, typename Allocator>
+inline dynamic_vector_buffer<Elem, Allocator> dynamic_buffer(
+    std::vector<Elem, Allocator>& data) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(buffer(target, max_bytes_to_copy), source);
+  return dynamic_vector_buffer<Elem, Allocator>(data);
 }
 
-/// Copies a limited number of bytes from a source buffer to a target buffer
-/// sequence.
+/// Create a new dynamic buffer that represents the given vector.
 /**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
- *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * @returns <tt>dynamic_vector_buffer<Elem, Allocator>(data, max_size)</tt>.
  */
-template <typename MutableBufferSequence>
-inline std::size_t buffer_copy(const MutableBufferSequence& target,
-    const const_buffer& source, std::size_t max_bytes_to_copy)
+template <typename Elem, typename Allocator>
+inline dynamic_vector_buffer<Elem, Allocator> dynamic_buffer(
+    std::vector<Elem, Allocator>& data,
+    std::size_t max_size) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(target, buffer(source, max_bytes_to_copy));
+  return dynamic_vector_buffer<Elem, Allocator>(data, max_size);
 }
 
-/// Copies a limited number of bytes from a source buffer to a target buffer
-/// sequence.
-/**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
+/*@}*/
+
+/** @defgroup buffer_copy boost::asio::buffer_copy
  *
- * @param source A non-modifiable buffer representing the memory region from
- * which the bytes will be copied.
+ * @brief The boost::asio::buffer_copy function is used to copy bytes from a
+ * source buffer (or buffer sequence) to a target buffer (or buffer sequence).
  *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
+ * The @c buffer_copy function is available in two forms:
  *
- * @returns The number of bytes copied.
+ * @li A 2-argument form: @c buffer_copy(target, source)
  *
- * @note The number of bytes copied is the lesser of:
+ * @li A 3-argument form: @c buffer_copy(target, source, max_bytes_to_copy)
+ *
+ * Both forms return the number of bytes actually copied. The number of bytes
+ * copied is the lesser of:
  *
  * @li @c buffer_size(target)
  *
  * @li @c buffer_size(source)
  *
- * @li @c max_bytes_to_copy
+ * @li @c If specified, @c max_bytes_to_copy.
  *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
+ * This prevents buffer overflow, regardless of the buffer sizes used in the
+ * copy operation.
+ *
+ * Note that @ref buffer_copy is implemented in terms of @c memcpy, and
+ * consequently it cannot be used to copy between overlapping memory regions.
  */
-template <typename MutableBufferSequence>
-inline std::size_t buffer_copy(const MutableBufferSequence& target,
-    const const_buffers_1& source, std::size_t max_bytes_to_copy)
+/*@{*/
+
+namespace detail {
+
+inline std::size_t buffer_copy_1(const mutable_buffer& target,
+    const const_buffer& source)
 {
-  return buffer_copy(target, buffer(source, max_bytes_to_copy));
+  using namespace std; // For memcpy.
+  std::size_t target_size = target.size();
+  std::size_t source_size = source.size();
+  std::size_t n = target_size < source_size ? target_size : source_size;
+  memcpy(target.data(), source.data(), n);
+  return n;
 }
 
-/// Copies a limited number of bytes from a source buffer to a target buffer
-/// sequence.
-/**
- * @param target A modifiable buffer sequence representing the memory regions to
- * which the bytes will be copied.
- *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
- *
- * @returns The number of bytes copied.
- *
- * @note The number of bytes copied is the lesser of:
- *
- * @li @c buffer_size(target)
- *
- * @li @c buffer_size(source)
- *
- * @li @c max_bytes_to_copy
- *
- * This function is implemented in terms of @c memcpy, and consequently it
- * cannot be used to copy between overlapping memory regions.
- */
-template <typename MutableBufferSequence>
-inline std::size_t buffer_copy(const MutableBufferSequence& target,
-    const mutable_buffer& source, std::size_t max_bytes_to_copy)
+template <typename TargetIterator, typename SourceIterator>
+inline std::size_t buffer_copy(one_buffer, one_buffer,
+    TargetIterator target_begin, TargetIterator,
+    SourceIterator source_begin, SourceIterator) BOOST_ASIO_NOEXCEPT
+{
+  return (buffer_copy_1)(*target_begin, *source_begin);
+}
+
+template <typename TargetIterator, typename SourceIterator>
+inline std::size_t buffer_copy(one_buffer, one_buffer,
+    TargetIterator target_begin, TargetIterator,
+    SourceIterator source_begin, SourceIterator,
+    std::size_t max_bytes_to_copy) BOOST_ASIO_NOEXCEPT
+{
+  return (buffer_copy_1)(*target_begin,
+      boost::asio::buffer(*source_begin, max_bytes_to_copy));
+}
+
+template <typename TargetIterator, typename SourceIterator>
+std::size_t buffer_copy(one_buffer, multiple_buffers,
+    TargetIterator target_begin, TargetIterator,
+    SourceIterator source_begin, SourceIterator source_end,
+    std::size_t max_bytes_to_copy
+      = (std::numeric_limits<std::size_t>::max)()) BOOST_ASIO_NOEXCEPT
+{
+  std::size_t total_bytes_copied = 0;
+  SourceIterator source_iter = source_begin;
+
+  for (mutable_buffer target_buffer(
+        boost::asio::buffer(*target_begin, max_bytes_to_copy));
+      target_buffer.size() && source_iter != source_end; ++source_iter)
+  {
+    const_buffer source_buffer(*source_iter);
+    std::size_t bytes_copied = (buffer_copy_1)(target_buffer, source_buffer);
+    total_bytes_copied += bytes_copied;
+    target_buffer += bytes_copied;
+  }
+
+  return total_bytes_copied;
+}
+
+template <typename TargetIterator, typename SourceIterator>
+std::size_t buffer_copy(multiple_buffers, one_buffer,
+    TargetIterator target_begin, TargetIterator target_end,
+    SourceIterator source_begin, SourceIterator,
+    std::size_t max_bytes_to_copy
+      = (std::numeric_limits<std::size_t>::max)()) BOOST_ASIO_NOEXCEPT
+{
+  std::size_t total_bytes_copied = 0;
+  TargetIterator target_iter = target_begin;
+
+  for (const_buffer source_buffer(
+        boost::asio::buffer(*source_begin, max_bytes_to_copy));
+      source_buffer.size() && target_iter != target_end; ++target_iter)
+  {
+    mutable_buffer target_buffer(*target_iter);
+    std::size_t bytes_copied = (buffer_copy_1)(target_buffer, source_buffer);
+    total_bytes_copied += bytes_copied;
+    source_buffer += bytes_copied;
+  }
+
+  return total_bytes_copied;
+}
+
+template <typename TargetIterator, typename SourceIterator>
+std::size_t buffer_copy(multiple_buffers, multiple_buffers,
+    TargetIterator target_begin, TargetIterator target_end,
+    SourceIterator source_begin, SourceIterator source_end) BOOST_ASIO_NOEXCEPT
+{
+  std::size_t total_bytes_copied = 0;
+
+  TargetIterator target_iter = target_begin;
+  std::size_t target_buffer_offset = 0;
+
+  SourceIterator source_iter = source_begin;
+  std::size_t source_buffer_offset = 0;
+
+  while (target_iter != target_end && source_iter != source_end)
+  {
+    mutable_buffer target_buffer =
+      mutable_buffer(*target_iter) + target_buffer_offset;
+
+    const_buffer source_buffer =
+      const_buffer(*source_iter) + source_buffer_offset;
+
+    std::size_t bytes_copied = (buffer_copy_1)(target_buffer, source_buffer);
+    total_bytes_copied += bytes_copied;
+
+    if (bytes_copied == target_buffer.size())
+    {
+      ++target_iter;
+      target_buffer_offset = 0;
+    }
+    else
+      target_buffer_offset += bytes_copied;
+
+    if (bytes_copied == source_buffer.size())
+    {
+      ++source_iter;
+      source_buffer_offset = 0;
+    }
+    else
+      source_buffer_offset += bytes_copied;
+  }
+
+  return total_bytes_copied;
+}
+
+template <typename TargetIterator, typename SourceIterator>
+std::size_t buffer_copy(multiple_buffers, multiple_buffers,
+    TargetIterator target_begin, TargetIterator target_end,
+    SourceIterator source_begin, SourceIterator source_end,
+    std::size_t max_bytes_to_copy) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(target, buffer(source, max_bytes_to_copy));
+  std::size_t total_bytes_copied = 0;
+
+  TargetIterator target_iter = target_begin;
+  std::size_t target_buffer_offset = 0;
+
+  SourceIterator source_iter = source_begin;
+  std::size_t source_buffer_offset = 0;
+
+  while (total_bytes_copied != max_bytes_to_copy
+      && target_iter != target_end && source_iter != source_end)
+  {
+    mutable_buffer target_buffer =
+      mutable_buffer(*target_iter) + target_buffer_offset;
+
+    const_buffer source_buffer =
+      const_buffer(*source_iter) + source_buffer_offset;
+
+    std::size_t bytes_copied = (buffer_copy_1)(
+        target_buffer, boost::asio::buffer(source_buffer,
+          max_bytes_to_copy - total_bytes_copied));
+    total_bytes_copied += bytes_copied;
+
+    if (bytes_copied == target_buffer.size())
+    {
+      ++target_iter;
+      target_buffer_offset = 0;
+    }
+    else
+      target_buffer_offset += bytes_copied;
+
+    if (bytes_copied == source_buffer.size())
+    {
+      ++source_iter;
+      source_buffer_offset = 0;
+    }
+    else
+      source_buffer_offset += bytes_copied;
+  }
+
+  return total_bytes_copied;
 }
 
-/// Copies a limited number of bytes from a source buffer to a target buffer
-/// sequence.
+} // namespace detail
+
+/// Copies bytes from a source buffer sequence to a target buffer sequence.
 /**
  * @param target A modifiable buffer sequence representing the memory regions to
  * which the bytes will be copied.
  *
- * @param source A modifiable buffer representing the memory region from which
- * the bytes will be copied. The contents of the source buffer will not be
- * modified.
- *
- * @param max_bytes_to_copy The maximum number of bytes to be copied.
+ * @param source A non-modifiable buffer sequence representing the memory
+ * regions from which the bytes will be copied.
  *
  * @returns The number of bytes copied.
  *
@@ -2148,16 +2099,20 @@ inline std::size_t buffer_copy(const MutableBufferSequence& target,
  *
  * @li @c buffer_size(source)
  *
- * @li @c max_bytes_to_copy
- *
  * This function is implemented in terms of @c memcpy, and consequently it
  * cannot be used to copy between overlapping memory regions.
  */
-template <typename MutableBufferSequence>
+template <typename MutableBufferSequence, typename ConstBufferSequence>
 inline std::size_t buffer_copy(const MutableBufferSequence& target,
-    const mutable_buffers_1& source, std::size_t max_bytes_to_copy)
+    const ConstBufferSequence& source) BOOST_ASIO_NOEXCEPT
 {
-  return buffer_copy(target, buffer(source, max_bytes_to_copy));
+  return detail::buffer_copy(
+      detail::buffer_sequence_cardinality<MutableBufferSequence>(),
+      detail::buffer_sequence_cardinality<ConstBufferSequence>(),
+      boost::asio::buffer_sequence_begin(target),
+      boost::asio::buffer_sequence_end(target),
+      boost::asio::buffer_sequence_begin(source),
+      boost::asio::buffer_sequence_end(source));
 }
 
 /// Copies a limited number of bytes from a source buffer sequence to a target
@@ -2185,50 +2140,17 @@ inline std::size_t buffer_copy(const MutableBufferSequence& target,
  * cannot be used to copy between overlapping memory regions.
  */
 template <typename MutableBufferSequence, typename ConstBufferSequence>
-std::size_t buffer_copy(const MutableBufferSequence& target,
-    const ConstBufferSequence& source, std::size_t max_bytes_to_copy)
-{
-  std::size_t total_bytes_copied = 0;
-
-  typename MutableBufferSequence::const_iterator target_iter = target.begin();
-  typename MutableBufferSequence::const_iterator target_end = target.end();
-  std::size_t target_buffer_offset = 0;
-
-  typename ConstBufferSequence::const_iterator source_iter = source.begin();
-  typename ConstBufferSequence::const_iterator source_end = source.end();
-  std::size_t source_buffer_offset = 0;
-
-  while (total_bytes_copied != max_bytes_to_copy
-      && target_iter != target_end && source_iter != source_end)
-  {
-    mutable_buffer target_buffer =
-      mutable_buffer(*target_iter) + target_buffer_offset;
-
-    const_buffer source_buffer =
-      const_buffer(*source_iter) + source_buffer_offset;
-
-    std::size_t bytes_copied = buffer_copy(target_buffer,
-        source_buffer, max_bytes_to_copy - total_bytes_copied);
-    total_bytes_copied += bytes_copied;
-
-    if (bytes_copied == buffer_size(target_buffer))
-    {
-      ++target_iter;
-      target_buffer_offset = 0;
-    }
-    else
-      target_buffer_offset += bytes_copied;
-
-    if (bytes_copied == buffer_size(source_buffer))
-    {
-      ++source_iter;
-      source_buffer_offset = 0;
-    }
-    else
-      source_buffer_offset += bytes_copied;
-  }
-
-  return total_bytes_copied;
+inline std::size_t buffer_copy(const MutableBufferSequence& target,
+    const ConstBufferSequence& source,
+    std::size_t max_bytes_to_copy) BOOST_ASIO_NOEXCEPT
+{
+  return detail::buffer_copy(
+      detail::buffer_sequence_cardinality<MutableBufferSequence>(),
+      detail::buffer_sequence_cardinality<ConstBufferSequence>(),
+      boost::asio::buffer_sequence_begin(target),
+      boost::asio::buffer_sequence_end(target),
+      boost::asio::buffer_sequence_begin(source),
+      boost::asio::buffer_sequence_end(source), max_bytes_to_copy);
 }
 
 /*@}*/
diff --git a/include/boost/asio/buffered_read_stream.hpp b/include/boost/asio/buffered_read_stream.hpp
index ece138b599..9774ee9d52 100644
--- a/include/boost/asio/buffered_read_stream.hpp
+++ b/include/boost/asio/buffered_read_stream.hpp
@@ -26,7 +26,7 @@
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -56,6 +56,9 @@ class buffered_read_stream
   /// The type of the lowest layer.
   typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
 
+  /// The type of the executor associated with the object.
+  typedef typename lowest_layer_type::executor_type executor_type;
+
 #if defined(GENERATING_DOCUMENTATION)
   /// The default buffer size.
   static const std::size_t default_buffer_size = implementation_defined;
@@ -97,11 +100,27 @@ class buffered_read_stream
     return next_layer_.lowest_layer();
   }
 
-  /// Get the io_service associated with the object.
-  boost::asio::io_service& get_io_service()
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return next_layer_.lowest_layer().get_executor();
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_context()
+  {
+    return next_layer_.get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_service()
   {
     return next_layer_.get_io_service();
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Close the stream.
   void close()
@@ -110,9 +129,10 @@ class buffered_read_stream
   }
 
   /// Close the stream.
-  boost::system::error_code close(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return next_layer_.close(ec);
+    next_layer_.close(ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Write the given data to the stream. Returns the number of bytes written.
@@ -140,15 +160,8 @@ class buffered_read_stream
   async_write_some(const ConstBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
+    return next_layer_.async_write_some(buffers,
         BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
-
-    next_layer_.async_write_some(buffers,
-        BOOST_ASIO_MOVE_CAST(BOOST_ASIO_HANDLER_TYPE(WriteHandler,
-            void (boost::system::error_code, std::size_t)))(init.handler));
-
-    return init.result.get();
   }
 
   /// Fill the buffer with some data. Returns the number of bytes placed in the
diff --git a/include/boost/asio/buffered_stream.hpp b/include/boost/asio/buffered_stream.hpp
index fae7c27113..a468370ffe 100644
--- a/include/boost/asio/buffered_stream.hpp
+++ b/include/boost/asio/buffered_stream.hpp
@@ -23,7 +23,7 @@
 #include <boost/asio/buffered_stream_fwd.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -53,6 +53,9 @@ class buffered_stream
   /// The type of the lowest layer.
   typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
 
+  /// The type of the executor associated with the object.
+  typedef typename lowest_layer_type::executor_type executor_type;
+
   /// Construct, passing the specified argument to initialise the next layer.
   template <typename Arg>
   explicit buffered_stream(Arg& a)
@@ -88,11 +91,27 @@ class buffered_stream
     return stream_impl_.lowest_layer();
   }
 
-  /// Get the io_service associated with the object.
-  boost::asio::io_service& get_io_service()
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return stream_impl_.lowest_layer().get_executor();
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_context()
+  {
+    return stream_impl_.get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_service()
   {
     return stream_impl_.get_io_service();
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Close the stream.
   void close()
@@ -101,9 +120,10 @@ class buffered_stream
   }
 
   /// Close the stream.
-  boost::system::error_code close(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return stream_impl_.close(ec);
+    stream_impl_.close(ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Flush all data from the buffer to the next layer. Returns the number of
diff --git a/include/boost/asio/buffered_write_stream.hpp b/include/boost/asio/buffered_write_stream.hpp
index 5b8f31378d..a1b9c44016 100644
--- a/include/boost/asio/buffered_write_stream.hpp
+++ b/include/boost/asio/buffered_write_stream.hpp
@@ -25,7 +25,7 @@
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/write.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -56,6 +56,9 @@ class buffered_write_stream
   /// The type of the lowest layer.
   typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
 
+  /// The type of the executor associated with the object.
+  typedef typename lowest_layer_type::executor_type executor_type;
+
 #if defined(GENERATING_DOCUMENTATION)
   /// The default buffer size.
   static const std::size_t default_buffer_size = implementation_defined;
@@ -97,11 +100,27 @@ class buffered_write_stream
     return next_layer_.lowest_layer();
   }
 
-  /// Get the io_service associated with the object.
-  boost::asio::io_service& get_io_service()
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return next_layer_.lowest_layer().get_executor();
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_context()
+  {
+    return next_layer_.get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_service()
   {
     return next_layer_.get_io_service();
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Close the stream.
   void close()
@@ -110,9 +129,10 @@ class buffered_write_stream
   }
 
   /// Close the stream.
-  boost::system::error_code close(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return next_layer_.close(ec);
+    next_layer_.close(ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Flush all data from the buffer to the next layer. Returns the number of
@@ -175,15 +195,8 @@ class buffered_write_stream
   async_read_some(const MutableBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
+    return next_layer_.async_read_some(buffers,
         BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
-
-    next_layer_.async_read_some(buffers,
-        BOOST_ASIO_MOVE_CAST(BOOST_ASIO_HANDLER_TYPE(ReadHandler,
-            void (boost::system::error_code, std::size_t)))(init.handler));
-
-    return init.result.get();
   }
 
   /// Peek at the incoming data on the stream. Returns the number of bytes read.
diff --git a/include/boost/asio/buffers_iterator.hpp b/include/boost/asio/buffers_iterator.hpp
index c64b341b5b..bebbca1b9e 100644
--- a/include/boost/asio/buffers_iterator.hpp
+++ b/include/boost/asio/buffers_iterator.hpp
@@ -66,7 +66,44 @@ namespace detail
     typedef buffers_iterator_types_helper<is_mutable> helper;
     typedef typename helper::buffer_type buffer_type;
     typedef typename helper::template byte_type<ByteType>::type byte_type;
+    typedef typename BufferSequence::const_iterator const_iterator;
   };
+
+  template <typename ByteType>
+  struct buffers_iterator_types<mutable_buffer, ByteType>
+  {
+    typedef mutable_buffer buffer_type;
+    typedef ByteType byte_type;
+    typedef const mutable_buffer* const_iterator;
+  };
+
+  template <typename ByteType>
+  struct buffers_iterator_types<const_buffer, ByteType>
+  {
+    typedef const_buffer buffer_type;
+    typedef typename add_const<ByteType>::type byte_type;
+    typedef const const_buffer* const_iterator;
+  };
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  template <typename ByteType>
+  struct buffers_iterator_types<mutable_buffers_1, ByteType>
+  {
+    typedef mutable_buffer buffer_type;
+    typedef ByteType byte_type;
+    typedef const mutable_buffer* const_iterator;
+  };
+
+  template <typename ByteType>
+  struct buffers_iterator_types<const_buffers_1, ByteType>
+  {
+    typedef const_buffer buffer_type;
+    typedef typename add_const<ByteType>::type byte_type;
+    typedef const const_buffer* const_iterator;
+  };
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 }
 
 /// A random access iterator over the bytes in a buffer sequence.
@@ -77,6 +114,9 @@ class buffers_iterator
   typedef typename detail::buffers_iterator_types<
       BufferSequence, ByteType>::buffer_type buffer_type;
 
+  typedef typename detail::buffers_iterator_types<BufferSequence,
+          ByteType>::const_iterator buffer_sequence_iterator_type;
+
 public:
   /// The type used for the distance between two iterators.
   typedef std::ptrdiff_t difference_type;
@@ -131,13 +171,13 @@ class buffers_iterator
 #endif // defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
   {
     buffers_iterator new_iter;
-    new_iter.begin_ = buffers.begin();
-    new_iter.current_ = buffers.begin();
-    new_iter.end_ = buffers.end();
+    new_iter.begin_ = boost::asio::buffer_sequence_begin(buffers);
+    new_iter.current_ = boost::asio::buffer_sequence_begin(buffers);
+    new_iter.end_ = boost::asio::buffer_sequence_end(buffers);
     while (new_iter.current_ != new_iter.end_)
     {
       new_iter.current_buffer_ = *new_iter.current_;
-      if (boost::asio::buffer_size(new_iter.current_buffer_) > 0)
+      if (new_iter.current_buffer_.size() > 0)
         break;
       ++new_iter.current_;
     }
@@ -151,13 +191,13 @@ class buffers_iterator
 #endif // defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 3)
   {
     buffers_iterator new_iter;
-    new_iter.begin_ = buffers.begin();
-    new_iter.current_ = buffers.begin();
-    new_iter.end_ = buffers.end();
+    new_iter.begin_ = boost::asio::buffer_sequence_begin(buffers);
+    new_iter.current_ = boost::asio::buffer_sequence_begin(buffers);
+    new_iter.end_ = boost::asio::buffer_sequence_end(buffers);
     while (new_iter.current_ != new_iter.end_)
     {
       buffer_type buffer = *new_iter.current_;
-      new_iter.position_ += boost::asio::buffer_size(buffer);
+      new_iter.position_ += buffer.size();
       ++new_iter.current_;
     }
     return new_iter;
@@ -301,7 +341,8 @@ class buffers_iterator
   // Dereference the iterator.
   reference dereference() const
   {
-    return buffer_cast<pointer>(current_buffer_)[current_buffer_position_];
+    return static_cast<pointer>(
+        current_buffer_.data())[current_buffer_position_];
   }
 
   // Compare two iterators for equality.
@@ -318,7 +359,7 @@ class buffers_iterator
 
     // Check if the increment can be satisfied by the current buffer.
     ++current_buffer_position_;
-    if (current_buffer_position_ != boost::asio::buffer_size(current_buffer_))
+    if (current_buffer_position_ != current_buffer_.size())
       return;
 
     // Find the next non-empty buffer.
@@ -327,7 +368,7 @@ class buffers_iterator
     while (current_ != end_)
     {
       current_buffer_ = *current_;
-      if (boost::asio::buffer_size(current_buffer_) > 0)
+      if (current_buffer_.size() > 0)
         return;
       ++current_;
     }
@@ -347,12 +388,12 @@ class buffers_iterator
     }
 
     // Find the previous non-empty buffer.
-    typename BufferSequence::const_iterator iter = current_;
+    buffer_sequence_iterator_type iter = current_;
     while (iter != begin_)
     {
       --iter;
       buffer_type buffer = *iter;
-      std::size_t buffer_size = boost::asio::buffer_size(buffer);
+      std::size_t buffer_size = buffer.size();
       if (buffer_size > 0)
       {
         current_ = iter;
@@ -372,8 +413,7 @@ class buffers_iterator
       for (;;)
       {
         std::ptrdiff_t current_buffer_balance
-          = boost::asio::buffer_size(current_buffer_)
-          - current_buffer_position_;
+          = current_buffer_.size() - current_buffer_position_;
 
         // Check if the advance can be satisfied by the current buffer.
         if (current_buffer_balance > n)
@@ -427,12 +467,12 @@ class buffers_iterator
         }
 
         // Find the previous non-empty buffer.
-        typename BufferSequence::const_iterator iter = current_;
+        buffer_sequence_iterator_type iter = current_;
         while (iter != begin_)
         {
           --iter;
           buffer_type buffer = *iter;
-          std::size_t buffer_size = boost::asio::buffer_size(buffer);
+          std::size_t buffer_size = buffer.size();
           if (buffer_size > 0)
           {
             current_ = iter;
@@ -453,9 +493,9 @@ class buffers_iterator
 
   buffer_type current_buffer_;
   std::size_t current_buffer_position_;
-  typename BufferSequence::const_iterator begin_;
-  typename BufferSequence::const_iterator current_;
-  typename BufferSequence::const_iterator end_;
+  buffer_sequence_iterator_type begin_;
+  buffer_sequence_iterator_type current_;
+  buffer_sequence_iterator_type end_;
   std::size_t position_;
 };
 
diff --git a/include/boost/asio/connect.hpp b/include/boost/asio/connect.hpp
index 635a8ad9bd..e31e8c92cd 100644
--- a/include/boost/asio/connect.hpp
+++ b/include/boost/asio/connect.hpp
@@ -18,6 +18,7 @@
 #include <boost/asio/detail/config.hpp>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/basic_socket.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -25,6 +26,36 @@
 namespace boost {
 namespace asio {
 
+namespace detail
+{
+  char (&has_iterator_helper(...))[2];
+
+  template <typename T>
+  char has_iterator_helper(T*, typename T::iterator* = 0);
+
+  template <typename T>
+  struct has_iterator_typedef
+  {
+    enum { value = (sizeof((has_iterator_helper)((T*)(0))) == 1) };
+  };
+} // namespace detail
+
+/// Type trait used to determine whether a type is an endpoint sequence that can
+/// be used with with @c connect and @c async_connect.
+template <typename T>
+struct is_endpoint_sequence
+{
+#if defined(GENERATING_DOCUMENTATION)
+  /// The value member is true if the type may be used as an endpoint sequence.
+  static const bool value;
+#else
+  enum
+  {
+    value = detail::has_iterator_typedef<T>::value
+  };
+#endif
+};
+
 /**
  * @defgroup connect boost::asio::connect
  *
@@ -42,27 +73,26 @@ namespace asio {
  * @param s The socket to be connected. If the socket is already open, it will
  * be closed.
  *
- * @param begin An iterator pointing to the start of a sequence of endpoints.
+ * @param endpoints A sequence of endpoints.
  *
- * @returns On success, an iterator denoting the successfully connected
- * endpoint. Otherwise, the end iterator.
+ * @returns The successfully connected endpoint.
  *
  * @throws boost::system::system_error Thrown on failure. If the sequence is
  * empty, the associated @c error_code is boost::asio::error::not_found.
  * Otherwise, contains the error from the last connection attempt.
  *
- * @note This overload assumes that a default constructed object of type @c
- * Iterator represents the end of the sequence. This is a valid assumption for
- * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
- *
  * @par Example
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
+ * tcp::socket s(io_context);
  * boost::asio::connect(s, r.resolve(q)); @endcode
  */
-template <typename Protocol, typename SocketService, typename Iterator>
-Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin);
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename EndpointSequence>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
 
 /// Establishes a socket connection by trying each endpoint in a sequence.
 /**
@@ -74,23 +104,19 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin);
  * @param s The socket to be connected. If the socket is already open, it will
  * be closed.
  *
- * @param begin An iterator pointing to the start of a sequence of endpoints.
+ * @param endpoints A sequence of endpoints.
  *
  * @param ec Set to indicate what error occurred, if any. If the sequence is
  * empty, set to boost::asio::error::not_found. Otherwise, contains the error
  * from the last connection attempt.
  *
- * @returns On success, an iterator denoting the successfully connected
- * endpoint. Otherwise, the end iterator.
- *
- * @note This overload assumes that a default constructed object of type @c
- * Iterator represents the end of the sequence. This is a valid assumption for
- * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ * @returns On success, the successfully connected endpoint. Otherwise, a
+ * default-constructed endpoint.
  *
  * @par Example
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
+ * tcp::socket s(io_context);
  * boost::system::error_code ec;
  * boost::asio::connect(s, r.resolve(q), ec);
  * if (ec)
@@ -98,11 +124,16 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin);
  *   // An error occurred.
  * } @endcode
  */
-template <typename Protocol, typename SocketService, typename Iterator>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
-    Iterator begin, boost::system::error_code& ec);
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename EndpointSequence>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, boost::system::error_code& ec,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
 
-/// Establishes a socket connection by trying each endpoint in a sequence.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
 /**
  * This function attempts to connect a socket to one of a sequence of
  * endpoints. It does this by repeated calls to the socket's @c connect member
@@ -114,24 +145,80 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  *
  * @param begin An iterator pointing to the start of a sequence of endpoints.
  *
- * @param end An iterator pointing to the end of a sequence of endpoints.
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @throws boost::system::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is boost::asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s, Iterator begin,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to boost::asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
  *
  * @returns On success, an iterator denoting the successfully connected
  * endpoint. Otherwise, the end iterator.
  *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    Iterator begin, boost::system::error_code& ec,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+/// Establishes a socket connection by trying each endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param end An iterator pointing to the end of a sequence of endpoints.
+ *
+ * @returns An iterator denoting the successfully connected endpoint.
+ *
  * @throws boost::system::system_error Thrown on failure. If the sequence is
  * empty, the associated @c error_code is boost::asio::error::not_found.
  * Otherwise, contains the error from the last connection attempt.
  *
  * @par Example
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::resolver::iterator i = r.resolve(q), end;
- * tcp::socket s(io_service);
- * boost::asio::connect(s, i, end); @endcode
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
+ * boost::asio::connect(s, e.begin(), e.end()); @endcode
  */
-template <typename Protocol, typename SocketService, typename Iterator>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end);
 
 /// Establishes a socket connection by trying each endpoint in a sequence.
@@ -156,19 +243,19 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  * endpoint. Otherwise, the end iterator.
  *
  * @par Example
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::resolver::iterator i = r.resolve(q), end;
- * tcp::socket s(io_service);
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
  * boost::system::error_code ec;
- * boost::asio::connect(s, i, end, ec);
+ * boost::asio::connect(s, e.begin(), e.end(), ec);
  * if (ec)
  * {
  *   // An error occurred.
  * } @endcode
  */
-template <typename Protocol, typename SocketService, typename Iterator>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end, boost::system::error_code& ec);
 
 /// Establishes a socket connection by trying each endpoint in a sequence.
@@ -181,59 +268,54 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  * @param s The socket to be connected. If the socket is already open, it will
  * be closed.
  *
- * @param begin An iterator pointing to the start of a sequence of endpoints.
+ * @param endpoints A sequence of endpoints.
  *
  * @param connect_condition A function object that is called prior to each
  * connection attempt. The signature of the function object must be:
- * @code Iterator connect_condition(
+ * @code bool connect_condition(
  *     const boost::system::error_code& ec,
- *     Iterator next); @endcode
+ *     const typename Protocol::endpoint& next); @endcode
  * The @c ec parameter contains the result from the most recent connect
  * operation. Before the first connection attempt, @c ec is always set to
- * indicate success. The @c next parameter is an iterator pointing to the next
- * endpoint to be tried. The function object should return the next iterator,
- * but is permitted to return a different iterator so that endpoints may be
- * skipped. The implementation guarantees that the function object will never
- * be called with the end iterator.
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
  *
- * @returns On success, an iterator denoting the successfully connected
- * endpoint. Otherwise, the end iterator.
+ * @returns The successfully connected endpoint.
  *
  * @throws boost::system::system_error Thrown on failure. If the sequence is
  * empty, the associated @c error_code is boost::asio::error::not_found.
  * Otherwise, contains the error from the last connection attempt.
  *
- * @note This overload assumes that a default constructed object of type @c
- * Iterator represents the end of the sequence. This is a valid assumption for
- * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
- *
  * @par Example
  * The following connect condition function object can be used to output
  * information about the individual connection attempts:
  * @code struct my_connect_condition
  * {
- *   template <typename Iterator>
- *   Iterator operator()(
+ *   bool operator()(
  *       const boost::system::error_code& ec,
- *       Iterator next)
+ *       const::tcp::endpoint& next)
  *   {
  *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
- *     std::cout << "Trying: " << next->endpoint() << std::endl;
- *     return next;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
  *   }
  * }; @endcode
  * It would be used with the boost::asio::connect function as follows:
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
- * tcp::resolver::iterator i = boost::asio::connect(
- *     s, r.resolve(q), my_connect_condition());
- * std::cout << "Connected to: " << i->endpoint() << std::endl; @endcode
+ * tcp::socket s(io_context);
+ * tcp::endpoint e = boost::asio::connect(s,
+ *     r.resolve(q), my_connect_condition());
+ * std::cout << "Connected to: " << e << std::endl; @endcode
  */
-template <typename Protocol, typename SocketService,
-    typename Iterator, typename ConnectCondition>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
-    Iterator begin, ConnectCondition connect_condition);
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
 
 /// Establishes a socket connection by trying each endpoint in a sequence.
 /**
@@ -245,67 +327,148 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  * @param s The socket to be connected. If the socket is already open, it will
  * be closed.
  *
- * @param begin An iterator pointing to the start of a sequence of endpoints.
+ * @param endpoints A sequence of endpoints.
  *
  * @param connect_condition A function object that is called prior to each
  * connection attempt. The signature of the function object must be:
- * @code Iterator connect_condition(
+ * @code bool connect_condition(
  *     const boost::system::error_code& ec,
- *     Iterator next); @endcode
+ *     const typename Protocol::endpoint& next); @endcode
  * The @c ec parameter contains the result from the most recent connect
  * operation. Before the first connection attempt, @c ec is always set to
- * indicate success. The @c next parameter is an iterator pointing to the next
- * endpoint to be tried. The function object should return the next iterator,
- * but is permitted to return a different iterator so that endpoints may be
- * skipped. The implementation guarantees that the function object will never
- * be called with the end iterator.
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
  *
  * @param ec Set to indicate what error occurred, if any. If the sequence is
  * empty, set to boost::asio::error::not_found. Otherwise, contains the error
  * from the last connection attempt.
  *
- * @returns On success, an iterator denoting the successfully connected
- * endpoint. Otherwise, the end iterator.
- *
- * @note This overload assumes that a default constructed object of type @c
- * Iterator represents the end of the sequence. This is a valid assumption for
- * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ * @returns On success, the successfully connected endpoint. Otherwise, a
+ * default-constructed endpoint.
  *
  * @par Example
  * The following connect condition function object can be used to output
  * information about the individual connection attempts:
  * @code struct my_connect_condition
  * {
- *   template <typename Iterator>
- *   Iterator operator()(
+ *   bool operator()(
  *       const boost::system::error_code& ec,
- *       Iterator next)
+ *       const::tcp::endpoint& next)
  *   {
  *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
- *     std::cout << "Trying: " << next->endpoint() << std::endl;
- *     return next;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
  *   }
  * }; @endcode
  * It would be used with the boost::asio::connect function as follows:
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
+ * tcp::socket s(io_context);
  * boost::system::error_code ec;
- * tcp::resolver::iterator i = boost::asio::connect(
- *     s, r.resolve(q), my_connect_condition(), ec);
+ * tcp::endpoint e = boost::asio::connect(s,
+ *     r.resolve(q), my_connect_condition(), ec);
  * if (ec)
  * {
  *   // An error occurred.
  * }
  * else
  * {
- *   std::cout << "Connected to: " << i->endpoint() << std::endl;
+ *   std::cout << "Connected to: " << e << std::endl;
  * } @endcode
  */
-template <typename Protocol, typename SocketService,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    boost::system::error_code& ec,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const boost::system::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @throws boost::system::system_error Thrown on failure. If the sequence is
+ * empty, the associated @c error_code is boost::asio::error::not_found.
+ * Otherwise, contains the error from the last connection attempt.
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
     typename Iterator, typename ConnectCondition>
-Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
-    ConnectCondition connect_condition, boost::system::error_code& ec);
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    Iterator begin, ConnectCondition connect_condition,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+
+/// (Deprecated.) Establishes a socket connection by trying each endpoint in a
+/// sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c connect member
+ * function, once for each endpoint in the sequence, until a connection is
+ * successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const boost::system::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param ec Set to indicate what error occurred, if any. If the sequence is
+ * empty, set to boost::asio::error::not_found. Otherwise, contains the error
+ * from the last connection attempt.
+ *
+ * @returns On success, an iterator denoting the successfully connected
+ * endpoint. Otherwise, the end iterator.
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Iterator, typename ConnectCondition>
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s, Iterator begin,
+    ConnectCondition connect_condition, boost::system::error_code& ec,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 /// Establishes a socket connection by trying each endpoint in a sequence.
 /**
@@ -323,19 +486,16 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  *
  * @param connect_condition A function object that is called prior to each
  * connection attempt. The signature of the function object must be:
- * @code Iterator connect_condition(
+ * @code bool connect_condition(
  *     const boost::system::error_code& ec,
- *     Iterator next); @endcode
+ *     const typename Protocol::endpoint& next); @endcode
  * The @c ec parameter contains the result from the most recent connect
  * operation. Before the first connection attempt, @c ec is always set to
- * indicate success. The @c next parameter is an iterator pointing to the next
- * endpoint to be tried. The function object should return the next iterator,
- * but is permitted to return a different iterator so that endpoints may be
- * skipped. The implementation guarantees that the function object will never
- * be called with the end iterator.
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
  *
- * @returns On success, an iterator denoting the successfully connected
- * endpoint. Otherwise, the end iterator.
+ * @returns An iterator denoting the successfully connected endpoint.
  *
  * @throws boost::system::system_error Thrown on failure. If the sequence is
  * empty, the associated @c error_code is boost::asio::error::not_found.
@@ -346,27 +506,27 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  * information about the individual connection attempts:
  * @code struct my_connect_condition
  * {
- *   template <typename Iterator>
- *   Iterator operator()(
+ *   bool operator()(
  *       const boost::system::error_code& ec,
- *       Iterator next)
+ *       const::tcp::endpoint& next)
  *   {
  *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
- *     std::cout << "Trying: " << next->endpoint() << std::endl;
- *     return next;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
  *   }
  * }; @endcode
  * It would be used with the boost::asio::connect function as follows:
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::resolver::iterator i = r.resolve(q), end;
- * tcp::socket s(io_service);
- * i = boost::asio::connect(s, i, end, my_connect_condition());
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
+ * tcp::resolver::results_type::iterator i = boost::asio::connect(
+ *     s, e.begin(), e.end(), my_connect_condition());
  * std::cout << "Connected to: " << i->endpoint() << std::endl; @endcode
  */
-template <typename Protocol, typename SocketService,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
     typename Iterator, typename ConnectCondition>
-Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s, Iterator begin,
     Iterator end, ConnectCondition connect_condition);
 
 /// Establishes a socket connection by trying each endpoint in a sequence.
@@ -385,16 +545,14 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  *
  * @param connect_condition A function object that is called prior to each
  * connection attempt. The signature of the function object must be:
- * @code Iterator connect_condition(
+ * @code bool connect_condition(
  *     const boost::system::error_code& ec,
- *     Iterator next); @endcode
+ *     const typename Protocol::endpoint& next); @endcode
  * The @c ec parameter contains the result from the most recent connect
  * operation. Before the first connection attempt, @c ec is always set to
- * indicate success. The @c next parameter is an iterator pointing to the next
- * endpoint to be tried. The function object should return the next iterator,
- * but is permitted to return a different iterator so that endpoints may be
- * skipped. The implementation guarantees that the function object will never
- * be called with the end iterator.
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
  *
  * @param ec Set to indicate what error occurred, if any. If the sequence is
  * empty, set to boost::asio::error::not_found. Otherwise, contains the error
@@ -408,23 +566,23 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  * information about the individual connection attempts:
  * @code struct my_connect_condition
  * {
- *   template <typename Iterator>
- *   Iterator operator()(
+ *   bool operator()(
  *       const boost::system::error_code& ec,
- *       Iterator next)
+ *       const::tcp::endpoint& next)
  *   {
  *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
- *     std::cout << "Trying: " << next->endpoint() << std::endl;
- *     return next;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
  *   }
  * }; @endcode
  * It would be used with the boost::asio::connect function as follows:
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::resolver::iterator i = r.resolve(q), end;
- * tcp::socket s(io_service);
+ * tcp::resolver::results_type e = r.resolve(q);
+ * tcp::socket s(io_context);
  * boost::system::error_code ec;
- * i = boost::asio::connect(s, i, end, my_connect_condition(), ec);
+ * tcp::resolver::results_type::iterator i = boost::asio::connect(
+ *     s, e.begin(), e.end(), my_connect_condition());
  * if (ec)
  * {
  *   // An error occurred.
@@ -434,9 +592,9 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  *   std::cout << "Connected to: " << i->endpoint() << std::endl;
  * } @endcode
  */
-template <typename Protocol, typename SocketService,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
     typename Iterator, typename ConnectCondition>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end, ConnectCondition connect_condition,
     boost::system::error_code& ec);
 
@@ -461,7 +619,7 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  * @param s The socket to be connected. If the socket is already open, it will
  * be closed.
  *
- * @param begin An iterator pointing to the start of a sequence of endpoints.
+ * @param endpoints A sequence of endpoints.
  *
  * @param handler The handler to be called when the connect operation
  * completes. Copies will be made of the handler as required. The function
@@ -472,23 +630,19 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  *   // error from the last connection attempt.
  *   const boost::system::error_code& error,
  *
- *   // On success, an iterator denoting the successfully
- *   // connected endpoint. Otherwise, the end iterator.
- *   Iterator iterator
+ *   // On success, the successfully connected endpoint.
+ *   // Otherwise, a default-constructed endpoint.
+ *   const typename Protocol::endpoint& endpoint
  * ); @endcode
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation
  * of the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
- *
- * @note This overload assumes that a default constructed object of type @c
- * Iterator represents the end of the sequence. This is a valid assumption for
- * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ * boost::asio::io_context::post().
  *
  * @par Example
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
+ * tcp::socket s(io_context);
  *
  * // ...
  *
@@ -498,11 +652,11 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  *
  * void resolve_handler(
  *     const boost::system::error_code& ec,
- *     tcp::resolver::iterator i)
+ *     tcp::resolver::results_type results)
  * {
  *   if (!ec)
  *   {
- *     boost::asio::async_connect(s, i, connect_handler);
+ *     boost::asio::async_connect(s, results, connect_handler);
  *   }
  * }
  *
@@ -510,17 +664,65 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
  *
  * void connect_handler(
  *     const boost::system::error_code& ec,
- *     tcp::resolver::iterator i)
+ *     const tcp::endpoint& endpoint)
  * {
  *   // ...
  * } @endcode
  */
-template <typename Protocol, typename SocketService,
-    typename Iterator, typename ComposedConnectHandler>
-BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename RangeConnectHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(RangeConnectHandler,
+    void (boost::system::error_code, typename Protocol::endpoint))
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints,
+    BOOST_ASIO_MOVE_ARG(RangeConnectHandler) handler,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+/// (Deprecated.) Asynchronously establishes a socket connection by trying each
+/// endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // boost::asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const boost::system::error_code& error,
+ *
+ *   // On success, an iterator denoting the successfully
+ *   // connected endpoint. Otherwise, the end iterator.
+ *   Iterator iterator
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Iterator, typename IteratorConnectHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s,
-    Iterator begin, BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler);
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    Iterator begin, BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 /// Asynchronously establishes a socket connection by trying each endpoint in a
 /// sequence.
@@ -553,46 +755,31 @@ async_connect(basic_socket<Protocol, SocketService>& s,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation
  * of the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
- * @code tcp::resolver r(io_service);
- * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
- *
- * // ...
- *
- * r.async_resolve(q, resolve_handler);
- *
- * // ...
- *
- * void resolve_handler(
- *     const boost::system::error_code& ec,
- *     tcp::resolver::iterator i)
- * {
- *   if (!ec)
- *   {
- *     tcp::resolver::iterator end;
- *     boost::asio::async_connect(s, i, end, connect_handler);
- *   }
- * }
+ * @code std::vector<tcp::endpoint> endpoints = ...;
+ * tcp::socket s(io_context);
+ * boost::asio::async_connect(s,
+ *     endpoints.begin(), endpoints.end(),
+ *     connect_handler);
  *
  * // ...
  *
  * void connect_handler(
  *     const boost::system::error_code& ec,
- *     tcp::resolver::iterator i)
+ *     std::vector<tcp::endpoint>::iterator i)
  * {
  *   // ...
  * } @endcode
  */
-template <typename Protocol, typename SocketService,
-    typename Iterator, typename ComposedConnectHandler>
-BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Iterator, typename IteratorConnectHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s,
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end,
-    BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler);
+    BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler);
 
 /// Asynchronously establishes a socket connection by trying each endpoint in a
 /// sequence.
@@ -605,20 +792,18 @@ async_connect(basic_socket<Protocol, SocketService>& s,
  * @param s The socket to be connected. If the socket is already open, it will
  * be closed.
  *
- * @param begin An iterator pointing to the start of a sequence of endpoints.
+ * @param endpoints A sequence of endpoints.
  *
  * @param connect_condition A function object that is called prior to each
  * connection attempt. The signature of the function object must be:
- * @code Iterator connect_condition(
+ * @code bool connect_condition(
  *     const boost::system::error_code& ec,
- *     Iterator next); @endcode
+ *     const typename Protocol::endpoint& next); @endcode
  * The @c ec parameter contains the result from the most recent connect
  * operation. Before the first connection attempt, @c ec is always set to
- * indicate success. The @c next parameter is an iterator pointing to the next
- * endpoint to be tried. The function object should return the next iterator,
- * but is permitted to return a different iterator so that endpoints may be
- * skipped. The implementation guarantees that the function object will never
- * be called with the end iterator.
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
  *
  * @param handler The handler to be called when the connect operation
  * completes. Copies will be made of the handler as required. The function
@@ -636,31 +821,26 @@ async_connect(basic_socket<Protocol, SocketService>& s,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation
  * of the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
- *
- * @note This overload assumes that a default constructed object of type @c
- * Iterator represents the end of the sequence. This is a valid assumption for
- * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ * boost::asio::io_context::post().
  *
  * @par Example
  * The following connect condition function object can be used to output
  * information about the individual connection attempts:
  * @code struct my_connect_condition
  * {
- *   template <typename Iterator>
- *   Iterator operator()(
+ *   bool operator()(
  *       const boost::system::error_code& ec,
- *       Iterator next)
+ *       const::tcp::endpoint& next)
  *   {
  *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
- *     std::cout << "Trying: " << next->endpoint() << std::endl;
- *     return next;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
  *   }
  * }; @endcode
  * It would be used with the boost::asio::connect function as follows:
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
+ * tcp::socket s(io_context);
  *
  * // ...
  *
@@ -670,11 +850,11 @@ async_connect(basic_socket<Protocol, SocketService>& s,
  *
  * void resolve_handler(
  *     const boost::system::error_code& ec,
- *     tcp::resolver::iterator i)
+ *     tcp::resolver::results_type results)
  * {
  *   if (!ec)
  *   {
- *     boost::asio::async_connect(s, i,
+ *     boost::asio::async_connect(s, results,
  *         my_connect_condition(),
  *         connect_handler);
  *   }
@@ -684,7 +864,7 @@ async_connect(basic_socket<Protocol, SocketService>& s,
  *
  * void connect_handler(
  *     const boost::system::error_code& ec,
- *     tcp::resolver::iterator i)
+ *     const tcp::endpoint& endpoint)
  * {
  *   if (ec)
  *   {
@@ -692,17 +872,76 @@ async_connect(basic_socket<Protocol, SocketService>& s,
  *   }
  *   else
  *   {
- *     std::cout << "Connected to: " << i->endpoint() << std::endl;
+ *     std::cout << "Connected to: " << endpoint << std::endl;
  *   }
  * } @endcode
  */
-template <typename Protocol, typename SocketService, typename Iterator,
-    typename ConnectCondition, typename ComposedConnectHandler>
-BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename EndpointSequence,
+    typename ConnectCondition, typename RangeConnectHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(RangeConnectHandler,
+    void (boost::system::error_code, typename Protocol::endpoint))
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    BOOST_ASIO_MOVE_ARG(RangeConnectHandler) handler,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type* = 0);
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+/// (Deprecated.) Asynchronously establishes a socket connection by trying each
+/// endpoint in a sequence.
+/**
+ * This function attempts to connect a socket to one of a sequence of
+ * endpoints. It does this by repeated calls to the socket's @c async_connect
+ * member function, once for each endpoint in the sequence, until a connection
+ * is successfully established.
+ *
+ * @param s The socket to be connected. If the socket is already open, it will
+ * be closed.
+ *
+ * @param begin An iterator pointing to the start of a sequence of endpoints.
+ *
+ * @param connect_condition A function object that is called prior to each
+ * connection attempt. The signature of the function object must be:
+ * @code bool connect_condition(
+ *     const boost::system::error_code& ec,
+ *     const typename Protocol::endpoint& next); @endcode
+ * The @c ec parameter contains the result from the most recent connect
+ * operation. Before the first connection attempt, @c ec is always set to
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
+ *
+ * @param handler The handler to be called when the connect operation
+ * completes. Copies will be made of the handler as required. The function
+ * signature of the handler must be:
+ * @code void handler(
+ *   // Result of operation. if the sequence is empty, set to
+ *   // boost::asio::error::not_found. Otherwise, contains the
+ *   // error from the last connection attempt.
+ *   const boost::system::error_code& error,
+ *
+ *   // On success, an iterator denoting the successfully
+ *   // connected endpoint. Otherwise, the end iterator.
+ *   Iterator iterator
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation
+ * of the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
+ *
+ * @note This overload assumes that a default constructed object of type @c
+ * Iterator represents the end of the sequence. This is a valid assumption for
+ * iterator types such as @c boost::asio::ip::tcp::resolver::iterator.
+ */
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+    typename ConnectCondition, typename IteratorConnectHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s, Iterator begin,
     ConnectCondition connect_condition,
-    BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler);
+    BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type* = 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 /// Asynchronously establishes a socket connection by trying each endpoint in a
 /// sequence.
@@ -721,16 +960,14 @@ async_connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  *
  * @param connect_condition A function object that is called prior to each
  * connection attempt. The signature of the function object must be:
- * @code Iterator connect_condition(
+ * @code bool connect_condition(
  *     const boost::system::error_code& ec,
- *     Iterator next); @endcode
+ *     const typename Protocol::endpoint& next); @endcode
  * The @c ec parameter contains the result from the most recent connect
  * operation. Before the first connection attempt, @c ec is always set to
- * indicate success. The @c next parameter is an iterator pointing to the next
- * endpoint to be tried. The function object should return the next iterator,
- * but is permitted to return a different iterator so that endpoints may be
- * skipped. The implementation guarantees that the function object will never
- * be called with the end iterator.
+ * indicate success. The @c next parameter is the next endpoint to be tried.
+ * The function object should return true if the next endpoint should be tried,
+ * and false if it should be skipped.
  *
  * @param handler The handler to be called when the connect operation
  * completes. Copies will be made of the handler as required. The function
@@ -748,27 +985,26 @@ async_connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation
  * of the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * The following connect condition function object can be used to output
  * information about the individual connection attempts:
  * @code struct my_connect_condition
  * {
- *   template <typename Iterator>
- *   Iterator operator()(
+ *   bool operator()(
  *       const boost::system::error_code& ec,
- *       Iterator next)
+ *       const::tcp::endpoint& next)
  *   {
  *     if (ec) std::cout << "Error: " << ec.message() << std::endl;
- *     std::cout << "Trying: " << next->endpoint() << std::endl;
- *     return next;
+ *     std::cout << "Trying: " << next << std::endl;
+ *     return true;
  *   }
  * }; @endcode
  * It would be used with the boost::asio::connect function as follows:
- * @code tcp::resolver r(io_service);
+ * @code tcp::resolver r(io_context);
  * tcp::resolver::query q("host", "service");
- * tcp::socket s(io_service);
+ * tcp::socket s(io_context);
  *
  * // ...
  *
@@ -805,13 +1041,13 @@ async_connect(basic_socket<Protocol, SocketService>& s, Iterator begin,
  *   }
  * } @endcode
  */
-template <typename Protocol, typename SocketService, typename Iterator,
-    typename ConnectCondition, typename ComposedConnectHandler>
-BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+    typename ConnectCondition, typename IteratorConnectHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s,
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end, ConnectCondition connect_condition,
-    BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler);
+    BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler);
 
 /*@}*/
 
diff --git a/include/boost/asio/coroutine.hpp b/include/boost/asio/coroutine.hpp
index c4763f8524..a289b4b6c1 100644
--- a/include/boost/asio/coroutine.hpp
+++ b/include/boost/asio/coroutine.hpp
@@ -206,7 +206,7 @@ class coroutine_ref;
  * {
  *   do
  *   {
- *     socket_.reset(new tcp::socket(io_service_));
+ *     socket_.reset(new tcp::socket(io_context_));
  *     yield acceptor->async_accept(*socket_, *this);
  *     fork server(*this)();
  *   } while (is_parent());
@@ -228,7 +228,7 @@ class coroutine_ref;
  * Note that @c fork doesn't do the actual forking by itself. It is the
  * application's responsibility to create a clone of the coroutine and call it.
  * The clone can be called immediately, as above, or scheduled for delayed
- * execution using something like io_service::post().
+ * execution using something like io_context::post().
  *
  * @par Alternate macro names
  *
diff --git a/include/boost/asio/datagram_socket_service.hpp b/include/boost/asio/datagram_socket_service.hpp
index 95f179acfd..35bc2f5feb 100644
--- a/include/boost/asio/datagram_socket_service.hpp
+++ b/include/boost/asio/datagram_socket_service.hpp
@@ -16,11 +16,14 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/null_socket_service.hpp>
@@ -39,7 +42,7 @@ namespace asio {
 template <typename Protocol>
 class datagram_socket_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<datagram_socket_service<Protocol> >
 #endif
@@ -47,7 +50,7 @@ class datagram_socket_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The protocol type.
@@ -74,13 +77,6 @@ class datagram_socket_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native socket type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef typename service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native socket type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -88,11 +84,11 @@ class datagram_socket_service
   typedef typename service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new datagram socket service for the specified io_service.
-  explicit datagram_socket_service(boost::asio::io_service& io_service)
+  /// Construct a new datagram socket service for the specified io_context.
+  explicit datagram_socket_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        datagram_socket_service<Protocol> >(io_service),
-      service_impl_(io_service)
+        datagram_socket_service<Protocol> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -143,22 +139,23 @@ class datagram_socket_service
   }
 
   // Open a new datagram socket implementation.
-  boost::system::error_code open(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID open(implementation_type& impl,
       const protocol_type& protocol, boost::system::error_code& ec)
   {
     if (protocol.type() == BOOST_ASIO_OS_DEF(SOCK_DGRAM))
       service_impl_.open(impl, protocol, ec);
     else
       ec = boost::asio::error::invalid_argument;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native socket to a datagram socket.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const protocol_type& protocol, const native_handle_type& native_socket,
       boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, protocol, native_socket, ec);
+    service_impl_.assign(impl, protocol, native_socket, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is open.
@@ -168,16 +165,18 @@ class datagram_socket_service
   }
 
   /// Close a datagram socket implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  /// (Deprecated: Use native_handle().) Get the native socket implementation.
-  native_type native(implementation_type& impl)
+  /// Release ownership of the underlying socket.
+  native_handle_type release(implementation_type& impl,
+      boost::system::error_code& ec)
   {
-    return service_impl_.native_handle(impl);
+    return service_impl_.release(impl, ec);
   }
 
   /// Get the native socket implementation.
@@ -187,10 +186,11 @@ class datagram_socket_service
   }
 
   /// Cancel all asynchronous operations associated with the socket.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is at the out-of-band data mark.
@@ -208,17 +208,19 @@ class datagram_socket_service
   }
 
   // Bind the datagram socket to the specified local endpoint.
-  boost::system::error_code bind(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID bind(implementation_type& impl,
       const endpoint_type& endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.bind(impl, endpoint, ec);
+    service_impl_.bind(impl, endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Connect the datagram socket to the specified endpoint.
-  boost::system::error_code connect(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID connect(implementation_type& impl,
       const endpoint_type& peer_endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.connect(impl, peer_endpoint, ec);
+    service_impl_.connect(impl, peer_endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous connect.
@@ -229,37 +231,39 @@ class datagram_socket_service
       const endpoint_type& peer_endpoint,
       BOOST_ASIO_MOVE_ARG(ConnectHandler) handler)
   {
-    detail::async_result_init<
-      ConnectHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(ConnectHandler)(handler));
+    async_completion<ConnectHandler,
+      void (boost::system::error_code)> init(handler);
 
-    service_impl_.async_connect(impl, peer_endpoint, init.handler);
+    service_impl_.async_connect(impl, peer_endpoint, init.completion_handler);
 
     return init.result.get();
   }
 
   /// Set a socket option.
   template <typename SettableSocketOption>
-  boost::system::error_code set_option(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID set_option(implementation_type& impl,
       const SettableSocketOption& option, boost::system::error_code& ec)
   {
-    return service_impl_.set_option(impl, option, ec);
+    service_impl_.set_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get a socket option.
   template <typename GettableSocketOption>
-  boost::system::error_code get_option(const implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID get_option(const implementation_type& impl,
       GettableSocketOption& option, boost::system::error_code& ec) const
   {
-    return service_impl_.get_option(impl, option, ec);
+    service_impl_.get_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the socket.
   template <typename IoControlCommand>
-  boost::system::error_code io_control(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID io_control(implementation_type& impl,
       IoControlCommand& command, boost::system::error_code& ec)
   {
-    return service_impl_.io_control(impl, command, ec);
+    service_impl_.io_control(impl, command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the socket.
@@ -269,10 +273,11 @@ class datagram_socket_service
   }
 
   /// Sets the non-blocking mode of the socket.
-  boost::system::error_code non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.non_blocking(impl, mode, ec);
+    service_impl_.non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native socket implementation.
@@ -282,10 +287,11 @@ class datagram_socket_service
   }
 
   /// Sets the non-blocking mode of the native socket implementation.
-  boost::system::error_code native_non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.native_non_blocking(impl, mode, ec);
+    service_impl_.native_non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the local endpoint.
@@ -303,10 +309,36 @@ class datagram_socket_service
   }
 
   /// Disable sends or receives on the socket.
-  boost::system::error_code shutdown(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID shutdown(implementation_type& impl,
       socket_base::shutdown_type what, boost::system::error_code& ec)
   {
-    return service_impl_.shutdown(impl, what, ec);
+    service_impl_.shutdown(impl, what, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the socket to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  BOOST_ASIO_SYNC_OP_VOID wait(implementation_type& impl,
+      socket_base::wait_type w, boost::system::error_code& ec)
+  {
+    service_impl_.wait(impl, w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the socket to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(implementation_type& impl, socket_base::wait_type w,
+      BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    service_impl_.async_wait(impl, w, init.completion_handler);
+
+    return init.result.get();
   }
 
   /// Send the given data to the peer.
@@ -326,11 +358,10 @@ class datagram_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_send(impl, buffers, flags, init.handler);
+    service_impl_.async_send(impl, buffers, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -353,12 +384,11 @@ class datagram_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     service_impl_.async_send_to(impl, buffers,
-        destination, flags, init.handler);
+        destination, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -381,11 +411,10 @@ class datagram_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_receive(impl, buffers, flags, init.handler);
+    service_impl_.async_receive(impl, buffers, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -409,21 +438,20 @@ class datagram_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     service_impl_.async_receive_from(impl, buffers,
-        sender_endpoint, flags, init.handler);
+        sender_endpoint, flags, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -435,4 +463,6 @@ class datagram_socket_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_DATAGRAM_SOCKET_SERVICE_HPP
diff --git a/include/boost/asio/deadline_timer_service.hpp b/include/boost/asio/deadline_timer_service.hpp
index 26dcb42e4c..d109815188 100644
--- a/include/boost/asio/deadline_timer_service.hpp
+++ b/include/boost/asio/deadline_timer_service.hpp
@@ -17,15 +17,16 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME) \
   || defined(GENERATING_DOCUMENTATION)
 
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/deadline_timer_service.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/time_traits.hpp>
-#include <boost/asio/detail/timer_queue_ptime.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -37,7 +38,7 @@ template <typename TimeType,
     typename TimeTraits = boost::asio::time_traits<TimeType> >
 class deadline_timer_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<
       deadline_timer_service<TimeType, TimeTraits> >
@@ -46,7 +47,7 @@ class deadline_timer_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The time traits type.
@@ -70,11 +71,11 @@ class deadline_timer_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// Construct a new timer service for the specified io_service.
-  explicit deadline_timer_service(boost::asio::io_service& io_service)
+  /// Construct a new timer service for the specified io_context.
+  explicit deadline_timer_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        deadline_timer_service<TimeType, TimeTraits> >(io_service),
-      service_impl_(io_service)
+        deadline_timer_service<TimeType, TimeTraits> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -106,7 +107,7 @@ class deadline_timer_service
   /// Get the expiry time for the timer as an absolute time.
   time_type expires_at(const implementation_type& impl) const
   {
-    return service_impl_.expires_at(impl);
+    return service_impl_.expiry(impl);
   }
 
   /// Set the expiry time for the timer as an absolute time.
@@ -119,14 +120,14 @@ class deadline_timer_service
   /// Get the expiry time for the timer relative to now.
   duration_type expires_from_now(const implementation_type& impl) const
   {
-    return service_impl_.expires_from_now(impl);
+    return TimeTraits::subtract(service_impl_.expiry(impl), TimeTraits::now());
   }
 
   /// Set the expiry time for the timer relative to now.
   std::size_t expires_from_now(implementation_type& impl,
       const duration_type& expiry_time, boost::system::error_code& ec)
   {
-    return service_impl_.expires_from_now(impl, expiry_time, ec);
+    return service_impl_.expires_after(impl, expiry_time, ec);
   }
 
   // Perform a blocking wait on the timer.
@@ -142,20 +143,19 @@ class deadline_timer_service
   async_wait(implementation_type& impl,
       BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
   {
-    detail::async_result_init<
-      WaitHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
 
-    service_impl_.async_wait(impl, init.handler);
+    service_impl_.async_wait(impl, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -170,4 +170,6 @@ class deadline_timer_service
 #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
        // || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_DEADLINE_TIMER_SERVICE_HPP
diff --git a/include/boost/asio/defer.hpp b/include/boost/asio/defer.hpp
new file mode 100644
index 0000000000..966bfb4e14
--- /dev/null
+++ b/include/boost/asio/defer.hpp
@@ -0,0 +1,109 @@
+//
+// defer.hpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DEFER_HPP
+#define BOOST_ASIO_DEFER_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/execution_context.hpp>
+#include <boost/asio/is_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// Submits a completion token or function object for execution.
+/**
+ * This function submits an object for execution using the object's associated
+ * executor. The function object is queued for execution, and is never called
+ * from the current thread prior to returning from <tt>defer()</tt>.
+ *
+ * This function has the following effects:
+ *
+ * @li Constructs a function object handler of type @c Handler, initialized
+ * with <tt>handler(forward<CompletionToken>(token))</tt>.
+ *
+ * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
+ * initializing the object as <tt>result(handler)</tt>.
+ *
+ * @li Obtains the handler's associated executor object @c ex by performing
+ * <tt>get_associated_executor(handler)</tt>.
+ *
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * <tt>get_associated_allocator(handler)</tt>.
+ *
+ * @li Performs <tt>ex.defer(std::move(handler), alloc)</tt>.
+ *
+ * @li Returns <tt>result.get()</tt>.
+ */
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token);
+
+/// Submits a completion token or function object for execution.
+/**
+ * This function submits an object for execution using the specified executor.
+ * The function object is queued for execution, and is never called from the
+ * current thread prior to returning from <tt>defer()</tt>.
+ *
+ * This function has the following effects:
+ *
+ * @li Constructs a function object handler of type @c Handler, initialized
+ * with <tt>handler(forward<CompletionToken>(token))</tt>.
+ *
+ * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
+ * initializing the object as <tt>result(handler)</tt>.
+ *
+ * @li Obtains the handler's associated executor object @c ex1 by performing
+ * <tt>get_associated_executor(handler)</tt>.
+ *
+ * @li Creates a work object @c w by performing <tt>make_work(ex1)</tt>.
+ *
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * <tt>get_associated_allocator(handler)</tt>.
+ *
+ * @li Constructs a function object @c f with a function call operator that
+ * performs <tt>ex1.dispatch(std::move(handler), alloc)</tt> followed by
+ * <tt>w.reset()</tt>.
+ *
+ * @li Performs <tt>Executor(ex).defer(std::move(f), alloc)</tt>.
+ *
+ * @li Returns <tt>result.get()</tt>.
+ */
+template <typename Executor, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
+    const Executor& ex, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_executor<Executor>::value>::type* = 0);
+
+/// Submits a completion token or function object for execution.
+/**
+ * @returns <tt>defer(ctx.get_executor(), forward<CompletionToken>(token))</tt>.
+ */
+template <typename ExecutionContext, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
+    ExecutionContext& ctx, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type* = 0);
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/defer.hpp>
+
+#endif // BOOST_ASIO_DEFER_HPP
diff --git a/include/boost/asio/detail/addressof.hpp b/include/boost/asio/detail/addressof.hpp
deleted file mode 100644
index cc1099764d..0000000000
--- a/include/boost/asio/detail/addressof.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-//
-// detail/addressof.hpp
-// ~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_DETAIL_ADDRESSOF_HPP
-#define BOOST_ASIO_DETAIL_ADDRESSOF_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-
-#if defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
-# include <memory>
-#else // defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
-# include <boost/utility/addressof.hpp>
-#endif // defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
-
-namespace boost {
-namespace asio {
-namespace detail {
-
-#if defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
-using std::addressof;
-#else // defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
-using boost::addressof;
-#endif // defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
-
-} // namespace detail
-} // namespace asio
-} // namespace boost
-
-#endif // BOOST_ASIO_DETAIL_ADDRESSOF_HPP
diff --git a/include/boost/asio/detail/bind_handler.hpp b/include/boost/asio/detail/bind_handler.hpp
index 0f3672edab..cec413ccb1 100644
--- a/include/boost/asio/detail/bind_handler.hpp
+++ b/include/boost/asio/detail/bind_handler.hpp
@@ -16,9 +16,12 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_cont_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -30,8 +33,9 @@ template <typename Handler, typename Arg1>
 class binder1
 {
 public:
-  binder1(const Handler& handler, const Arg1& arg1)
-    : handler_(handler),
+  template <typename T>
+  binder1(int, BOOST_ASIO_MOVE_ARG(T) handler, const Arg1& arg1)
+    : handler_(BOOST_ASIO_MOVE_CAST(T)(handler)),
       arg1_(arg1)
   {
   }
@@ -42,6 +46,20 @@ class binder1
   {
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+  binder1(const binder1& other)
+    : handler_(other.handler_),
+      arg1_(other.arg1_)
+  {
+  }
+
+  binder1(binder1&& other)
+    : handler_(BOOST_ASIO_MOVE_CAST(Handler)(other.handler_)),
+      arg1_(BOOST_ASIO_MOVE_CAST(Arg1)(other.arg1_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
   void operator()()
   {
     handler_(static_cast<const Arg1&>(arg1_));
@@ -98,18 +116,21 @@ inline void asio_handler_invoke(const Function& function,
 }
 
 template <typename Handler, typename Arg1>
-inline binder1<Handler, Arg1> bind_handler(Handler handler,
-    const Arg1& arg1)
+inline binder1<typename decay<Handler>::type, Arg1> bind_handler(
+    BOOST_ASIO_MOVE_ARG(Handler) handler, const Arg1& arg1)
 {
-  return binder1<Handler, Arg1>(handler, arg1);
+  return binder1<typename decay<Handler>::type, Arg1>(0,
+      BOOST_ASIO_MOVE_CAST(Handler)(handler), arg1);
 }
 
 template <typename Handler, typename Arg1, typename Arg2>
 class binder2
 {
 public:
-  binder2(const Handler& handler, const Arg1& arg1, const Arg2& arg2)
-    : handler_(handler),
+  template <typename T>
+  binder2(int, BOOST_ASIO_MOVE_ARG(T) handler,
+      const Arg1& arg1, const Arg2& arg2)
+    : handler_(BOOST_ASIO_MOVE_CAST(T)(handler)),
       arg1_(arg1),
       arg2_(arg2)
   {
@@ -122,6 +143,22 @@ class binder2
   {
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+  binder2(const binder2& other)
+    : handler_(other.handler_),
+      arg1_(other.arg1_),
+      arg2_(other.arg2_)
+  {
+  }
+
+  binder2(binder2&& other)
+    : handler_(BOOST_ASIO_MOVE_CAST(Handler)(other.handler_)),
+      arg1_(BOOST_ASIO_MOVE_CAST(Arg1)(other.arg1_)),
+      arg2_(BOOST_ASIO_MOVE_CAST(Arg2)(other.arg2_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
   void operator()()
   {
     handler_(static_cast<const Arg1&>(arg1_),
@@ -180,309 +217,242 @@ inline void asio_handler_invoke(const Function& function,
 }
 
 template <typename Handler, typename Arg1, typename Arg2>
-inline binder2<Handler, Arg1, Arg2> bind_handler(Handler handler,
-    const Arg1& arg1, const Arg2& arg2)
+inline binder2<typename decay<Handler>::type, Arg1, Arg2> bind_handler(
+    BOOST_ASIO_MOVE_ARG(Handler) handler, const Arg1& arg1, const Arg2& arg2)
 {
-  return binder2<Handler, Arg1, Arg2>(handler, arg1, arg2);
+  return binder2<typename decay<Handler>::type, Arg1, Arg2>(0,
+      BOOST_ASIO_MOVE_CAST(Handler)(handler), arg1, arg2);
 }
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3>
-class binder3
+#if defined(BOOST_ASIO_HAS_MOVE)
+
+template <typename Handler, typename Arg1>
+class move_binder1
 {
 public:
-  binder3(const Handler& handler, const Arg1& arg1, const Arg2& arg2,
-      const Arg3& arg3)
-    : handler_(handler),
-      arg1_(arg1),
-      arg2_(arg2),
-      arg3_(arg3)
-  {
-  }
-
-  binder3(Handler& handler, const Arg1& arg1, const Arg2& arg2,
-      const Arg3& arg3)
+  move_binder1(int, BOOST_ASIO_MOVE_ARG(Handler) handler,
+      BOOST_ASIO_MOVE_ARG(Arg1) arg1)
     : handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
-      arg1_(arg1),
-      arg2_(arg2),
-      arg3_(arg3)
+      arg1_(BOOST_ASIO_MOVE_CAST(Arg1)(arg1))
   {
   }
 
-  void operator()()
+  move_binder1(move_binder1&& other)
+    : handler_(BOOST_ASIO_MOVE_CAST(Handler)(other.handler_)),
+      arg1_(BOOST_ASIO_MOVE_CAST(Arg1)(other.arg1_))
   {
-    handler_(static_cast<const Arg1&>(arg1_),
-        static_cast<const Arg2&>(arg2_),
-        static_cast<const Arg3&>(arg3_));
   }
 
-  void operator()() const
+  void operator()()
   {
-    handler_(arg1_, arg2_, arg3_);
+    handler_(BOOST_ASIO_MOVE_CAST(Arg1)(arg1_));
   }
 
 //private:
   Handler handler_;
   Arg1 arg1_;
-  Arg2 arg2_;
-  Arg3 arg3_;
 };
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3>
+template <typename Handler, typename Arg1>
 inline void* asio_handler_allocate(std::size_t size,
-    binder3<Handler, Arg1, Arg2, Arg3>* this_handler)
+    move_binder1<Handler, Arg1>* this_handler)
 {
   return boost_asio_handler_alloc_helpers::allocate(
       size, this_handler->handler_);
 }
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3>
+template <typename Handler, typename Arg1>
 inline void asio_handler_deallocate(void* pointer, std::size_t size,
-    binder3<Handler, Arg1, Arg2, Arg3>* this_handler)
+    move_binder1<Handler, Arg1>* this_handler)
 {
   boost_asio_handler_alloc_helpers::deallocate(
       pointer, size, this_handler->handler_);
 }
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3>
+template <typename Handler, typename Arg1>
 inline bool asio_handler_is_continuation(
-    binder3<Handler, Arg1, Arg2, Arg3>* this_handler)
+    move_binder1<Handler, Arg1>* this_handler)
 {
   return boost_asio_handler_cont_helpers::is_continuation(
       this_handler->handler_);
 }
 
-template <typename Function, typename Handler, typename Arg1, typename Arg2,
-    typename Arg3>
-inline void asio_handler_invoke(Function& function,
-    binder3<Handler, Arg1, Arg2, Arg3>* this_handler)
-{
-  boost_asio_handler_invoke_helpers::invoke(
-      function, this_handler->handler_);
-}
-
-template <typename Function, typename Handler, typename Arg1, typename Arg2,
-    typename Arg3>
-inline void asio_handler_invoke(const Function& function,
-    binder3<Handler, Arg1, Arg2, Arg3>* this_handler)
+template <typename Function, typename Handler, typename Arg1>
+inline void asio_handler_invoke(BOOST_ASIO_MOVE_ARG(Function) function,
+    move_binder1<Handler, Arg1>* this_handler)
 {
   boost_asio_handler_invoke_helpers::invoke(
-      function, this_handler->handler_);
-}
-
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3>
-inline binder3<Handler, Arg1, Arg2, Arg3> bind_handler(Handler handler,
-    const Arg1& arg1, const Arg2& arg2, const Arg3& arg3)
-{
-  return binder3<Handler, Arg1, Arg2, Arg3>(handler, arg1, arg2, arg3);
+      BOOST_ASIO_MOVE_CAST(Function)(function), this_handler->handler_);
 }
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4>
-class binder4
+template <typename Handler, typename Arg1, typename Arg2>
+class move_binder2
 {
 public:
-  binder4(const Handler& handler, const Arg1& arg1, const Arg2& arg2,
-      const Arg3& arg3, const Arg4& arg4)
-    : handler_(handler),
+  move_binder2(int, BOOST_ASIO_MOVE_ARG(Handler) handler,
+      const Arg1& arg1, BOOST_ASIO_MOVE_ARG(Arg2) arg2)
+    : handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
       arg1_(arg1),
-      arg2_(arg2),
-      arg3_(arg3),
-      arg4_(arg4)
+      arg2_(BOOST_ASIO_MOVE_CAST(Arg2)(arg2))
   {
   }
 
-  binder4(Handler& handler, const Arg1& arg1, const Arg2& arg2,
-      const Arg3& arg3, const Arg4& arg4)
-    : handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
-      arg1_(arg1),
-      arg2_(arg2),
-      arg3_(arg3),
-      arg4_(arg4)
+  move_binder2(move_binder2&& other)
+    : handler_(BOOST_ASIO_MOVE_CAST(Handler)(other.handler_)),
+      arg1_(BOOST_ASIO_MOVE_CAST(Arg1)(other.arg1_)),
+      arg2_(BOOST_ASIO_MOVE_CAST(Arg2)(other.arg2_))
   {
   }
 
   void operator()()
   {
     handler_(static_cast<const Arg1&>(arg1_),
-        static_cast<const Arg2&>(arg2_),
-        static_cast<const Arg3&>(arg3_),
-        static_cast<const Arg4&>(arg4_));
-  }
-
-  void operator()() const
-  {
-    handler_(arg1_, arg2_, arg3_, arg4_);
+        BOOST_ASIO_MOVE_CAST(Arg2)(arg2_));
   }
 
 //private:
   Handler handler_;
   Arg1 arg1_;
   Arg2 arg2_;
-  Arg3 arg3_;
-  Arg4 arg4_;
 };
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4>
+template <typename Handler, typename Arg1, typename Arg2>
 inline void* asio_handler_allocate(std::size_t size,
-    binder4<Handler, Arg1, Arg2, Arg3, Arg4>* this_handler)
+    move_binder2<Handler, Arg1, Arg2>* this_handler)
 {
   return boost_asio_handler_alloc_helpers::allocate(
       size, this_handler->handler_);
 }
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4>
+template <typename Handler, typename Arg1, typename Arg2>
 inline void asio_handler_deallocate(void* pointer, std::size_t size,
-    binder4<Handler, Arg1, Arg2, Arg3, Arg4>* this_handler)
+    move_binder2<Handler, Arg1, Arg2>* this_handler)
 {
   boost_asio_handler_alloc_helpers::deallocate(
       pointer, size, this_handler->handler_);
 }
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4>
+template <typename Handler, typename Arg1, typename Arg2>
 inline bool asio_handler_is_continuation(
-    binder4<Handler, Arg1, Arg2, Arg3, Arg4>* this_handler)
+    move_binder2<Handler, Arg1, Arg2>* this_handler)
 {
   return boost_asio_handler_cont_helpers::is_continuation(
       this_handler->handler_);
 }
 
-template <typename Function, typename Handler, typename Arg1, typename Arg2,
-    typename Arg3, typename Arg4>
-inline void asio_handler_invoke(Function& function,
-    binder4<Handler, Arg1, Arg2, Arg3, Arg4>* this_handler)
+template <typename Function, typename Handler, typename Arg1, typename Arg2>
+inline void asio_handler_invoke(BOOST_ASIO_MOVE_ARG(Function) function,
+    move_binder2<Handler, Arg1, Arg2>* this_handler)
 {
   boost_asio_handler_invoke_helpers::invoke(
-      function, this_handler->handler_);
+      BOOST_ASIO_MOVE_CAST(Function)(function), this_handler->handler_);
 }
 
-template <typename Function, typename Handler, typename Arg1, typename Arg2,
-    typename Arg3, typename Arg4>
-inline void asio_handler_invoke(const Function& function,
-    binder4<Handler, Arg1, Arg2, Arg3, Arg4>* this_handler)
-{
-  boost_asio_handler_invoke_helpers::invoke(
-      function, this_handler->handler_);
-}
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4>
-inline binder4<Handler, Arg1, Arg2, Arg3, Arg4> bind_handler(
-    Handler handler, const Arg1& arg1, const Arg2& arg2,
-    const Arg3& arg3, const Arg4& arg4)
-{
-  return binder4<Handler, Arg1, Arg2, Arg3, Arg4>(handler, arg1, arg2, arg3,
-      arg4);
-}
+} // namespace detail
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4, typename Arg5>
-class binder5
+template <typename Handler, typename Arg1, typename Allocator>
+struct associated_allocator<detail::binder1<Handler, Arg1>, Allocator>
 {
-public:
-  binder5(const Handler& handler, const Arg1& arg1, const Arg2& arg2,
-      const Arg3& arg3, const Arg4& arg4, const Arg5& arg5)
-    : handler_(handler),
-      arg1_(arg1),
-      arg2_(arg2),
-      arg3_(arg3),
-      arg4_(arg4),
-      arg5_(arg5)
+  typedef typename associated_allocator<Handler, Allocator>::type type;
+
+  static type get(const detail::binder1<Handler, Arg1>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
   {
+    return associated_allocator<Handler, Allocator>::get(h.handler_, a);
   }
+};
 
-  binder5(Handler& handler, const Arg1& arg1, const Arg2& arg2,
-      const Arg3& arg3, const Arg4& arg4, const Arg5& arg5)
-    : handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
-      arg1_(arg1),
-      arg2_(arg2),
-      arg3_(arg3),
-      arg4_(arg4),
-      arg5_(arg5)
+template <typename Handler, typename Arg1, typename Arg2, typename Allocator>
+struct associated_allocator<detail::binder2<Handler, Arg1, Arg2>, Allocator>
+{
+  typedef typename associated_allocator<Handler, Allocator>::type type;
+
+  static type get(const detail::binder2<Handler, Arg1, Arg2>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
   {
+    return associated_allocator<Handler, Allocator>::get(h.handler_, a);
   }
+};
 
-  void operator()()
+template <typename Handler, typename Arg1, typename Executor>
+struct associated_executor<detail::binder1<Handler, Arg1>, Executor>
+{
+  typedef typename associated_executor<Handler, Executor>::type type;
+
+  static type get(const detail::binder1<Handler, Arg1>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
   {
-    handler_(static_cast<const Arg1&>(arg1_),
-        static_cast<const Arg2&>(arg2_),
-        static_cast<const Arg3&>(arg3_),
-        static_cast<const Arg4&>(arg4_),
-        static_cast<const Arg5&>(arg5_));
+    return associated_executor<Handler, Executor>::get(h.handler_, ex);
   }
+};
 
-  void operator()() const
+template <typename Handler, typename Arg1, typename Arg2, typename Executor>
+struct associated_executor<detail::binder2<Handler, Arg1, Arg2>, Executor>
+{
+  typedef typename associated_executor<Handler, Executor>::type type;
+
+  static type get(const detail::binder2<Handler, Arg1, Arg2>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
   {
-    handler_(arg1_, arg2_, arg3_, arg4_, arg5_);
+    return associated_executor<Handler, Executor>::get(h.handler_, ex);
   }
-
-//private:
-  Handler handler_;
-  Arg1 arg1_;
-  Arg2 arg2_;
-  Arg3 arg3_;
-  Arg4 arg4_;
-  Arg5 arg5_;
 };
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4, typename Arg5>
-inline void* asio_handler_allocate(std::size_t size,
-    binder5<Handler, Arg1, Arg2, Arg3, Arg4, Arg5>* this_handler)
-{
-  return boost_asio_handler_alloc_helpers::allocate(
-      size, this_handler->handler_);
-}
+#if defined(BOOST_ASIO_HAS_MOVE)
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4, typename Arg5>
-inline void asio_handler_deallocate(void* pointer, std::size_t size,
-    binder5<Handler, Arg1, Arg2, Arg3, Arg4, Arg5>* this_handler)
+template <typename Handler, typename Arg1, typename Allocator>
+struct associated_allocator<detail::move_binder1<Handler, Arg1>, Allocator>
 {
-  boost_asio_handler_alloc_helpers::deallocate(
-      pointer, size, this_handler->handler_);
-}
+  typedef typename associated_allocator<Handler, Allocator>::type type;
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4, typename Arg5>
-inline bool asio_handler_is_continuation(
-    binder5<Handler, Arg1, Arg2, Arg3, Arg4, Arg5>* this_handler)
-{
-  return boost_asio_handler_cont_helpers::is_continuation(
-      this_handler->handler_);
-}
+  static type get(const detail::move_binder1<Handler, Arg1>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<Handler, Allocator>::get(h.handler_, a);
+  }
+};
 
-template <typename Function, typename Handler, typename Arg1, typename Arg2,
-    typename Arg3, typename Arg4, typename Arg5>
-inline void asio_handler_invoke(Function& function,
-    binder5<Handler, Arg1, Arg2, Arg3, Arg4, Arg5>* this_handler)
+template <typename Handler, typename Arg1, typename Arg2, typename Allocator>
+struct associated_allocator<
+    detail::move_binder2<Handler, Arg1, Arg2>, Allocator>
 {
-  boost_asio_handler_invoke_helpers::invoke(
-      function, this_handler->handler_);
-}
+  typedef typename associated_allocator<Handler, Allocator>::type type;
 
-template <typename Function, typename Handler, typename Arg1, typename Arg2,
-    typename Arg3, typename Arg4, typename Arg5>
-inline void asio_handler_invoke(const Function& function,
-    binder5<Handler, Arg1, Arg2, Arg3, Arg4, Arg5>* this_handler)
+  static type get(const detail::move_binder2<Handler, Arg1, Arg2>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<Handler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename Handler, typename Arg1, typename Executor>
+struct associated_executor<detail::move_binder1<Handler, Arg1>, Executor>
 {
-  boost_asio_handler_invoke_helpers::invoke(
-      function, this_handler->handler_);
-}
+  typedef typename associated_executor<Handler, Executor>::type type;
+
+  static type get(const detail::move_binder1<Handler, Arg1>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<Handler, Executor>::get(h.handler_, ex);
+  }
+};
 
-template <typename Handler, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4, typename Arg5>
-inline binder5<Handler, Arg1, Arg2, Arg3, Arg4, Arg5> bind_handler(
-    Handler handler, const Arg1& arg1, const Arg2& arg2,
-    const Arg3& arg3, const Arg4& arg4, const Arg5& arg5)
+template <typename Handler, typename Arg1, typename Arg2, typename Executor>
+struct associated_executor<detail::move_binder2<Handler, Arg1, Arg2>, Executor>
 {
-  return binder5<Handler, Arg1, Arg2, Arg3, Arg4, Arg5>(handler, arg1, arg2,
-      arg3, arg4, arg5);
-}
+  typedef typename associated_executor<Handler, Executor>::type type;
+
+  static type get(const detail::move_binder2<Handler, Arg1, Arg2>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<Handler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
-} // namespace detail
 } // namespace asio
 } // namespace boost
 
diff --git a/include/boost/asio/detail/buffer_sequence_adapter.hpp b/include/boost/asio/detail/buffer_sequence_adapter.hpp
index 20c529e0a2..e04b292266 100644
--- a/include/boost/asio/detail/buffer_sequence_adapter.hpp
+++ b/include/boost/asio/detail/buffer_sequence_adapter.hpp
@@ -28,11 +28,12 @@ namespace detail {
 
 class buffer_sequence_adapter_base
 {
-protected:
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+public:
   // The maximum number of buffers to support in a single operation.
   enum { max_buffers = 1 };
 
+protected:
   typedef Windows::Storage::Streams::IBuffer^ native_buffer_type;
 
   BOOST_ASIO_DECL static void init_native_buffer(
@@ -43,28 +44,32 @@ class buffer_sequence_adapter_base
       native_buffer_type& buf,
       const boost::asio::const_buffer& buffer);
 #elif defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
+public:
   // The maximum number of buffers to support in a single operation.
   enum { max_buffers = 64 < max_iov_len ? 64 : max_iov_len };
 
+protected:
   typedef WSABUF native_buffer_type;
 
   static void init_native_buffer(WSABUF& buf,
       const boost::asio::mutable_buffer& buffer)
   {
-    buf.buf = boost::asio::buffer_cast<char*>(buffer);
-    buf.len = static_cast<ULONG>(boost::asio::buffer_size(buffer));
+    buf.buf = static_cast<char*>(buffer.data());
+    buf.len = static_cast<ULONG>(buffer.size());
   }
 
   static void init_native_buffer(WSABUF& buf,
       const boost::asio::const_buffer& buffer)
   {
-    buf.buf = const_cast<char*>(boost::asio::buffer_cast<const char*>(buffer));
-    buf.len = static_cast<ULONG>(boost::asio::buffer_size(buffer));
+    buf.buf = const_cast<char*>(static_cast<const char*>(buffer.data()));
+    buf.len = static_cast<ULONG>(buffer.size());
   }
 #else // defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
+public:
   // The maximum number of buffers to support in a single operation.
   enum { max_buffers = 64 < max_iov_len ? 64 : max_iov_len };
 
+protected:
   typedef iovec native_buffer_type;
 
   static void init_iov_base(void*& base, void* addr)
@@ -81,16 +86,15 @@ class buffer_sequence_adapter_base
   static void init_native_buffer(iovec& iov,
       const boost::asio::mutable_buffer& buffer)
   {
-    init_iov_base(iov.iov_base, boost::asio::buffer_cast<void*>(buffer));
-    iov.iov_len = boost::asio::buffer_size(buffer);
+    init_iov_base(iov.iov_base, buffer.data());
+    iov.iov_len = buffer.size();
   }
 
   static void init_native_buffer(iovec& iov,
       const boost::asio::const_buffer& buffer)
   {
-    init_iov_base(iov.iov_base, const_cast<void*>(
-          boost::asio::buffer_cast<const void*>(buffer)));
-    iov.iov_len = boost::asio::buffer_size(buffer);
+    init_iov_base(iov.iov_base, const_cast<void*>(buffer.data()));
+    iov.iov_len = buffer.size();
   }
 #endif // defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
 };
@@ -104,14 +108,9 @@ class buffer_sequence_adapter
   explicit buffer_sequence_adapter(const Buffers& buffer_sequence)
     : count_(0), total_buffer_size_(0)
   {
-    typename Buffers::const_iterator iter = buffer_sequence.begin();
-    typename Buffers::const_iterator end = buffer_sequence.end();
-    for (; iter != end && count_ < max_buffers; ++iter, ++count_)
-    {
-      Buffer buffer(*iter);
-      init_native_buffer(buffers_[count_], buffer);
-      total_buffer_size_ += boost::asio::buffer_size(buffer);
-    }
+    buffer_sequence_adapter::init(
+        boost::asio::buffer_sequence_begin(buffer_sequence),
+        boost::asio::buffer_sequence_end(buffer_sequence));
   }
 
   native_buffer_type* buffers()
@@ -124,6 +123,11 @@ class buffer_sequence_adapter
     return count_;
   }
 
+  std::size_t total_size() const
+  {
+    return total_buffer_size_;
+  }
+
   bool all_empty() const
   {
     return total_buffer_size_ == 0;
@@ -131,45 +135,184 @@ class buffer_sequence_adapter
 
   static bool all_empty(const Buffers& buffer_sequence)
   {
-    typename Buffers::const_iterator iter = buffer_sequence.begin();
-    typename Buffers::const_iterator end = buffer_sequence.end();
+    return buffer_sequence_adapter::all_empty(
+        boost::asio::buffer_sequence_begin(buffer_sequence),
+        boost::asio::buffer_sequence_end(buffer_sequence));
+  }
+
+  static void validate(const Buffers& buffer_sequence)
+  {
+    buffer_sequence_adapter::validate(
+        boost::asio::buffer_sequence_begin(buffer_sequence),
+        boost::asio::buffer_sequence_end(buffer_sequence));
+  }
+
+  static Buffer first(const Buffers& buffer_sequence)
+  {
+    return buffer_sequence_adapter::first(
+        boost::asio::buffer_sequence_begin(buffer_sequence),
+        boost::asio::buffer_sequence_end(buffer_sequence));
+  }
+
+private:
+  template <typename Iterator>
+  void init(Iterator begin, Iterator end)
+  {
+    Iterator iter = begin;
+    for (; iter != end && count_ < max_buffers; ++iter, ++count_)
+    {
+      Buffer buffer(*iter);
+      init_native_buffer(buffers_[count_], buffer);
+      total_buffer_size_ += buffer.size();
+    }
+  }
+
+  template <typename Iterator>
+  static bool all_empty(Iterator begin, Iterator end)
+  {
+    Iterator iter = begin;
     std::size_t i = 0;
     for (; iter != end && i < max_buffers; ++iter, ++i)
-      if (boost::asio::buffer_size(Buffer(*iter)) > 0)
+      if (Buffer(*iter).size() > 0)
         return false;
     return true;
   }
 
-  static void validate(const Buffers& buffer_sequence)
+  template <typename Iterator>
+  static void validate(Iterator begin, Iterator end)
   {
-    typename Buffers::const_iterator iter = buffer_sequence.begin();
-    typename Buffers::const_iterator end = buffer_sequence.end();
+    Iterator iter = begin;
     for (; iter != end; ++iter)
     {
       Buffer buffer(*iter);
-      boost::asio::buffer_cast<const void*>(buffer);
+      buffer.data();
     }
   }
 
-  static Buffer first(const Buffers& buffer_sequence)
+  template <typename Iterator>
+  static Buffer first(Iterator begin, Iterator end)
   {
-    typename Buffers::const_iterator iter = buffer_sequence.begin();
-    typename Buffers::const_iterator end = buffer_sequence.end();
+    Iterator iter = begin;
     for (; iter != end; ++iter)
     {
       Buffer buffer(*iter);
-      if (boost::asio::buffer_size(buffer) != 0)
+      if (buffer.size() != 0)
         return buffer;
     }
     return Buffer();
   }
 
-private:
   native_buffer_type buffers_[max_buffers];
   std::size_t count_;
   std::size_t total_buffer_size_;
 };
 
+template <typename Buffer>
+class buffer_sequence_adapter<Buffer, boost::asio::mutable_buffer>
+  : buffer_sequence_adapter_base
+{
+public:
+  explicit buffer_sequence_adapter(
+      const boost::asio::mutable_buffer& buffer_sequence)
+  {
+    init_native_buffer(buffer_, Buffer(buffer_sequence));
+    total_buffer_size_ = buffer_sequence.size();
+  }
+
+  native_buffer_type* buffers()
+  {
+    return &buffer_;
+  }
+
+  std::size_t count() const
+  {
+    return 1;
+  }
+
+  std::size_t total_size() const
+  {
+    return total_buffer_size_;
+  }
+
+  bool all_empty() const
+  {
+    return total_buffer_size_ == 0;
+  }
+
+  static bool all_empty(const boost::asio::mutable_buffer& buffer_sequence)
+  {
+    return buffer_sequence.size() == 0;
+  }
+
+  static void validate(const boost::asio::mutable_buffer& buffer_sequence)
+  {
+    buffer_sequence.data();
+  }
+
+  static Buffer first(const boost::asio::mutable_buffer& buffer_sequence)
+  {
+    return Buffer(buffer_sequence);
+  }
+
+private:
+  native_buffer_type buffer_;
+  std::size_t total_buffer_size_;
+};
+
+template <typename Buffer>
+class buffer_sequence_adapter<Buffer, boost::asio::const_buffer>
+  : buffer_sequence_adapter_base
+{
+public:
+  explicit buffer_sequence_adapter(
+      const boost::asio::const_buffer& buffer_sequence)
+  {
+    init_native_buffer(buffer_, Buffer(buffer_sequence));
+    total_buffer_size_ = buffer_sequence.size();
+  }
+
+  native_buffer_type* buffers()
+  {
+    return &buffer_;
+  }
+
+  std::size_t count() const
+  {
+    return 1;
+  }
+
+  std::size_t total_size() const
+  {
+    return total_buffer_size_;
+  }
+
+  bool all_empty() const
+  {
+    return total_buffer_size_ == 0;
+  }
+
+  static bool all_empty(const boost::asio::const_buffer& buffer_sequence)
+  {
+    return buffer_sequence.size() == 0;
+  }
+
+  static void validate(const boost::asio::const_buffer& buffer_sequence)
+  {
+    buffer_sequence.data();
+  }
+
+  static Buffer first(const boost::asio::const_buffer& buffer_sequence)
+  {
+    return Buffer(buffer_sequence);
+  }
+
+private:
+  native_buffer_type buffer_;
+  std::size_t total_buffer_size_;
+};
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
 template <typename Buffer>
 class buffer_sequence_adapter<Buffer, boost::asio::mutable_buffers_1>
   : buffer_sequence_adapter_base
@@ -179,7 +322,7 @@ class buffer_sequence_adapter<Buffer, boost::asio::mutable_buffers_1>
       const boost::asio::mutable_buffers_1& buffer_sequence)
   {
     init_native_buffer(buffer_, Buffer(buffer_sequence));
-    total_buffer_size_ = boost::asio::buffer_size(buffer_sequence);
+    total_buffer_size_ = buffer_sequence.size();
   }
 
   native_buffer_type* buffers()
@@ -192,6 +335,11 @@ class buffer_sequence_adapter<Buffer, boost::asio::mutable_buffers_1>
     return 1;
   }
 
+  std::size_t total_size() const
+  {
+    return total_buffer_size_;
+  }
+
   bool all_empty() const
   {
     return total_buffer_size_ == 0;
@@ -199,12 +347,12 @@ class buffer_sequence_adapter<Buffer, boost::asio::mutable_buffers_1>
 
   static bool all_empty(const boost::asio::mutable_buffers_1& buffer_sequence)
   {
-    return boost::asio::buffer_size(buffer_sequence) == 0;
+    return buffer_sequence.size() == 0;
   }
 
   static void validate(const boost::asio::mutable_buffers_1& buffer_sequence)
   {
-    boost::asio::buffer_cast<const void*>(buffer_sequence);
+    buffer_sequence.data();
   }
 
   static Buffer first(const boost::asio::mutable_buffers_1& buffer_sequence)
@@ -226,7 +374,7 @@ class buffer_sequence_adapter<Buffer, boost::asio::const_buffers_1>
       const boost::asio::const_buffers_1& buffer_sequence)
   {
     init_native_buffer(buffer_, Buffer(buffer_sequence));
-    total_buffer_size_ = boost::asio::buffer_size(buffer_sequence);
+    total_buffer_size_ = buffer_sequence.size();
   }
 
   native_buffer_type* buffers()
@@ -239,6 +387,11 @@ class buffer_sequence_adapter<Buffer, boost::asio::const_buffers_1>
     return 1;
   }
 
+  std::size_t total_size() const
+  {
+    return total_buffer_size_;
+  }
+
   bool all_empty() const
   {
     return total_buffer_size_ == 0;
@@ -246,12 +399,12 @@ class buffer_sequence_adapter<Buffer, boost::asio::const_buffers_1>
 
   static bool all_empty(const boost::asio::const_buffers_1& buffer_sequence)
   {
-    return boost::asio::buffer_size(buffer_sequence) == 0;
+    return buffer_sequence.size() == 0;
   }
 
   static void validate(const boost::asio::const_buffers_1& buffer_sequence)
   {
-    boost::asio::buffer_cast<const void*>(buffer_sequence);
+    buffer_sequence.data();
   }
 
   static Buffer first(const boost::asio::const_buffers_1& buffer_sequence)
@@ -264,6 +417,8 @@ class buffer_sequence_adapter<Buffer, boost::asio::const_buffers_1>
   std::size_t total_buffer_size_;
 };
 
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
 template <typename Buffer, typename Elem>
 class buffer_sequence_adapter<Buffer, boost::array<Elem, 2> >
   : buffer_sequence_adapter_base
@@ -274,8 +429,7 @@ class buffer_sequence_adapter<Buffer, boost::array<Elem, 2> >
   {
     init_native_buffer(buffers_[0], Buffer(buffer_sequence[0]));
     init_native_buffer(buffers_[1], Buffer(buffer_sequence[1]));
-    total_buffer_size_ = boost::asio::buffer_size(buffer_sequence[0])
-      + boost::asio::buffer_size(buffer_sequence[1]);
+    total_buffer_size_ = buffer_sequence[0].size() + buffer_sequence[1].size();
   }
 
   native_buffer_type* buffers()
@@ -288,6 +442,11 @@ class buffer_sequence_adapter<Buffer, boost::array<Elem, 2> >
     return 2;
   }
 
+  std::size_t total_size() const
+  {
+    return total_buffer_size_;
+  }
+
   bool all_empty() const
   {
     return total_buffer_size_ == 0;
@@ -295,19 +454,18 @@ class buffer_sequence_adapter<Buffer, boost::array<Elem, 2> >
 
   static bool all_empty(const boost::array<Elem, 2>& buffer_sequence)
   {
-    return boost::asio::buffer_size(buffer_sequence[0]) == 0
-      && boost::asio::buffer_size(buffer_sequence[1]) == 0;
+    return buffer_sequence[0].size() == 0 && buffer_sequence[1].size() == 0;
   }
 
   static void validate(const boost::array<Elem, 2>& buffer_sequence)
   {
-    boost::asio::buffer_cast<const void*>(buffer_sequence[0]);
-    boost::asio::buffer_cast<const void*>(buffer_sequence[1]);
+    buffer_sequence[0].data();
+    buffer_sequence[1].data();
   }
 
   static Buffer first(const boost::array<Elem, 2>& buffer_sequence)
   {
-    return Buffer(boost::asio::buffer_size(buffer_sequence[0]) != 0
+    return Buffer(buffer_sequence[0].size() != 0
         ? buffer_sequence[0] : buffer_sequence[1]);
   }
 
@@ -328,8 +486,7 @@ class buffer_sequence_adapter<Buffer, std::array<Elem, 2> >
   {
     init_native_buffer(buffers_[0], Buffer(buffer_sequence[0]));
     init_native_buffer(buffers_[1], Buffer(buffer_sequence[1]));
-    total_buffer_size_ = boost::asio::buffer_size(buffer_sequence[0])
-      + boost::asio::buffer_size(buffer_sequence[1]);
+    total_buffer_size_ = buffer_sequence[0].size() + buffer_sequence[1].size();
   }
 
   native_buffer_type* buffers()
@@ -342,6 +499,11 @@ class buffer_sequence_adapter<Buffer, std::array<Elem, 2> >
     return 2;
   }
 
+  std::size_t total_size() const
+  {
+    return total_buffer_size_;
+  }
+
   bool all_empty() const
   {
     return total_buffer_size_ == 0;
@@ -349,19 +511,18 @@ class buffer_sequence_adapter<Buffer, std::array<Elem, 2> >
 
   static bool all_empty(const std::array<Elem, 2>& buffer_sequence)
   {
-    return boost::asio::buffer_size(buffer_sequence[0]) == 0
-      && boost::asio::buffer_size(buffer_sequence[1]) == 0;
+    return buffer_sequence[0].size() == 0 && buffer_sequence[1].size() == 0;
   }
 
   static void validate(const std::array<Elem, 2>& buffer_sequence)
   {
-    boost::asio::buffer_cast<const void*>(buffer_sequence[0]);
-    boost::asio::buffer_cast<const void*>(buffer_sequence[1]);
+    buffer_sequence[0].data();
+    buffer_sequence[1].data();
   }
 
   static Buffer first(const std::array<Elem, 2>& buffer_sequence)
   {
-    return Buffer(boost::asio::buffer_size(buffer_sequence[0]) != 0
+    return Buffer(buffer_sequence[0].size() != 0
         ? buffer_sequence[0] : buffer_sequence[1]);
   }
 
diff --git a/include/boost/asio/detail/call_stack.hpp b/include/boost/asio/detail/call_stack.hpp
index 5253e3b153..52de6ef00d 100644
--- a/include/boost/asio/detail/call_stack.hpp
+++ b/include/boost/asio/detail/call_stack.hpp
@@ -26,7 +26,7 @@ namespace asio {
 namespace detail {
 
 // Helper class to determine whether or not the current thread is inside an
-// invocation of io_service::run() for a specified io_service object.
+// invocation of io_context::run() for a specified io_context object.
 template <typename Key, typename Value = unsigned char>
 class call_stack
 {
diff --git a/include/boost/asio/detail/chrono.hpp b/include/boost/asio/detail/chrono.hpp
new file mode 100644
index 0000000000..923e7697b2
--- /dev/null
+++ b/include/boost/asio/detail/chrono.hpp
@@ -0,0 +1,68 @@
+//
+// detail/chrono.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_CHRONO_HPP
+#define BOOST_ASIO_DETAIL_CHRONO_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_STD_CHRONO)
+# include <chrono>
+#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
+# include <boost/chrono/system_clocks.hpp>
+#endif // defined(BOOST_ASIO_HAS_BOOST_CHRONO)
+
+namespace boost {
+namespace asio {
+namespace chrono {
+
+#if defined(BOOST_ASIO_HAS_STD_CHRONO)
+using std::chrono::duration;
+using std::chrono::time_point;
+using std::chrono::duration_cast;
+using std::chrono::nanoseconds;
+using std::chrono::microseconds;
+using std::chrono::milliseconds;
+using std::chrono::seconds;
+using std::chrono::minutes;
+using std::chrono::hours;
+using std::chrono::time_point_cast;
+#if defined(BOOST_ASIO_HAS_STD_CHRONO_MONOTONIC_CLOCK)
+typedef std::chrono::monotonic_clock steady_clock;
+#else // defined(BOOST_ASIO_HAS_STD_CHRONO_MONOTONIC_CLOCK)
+using std::chrono::steady_clock;
+#endif // defined(BOOST_ASIO_HAS_STD_CHRONO_MONOTONIC_CLOCK)
+using std::chrono::system_clock;
+using std::chrono::high_resolution_clock;
+#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
+using boost::chrono::duration;
+using boost::chrono::time_point;
+using boost::chrono::duration_cast;
+using boost::chrono::nanoseconds;
+using boost::chrono::microseconds;
+using boost::chrono::milliseconds;
+using boost::chrono::seconds;
+using boost::chrono::minutes;
+using boost::chrono::hours;
+using boost::chrono::time_point_cast;
+using boost::chrono::system_clock;
+using boost::chrono::steady_clock;
+using boost::chrono::high_resolution_clock;
+#endif // defined(BOOST_ASIO_HAS_BOOST_CHRONO)
+
+} // namespace chrono
+} // namespace asio
+} // namespace boost
+
+#endif // BOOST_ASIO_DETAIL_CHRONO_HPP
diff --git a/include/boost/asio/detail/completion_handler.hpp b/include/boost/asio/detail/completion_handler.hpp
index 6333dce569..d18d372eeb 100644
--- a/include/boost/asio/detail/completion_handler.hpp
+++ b/include/boost/asio/detail/completion_handler.hpp
@@ -15,11 +15,11 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/config.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
-#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/handler_work.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -38,17 +38,19 @@ class completion_handler : public operation
     : operation(&completion_handler::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(h))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     completion_handler* h(static_cast<completion_handler*>(base));
     ptr p = { boost::asio::detail::addressof(h->handler_), h, h };
+    handler_work<Handler> w(h->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((h));
+    BOOST_ASIO_HANDLER_COMPLETION((*h));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -65,7 +67,7 @@ class completion_handler : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN(());
-      boost_asio_handler_invoke_helpers::invoke(handler, handler);
+      w.complete(handler, handler);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/concurrency_hint.hpp b/include/boost/asio/detail/concurrency_hint.hpp
new file mode 100644
index 0000000000..0a13205499
--- /dev/null
+++ b/include/boost/asio/detail/concurrency_hint.hpp
@@ -0,0 +1,94 @@
+//
+// detail/concurrency_hint.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_CONCURRENCY_HINT_HPP
+#define BOOST_ASIO_DETAIL_CONCURRENCY_HINT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+
+// The concurrency hint ID and mask are used to identify when a "well-known"
+// concurrency hint value has been passed to the io_context.
+#define BOOST_ASIO_CONCURRENCY_HINT_ID 0xA5100000u
+#define BOOST_ASIO_CONCURRENCY_HINT_ID_MASK 0xFFFF0000u
+
+// If set, this bit indicates that the scheduler should perform locking.
+#define BOOST_ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER 0x1u
+
+// If set, this bit indicates that the reactor should perform locking when
+// managing descriptor registrations.
+#define BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION 0x2u
+
+// If set, this bit indicates that the reactor should perform locking for I/O.
+#define BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_IO 0x4u
+
+// Helper macro to determine if we have a special concurrency hint.
+#define BOOST_ASIO_CONCURRENCY_HINT_IS_SPECIAL(hint) \
+  ((static_cast<unsigned>(hint) \
+    & BOOST_ASIO_CONCURRENCY_HINT_ID_MASK) \
+      == BOOST_ASIO_CONCURRENCY_HINT_ID)
+
+// Helper macro to determine if locking is enabled for a given facility.
+#define BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(facility, hint) \
+  (((static_cast<unsigned>(hint) \
+    & (BOOST_ASIO_CONCURRENCY_HINT_ID_MASK \
+      | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_ ## facility)) \
+        ^ BOOST_ASIO_CONCURRENCY_HINT_ID) != 0)
+
+// This special concurrency hint disables locking in both the scheduler and
+// reactor I/O. This hint has the following restrictions:
+//
+// - Care must be taken to ensure that all operations on the io_context and any
+//   of its associated I/O objects (such as sockets and timers) occur in only
+//   one thread at a time.
+//
+// - Asynchronous resolve operations fail with operation_not_supported.
+//
+// - If a signal_set is used with the io_context, signal_set objects cannot be
+//   used with any other io_context in the program.
+#define BOOST_ASIO_CONCURRENCY_HINT_UNSAFE \
+  static_cast<int>(BOOST_ASIO_CONCURRENCY_HINT_ID)
+
+// This special concurrency hint disables locking in the reactor I/O. This hint
+// has the following restrictions:
+//
+// - Care must be taken to ensure that run functions on the io_context, and all
+//   operations on the io_context's associated I/O objects (such as sockets and
+//   timers), occur in only one thread at a time.
+#define BOOST_ASIO_CONCURRENCY_HINT_UNSAFE_IO \
+  static_cast<int>(BOOST_ASIO_CONCURRENCY_HINT_ID \
+      | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER \
+      | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION)
+
+// The special concurrency hint provides full thread safety.
+#define BOOST_ASIO_CONCURRENCY_HINT_SAFE \
+  static_cast<int>(BOOST_ASIO_CONCURRENCY_HINT_ID \
+      | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_SCHEDULER \
+      | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_REGISTRATION \
+      | BOOST_ASIO_CONCURRENCY_HINT_LOCKING_REACTOR_IO)
+
+// This #define may be overridden at compile time to specify a program-wide
+// default concurrency hint, used by the zero-argument io_context constructor.
+#if !defined(BOOST_ASIO_CONCURRENCY_HINT_DEFAULT)
+# define BOOST_ASIO_CONCURRENCY_HINT_DEFAULT -1
+#endif // !defined(BOOST_ASIO_CONCURRENCY_HINT_DEFAULT)
+
+// This #define may be overridden at compile time to specify a program-wide
+// concurrency hint, used by the one-argument io_context constructor when
+// passed a value of 1.
+#if !defined(BOOST_ASIO_CONCURRENCY_HINT_1)
+# define BOOST_ASIO_CONCURRENCY_HINT_1 1
+#endif // !defined(BOOST_ASIO_CONCURRENCY_HINT_DEFAULT)
+
+#endif // BOOST_ASIO_DETAIL_CONCURRENCY_HINT_HPP
diff --git a/include/boost/asio/detail/conditionally_enabled_event.hpp b/include/boost/asio/detail/conditionally_enabled_event.hpp
new file mode 100644
index 0000000000..c2be28587c
--- /dev/null
+++ b/include/boost/asio/detail/conditionally_enabled_event.hpp
@@ -0,0 +1,114 @@
+//
+// detail/conditionally_enabled_event.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
+#define BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/conditionally_enabled_mutex.hpp>
+#include <boost/asio/detail/event.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/null_event.hpp>
+#include <boost/asio/detail/scoped_lock.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+// Mutex adapter used to conditionally enable or disable locking.
+class conditionally_enabled_event
+  : private noncopyable
+{
+public:
+  // Constructor.
+  conditionally_enabled_event()
+  {
+  }
+
+  // Destructor.
+  ~conditionally_enabled_event()
+  {
+  }
+
+  // Signal the event. (Retained for backward compatibility.)
+  void signal(conditionally_enabled_mutex::scoped_lock& lock)
+  {
+    if (lock.mutex_.enabled_)
+      event_.signal(lock);
+  }
+
+  // Signal all waiters.
+  void signal_all(conditionally_enabled_mutex::scoped_lock& lock)
+  {
+    if (lock.mutex_.enabled_)
+      event_.signal_all(lock);
+  }
+
+  // Unlock the mutex and signal one waiter.
+  void unlock_and_signal_one(
+      conditionally_enabled_mutex::scoped_lock& lock)
+  {
+    if (lock.mutex_.enabled_)
+      event_.unlock_and_signal_one(lock);
+  }
+
+  // If there's a waiter, unlock the mutex and signal it.
+  bool maybe_unlock_and_signal_one(
+      conditionally_enabled_mutex::scoped_lock& lock)
+  {
+    if (lock.mutex_.enabled_)
+      return event_.maybe_unlock_and_signal_one(lock);
+    else
+      return false;
+  }
+
+  // Reset the event.
+  void clear(conditionally_enabled_mutex::scoped_lock& lock)
+  {
+    if (lock.mutex_.enabled_)
+      event_.clear(lock);
+  }
+
+  // Wait for the event to become signalled.
+  void wait(conditionally_enabled_mutex::scoped_lock& lock)
+  {
+    if (lock.mutex_.enabled_)
+      event_.wait(lock);
+    else
+      null_event().wait(lock);
+  }
+
+  // Timed wait for the event to become signalled.
+  bool wait_for_usec(
+      conditionally_enabled_mutex::scoped_lock& lock, long usec)
+  {
+    if (lock.mutex_.enabled_)
+      return event_.wait_for_usec(lock, usec);
+    else
+      return null_event().wait_for_usec(lock, usec);
+  }
+
+private:
+  boost::asio::detail::event event_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_EVENT_HPP
diff --git a/include/boost/asio/detail/conditionally_enabled_mutex.hpp b/include/boost/asio/detail/conditionally_enabled_mutex.hpp
new file mode 100644
index 0000000000..c7762b6889
--- /dev/null
+++ b/include/boost/asio/detail/conditionally_enabled_mutex.hpp
@@ -0,0 +1,151 @@
+//
+// detail/conditionally_enabled_mutex.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP
+#define BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/mutex.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/scoped_lock.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+// Mutex adapter used to conditionally enable or disable locking.
+class conditionally_enabled_mutex
+  : private noncopyable
+{
+public:
+  // Helper class to lock and unlock a mutex automatically.
+  class scoped_lock
+    : private noncopyable
+  {
+  public:
+    // Tag type used to distinguish constructors.
+    enum adopt_lock_t { adopt_lock };
+
+    // Constructor adopts a lock that is already held.
+    scoped_lock(conditionally_enabled_mutex& m, adopt_lock_t)
+      : mutex_(m),
+        locked_(m.enabled_)
+    {
+    }
+
+    // Constructor acquires the lock.
+    explicit scoped_lock(conditionally_enabled_mutex& m)
+      : mutex_(m)
+    {
+      if (m.enabled_)
+      {
+        mutex_.mutex_.lock();
+        locked_ = true;
+      }
+      else
+        locked_ = false;
+    }
+
+    // Destructor releases the lock.
+    ~scoped_lock()
+    {
+      if (locked_)
+        mutex_.mutex_.unlock();
+    }
+
+    // Explicitly acquire the lock.
+    void lock()
+    {
+      if (mutex_.enabled_ && !locked_)
+      {
+        mutex_.mutex_.lock();
+        locked_ = true;
+      }
+    }
+
+    // Explicitly release the lock.
+    void unlock()
+    {
+      if (locked_)
+      {
+        mutex_.unlock();
+        locked_ = false;
+      }
+    }
+
+    // Test whether the lock is held.
+    bool locked() const
+    {
+      return locked_;
+    }
+
+    // Get the underlying mutex.
+    boost::asio::detail::mutex& mutex()
+    {
+      return mutex_.mutex_;
+    }
+
+  private:
+    friend class conditionally_enabled_event;
+    conditionally_enabled_mutex& mutex_;
+    bool locked_;
+  };
+
+  // Constructor.
+  explicit conditionally_enabled_mutex(bool enabled)
+    : enabled_(enabled)
+  {
+  }
+
+  // Destructor.
+  ~conditionally_enabled_mutex()
+  {
+  }
+
+  // Determine whether locking is enabled.
+  bool enabled() const
+  {
+    return enabled_;
+  }
+
+  // Lock the mutex.
+  void lock()
+  {
+    if (enabled_)
+      mutex_.lock();
+  }
+
+  // Unlock the mutex.
+  void unlock()
+  {
+    if (enabled_)
+      mutex_.unlock();
+  }
+
+private:
+  friend class scoped_lock;
+  friend class conditionally_enabled_event;
+  boost::asio::detail::mutex mutex_;
+  const bool enabled_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP
diff --git a/include/boost/asio/detail/config.hpp b/include/boost/asio/detail/config.hpp
index afe400e5b7..02fe78b61c 100644
--- a/include/boost/asio/detail/config.hpp
+++ b/include/boost/asio/detail/config.hpp
@@ -83,6 +83,11 @@
 # endif // (__cplusplus >= 201103)
 #endif // defined(__clang__)
 
+// Android platform detection.
+#if defined(__ANDROID__)
+# include <android/api-level.h>
+#endif // defined(__ANDROID__)
+
 // Support move construction and assignment on compilers known to allow it.
 #if !defined(BOOST_ASIO_HAS_MOVE)
 # if !defined(BOOST_ASIO_DISABLE_MOVE)
@@ -111,6 +116,7 @@
 // references and perfect forwarding.
 #if defined(BOOST_ASIO_HAS_MOVE) && !defined(BOOST_ASIO_MOVE_CAST)
 # define BOOST_ASIO_MOVE_ARG(type) type&&
+# define BOOST_ASIO_MOVE_ARG2(type1, type2) type1, type2&&
 # define BOOST_ASIO_MOVE_CAST(type) static_cast<type&&>
 # define BOOST_ASIO_MOVE_CAST2(type1, type2) static_cast<type1, type2&&>
 #endif // defined(BOOST_ASIO_HAS_MOVE) && !defined(BOOST_ASIO_MOVE_CAST)
@@ -163,6 +169,30 @@
 # endif // !defined(BOOST_ASIO_DISABLE_VARIADIC_TEMPLATES)
 #endif // !defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 
+// Support deleted functions on compilers known to allow it.
+#if !defined(BOOST_ASIO_DELETED)
+# if defined(__GNUC__)
+#  if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#   if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#    define BOOST_ASIO_DELETED = delete
+#   endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#  endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+# endif // defined(__GNUC__)
+# if defined(__clang__)
+#  if __has_feature(__cxx_deleted_functions__)
+#   define BOOST_ASIO_DELETED = delete
+#  endif // __has_feature(__cxx_deleted_functions__)
+# endif // defined(__clang__)
+# if defined(BOOST_ASIO_MSVC)
+#  if (_MSC_VER >= 1900)
+#   define BOOST_ASIO_DELETED = delete
+#  endif // (_MSC_VER >= 1900)
+# endif // defined(BOOST_ASIO_MSVC)
+# if !defined(BOOST_ASIO_DELETED)
+#  define BOOST_ASIO_DELETED
+# endif // !defined(BOOST_ASIO_DELETED)
+#endif // !defined(BOOST_ASIO_DELETED)
+
 // Support constexpr on compilers known to allow it.
 #if !defined(BOOST_ASIO_HAS_CONSTEXPR)
 # if !defined(BOOST_ASIO_DISABLE_CONSTEXPR)
@@ -193,6 +223,85 @@
 # endif // defined(BOOST_ASIO_HAS_CONSTEXPR)
 #endif // !defined(BOOST_ASIO_CONSTEXPR)
 
+// Support noexcept on compilers known to allow it.
+#if !defined(BOOST_ASIO_NOEXCEPT)
+# if !defined(BOOST_ASIO_DISABLE_NOEXCEPT)
+#  if (BOOST_VERSION >= 105300)
+#   define BOOST_ASIO_NOEXCEPT BOOST_NOEXCEPT
+#   define BOOST_ASIO_NOEXCEPT_OR_NOTHROW BOOST_NOEXCEPT_OR_NOTHROW
+#  elif defined(__clang__)
+#   if __has_feature(__cxx_noexcept__)
+#    define BOOST_ASIO_NOEXCEPT noexcept(true)
+#    define BOOST_ASIO_NOEXCEPT_OR_NOTHROW noexcept(true)
+#   endif // __has_feature(__cxx_noexcept__)
+#  elif defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#      define BOOST_ASIO_NOEXCEPT noexcept(true)
+#      define BOOST_ASIO_NOEXCEPT_OR_NOTHROW noexcept(true)
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#  elif defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1900)
+#    define BOOST_ASIO_NOEXCEPT noexcept(true)
+#    define BOOST_ASIO_NOEXCEPT_OR_NOTHROW noexcept(true)
+#   endif // (_MSC_VER >= 1900)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_NOEXCEPT)
+# if !defined(BOOST_ASIO_NOEXCEPT)
+#  define BOOST_ASIO_NOEXCEPT
+# endif // !defined(BOOST_ASIO_NOEXCEPT)
+# if !defined(BOOST_ASIO_NOEXCEPT_OR_NOTHROW)
+#  define BOOST_ASIO_NOEXCEPT_OR_NOTHROW throw()
+# endif // !defined(BOOST_ASIO_NOEXCEPT_OR_NOTHROW)
+#endif // !defined(BOOST_ASIO_NOEXCEPT)
+
+// Support automatic type deduction on compilers known to support it.
+#if !defined(BOOST_ASIO_HAS_DECLTYPE)
+# if !defined(BOOST_ASIO_DISABLE_DECLTYPE)
+#  if defined(__clang__)
+#   if __has_feature(__cxx_decltype__)
+#    define BOOST_ASIO_HAS_DECLTYPE 1
+#   endif // __has_feature(__cxx_decltype__)
+#  endif // defined(__clang__)
+#  if defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 6)) || (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#     define BOOST_ASIO_HAS_DECLTYPE 1
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 6)) || (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1700)
+#    define BOOST_ASIO_HAS_DECLTYPE 1
+#   endif // (_MSC_VER >= 1700)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_DECLTYPE)
+#endif // !defined(BOOST_ASIO_HAS_DECLTYPE)
+
+// Support alias templates on compilers known to allow it.
+#if !defined(BOOST_ASIO_HAS_ALIAS_TEMPLATES)
+# if !defined(BOOST_ASIO_DISABLE_ALIAS_TEMPLATES)
+#  if defined(__clang__)
+#   if __has_feature(__cxx_alias_templates__)
+#    define BOOST_ASIO_HAS_ALIAS_TEMPLATES 1
+#   endif // __has_feature(__cxx_alias_templates__)
+#  endif // defined(__clang__)
+#  if defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#     define BOOST_ASIO_HAS_ALIAS_TEMPLATES 1
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1900)
+#    define BOOST_ASIO_HAS_ALIAS_TEMPLATES 1
+#   endif // (_MSC_VER >= 1900)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_ALIAS_TEMPLATES)
+#endif // !defined(BOOST_ASIO_HAS_ALIAS_TEMPLATES)
+
 // Standard library support for system errors.
 # if !defined(BOOST_ASIO_DISABLE_STD_SYSTEM_ERROR)
 #  if defined(__clang__)
@@ -294,6 +403,31 @@
 # endif // !defined(BOOST_ASIO_DISABLE_STD_SHARED_PTR)
 #endif // !defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
 
+// Standard library support for allocator_arg_t.
+#if !defined(BOOST_ASIO_HAS_STD_ALLOCATOR_ARG)
+# if !defined(BOOST_ASIO_DISABLE_STD_ALLOCATOR_ARG)
+#  if defined(__clang__)
+#   if defined(BOOST_ASIO_HAS_CLANG_LIBCXX)
+#    define BOOST_ASIO_HAS_STD_ALLOCATOR_ARG 1
+#   elif (__cplusplus >= 201103)
+#    define BOOST_ASIO_HAS_STD_ALLOCATOR_ARG 1
+#   endif // (__cplusplus >= 201103)
+#  endif // defined(__clang__)
+#  if defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 6)) || (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#     define BOOST_ASIO_HAS_STD_ALLOCATOR_ARG 1
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 6)) || (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1600)
+#    define BOOST_ASIO_HAS_STD_ALLOCATOR_ARG 1
+#   endif // (_MSC_VER >= 1600)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_STD_ALLOCATOR_ARG)
+#endif // !defined(BOOST_ASIO_HAS_STD_ALLOCATOR_ARG)
+
 // Standard library support for atomic operations.
 #if !defined(BOOST_ASIO_HAS_STD_ATOMIC)
 # if !defined(BOOST_ASIO_DISABLE_STD_ATOMIC)
@@ -362,6 +496,15 @@
 # endif // !defined(BOOST_ASIO_DISABLE_BOOST_CHRONO)
 #endif // !defined(BOOST_ASIO_HAS_BOOST_CHRONO)
 
+// Some form of chrono library is available.
+#if !defined(BOOST_ASIO_HAS_CHRONO)
+# if defined(BOOST_ASIO_HAS_STD_CHRONO) \
+    || defined(BOOST_ASIO_HAS_BOOST_CHRONO)
+#  define BOOST_ASIO_HAS_CHRONO 1
+# endif // defined(BOOST_ASIO_HAS_STD_CHRONO)
+        // || defined(BOOST_ASIO_HAS_BOOST_CHRONO)
+#endif // !defined(BOOST_ASIO_HAS_CHRONO)
+
 // Boost support for the DateTime library.
 #if !defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 # if !defined(BOOST_ASIO_DISABLE_BOOST_DATE_TIME)
@@ -446,6 +589,28 @@
 # endif // !defined(BOOST_ASIO_DISABLE_STD_TYPE_TRAITS)
 #endif // !defined(BOOST_ASIO_HAS_STD_TYPE_TRAITS)
 
+// Standard library support for the nullptr_t type.
+#if !defined(BOOST_ASIO_HAS_NULLPTR)
+# if !defined(BOOST_ASIO_DISABLE_NULLPTR)
+#  if defined(__clang__)
+#   if __has_feature(__cxx_nullptr__)
+#    define BOOST_ASIO_HAS_NULLPTR 1
+#   endif // __has_feature(__cxx_rvalue_references__)
+#  elif defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 6)) || (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#     define BOOST_ASIO_HAS_NULLPTR 1
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 6)) || (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1700)
+#    define BOOST_ASIO_HAS_NULLPTR 1
+#   endif // (_MSC_VER >= 1700)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_NULLPTR)
+#endif // !defined(BOOST_ASIO_HAS_NULLPTR)
+
 // Standard library support for the C++11 allocator additions.
 #if !defined(BOOST_ASIO_HAS_CXX11_ALLOCATORS)
 # if !defined(BOOST_ASIO_DISABLE_CXX11_ALLOCATORS)
@@ -549,6 +714,105 @@
 # endif // !defined(BOOST_ASIO_DISABLE_STD_MUTEX_AND_CONDVAR)
 #endif // !defined(BOOST_ASIO_HAS_STD_MUTEX_AND_CONDVAR)
 
+// Standard library support for the call_once function.
+#if !defined(BOOST_ASIO_HAS_STD_CALL_ONCE)
+# if !defined(BOOST_ASIO_DISABLE_STD_CALL_ONCE)
+#  if defined(__clang__)
+#   if defined(BOOST_ASIO_HAS_CLANG_LIBCXX)
+#    define BOOST_ASIO_HAS_STD_CALL_ONCE 1
+#   elif (__cplusplus >= 201103)
+#    if __has_include(<mutex>)
+#     define BOOST_ASIO_HAS_STD_CALL_ONCE 1
+#    endif // __has_include(<mutex>)
+#   endif // (__cplusplus >= 201103)
+#  endif // defined(__clang__)
+#  if defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#     define BOOST_ASIO_HAS_STD_CALL_ONCE 1
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1700)
+#    define BOOST_ASIO_HAS_STD_CALL_ONCE 1
+#   endif // (_MSC_VER >= 1700)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_STD_CALL_ONCE)
+#endif // !defined(BOOST_ASIO_HAS_STD_CALL_ONCE)
+
+// Standard library support for futures.
+#if !defined(BOOST_ASIO_HAS_STD_FUTURE)
+# if !defined(BOOST_ASIO_DISABLE_STD_FUTURE)
+#  if defined(__clang__)
+#   if defined(BOOST_ASIO_HAS_CLANG_LIBCXX)
+#    define BOOST_ASIO_HAS_STD_FUTURE 1
+#   elif (__cplusplus >= 201103)
+#    if __has_include(<future>)
+#     define BOOST_ASIO_HAS_STD_FUTURE 1
+#    endif // __has_include(<mutex>)
+#   endif // (__cplusplus >= 201103)
+#  endif // defined(__clang__)
+#  if defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#     define BOOST_ASIO_HAS_STD_FUTURE 1
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1700)
+#    define BOOST_ASIO_HAS_STD_FUTURE 1
+#   endif // (_MSC_VER >= 1700)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_STD_FUTURE)
+#endif // !defined(BOOST_ASIO_HAS_STD_FUTURE)
+
+// Standard library support for experimental::string_view.
+#if !defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# if !defined(BOOST_ASIO_DISABLE_STD_STRING_VIEW)
+#  if defined(__clang__)
+#   if (__cplusplus >= 201402)
+#    if __has_include(<experimental/string_view>)
+#     define BOOST_ASIO_HAS_STD_STRING_VIEW 1
+#     define BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW 1
+#    endif // __has_include(<experimental/string_view>)
+#   endif // (__cplusplus >= 201402)
+#  endif // defined(__clang__)
+#  if defined(__GNUC__)
+#   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 9)) || (__GNUC__ > 4)
+#    if (__cplusplus >= 201402)
+#     define BOOST_ASIO_HAS_STD_STRING_VIEW 1
+#     define BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW 1
+#    endif // (__cplusplus >= 201402)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1910 && _HAS_CXX17)
+#    define BOOST_ASIO_HAS_STD_STRING_VIEW
+#   endif // (_MSC_VER >= 1910)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_STD_STRING_VIEW)
+#endif // !defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+// Standard library support for iostream move construction and assignment.
+#if !defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)
+# if !defined(BOOST_ASIO_DISABLE_STD_IOSTREAM_MOVE)
+#  if defined(__GNUC__)
+#   if (__GNUC__ > 4)
+#    if defined(__GXX_EXPERIMENTAL_CXX0X__)
+#     define BOOST_ASIO_HAS_STD_IOSTREAM_MOVE 1
+#    endif // defined(__GXX_EXPERIMENTAL_CXX0X__)
+#   endif // (__GNUC__ > 4)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1700)
+#    define BOOST_ASIO_HAS_STD_IOSTREAM_MOVE 1
+#   endif // (_MSC_VER >= 1700)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_STD_IOSTREAM_MOVE)
+#endif // !defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)
+
 // Windows App target. Windows but with a limited API.
 #if !defined(BOOST_ASIO_WINDOWS_APP)
 # if defined(_WIN32_WINNT) && (_WIN32_WINNT >= 0x0603)
@@ -884,11 +1148,18 @@
 # if !defined(BOOST_ASIO_DISABLE_THREADS)
 #  if defined(BOOST_ASIO_HAS_BOOST_CONFIG) && defined(BOOST_HAS_THREADS)
 #   define BOOST_ASIO_HAS_THREADS 1
-#  elif defined(_MSC_VER) && defined(_MT)
+#  elif defined(__GNUC__) && !defined(__MINGW32__) \
+     && !defined(linux) && !defined(__linux) && !defined(__linux__)
+#   define BOOST_ASIO_HAS_THREADS 1
+#  elif defined(_MT) || defined(__MT__)
+#   define BOOST_ASIO_HAS_THREADS 1
+#  elif defined(_REENTRANT)
 #   define BOOST_ASIO_HAS_THREADS 1
-#  elif defined(__BORLANDC__) && defined(__MT__)
+#  elif defined(__APPLE__)
 #   define BOOST_ASIO_HAS_THREADS 1
-#  elif defined(_POSIX_THREADS)
+#  elif defined(_POSIX_THREADS) && (_POSIX_THREADS + 0 >= 0)
+#   define BOOST_ASIO_HAS_THREADS 1
+#  elif defined(_PTHREADS)
 #   define BOOST_ASIO_HAS_THREADS 1
 #  endif // defined(BOOST_ASIO_HAS_BOOST_CONFIG) && defined(BOOST_HAS_THREADS)
 # endif // !defined(BOOST_ASIO_DISABLE_THREADS)
@@ -899,7 +1170,7 @@
 # if defined(BOOST_ASIO_HAS_THREADS)
 #  if defined(BOOST_ASIO_HAS_BOOST_CONFIG) && defined(BOOST_HAS_PTHREADS)
 #   define BOOST_ASIO_HAS_PTHREADS 1
-#  elif defined(_POSIX_THREADS)
+#  elif defined(_POSIX_THREADS) && (_POSIX_THREADS + 0 >= 0)
 #   define BOOST_ASIO_HAS_PTHREADS 1
 #  endif // defined(BOOST_ASIO_HAS_BOOST_CONFIG) && defined(BOOST_HAS_PTHREADS)
 # endif // defined(BOOST_ASIO_HAS_THREADS)
@@ -1030,17 +1301,45 @@
         //   || (defined(__MACH__) && defined(__APPLE__))
 #endif // !defined(BOOST_ASIO_DISABLE_SSIZE_T)
 
+// Helper macros to manage the transition away from the old services-based API.
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# define BOOST_ASIO_SVC_TPARAM , typename Service
+# define BOOST_ASIO_SVC_TPARAM_DEF1(d1) , typename Service d1
+# define BOOST_ASIO_SVC_TPARAM_DEF2(d1, d2) , typename Service d1, d2
+# define BOOST_ASIO_SVC_TARG , Service
+# define BOOST_ASIO_SVC_T Service
+# define BOOST_ASIO_SVC_TPARAM1 , typename Service1
+# define BOOST_ASIO_SVC_TPARAM1_DEF1(d1) , typename Service1 d1
+# define BOOST_ASIO_SVC_TPARAM1_DEF2(d1, d2) , typename Service1 d1, d2
+# define BOOST_ASIO_SVC_TARG1 , Service1
+# define BOOST_ASIO_SVC_T1 Service1
+# define BOOST_ASIO_SVC_ACCESS public
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# define BOOST_ASIO_SVC_TPARAM
+# define BOOST_ASIO_SVC_TPARAM_DEF1(d1)
+# define BOOST_ASIO_SVC_TPARAM_DEF2(d1, d2)
+# define BOOST_ASIO_SVC_TARG
+// BOOST_ASIO_SVC_T is defined at each point of use.
+# define BOOST_ASIO_SVC_TPARAM1
+# define BOOST_ASIO_SVC_TPARAM1_DEF1(d1)
+# define BOOST_ASIO_SVC_TPARAM1_DEF2(d1, d2)
+# define BOOST_ASIO_SVC_TARG1
+// BOOST_ASIO_SVC_T1 is defined at each point of use.
+# define BOOST_ASIO_SVC_ACCESS protected
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+// Helper macros to manage transition away from error_code return values.
+#if defined(BOOST_ASIO_NO_DEPRECATED)
+# define BOOST_ASIO_SYNC_OP_VOID void
+# define BOOST_ASIO_SYNC_OP_VOID_RETURN(e) return
+#else // defined(BOOST_ASIO_NO_DEPRECATED)
+# define BOOST_ASIO_SYNC_OP_VOID boost::system::error_code
+# define BOOST_ASIO_SYNC_OP_VOID_RETURN(e) return e
+#endif // defined(BOOST_ASIO_NO_DEPRECATED)
+
 // Newer gcc, clang need special treatment to suppress unused typedef warnings.
-#if defined(__clang__)
-# if defined(__apple_build_version__)
-#  if (__clang_major__ >= 7)
-#   define BOOST_ASIO_UNUSED_TYPEDEF __attribute__((__unused__))
-#  endif // (__clang_major__ >= 7)
-# elif ((__clang_major__ == 3) && (__clang_minor__ >= 6)) \
-    || (__clang_major__ > 3)
-#  define BOOST_ASIO_UNUSED_TYPEDEF __attribute__((__unused__))
-# endif // ((__clang_major__ == 3) && (__clang_minor__ >= 6))
-        //   || (__clang_major__ > 3)
+#if defined(__clang__) && (__clang_major__ >= 7)
+# define BOOST_ASIO_UNUSED_TYPEDEF __attribute__((__unused__))
 #elif defined(__GNUC__)
 # if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)) || (__GNUC__ > 4)
 #  define BOOST_ASIO_UNUSED_TYPEDEF __attribute__((__unused__))
diff --git a/include/boost/asio/detail/consuming_buffers.hpp b/include/boost/asio/detail/consuming_buffers.hpp
index f0978b54d3..8ac39e2cbe 100644
--- a/include/boost/asio/detail/consuming_buffers.hpp
+++ b/include/boost/asio/detail/consuming_buffers.hpp
@@ -17,8 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
-#include <iterator>
 #include <boost/asio/buffer.hpp>
+#include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/limits.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -27,262 +27,363 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-// A proxy iterator for a sub-range in a list of buffers.
-template <typename Buffer, typename Buffer_Iterator>
-class consuming_buffers_iterator
-{
-public:
-  /// The type used for the distance between two iterators.
-  typedef std::ptrdiff_t difference_type;
 
-  /// The type of the value pointed to by the iterator.
+// A buffer sequence used to represent a subsequence of the buffers.
+template <typename Buffer>
+struct prepared_buffers
+{
   typedef Buffer value_type;
+  typedef const Buffer* const_iterator;
 
-  /// The type of the result of applying operator->() to the iterator.
-  typedef const Buffer* pointer;
+  enum
+  {
+    max_buffers = buffer_sequence_adapter_base::max_buffers < 8
+      ? buffer_sequence_adapter_base::max_buffers : 8
+  };
+
+  prepared_buffers() : count(0) {}
+  const_iterator begin() const { return elems; }
+  const_iterator end() const { return elems + count; }
 
-  /// The type of the result of applying operator*() to the iterator.
-  typedef const Buffer& reference;
+  Buffer elems[max_buffers];
+  std::size_t count;
+};
 
-  /// The iterator category.
-  typedef std::forward_iterator_tag iterator_category;
+// A proxy for a sub-range in a list of buffers.
+template <typename Buffer, typename Buffers, typename Buffer_Iterator>
+class consuming_buffers
+{
+public:
+  // Construct to represent the entire list of buffers.
+  explicit consuming_buffers(const Buffers& buffers)
+    : buffers_(buffers),
+      total_consumed_(0),
+      next_elem_(0),
+      next_elem_offset_(0)
+  {
+    using boost::asio::buffer_size;
+    total_size_ = buffer_size(buffers);
+  }
 
-  // Default constructor creates an end iterator.
-  consuming_buffers_iterator()
-    : at_end_(true)
+  // Determine if we are at the end of the buffers.
+  bool empty() const
   {
+    return total_consumed_ >= total_size_;
   }
 
-  // Construct with a buffer for the first entry and an iterator
-  // range for the remaining entries.
-  consuming_buffers_iterator(bool at_end, const Buffer& first,
-      Buffer_Iterator begin_remainder, Buffer_Iterator end_remainder,
-      std::size_t max_size)
-    : at_end_(max_size > 0 ? at_end : true),
-      first_(buffer(first, max_size)),
-      begin_remainder_(begin_remainder),
-      end_remainder_(end_remainder),
-      offset_(0),
-      max_size_(max_size)
+  // Get the buffer for a single transfer, with a size.
+  prepared_buffers<Buffer> prepare(std::size_t max_size)
   {
+    prepared_buffers<Buffer> result;
+
+    Buffer_Iterator next = boost::asio::buffer_sequence_begin(buffers_);
+    Buffer_Iterator end = boost::asio::buffer_sequence_end(buffers_);
+
+    std::advance(next, next_elem_);
+    std::size_t elem_offset = next_elem_offset_;
+    while (next != end && max_size > 0 && result.count < result.max_buffers)
+    {
+      Buffer next_buf = Buffer(*next) + elem_offset;
+      result.elems[result.count] = boost::asio::buffer(next_buf, max_size);
+      max_size -= result.elems[result.count].size();
+      elem_offset = 0;
+      if (result.elems[result.count].size() > 0)
+        ++result.count;
+      ++next;
+    }
+
+    return result;
+  }
+
+  // Consume the specified number of bytes from the buffers.
+  void consume(std::size_t size)
+  {
+    total_consumed_ += size;
+
+    Buffer_Iterator next = boost::asio::buffer_sequence_begin(buffers_);
+    Buffer_Iterator end = boost::asio::buffer_sequence_end(buffers_);
+
+    std::advance(next, next_elem_);
+    while (next != end && size > 0)
+    {
+      Buffer next_buf = Buffer(*next) + next_elem_offset_;
+      if (size < next_buf.size())
+      {
+        next_elem_offset_ += size;
+        size = 0;
+      }
+      else
+      {
+        size -= next_buf.size();
+        next_elem_offset_ = 0;
+        ++next_elem_;
+        ++next;
+      }
+    }
   }
 
-  // Dereference an iterator.
-  const Buffer& operator*() const
+  // Get the total number of bytes consumed from the buffers.
+  std::size_t total_consumed() const
   {
-    return dereference();
+    return total_consumed_;
   }
 
-  // Dereference an iterator.
-  const Buffer* operator->() const
+private:
+  Buffers buffers_;
+  std::size_t total_size_;
+  std::size_t total_consumed_;
+  std::size_t next_elem_;
+  std::size_t next_elem_offset_;
+};
+
+// Base class of all consuming_buffers specialisations for single buffers.
+template <typename Buffer>
+class consuming_single_buffer
+{
+public:
+  // Construct to represent the entire list of buffers.
+  template <typename Buffer1>
+  explicit consuming_single_buffer(const Buffer1& buffer)
+    : buffer_(buffer),
+      total_consumed_(0)
   {
-    return &dereference();
   }
 
-  // Increment operator (prefix).
-  consuming_buffers_iterator& operator++()
+  // Determine if we are at the end of the buffers.
+  bool empty() const
   {
-    increment();
-    return *this;
+    return total_consumed_ >= buffer_.size();
   }
 
-  // Increment operator (postfix).
-  consuming_buffers_iterator operator++(int)
+  // Get the buffer for a single transfer, with a size.
+  Buffer prepare(std::size_t max_size)
   {
-    consuming_buffers_iterator tmp(*this);
-    ++*this;
-    return tmp;
+    return boost::asio::buffer(buffer_ + total_consumed_, max_size);
   }
 
-  // Test two iterators for equality.
-  friend bool operator==(const consuming_buffers_iterator& a,
-      const consuming_buffers_iterator& b)
+  // Consume the specified number of bytes from the buffers.
+  void consume(std::size_t size)
   {
-    return a.equal(b);
+    total_consumed_ += size;
   }
 
-  // Test two iterators for inequality.
-  friend bool operator!=(const consuming_buffers_iterator& a,
-      const consuming_buffers_iterator& b)
+  // Get the total number of bytes consumed from the buffers.
+  std::size_t total_consumed() const
   {
-    return !a.equal(b);
+    return total_consumed_;
   }
 
 private:
-  void increment()
+  Buffer buffer_;
+  std::size_t total_consumed_;
+};
+
+template <>
+class consuming_buffers<mutable_buffer, mutable_buffer, const mutable_buffer*>
+  : public consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER>
+{
+public:
+  explicit consuming_buffers(const mutable_buffer& buffer)
+    : consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER>(buffer)
+  {
+  }
+};
+
+template <>
+class consuming_buffers<const_buffer, mutable_buffer, const mutable_buffer*>
+  : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>
+{
+public:
+  explicit consuming_buffers(const mutable_buffer& buffer)
+    : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer)
   {
-    if (!at_end_)
-    {
-      if (begin_remainder_ == end_remainder_
-          || offset_ + buffer_size(first_) >= max_size_)
-      {
-        at_end_ = true;
-      }
-      else
-      {
-        offset_ += buffer_size(first_);
-        first_ = buffer(*begin_remainder_++, max_size_ - offset_);
-      }
-    }
   }
+};
 
-  bool equal(const consuming_buffers_iterator& other) const
+template <>
+class consuming_buffers<const_buffer, const_buffer, const const_buffer*>
+  : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>
+{
+public:
+  explicit consuming_buffers(const const_buffer& buffer)
+    : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer)
   {
-    if (at_end_ && other.at_end_)
-      return true;
-    return !at_end_ && !other.at_end_
-      && buffer_cast<const void*>(first_)
-        == buffer_cast<const void*>(other.first_)
-      && buffer_size(first_) == buffer_size(other.first_)
-      && begin_remainder_ == other.begin_remainder_
-      && end_remainder_ == other.end_remainder_;
   }
+};
 
-  const Buffer& dereference() const
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+template <>
+class consuming_buffers<mutable_buffer,
+    mutable_buffers_1, const mutable_buffer*>
+  : public consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER>
+{
+public:
+  explicit consuming_buffers(const mutable_buffers_1& buffer)
+    : consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER>(buffer)
   {
-    return first_;
   }
+};
 
-  bool at_end_;
-  Buffer first_;
-  Buffer_Iterator begin_remainder_;
-  Buffer_Iterator end_remainder_;
-  std::size_t offset_;
-  std::size_t max_size_;
+template <>
+class consuming_buffers<const_buffer, mutable_buffers_1, const mutable_buffer*>
+  : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>
+{
+public:
+  explicit consuming_buffers(const mutable_buffers_1& buffer)
+    : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer)
+  {
+  }
 };
 
-// A proxy for a sub-range in a list of buffers.
-template <typename Buffer, typename Buffers>
-class consuming_buffers
+template <>
+class consuming_buffers<const_buffer, const_buffers_1, const const_buffer*>
+  : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>
 {
 public:
-  // The type for each element in the list of buffers.
-  typedef Buffer value_type;
+  explicit consuming_buffers(const const_buffers_1& buffer)
+    : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer)
+  {
+  }
+};
 
-  // A forward-only iterator type that may be used to read elements.
-  typedef consuming_buffers_iterator<Buffer, typename Buffers::const_iterator>
-    const_iterator;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
+template <typename Buffer, typename Elem>
+class consuming_buffers<Buffer, boost::array<Elem, 2>,
+    typename boost::array<Elem, 2>::const_iterator>
+{
+public:
   // Construct to represent the entire list of buffers.
-  consuming_buffers(const Buffers& buffers)
+  explicit consuming_buffers(const boost::array<Elem, 2>& buffers)
     : buffers_(buffers),
-      at_end_(buffers_.begin() == buffers_.end()),
-      begin_remainder_(buffers_.begin()),
-      max_size_((std::numeric_limits<std::size_t>::max)())
+      total_consumed_(0)
   {
-    if (!at_end_)
-    {
-      first_ = *buffers_.begin();
-      ++begin_remainder_;
-    }
   }
 
-  // Copy constructor.
-  consuming_buffers(const consuming_buffers& other)
-    : buffers_(other.buffers_),
-      at_end_(other.at_end_),
-      first_(other.first_),
-      begin_remainder_(buffers_.begin()),
-      max_size_(other.max_size_)
-  {
-    typename Buffers::const_iterator first = other.buffers_.begin();
-    typename Buffers::const_iterator second = other.begin_remainder_;
-    std::advance(begin_remainder_, std::distance(first, second));
+  // Determine if we are at the end of the buffers.
+  bool empty() const
+  {
+    return total_consumed_ >=
+      Buffer(buffers_[0]).size() + Buffer(buffers_[1]).size();
+  }
+
+  // Get the buffer for a single transfer, with a size.
+  boost::array<Buffer, 2> prepare(std::size_t max_size)
+  {
+    boost::array<Buffer, 2> result = {{
+      Buffer(buffers_[0]), Buffer(buffers_[1]) }};
+    std::size_t buffer0_size = result[0].size();
+    result[0] = boost::asio::buffer(result[0] + total_consumed_, max_size);
+    result[1] = boost::asio::buffer(
+        result[1] + (total_consumed_ < buffer0_size
+          ? 0 : total_consumed_ - buffer0_size),
+        max_size - result[0].size());
+    return result;
+  }
+
+  // Consume the specified number of bytes from the buffers.
+  void consume(std::size_t size)
+  {
+    total_consumed_ += size;
   }
 
-  // Assignment operator.
-  consuming_buffers& operator=(const consuming_buffers& other)
-  {
-    buffers_ = other.buffers_;
-    at_end_ = other.at_end_;
-    first_ = other.first_;
-    begin_remainder_ = buffers_.begin();
-    typename Buffers::const_iterator first = other.buffers_.begin();
-    typename Buffers::const_iterator second = other.begin_remainder_;
-    std::advance(begin_remainder_, std::distance(first, second));
-    max_size_ = other.max_size_;
-    return *this;
+  // Get the total number of bytes consumed from the buffers.
+  std::size_t total_consumed() const
+  {
+    return total_consumed_;
   }
 
-  // Get a forward-only iterator to the first element.
-  const_iterator begin() const
+private:
+  boost::array<Elem, 2> buffers_;
+  std::size_t total_consumed_;
+};
+
+#if defined(BOOST_ASIO_HAS_STD_ARRAY)
+
+template <typename Buffer, typename Elem>
+class consuming_buffers<Buffer, std::array<Elem, 2>,
+    typename std::array<Elem, 2>::const_iterator>
+{
+public:
+  // Construct to represent the entire list of buffers.
+  explicit consuming_buffers(const std::array<Elem, 2>& buffers)
+    : buffers_(buffers),
+      total_consumed_(0)
   {
-    return const_iterator(at_end_, first_,
-        begin_remainder_, buffers_.end(), max_size_);
   }
 
-  // Get a forward-only iterator for one past the last element.
-  const_iterator end() const
+  // Determine if we are at the end of the buffers.
+  bool empty() const
   {
-    return const_iterator();
+    return total_consumed_ >=
+      Buffer(buffers_[0]).size() + Buffer(buffers_[1]).size();
   }
 
-  // Set the maximum size for a single transfer.
-  void prepare(std::size_t max_size)
+  // Get the buffer for a single transfer, with a size.
+  std::array<Buffer, 2> prepare(std::size_t max_size)
   {
-    max_size_ = max_size;
+    std::array<Buffer, 2> result = {{
+      Buffer(buffers_[0]), Buffer(buffers_[1]) }};
+    std::size_t buffer0_size = result[0].size();
+    result[0] = boost::asio::buffer(result[0] + total_consumed_, max_size);
+    result[1] = boost::asio::buffer(
+        result[1] + (total_consumed_ < buffer0_size
+          ? 0 : total_consumed_ - buffer0_size),
+        max_size - result[0].size());
+    return result;
   }
 
   // Consume the specified number of bytes from the buffers.
   void consume(std::size_t size)
   {
-    // Remove buffers from the start until the specified size is reached.
-    while (size > 0 && !at_end_)
-    {
-      if (buffer_size(first_) <= size)
-      {
-        size -= buffer_size(first_);
-        if (begin_remainder_ == buffers_.end())
-          at_end_ = true;
-        else
-          first_ = *begin_remainder_++;
-      }
-      else
-      {
-        first_ = first_ + size;
-        size = 0;
-      }
-    }
+    total_consumed_ += size;
+  }
 
-    // Remove any more empty buffers at the start.
-    while (!at_end_ && buffer_size(first_) == 0)
-    {
-      if (begin_remainder_ == buffers_.end())
-        at_end_ = true;
-      else
-        first_ = *begin_remainder_++;
-    }
+  // Get the total number of bytes consumed from the buffers.
+  std::size_t total_consumed() const
+  {
+    return total_consumed_;
   }
 
 private:
-  Buffers buffers_;
-  bool at_end_;
-  Buffer first_;
-  typename Buffers::const_iterator begin_remainder_;
-  std::size_t max_size_;
+  std::array<Elem, 2> buffers_;
+  std::size_t total_consumed_;
 };
 
+#endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
+
 // Specialisation for null_buffers to ensure that the null_buffers type is
 // always passed through to the underlying read or write operation.
 template <typename Buffer>
-class consuming_buffers<Buffer, boost::asio::null_buffers>
+class consuming_buffers<Buffer, null_buffers, const mutable_buffer*>
   : public boost::asio::null_buffers
 {
 public:
-  consuming_buffers(const boost::asio::null_buffers&)
+  consuming_buffers(const null_buffers&)
   {
     // No-op.
   }
 
-  void prepare(std::size_t)
+  bool empty()
   {
-    // No-op.
+    return false;
+  }
+
+  null_buffers prepare(std::size_t)
+  {
+    return null_buffers();
   }
 
   void consume(std::size_t)
   {
     // No-op.
   }
+
+  std::size_t total_consume() const
+  {
+    return 0;
+  }
 };
 
 } // namespace detail
diff --git a/include/boost/asio/detail/cstddef.hpp b/include/boost/asio/detail/cstddef.hpp
new file mode 100644
index 0000000000..a6dacc1de4
--- /dev/null
+++ b/include/boost/asio/detail/cstddef.hpp
@@ -0,0 +1,33 @@
+//
+// detail/cstddef.hpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_CSTDDEF_HPP
+#define BOOST_ASIO_DETAIL_CSTDDEF_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <cstddef>
+
+namespace boost {
+namespace asio {
+
+#if defined(BOOST_ASIO_HAS_NULLPTR)
+using std::nullptr_t;
+#else // defined(BOOST_ASIO_HAS_NULLPTR)
+struct nullptr_t {};
+#endif // defined(BOOST_ASIO_HAS_NULLPTR)
+
+} // namespace asio
+} // namespace boost
+
+#endif // BOOST_ASIO_DETAIL_CSTDDEF_HPP
diff --git a/include/boost/asio/detail/cstdint.hpp b/include/boost/asio/detail/cstdint.hpp
index a1be0dced0..61627c7ed3 100644
--- a/include/boost/asio/detail/cstdint.hpp
+++ b/include/boost/asio/detail/cstdint.hpp
@@ -28,18 +28,32 @@ namespace asio {
 
 #if defined(BOOST_ASIO_HAS_CSTDINT)
 using std::int16_t;
+using std::int_least16_t;
 using std::uint16_t;
+using std::uint_least16_t;
 using std::int32_t;
+using std::int_least32_t;
 using std::uint32_t;
+using std::uint_least32_t;
 using std::int64_t;
+using std::int_least64_t;
 using std::uint64_t;
+using std::uint_least64_t;
+using std::uintmax_t;
 #else // defined(BOOST_ASIO_HAS_CSTDINT)
 using boost::int16_t;
+using boost::int_least16_t;
 using boost::uint16_t;
+using boost::uint_least16_t;
 using boost::int32_t;
+using boost::int_least32_t;
 using boost::uint32_t;
+using boost::uint_least32_t;
 using boost::int64_t;
+using boost::int_least64_t;
 using boost::uint64_t;
+using boost::uint_least64_t;
+using boost::uintmax_t;
 #endif // defined(BOOST_ASIO_HAS_CSTDINT)
 
 } // namespace asio
diff --git a/include/boost/asio/detail/deadline_timer_service.hpp b/include/boost/asio/detail/deadline_timer_service.hpp
index bbd5358425..bc17eb288c 100644
--- a/include/boost/asio/detail/deadline_timer_service.hpp
+++ b/include/boost/asio/detail/deadline_timer_service.hpp
@@ -18,14 +18,15 @@
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/detail/socket_types.hpp>
 #include <boost/asio/detail/timer_queue.hpp>
+#include <boost/asio/detail/timer_queue_ptime.hpp>
 #include <boost/asio/detail/timer_scheduler.hpp>
 #include <boost/asio/detail/wait_handler.hpp>
 #include <boost/asio/detail/wait_op.hpp>
@@ -43,6 +44,7 @@ namespace detail {
 
 template <typename Time_Traits>
 class deadline_timer_service
+  : public service_base<deadline_timer_service<Time_Traits> >
 {
 public:
   // The time type.
@@ -62,8 +64,9 @@ class deadline_timer_service
   };
 
   // Constructor.
-  deadline_timer_service(boost::asio::io_service& io_service)
-    : scheduler_(boost::asio::use_service<timer_scheduler>(io_service))
+  deadline_timer_service(boost::asio::io_context& io_context)
+    : service_base<deadline_timer_service<Time_Traits> >(io_context),
+      scheduler_(boost::asio::use_service<timer_scheduler>(io_context))
   {
     scheduler_.init_task();
     scheduler_.add_timer_queue(timer_queue_);
@@ -76,7 +79,7 @@ class deadline_timer_service
   }
 
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
   }
 
@@ -94,6 +97,38 @@ class deadline_timer_service
     cancel(impl, ec);
   }
 
+  // Move-construct a new serial port implementation.
+  void move_construct(implementation_type& impl,
+      implementation_type& other_impl)
+  {
+    scheduler_.move_timer(timer_queue_, impl.timer_data, other_impl.timer_data);
+
+    impl.expiry = other_impl.expiry;
+    other_impl.expiry = time_type();
+
+    impl.might_have_pending_waits = other_impl.might_have_pending_waits;
+    other_impl.might_have_pending_waits = false;
+  }
+
+  // Move-assign from another serial port implementation.
+  void move_assign(implementation_type& impl,
+      deadline_timer_service& other_service,
+      implementation_type& other_impl)
+  {
+    if (this != &other_service)
+      if (impl.might_have_pending_waits)
+        scheduler_.cancel_timer(timer_queue_, impl.timer_data);
+
+    other_service.scheduler_.move_timer(other_service.timer_queue_,
+        impl.timer_data, other_impl.timer_data);
+
+    impl.expiry = other_impl.expiry;
+    other_impl.expiry = time_type();
+
+    impl.might_have_pending_waits = other_impl.might_have_pending_waits;
+    other_impl.might_have_pending_waits = false;
+  }
+
   // Cancel any asynchronous wait operations associated with the timer.
   std::size_t cancel(implementation_type& impl, boost::system::error_code& ec)
   {
@@ -103,7 +138,8 @@ class deadline_timer_service
       return 0;
     }
 
-    BOOST_ASIO_HANDLER_OPERATION(("deadline_timer", &impl, "cancel"));
+    BOOST_ASIO_HANDLER_OPERATION((scheduler_.context(),
+          "deadline_timer", &impl, 0, "cancel"));
 
     std::size_t count = scheduler_.cancel_timer(timer_queue_, impl.timer_data);
     impl.might_have_pending_waits = false;
@@ -121,7 +157,8 @@ class deadline_timer_service
       return 0;
     }
 
-    BOOST_ASIO_HANDLER_OPERATION(("deadline_timer", &impl, "cancel_one"));
+    BOOST_ASIO_HANDLER_OPERATION((scheduler_.context(),
+          "deadline_timer", &impl, 0, "cancel_one"));
 
     std::size_t count = scheduler_.cancel_timer(
         timer_queue_, impl.timer_data, 1);
@@ -131,12 +168,24 @@ class deadline_timer_service
     return count;
   }
 
+  // Get the expiry time for the timer as an absolute time.
+  time_type expiry(const implementation_type& impl) const
+  {
+    return impl.expiry;
+  }
+
   // Get the expiry time for the timer as an absolute time.
   time_type expires_at(const implementation_type& impl) const
   {
     return impl.expiry;
   }
 
+  // Get the expiry time for the timer relative to now.
+  duration_type expires_from_now(const implementation_type& impl) const
+  {
+    return Time_Traits::subtract(this->expiry(impl), Time_Traits::now());
+  }
+
   // Set the expiry time for the timer as an absolute time.
   std::size_t expires_at(implementation_type& impl,
       const time_type& expiry_time, boost::system::error_code& ec)
@@ -147,10 +196,12 @@ class deadline_timer_service
     return count;
   }
 
-  // Get the expiry time for the timer relative to now.
-  duration_type expires_from_now(const implementation_type& impl) const
+  // Set the expiry time for the timer relative to now.
+  std::size_t expires_after(implementation_type& impl,
+      const duration_type& expiry_time, boost::system::error_code& ec)
   {
-    return Time_Traits::subtract(expires_at(impl), Time_Traits::now());
+    return expires_at(impl,
+        Time_Traits::add(Time_Traits::now(), expiry_time), ec);
   }
 
   // Set the expiry time for the timer relative to now.
@@ -181,13 +232,13 @@ class deadline_timer_service
     // Allocate and construct an operation to wrap the handler.
     typedef wait_handler<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
     impl.might_have_pending_waits = true;
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "deadline_timer", &impl, "async_wait"));
+    BOOST_ASIO_HANDLER_CREATION((scheduler_.context(),
+          *p.p, "deadline_timer", &impl, 0, "async_wait"));
 
     scheduler_.schedule_timer(timer_queue_, impl.expiry, impl.timer_data, p.p);
     p.v = p.p = 0;
diff --git a/include/boost/asio/detail/descriptor_ops.hpp b/include/boost/asio/detail/descriptor_ops.hpp
index 62100392da..5c1ce20d9c 100644
--- a/include/boost/asio/detail/descriptor_ops.hpp
+++ b/include/boost/asio/detail/descriptor_ops.hpp
@@ -22,6 +22,7 @@
   && !defined(__CYGWIN__)
 
 #include <cstddef>
+#include <boost/asio/error.hpp>
 #include <boost/system/error_code.hpp>
 #include <boost/asio/detail/socket_types.hpp>
 
@@ -101,6 +102,9 @@ BOOST_ASIO_DECL int poll_read(int d,
 BOOST_ASIO_DECL int poll_write(int d,
     state_type state, boost::system::error_code& ec);
 
+BOOST_ASIO_DECL int poll_error(int d,
+    state_type state, boost::system::error_code& ec);
+
 } // namespace descriptor_ops
 } // namespace detail
 } // namespace asio
diff --git a/include/boost/asio/detail/descriptor_read_op.hpp b/include/boost/asio/detail/descriptor_read_op.hpp
index ddbdf7d3e5..1ca2d236fe 100644
--- a/include/boost/asio/detail/descriptor_read_op.hpp
+++ b/include/boost/asio/detail/descriptor_read_op.hpp
@@ -19,11 +19,12 @@
 
 #if !defined(BOOST_ASIO_WINDOWS) && !defined(__CYGWIN__)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/descriptor_ops.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_work.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -44,15 +45,21 @@ class descriptor_read_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     descriptor_read_op_base* o(static_cast<descriptor_read_op_base*>(base));
 
     buffer_sequence_adapter<boost::asio::mutable_buffer,
         MutableBufferSequence> bufs(o->buffers_);
 
-    return descriptor_ops::non_blocking_read(o->descriptor_,
-        bufs.buffers(), bufs.count(), o->ec_, o->bytes_transferred_);
+    status result = descriptor_ops::non_blocking_read(o->descriptor_,
+        bufs.buffers(), bufs.count(), o->ec_, o->bytes_transferred_)
+      ? done : not_done;
+
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_read",
+          o->ec_, o->bytes_transferred_));
+
+    return result;
   }
 
 private:
@@ -73,17 +80,19 @@ class descriptor_read_op
         descriptor, buffers, &descriptor_read_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     descriptor_read_op* o(static_cast<descriptor_read_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -101,7 +110,7 @@ class descriptor_read_op
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/descriptor_write_op.hpp b/include/boost/asio/detail/descriptor_write_op.hpp
index f635feb122..0063491742 100644
--- a/include/boost/asio/detail/descriptor_write_op.hpp
+++ b/include/boost/asio/detail/descriptor_write_op.hpp
@@ -19,11 +19,12 @@
 
 #if !defined(BOOST_ASIO_WINDOWS) && !defined(__CYGWIN__)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/descriptor_ops.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_work.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -44,15 +45,21 @@ class descriptor_write_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     descriptor_write_op_base* o(static_cast<descriptor_write_op_base*>(base));
 
     buffer_sequence_adapter<boost::asio::const_buffer,
         ConstBufferSequence> bufs(o->buffers_);
 
-    return descriptor_ops::non_blocking_write(o->descriptor_,
-        bufs.buffers(), bufs.count(), o->ec_, o->bytes_transferred_);
+    status result = descriptor_ops::non_blocking_write(o->descriptor_,
+        bufs.buffers(), bufs.count(), o->ec_, o->bytes_transferred_)
+      ? done : not_done;
+
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_write",
+          o->ec_, o->bytes_transferred_));
+
+    return result;
   }
 
 private:
@@ -73,17 +80,19 @@ class descriptor_write_op
         descriptor, buffers, &descriptor_write_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     descriptor_write_op* o(static_cast<descriptor_write_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -101,7 +110,7 @@ class descriptor_write_op
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/dev_poll_reactor.hpp b/include/boost/asio/detail/dev_poll_reactor.hpp
index 17f57d5221..805f44b6ee 100644
--- a/include/boost/asio/detail/dev_poll_reactor.hpp
+++ b/include/boost/asio/detail/dev_poll_reactor.hpp
@@ -33,7 +33,7 @@
 #include <boost/asio/detail/timer_queue_base.hpp>
 #include <boost/asio/detail/timer_queue_set.hpp>
 #include <boost/asio/detail/wait_op.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/execution_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -42,7 +42,7 @@ namespace asio {
 namespace detail {
 
 class dev_poll_reactor
-  : public boost::asio::detail::service_base<dev_poll_reactor>
+  : public execution_context_service_base<dev_poll_reactor>
 {
 public:
   enum op_types { read_op = 0, write_op = 1,
@@ -54,17 +54,17 @@ class dev_poll_reactor
   };
 
   // Constructor.
-  BOOST_ASIO_DECL dev_poll_reactor(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL dev_poll_reactor(boost::asio::execution_context& ctx);
 
   // Destructor.
   BOOST_ASIO_DECL ~dev_poll_reactor();
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Recreate internal descriptors following a fork.
-  BOOST_ASIO_DECL void fork_service(
-      boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void notify_fork(
+      boost::asio::execution_context::fork_event fork_ev);
 
   // Initialise the task.
   BOOST_ASIO_DECL void init_task();
@@ -87,7 +87,7 @@ class dev_poll_reactor
   // Post a reactor operation for immediate completion.
   void post_immediate_completion(reactor_op* op, bool is_continuation)
   {
-    io_service_.post_immediate_completion(op, is_continuation);
+    scheduler_.post_immediate_completion(op, is_continuation);
   }
 
   // Start a new operation. The reactor operation will be performed when the
@@ -139,8 +139,14 @@ class dev_poll_reactor
       typename timer_queue<Time_Traits>::per_timer_data& timer,
       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
 
+  // Move the timer operations associated with the given timer.
+  template <typename Time_Traits>
+  void move_timer(timer_queue<Time_Traits>& queue,
+      typename timer_queue<Time_Traits>::per_timer_data& target,
+      typename timer_queue<Time_Traits>::per_timer_data& source);
+
   // Run /dev/poll once until interrupted or events are ready to be dispatched.
-  BOOST_ASIO_DECL void run(bool block, op_queue<operation>& ops);
+  BOOST_ASIO_DECL void run(long usec, op_queue<operation>& ops);
 
   // Interrupt the select loop.
   BOOST_ASIO_DECL void interrupt();
@@ -159,7 +165,7 @@ class dev_poll_reactor
   // Get the timeout value for the /dev/poll DP_POLL operation. The timeout
   // value is returned as a number of milliseconds. A return value of -1
   // indicates that the poll should block indefinitely.
-  BOOST_ASIO_DECL int get_timeout();
+  BOOST_ASIO_DECL int get_timeout(int msec);
 
   // Cancel all operations associated with the given descriptor. The do_cancel
   // function of the handler objects will be invoked. This function does not
@@ -170,8 +176,8 @@ class dev_poll_reactor
   // Add a pending event entry for the given descriptor.
   BOOST_ASIO_DECL ::pollfd& add_pending_event_change(int descriptor);
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_;
+  // The scheduler implementation used to post completions.
+  scheduler& scheduler_;
 
   // Mutex to protect access to internal data.
   boost::asio::detail::mutex mutex_;
diff --git a/include/boost/asio/detail/epoll_reactor.hpp b/include/boost/asio/detail/epoll_reactor.hpp
index 34ed0370f5..e1acb48da7 100644
--- a/include/boost/asio/detail/epoll_reactor.hpp
+++ b/include/boost/asio/detail/epoll_reactor.hpp
@@ -19,10 +19,9 @@
 
 #if defined(BOOST_ASIO_HAS_EPOLL)
 
-#include <boost/asio/io_service.hpp>
 #include <boost/asio/detail/atomic_count.hpp>
+#include <boost/asio/detail/conditionally_enabled_mutex.hpp>
 #include <boost/asio/detail/limits.hpp>
-#include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/object_pool.hpp>
 #include <boost/asio/detail/op_queue.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
@@ -31,6 +30,7 @@
 #include <boost/asio/detail/timer_queue_base.hpp>
 #include <boost/asio/detail/timer_queue_set.hpp>
 #include <boost/asio/detail/wait_op.hpp>
+#include <boost/asio/execution_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -39,8 +39,12 @@ namespace asio {
 namespace detail {
 
 class epoll_reactor
-  : public boost::asio::detail::service_base<epoll_reactor>
+  : public execution_context_service_base<epoll_reactor>
 {
+private:
+  // The mutex type used by this reactor.
+  typedef conditionally_enabled_mutex mutex;
+
 public:
   enum op_types { read_op = 0, write_op = 1,
     connect_op = 1, except_op = 2, max_ops = 3 };
@@ -59,14 +63,15 @@ class epoll_reactor
     int descriptor_;
     uint32_t registered_events_;
     op_queue<reactor_op> op_queue_[max_ops];
+    bool try_speculative_[max_ops];
     bool shutdown_;
 
-    BOOST_ASIO_DECL descriptor_state();
+    BOOST_ASIO_DECL descriptor_state(bool locking);
     void set_ready_events(uint32_t events) { task_result_ = events; }
     void add_ready_events(uint32_t events) { task_result_ |= events; }
     BOOST_ASIO_DECL operation* perform_io(uint32_t events);
     BOOST_ASIO_DECL static void do_complete(
-        io_service_impl* owner, operation* base,
+        void* owner, operation* base,
         const boost::system::error_code& ec, std::size_t bytes_transferred);
   };
 
@@ -74,17 +79,17 @@ class epoll_reactor
   typedef descriptor_state* per_descriptor_data;
 
   // Constructor.
-  BOOST_ASIO_DECL epoll_reactor(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL epoll_reactor(boost::asio::execution_context& ctx);
 
   // Destructor.
   BOOST_ASIO_DECL ~epoll_reactor();
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Recreate internal descriptors following a fork.
-  BOOST_ASIO_DECL void fork_service(
-      boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void notify_fork(
+      boost::asio::execution_context::fork_event fork_ev);
 
   // Initialise the task.
   BOOST_ASIO_DECL void init_task();
@@ -108,7 +113,7 @@ class epoll_reactor
   // Post a reactor operation for immediate completion.
   void post_immediate_completion(reactor_op* op, bool is_continuation)
   {
-    io_service_.post_immediate_completion(op, is_continuation);
+    scheduler_.post_immediate_completion(op, is_continuation);
   }
 
   // Start a new operation. The reactor operation will be performed when the
@@ -162,8 +167,14 @@ class epoll_reactor
       typename timer_queue<Time_Traits>::per_timer_data& timer,
       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
 
+  // Move the timer operations associated with the given timer.
+  template <typename Time_Traits>
+  void move_timer(timer_queue<Time_Traits>& queue,
+      typename timer_queue<Time_Traits>::per_timer_data& target,
+      typename timer_queue<Time_Traits>::per_timer_data& source);
+
   // Run epoll once until interrupted or events are ready to be dispatched.
-  BOOST_ASIO_DECL void run(bool block, op_queue<operation>& ops);
+  BOOST_ASIO_DECL void run(long usec, op_queue<operation>& ops);
 
   // Interrupt the select loop.
   BOOST_ASIO_DECL void interrupt();
@@ -197,7 +208,7 @@ class epoll_reactor
   // Get the timeout value for the epoll_wait call. The timeout value is
   // returned as a number of milliseconds. A return value of -1 indicates
   // that epoll_wait should block indefinitely.
-  BOOST_ASIO_DECL int get_timeout();
+  BOOST_ASIO_DECL int get_timeout(int msec);
 
 #if defined(BOOST_ASIO_HAS_TIMERFD)
   // Get the timeout value for the timer descriptor. The return value is the
@@ -205,8 +216,8 @@ class epoll_reactor
   BOOST_ASIO_DECL int get_timeout(itimerspec& ts);
 #endif // defined(BOOST_ASIO_HAS_TIMERFD)
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_;
+  // The scheduler implementation used to post completions.
+  scheduler& scheduler_;
 
   // Mutex to protect access to internal data.
   mutex mutex_;
diff --git a/include/boost/asio/detail/executor_op.hpp b/include/boost/asio/detail/executor_op.hpp
new file mode 100644
index 0000000000..f3364f5155
--- /dev/null
+++ b/include/boost/asio/detail/executor_op.hpp
@@ -0,0 +1,86 @@
+//
+// detail/executor_op.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_EXECUTOR_OP_HPP
+#define BOOST_ASIO_DETAIL_EXECUTOR_OP_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/scheduler_operation.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Handler, typename Alloc,
+    typename Operation = scheduler_operation>
+class executor_op : public Operation
+{
+public:
+  BOOST_ASIO_DEFINE_HANDLER_ALLOCATOR_PTR(executor_op);
+
+  template <typename H>
+  executor_op(BOOST_ASIO_MOVE_ARG(H) h, const Alloc& allocator)
+    : Operation(&executor_op::do_complete),
+      handler_(BOOST_ASIO_MOVE_CAST(H)(h)),
+      allocator_(allocator)
+  {
+  }
+
+  static void do_complete(void* owner, Operation* base,
+      const boost::system::error_code& /*ec*/,
+      std::size_t /*bytes_transferred*/)
+  {
+    // Take ownership of the handler object.
+    executor_op* o(static_cast<executor_op*>(base));
+    Alloc allocator(o->allocator_);
+    ptr p = { detail::addressof(allocator), o, o };
+
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
+
+    // Make a copy of the handler so that the memory can be deallocated before
+    // the upcall is made. Even if we're not about to make an upcall, a
+    // sub-object of the handler may be the true owner of the memory associated
+    // with the handler. Consequently, a local copy of the handler is required
+    // to ensure that any owning sub-object remains valid until after we have
+    // deallocated the memory here.
+    Handler handler(BOOST_ASIO_MOVE_CAST(Handler)(o->handler_));
+    p.reset();
+
+    // Make the upcall if required.
+    if (owner)
+    {
+      fenced_block b(fenced_block::half);
+      BOOST_ASIO_HANDLER_INVOCATION_BEGIN(());
+      boost_asio_handler_invoke_helpers::invoke(handler, handler);
+      BOOST_ASIO_HANDLER_INVOCATION_END;
+    }
+  }
+
+private:
+  Handler handler_;
+  Alloc allocator_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_EXECUTOR_OP_HPP
diff --git a/include/boost/asio/detail/function.hpp b/include/boost/asio/detail/functional.hpp
similarity index 69%
rename from include/boost/asio/detail/function.hpp
rename to include/boost/asio/detail/functional.hpp
index db26144c5f..a7d6064e4a 100644
--- a/include/boost/asio/detail/function.hpp
+++ b/include/boost/asio/detail/functional.hpp
@@ -1,6 +1,6 @@
 //
-// detail/function.hpp
-// ~~~~~~~~~~~~~~~~~~~
+// detail/functional.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_FUNCTION_HPP
-#define BOOST_ASIO_DETAIL_FUNCTION_HPP
+#ifndef BOOST_ASIO_DETAIL_FUNCTIONAL_HPP
+#define BOOST_ASIO_DETAIL_FUNCTIONAL_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -17,11 +17,11 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_HAS_STD_FUNCTION)
-# include <functional>
-#else // defined(BOOST_ASIO_HAS_STD_FUNCTION)
+#include <functional>
+
+#if !defined(BOOST_ASIO_HAS_STD_FUNCTION)
 # include <boost/function.hpp>
-#endif // defined(BOOST_ASIO_HAS_STD_FUNCTION)
+#endif // !defined(BOOST_ASIO_HAS_STD_FUNCTION)
 
 namespace boost {
 namespace asio {
@@ -37,4 +37,4 @@ using boost::function;
 } // namespace asio
 } // namespace boost
 
-#endif // BOOST_ASIO_DETAIL_FUNCTION_HPP
+#endif // BOOST_ASIO_DETAIL_FUNCTIONAL_HPP
diff --git a/include/boost/asio/detail/gcc_arm_fenced_block.hpp b/include/boost/asio/detail/gcc_arm_fenced_block.hpp
index b4805c35cd..51a8ca7c55 100644
--- a/include/boost/asio/detail/gcc_arm_fenced_block.hpp
+++ b/include/boost/asio/detail/gcc_arm_fenced_block.hpp
@@ -19,6 +19,8 @@
 
 #if defined(__GNUC__) && defined(__arm__)
 
+#include <boost/asio/detail/noncopyable.hpp>
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
diff --git a/include/boost/asio/detail/gcc_hppa_fenced_block.hpp b/include/boost/asio/detail/gcc_hppa_fenced_block.hpp
index b9aa9e2ca4..95f47ac8eb 100644
--- a/include/boost/asio/detail/gcc_hppa_fenced_block.hpp
+++ b/include/boost/asio/detail/gcc_hppa_fenced_block.hpp
@@ -19,6 +19,8 @@
 
 #if defined(__GNUC__) && (defined(__hppa) || defined(__hppa__))
 
+#include <boost/asio/detail/noncopyable.hpp>
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
diff --git a/include/boost/asio/detail/gcc_sync_fenced_block.hpp b/include/boost/asio/detail/gcc_sync_fenced_block.hpp
index e8e6c54643..b9026b1206 100644
--- a/include/boost/asio/detail/gcc_sync_fenced_block.hpp
+++ b/include/boost/asio/detail/gcc_sync_fenced_block.hpp
@@ -22,6 +22,8 @@
   && !defined(__INTEL_COMPILER) && !defined(__ICL) \
   && !defined(__ICC) && !defined(__ECC) && !defined(__PATHSCALE__)
 
+#include <boost/asio/detail/noncopyable.hpp>
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
diff --git a/include/boost/asio/detail/gcc_x86_fenced_block.hpp b/include/boost/asio/detail/gcc_x86_fenced_block.hpp
index fe0ce8a316..be355a115a 100644
--- a/include/boost/asio/detail/gcc_x86_fenced_block.hpp
+++ b/include/boost/asio/detail/gcc_x86_fenced_block.hpp
@@ -19,6 +19,8 @@
 
 #if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
 
+#include <boost/asio/detail/noncopyable.hpp>
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
diff --git a/include/boost/asio/detail/global.hpp b/include/boost/asio/detail/global.hpp
new file mode 100644
index 0000000000..581478909f
--- /dev/null
+++ b/include/boost/asio/detail/global.hpp
@@ -0,0 +1,54 @@
+//
+// detail/global.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_GLOBAL_HPP
+#define BOOST_ASIO_DETAIL_GLOBAL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if !defined(BOOST_ASIO_HAS_THREADS)
+# include <boost/asio/detail/null_global.hpp>
+#elif defined(BOOST_ASIO_WINDOWS)
+# include <boost/asio/detail/win_global.hpp>
+#elif defined(BOOST_ASIO_HAS_PTHREADS)
+# include <boost/asio/detail/posix_global.hpp>
+#elif defined(BOOST_ASIO_HAS_STD_CALL_ONCE)
+# include <boost/asio/detail/std_global.hpp>
+#else
+# error Only Windows, POSIX and std::call_once are supported!
+#endif
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T>
+inline T& global()
+{
+#if !defined(BOOST_ASIO_HAS_THREADS)
+  return null_global<T>();
+#elif defined(BOOST_ASIO_WINDOWS)
+  return win_global<T>();
+#elif defined(BOOST_ASIO_HAS_PTHREADS)
+  return posix_global<T>();
+#elif defined(BOOST_ASIO_HAS_STD_CALL_ONCE)
+  return std_global<T>();
+#endif
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#endif // BOOST_ASIO_DETAIL_GLOBAL_HPP
diff --git a/include/boost/asio/detail/handler_alloc_helpers.hpp b/include/boost/asio/detail/handler_alloc_helpers.hpp
index a03cb41976..ee2e80c81d 100644
--- a/include/boost/asio/detail/handler_alloc_helpers.hpp
+++ b/include/boost/asio/detail/handler_alloc_helpers.hpp
@@ -16,8 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/recycling_allocator.hpp>
+#include <boost/asio/associated_allocator.hpp>
 #include <boost/asio/handler_alloc_hook.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -51,16 +53,165 @@ inline void deallocate(void* p, std::size_t s, Handler& h)
 
 } // namespace boost_asio_handler_alloc_helpers
 
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Handler, typename T>
+class hook_allocator
+{
+public:
+  typedef T value_type;
+
+  template <typename U>
+  struct rebind
+  {
+    typedef hook_allocator<Handler, U> other;
+  };
+
+  explicit hook_allocator(Handler& h)
+    : handler_(h)
+  {
+  }
+
+  template <typename U>
+  hook_allocator(const hook_allocator<Handler, U>& a)
+    : handler_(a.handler_)
+  {
+  }
+
+  T* allocate(std::size_t n)
+  {
+    return static_cast<T*>(
+        boost_asio_handler_alloc_helpers::allocate(sizeof(T) * n, handler_));
+  }
+
+  void deallocate(T* p, std::size_t n)
+  {
+    boost_asio_handler_alloc_helpers::deallocate(p, sizeof(T) * n, handler_);
+  }
+
+//private:
+  Handler& handler_;
+};
+
+template <typename Handler>
+class hook_allocator<Handler, void>
+{
+public:
+  typedef void value_type;
+
+  template <typename U>
+  struct rebind
+  {
+    typedef hook_allocator<Handler, U> other;
+  };
+
+  explicit hook_allocator(Handler& h)
+    : handler_(h)
+  {
+  }
+
+  template <typename U>
+  hook_allocator(const hook_allocator<Handler, U>& a)
+    : handler_(a.handler_)
+  {
+  }
+
+//private:
+  Handler& handler_;
+};
+
+template <typename Handler, typename Allocator>
+struct get_hook_allocator
+{
+  typedef Allocator type;
+
+  static type get(Handler&, const Allocator& a)
+  {
+    return a;
+  }
+};
+
+template <typename Handler, typename T>
+struct get_hook_allocator<Handler, std::allocator<T> >
+{
+  typedef hook_allocator<Handler, T> type;
+
+  static type get(Handler& handler, const std::allocator<T>&)
+  {
+    return type(handler);
+  }
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
 #define BOOST_ASIO_DEFINE_HANDLER_PTR(op) \
   struct ptr \
   { \
     Handler* h; \
+    op* v; \
+    op* p; \
+    ~ptr() \
+    { \
+      reset(); \
+    } \
+    static op* allocate(Handler& handler) \
+    { \
+      typedef typename ::boost::asio::associated_allocator< \
+        Handler>::type associated_allocator_type; \
+      typedef typename ::boost::asio::detail::get_hook_allocator< \
+        Handler, associated_allocator_type>::type hook_allocator_type; \
+      BOOST_ASIO_REBIND_ALLOC(hook_allocator_type, op) a( \
+            ::boost::asio::detail::get_hook_allocator< \
+              Handler, associated_allocator_type>::get( \
+                handler, ::boost::asio::get_associated_allocator(handler))); \
+      return a.allocate(1); \
+    } \
+    void reset() \
+    { \
+      if (p) \
+      { \
+        p->~op(); \
+        p = 0; \
+      } \
+      if (v) \
+      { \
+        typedef typename ::boost::asio::associated_allocator< \
+          Handler>::type associated_allocator_type; \
+        typedef typename ::boost::asio::detail::get_hook_allocator< \
+          Handler, associated_allocator_type>::type hook_allocator_type; \
+        BOOST_ASIO_REBIND_ALLOC(hook_allocator_type, op) a( \
+              ::boost::asio::detail::get_hook_allocator< \
+                Handler, associated_allocator_type>::get( \
+                  *h, ::boost::asio::get_associated_allocator(*h))); \
+        a.deallocate(static_cast<op*>(v), 1); \
+        v = 0; \
+      } \
+    } \
+  } \
+  /**/
+
+#define BOOST_ASIO_DEFINE_HANDLER_ALLOCATOR_PTR(op) \
+  struct ptr \
+  { \
+    const Alloc* a; \
     void* v; \
     op* p; \
     ~ptr() \
     { \
       reset(); \
     } \
+    static op* allocate(const Alloc& a) \
+    { \
+      typedef typename ::boost::asio::detail::get_recycling_allocator< \
+        Alloc>::type recycling_allocator_type; \
+      BOOST_ASIO_REBIND_ALLOC(recycling_allocator_type, op) a1( \
+            ::boost::asio::detail::get_recycling_allocator<Alloc>::get(a)); \
+      return a1.allocate(1); \
+    } \
     void reset() \
     { \
       if (p) \
@@ -70,7 +221,11 @@ inline void deallocate(void* p, std::size_t s, Handler& h)
       } \
       if (v) \
       { \
-        boost_asio_handler_alloc_helpers::deallocate(v, sizeof(op), *h); \
+        typedef typename ::boost::asio::detail::get_recycling_allocator< \
+          Alloc>::type recycling_allocator_type; \
+        BOOST_ASIO_REBIND_ALLOC(recycling_allocator_type, op) a1( \
+              ::boost::asio::detail::get_recycling_allocator<Alloc>::get(*a)); \
+        a1.deallocate(static_cast<op*>(v), 1); \
         v = 0; \
       } \
     } \
diff --git a/include/boost/asio/detail/handler_cont_helpers.hpp b/include/boost/asio/detail/handler_cont_helpers.hpp
index 9a361a9ca4..a47ecf2d4a 100644
--- a/include/boost/asio/detail/handler_cont_helpers.hpp
+++ b/include/boost/asio/detail/handler_cont_helpers.hpp
@@ -16,7 +16,7 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/handler_continuation_hook.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
diff --git a/include/boost/asio/detail/handler_invoke_helpers.hpp b/include/boost/asio/detail/handler_invoke_helpers.hpp
index 43f74f3272..290ecb194f 100644
--- a/include/boost/asio/detail/handler_invoke_helpers.hpp
+++ b/include/boost/asio/detail/handler_invoke_helpers.hpp
@@ -16,7 +16,7 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
diff --git a/include/boost/asio/detail/handler_tracking.hpp b/include/boost/asio/detail/handler_tracking.hpp
index fd69bdd5b6..92e8a469f1 100644
--- a/include/boost/asio/detail/handler_tracking.hpp
+++ b/include/boost/asio/detail/handler_tracking.hpp
@@ -17,7 +17,17 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+namespace boost {
+namespace asio {
+
+class execution_context;
+
+} // namespace asio
+} // namespace boost
+
+#if defined(BOOST_ASIO_CUSTOM_HANDLER_TRACKING)
+# include BOOST_ASIO_CUSTOM_HANDLER_TRACKING
+#elif defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
 # include <boost/system/error_code.hpp>
 # include <boost/asio/detail/cstdint.hpp>
 # include <boost/asio/detail/static_mutex.hpp>
@@ -30,7 +40,30 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-#if defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+#if defined(BOOST_ASIO_CUSTOM_HANDLER_TRACKING)
+
+// The user-specified header must define the following macros:
+// - BOOST_ASIO_INHERIT_TRACKED_HANDLER
+// - BOOST_ASIO_ALSO_INHERIT_TRACKED_HANDLER
+// - BOOST_ASIO_HANDLER_TRACKING_INIT
+// - BOOST_ASIO_HANDLER_CREATION(args)
+// - BOOST_ASIO_HANDLER_COMPLETION(args)
+// - BOOST_ASIO_HANDLER_INVOCATION_BEGIN(args)
+// - BOOST_ASIO_HANDLER_INVOCATION_END
+// - BOOST_ASIO_HANDLER_OPERATION(args)
+// - BOOST_ASIO_HANDLER_REACTOR_REGISTRATION(args)
+// - BOOST_ASIO_HANDLER_REACTOR_DEREGISTRATION(args)
+// - BOOST_ASIO_HANDLER_REACTOR_READ_EVENT
+// - BOOST_ASIO_HANDLER_REACTOR_WRITE_EVENT
+// - BOOST_ASIO_HANDLER_REACTOR_ERROR_EVENT
+// - BOOST_ASIO_HANDLER_REACTOR_EVENTS(args)
+// - BOOST_ASIO_HANDLER_REACTOR_OPERATION(args)
+
+# if !defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+#  define BOOST_ASIO_ENABLE_HANDLER_TRACKING 1
+# endif /// !defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+
+#elif defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
 
 class handler_tracking
 {
@@ -58,14 +91,16 @@ class handler_tracking
   BOOST_ASIO_DECL static void init();
 
   // Record the creation of a tracked handler.
-  BOOST_ASIO_DECL static void creation(tracked_handler* h,
-      const char* object_type, void* object, const char* op_name);
+  BOOST_ASIO_DECL static void creation(
+      execution_context& context, tracked_handler& h,
+      const char* object_type, void* object,
+      uintmax_t native_handle, const char* op_name);
 
   class completion
   {
   public:
     // Constructor records that handler is to be invoked with no arguments.
-    BOOST_ASIO_DECL explicit completion(tracked_handler* h);
+    BOOST_ASIO_DECL explicit completion(const tracked_handler& h);
 
     // Destructor records only when an exception is thrown from the handler, or
     // if the memory is being freed without the handler having been invoked.
@@ -99,9 +134,32 @@ class handler_tracking
     completion* next_;
   };
 
-  // Record an operation that affects pending handlers.
-  BOOST_ASIO_DECL static void operation(const char* object_type,
-      void* object, const char* op_name);
+  // Record an operation that is not directly associated with a handler.
+  BOOST_ASIO_DECL static void operation(execution_context& context,
+      const char* object_type, void* object,
+      uintmax_t native_handle, const char* op_name);
+
+  // Record that a descriptor has been registered with the reactor.
+  BOOST_ASIO_DECL static void reactor_registration(execution_context& context,
+      uintmax_t native_handle, uintmax_t registration);
+
+  // Record that a descriptor has been deregistered from the reactor.
+  BOOST_ASIO_DECL static void reactor_deregistration(execution_context& context,
+      uintmax_t native_handle, uintmax_t registration);
+
+  // Record a reactor-based operation that is associated with a handler.
+  BOOST_ASIO_DECL static void reactor_events(execution_context& context,
+      uintmax_t registration, unsigned events);
+
+  // Record a reactor-based operation that is associated with a handler.
+  BOOST_ASIO_DECL static void reactor_operation(
+      const tracked_handler& h, const char* op_name,
+      const boost::system::error_code& ec);
+
+  // Record a reactor-based operation that is associated with a handler.
+  BOOST_ASIO_DECL static void reactor_operation(
+      const tracked_handler& h, const char* op_name,
+      const boost::system::error_code& ec, std::size_t bytes_transferred);
 
   // Write a line of output.
   BOOST_ASIO_DECL static void write_line(const char* format, ...);
@@ -135,6 +193,22 @@ class handler_tracking
 # define BOOST_ASIO_HANDLER_OPERATION(args) \
   boost::asio::detail::handler_tracking::operation args
 
+# define BOOST_ASIO_HANDLER_REACTOR_REGISTRATION(args) \
+  boost::asio::detail::handler_tracking::reactor_registration args
+
+# define BOOST_ASIO_HANDLER_REACTOR_DEREGISTRATION(args) \
+  boost::asio::detail::handler_tracking::reactor_deregistration args
+
+# define BOOST_ASIO_HANDLER_REACTOR_READ_EVENT 1
+# define BOOST_ASIO_HANDLER_REACTOR_WRITE_EVENT 2
+# define BOOST_ASIO_HANDLER_REACTOR_ERROR_EVENT 4
+
+# define BOOST_ASIO_HANDLER_REACTOR_EVENTS(args) \
+  boost::asio::detail::handler_tracking::reactor_events args
+
+# define BOOST_ASIO_HANDLER_REACTOR_OPERATION(args) \
+  boost::asio::detail::handler_tracking::reactor_operation args
+
 #else // defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
 
 # define BOOST_ASIO_INHERIT_TRACKED_HANDLER
@@ -145,6 +219,13 @@ class handler_tracking
 # define BOOST_ASIO_HANDLER_INVOCATION_BEGIN(args) (void)0
 # define BOOST_ASIO_HANDLER_INVOCATION_END (void)0
 # define BOOST_ASIO_HANDLER_OPERATION(args) (void)0
+# define BOOST_ASIO_HANDLER_REACTOR_REGISTRATION(args) (void)0
+# define BOOST_ASIO_HANDLER_REACTOR_DEREGISTRATION(args) (void)0
+# define BOOST_ASIO_HANDLER_REACTOR_READ_EVENT 0
+# define BOOST_ASIO_HANDLER_REACTOR_WRITE_EVENT 0
+# define BOOST_ASIO_HANDLER_REACTOR_ERROR_EVENT 0
+# define BOOST_ASIO_HANDLER_REACTOR_EVENTS(args) (void)0
+# define BOOST_ASIO_HANDLER_REACTOR_OPERATION(args) (void)0
 
 #endif // defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
 
diff --git a/include/boost/asio/detail/handler_type_requirements.hpp b/include/boost/asio/detail/handler_type_requirements.hpp
index bc2fbce0ce..580128d657 100644
--- a/include/boost/asio/detail/handler_type_requirements.hpp
+++ b/include/boost/asio/detail/handler_type_requirements.hpp
@@ -50,7 +50,7 @@
 #endif // !defined(BOOST_ASIO_DISABLE_HANDLER_TYPE_REQUIREMENTS)
 
 #if defined(BOOST_ASIO_ENABLE_HANDLER_TYPE_REQUIREMENTS)
-# include <boost/asio/handler_type.hpp>
+# include <boost/asio/async_result.hpp>
 #endif // defined(BOOST_ASIO_ENABLE_HANDLER_TYPE_REQUIREMENTS)
 
 namespace boost {
@@ -62,19 +62,19 @@ namespace detail {
 # if defined(BOOST_ASIO_ENABLE_HANDLER_TYPE_REQUIREMENTS_ASSERT)
 
 template <typename Handler>
-auto zero_arg_handler_test(Handler h, void*)
+auto zero_arg_copyable_handler_test(Handler h, void*)
   -> decltype(
     sizeof(Handler(static_cast<const Handler&>(h))),
     ((h)()),
     char(0));
 
 template <typename Handler>
-char (&zero_arg_handler_test(Handler, ...))[2];
+char (&zero_arg_copyable_handler_test(Handler, ...))[2];
 
 template <typename Handler, typename Arg1>
 auto one_arg_handler_test(Handler h, Arg1* a1)
   -> decltype(
-    sizeof(Handler(static_cast<const Handler&>(h))),
+    sizeof(Handler(BOOST_ASIO_MOVE_CAST(Handler)(h))),
     ((h)(*a1)),
     char(0));
 
@@ -84,13 +84,23 @@ char (&one_arg_handler_test(Handler h, ...))[2];
 template <typename Handler, typename Arg1, typename Arg2>
 auto two_arg_handler_test(Handler h, Arg1* a1, Arg2* a2)
   -> decltype(
-    sizeof(Handler(static_cast<const Handler&>(h))),
+    sizeof(Handler(BOOST_ASIO_MOVE_CAST(Handler)(h))),
     ((h)(*a1, *a2)),
     char(0));
 
 template <typename Handler>
 char (&two_arg_handler_test(Handler, ...))[2];
 
+template <typename Handler, typename Arg1, typename Arg2>
+auto two_arg_move_handler_test(Handler h, Arg1* a1, Arg2* a2)
+  -> decltype(
+    sizeof(Handler(BOOST_ASIO_MOVE_CAST(Handler)(h))),
+    ((h)(*a1, BOOST_ASIO_MOVE_CAST(Arg2)(*a2))),
+    char(0));
+
+template <typename Handler>
+char (&two_arg_move_handler_test(Handler, ...))[2];
+
 #  define BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT(expr, msg) \
      static_assert(expr, msg);
 
@@ -104,6 +114,13 @@ template <typename T> T& lvref();
 template <typename T> T& lvref(T);
 template <typename T> const T& clvref();
 template <typename T> const T& clvref(T);
+#if defined(BOOST_ASIO_HAS_MOVE)
+template <typename T> T rvref();
+template <typename T> T rvref(T);
+#else // defined(BOOST_ASIO_HAS_MOVE)
+template <typename T> const T& rvref();
+template <typename T> const T& rvref(T);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 template <typename T> char argbyv(T);
 
 template <int>
@@ -118,7 +135,7 @@ struct handler_type_requirements
       void()) asio_true_handler_type; \
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
-      sizeof(boost::asio::detail::zero_arg_handler_test( \
+      sizeof(boost::asio::detail::zero_arg_copyable_handler_test( \
           boost::asio::detail::clvref< \
             asio_true_handler_type>(), 0)) == 1, \
       "CompletionHandler type requirements not met") \
@@ -142,7 +159,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::two_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0), \
           static_cast<const std::size_t*>(0))) == 1, \
@@ -151,7 +168,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -160,7 +177,6 @@ struct handler_type_requirements
             boost::asio::detail::lvref<const std::size_t>()), \
         char(0))> BOOST_ASIO_UNUSED_TYPEDEF
 
-
 #define BOOST_ASIO_WRITE_HANDLER_CHECK( \
     handler_type, handler) \
   \
@@ -170,7 +186,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::two_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0), \
           static_cast<const std::size_t*>(0))) == 1, \
@@ -179,7 +195,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -197,7 +213,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::one_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0))) == 1, \
       "AcceptHandler type requirements not met") \
@@ -205,7 +221,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -213,6 +229,33 @@ struct handler_type_requirements
             boost::asio::detail::lvref<const boost::system::error_code>()), \
         char(0))> BOOST_ASIO_UNUSED_TYPEDEF
 
+#define BOOST_ASIO_MOVE_ACCEPT_HANDLER_CHECK( \
+    handler_type, handler, socket_type) \
+  \
+  typedef BOOST_ASIO_HANDLER_TYPE(handler_type, \
+      void(boost::system::error_code, socket_type)) \
+    asio_true_handler_type; \
+  \
+  BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
+      sizeof(boost::asio::detail::two_arg_move_handler_test( \
+          boost::asio::detail::rvref< \
+            asio_true_handler_type>(), \
+          static_cast<const boost::system::error_code*>(0), \
+          static_cast<socket_type*>(0))) == 1, \
+      "MoveAcceptHandler type requirements not met") \
+  \
+  typedef boost::asio::detail::handler_type_requirements< \
+      sizeof( \
+        boost::asio::detail::argbyv( \
+          boost::asio::detail::rvref< \
+            asio_true_handler_type>())) + \
+      sizeof( \
+        boost::asio::detail::lvref< \
+          asio_true_handler_type>()( \
+            boost::asio::detail::lvref<const boost::system::error_code>(), \
+            boost::asio::detail::rvref<socket_type>()), \
+        char(0))> BOOST_ASIO_UNUSED_TYPEDEF
+
 #define BOOST_ASIO_CONNECT_HANDLER_CHECK( \
     handler_type, handler) \
   \
@@ -222,7 +265,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::one_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0))) == 1, \
       "ConnectHandler type requirements not met") \
@@ -230,7 +273,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -238,7 +281,34 @@ struct handler_type_requirements
             boost::asio::detail::lvref<const boost::system::error_code>()), \
         char(0))> BOOST_ASIO_UNUSED_TYPEDEF
 
-#define BOOST_ASIO_COMPOSED_CONNECT_HANDLER_CHECK( \
+#define BOOST_ASIO_RANGE_CONNECT_HANDLER_CHECK( \
+    handler_type, handler, endpoint_type) \
+  \
+  typedef BOOST_ASIO_HANDLER_TYPE(handler_type, \
+      void(boost::system::error_code, endpoint_type)) \
+    asio_true_handler_type; \
+  \
+  BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
+      sizeof(boost::asio::detail::two_arg_handler_test( \
+          boost::asio::detail::rvref< \
+            asio_true_handler_type>(), \
+          static_cast<const boost::system::error_code*>(0), \
+          static_cast<const endpoint_type*>(0))) == 1, \
+      "RangeConnectHandler type requirements not met") \
+  \
+  typedef boost::asio::detail::handler_type_requirements< \
+      sizeof( \
+        boost::asio::detail::argbyv( \
+          boost::asio::detail::rvref< \
+            asio_true_handler_type>())) + \
+      sizeof( \
+        boost::asio::detail::lvref< \
+          asio_true_handler_type>()( \
+            boost::asio::detail::lvref<const boost::system::error_code>(), \
+            boost::asio::detail::lvref<const endpoint_type>()), \
+        char(0))> BOOST_ASIO_UNUSED_TYPEDEF
+
+#define BOOST_ASIO_ITERATOR_CONNECT_HANDLER_CHECK( \
     handler_type, handler, iter_type) \
   \
   typedef BOOST_ASIO_HANDLER_TYPE(handler_type, \
@@ -247,16 +317,16 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::two_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0), \
           static_cast<const iter_type*>(0))) == 1, \
-      "ComposedConnectHandler type requirements not met") \
+      "IteratorConnectHandler type requirements not met") \
   \
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -266,30 +336,30 @@ struct handler_type_requirements
         char(0))> BOOST_ASIO_UNUSED_TYPEDEF
 
 #define BOOST_ASIO_RESOLVE_HANDLER_CHECK( \
-    handler_type, handler, iter_type) \
+    handler_type, handler, range_type) \
   \
   typedef BOOST_ASIO_HANDLER_TYPE(handler_type, \
-      void(boost::system::error_code, iter_type)) \
+      void(boost::system::error_code, range_type)) \
     asio_true_handler_type; \
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::two_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0), \
-          static_cast<const iter_type*>(0))) == 1, \
+          static_cast<const range_type*>(0))) == 1, \
       "ResolveHandler type requirements not met") \
   \
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
           asio_true_handler_type>()( \
             boost::asio::detail::lvref<const boost::system::error_code>(), \
-            boost::asio::detail::lvref<const iter_type>()), \
+            boost::asio::detail::lvref<const range_type>()), \
         char(0))> BOOST_ASIO_UNUSED_TYPEDEF
 
 #define BOOST_ASIO_WAIT_HANDLER_CHECK( \
@@ -301,7 +371,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::one_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0))) == 1, \
       "WaitHandler type requirements not met") \
@@ -309,7 +379,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -326,7 +396,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::two_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0), \
           static_cast<const int*>(0))) == 1, \
@@ -335,7 +405,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -353,7 +423,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::one_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0))) == 1, \
       "HandshakeHandler type requirements not met") \
@@ -361,7 +431,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -378,7 +448,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::two_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0), \
           static_cast<const std::size_t*>(0))) == 1, \
@@ -387,7 +457,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -405,7 +475,7 @@ struct handler_type_requirements
   \
   BOOST_ASIO_HANDLER_TYPE_REQUIREMENTS_ASSERT( \
       sizeof(boost::asio::detail::one_arg_handler_test( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>(), \
           static_cast<const boost::system::error_code*>(0))) == 1, \
       "ShutdownHandler type requirements not met") \
@@ -413,7 +483,7 @@ struct handler_type_requirements
   typedef boost::asio::detail::handler_type_requirements< \
       sizeof( \
         boost::asio::detail::argbyv( \
-          boost::asio::detail::clvref< \
+          boost::asio::detail::rvref< \
             asio_true_handler_type>())) + \
       sizeof( \
         boost::asio::detail::lvref< \
@@ -443,7 +513,11 @@ struct handler_type_requirements
     handler_type, handler) \
   typedef int BOOST_ASIO_UNUSED_TYPEDEF
 
-#define BOOST_ASIO_COMPOSED_CONNECT_HANDLER_CHECK( \
+#define BOOST_ASIO_RANGE_CONNECT_HANDLER_CHECK( \
+    handler_type, handler, iter_type) \
+  typedef int BOOST_ASIO_UNUSED_TYPEDEF
+
+#define BOOST_ASIO_ITERATOR_CONNECT_HANDLER_CHECK( \
     handler_type, handler, iter_type) \
   typedef int BOOST_ASIO_UNUSED_TYPEDEF
 
diff --git a/include/boost/asio/detail/handler_work.hpp b/include/boost/asio/detail/handler_work.hpp
new file mode 100644
index 0000000000..62fbe68e46
--- /dev/null
+++ b/include/boost/asio/detail/handler_work.hpp
@@ -0,0 +1,97 @@
+//
+// detail/handler_work.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_HANDLER_WORK_HPP
+#define BOOST_ASIO_DETAIL_HANDLER_WORK_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+// A helper class template to allow completion handlers to be dispatched
+// through either the new executors framework or the old invocaton hook. The
+// primary template uses the new executors framework.
+template <typename Handler, typename Executor
+    = typename associated_executor<Handler>::type>
+class handler_work
+{
+public:
+  explicit handler_work(Handler& handler) BOOST_ASIO_NOEXCEPT
+    : executor_(associated_executor<Handler>::get(handler))
+  {
+  }
+
+  static void start(Handler& handler) BOOST_ASIO_NOEXCEPT
+  {
+    Executor ex(associated_executor<Handler>::get(handler));
+    ex.on_work_started();
+  }
+
+  ~handler_work()
+  {
+    executor_.on_work_finished();
+  }
+
+  template <typename Function>
+  void complete(Function& function, Handler& handler)
+  {
+    executor_.dispatch(BOOST_ASIO_MOVE_CAST(Function)(function),
+        associated_allocator<Handler>::get(handler));
+  }
+
+private:
+  // Disallow copying and assignment.
+  handler_work(const handler_work&);
+  handler_work& operator=(const handler_work&);
+
+  typename associated_executor<Handler>::type executor_;
+};
+
+// This specialisation dispatches a handler through the old invocation hook.
+// The specialisation is not strictly required for correctness, as the
+// system_executor will dispatch through the hook anyway. However, by doing
+// this we avoid an extra copy of the handler.
+template <typename Handler>
+class handler_work<Handler, system_executor>
+{
+public:
+  explicit handler_work(Handler&) BOOST_ASIO_NOEXCEPT {}
+  static void start(Handler&) BOOST_ASIO_NOEXCEPT {}
+  ~handler_work() {}
+
+  template <typename Function>
+  void complete(Function& function, Handler& handler)
+  {
+    boost_asio_handler_invoke_helpers::invoke(function, handler);
+  }
+
+private:
+  // Disallow copying and assignment.
+  handler_work(const handler_work&);
+  handler_work& operator=(const handler_work&);
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_HANDLER_WORK_HPP
diff --git a/include/boost/asio/detail/impl/buffer_sequence_adapter.ipp b/include/boost/asio/detail/impl/buffer_sequence_adapter.ipp
index f471863e1a..c2114ba1cf 100644
--- a/include/boost/asio/detail/impl/buffer_sequence_adapter.ipp
+++ b/include/boost/asio/detail/impl/buffer_sequence_adapter.ipp
@@ -40,16 +40,16 @@ class winrt_buffer_impl :
 public:
   explicit winrt_buffer_impl(const boost::asio::const_buffer& b)
   {
-    bytes_ = const_cast<byte*>(boost::asio::buffer_cast<const byte*>(b));
-    length_ = boost::asio::buffer_size(b);
-    capacity_ = boost::asio::buffer_size(b);
+    bytes_ = const_cast<byte*>(static_cast<const byte*>(b.data()));
+    length_ = b.size();
+    capacity_ = b.size();
   }
 
   explicit winrt_buffer_impl(const boost::asio::mutable_buffer& b)
   {
-    bytes_ = const_cast<byte*>(boost::asio::buffer_cast<const byte*>(b));
+    bytes_ = static_cast<byte*>(b.data());
     length_ = 0;
-    capacity_ = boost::asio::buffer_size(b);
+    capacity_ = b.size();
   }
 
   ~winrt_buffer_impl()
diff --git a/include/boost/asio/detail/impl/descriptor_ops.ipp b/include/boost/asio/detail/impl/descriptor_ops.ipp
index 00f6b4796e..cdf5022306 100644
--- a/include/boost/asio/detail/impl/descriptor_ops.ipp
+++ b/include/boost/asio/detail/impl/descriptor_ops.ipp
@@ -439,6 +439,29 @@ int poll_write(int d, state_type state, boost::system::error_code& ec)
   return result;
 }
 
+int poll_error(int d, state_type state, boost::system::error_code& ec)
+{
+  if (d == -1)
+  {
+    ec = boost::asio::error::bad_descriptor;
+    return -1;
+  }
+
+  pollfd fds;
+  fds.fd = d;
+  fds.events = POLLPRI | POLLERR | POLLHUP;
+  fds.revents = 0;
+  int timeout = (state & user_set_non_blocking) ? 0 : -1;
+  errno = 0;
+  int result = error_wrapper(::poll(&fds, 1, timeout), ec);
+  if (result == 0)
+    ec = (state & user_set_non_blocking)
+      ? boost::asio::error::would_block : boost::system::error_code();
+  else if (result > 0)
+    ec = boost::system::error_code();
+  return result;
+}
+
 } // namespace descriptor_ops
 } // namespace detail
 } // namespace asio
diff --git a/include/boost/asio/detail/impl/dev_poll_reactor.hpp b/include/boost/asio/detail/impl/dev_poll_reactor.hpp
index 623346edd5..c01450ffea 100644
--- a/include/boost/asio/detail/impl/dev_poll_reactor.hpp
+++ b/include/boost/asio/detail/impl/dev_poll_reactor.hpp
@@ -46,12 +46,12 @@ void dev_poll_reactor::schedule_timer(timer_queue<Time_Traits>& queue,
 
   if (shutdown_)
   {
-    io_service_.post_immediate_completion(op, false);
+    scheduler_.post_immediate_completion(op, false);
     return;
   }
 
   bool earliest = queue.enqueue_timer(time, timer, op);
-  io_service_.work_started();
+  scheduler_.work_started();
   if (earliest)
     interrupter_.interrupt();
 }
@@ -65,10 +65,23 @@ std::size_t dev_poll_reactor::cancel_timer(timer_queue<Time_Traits>& queue,
   op_queue<operation> ops;
   std::size_t n = queue.cancel_timer(timer, ops, max_cancelled);
   lock.unlock();
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
   return n;
 }
 
+template <typename Time_Traits>
+void dev_poll_reactor::move_timer(timer_queue<Time_Traits>& queue,
+    typename timer_queue<Time_Traits>::per_timer_data& target,
+    typename timer_queue<Time_Traits>::per_timer_data& source)
+{
+  boost::asio::detail::mutex::scoped_lock lock(mutex_);
+  op_queue<operation> ops;
+  queue.cancel_timer(target, ops);
+  queue.move_timer(target, source);
+  lock.unlock();
+  scheduler_.post_deferred_completions(ops);
+}
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/detail/impl/dev_poll_reactor.ipp b/include/boost/asio/detail/impl/dev_poll_reactor.ipp
index 7efb05ed02..5186d30473 100644
--- a/include/boost/asio/detail/impl/dev_poll_reactor.ipp
+++ b/include/boost/asio/detail/impl/dev_poll_reactor.ipp
@@ -30,9 +30,9 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-dev_poll_reactor::dev_poll_reactor(boost::asio::io_service& io_service)
-  : boost::asio::detail::service_base<dev_poll_reactor>(io_service),
-    io_service_(use_service<io_service_impl>(io_service)),
+dev_poll_reactor::dev_poll_reactor(boost::asio::execution_context& ctx)
+  : boost::asio::detail::execution_context_service_base<dev_poll_reactor>(ctx),
+    scheduler_(use_service<scheduler>(ctx)),
     mutex_(),
     dev_poll_fd_(do_dev_poll_create()),
     interrupter_(),
@@ -48,11 +48,11 @@ dev_poll_reactor::dev_poll_reactor(boost::asio::io_service& io_service)
 
 dev_poll_reactor::~dev_poll_reactor()
 {
-  shutdown_service();
+  shutdown();
   ::close(dev_poll_fd_);
 }
 
-void dev_poll_reactor::shutdown_service()
+void dev_poll_reactor::shutdown()
 {
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
   shutdown_ = true;
@@ -65,12 +65,13 @@ void dev_poll_reactor::shutdown_service()
 
   timer_queues_.get_all_timers(ops);
 
-  io_service_.abandon_operations(ops);
+  scheduler_.abandon_operations(ops);
 } 
 
-void dev_poll_reactor::fork_service(boost::asio::io_service::fork_event fork_ev)
+void dev_poll_reactor::notify_fork(
+    boost::asio::execution_context::fork_event fork_ev)
 {
-  if (fork_ev == boost::asio::io_service::fork_child)
+  if (fork_ev == boost::asio::execution_context::fork_child)
   {
     detail::mutex::scoped_lock lock(mutex_);
 
@@ -113,7 +114,7 @@ void dev_poll_reactor::fork_service(boost::asio::io_service::fork_event fork_ev)
 
 void dev_poll_reactor::init_task()
 {
-  io_service_.init_task();
+  scheduler_.init_task();
 }
 
 int dev_poll_reactor::register_descriptor(socket_type, per_descriptor_data&)
@@ -168,7 +169,7 @@ void dev_poll_reactor::start_op(int op_type, socket_type descriptor,
         if (op->perform())
         {
           lock.unlock();
-          io_service_.post_immediate_completion(op, is_continuation);
+          scheduler_.post_immediate_completion(op, is_continuation);
           return;
         }
       }
@@ -176,7 +177,7 @@ void dev_poll_reactor::start_op(int op_type, socket_type descriptor,
   }
 
   bool first = op_queue_[op_type].enqueue_operation(descriptor, op);
-  io_service_.work_started();
+  scheduler_.work_started();
   if (first)
   {
     ::pollfd& ev = add_pending_event_change(descriptor);
@@ -240,13 +241,13 @@ void dev_poll_reactor::cleanup_descriptor_data(
 {
 }
 
-void dev_poll_reactor::run(bool block, op_queue<operation>& ops)
+void dev_poll_reactor::run(long usec, op_queue<operation>& ops)
 {
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
 
   // We can return immediately if there's no work to do and the reactor is
   // not supposed to block.
-  if (!block && op_queue_[read_op].empty() && op_queue_[write_op].empty()
+  if (usec == 0 && op_queue_[read_op].empty() && op_queue_[write_op].empty()
       && op_queue_[except_op].empty() && timer_queues_.all_empty())
     return;
 
@@ -272,7 +273,15 @@ void dev_poll_reactor::run(bool block, op_queue<operation>& ops)
     pending_event_change_index_.clear();
   }
 
-  int timeout = block ? get_timeout() : 0;
+  // Calculate timeout.
+  int timeout;
+  if (usec == 0)
+    timeout = 0;
+  else
+  {
+    timeout = (usec < 0) ? -1 : ((usec - 1) / 1000 + 1);
+    timeout = get_timeout(timeout);
+  }
   lock.unlock();
 
   // Block on the /dev/poll descriptor.
@@ -386,11 +395,13 @@ void dev_poll_reactor::do_remove_timer_queue(timer_queue_base& queue)
   timer_queues_.erase(&queue);
 }
 
-int dev_poll_reactor::get_timeout()
+int dev_poll_reactor::get_timeout(int msec)
 {
   // By default we will wait no longer than 5 minutes. This will ensure that
   // any changes to the system clock are detected after no longer than this.
-  return timer_queues_.wait_duration_msec(5 * 60 * 1000);
+  const int max_msec = 5 * 60 * 1000;
+  return timer_queues_.wait_duration_msec(
+      (msec < 0 || max_msec < msec) ? max_msec : msec);
 }
 
 void dev_poll_reactor::cancel_ops_unlocked(socket_type descriptor,
@@ -401,7 +412,7 @@ void dev_poll_reactor::cancel_ops_unlocked(socket_type descriptor,
   for (int i = 0; i < max_ops; ++i)
     need_interrupt = op_queue_[i].cancel_operations(
         descriptor, ops, ec) || need_interrupt;
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
   if (need_interrupt)
     interrupter_.interrupt();
 }
diff --git a/include/boost/asio/detail/impl/epoll_reactor.hpp b/include/boost/asio/detail/impl/epoll_reactor.hpp
index ea5c6bfc69..537b0fc7da 100644
--- a/include/boost/asio/detail/impl/epoll_reactor.hpp
+++ b/include/boost/asio/detail/impl/epoll_reactor.hpp
@@ -44,12 +44,12 @@ void epoll_reactor::schedule_timer(timer_queue<Time_Traits>& queue,
 
   if (shutdown_)
   {
-    io_service_.post_immediate_completion(op, false);
+    scheduler_.post_immediate_completion(op, false);
     return;
   }
 
   bool earliest = queue.enqueue_timer(time, timer, op);
-  io_service_.work_started();
+  scheduler_.work_started();
   if (earliest)
     update_timeout();
 }
@@ -63,10 +63,23 @@ std::size_t epoll_reactor::cancel_timer(timer_queue<Time_Traits>& queue,
   op_queue<operation> ops;
   std::size_t n = queue.cancel_timer(timer, ops, max_cancelled);
   lock.unlock();
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
   return n;
 }
 
+template <typename Time_Traits>
+void epoll_reactor::move_timer(timer_queue<Time_Traits>& queue,
+    typename timer_queue<Time_Traits>::per_timer_data& target,
+    typename timer_queue<Time_Traits>::per_timer_data& source)
+{
+  mutex::scoped_lock lock(mutex_);
+  op_queue<operation> ops;
+  queue.cancel_timer(target, ops);
+  queue.move_timer(target, source);
+  lock.unlock();
+  scheduler_.post_deferred_completions(ops);
+}
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/detail/impl/epoll_reactor.ipp b/include/boost/asio/detail/impl/epoll_reactor.ipp
index 3d3d244e0a..f66e8e5950 100644
--- a/include/boost/asio/detail/impl/epoll_reactor.ipp
+++ b/include/boost/asio/detail/impl/epoll_reactor.ipp
@@ -35,14 +35,16 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-epoll_reactor::epoll_reactor(boost::asio::io_service& io_service)
-  : boost::asio::detail::service_base<epoll_reactor>(io_service),
-    io_service_(use_service<io_service_impl>(io_service)),
-    mutex_(),
+epoll_reactor::epoll_reactor(boost::asio::execution_context& ctx)
+  : execution_context_service_base<epoll_reactor>(ctx),
+    scheduler_(use_service<scheduler>(ctx)),
+    mutex_(BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(
+          REACTOR_REGISTRATION, scheduler_.concurrency_hint())),
     interrupter_(),
     epoll_fd_(do_epoll_create()),
     timer_fd_(do_timerfd_create()),
-    shutdown_(false)
+    shutdown_(false),
+    registered_descriptors_mutex_(mutex_.enabled())
 {
   // Add the interrupter's descriptor to epoll.
   epoll_event ev = { 0, { 0 } };
@@ -68,7 +70,7 @@ epoll_reactor::~epoll_reactor()
     close(timer_fd_);
 }
 
-void epoll_reactor::shutdown_service()
+void epoll_reactor::shutdown()
 {
   mutex::scoped_lock lock(mutex_);
   shutdown_ = true;
@@ -86,12 +88,13 @@ void epoll_reactor::shutdown_service()
 
   timer_queues_.get_all_timers(ops);
 
-  io_service_.abandon_operations(ops);
+  scheduler_.abandon_operations(ops);
 }
 
-void epoll_reactor::fork_service(boost::asio::io_service::fork_event fork_ev)
+void epoll_reactor::notify_fork(
+    boost::asio::execution_context::fork_event fork_ev)
 {
-  if (fork_ev == boost::asio::io_service::fork_child)
+  if (fork_ev == boost::asio::execution_context::fork_child)
   {
     if (epoll_fd_ != -1)
       ::close(epoll_fd_);
@@ -142,7 +145,7 @@ void epoll_reactor::fork_service(boost::asio::io_service::fork_event fork_ev)
 
 void epoll_reactor::init_task()
 {
-  io_service_.init_task();
+  scheduler_.init_task();
 }
 
 int epoll_reactor::register_descriptor(socket_type descriptor,
@@ -150,12 +153,18 @@ int epoll_reactor::register_descriptor(socket_type descriptor,
 {
   descriptor_data = allocate_descriptor_state();
 
+  BOOST_ASIO_HANDLER_REACTOR_REGISTRATION((
+        context(), static_cast<uintmax_t>(descriptor),
+        reinterpret_cast<uintmax_t>(descriptor_data)));
+
   {
     mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
 
     descriptor_data->reactor_ = this;
     descriptor_data->descriptor_ = descriptor;
     descriptor_data->shutdown_ = false;
+    for (int i = 0; i < max_ops; ++i)
+      descriptor_data->try_speculative_[i] = true;
   }
 
   epoll_event ev = { 0, { 0 } };
@@ -186,6 +195,10 @@ int epoll_reactor::register_internal_descriptor(
 {
   descriptor_data = allocate_descriptor_state();
 
+  BOOST_ASIO_HANDLER_REACTOR_REGISTRATION((
+        context(), static_cast<uintmax_t>(descriptor),
+        reinterpret_cast<uintmax_t>(descriptor_data)));
+
   {
     mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);
 
@@ -193,6 +206,8 @@ int epoll_reactor::register_internal_descriptor(
     descriptor_data->descriptor_ = descriptor;
     descriptor_data->shutdown_ = false;
     descriptor_data->op_queue_[op_type].push(op);
+    for (int i = 0; i < max_ops; ++i)
+      descriptor_data->try_speculative_[i] = true;
   }
 
   epoll_event ev = { 0, { 0 } };
@@ -239,17 +254,23 @@ void epoll_reactor::start_op(int op_type, socket_type descriptor,
         && (op_type != read_op
           || descriptor_data->op_queue_[except_op].empty()))
     {
-      if (op->perform())
+      if (descriptor_data->try_speculative_[op_type])
       {
-        descriptor_lock.unlock();
-        io_service_.post_immediate_completion(op, is_continuation);
-        return;
+        if (reactor_op::status status = op->perform())
+        {
+          if (status == reactor_op::done_and_exhausted)
+            if (descriptor_data->registered_events_ != 0)
+              descriptor_data->try_speculative_[op_type] = false;
+          descriptor_lock.unlock();
+          scheduler_.post_immediate_completion(op, is_continuation);
+          return;
+        }
       }
 
       if (descriptor_data->registered_events_ == 0)
       {
         op->ec_ = boost::asio::error::operation_not_supported;
-        io_service_.post_immediate_completion(op, is_continuation);
+        scheduler_.post_immediate_completion(op, is_continuation);
         return;
       }
 
@@ -268,7 +289,7 @@ void epoll_reactor::start_op(int op_type, socket_type descriptor,
           {
             op->ec_ = boost::system::error_code(errno,
                 boost::asio::error::get_system_category());
-            io_service_.post_immediate_completion(op, is_continuation);
+            scheduler_.post_immediate_completion(op, is_continuation);
             return;
           }
         }
@@ -277,7 +298,7 @@ void epoll_reactor::start_op(int op_type, socket_type descriptor,
     else if (descriptor_data->registered_events_ == 0)
     {
       op->ec_ = boost::asio::error::operation_not_supported;
-      io_service_.post_immediate_completion(op, is_continuation);
+      scheduler_.post_immediate_completion(op, is_continuation);
       return;
     }
     else
@@ -295,7 +316,7 @@ void epoll_reactor::start_op(int op_type, socket_type descriptor,
   }
 
   descriptor_data->op_queue_[op_type].push(op);
-  io_service_.work_started();
+  scheduler_.work_started();
 }
 
 void epoll_reactor::cancel_ops(socket_type,
@@ -319,7 +340,7 @@ void epoll_reactor::cancel_ops(socket_type,
 
   descriptor_lock.unlock();
 
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
 }
 
 void epoll_reactor::deregister_descriptor(socket_type descriptor,
@@ -359,16 +380,11 @@ void epoll_reactor::deregister_descriptor(socket_type descriptor,
 
     descriptor_lock.unlock();
 
-    io_service_.post_deferred_completions(ops);
+    BOOST_ASIO_HANDLER_REACTOR_DEREGISTRATION((
+          context(), static_cast<uintmax_t>(descriptor),
+          reinterpret_cast<uintmax_t>(descriptor_data)));
 
-    // Leave descriptor_data set so that it will be freed by the subsequent
-    // call to cleanup_descriptor_data.
-  }
-  else
-  {
-    // We are shutting down, so prevent cleanup_descriptor_data from freeing
-    // the descriptor_data object and let the destructor free it instead.
-    descriptor_data = 0;
+    scheduler_.post_deferred_completions(ops);
   }
 }
 
@@ -394,14 +410,9 @@ void epoll_reactor::deregister_internal_descriptor(socket_type descriptor,
 
     descriptor_lock.unlock();
 
-    // Leave descriptor_data set so that it will be freed by the subsequent
-    // call to cleanup_descriptor_data.
-  }
-  else
-  {
-    // We are shutting down, so prevent cleanup_descriptor_data from freeing
-    // the descriptor_data object and let the destructor free it instead.
-    descriptor_data = 0;
+    BOOST_ASIO_HANDLER_REACTOR_DEREGISTRATION((
+          context(), static_cast<uintmax_t>(descriptor),
+          reinterpret_cast<uintmax_t>(descriptor_data)));
   }
 }
 
@@ -415,28 +426,62 @@ void epoll_reactor::cleanup_descriptor_data(
   }
 }
 
-void epoll_reactor::run(bool block, op_queue<operation>& ops)
+void epoll_reactor::run(long usec, op_queue<operation>& ops)
 {
-  // This code relies on the fact that the task_io_service queues the reactor
-  // task behind all descriptor operations generated by this function. This
-  // means, that by the time we reach this point, any previously returned
-  // descriptor operations have already been dequeued. Therefore it is now safe
-  // for us to reuse and return them for the task_io_service to queue again.
+  // This code relies on the fact that the scheduler queues the reactor task
+  // behind all descriptor operations generated by this function. This means,
+  // that by the time we reach this point, any previously returned descriptor
+  // operations have already been dequeued. Therefore it is now safe for us to
+  // reuse and return them for the scheduler to queue again.
 
-  // Calculate a timeout only if timerfd is not used.
+  // Calculate timeout. Check the timer queues only if timerfd is not in use.
   int timeout;
-  if (timer_fd_ != -1)
-    timeout = block ? -1 : 0;
+  if (usec == 0)
+    timeout = 0;
   else
   {
-    mutex::scoped_lock lock(mutex_);
-    timeout = block ? get_timeout() : 0;
+    timeout = (usec < 0) ? -1 : ((usec - 1) / 1000 + 1);
+    if (timer_fd_ == -1)
+    {
+      mutex::scoped_lock lock(mutex_);
+      timeout = get_timeout(timeout);
+    }
   }
 
   // Block on the epoll descriptor.
   epoll_event events[128];
   int num_events = epoll_wait(epoll_fd_, events, 128, timeout);
 
+#if defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+  // Trace the waiting events.
+  for (int i = 0; i < num_events; ++i)
+  {
+    void* ptr = events[i].data.ptr;
+    if (ptr == &interrupter_)
+    {
+      // Ignore.
+    }
+# if defined(BOOST_ASIO_HAS_TIMERFD)
+    else if (ptr == &timer_fd_)
+    {
+      // Ignore.
+    }
+# endif // defined(BOOST_ASIO_HAS_TIMERFD)
+    else
+    {
+      unsigned event_mask = 0;
+      if ((events[i].events & EPOLLIN) != 0)
+        event_mask |= BOOST_ASIO_HANDLER_REACTOR_READ_EVENT;
+      if ((events[i].events & EPOLLOUT))
+        event_mask |= BOOST_ASIO_HANDLER_REACTOR_WRITE_EVENT;
+      if ((events[i].events & (EPOLLERR | EPOLLHUP)) != 0)
+        event_mask |= BOOST_ASIO_HANDLER_REACTOR_ERROR_EVENT;
+      BOOST_ASIO_HANDLER_REACTOR_EVENTS((context(),
+            reinterpret_cast<uintmax_t>(ptr), event_mask));
+    }
+  }
+#endif // defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+
 #if defined(BOOST_ASIO_HAS_TIMERFD)
   bool check_timers = (timer_fd_ == -1);
 #else // defined(BOOST_ASIO_HAS_TIMERFD)
@@ -470,7 +515,7 @@ void epoll_reactor::run(bool block, op_queue<operation>& ops)
     else
     {
       // The descriptor operation doesn't count as work in and of itself, so we
-      // don't call work_started() here. This still allows the io_service to
+      // don't call work_started() here. This still allows the scheduler to
       // stop if the only remaining operations are descriptor operations.
       descriptor_state* descriptor_data = static_cast<descriptor_state*>(ptr);
       if (!ops.is_enqueued(descriptor_data))
@@ -562,7 +607,8 @@ int epoll_reactor::do_timerfd_create()
 epoll_reactor::descriptor_state* epoll_reactor::allocate_descriptor_state()
 {
   mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_);
-  return registered_descriptors_.alloc();
+  return registered_descriptors_.alloc(BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(
+        REACTOR_IO, scheduler_.concurrency_hint()));
 }
 
 void epoll_reactor::free_descriptor_state(epoll_reactor::descriptor_state* s)
@@ -598,11 +644,13 @@ void epoll_reactor::update_timeout()
   interrupt();
 }
 
-int epoll_reactor::get_timeout()
+int epoll_reactor::get_timeout(int msec)
 {
   // By default we will wait no longer than 5 minutes. This will ensure that
   // any changes to the system clock are detected after no longer than this.
-  return timer_queues_.wait_duration_msec(5 * 60 * 1000);
+  const int max_msec = 5 * 60 * 1000;
+  return timer_queues_.wait_duration_msec(
+      (msec < 0 || max_msec < msec) ? max_msec : msec);
 }
 
 #if defined(BOOST_ASIO_HAS_TIMERFD)
@@ -632,19 +680,18 @@ struct epoll_reactor::perform_io_cleanup_on_block_exit
     {
       // Post the remaining completed operations for invocation.
       if (!ops_.empty())
-        reactor_->io_service_.post_deferred_completions(ops_);
+        reactor_->scheduler_.post_deferred_completions(ops_);
 
       // A user-initiated operation has completed, but there's no need to
       // explicitly call work_finished() here. Instead, we'll take advantage of
-      // the fact that the task_io_service will call work_finished() once we
-      // return.
+      // the fact that the scheduler will call work_finished() once we return.
     }
     else
     {
       // No user-initiated operations have completed, so we need to compensate
-      // for the work_finished() call that the task_io_service will make once
-      // this operation returns.
-      reactor_->io_service_.work_started();
+      // for the work_finished() call that the scheduler will make once this
+      // operation returns.
+      reactor_->scheduler_.compensating_work_started();
     }
   }
 
@@ -653,8 +700,9 @@ struct epoll_reactor::perform_io_cleanup_on_block_exit
   operation* first_op_;
 };
 
-epoll_reactor::descriptor_state::descriptor_state()
-  : operation(&epoll_reactor::descriptor_state::do_complete)
+epoll_reactor::descriptor_state::descriptor_state(bool locking)
+  : operation(&epoll_reactor::descriptor_state::do_complete),
+    mutex_(locking)
 {
 }
 
@@ -671,12 +719,18 @@ operation* epoll_reactor::descriptor_state::perform_io(uint32_t events)
   {
     if (events & (flag[j] | EPOLLERR | EPOLLHUP))
     {
+      try_speculative_[j] = true;
       while (reactor_op* op = op_queue_[j].front())
       {
-        if (op->perform())
+        if (reactor_op::status status = op->perform())
         {
           op_queue_[j].pop();
           io_cleanup.ops_.push(op);
+          if (status == reactor_op::done_and_exhausted)
+          {
+            try_speculative_[j] = false;
+            break;
+          }
         }
         else
           break;
@@ -692,7 +746,7 @@ operation* epoll_reactor::descriptor_state::perform_io(uint32_t events)
 }
 
 void epoll_reactor::descriptor_state::do_complete(
-    io_service_impl* owner, operation* base,
+    void* owner, operation* base,
     const boost::system::error_code& ec, std::size_t bytes_transferred)
 {
   if (owner)
@@ -701,7 +755,7 @@ void epoll_reactor::descriptor_state::do_complete(
     uint32_t events = static_cast<uint32_t>(bytes_transferred);
     if (operation* op = descriptor_data->perform_io(events))
     {
-      op->complete(*owner, ec, 0);
+      op->complete(owner, ec, 0);
     }
   }
 }
diff --git a/include/boost/asio/detail/impl/handler_tracking.ipp b/include/boost/asio/detail/impl/handler_tracking.ipp
index 259b5ab62b..aa6b9b2917 100644
--- a/include/boost/asio/detail/impl/handler_tracking.ipp
+++ b/include/boost/asio/detail/impl/handler_tracking.ipp
@@ -17,7 +17,11 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+#if defined(BOOST_ASIO_CUSTOM_HANDLER_TRACKING)
+
+// The handler tracking implementation is provided by the user-specified header.
+
+#elif defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
 
 #include <cstdarg>
 #include <cstdio>
@@ -25,17 +29,15 @@
 
 #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 # include <boost/asio/time_traits.hpp>
-#else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-# if defined(BOOST_ASIO_HAS_STD_CHRONO)
-#  include <chrono>
-# elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-#  include <boost/chrono/system_clocks.hpp>
-# endif
+#elif defined(BOOST_ASIO_HAS_CHRONO)
+# include <boost/asio/detail/chrono.hpp>
 # include <boost/asio/detail/chrono_time_traits.hpp>
 # include <boost/asio/wait_traits.hpp>
 #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 
-#if !defined(BOOST_ASIO_WINDOWS)
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+# include <boost/asio/detail/socket_types.hpp>
+#elif !defined(BOOST_ASIO_WINDOWS)
 # include <unistd.h>
 #endif // !defined(BOOST_ASIO_WINDOWS)
 
@@ -56,16 +58,11 @@ struct handler_tracking_timestamp
     boost::posix_time::ptime epoch(boost::gregorian::date(1970, 1, 1));
     boost::posix_time::time_duration now =
       boost::posix_time::microsec_clock::universal_time() - epoch;
-#elif defined(BOOST_ASIO_HAS_STD_CHRONO)
-    typedef chrono_time_traits<std::chrono::system_clock,
-        boost::asio::wait_traits<std::chrono::system_clock> > traits_helper;
-    traits_helper::posix_time_duration now(
-        std::chrono::system_clock::now().time_since_epoch());
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-    typedef chrono_time_traits<boost::chrono::system_clock,
-        boost::asio::wait_traits<boost::chrono::system_clock> > traits_helper;
+#elif defined(BOOST_ASIO_HAS_CHRONO)
+    typedef chrono_time_traits<chrono::system_clock,
+        boost::asio::wait_traits<chrono::system_clock> > traits_helper;
     traits_helper::posix_time_duration now(
-        boost::chrono::system_clock::now().time_since_epoch());
+        chrono::system_clock::now().time_since_epoch());
 #endif
     seconds = static_cast<uint64_t>(now.total_seconds());
     microseconds = static_cast<uint64_t>(now.total_microseconds() % 1000000);
@@ -96,13 +93,15 @@ void handler_tracking::init()
     state->current_completion_ = new tss_ptr<completion>;
 }
 
-void handler_tracking::creation(handler_tracking::tracked_handler* h,
-    const char* object_type, void* object, const char* op_name)
+void handler_tracking::creation(execution_context&,
+    handler_tracking::tracked_handler& h,
+    const char* object_type, void* object,
+    uintmax_t /*native_handle*/, const char* op_name)
 {
   static tracking_state* state = get_state();
 
   static_mutex::scoped_lock lock(state->mutex_);
-  h->id_ = state->next_id_++;
+  h.id_ = state->next_id_++;
   lock.unlock();
 
   handler_tracking_timestamp timestamp;
@@ -118,11 +117,12 @@ void handler_tracking::creation(handler_tracking::tracked_handler* h,
       "@asio|%llu.%06llu|%llu*%llu|%.20s@%p.%.50s\n",
 #endif // defined(BOOST_ASIO_WINDOWS)
       timestamp.seconds, timestamp.microseconds,
-      current_id, h->id_, object_type, object, op_name);
+      current_id, h.id_, object_type, object, op_name);
 }
 
-handler_tracking::completion::completion(handler_tracking::tracked_handler* h)
-  : id_(h->id_),
+handler_tracking::completion::completion(
+    const handler_tracking::tracked_handler& h)
+  : id_(h.id_),
     invoked_(false),
     next_(*get_state()->current_completion_)
 {
@@ -250,8 +250,9 @@ void handler_tracking::completion::invocation_end()
   }
 }
 
-void handler_tracking::operation(const char* object_type,
-    void* object, const char* op_name)
+void handler_tracking::operation(execution_context&,
+    const char* object_type, void* object,
+    uintmax_t /*native_handle*/, const char* op_name)
 {
   static tracking_state* state = get_state();
 
@@ -271,6 +272,54 @@ void handler_tracking::operation(const char* object_type,
       current_id, object_type, object, op_name);
 }
 
+void handler_tracking::reactor_registration(execution_context& /*context*/,
+    uintmax_t /*native_handle*/, uintmax_t /*registration*/)
+{
+}
+
+void handler_tracking::reactor_deregistration(execution_context& /*context*/,
+    uintmax_t /*native_handle*/, uintmax_t /*registration*/)
+{
+}
+
+void handler_tracking::reactor_events(execution_context& /*context*/,
+    uintmax_t /*native_handle*/, unsigned /*events*/)
+{
+}
+
+void handler_tracking::reactor_operation(
+    const tracked_handler& h, const char* op_name,
+    const boost::system::error_code& ec)
+{
+  handler_tracking_timestamp timestamp;
+
+  write_line(
+#if defined(BOOST_ASIO_WINDOWS)
+      "@asio|%I64u.%06I64u|.%I64u|%s,ec=%.20s:%d\n",
+#else // defined(BOOST_ASIO_WINDOWS)
+      "@asio|%llu.%06llu|.%llu|%s,ec=%.20s:%d\n",
+#endif // defined(BOOST_ASIO_WINDOWS)
+      timestamp.seconds, timestamp.microseconds,
+      h.id_, op_name, ec.category().name(), ec.value());
+}
+
+void handler_tracking::reactor_operation(
+    const tracked_handler& h, const char* op_name,
+    const boost::system::error_code& ec, std::size_t bytes_transferred)
+{
+  handler_tracking_timestamp timestamp;
+
+  write_line(
+#if defined(BOOST_ASIO_WINDOWS)
+      "@asio|%I64u.%06I64u|.%I64u|%s,ec=%.20s:%d,bytes_transferred=%I64u\n",
+#else // defined(BOOST_ASIO_WINDOWS)
+      "@asio|%llu.%06llu|.%llu|%s,ec=%.20s:%d,bytes_transferred=%llu\n",
+#endif // defined(BOOST_ASIO_WINDOWS)
+      timestamp.seconds, timestamp.microseconds,
+      h.id_, op_name, ec.category().name(), ec.value(),
+      static_cast<uint64_t>(bytes_transferred));
+}
+
 void handler_tracking::write_line(const char* format, ...)
 {
   using namespace std; // For sprintf (or equivalent).
@@ -287,7 +336,11 @@ void handler_tracking::write_line(const char* format, ...)
 
   va_end(args);
 
-#if defined(BOOST_ASIO_WINDOWS)
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+  wchar_t wline[256] = L"";
+  mbstowcs_s(0, wline, sizeof(wline) / sizeof(wchar_t), line, length);
+  ::OutputDebugStringW(wline);
+#elif defined(BOOST_ASIO_WINDOWS)
   HANDLE stderr_handle = ::GetStdHandle(STD_ERROR_HANDLE);
   DWORD bytes_written = 0;
   ::WriteFile(stderr_handle, line, length, &bytes_written, 0);
diff --git a/include/boost/asio/detail/impl/kqueue_reactor.hpp b/include/boost/asio/detail/impl/kqueue_reactor.hpp
index 93cbca26a2..83bfa95765 100644
--- a/include/boost/asio/detail/impl/kqueue_reactor.hpp
+++ b/include/boost/asio/detail/impl/kqueue_reactor.hpp
@@ -44,16 +44,16 @@ void kqueue_reactor::schedule_timer(timer_queue<Time_Traits>& queue,
     const typename Time_Traits::time_type& time,
     typename timer_queue<Time_Traits>::per_timer_data& timer, wait_op* op)
 {
-  boost::asio::detail::mutex::scoped_lock lock(mutex_);
+  mutex::scoped_lock lock(mutex_);
 
   if (shutdown_)
   {
-    io_service_.post_immediate_completion(op, false);
+    scheduler_.post_immediate_completion(op, false);
     return;
   }
 
   bool earliest = queue.enqueue_timer(time, timer, op);
-  io_service_.work_started();
+  scheduler_.work_started();
   if (earliest)
     interrupt();
 }
@@ -63,14 +63,27 @@ std::size_t kqueue_reactor::cancel_timer(timer_queue<Time_Traits>& queue,
     typename timer_queue<Time_Traits>::per_timer_data& timer,
     std::size_t max_cancelled)
 {
-  boost::asio::detail::mutex::scoped_lock lock(mutex_);
+  mutex::scoped_lock lock(mutex_);
   op_queue<operation> ops;
   std::size_t n = queue.cancel_timer(timer, ops, max_cancelled);
   lock.unlock();
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
   return n;
 }
 
+template <typename Time_Traits>
+void kqueue_reactor::move_timer(timer_queue<Time_Traits>& queue,
+    typename timer_queue<Time_Traits>::per_timer_data& target,
+    typename timer_queue<Time_Traits>::per_timer_data& source)
+{
+  mutex::scoped_lock lock(mutex_);
+  op_queue<operation> ops;
+  queue.cancel_timer(target, ops);
+  queue.move_timer(target, source);
+  lock.unlock();
+  scheduler_.post_deferred_completions(ops);
+}
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/detail/impl/kqueue_reactor.ipp b/include/boost/asio/detail/impl/kqueue_reactor.ipp
index 8057606ce6..8656880eb8 100644
--- a/include/boost/asio/detail/impl/kqueue_reactor.ipp
+++ b/include/boost/asio/detail/impl/kqueue_reactor.ipp
@@ -21,6 +21,7 @@
 #if defined(BOOST_ASIO_HAS_KQUEUE)
 
 #include <boost/asio/detail/kqueue_reactor.hpp>
+#include <boost/asio/detail/scheduler.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
 
@@ -39,13 +40,15 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-kqueue_reactor::kqueue_reactor(boost::asio::io_service& io_service)
-  : boost::asio::detail::service_base<kqueue_reactor>(io_service),
-    io_service_(use_service<io_service_impl>(io_service)),
-    mutex_(),
+kqueue_reactor::kqueue_reactor(boost::asio::execution_context& ctx)
+  : execution_context_service_base<kqueue_reactor>(ctx),
+    scheduler_(use_service<scheduler>(ctx)),
+    mutex_(BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(
+          REACTOR_REGISTRATION, scheduler_.concurrency_hint())),
     kqueue_fd_(do_kqueue_create()),
     interrupter_(),
-    shutdown_(false)
+    shutdown_(false),
+    registered_descriptors_mutex_(mutex_.enabled())
 {
   struct kevent events[1];
   BOOST_ASIO_KQUEUE_EV_SET(&events[0], interrupter_.read_descriptor(),
@@ -63,7 +66,7 @@ kqueue_reactor::~kqueue_reactor()
   close(kqueue_fd_);
 }
 
-void kqueue_reactor::shutdown_service()
+void kqueue_reactor::shutdown()
 {
   mutex::scoped_lock lock(mutex_);
   shutdown_ = true;
@@ -81,12 +84,13 @@ void kqueue_reactor::shutdown_service()
 
   timer_queues_.get_all_timers(ops);
 
-  io_service_.abandon_operations(ops);
+  scheduler_.abandon_operations(ops);
 }
 
-void kqueue_reactor::fork_service(boost::asio::io_service::fork_event fork_ev)
+void kqueue_reactor::notify_fork(
+    boost::asio::execution_context::fork_event fork_ev)
 {
-  if (fork_ev == boost::asio::io_service::fork_child)
+  if (fork_ev == boost::asio::execution_context::fork_child)
   {
     // The kqueue descriptor is automatically closed in the child.
     kqueue_fd_ = -1;
@@ -128,7 +132,7 @@ void kqueue_reactor::fork_service(boost::asio::io_service::fork_event fork_ev)
 
 void kqueue_reactor::init_task()
 {
-  io_service_.init_task();
+  scheduler_.init_task();
 }
 
 int kqueue_reactor::register_descriptor(socket_type descriptor,
@@ -136,6 +140,10 @@ int kqueue_reactor::register_descriptor(socket_type descriptor,
 {
   descriptor_data = allocate_descriptor_state();
 
+  BOOST_ASIO_HANDLER_REACTOR_REGISTRATION((
+        context(), static_cast<uintmax_t>(descriptor),
+        reinterpret_cast<uintmax_t>(descriptor_data)));
+
   mutex::scoped_lock lock(descriptor_data->mutex_);
 
   descriptor_data->descriptor_ = descriptor;
@@ -151,6 +159,10 @@ int kqueue_reactor::register_internal_descriptor(
 {
   descriptor_data = allocate_descriptor_state();
 
+  BOOST_ASIO_HANDLER_REACTOR_REGISTRATION((
+        context(), static_cast<uintmax_t>(descriptor),
+        reinterpret_cast<uintmax_t>(descriptor_data)));
+
   mutex::scoped_lock lock(descriptor_data->mutex_);
 
   descriptor_data->descriptor_ = descriptor;
@@ -205,7 +217,7 @@ void kqueue_reactor::start_op(int op_type, socket_type descriptor,
       if (op->perform())
       {
         descriptor_lock.unlock();
-        io_service_.post_immediate_completion(op, is_continuation);
+        scheduler_.post_immediate_completion(op, is_continuation);
         return;
       }
 
@@ -224,7 +236,7 @@ void kqueue_reactor::start_op(int op_type, socket_type descriptor,
         {
           op->ec_ = boost::system::error_code(errno,
               boost::asio::error::get_system_category());
-          io_service_.post_immediate_completion(op, is_continuation);
+          scheduler_.post_immediate_completion(op, is_continuation);
           return;
         }
       }
@@ -244,7 +256,7 @@ void kqueue_reactor::start_op(int op_type, socket_type descriptor,
   }
 
   descriptor_data->op_queue_[op_type].push(op);
-  io_service_.work_started();
+  scheduler_.work_started();
 }
 
 void kqueue_reactor::cancel_ops(socket_type,
@@ -268,7 +280,7 @@ void kqueue_reactor::cancel_ops(socket_type,
 
   descriptor_lock.unlock();
 
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
 }
 
 void kqueue_reactor::deregister_descriptor(socket_type descriptor,
@@ -312,16 +324,11 @@ void kqueue_reactor::deregister_descriptor(socket_type descriptor,
 
     descriptor_lock.unlock();
 
-    io_service_.post_deferred_completions(ops);
+    BOOST_ASIO_HANDLER_REACTOR_DEREGISTRATION((
+          context(), static_cast<uintmax_t>(descriptor),
+          reinterpret_cast<uintmax_t>(descriptor_data)));
 
-    // Leave descriptor_data set so that it will be freed by the subsequent
-    // call to cleanup_descriptor_data.
-  }
-  else
-  {
-    // We are shutting down, so prevent cleanup_descriptor_data from freeing
-    // the descriptor_data object and let the destructor free it instead.
-    descriptor_data = 0;
+    scheduler_.post_deferred_completions(ops);
   }
 }
 
@@ -351,14 +358,9 @@ void kqueue_reactor::deregister_internal_descriptor(socket_type descriptor,
 
     descriptor_lock.unlock();
 
-    // Leave descriptor_data set so that it will be freed by the subsequent
-    // call to cleanup_descriptor_data.
-  }
-  else
-  {
-    // We are shutting down, so prevent cleanup_descriptor_data from freeing
-    // the descriptor_data object and let the destructor free it instead.
-    descriptor_data = 0;
+    BOOST_ASIO_HANDLER_REACTOR_DEREGISTRATION((
+          context(), static_cast<uintmax_t>(descriptor),
+          reinterpret_cast<uintmax_t>(descriptor_data)));
   }
 }
 
@@ -372,13 +374,13 @@ void kqueue_reactor::cleanup_descriptor_data(
   }
 }
 
-void kqueue_reactor::run(bool block, op_queue<operation>& ops)
+void kqueue_reactor::run(long usec, op_queue<operation>& ops)
 {
   mutex::scoped_lock lock(mutex_);
 
   // Determine how long to block while waiting for events.
   timespec timeout_buf = { 0, 0 };
-  timespec* timeout = block ? get_timeout(timeout_buf) : &timeout_buf;
+  timespec* timeout = usec ? get_timeout(usec, timeout_buf) : &timeout_buf;
 
   lock.unlock();
 
@@ -386,6 +388,31 @@ void kqueue_reactor::run(bool block, op_queue<operation>& ops)
   struct kevent events[128];
   int num_events = kevent(kqueue_fd_, 0, 0, events, 128, timeout);
 
+#if defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+  // Trace the waiting events.
+  for (int i = 0; i < num_events; ++i)
+  {
+    void* ptr = reinterpret_cast<void*>(events[i].udata);
+    if (ptr != &interrupter_)
+    {
+      unsigned event_mask = 0;
+      switch (events[i].filter)
+      {
+      case EVFILT_READ:
+        event_mask |= BOOST_ASIO_HANDLER_REACTOR_READ_EVENT;
+        break;
+      case EVFILT_WRITE:
+        event_mask |= BOOST_ASIO_HANDLER_REACTOR_WRITE_EVENT;
+        break;
+      }
+      if ((events[i].flags & (EV_ERROR | EV_OOBAND)) != 0)
+        event_mask |= BOOST_ASIO_HANDLER_REACTOR_ERROR_EVENT;
+      BOOST_ASIO_HANDLER_REACTOR_EVENTS((context(),
+            reinterpret_cast<uintmax_t>(ptr), event_mask));
+    }
+  }
+#endif // defined(BOOST_ASIO_ENABLE_HANDLER_TRACKING)
+
   // Dispatch the waiting events.
   for (int i = 0; i < num_events; ++i)
   {
@@ -476,7 +503,8 @@ int kqueue_reactor::do_kqueue_create()
 kqueue_reactor::descriptor_state* kqueue_reactor::allocate_descriptor_state()
 {
   mutex::scoped_lock descriptors_lock(registered_descriptors_mutex_);
-  return registered_descriptors_.alloc();
+  return registered_descriptors_.alloc(BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(
+        REACTOR_IO, scheduler_.concurrency_hint()));
 }
 
 void kqueue_reactor::free_descriptor_state(kqueue_reactor::descriptor_state* s)
@@ -497,11 +525,13 @@ void kqueue_reactor::do_remove_timer_queue(timer_queue_base& queue)
   timer_queues_.erase(&queue);
 }
 
-timespec* kqueue_reactor::get_timeout(timespec& ts)
+timespec* kqueue_reactor::get_timeout(long usec, timespec& ts)
 {
   // By default we will wait no longer than 5 minutes. This will ensure that
   // any changes to the system clock are detected after no longer than this.
-  long usec = timer_queues_.wait_duration_usec(5 * 60 * 1000 * 1000);
+  const long max_usec = 5 * 60 * 1000 * 1000;
+  usec = timer_queues_.wait_duration_usec(
+      (usec < 0 || max_usec < usec) ? max_usec : usec);
   ts.tv_sec = usec / 1000000;
   ts.tv_nsec = (usec % 1000000) * 1000;
   return &ts;
diff --git a/include/boost/asio/detail/impl/null_event.ipp b/include/boost/asio/detail/impl/null_event.ipp
new file mode 100644
index 0000000000..fb9f2e2ed2
--- /dev/null
+++ b/include/boost/asio/detail/impl/null_event.ipp
@@ -0,0 +1,76 @@
+//
+// detail/impl/null_event.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_IMPL_NULL_EVENT_IPP
+#define BOOST_ASIO_DETAIL_IMPL_NULL_EVENT_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+# include <thread>
+#elif defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
+# include <boost/asio/detail/socket_types.hpp>
+#else
+# include <unistd.h>
+# if defined(__hpux)
+#  include <sys/time.h>
+# endif
+# if !defined(__hpux) || defined(__SELECT)
+#  include <sys/select.h>
+# endif
+#endif
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+void null_event::do_wait()
+{
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+  std::this_thread::sleep_until((std::chrono::steady_clock::time_point::max)());
+#elif defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
+  ::Sleep(INFINITE);
+#else
+  ::pause();
+#endif
+}
+
+void null_event::do_wait_for_usec(long usec)
+{
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+  std::this_thread::sleep_for(std::chrono::microseconds(usec));
+#elif defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
+  ::Sleep(usec / 1000);
+#elif defined(__hpux) && defined(__SELECT)
+  timespec ts;
+  ts.tv_sec = usec / 1000000;
+  ts.tv_nsec = (usec % 1000000) * 1000;
+  ::pselect(0, 0, 0, 0, &ts, 0);
+#else
+  timeval tv;
+  tv.tv_sec = usec / 1000000;
+  tv.tv_usec = usec % 1000000;
+  ::select(0, 0, 0, 0, &tv);
+#endif
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_IMPL_NULL_EVENT_IPP
diff --git a/include/boost/asio/detail/impl/posix_event.ipp b/include/boost/asio/detail/impl/posix_event.ipp
index 3b465ca3cd..4ff246f301 100644
--- a/include/boost/asio/detail/impl/posix_event.ipp
+++ b/include/boost/asio/detail/impl/posix_event.ipp
@@ -32,7 +32,19 @@ namespace detail {
 posix_event::posix_event()
   : state_(0)
 {
+#if (defined(__MACH__) && defined(__APPLE__)) \
+      || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
   int error = ::pthread_cond_init(&cond_, 0);
+#else // (defined(__MACH__) && defined(__APPLE__))
+      // || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
+  ::pthread_condattr_t attr;
+  ::pthread_condattr_init(&attr);
+  int error = ::pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
+  if (error == 0)
+    error = ::pthread_cond_init(&cond_, &attr);
+#endif // (defined(__MACH__) && defined(__APPLE__))
+       // || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
+
   boost::system::error_code ec(error,
       boost::asio::error::get_system_category());
   boost::asio::detail::throw_error(ec, "event");
diff --git a/include/boost/asio/detail/impl/posix_thread.ipp b/include/boost/asio/detail/impl/posix_thread.ipp
index 66cb18da33..66a6792a4a 100644
--- a/include/boost/asio/detail/impl/posix_thread.ipp
+++ b/include/boost/asio/detail/impl/posix_thread.ipp
@@ -44,6 +44,16 @@ void posix_thread::join()
   }
 }
 
+std::size_t posix_thread::hardware_concurrency()
+{
+#if defined(_SC_NPROCESSORS_ONLN)
+  long result = sysconf(_SC_NPROCESSORS_ONLN);
+  if (result > 0)
+    return result;
+#endif // defined(_SC_NPROCESSORS_ONLN)
+  return 0;
+}
+
 void posix_thread::start_thread(func_base* arg)
 {
   int error = ::pthread_create(&thread_, 0,
diff --git a/include/boost/asio/detail/impl/reactive_descriptor_service.ipp b/include/boost/asio/detail/impl/reactive_descriptor_service.ipp
index a0300c47d0..ffb623839f 100644
--- a/include/boost/asio/detail/impl/reactive_descriptor_service.ipp
+++ b/include/boost/asio/detail/impl/reactive_descriptor_service.ipp
@@ -31,13 +31,14 @@ namespace asio {
 namespace detail {
 
 reactive_descriptor_service::reactive_descriptor_service(
-    boost::asio::io_service& io_service)
-  : reactor_(boost::asio::use_service<reactor>(io_service))
+    boost::asio::io_context& io_context)
+  : service_base<reactive_descriptor_service>(io_context),
+    reactor_(boost::asio::use_service<reactor>(io_context))
 {
   reactor_.init_task();
 }
 
-void reactive_descriptor_service::shutdown_service()
+void reactive_descriptor_service::shutdown()
 {
 }
 
@@ -84,7 +85,8 @@ void reactive_descriptor_service::destroy(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("descriptor", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+          "descriptor", &impl, impl.descriptor_, "close"));
 
     reactor_.deregister_descriptor(impl.descriptor_, impl.reactor_data_,
         (impl.state_ & descriptor_ops::possible_dup) == 0);
@@ -126,7 +128,8 @@ boost::system::error_code reactive_descriptor_service::close(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("descriptor", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+          "descriptor", &impl, impl.descriptor_, "close"));
 
     reactor_.deregister_descriptor(impl.descriptor_, impl.reactor_data_,
         (impl.state_ & descriptor_ops::possible_dup) == 0);
@@ -159,7 +162,8 @@ reactive_descriptor_service::release(
 
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("descriptor", &impl, "release"));
+    BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+          "descriptor", &impl, impl.descriptor_, "release"));
 
     reactor_.deregister_descriptor(impl.descriptor_, impl.reactor_data_, false);
     reactor_.cleanup_descriptor_data(impl.reactor_data_);
@@ -179,7 +183,8 @@ boost::system::error_code reactive_descriptor_service::cancel(
     return ec;
   }
 
-  BOOST_ASIO_HANDLER_OPERATION(("descriptor", &impl, "cancel"));
+  BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+        "descriptor", &impl, impl.descriptor_, "cancel"));
 
   reactor_.cancel_ops(impl.descriptor_, impl.reactor_data_);
   ec = boost::system::error_code();
diff --git a/include/boost/asio/detail/impl/reactive_serial_port_service.ipp b/include/boost/asio/detail/impl/reactive_serial_port_service.ipp
index ffa8857ab6..ec24abfda3 100644
--- a/include/boost/asio/detail/impl/reactive_serial_port_service.ipp
+++ b/include/boost/asio/detail/impl/reactive_serial_port_service.ipp
@@ -31,14 +31,15 @@ namespace asio {
 namespace detail {
 
 reactive_serial_port_service::reactive_serial_port_service(
-    boost::asio::io_service& io_service)
-  : descriptor_service_(io_service)
+    boost::asio::io_context& io_context)
+  : service_base<reactive_serial_port_service>(io_context),
+    descriptor_service_(io_context)
 {
 }
 
-void reactive_serial_port_service::shutdown_service()
+void reactive_serial_port_service::shutdown()
 {
-  descriptor_service_.shutdown_service();
+  descriptor_service_.shutdown();
 }
 
 boost::system::error_code reactive_serial_port_service::open(
diff --git a/include/boost/asio/detail/impl/reactive_socket_service_base.ipp b/include/boost/asio/detail/impl/reactive_socket_service_base.ipp
index 3594ae0528..23dbbb583c 100644
--- a/include/boost/asio/detail/impl/reactive_socket_service_base.ipp
+++ b/include/boost/asio/detail/impl/reactive_socket_service_base.ipp
@@ -29,13 +29,14 @@ namespace asio {
 namespace detail {
 
 reactive_socket_service_base::reactive_socket_service_base(
-    boost::asio::io_service& io_service)
-  : reactor_(use_service<reactor>(io_service))
+    boost::asio::io_context& io_context)
+  : io_context_(io_context),
+    reactor_(use_service<reactor>(io_context))
 {
   reactor_.init_task();
 }
 
-void reactive_socket_service_base::shutdown_service()
+void reactive_socket_service_base::base_shutdown()
 {
 }
 
@@ -82,7 +83,8 @@ void reactive_socket_service_base::destroy(
 {
   if (impl.socket_ != invalid_socket)
   {
-    BOOST_ASIO_HANDLER_OPERATION(("socket", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+          "socket", &impl, impl.socket_, "close"));
 
     reactor_.deregister_descriptor(impl.socket_, impl.reactor_data_,
         (impl.state_ & socket_ops::possible_dup) == 0);
@@ -100,7 +102,8 @@ boost::system::error_code reactive_socket_service_base::close(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("socket", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+          "socket", &impl, impl.socket_, "close"));
 
     reactor_.deregister_descriptor(impl.socket_, impl.reactor_data_,
         (impl.state_ & socket_ops::possible_dup) == 0);
@@ -127,6 +130,27 @@ boost::system::error_code reactive_socket_service_base::close(
   return ec;
 }
 
+socket_type reactive_socket_service_base::release(
+    reactive_socket_service_base::base_implementation_type& impl,
+    boost::system::error_code& ec)
+{
+  if (!is_open(impl))
+  {
+    ec = boost::asio::error::bad_descriptor;
+    return invalid_socket;
+  }
+
+  BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+        "socket", &impl, impl.socket_, "release"));
+
+  reactor_.deregister_descriptor(impl.socket_, impl.reactor_data_, false);
+  reactor_.cleanup_descriptor_data(impl.reactor_data_);
+  socket_type sock = impl.socket_;
+  construct(impl);
+  ec = boost::system::error_code();
+  return sock;
+}
+
 boost::system::error_code reactive_socket_service_base::cancel(
     reactive_socket_service_base::base_implementation_type& impl,
     boost::system::error_code& ec)
@@ -137,7 +161,8 @@ boost::system::error_code reactive_socket_service_base::cancel(
     return ec;
   }
 
-  BOOST_ASIO_HANDLER_OPERATION(("socket", &impl, "cancel"));
+  BOOST_ASIO_HANDLER_OPERATION((reactor_.context(),
+        "socket", &impl, impl.socket_, "cancel"));
 
   reactor_.cancel_ops(impl.socket_, impl.reactor_data_);
   ec = boost::system::error_code();
diff --git a/include/boost/asio/detail/impl/resolver_service_base.ipp b/include/boost/asio/detail/impl/resolver_service_base.ipp
index 4ef66cde15..1dbbd20c3f 100644
--- a/include/boost/asio/detail/impl/resolver_service_base.ipp
+++ b/include/boost/asio/detail/impl/resolver_service_base.ipp
@@ -24,62 +24,62 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-class resolver_service_base::work_io_service_runner
+class resolver_service_base::work_io_context_runner
 {
 public:
-  work_io_service_runner(boost::asio::io_service& io_service)
-    : io_service_(io_service) {}
-  void operator()() { io_service_.run(); }
+  work_io_context_runner(boost::asio::io_context& io_context)
+    : io_context_(io_context) {}
+  void operator()() { io_context_.run(); }
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
 };
 
 resolver_service_base::resolver_service_base(
-    boost::asio::io_service& io_service)
-  : io_service_impl_(boost::asio::use_service<io_service_impl>(io_service)),
-    work_io_service_(new boost::asio::io_service),
-    work_io_service_impl_(boost::asio::use_service<
-        io_service_impl>(*work_io_service_)),
-    work_(new boost::asio::io_service::work(*work_io_service_)),
+    boost::asio::io_context& io_context)
+  : io_context_impl_(boost::asio::use_service<io_context_impl>(io_context)),
+    work_io_context_(new boost::asio::io_context(-1)),
+    work_io_context_impl_(boost::asio::use_service<
+        io_context_impl>(*work_io_context_)),
+    work_(boost::asio::make_work_guard(*work_io_context_)),
     work_thread_(0)
 {
 }
 
 resolver_service_base::~resolver_service_base()
 {
-  shutdown_service();
+  base_shutdown();
 }
 
-void resolver_service_base::shutdown_service()
+void resolver_service_base::base_shutdown()
 {
   work_.reset();
-  if (work_io_service_.get())
+  if (work_io_context_.get())
   {
-    work_io_service_->stop();
+    work_io_context_->stop();
     if (work_thread_.get())
     {
       work_thread_->join();
       work_thread_.reset();
     }
-    work_io_service_.reset();
+    work_io_context_.reset();
   }
 }
 
-void resolver_service_base::fork_service(
-    boost::asio::io_service::fork_event fork_ev)
+void resolver_service_base::base_notify_fork(
+    boost::asio::io_context::fork_event fork_ev)
 {
   if (work_thread_.get())
   {
-    if (fork_ev == boost::asio::io_service::fork_prepare)
+    if (fork_ev == boost::asio::io_context::fork_prepare)
     {
-      work_io_service_->stop();
+      work_io_context_->stop();
       work_thread_->join();
     }
     else
     {
-      work_io_service_->reset();
+      work_io_context_->restart();
       work_thread_.reset(new boost::asio::detail::thread(
-            work_io_service_runner(*work_io_service_)));
+            work_io_context_runner(*work_io_context_)));
     }
   }
 }
@@ -93,24 +93,48 @@ void resolver_service_base::construct(
 void resolver_service_base::destroy(
     resolver_service_base::implementation_type& impl)
 {
-  BOOST_ASIO_HANDLER_OPERATION(("resolver", &impl, "cancel"));
+  BOOST_ASIO_HANDLER_OPERATION((io_context_impl_.context(),
+        "resolver", &impl, 0, "cancel"));
 
   impl.reset();
 }
 
+void resolver_service_base::move_construct(implementation_type& impl,
+    implementation_type& other_impl)
+{
+  impl = BOOST_ASIO_MOVE_CAST(implementation_type)(other_impl);
+}
+
+void resolver_service_base::move_assign(implementation_type& impl,
+    resolver_service_base&, implementation_type& other_impl)
+{
+  destroy(impl);
+  impl = BOOST_ASIO_MOVE_CAST(implementation_type)(other_impl);
+}
+
 void resolver_service_base::cancel(
     resolver_service_base::implementation_type& impl)
 {
-  BOOST_ASIO_HANDLER_OPERATION(("resolver", &impl, "cancel"));
+  BOOST_ASIO_HANDLER_OPERATION((io_context_impl_.context(),
+        "resolver", &impl, 0, "cancel"));
 
   impl.reset(static_cast<void*>(0), socket_ops::noop_deleter());
 }
 
-void resolver_service_base::start_resolve_op(operation* op)
+void resolver_service_base::start_resolve_op(resolve_op* op)
 {
-  start_work_thread();
-  io_service_impl_.work_started();
-  work_io_service_impl_.post_immediate_completion(op, false);
+  if (BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(SCHEDULER,
+        io_context_impl_.concurrency_hint()))
+  {
+    start_work_thread();
+    io_context_impl_.work_started();
+    work_io_context_impl_.post_immediate_completion(op, false);
+  }
+  else
+  {
+    op->ec_ = boost::asio::error::operation_not_supported;
+    io_context_impl_.post_immediate_completion(op, false);
+  }
 }
 
 void resolver_service_base::start_work_thread()
@@ -119,7 +143,7 @@ void resolver_service_base::start_work_thread()
   if (!work_thread_.get())
   {
     work_thread_.reset(new boost::asio::detail::thread(
-          work_io_service_runner(*work_io_service_)));
+          work_io_context_runner(*work_io_context_)));
   }
 }
 
diff --git a/include/boost/asio/detail/impl/task_io_service.ipp b/include/boost/asio/detail/impl/scheduler.ipp
similarity index 59%
rename from include/boost/asio/detail/impl/task_io_service.ipp
rename to include/boost/asio/detail/impl/scheduler.ipp
index bc83fd4757..7af3907016 100644
--- a/include/boost/asio/detail/impl/task_io_service.ipp
+++ b/include/boost/asio/detail/impl/scheduler.ipp
@@ -1,6 +1,6 @@
 //
-// detail/impl/task_io_service.ipp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// detail/impl/scheduler.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_IPP
-#define BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_IPP
+#ifndef BOOST_ASIO_DETAIL_IMPL_SCHEDULER_IPP
+#define BOOST_ASIO_DETAIL_IMPL_SCHEDULER_IPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -17,13 +17,12 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_HAS_IOCP)
-
+#include <boost/asio/detail/concurrency_hint.hpp>
 #include <boost/asio/detail/event.hpp>
 #include <boost/asio/detail/limits.hpp>
 #include <boost/asio/detail/reactor.hpp>
-#include <boost/asio/detail/task_io_service.hpp>
-#include <boost/asio/detail/task_io_service_thread_info.hpp>
+#include <boost/asio/detail/scheduler.hpp>
+#include <boost/asio/detail/scheduler_thread_info.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -31,14 +30,14 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-struct task_io_service::task_cleanup
+struct scheduler::task_cleanup
 {
   ~task_cleanup()
   {
     if (this_thread_->private_outstanding_work > 0)
     {
       boost::asio::detail::increment(
-          task_io_service_->outstanding_work_,
+          scheduler_->outstanding_work_,
           this_thread_->private_outstanding_work);
     }
     this_thread_->private_outstanding_work = 0;
@@ -46,29 +45,29 @@ struct task_io_service::task_cleanup
     // Enqueue the completed operations and reinsert the task at the end of
     // the operation queue.
     lock_->lock();
-    task_io_service_->task_interrupted_ = true;
-    task_io_service_->op_queue_.push(this_thread_->private_op_queue);
-    task_io_service_->op_queue_.push(&task_io_service_->task_operation_);
+    scheduler_->task_interrupted_ = true;
+    scheduler_->op_queue_.push(this_thread_->private_op_queue);
+    scheduler_->op_queue_.push(&scheduler_->task_operation_);
   }
 
-  task_io_service* task_io_service_;
+  scheduler* scheduler_;
   mutex::scoped_lock* lock_;
   thread_info* this_thread_;
 };
 
-struct task_io_service::work_cleanup
+struct scheduler::work_cleanup
 {
   ~work_cleanup()
   {
     if (this_thread_->private_outstanding_work > 1)
     {
       boost::asio::detail::increment(
-          task_io_service_->outstanding_work_,
+          scheduler_->outstanding_work_,
           this_thread_->private_outstanding_work - 1);
     }
     else if (this_thread_->private_outstanding_work < 1)
     {
-      task_io_service_->work_finished();
+      scheduler_->work_finished();
     }
     this_thread_->private_outstanding_work = 0;
 
@@ -76,31 +75,37 @@ struct task_io_service::work_cleanup
     if (!this_thread_->private_op_queue.empty())
     {
       lock_->lock();
-      task_io_service_->op_queue_.push(this_thread_->private_op_queue);
+      scheduler_->op_queue_.push(this_thread_->private_op_queue);
     }
 #endif // defined(BOOST_ASIO_HAS_THREADS)
   }
 
-  task_io_service* task_io_service_;
+  scheduler* scheduler_;
   mutex::scoped_lock* lock_;
   thread_info* this_thread_;
 };
 
-task_io_service::task_io_service(
-    boost::asio::io_service& io_service, std::size_t concurrency_hint)
-  : boost::asio::detail::service_base<task_io_service>(io_service),
-    one_thread_(concurrency_hint == 1),
-    mutex_(),
+scheduler::scheduler(
+    boost::asio::execution_context& ctx, int concurrency_hint)
+  : boost::asio::detail::execution_context_service_base<scheduler>(ctx),
+    one_thread_(concurrency_hint == 1
+        || !BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(
+          SCHEDULER, concurrency_hint)
+        || !BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(
+          REACTOR_IO, concurrency_hint)),
+    mutex_(BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(
+          SCHEDULER, concurrency_hint)),
     task_(0),
     task_interrupted_(true),
     outstanding_work_(0),
     stopped_(false),
-    shutdown_(false)
+    shutdown_(false),
+    concurrency_hint_(concurrency_hint)
 {
   BOOST_ASIO_HANDLER_TRACKING_INIT;
 }
 
-void task_io_service::shutdown_service()
+void scheduler::shutdown()
 {
   mutex::scoped_lock lock(mutex_);
   shutdown_ = true;
@@ -119,18 +124,18 @@ void task_io_service::shutdown_service()
   task_ = 0;
 }
 
-void task_io_service::init_task()
+void scheduler::init_task()
 {
   mutex::scoped_lock lock(mutex_);
   if (!shutdown_ && !task_)
   {
-    task_ = &use_service<reactor>(this->get_io_service());
+    task_ = &use_service<reactor>(this->context());
     op_queue_.push(&task_operation_);
     wake_one_thread_and_unlock(lock);
   }
 }
 
-std::size_t task_io_service::run(boost::system::error_code& ec)
+std::size_t scheduler::run(boost::system::error_code& ec)
 {
   ec = boost::system::error_code();
   if (outstanding_work_ == 0)
@@ -152,7 +157,7 @@ std::size_t task_io_service::run(boost::system::error_code& ec)
   return n;
 }
 
-std::size_t task_io_service::run_one(boost::system::error_code& ec)
+std::size_t scheduler::run_one(boost::system::error_code& ec)
 {
   ec = boost::system::error_code();
   if (outstanding_work_ == 0)
@@ -170,7 +175,25 @@ std::size_t task_io_service::run_one(boost::system::error_code& ec)
   return do_run_one(lock, this_thread, ec);
 }
 
-std::size_t task_io_service::poll(boost::system::error_code& ec)
+std::size_t scheduler::wait_one(long usec, boost::system::error_code& ec)
+{
+  ec = boost::system::error_code();
+  if (outstanding_work_ == 0)
+  {
+    stop();
+    return 0;
+  }
+
+  thread_info this_thread;
+  this_thread.private_outstanding_work = 0;
+  thread_call_stack::context ctx(this, this_thread);
+
+  mutex::scoped_lock lock(mutex_);
+
+  return do_wait_one(lock, this_thread, usec, ec);
+}
+
+std::size_t scheduler::poll(boost::system::error_code& ec)
 {
   ec = boost::system::error_code();
   if (outstanding_work_ == 0)
@@ -190,8 +213,8 @@ std::size_t task_io_service::poll(boost::system::error_code& ec)
   // that are already on a thread-private queue need to be put on to the main
   // queue now.
   if (one_thread_)
-    if (thread_info* outer_thread_info = ctx.next_by_key())
-      op_queue_.push(outer_thread_info->private_op_queue);
+    if (thread_info* outer_info = static_cast<thread_info*>(ctx.next_by_key()))
+      op_queue_.push(outer_info->private_op_queue);
 #endif // defined(BOOST_ASIO_HAS_THREADS)
 
   std::size_t n = 0;
@@ -201,7 +224,7 @@ std::size_t task_io_service::poll(boost::system::error_code& ec)
   return n;
 }
 
-std::size_t task_io_service::poll_one(boost::system::error_code& ec)
+std::size_t scheduler::poll_one(boost::system::error_code& ec)
 {
   ec = boost::system::error_code();
   if (outstanding_work_ == 0)
@@ -221,41 +244,47 @@ std::size_t task_io_service::poll_one(boost::system::error_code& ec)
   // that are already on a thread-private queue need to be put on to the main
   // queue now.
   if (one_thread_)
-    if (thread_info* outer_thread_info = ctx.next_by_key())
-      op_queue_.push(outer_thread_info->private_op_queue);
+    if (thread_info* outer_info = static_cast<thread_info*>(ctx.next_by_key()))
+      op_queue_.push(outer_info->private_op_queue);
 #endif // defined(BOOST_ASIO_HAS_THREADS)
 
   return do_poll_one(lock, this_thread, ec);
 }
 
-void task_io_service::stop()
+void scheduler::stop()
 {
   mutex::scoped_lock lock(mutex_);
   stop_all_threads(lock);
 }
 
-bool task_io_service::stopped() const
+bool scheduler::stopped() const
 {
   mutex::scoped_lock lock(mutex_);
   return stopped_;
 }
 
-void task_io_service::reset()
+void scheduler::restart()
 {
   mutex::scoped_lock lock(mutex_);
   stopped_ = false;
 }
 
-void task_io_service::post_immediate_completion(
-    task_io_service::operation* op, bool is_continuation)
+void scheduler::compensating_work_started()
+{
+  thread_info_base* this_thread = thread_call_stack::contains(this);
+  ++static_cast<thread_info*>(this_thread)->private_outstanding_work;
+}
+
+void scheduler::post_immediate_completion(
+    scheduler::operation* op, bool is_continuation)
 {
 #if defined(BOOST_ASIO_HAS_THREADS)
   if (one_thread_ || is_continuation)
   {
-    if (thread_info* this_thread = thread_call_stack::contains(this))
+    if (thread_info_base* this_thread = thread_call_stack::contains(this))
     {
-      ++this_thread->private_outstanding_work;
-      this_thread->private_op_queue.push(op);
+      ++static_cast<thread_info*>(this_thread)->private_outstanding_work;
+      static_cast<thread_info*>(this_thread)->private_op_queue.push(op);
       return;
     }
   }
@@ -269,14 +298,14 @@ void task_io_service::post_immediate_completion(
   wake_one_thread_and_unlock(lock);
 }
 
-void task_io_service::post_deferred_completion(task_io_service::operation* op)
+void scheduler::post_deferred_completion(scheduler::operation* op)
 {
 #if defined(BOOST_ASIO_HAS_THREADS)
   if (one_thread_)
   {
-    if (thread_info* this_thread = thread_call_stack::contains(this))
+    if (thread_info_base* this_thread = thread_call_stack::contains(this))
     {
-      this_thread->private_op_queue.push(op);
+      static_cast<thread_info*>(this_thread)->private_op_queue.push(op);
       return;
     }
   }
@@ -287,17 +316,17 @@ void task_io_service::post_deferred_completion(task_io_service::operation* op)
   wake_one_thread_and_unlock(lock);
 }
 
-void task_io_service::post_deferred_completions(
-    op_queue<task_io_service::operation>& ops)
+void scheduler::post_deferred_completions(
+    op_queue<scheduler::operation>& ops)
 {
   if (!ops.empty())
   {
 #if defined(BOOST_ASIO_HAS_THREADS)
     if (one_thread_)
     {
-      if (thread_info* this_thread = thread_call_stack::contains(this))
+      if (thread_info_base* this_thread = thread_call_stack::contains(this))
       {
-        this_thread->private_op_queue.push(ops);
+        static_cast<thread_info*>(this_thread)->private_op_queue.push(ops);
         return;
       }
     }
@@ -309,8 +338,8 @@ void task_io_service::post_deferred_completions(
   }
 }
 
-void task_io_service::do_dispatch(
-    task_io_service::operation* op)
+void scheduler::do_dispatch(
+    scheduler::operation* op)
 {
   work_started();
   mutex::scoped_lock lock(mutex_);
@@ -318,15 +347,15 @@ void task_io_service::do_dispatch(
   wake_one_thread_and_unlock(lock);
 }
 
-void task_io_service::abandon_operations(
-    op_queue<task_io_service::operation>& ops)
+void scheduler::abandon_operations(
+    op_queue<scheduler::operation>& ops)
 {
-  op_queue<task_io_service::operation> ops2;
+  op_queue<scheduler::operation> ops2;
   ops2.push(ops);
 }
 
-std::size_t task_io_service::do_run_one(mutex::scoped_lock& lock,
-    task_io_service::thread_info& this_thread,
+std::size_t scheduler::do_run_one(mutex::scoped_lock& lock,
+    scheduler::thread_info& this_thread,
     const boost::system::error_code& ec)
 {
   while (!stopped_)
@@ -353,7 +382,7 @@ std::size_t task_io_service::do_run_one(mutex::scoped_lock& lock,
         // Run the task. May throw an exception. Only block if the operation
         // queue is empty and we're not polling, otherwise we want to return
         // as soon as possible.
-        task_->run(!more_handlers, this_thread.private_op_queue);
+        task_->run(more_handlers ? 0 : -1, this_thread.private_op_queue);
       }
       else
       {
@@ -369,7 +398,7 @@ std::size_t task_io_service::do_run_one(mutex::scoped_lock& lock,
         (void)on_exit;
 
         // Complete the operation. May throw an exception. Deletes the object.
-        o->complete(*this, ec, task_result);
+        o->complete(this, ec, task_result);
 
         return 1;
       }
@@ -384,8 +413,78 @@ std::size_t task_io_service::do_run_one(mutex::scoped_lock& lock,
   return 0;
 }
 
-std::size_t task_io_service::do_poll_one(mutex::scoped_lock& lock,
-    task_io_service::thread_info& this_thread,
+std::size_t scheduler::do_wait_one(mutex::scoped_lock& lock,
+    scheduler::thread_info& this_thread, long usec,
+    const boost::system::error_code& ec)
+{
+  if (stopped_)
+    return 0;
+
+  operation* o = op_queue_.front();
+  if (o == 0)
+  {
+    wakeup_event_.clear(lock);
+    wakeup_event_.wait_for_usec(lock, usec);
+    usec = 0; // Wait at most once.
+    o = op_queue_.front();
+  }
+
+  if (o == &task_operation_)
+  {
+    op_queue_.pop();
+    bool more_handlers = (!op_queue_.empty());
+
+    task_interrupted_ = more_handlers;
+
+    if (more_handlers && !one_thread_)
+      wakeup_event_.unlock_and_signal_one(lock);
+    else
+      lock.unlock();
+
+    {
+      task_cleanup on_exit = { this, &lock, &this_thread };
+      (void)on_exit;
+
+      // Run the task. May throw an exception. Only block if the operation
+      // queue is empty and we're not polling, otherwise we want to return
+      // as soon as possible.
+      task_->run(more_handlers ? 0 : usec, this_thread.private_op_queue);
+    }
+
+    o = op_queue_.front();
+    if (o == &task_operation_)
+    {
+      if (!one_thread_)
+        wakeup_event_.maybe_unlock_and_signal_one(lock);
+      return 0;
+    }
+  }
+
+  if (o == 0)
+    return 0;
+
+  op_queue_.pop();
+  bool more_handlers = (!op_queue_.empty());
+
+  std::size_t task_result = o->task_result_;
+
+  if (more_handlers && !one_thread_)
+    wake_one_thread_and_unlock(lock);
+  else
+    lock.unlock();
+
+  // Ensure the count of outstanding work is decremented on block exit.
+  work_cleanup on_exit = { this, &lock, &this_thread };
+  (void)on_exit;
+
+  // Complete the operation. May throw an exception. Deletes the object.
+  o->complete(this, ec, task_result);
+
+  return 1;
+}
+
+std::size_t scheduler::do_poll_one(mutex::scoped_lock& lock,
+    scheduler::thread_info& this_thread,
     const boost::system::error_code& ec)
 {
   if (stopped_)
@@ -404,7 +503,7 @@ std::size_t task_io_service::do_poll_one(mutex::scoped_lock& lock,
       // Run the task. May throw an exception. Only block if the operation
       // queue is empty and we're not polling, otherwise we want to return
       // as soon as possible.
-      task_->run(false, this_thread.private_op_queue);
+      task_->run(0, this_thread.private_op_queue);
     }
 
     o = op_queue_.front();
@@ -433,12 +532,12 @@ std::size_t task_io_service::do_poll_one(mutex::scoped_lock& lock,
   (void)on_exit;
 
   // Complete the operation. May throw an exception. Deletes the object.
-  o->complete(*this, ec, task_result);
+  o->complete(this, ec, task_result);
 
   return 1;
 }
 
-void task_io_service::stop_all_threads(
+void scheduler::stop_all_threads(
     mutex::scoped_lock& lock)
 {
   stopped_ = true;
@@ -451,7 +550,7 @@ void task_io_service::stop_all_threads(
   }
 }
 
-void task_io_service::wake_one_thread_and_unlock(
+void scheduler::wake_one_thread_and_unlock(
     mutex::scoped_lock& lock)
 {
   if (!wakeup_event_.maybe_unlock_and_signal_one(lock))
@@ -471,6 +570,4 @@ void task_io_service::wake_one_thread_and_unlock(
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#endif // !defined(BOOST_ASIO_HAS_IOCP)
-
-#endif // BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_IPP
+#endif // BOOST_ASIO_DETAIL_IMPL_SCHEDULER_IPP
diff --git a/include/boost/asio/detail/impl/select_reactor.hpp b/include/boost/asio/detail/impl/select_reactor.hpp
index d3f28f5e61..207a045f6c 100644
--- a/include/boost/asio/detail/impl/select_reactor.hpp
+++ b/include/boost/asio/detail/impl/select_reactor.hpp
@@ -51,12 +51,12 @@ void select_reactor::schedule_timer(timer_queue<Time_Traits>& queue,
 
   if (shutdown_)
   {
-    io_service_.post_immediate_completion(op, false);
+    scheduler_.post_immediate_completion(op, false);
     return;
   }
 
   bool earliest = queue.enqueue_timer(time, timer, op);
-  io_service_.work_started();
+  scheduler_.work_started();
   if (earliest)
     interrupter_.interrupt();
 }
@@ -70,10 +70,23 @@ std::size_t select_reactor::cancel_timer(timer_queue<Time_Traits>& queue,
   op_queue<operation> ops;
   std::size_t n = queue.cancel_timer(timer, ops, max_cancelled);
   lock.unlock();
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
   return n;
 }
 
+template <typename Time_Traits>
+void select_reactor::move_timer(timer_queue<Time_Traits>& queue,
+    typename timer_queue<Time_Traits>::per_timer_data& target,
+    typename timer_queue<Time_Traits>::per_timer_data& source)
+{
+  boost::asio::detail::mutex::scoped_lock lock(mutex_);
+  op_queue<operation> ops;
+  queue.cancel_timer(target, ops);
+  queue.move_timer(target, source);
+  lock.unlock();
+  scheduler_.post_deferred_completions(ops);
+}
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/detail/impl/select_reactor.ipp b/include/boost/asio/detail/impl/select_reactor.ipp
index 869f73492b..44fab64269 100644
--- a/include/boost/asio/detail/impl/select_reactor.ipp
+++ b/include/boost/asio/detail/impl/select_reactor.ipp
@@ -23,7 +23,6 @@
       && !defined(BOOST_ASIO_HAS_KQUEUE) \
       && !defined(BOOST_ASIO_WINDOWS_RUNTIME))
 
-#include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/fd_set_adapter.hpp>
 #include <boost/asio/detail/select_reactor.hpp>
 #include <boost/asio/detail/signal_blocker.hpp>
@@ -35,9 +34,28 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-select_reactor::select_reactor(boost::asio::io_service& io_service)
-  : boost::asio::detail::service_base<select_reactor>(io_service),
-    io_service_(use_service<io_service_impl>(io_service)),
+#if defined(BOOST_ASIO_HAS_IOCP)
+class select_reactor::thread_function
+{
+public:
+  explicit thread_function(select_reactor* r)
+    : this_(r)
+  {
+  }
+
+  void operator()()
+  {
+    this_->run_thread();
+  }
+
+private:
+  select_reactor* this_;
+};
+#endif // defined(BOOST_ASIO_HAS_IOCP)
+
+select_reactor::select_reactor(boost::asio::execution_context& ctx)
+  : execution_context_service_base<select_reactor>(ctx),
+    scheduler_(use_service<scheduler_type>(ctx)),
     mutex_(),
     interrupter_(),
 #if defined(BOOST_ASIO_HAS_IOCP)
@@ -48,17 +66,16 @@ select_reactor::select_reactor(boost::asio::io_service& io_service)
 {
 #if defined(BOOST_ASIO_HAS_IOCP)
   boost::asio::detail::signal_blocker sb;
-  thread_ = new boost::asio::detail::thread(
-      bind_handler(&select_reactor::call_run_thread, this));
+  thread_ = new boost::asio::detail::thread(thread_function(this));
 #endif // defined(BOOST_ASIO_HAS_IOCP)
 }
 
 select_reactor::~select_reactor()
 {
-  shutdown_service();
+  shutdown();
 }
 
-void select_reactor::shutdown_service()
+void select_reactor::shutdown()
 {
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
   shutdown_ = true;
@@ -84,18 +101,19 @@ void select_reactor::shutdown_service()
 
   timer_queues_.get_all_timers(ops);
 
-  io_service_.abandon_operations(ops);
+  scheduler_.abandon_operations(ops);
 }
 
-void select_reactor::fork_service(boost::asio::io_service::fork_event fork_ev)
+void select_reactor::notify_fork(
+    boost::asio::execution_context::fork_event fork_ev)
 {
-  if (fork_ev == boost::asio::io_service::fork_child)
+  if (fork_ev == boost::asio::execution_context::fork_child)
     interrupter_.recreate();
 }
 
 void select_reactor::init_task()
 {
-  io_service_.init_task();
+  scheduler_.init_task();
 }
 
 int select_reactor::register_descriptor(socket_type,
@@ -135,7 +153,7 @@ void select_reactor::start_op(int op_type, socket_type descriptor,
   }
 
   bool first = op_queue_[op_type].enqueue_operation(descriptor, op);
-  io_service_.work_started();
+  scheduler_.work_started();
   if (first)
     interrupter_.interrupt();
 }
@@ -168,7 +186,7 @@ void select_reactor::cleanup_descriptor_data(
 {
 }
 
-void select_reactor::run(bool block, op_queue<operation>& ops)
+void select_reactor::run(long usec, op_queue<operation>& ops)
 {
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
 
@@ -205,12 +223,12 @@ void select_reactor::run(bool block, op_queue<operation>& ops)
 
   // We can return immediately if there's no work to do and the reactor is
   // not supposed to block.
-  if (!block && !have_work_to_do)
+  if (!usec && !have_work_to_do)
     return;
 
   // Determine how long to block while waiting for events.
   timeval tv_buf = { 0, 0 };
-  timeval* tv = block ? get_timeout(tv_buf) : &tv_buf;
+  timeval* tv = usec ? get_timeout(usec, tv_buf) : &tv_buf;
 
   lock.unlock();
 
@@ -259,15 +277,10 @@ void select_reactor::run_thread()
     lock.unlock();
     op_queue<operation> ops;
     run(true, ops);
-    io_service_.post_deferred_completions(ops);
+    scheduler_.post_deferred_completions(ops);
     lock.lock();
   }
 }
-
-void select_reactor::call_run_thread(select_reactor* reactor)
-{
-  reactor->run_thread();
-}
 #endif // defined(BOOST_ASIO_HAS_IOCP)
 
 void select_reactor::do_add_timer_queue(timer_queue_base& queue)
@@ -282,11 +295,13 @@ void select_reactor::do_remove_timer_queue(timer_queue_base& queue)
   timer_queues_.erase(&queue);
 }
 
-timeval* select_reactor::get_timeout(timeval& tv)
+timeval* select_reactor::get_timeout(long usec, timeval& tv)
 {
   // By default we will wait no longer than 5 minutes. This will ensure that
   // any changes to the system clock are detected after no longer than this.
-  long usec = timer_queues_.wait_duration_usec(5 * 60 * 1000 * 1000);
+  const long max_usec = 5 * 60 * 1000 * 1000;
+  usec = timer_queues_.wait_duration_usec(
+      (usec < 0 || max_usec < usec) ? max_usec : usec);
   tv.tv_sec = usec / 1000000;
   tv.tv_usec = usec % 1000000;
   return &tv;
@@ -300,7 +315,7 @@ void select_reactor::cancel_ops_unlocked(socket_type descriptor,
   for (int i = 0; i < max_ops; ++i)
     need_interrupt = op_queue_[i].cancel_operations(
         descriptor, ops, ec) || need_interrupt;
-  io_service_.post_deferred_completions(ops);
+  scheduler_.post_deferred_completions(ops);
   if (need_interrupt)
     interrupter_.interrupt();
 }
diff --git a/include/boost/asio/detail/impl/service_registry.hpp b/include/boost/asio/detail/impl/service_registry.hpp
index 7ffdd029f7..11ad4cf5cc 100644
--- a/include/boost/asio/detail/impl/service_registry.hpp
+++ b/include/boost/asio/detail/impl/service_registry.hpp
@@ -21,64 +21,70 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-template <typename Service, typename Arg>
-service_registry::service_registry(
-    boost::asio::io_service& o, Service*, Arg arg)
-  : owner_(o),
-    first_service_(new Service(o, arg))
-{
-  boost::asio::io_service::service::key key;
-  init_key(key, Service::id);
-  first_service_->key_ = key;
-  first_service_->next_ = 0;
-}
-
 template <typename Service>
-Service& service_registry::first_service()
+Service& service_registry::use_service()
 {
-  return *static_cast<Service*>(first_service_);
+  execution_context::service::key key;
+  init_key<Service>(key, 0);
+  factory_type factory = &service_registry::create<Service, execution_context>;
+  return *static_cast<Service*>(do_use_service(key, factory, &owner_));
 }
 
 template <typename Service>
-Service& service_registry::use_service()
+Service& service_registry::use_service(io_context& owner)
 {
-  boost::asio::io_service::service::key key;
-  init_key(key, Service::id);
-  factory_type factory = &service_registry::create<Service>;
-  return *static_cast<Service*>(do_use_service(key, factory));
+  execution_context::service::key key;
+  init_key<Service>(key, 0);
+  factory_type factory = &service_registry::create<Service, io_context>;
+  return *static_cast<Service*>(do_use_service(key, factory, &owner));
 }
 
 template <typename Service>
 void service_registry::add_service(Service* new_service)
 {
-  boost::asio::io_service::service::key key;
-  init_key(key, Service::id);
+  execution_context::service::key key;
+  init_key<Service>(key, 0);
   return do_add_service(key, new_service);
 }
 
 template <typename Service>
 bool service_registry::has_service() const
 {
-  boost::asio::io_service::service::key key;
-  init_key(key, Service::id);
+  execution_context::service::key key;
+  init_key<Service>(key, 0);
   return do_has_service(key);
 }
 
+template <typename Service>
+inline void service_registry::init_key(
+    execution_context::service::key& key, ...)
+{
+  init_key_from_id(key, Service::id);
+}
+
 #if !defined(BOOST_ASIO_NO_TYPEID)
 template <typename Service>
-void service_registry::init_key(boost::asio::io_service::service::key& key,
-    const boost::asio::detail::service_id<Service>& /*id*/)
+void service_registry::init_key(execution_context::service::key& key,
+    typename enable_if<
+      is_base_of<typename Service::key_type, Service>::value>::type*)
 {
   key.type_info_ = &typeid(typeid_wrapper<Service>);
   key.id_ = 0;
 }
-#endif // !defined(BOOST_ASIO_NO_TYPEID)
 
 template <typename Service>
-boost::asio::io_service::service* service_registry::create(
-    boost::asio::io_service& owner)
+void service_registry::init_key_from_id(execution_context::service::key& key,
+    const service_id<Service>& /*id*/)
+{
+  key.type_info_ = &typeid(typeid_wrapper<Service>);
+  key.id_ = 0;
+}
+#endif // !defined(BOOST_ASIO_NO_TYPEID)
+
+template <typename Service, typename Owner>
+execution_context::service* service_registry::create(void* owner)
 {
-  return new Service(owner);
+  return new Service(*static_cast<Owner*>(owner));
 }
 
 } // namespace detail
diff --git a/include/boost/asio/detail/impl/service_registry.ipp b/include/boost/asio/detail/impl/service_registry.ipp
index 25ac8eccc6..75c3f45625 100644
--- a/include/boost/asio/detail/impl/service_registry.ipp
+++ b/include/boost/asio/detail/impl/service_registry.ipp
@@ -26,36 +26,45 @@ namespace boost {
 namespace asio {
 namespace detail {
 
+service_registry::service_registry(execution_context& owner)
+  : owner_(owner),
+    first_service_(0)
+{
+}
+
 service_registry::~service_registry()
 {
-  // Shutdown all services. This must be done in a separate loop before the
-  // services are destroyed since the destructors of user-defined handler
-  // objects may try to access other service objects.
-  boost::asio::io_service::service* service = first_service_;
+}
+
+void service_registry::shutdown_services()
+{
+  execution_context::service* service = first_service_;
   while (service)
   {
-    service->shutdown_service();
+    service->shutdown();
     service = service->next_;
   }
+}
 
-  // Destroy all services.
+void service_registry::destroy_services()
+{
   while (first_service_)
   {
-    boost::asio::io_service::service* next_service = first_service_->next_;
+    execution_context::service* next_service = first_service_->next_;
     destroy(first_service_);
     first_service_ = next_service;
   }
 }
 
-void service_registry::notify_fork(boost::asio::io_service::fork_event fork_ev)
+void service_registry::notify_fork(execution_context::fork_event fork_ev)
 {
   // Make a copy of all of the services while holding the lock. We don't want
   // to hold the lock while calling into each service, as it may try to call
   // back into this class.
-  std::vector<boost::asio::io_service::service*> services;
+  std::vector<execution_context::service*> services;
   {
     boost::asio::detail::mutex::scoped_lock lock(mutex_);
-    boost::asio::io_service::service* service = first_service_;
+    execution_context::service* service = first_service_;
     while (service)
     {
       services.push_back(service);
@@ -68,24 +77,24 @@ void service_registry::notify_fork(boost::asio::io_service::fork_event fork_ev)
   // services in the vector. For the other events we want to go in the other
   // direction.
   std::size_t num_services = services.size();
-  if (fork_ev == boost::asio::io_service::fork_prepare)
+  if (fork_ev == execution_context::fork_prepare)
     for (std::size_t i = 0; i < num_services; ++i)
-      services[i]->fork_service(fork_ev);
+      services[i]->notify_fork(fork_ev);
   else
     for (std::size_t i = num_services; i > 0; --i)
-      services[i - 1]->fork_service(fork_ev);
+      services[i - 1]->notify_fork(fork_ev);
 }
 
-void service_registry::init_key(boost::asio::io_service::service::key& key,
-    const boost::asio::io_service::id& id)
+void service_registry::init_key_from_id(execution_context::service::key& key,
+    const execution_context::id& id)
 {
   key.type_info_ = 0;
   key.id_ = &id;
 }
 
 bool service_registry::keys_match(
-    const boost::asio::io_service::service::key& key1,
-    const boost::asio::io_service::service::key& key2)
+    const execution_context::service::key& key1,
+    const execution_context::service::key& key2)
 {
   if (key1.id_ && key2.id_)
     if (key1.id_ == key2.id_)
@@ -96,19 +105,19 @@ bool service_registry::keys_match(
   return false;
 }
 
-void service_registry::destroy(boost::asio::io_service::service* service)
+void service_registry::destroy(execution_context::service* service)
 {
   delete service;
 }
 
-boost::asio::io_service::service* service_registry::do_use_service(
-    const boost::asio::io_service::service::key& key,
-    factory_type factory)
+execution_context::service* service_registry::do_use_service(
+    const execution_context::service::key& key,
+    factory_type factory, void* owner)
 {
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
 
   // First see if there is an existing service object with the given key.
-  boost::asio::io_service::service* service = first_service_;
+  execution_context::service* service = first_service_;
   while (service)
   {
     if (keys_match(service->key_, key))
@@ -120,7 +129,7 @@ boost::asio::io_service::service* service_registry::do_use_service(
   // at this time to allow for nested calls into this function from the new
   // service's constructor.
   lock.unlock();
-  auto_service_ptr new_service = { factory(owner_) };
+  auto_service_ptr new_service = { factory(owner) };
   new_service.ptr_->key_ = key;
   lock.lock();
 
@@ -142,16 +151,16 @@ boost::asio::io_service::service* service_registry::do_use_service(
 }
 
 void service_registry::do_add_service(
-    const boost::asio::io_service::service::key& key,
-    boost::asio::io_service::service* new_service)
+    const execution_context::service::key& key,
+    execution_context::service* new_service)
 {
-  if (&owner_ != &new_service->get_io_service())
+  if (&owner_ != &new_service->context())
     boost::asio::detail::throw_exception(invalid_service_owner());
 
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
 
   // Check if there is an existing service object with the given key.
-  boost::asio::io_service::service* service = first_service_;
+  execution_context::service* service = first_service_;
   while (service)
   {
     if (keys_match(service->key_, key))
@@ -166,11 +175,11 @@ void service_registry::do_add_service(
 }
 
 bool service_registry::do_has_service(
-    const boost::asio::io_service::service::key& key) const
+    const execution_context::service::key& key) const
 {
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
 
-  boost::asio::io_service::service* service = first_service_;
+  execution_context::service* service = first_service_;
   while (service)
   {
     if (keys_match(service->key_, key))
diff --git a/include/boost/asio/detail/impl/signal_set_service.ipp b/include/boost/asio/detail/impl/signal_set_service.ipp
index 95ea8bee21..376d311471 100644
--- a/include/boost/asio/detail/impl/signal_set_service.ipp
+++ b/include/boost/asio/detail/impl/signal_set_service.ipp
@@ -18,10 +18,12 @@
 #include <boost/asio/detail/config.hpp>
 
 #include <cstring>
+#include <stdexcept>
 #include <boost/asio/detail/reactor.hpp>
 #include <boost/asio/detail/signal_blocker.hpp>
 #include <boost/asio/detail/signal_set_service.hpp>
 #include <boost/asio/detail/static_mutex.hpp>
+#include <boost/asio/detail/throw_exception.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -92,7 +94,7 @@ public:
   {
   }
 
-  static bool do_perform(reactor_op*)
+  static status do_perform(reactor_op*)
   {
     signal_state* state = get_signal_state();
 
@@ -102,10 +104,10 @@ public:
       if (signal_number >= 0 && signal_number < max_signal_number)
         signal_set_service::deliver_signal(signal_number);
 
-    return false;
+    return not_done;
   }
 
-  static void do_complete(io_service_impl* /*owner*/, operation* base,
+  static void do_complete(void* /*owner*/, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
@@ -118,12 +120,13 @@ public:
        //   && !defined(__CYGWIN__)
 
 signal_set_service::signal_set_service(
-    boost::asio::io_service& io_service)
-  : io_service_(boost::asio::use_service<io_service_impl>(io_service)),
+    boost::asio::io_context& io_context)
+  : service_base<signal_set_service>(io_context),
+    io_context_(boost::asio::use_service<io_context_impl>(io_context)),
 #if !defined(BOOST_ASIO_WINDOWS) \
   && !defined(BOOST_ASIO_WINDOWS_RUNTIME) \
   && !defined(__CYGWIN__)
-    reactor_(boost::asio::use_service<reactor>(io_service)),
+    reactor_(boost::asio::use_service<reactor>(io_context)),
 #endif // !defined(BOOST_ASIO_WINDOWS)
        //   && !defined(BOOST_ASIO_WINDOWS_RUNTIME)
        //   && !defined(__CYGWIN__)
@@ -151,7 +154,7 @@ signal_set_service::~signal_set_service()
   remove_service(this);
 }
 
-void signal_set_service::shutdown_service()
+void signal_set_service::shutdown()
 {
   remove_service(this);
 
@@ -167,11 +170,11 @@ void signal_set_service::shutdown_service()
     }
   }
 
-  io_service_.abandon_operations(ops);
+  io_context_.abandon_operations(ops);
 }
 
-void signal_set_service::fork_service(
-    boost::asio::io_service::fork_event fork_ev)
+void signal_set_service::notify_fork(
+    boost::asio::io_context::fork_event fork_ev)
 {
 #if !defined(BOOST_ASIO_WINDOWS) \
   && !defined(BOOST_ASIO_WINDOWS_RUNTIME) \
@@ -181,7 +184,7 @@ void signal_set_service::fork_service(
 
   switch (fork_ev)
   {
-  case boost::asio::io_service::fork_prepare:
+  case boost::asio::io_context::fork_prepare:
     {
       int read_descriptor = state->read_descriptor_;
       state->fork_prepared_ = true;
@@ -190,7 +193,7 @@ void signal_set_service::fork_service(
       reactor_.cleanup_descriptor_data(reactor_data_);
     }
     break;
-  case boost::asio::io_service::fork_parent:
+  case boost::asio::io_context::fork_parent:
     if (state->fork_prepared_)
     {
       int read_descriptor = state->read_descriptor_;
@@ -200,7 +203,7 @@ void signal_set_service::fork_service(
           read_descriptor, reactor_data_, new pipe_read_op);
     }
     break;
-  case boost::asio::io_service::fork_child:
+  case boost::asio::io_context::fork_child:
     if (state->fork_prepared_)
     {
       boost::asio::detail::signal_blocker blocker;
@@ -439,7 +442,8 @@ boost::system::error_code signal_set_service::cancel(
     signal_set_service::implementation_type& impl,
     boost::system::error_code& ec)
 {
-  BOOST_ASIO_HANDLER_OPERATION(("signal_set", &impl, "cancel"));
+  BOOST_ASIO_HANDLER_OPERATION((io_context_.context(),
+        "signal_set", &impl, 0, "cancel"));
 
   op_queue<operation> ops;
   {
@@ -454,7 +458,7 @@ boost::system::error_code signal_set_service::cancel(
     }
   }
 
-  io_service_.post_deferred_completions(ops);
+  io_context_.post_deferred_completions(ops);
 
   ec = boost::system::error_code();
   return ec;
@@ -490,7 +494,7 @@ void signal_set_service::deliver_signal(int signal_number)
       reg = reg->next_in_table_;
     }
 
-    service->io_service_.post_deferred_completions(ops);
+    service->io_context_.post_deferred_completions(ops);
 
     service = service->next_;
   }
@@ -507,6 +511,22 @@ void signal_set_service::add_service(signal_set_service* service)
     open_descriptors();
 #endif // !defined(BOOST_ASIO_WINDOWS) && !defined(__CYGWIN__)
 
+  // If an io_context object is thread-unsafe then it must be the only
+  // io_context used to create signal_set objects.
+  if (state->service_list_ != 0)
+  {
+    if (!BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(SCHEDULER,
+          service->io_context_.concurrency_hint())
+        || !BOOST_ASIO_CONCURRENCY_HINT_IS_LOCKING(SCHEDULER,
+          state->service_list_->io_context_.concurrency_hint()))
+    {
+      std::logic_error ex(
+          "Thread-unsafe io_context objects require "
+          "exclusive access to signal handling.");
+      boost::asio::detail::throw_exception(ex);
+    }
+  }
+
   // Insert service into linked list of all services.
   service->next_ = state->service_list_;
   service->prev_ = 0;
@@ -620,7 +640,7 @@ void signal_set_service::close_descriptors()
 void signal_set_service::start_wait_op(
     signal_set_service::implementation_type& impl, signal_op* op)
 {
-  io_service_.work_started();
+  io_context_.work_started();
 
   signal_state* state = get_signal_state();
   static_mutex::scoped_lock lock(state->mutex_);
@@ -632,7 +652,7 @@ void signal_set_service::start_wait_op(
     {
       --reg->undelivered_;
       op->signal_number_ = reg->signal_number_;
-      io_service_.post_deferred_completion(op);
+      io_context_.post_deferred_completion(op);
       return;
     }
 
diff --git a/include/boost/asio/detail/impl/socket_ops.ipp b/include/boost/asio/detail/impl/socket_ops.ipp
index c9683f4a09..2b97387a9f 100644
--- a/include/boost/asio/detail/impl/socket_ops.ipp
+++ b/include/boost/asio/detail/impl/socket_ops.ipp
@@ -169,7 +169,7 @@ socket_type sync_accept(socket_type s, state_type state,
       return invalid_socket;
 
     // Wait for socket to become ready.
-    if (socket_ops::poll_read(s, 0, ec) < 0)
+    if (socket_ops::poll_read(s, 0, -1, ec) < 0)
       return invalid_socket;
   }
 }
@@ -242,8 +242,6 @@ bool non_blocking_accept(socket_type s,
     if (ec == boost::asio::error::would_block
         || ec == boost::asio::error::try_again)
     {
-      if (state & user_set_non_blocking)
-        return true;
       // Fall through to retry operation.
     }
     else if (ec == boost::asio::error::connection_aborted)
@@ -506,7 +504,7 @@ void sync_connect(socket_type s, const socket_addr_type* addr,
   }
 
   // Wait for socket to become ready.
-  if (socket_ops::poll_connect(s, ec) < 0)
+  if (socket_ops::poll_connect(s, -1, ec) < 0)
     return;
 
   // Get the error code from the connect operation.
@@ -828,7 +826,7 @@ size_t sync_recv(socket_type s, state_type state, buf* bufs,
       return 0;
 
     // Wait for socket to become ready.
-    if (socket_ops::poll_read(s, 0, ec) < 0)
+    if (socket_ops::poll_read(s, 0, -1, ec) < 0)
       return 0;
   }
 }
@@ -967,7 +965,7 @@ size_t sync_recvfrom(socket_type s, state_type state, buf* bufs,
       return 0;
 
     // Wait for socket to become ready.
-    if (socket_ops::poll_read(s, 0, ec) < 0)
+    if (socket_ops::poll_read(s, 0, -1, ec) < 0)
       return 0;
   }
 }
@@ -1080,7 +1078,7 @@ size_t sync_recvmsg(socket_type s, state_type state,
       return 0;
 
     // Wait for socket to become ready.
-    if (socket_ops::poll_read(s, 0, ec) < 0)
+    if (socket_ops::poll_read(s, 0, -1, ec) < 0)
       return 0;
   }
 }
@@ -1207,7 +1205,7 @@ size_t sync_send(socket_type s, state_type state, const buf* bufs,
       return 0;
 
     // Wait for socket to become ready.
-    if (socket_ops::poll_write(s, 0, ec) < 0)
+    if (socket_ops::poll_write(s, 0, -1, ec) < 0)
       return 0;
   }
 }
@@ -1331,7 +1329,7 @@ size_t sync_sendto(socket_type s, state_type state, const buf* bufs,
       return 0;
 
     // Wait for socket to become ready.
-    if (socket_ops::poll_write(s, 0, ec) < 0)
+    if (socket_ops::poll_write(s, 0, -1, ec) < 0)
       return 0;
   }
 }
@@ -1785,7 +1783,8 @@ int select(int nfds, fd_set* readfds, fd_set* writefds,
 #endif
 }
 
-int poll_read(socket_type s, state_type state, boost::system::error_code& ec)
+int poll_read(socket_type s, state_type state,
+    int msec, boost::system::error_code& ec)
 {
   if (s == invalid_socket)
   {
@@ -1799,10 +1798,22 @@ int poll_read(socket_type s, state_type state, boost::system::error_code& ec)
   fd_set fds;
   FD_ZERO(&fds);
   FD_SET(s, &fds);
-  timeval zero_timeout;
-  zero_timeout.tv_sec = 0;
-  zero_timeout.tv_usec = 0;
-  timeval* timeout = (state & user_set_non_blocking) ? &zero_timeout : 0;
+  timeval timeout_obj;
+  timeval* timeout;
+  if (state & user_set_non_blocking)
+  {
+    timeout_obj.tv_sec = 0;
+    timeout_obj.tv_usec = 0;
+    timeout = &timeout_obj;
+  }
+  else if (msec >= 0)
+  {
+    timeout_obj.tv_sec = msec / 1000;
+    timeout_obj.tv_usec = (msec % 1000) * 1000;
+    timeout = &timeout_obj;
+  }
+  else
+    timeout = 0;
   clear_last_error();
   int result = error_wrapper(::select(s + 1, &fds, 0, 0, timeout), ec);
 #else // defined(BOOST_ASIO_WINDOWS)
@@ -1812,7 +1823,7 @@ int poll_read(socket_type s, state_type state, boost::system::error_code& ec)
   fds.fd = s;
   fds.events = POLLIN;
   fds.revents = 0;
-  int timeout = (state & user_set_non_blocking) ? 0 : -1;
+  int timeout = (state & user_set_non_blocking) ? 0 : msec;
   clear_last_error();
   int result = error_wrapper(::poll(&fds, 1, timeout), ec);
 #endif // defined(BOOST_ASIO_WINDOWS)
@@ -1826,7 +1837,8 @@ int poll_read(socket_type s, state_type state, boost::system::error_code& ec)
   return result;
 }
 
-int poll_write(socket_type s, state_type state, boost::system::error_code& ec)
+int poll_write(socket_type s, state_type state,
+    int msec, boost::system::error_code& ec)
 {
   if (s == invalid_socket)
   {
@@ -1840,10 +1852,22 @@ int poll_write(socket_type s, state_type state, boost::system::error_code& ec)
   fd_set fds;
   FD_ZERO(&fds);
   FD_SET(s, &fds);
-  timeval zero_timeout;
-  zero_timeout.tv_sec = 0;
-  zero_timeout.tv_usec = 0;
-  timeval* timeout = (state & user_set_non_blocking) ? &zero_timeout : 0;
+  timeval timeout_obj;
+  timeval* timeout;
+  if (state & user_set_non_blocking)
+  {
+    timeout_obj.tv_sec = 0;
+    timeout_obj.tv_usec = 0;
+    timeout = &timeout_obj;
+  }
+  else if (msec >= 0)
+  {
+    timeout_obj.tv_sec = msec / 1000;
+    timeout_obj.tv_usec = (msec % 1000) * 1000;
+    timeout = &timeout_obj;
+  }
+  else
+    timeout = 0;
   clear_last_error();
   int result = error_wrapper(::select(s + 1, 0, &fds, 0, timeout), ec);
 #else // defined(BOOST_ASIO_WINDOWS)
@@ -1853,7 +1877,7 @@ int poll_write(socket_type s, state_type state, boost::system::error_code& ec)
   fds.fd = s;
   fds.events = POLLOUT;
   fds.revents = 0;
-  int timeout = (state & user_set_non_blocking) ? 0 : -1;
+  int timeout = (state & user_set_non_blocking) ? 0 : msec;
   clear_last_error();
   int result = error_wrapper(::poll(&fds, 1, timeout), ec);
 #endif // defined(BOOST_ASIO_WINDOWS)
@@ -1867,7 +1891,61 @@ int poll_write(socket_type s, state_type state, boost::system::error_code& ec)
   return result;
 }
 
-int poll_connect(socket_type s, boost::system::error_code& ec)
+int poll_error(socket_type s, state_type state,
+    int msec, boost::system::error_code& ec)
+{
+  if (s == invalid_socket)
+  {
+    ec = boost::asio::error::bad_descriptor;
+    return socket_error_retval;
+  }
+
+#if defined(BOOST_ASIO_WINDOWS) \
+  || defined(__CYGWIN__) \
+  || defined(__SYMBIAN32__)
+  fd_set fds;
+  FD_ZERO(&fds);
+  FD_SET(s, &fds);
+  timeval timeout_obj;
+  timeval* timeout;
+  if (state & user_set_non_blocking)
+  {
+    timeout_obj.tv_sec = 0;
+    timeout_obj.tv_usec = 0;
+    timeout = &timeout_obj;
+  }
+  else if (msec >= 0)
+  {
+    timeout_obj.tv_sec = msec / 1000;
+    timeout_obj.tv_usec = (msec % 1000) * 1000;
+    timeout = &timeout_obj;
+  }
+  else
+    timeout = 0;
+  clear_last_error();
+  int result = error_wrapper(::select(s + 1, 0, 0, &fds, timeout), ec);
+#else // defined(BOOST_ASIO_WINDOWS)
+      // || defined(__CYGWIN__)
+      // || defined(__SYMBIAN32__)
+  pollfd fds;
+  fds.fd = s;
+  fds.events = POLLPRI | POLLERR | POLLHUP;
+  fds.revents = 0;
+  int timeout = (state & user_set_non_blocking) ? 0 : msec;
+  clear_last_error();
+  int result = error_wrapper(::poll(&fds, 1, timeout), ec);
+#endif // defined(BOOST_ASIO_WINDOWS)
+       // || defined(__CYGWIN__)
+       // || defined(__SYMBIAN32__)
+  if (result == 0)
+    ec = (state & user_set_non_blocking)
+      ? boost::asio::error::would_block : boost::system::error_code();
+  else if (result > 0)
+    ec = boost::system::error_code();
+  return result;
+}
+
+int poll_connect(socket_type s, int msec, boost::system::error_code& ec)
 {
   if (s == invalid_socket)
   {
@@ -1884,9 +1962,19 @@ int poll_connect(socket_type s, boost::system::error_code& ec)
   fd_set except_fds;
   FD_ZERO(&except_fds);
   FD_SET(s, &except_fds);
+  timeval timeout_obj;
+  timeval* timeout;
+  if (msec >= 0)
+  {
+    timeout_obj.tv_sec = msec / 1000;
+    timeout_obj.tv_usec = (msec % 1000) * 1000;
+    timeout = &timeout_obj;
+  }
+  else
+    timeout = 0;
   clear_last_error();
   int result = error_wrapper(::select(
-        s + 1, 0, &write_fds, &except_fds, 0), ec);
+        s + 1, 0, &write_fds, &except_fds, timeout), ec);
   if (result >= 0)
     ec = boost::system::error_code();
   return result;
@@ -1898,7 +1986,7 @@ int poll_connect(socket_type s, boost::system::error_code& ec)
   fds.events = POLLOUT;
   fds.revents = 0;
   clear_last_error();
-  int result = error_wrapper(::poll(&fds, 1, -1), ec);
+  int result = error_wrapper(::poll(&fds, 1, msec), ec);
   if (result >= 0)
     ec = boost::system::error_code();
   return result;
@@ -3346,7 +3434,6 @@ boost::system::error_code getnameinfo(const socket_addr_type* addr,
   using namespace std; // For memcpy.
   sockaddr_storage_type tmp_addr;
   memcpy(&tmp_addr, addr, addrlen);
-  tmp_addr.ss_len = addrlen;
   addr = reinterpret_cast<socket_addr_type*>(&tmp_addr);
   clear_last_error();
   return getnameinfo_emulation(addr, addrlen,
diff --git a/include/boost/asio/detail/impl/strand_executor_service.hpp b/include/boost/asio/detail/impl/strand_executor_service.hpp
new file mode 100644
index 0000000000..6821c2ec64
--- /dev/null
+++ b/include/boost/asio/detail/impl/strand_executor_service.hpp
@@ -0,0 +1,181 @@
+//
+// detail/impl/strand_executor_service.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_HPP
+#define BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/call_stack.hpp>
+#include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/recycling_allocator.hpp>
+#include <boost/asio/executor_work_guard.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Executor>
+class strand_executor_service::invoker
+{
+public:
+  invoker(const implementation_type& impl, Executor& ex)
+    : impl_(impl),
+      work_(ex)
+  {
+  }
+
+  invoker(const invoker& other)
+    : impl_(other.impl_),
+      work_(other.work_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  invoker(invoker&& other)
+    : impl_(BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_)),
+      work_(BOOST_ASIO_MOVE_CAST(executor_work_guard<Executor>)(other.work_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  struct on_invoker_exit
+  {
+    invoker* this_;
+
+    ~on_invoker_exit()
+    {
+      this_->impl_->mutex_->lock();
+      this_->impl_->ready_queue_.push(this_->impl_->waiting_queue_);
+      bool more_handlers = this_->impl_->locked_ =
+        !this_->impl_->ready_queue_.empty();
+      this_->impl_->mutex_->unlock();
+
+      if (more_handlers)
+      {
+        Executor ex(this_->work_.get_executor());
+        recycling_allocator<void> allocator;
+        ex.post(BOOST_ASIO_MOVE_CAST(invoker)(*this_), allocator);
+      }
+    }
+  };
+
+  void operator()()
+  {
+    // Indicate that this strand is executing on the current thread.
+    call_stack<strand_impl>::context ctx(impl_.get());
+
+    // Ensure the next handler, if any, is scheduled on block exit.
+    on_invoker_exit on_exit = { this };
+    (void)on_exit;
+
+    // Run all ready handlers. No lock is required since the ready queue is
+    // accessed only within the strand.
+    boost::system::error_code ec;
+    while (scheduler_operation* o = impl_->ready_queue_.front())
+    {
+      impl_->ready_queue_.pop();
+      o->complete(impl_.get(), ec, 0);
+    }
+  }
+
+private:
+  implementation_type impl_;
+  executor_work_guard<Executor> work_;
+};
+
+template <typename Executor, typename Function, typename Allocator>
+void strand_executor_service::dispatch(const implementation_type& impl,
+    Executor& ex, BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a)
+{
+  typedef typename decay<Function>::type function_type;
+
+  // If we are already in the strand then the function can run immediately.
+  if (call_stack<strand_impl>::contains(impl.get()))
+  {
+    // Make a local, non-const copy of the function.
+    function_type tmp(BOOST_ASIO_MOVE_CAST(Function)(function));
+
+    fenced_block b(fenced_block::full);
+    boost_asio_handler_invoke_helpers::invoke(tmp, tmp);
+    return;
+  }
+
+  // Allocate and construct an operation to wrap the function.
+  typedef executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(function), a);
+
+  BOOST_ASIO_HANDLER_CREATION((impl->service_->context(), *p.p,
+        "strand_executor", impl.get(), 0, "dispatch"));
+
+  // Add the function to the strand and schedule the strand if required.
+  bool first = enqueue(impl, p.p);
+  p.v = p.p = 0;
+  if (first)
+    ex.dispatch(invoker<Executor>(impl, ex), a);
+}
+
+// Request invocation of the given function and return immediately.
+template <typename Executor, typename Function, typename Allocator>
+void strand_executor_service::post(const implementation_type& impl,
+    Executor& ex, BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a)
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Allocate and construct an operation to wrap the function.
+  typedef executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(function), a);
+
+  BOOST_ASIO_HANDLER_CREATION((impl->service_->context(), *p.p,
+        "strand_executor", impl.get(), 0, "post"));
+
+  // Add the function to the strand and schedule the strand if required.
+  bool first = enqueue(impl, p.p);
+  p.v = p.p = 0;
+  if (first)
+    ex.post(invoker<Executor>(impl, ex), a);
+}
+
+// Request invocation of the given function and return immediately.
+template <typename Executor, typename Function, typename Allocator>
+void strand_executor_service::defer(const implementation_type& impl,
+    Executor& ex, BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a)
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Allocate and construct an operation to wrap the function.
+  typedef executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(function), a);
+
+  BOOST_ASIO_HANDLER_CREATION((impl->service_->context(), *p.p,
+        "strand_executor", impl.get(), 0, "defer"));
+
+  // Add the function to the strand and schedule the strand if required.
+  bool first = enqueue(impl, p.p);
+  p.v = p.p = 0;
+  if (first)
+    ex.defer(invoker<Executor>(impl, ex), a);
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_HPP
diff --git a/include/boost/asio/detail/impl/strand_executor_service.ipp b/include/boost/asio/detail/impl/strand_executor_service.ipp
new file mode 100644
index 0000000000..353304ae27
--- /dev/null
+++ b/include/boost/asio/detail/impl/strand_executor_service.ipp
@@ -0,0 +1,126 @@
+//
+// detail/impl/strand_executor_service.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_IPP
+#define BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/strand_executor_service.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+strand_executor_service::strand_executor_service(execution_context& ctx)
+  : execution_context_service_base<strand_executor_service>(ctx),
+    mutex_(),
+    salt_(0),
+    impl_list_(0)
+{
+}
+
+void strand_executor_service::shutdown()
+{
+  op_queue<scheduler_operation> ops;
+
+  boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+  strand_impl* impl = impl_list_;
+  while (impl)
+  {
+    ops.push(impl->waiting_queue_);
+    ops.push(impl->ready_queue_);
+    impl = impl->next_;
+  }
+}
+
+strand_executor_service::implementation_type
+strand_executor_service::create_implementation()
+{
+  implementation_type new_impl(new strand_impl);
+  new_impl->locked_ = false;
+
+  boost::asio::detail::mutex::scoped_lock lock(mutex_);
+
+  // Select a mutex from the pool of shared mutexes.
+  std::size_t salt = salt_++;
+  std::size_t mutex_index = reinterpret_cast<std::size_t>(new_impl.get());
+  mutex_index += (reinterpret_cast<std::size_t>(new_impl.get()) >> 3);
+  mutex_index ^= salt + 0x9e3779b9 + (mutex_index << 6) + (mutex_index >> 2);
+  mutex_index = mutex_index % num_mutexes;
+  if (!mutexes_[mutex_index].get())
+    mutexes_[mutex_index].reset(new mutex);
+  new_impl->mutex_ = mutexes_[mutex_index].get();
+
+  // Insert implementation into linked list of all implementations.
+  new_impl->next_ = impl_list_;
+  new_impl->prev_ = 0;
+  if (impl_list_)
+    impl_list_->prev_ = new_impl.get();
+  impl_list_ = new_impl.get();
+  new_impl->service_ = this;
+
+  return new_impl;
+}
+
+strand_executor_service::strand_impl::~strand_impl()
+{
+  boost::asio::detail::mutex::scoped_lock lock(service_->mutex_);
+
+  // Remove implementation from linked list of all implementations.
+  if (service_->impl_list_ == this)
+    service_->impl_list_ = next_;
+  if (prev_)
+    prev_->next_ = next_;
+  if (next_)
+    next_->prev_= prev_;
+}
+
+bool strand_executor_service::enqueue(const implementation_type& impl,
+    scheduler_operation* op)
+{
+  impl->mutex_->lock();
+  if (impl->locked_)
+  {
+    // Some other function already holds the strand lock. Enqueue for later.
+    impl->waiting_queue_.push(op);
+    impl->mutex_->unlock();
+    return false;
+  }
+  else
+  {
+    // The function is acquiring the strand lock and so is responsible for
+    // scheduling the strand.
+    impl->locked_ = true;
+    impl->mutex_->unlock();
+    impl->ready_queue_.push(op);
+    return true;
+  }
+}
+
+bool strand_executor_service::running_in_this_thread(
+    const implementation_type& impl)
+{
+  return !!call_stack<strand_impl>::contains(impl.get());
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_IMPL_STRAND_EXECUTOR_SERVICE_IPP
diff --git a/include/boost/asio/detail/impl/strand_service.hpp b/include/boost/asio/detail/impl/strand_service.hpp
index 4167f686d1..df21099971 100644
--- a/include/boost/asio/detail/impl/strand_service.hpp
+++ b/include/boost/asio/detail/impl/strand_service.hpp
@@ -15,12 +15,12 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/call_stack.hpp>
 #include <boost/asio/detail/completion_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -36,7 +36,7 @@ inline strand_service::strand_impl::strand_impl()
 
 struct strand_service::on_dispatch_exit
 {
-  io_service_impl* io_service_;
+  io_context_impl* io_context_;
   strand_impl* impl_;
 
   ~on_dispatch_exit()
@@ -47,7 +47,7 @@ struct strand_service::on_dispatch_exit
     impl_->mutex_.unlock();
 
     if (more_handlers)
-      io_service_->post_immediate_completion(impl_, false);
+      io_context_->post_immediate_completion(impl_, false);
   }
 };
 
@@ -66,11 +66,11 @@ void strand_service::dispatch(strand_service::implementation_type& impl,
   // Allocate and construct an operation to wrap the handler.
   typedef completion_handler<Handler> op;
   typename op::ptr p = { boost::asio::detail::addressof(handler),
-    boost_asio_handler_alloc_helpers::allocate(
-      sizeof(op), handler), 0 };
+    op::ptr::allocate(handler), 0 };
   p.p = new (p.v) op(handler);
 
-  BOOST_ASIO_HANDLER_CREATION((p.p, "strand", impl, "dispatch"));
+  BOOST_ASIO_HANDLER_CREATION((this->context(),
+        *p.p, "strand", impl, 0, "dispatch"));
 
   bool dispatch_immediately = do_dispatch(impl, p.p);
   operation* o = p.p;
@@ -82,15 +82,15 @@ void strand_service::dispatch(strand_service::implementation_type& impl,
     call_stack<strand_impl>::context ctx(impl);
 
     // Ensure the next handler, if any, is scheduled on block exit.
-    on_dispatch_exit on_exit = { &io_service_, impl };
+    on_dispatch_exit on_exit = { &io_context_, impl };
     (void)on_exit;
 
     completion_handler<Handler>::do_complete(
-        &io_service_, o, boost::system::error_code(), 0);
+        &io_context_, o, boost::system::error_code(), 0);
   }
 }
 
-// Request the io_service to invoke the given handler and return immediately.
+// Request the io_context to invoke the given handler and return immediately.
 template <typename Handler>
 void strand_service::post(strand_service::implementation_type& impl,
     Handler& handler)
@@ -101,11 +101,11 @@ void strand_service::post(strand_service::implementation_type& impl,
   // Allocate and construct an operation to wrap the handler.
   typedef completion_handler<Handler> op;
   typename op::ptr p = { boost::asio::detail::addressof(handler),
-    boost_asio_handler_alloc_helpers::allocate(
-      sizeof(op), handler), 0 };
+    op::ptr::allocate(handler), 0 };
   p.p = new (p.v) op(handler);
 
-  BOOST_ASIO_HANDLER_CREATION((p.p, "strand", impl, "post"));
+  BOOST_ASIO_HANDLER_CREATION((this->context(),
+        *p.p, "strand", impl, 0, "post"));
 
   do_post(impl, p.p, is_continuation);
   p.v = p.p = 0;
diff --git a/include/boost/asio/detail/impl/strand_service.ipp b/include/boost/asio/detail/impl/strand_service.ipp
index 54ecde2cc7..e92355d837 100644
--- a/include/boost/asio/detail/impl/strand_service.ipp
+++ b/include/boost/asio/detail/impl/strand_service.ipp
@@ -27,7 +27,7 @@ namespace detail {
 
 struct strand_service::on_do_complete_exit
 {
-  io_service_impl* owner_;
+  io_context_impl* owner_;
   strand_impl* impl_;
 
   ~on_do_complete_exit()
@@ -42,15 +42,15 @@ struct strand_service::on_do_complete_exit
   }
 };
 
-strand_service::strand_service(boost::asio::io_service& io_service)
-  : boost::asio::detail::service_base<strand_service>(io_service),
-    io_service_(boost::asio::use_service<io_service_impl>(io_service)),
+strand_service::strand_service(boost::asio::io_context& io_context)
+  : boost::asio::detail::service_base<strand_service>(io_context),
+    io_context_(boost::asio::use_service<io_context_impl>(io_context)),
     mutex_(),
     salt_(0)
 {
 }
 
-void strand_service::shutdown_service()
+void strand_service::shutdown()
 {
   op_queue<operation> ops;
 
@@ -93,9 +93,9 @@ bool strand_service::running_in_this_thread(
 
 bool strand_service::do_dispatch(implementation_type& impl, operation* op)
 {
-  // If we are running inside the io_service, and no other handler already
+  // If we are running inside the io_context, and no other handler already
   // holds the strand lock, then the handler can run immediately.
-  bool can_dispatch = io_service_.can_dispatch();
+  bool can_dispatch = io_context_.can_dispatch();
   impl->mutex_.lock();
   if (can_dispatch && !impl->locked_)
   {
@@ -118,7 +118,7 @@ bool strand_service::do_dispatch(implementation_type& impl, operation* op)
     impl->locked_ = true;
     impl->mutex_.unlock();
     impl->ready_queue_.push(op);
-    io_service_.post_immediate_completion(impl, false);
+    io_context_.post_immediate_completion(impl, false);
   }
 
   return false;
@@ -141,11 +141,11 @@ void strand_service::do_post(implementation_type& impl,
     impl->locked_ = true;
     impl->mutex_.unlock();
     impl->ready_queue_.push(op);
-    io_service_.post_immediate_completion(impl, is_continuation);
+    io_context_.post_immediate_completion(impl, is_continuation);
   }
 }
 
-void strand_service::do_complete(io_service_impl* owner, operation* base,
+void strand_service::do_complete(void* owner, operation* base,
     const boost::system::error_code& ec, std::size_t /*bytes_transferred*/)
 {
   if (owner)
@@ -156,15 +156,16 @@ void strand_service::do_complete(io_service_impl* owner, operation* base,
     call_stack<strand_impl>::context ctx(impl);
 
     // Ensure the next handler, if any, is scheduled on block exit.
-    on_do_complete_exit on_exit = { owner, impl };
-    (void)on_exit;
+    on_do_complete_exit on_exit;
+    on_exit.owner_ = static_cast<io_context_impl*>(owner);
+    on_exit.impl_ = impl;
 
     // Run all ready handlers. No lock is required since the ready queue is
     // accessed only within the strand.
     while (operation* o = impl->ready_queue_.front())
     {
       impl->ready_queue_.pop();
-      o->complete(*owner, ec, 0);
+      o->complete(owner, ec, 0);
     }
   }
 }
diff --git a/include/boost/asio/detail/impl/task_io_service.hpp b/include/boost/asio/detail/impl/task_io_service.hpp
deleted file mode 100644
index 09b4ba6985..0000000000
--- a/include/boost/asio/detail/impl/task_io_service.hpp
+++ /dev/null
@@ -1,80 +0,0 @@
-//
-// detail/impl/task_io_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_HPP
-#define BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/addressof.hpp>
-#include <boost/asio/detail/completion_handler.hpp>
-#include <boost/asio/detail/fenced_block.hpp>
-#include <boost/asio/detail/handler_alloc_helpers.hpp>
-#include <boost/asio/detail/handler_cont_helpers.hpp>
-#include <boost/asio/detail/handler_invoke_helpers.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace detail {
-
-template <typename Handler>
-void task_io_service::dispatch(Handler& handler)
-{
-  if (thread_call_stack::contains(this))
-  {
-    fenced_block b(fenced_block::full);
-    boost_asio_handler_invoke_helpers::invoke(handler, handler);
-  }
-  else
-  {
-    // Allocate and construct an operation to wrap the handler.
-    typedef completion_handler<Handler> op;
-    typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
-    p.p = new (p.v) op(handler);
-
-    BOOST_ASIO_HANDLER_CREATION((p.p, "io_service", this, "dispatch"));
-
-    do_dispatch(p.p);
-    p.v = p.p = 0;
-  }
-}
-
-template <typename Handler>
-void task_io_service::post(Handler& handler)
-{
-  bool is_continuation =
-    boost_asio_handler_cont_helpers::is_continuation(handler);
-
-  // Allocate and construct an operation to wrap the handler.
-  typedef completion_handler<Handler> op;
-  typename op::ptr p = { boost::asio::detail::addressof(handler),
-    boost_asio_handler_alloc_helpers::allocate(
-      sizeof(op), handler), 0 };
-  p.p = new (p.v) op(handler);
-
-  BOOST_ASIO_HANDLER_CREATION((p.p, "io_service", this, "post"));
-
-  post_immediate_completion(p.p, is_continuation);
-  p.v = p.p = 0;
-}
-
-} // namespace detail
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_DETAIL_IMPL_TASK_IO_SERVICE_HPP
diff --git a/include/boost/asio/detail/impl/timer_queue_ptime.ipp b/include/boost/asio/detail/impl/timer_queue_ptime.ipp
index 0216d20ba5..885ee7d06e 100644
--- a/include/boost/asio/detail/impl/timer_queue_ptime.ipp
+++ b/include/boost/asio/detail/impl/timer_queue_ptime.ipp
@@ -16,12 +16,13 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+
 #include <boost/asio/detail/timer_queue_ptime.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
-#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-
 namespace boost {
 namespace asio {
 namespace detail {
@@ -75,12 +76,18 @@ std::size_t timer_queue<time_traits<boost::posix_time::ptime> >::cancel_timer(
   return impl_.cancel_timer(timer, ops, max_cancelled);
 }
 
+void timer_queue<time_traits<boost::posix_time::ptime> >::move_timer(
+    per_timer_data& target, per_timer_data& source)
+{
+  impl_.move_timer(target, source);
+}
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
 
-#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+
 #endif // BOOST_ASIO_DETAIL_IMPL_TIMER_QUEUE_PTIME_IPP
diff --git a/include/boost/asio/detail/impl/win_iocp_handle_service.ipp b/include/boost/asio/detail/impl/win_iocp_handle_service.ipp
index ea513bc1dd..4f35a1c0a8 100644
--- a/include/boost/asio/detail/impl/win_iocp_handle_service.ipp
+++ b/include/boost/asio/detail/impl/win_iocp_handle_service.ipp
@@ -67,14 +67,15 @@ public:
 };
 
 win_iocp_handle_service::win_iocp_handle_service(
-    boost::asio::io_service& io_service)
-  : iocp_service_(boost::asio::use_service<win_iocp_io_service>(io_service)),
+    boost::asio::io_context& io_context)
+  : service_base<win_iocp_handle_service>(io_context),
+    iocp_service_(boost::asio::use_service<win_iocp_io_context>(io_context)),
     mutex_(),
     impl_list_(0)
 {
 }
 
-void win_iocp_handle_service::shutdown_service()
+void win_iocp_handle_service::shutdown()
 {
   // Close all implementations, causing all operations to complete.
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
@@ -200,7 +201,8 @@ boost::system::error_code win_iocp_handle_service::close(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("handle", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((iocp_service_.context(), "handle",
+          &impl, reinterpret_cast<uintmax_t>(impl.handle_), "close"));
 
     if (!::CloseHandle(impl.handle_))
     {
@@ -234,7 +236,8 @@ boost::system::error_code win_iocp_handle_service::cancel(
     return ec;
   }
 
-  BOOST_ASIO_HANDLER_OPERATION(("handle", &impl, "cancel"));
+  BOOST_ASIO_HANDLER_OPERATION((iocp_service_.context(), "handle",
+        &impl, reinterpret_cast<uintmax_t>(impl.handle_), "cancel"));
 
   if (FARPROC cancel_io_ex_ptr = ::GetProcAddress(
         ::GetModuleHandleA("KERNEL32"), "CancelIoEx"))
@@ -304,7 +307,7 @@ size_t win_iocp_handle_service::do_write(
   }
 
   // A request to write 0 bytes on a handle is a no-op.
-  if (boost::asio::buffer_size(buffer) == 0)
+  if (buffer.size() == 0)
   {
     ec = boost::system::error_code();
     return 0;
@@ -319,9 +322,8 @@ size_t win_iocp_handle_service::do_write(
   // Write the data. 
   overlapped.Offset = offset & 0xFFFFFFFF;
   overlapped.OffsetHigh = (offset >> 32) & 0xFFFFFFFF;
-  BOOL ok = ::WriteFile(impl.handle_,
-      boost::asio::buffer_cast<LPCVOID>(buffer),
-      static_cast<DWORD>(boost::asio::buffer_size(buffer)), 0, &overlapped);
+  BOOL ok = ::WriteFile(impl.handle_, buffer.data(),
+      static_cast<DWORD>(buffer.size()), 0, &overlapped);
   if (!ok) 
   {
     DWORD last_error = ::GetLastError();
@@ -360,7 +362,7 @@ void win_iocp_handle_service::start_write_op(
   {
     iocp_service_.on_completion(op, boost::asio::error::bad_descriptor);
   }
-  else if (boost::asio::buffer_size(buffer) == 0)
+  else if (buffer.size() == 0)
   {
     // A request to write 0 bytes on a handle is a no-op.
     iocp_service_.on_completion(op);
@@ -370,9 +372,8 @@ void win_iocp_handle_service::start_write_op(
     DWORD bytes_transferred = 0;
     op->Offset = offset & 0xFFFFFFFF;
     op->OffsetHigh = (offset >> 32) & 0xFFFFFFFF;
-    BOOL ok = ::WriteFile(impl.handle_,
-        boost::asio::buffer_cast<LPCVOID>(buffer),
-        static_cast<DWORD>(boost::asio::buffer_size(buffer)),
+    BOOL ok = ::WriteFile(impl.handle_, buffer.data(),
+        static_cast<DWORD>(buffer.size()),
         &bytes_transferred, op);
     DWORD last_error = ::GetLastError();
     if (!ok && last_error != ERROR_IO_PENDING
@@ -398,7 +399,7 @@ size_t win_iocp_handle_service::do_read(
   }
   
   // A request to read 0 bytes on a stream handle is a no-op.
-  if (boost::asio::buffer_size(buffer) == 0)
+  if (buffer.size() == 0)
   {
     ec = boost::system::error_code();
     return 0;
@@ -413,9 +414,8 @@ size_t win_iocp_handle_service::do_read(
   // Read some data.
   overlapped.Offset = offset & 0xFFFFFFFF;
   overlapped.OffsetHigh = (offset >> 32) & 0xFFFFFFFF;
-  BOOL ok = ::ReadFile(impl.handle_,
-      boost::asio::buffer_cast<LPVOID>(buffer),
-      static_cast<DWORD>(boost::asio::buffer_size(buffer)), 0, &overlapped);
+  BOOL ok = ::ReadFile(impl.handle_, buffer.data(),
+      static_cast<DWORD>(buffer.size()), 0, &overlapped);
   if (!ok) 
   {
     DWORD last_error = ::GetLastError();
@@ -468,7 +468,7 @@ void win_iocp_handle_service::start_read_op(
   {
     iocp_service_.on_completion(op, boost::asio::error::bad_descriptor);
   }
-  else if (boost::asio::buffer_size(buffer) == 0)
+  else if (buffer.size() == 0)
   {
     // A request to read 0 bytes on a handle is a no-op.
     iocp_service_.on_completion(op);
@@ -478,9 +478,8 @@ void win_iocp_handle_service::start_read_op(
     DWORD bytes_transferred = 0;
     op->Offset = offset & 0xFFFFFFFF;
     op->OffsetHigh = (offset >> 32) & 0xFFFFFFFF;
-    BOOL ok = ::ReadFile(impl.handle_,
-        boost::asio::buffer_cast<LPVOID>(buffer),
-        static_cast<DWORD>(boost::asio::buffer_size(buffer)),
+    BOOL ok = ::ReadFile(impl.handle_, buffer.data(),
+        static_cast<DWORD>(buffer.size()),
         &bytes_transferred, op);
     DWORD last_error = ::GetLastError();
     if (!ok && last_error != ERROR_IO_PENDING
@@ -508,7 +507,8 @@ void win_iocp_handle_service::close_for_destruction(implementation_type& impl)
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("handle", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((iocp_service_.context(), "handle",
+          &impl, reinterpret_cast<uintmax_t>(impl.handle_), "close"));
 
     ::CloseHandle(impl.handle_);
     impl.handle_ = INVALID_HANDLE_VALUE;
diff --git a/include/boost/asio/detail/impl/win_iocp_io_service.hpp b/include/boost/asio/detail/impl/win_iocp_io_context.hpp
similarity index 56%
rename from include/boost/asio/detail/impl/win_iocp_io_service.hpp
rename to include/boost/asio/detail/impl/win_iocp_io_context.hpp
index e3505cb852..948b0c93d4 100644
--- a/include/boost/asio/detail/impl/win_iocp_io_service.hpp
+++ b/include/boost/asio/detail/impl/win_iocp_io_context.hpp
@@ -1,5 +1,5 @@
 //
-// detail/impl/win_iocp_io_service.hpp
+// detail/impl/win_iocp_io_context.hpp
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_SERVICE_HPP
-#define BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_SERVICE_HPP
+#ifndef BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_CONTEXT_HPP
+#define BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_CONTEXT_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -19,11 +19,11 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/completion_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -31,62 +31,22 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-template <typename Handler>
-void win_iocp_io_service::dispatch(Handler& handler)
-{
-  if (thread_call_stack::contains(this))
-  {
-    fenced_block b(fenced_block::full);
-    boost_asio_handler_invoke_helpers::invoke(handler, handler);
-  }
-  else
-  {
-    // Allocate and construct an operation to wrap the handler.
-    typedef completion_handler<Handler> op;
-    typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
-    p.p = new (p.v) op(handler);
-
-    BOOST_ASIO_HANDLER_CREATION((p.p, "io_service", this, "dispatch"));
-
-    post_immediate_completion(p.p, false);
-    p.v = p.p = 0;
-  }
-}
-
-template <typename Handler>
-void win_iocp_io_service::post(Handler& handler)
-{
-  // Allocate and construct an operation to wrap the handler.
-  typedef completion_handler<Handler> op;
-  typename op::ptr p = { boost::asio::detail::addressof(handler),
-    boost_asio_handler_alloc_helpers::allocate(
-      sizeof(op), handler), 0 };
-  p.p = new (p.v) op(handler);
-
-  BOOST_ASIO_HANDLER_CREATION((p.p, "io_service", this, "post"));
-
-  post_immediate_completion(p.p, false);
-  p.v = p.p = 0;
-}
-
 template <typename Time_Traits>
-void win_iocp_io_service::add_timer_queue(
+void win_iocp_io_context::add_timer_queue(
     timer_queue<Time_Traits>& queue)
 {
   do_add_timer_queue(queue);
 }
 
 template <typename Time_Traits>
-void win_iocp_io_service::remove_timer_queue(
+void win_iocp_io_context::remove_timer_queue(
     timer_queue<Time_Traits>& queue)
 {
   do_remove_timer_queue(queue);
 }
 
 template <typename Time_Traits>
-void win_iocp_io_service::schedule_timer(timer_queue<Time_Traits>& queue,
+void win_iocp_io_context::schedule_timer(timer_queue<Time_Traits>& queue,
     const typename Time_Traits::time_type& time,
     typename timer_queue<Time_Traits>::per_timer_data& timer, wait_op* op)
 {
@@ -106,7 +66,7 @@ void win_iocp_io_service::schedule_timer(timer_queue<Time_Traits>& queue,
 }
 
 template <typename Time_Traits>
-std::size_t win_iocp_io_service::cancel_timer(timer_queue<Time_Traits>& queue,
+std::size_t win_iocp_io_context::cancel_timer(timer_queue<Time_Traits>& queue,
     typename timer_queue<Time_Traits>::per_timer_data& timer,
     std::size_t max_cancelled)
 {
@@ -121,6 +81,19 @@ std::size_t win_iocp_io_service::cancel_timer(timer_queue<Time_Traits>& queue,
   return n;
 }
 
+template <typename Time_Traits>
+void win_iocp_io_context::move_timer(timer_queue<Time_Traits>& queue,
+    typename timer_queue<Time_Traits>::per_timer_data& to,
+    typename timer_queue<Time_Traits>::per_timer_data& from)
+{
+  boost::asio::detail::mutex::scoped_lock lock(dispatch_mutex_);
+  op_queue<operation> ops;
+  queue.cancel_timer(to, ops);
+  queue.move_timer(to, from);
+  lock.unlock();
+  post_deferred_completions(ops);
+}
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
@@ -129,4 +102,4 @@ std::size_t win_iocp_io_service::cancel_timer(timer_queue<Time_Traits>& queue,
 
 #endif // defined(BOOST_ASIO_HAS_IOCP)
 
-#endif // BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_SERVICE_HPP
+#endif // BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_CONTEXT_HPP
diff --git a/include/boost/asio/detail/impl/win_iocp_io_service.ipp b/include/boost/asio/detail/impl/win_iocp_io_context.ipp
similarity index 81%
rename from include/boost/asio/detail/impl/win_iocp_io_service.ipp
rename to include/boost/asio/detail/impl/win_iocp_io_context.ipp
index a5bfcbbdea..9071836aa9 100644
--- a/include/boost/asio/detail/impl/win_iocp_io_service.ipp
+++ b/include/boost/asio/detail/impl/win_iocp_io_context.ipp
@@ -1,5 +1,5 @@
 //
-// detail/impl/win_iocp_io_service.ipp
+// detail/impl/win_iocp_io_context.ipp
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_SERVICE_IPP
-#define BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_SERVICE_IPP
+#ifndef BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_CONTEXT_IPP
+#define BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_CONTEXT_IPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -20,13 +20,12 @@
 #if defined(BOOST_ASIO_HAS_IOCP)
 
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
 #include <boost/asio/detail/cstdint.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
 #include <boost/asio/detail/limits.hpp>
 #include <boost/asio/detail/throw_error.hpp>
-#include <boost/asio/detail/win_iocp_io_service.hpp>
+#include <boost/asio/detail/win_iocp_io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -34,51 +33,51 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-struct win_iocp_io_service::work_finished_on_block_exit
+struct win_iocp_io_context::work_finished_on_block_exit
 {
   ~work_finished_on_block_exit()
   {
-    io_service_->work_finished();
+    io_context_->work_finished();
   }
 
-  win_iocp_io_service* io_service_;
+  win_iocp_io_context* io_context_;
 };
 
-struct win_iocp_io_service::timer_thread_function
+struct win_iocp_io_context::timer_thread_function
 {
   void operator()()
   {
-    while (::InterlockedExchangeAdd(&io_service_->shutdown_, 0) == 0)
+    while (::InterlockedExchangeAdd(&io_context_->shutdown_, 0) == 0)
     {
-      if (::WaitForSingleObject(io_service_->waitable_timer_.handle,
+      if (::WaitForSingleObject(io_context_->waitable_timer_.handle,
             INFINITE) == WAIT_OBJECT_0)
       {
-        ::InterlockedExchange(&io_service_->dispatch_required_, 1);
-        ::PostQueuedCompletionStatus(io_service_->iocp_.handle,
+        ::InterlockedExchange(&io_context_->dispatch_required_, 1);
+        ::PostQueuedCompletionStatus(io_context_->iocp_.handle,
             0, wake_for_dispatch, 0);
       }
     }
   }
 
-  win_iocp_io_service* io_service_;
+  win_iocp_io_context* io_context_;
 };
 
-win_iocp_io_service::win_iocp_io_service(
-    boost::asio::io_service& io_service, size_t concurrency_hint)
-  : boost::asio::detail::service_base<win_iocp_io_service>(io_service),
+win_iocp_io_context::win_iocp_io_context(
+    boost::asio::execution_context& ctx, int concurrency_hint)
+  : execution_context_service_base<win_iocp_io_context>(ctx),
     iocp_(),
     outstanding_work_(0),
     stopped_(0),
     stop_event_posted_(0),
     shutdown_(0),
     gqcs_timeout_(get_gqcs_timeout()),
-    dispatch_required_(0)
+    dispatch_required_(0),
+    concurrency_hint_(concurrency_hint)
 {
   BOOST_ASIO_HANDLER_TRACKING_INIT;
 
   iocp_.handle = ::CreateIoCompletionPort(INVALID_HANDLE_VALUE, 0, 0,
-      static_cast<DWORD>(concurrency_hint < DWORD(~0)
-        ? concurrency_hint : DWORD(~0)));
+      static_cast<DWORD>(concurrency_hint >= 0 ? concurrency_hint : DWORD(~0)));
   if (!iocp_.handle)
   {
     DWORD last_error = ::GetLastError();
@@ -88,7 +87,7 @@ win_iocp_io_service::win_iocp_io_service(
   }
 }
 
-void win_iocp_io_service::shutdown_service()
+void win_iocp_io_context::shutdown()
 {
   ::InterlockedExchange(&shutdown_, 1);
 
@@ -132,7 +131,7 @@ void win_iocp_io_service::shutdown_service()
     timer_thread_->join();
 }
 
-boost::system::error_code win_iocp_io_service::register_handle(
+boost::system::error_code win_iocp_io_context::register_handle(
     HANDLE handle, boost::system::error_code& ec)
 {
   if (::CreateIoCompletionPort(handle, iocp_.handle, 0, 0) == 0)
@@ -148,7 +147,7 @@ boost::system::error_code win_iocp_io_service::register_handle(
   return ec;
 }
 
-size_t win_iocp_io_service::run(boost::system::error_code& ec)
+size_t win_iocp_io_context::run(boost::system::error_code& ec)
 {
   if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
   {
@@ -161,13 +160,13 @@ size_t win_iocp_io_service::run(boost::system::error_code& ec)
   thread_call_stack::context ctx(this, this_thread);
 
   size_t n = 0;
-  while (do_one(true, ec))
+  while (do_one(INFINITE, ec))
     if (n != (std::numeric_limits<size_t>::max)())
       ++n;
   return n;
 }
 
-size_t win_iocp_io_service::run_one(boost::system::error_code& ec)
+size_t win_iocp_io_context::run_one(boost::system::error_code& ec)
 {
   if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
   {
@@ -179,10 +178,25 @@ size_t win_iocp_io_service::run_one(boost::system::error_code& ec)
   win_iocp_thread_info this_thread;
   thread_call_stack::context ctx(this, this_thread);
 
-  return do_one(true, ec);
+  return do_one(INFINITE, ec);
 }
 
-size_t win_iocp_io_service::poll(boost::system::error_code& ec)
+size_t win_iocp_io_context::wait_one(long usec, boost::system::error_code& ec)
+{
+  if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
+  {
+    stop();
+    ec = boost::system::error_code();
+    return 0;
+  }
+
+  win_iocp_thread_info this_thread;
+  thread_call_stack::context ctx(this, this_thread);
+
+  return do_one(usec < 0 ? INFINITE : ((usec - 1) / 1000 + 1), ec);
+}
+
+size_t win_iocp_io_context::poll(boost::system::error_code& ec)
 {
   if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
   {
@@ -195,13 +209,13 @@ size_t win_iocp_io_service::poll(boost::system::error_code& ec)
   thread_call_stack::context ctx(this, this_thread);
 
   size_t n = 0;
-  while (do_one(false, ec))
+  while (do_one(0, ec))
     if (n != (std::numeric_limits<size_t>::max)())
       ++n;
   return n;
 }
 
-size_t win_iocp_io_service::poll_one(boost::system::error_code& ec)
+size_t win_iocp_io_context::poll_one(boost::system::error_code& ec)
 {
   if (::InterlockedExchangeAdd(&outstanding_work_, 0) == 0)
   {
@@ -213,10 +227,10 @@ size_t win_iocp_io_service::poll_one(boost::system::error_code& ec)
   win_iocp_thread_info this_thread;
   thread_call_stack::context ctx(this, this_thread);
 
-  return do_one(false, ec);
+  return do_one(0, ec);
 }
 
-void win_iocp_io_service::stop()
+void win_iocp_io_context::stop()
 {
   if (::InterlockedExchange(&stopped_, 1) == 0)
   {
@@ -233,7 +247,7 @@ void win_iocp_io_service::stop()
   }
 }
 
-void win_iocp_io_service::post_deferred_completion(win_iocp_operation* op)
+void win_iocp_io_context::post_deferred_completion(win_iocp_operation* op)
 {
   // Flag the operation as ready.
   op->ready_ = 1;
@@ -248,7 +262,7 @@ void win_iocp_io_service::post_deferred_completion(win_iocp_operation* op)
   }
 }
 
-void win_iocp_io_service::post_deferred_completions(
+void win_iocp_io_context::post_deferred_completions(
     op_queue<win_iocp_operation>& ops)
 {
   while (win_iocp_operation* op = ops.front())
@@ -270,7 +284,7 @@ void win_iocp_io_service::post_deferred_completions(
   }
 }
 
-void win_iocp_io_service::abandon_operations(
+void win_iocp_io_context::abandon_operations(
     op_queue<win_iocp_operation>& ops)
 {
   while (win_iocp_operation* op = ops.front())
@@ -281,7 +295,7 @@ void win_iocp_io_service::abandon_operations(
   }
 }
 
-void win_iocp_io_service::on_pending(win_iocp_operation* op)
+void win_iocp_io_context::on_pending(win_iocp_operation* op)
 {
   if (::InterlockedCompareExchange(&op->ready_, 1, 0) == 1)
   {
@@ -297,7 +311,7 @@ void win_iocp_io_service::on_pending(win_iocp_operation* op)
   }
 }
 
-void win_iocp_io_service::on_completion(win_iocp_operation* op,
+void win_iocp_io_context::on_completion(win_iocp_operation* op,
     DWORD last_error, DWORD bytes_transferred)
 {
   // Flag that the operation is ready for invocation.
@@ -320,7 +334,7 @@ void win_iocp_io_service::on_completion(win_iocp_operation* op,
   }
 }
 
-void win_iocp_io_service::on_completion(win_iocp_operation* op,
+void win_iocp_io_context::on_completion(win_iocp_operation* op,
     const boost::system::error_code& ec, DWORD bytes_transferred)
 {
   // Flag that the operation is ready for invocation.
@@ -342,7 +356,7 @@ void win_iocp_io_service::on_completion(win_iocp_operation* op,
   }
 }
 
-size_t win_iocp_io_service::do_one(bool block, boost::system::error_code& ec)
+size_t win_iocp_io_context::do_one(DWORD msec, boost::system::error_code& ec)
 {
   for (;;)
   {
@@ -364,8 +378,9 @@ size_t win_iocp_io_service::do_one(bool block, boost::system::error_code& ec)
     dword_ptr_t completion_key = 0;
     LPOVERLAPPED overlapped = 0;
     ::SetLastError(0);
-    BOOL ok = ::GetQueuedCompletionStatus(iocp_.handle, &bytes_transferred,
-        &completion_key, &overlapped, block ? gqcs_timeout_ : 0);
+    BOOL ok = ::GetQueuedCompletionStatus(iocp_.handle,
+        &bytes_transferred, &completion_key, &overlapped,
+        msec < gqcs_timeout_ ? msec : gqcs_timeout_);
     DWORD last_error = ::GetLastError();
 
     if (overlapped)
@@ -402,7 +417,7 @@ size_t win_iocp_io_service::do_one(bool block, boost::system::error_code& ec)
         work_finished_on_block_exit on_exit = { this };
         (void)on_exit;
 
-        op->complete(*this, result_ec, bytes_transferred);
+        op->complete(this, result_ec, bytes_transferred);
         ec = boost::system::error_code();
         return 1;
       }
@@ -416,8 +431,9 @@ size_t win_iocp_io_service::do_one(bool block, boost::system::error_code& ec)
         return 0;
       }
 
-      // If we're not polling we need to keep going until we get a real handler.
-      if (block)
+      // If we're waiting indefinitely we need to keep going until we get a
+      // real handler.
+      if (msec == INFINITE)
         continue;
 
       ec = boost::system::error_code();
@@ -456,7 +472,7 @@ size_t win_iocp_io_service::do_one(bool block, boost::system::error_code& ec)
   }
 }
 
-DWORD win_iocp_io_service::get_gqcs_timeout()
+DWORD win_iocp_io_context::get_gqcs_timeout()
 {
   OSVERSIONINFOEX osvi;
   ZeroMemory(&osvi, sizeof(osvi));
@@ -472,7 +488,7 @@ DWORD win_iocp_io_service::get_gqcs_timeout()
   return default_gqcs_timeout;
 }
 
-void win_iocp_io_service::do_add_timer_queue(timer_queue_base& queue)
+void win_iocp_io_context::do_add_timer_queue(timer_queue_base& queue)
 {
   mutex::scoped_lock lock(dispatch_mutex_);
 
@@ -503,14 +519,14 @@ void win_iocp_io_service::do_add_timer_queue(timer_queue_base& queue)
   }
 }
 
-void win_iocp_io_service::do_remove_timer_queue(timer_queue_base& queue)
+void win_iocp_io_context::do_remove_timer_queue(timer_queue_base& queue)
 {
   mutex::scoped_lock lock(dispatch_mutex_);
 
   timer_queues_.erase(&queue);
 }
 
-void win_iocp_io_service::update_timeout()
+void win_iocp_io_context::update_timeout()
 {
   if (timer_thread_.get())
   {
@@ -537,4 +553,4 @@ void win_iocp_io_service::update_timeout()
 
 #endif // defined(BOOST_ASIO_HAS_IOCP)
 
-#endif // BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_SERVICE_IPP
+#endif // BOOST_ASIO_DETAIL_IMPL_WIN_IOCP_IO_CONTEXT_IPP
diff --git a/include/boost/asio/detail/impl/win_iocp_serial_port_service.ipp b/include/boost/asio/detail/impl/win_iocp_serial_port_service.ipp
index 32ba34684b..c0d2dbbd59 100644
--- a/include/boost/asio/detail/impl/win_iocp_serial_port_service.ipp
+++ b/include/boost/asio/detail/impl/win_iocp_serial_port_service.ipp
@@ -30,12 +30,13 @@ namespace asio {
 namespace detail {
 
 win_iocp_serial_port_service::win_iocp_serial_port_service(
-    boost::asio::io_service& io_service)
-  : handle_service_(io_service)
+    boost::asio::io_context& io_context)
+  : service_base<win_iocp_serial_port_service>(io_context),
+    handle_service_(io_context)
 {
 }
 
-void win_iocp_serial_port_service::shutdown_service()
+void win_iocp_serial_port_service::shutdown()
 {
 }
 
diff --git a/include/boost/asio/detail/impl/win_iocp_socket_service_base.ipp b/include/boost/asio/detail/impl/win_iocp_socket_service_base.ipp
index 93f5ed0713..e9a5049345 100644
--- a/include/boost/asio/detail/impl/win_iocp_socket_service_base.ipp
+++ b/include/boost/asio/detail/impl/win_iocp_socket_service_base.ipp
@@ -28,24 +28,24 @@ namespace asio {
 namespace detail {
 
 win_iocp_socket_service_base::win_iocp_socket_service_base(
-    boost::asio::io_service& io_service)
-  : io_service_(io_service),
-    iocp_service_(use_service<win_iocp_io_service>(io_service)),
+    boost::asio::io_context& io_context)
+  : io_context_(io_context),
+    iocp_service_(use_service<win_iocp_io_context>(io_context)),
     reactor_(0),
     connect_ex_(0),
+    nt_set_info_(0),
     mutex_(),
     impl_list_(0)
 {
 }
 
-void win_iocp_socket_service_base::shutdown_service()
+void win_iocp_socket_service_base::base_shutdown()
 {
   // Close all implementations, causing all operations to complete.
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
   base_implementation_type* impl = impl_list_;
   while (impl)
   {
-    boost::system::error_code ignored_ec;
     close_for_destruction(*impl);
     impl = impl->next_;
   }
@@ -167,12 +167,13 @@ boost::system::error_code win_iocp_socket_service_base::close(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("socket", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((iocp_service_.context(),
+          "socket", &impl, impl.socket_, "close"));
 
     // Check if the reactor was created, in which case we need to close the
     // socket on the reactor as well to cancel any operations that might be
     // running there.
-    reactor* r = static_cast<reactor*>(
+    select_reactor* r = static_cast<select_reactor*>(
           interlocked_compare_exchange_pointer(
             reinterpret_cast<void**>(&reactor_), 0, 0));
     if (r)
@@ -198,6 +199,39 @@ boost::system::error_code win_iocp_socket_service_base::close(
   return ec;
 }
 
+socket_type win_iocp_socket_service_base::release(
+    win_iocp_socket_service_base::base_implementation_type& impl,
+    boost::system::error_code& ec)
+{
+  if (!is_open(impl))
+    return invalid_socket;
+
+  cancel(impl, ec);
+  if (ec)
+    return invalid_socket;
+
+  nt_set_info_fn fn = get_nt_set_info();
+  if (fn == 0)
+  {
+    ec = boost::asio::error::operation_not_supported;
+    return invalid_socket;
+  }
+
+  HANDLE sock_as_handle = reinterpret_cast<HANDLE>(impl.socket_);
+  ULONG_PTR iosb[2] = { 0, 0 };
+  void* info[2] = { 0, 0 };
+  if (fn(sock_as_handle, iosb, &info, sizeof(info),
+        61 /* FileReplaceCompletionInformation */))
+  {
+    ec = boost::asio::error::operation_not_supported;
+    return invalid_socket;
+  }
+
+  socket_type tmp = impl.socket_;
+  impl.socket_ = invalid_socket;
+  return tmp;
+}
+
 boost::system::error_code win_iocp_socket_service_base::cancel(
     win_iocp_socket_service_base::base_implementation_type& impl,
     boost::system::error_code& ec)
@@ -208,7 +242,8 @@ boost::system::error_code win_iocp_socket_service_base::cancel(
     return ec;
   }
 
-  BOOST_ASIO_HANDLER_OPERATION(("socket", &impl, "cancel"));
+  BOOST_ASIO_HANDLER_OPERATION((iocp_service_.context(),
+        "socket", &impl, impl.socket_, "cancel"));
 
   if (FARPROC cancel_io_ex_ptr = ::GetProcAddress(
         ::GetModuleHandleA("KERNEL32"), "CancelIoEx"))
@@ -279,7 +314,7 @@ boost::system::error_code win_iocp_socket_service_base::cancel(
   // Cancel any operations started via the reactor.
   if (!ec)
   {
-    reactor* r = static_cast<reactor*>(
+    select_reactor* r = static_cast<select_reactor*>(
           interlocked_compare_exchange_pointer(
             reinterpret_cast<void**>(&reactor_), 0, 0));
     if (r)
@@ -445,7 +480,7 @@ void win_iocp_socket_service_base::start_null_buffers_receive_op(
   {
     start_reactor_op(impl,
         (flags & socket_base::message_out_of_band)
-          ? reactor::except_op : reactor::read_op,
+          ? select_reactor::except_op : select_reactor::read_op,
         op);
   }
 }
@@ -537,7 +572,7 @@ void win_iocp_socket_service_base::start_reactor_op(
     win_iocp_socket_service_base::base_implementation_type& impl,
     int op_type, reactor_op* op)
 {
-  reactor& r = get_reactor();
+  select_reactor& r = get_reactor();
   update_cancellation_thread_id(impl);
 
   if (is_open(impl))
@@ -598,7 +633,7 @@ void win_iocp_socket_service_base::start_connect_op(
   }
 
   // Otherwise, fall back to a reactor-based implementation.
-  reactor& r = get_reactor();
+  select_reactor& r = get_reactor();
   update_cancellation_thread_id(impl);
 
   if ((impl.state_ & socket_ops::non_blocking) != 0
@@ -611,7 +646,7 @@ void win_iocp_socket_service_base::start_connect_op(
           || op->ec_ == boost::asio::error::would_block)
       {
         op->ec_ = boost::system::error_code();
-        r.start_op(reactor::connect_op, impl.socket_,
+        r.start_op(select_reactor::connect_op, impl.socket_,
             impl.reactor_data_, op, false, false);
         return;
       }
@@ -626,12 +661,13 @@ void win_iocp_socket_service_base::close_for_destruction(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("socket", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((iocp_service_.context(),
+          "socket", &impl, impl.socket_, "close"));
 
     // Check if the reactor was created, in which case we need to close the
     // socket on the reactor as well to cancel any operations that might be
     // running there.
-    reactor* r = static_cast<reactor*>(
+    select_reactor* r = static_cast<select_reactor*>(
           interlocked_compare_exchange_pointer(
             reinterpret_cast<void**>(&reactor_), 0, 0));
     if (r)
@@ -665,14 +701,14 @@ void win_iocp_socket_service_base::update_cancellation_thread_id(
 #endif // defined(BOOST_ASIO_ENABLE_CANCELIO)
 }
 
-reactor& win_iocp_socket_service_base::get_reactor()
+select_reactor& win_iocp_socket_service_base::get_reactor()
 {
-  reactor* r = static_cast<reactor*>(
+  select_reactor* r = static_cast<select_reactor*>(
         interlocked_compare_exchange_pointer(
           reinterpret_cast<void**>(&reactor_), 0, 0));
   if (!r)
   {
-    r = &(use_service<reactor>(io_service_));
+    r = &(use_service<select_reactor>(io_context_));
     interlocked_exchange_pointer(reinterpret_cast<void**>(&reactor_), r);
   }
   return *r;
@@ -713,6 +749,24 @@ win_iocp_socket_service_base::get_connect_ex(
 #endif // defined(BOOST_ASIO_DISABLE_CONNECTEX)
 }
 
+win_iocp_socket_service_base::nt_set_info_fn
+win_iocp_socket_service_base::get_nt_set_info()
+{
+  void* ptr = interlocked_compare_exchange_pointer(&nt_set_info_, 0, 0);
+  if (!ptr)
+  {
+    if (HMODULE h = ::GetModuleHandleA("NTDLL.DLL"))
+      ptr = reinterpret_cast<void*>(GetProcAddress(h, "NtSetInformationFile"));
+
+    // On failure, set nt_set_info_ to a special value to indicate that the
+    // NtSetInformationFile function is unavailable. That way we won't bother
+    // trying to look it up again.
+    interlocked_exchange_pointer(&nt_set_info_, ptr ? ptr : this);
+  }
+
+  return reinterpret_cast<nt_set_info_fn>(ptr == this ? 0 : ptr);
+}
+
 void* win_iocp_socket_service_base::interlocked_compare_exchange_pointer(
     void** dest, void* exch, void* cmp)
 {
diff --git a/include/boost/asio/detail/impl/win_object_handle_service.ipp b/include/boost/asio/detail/impl/win_object_handle_service.ipp
index a940161cba..31718a012b 100644
--- a/include/boost/asio/detail/impl/win_object_handle_service.ipp
+++ b/include/boost/asio/detail/impl/win_object_handle_service.ipp
@@ -29,15 +29,16 @@ namespace asio {
 namespace detail {
 
 win_object_handle_service::win_object_handle_service(
-    boost::asio::io_service& io_service)
-  : io_service_(boost::asio::use_service<io_service_impl>(io_service)),
+    boost::asio::io_context& io_context)
+  : service_base<win_object_handle_service>(io_context),
+    io_context_(boost::asio::use_service<io_context_impl>(io_context)),
     mutex_(),
     impl_list_(0),
     shutdown_(false)
 {
 }
 
-void win_object_handle_service::shutdown_service()
+void win_object_handle_service::shutdown()
 {
   mutex::scoped_lock lock(mutex_);
 
@@ -52,7 +53,7 @@ void win_object_handle_service::shutdown_service()
 
   lock.unlock();
 
-  io_service_.abandon_operations(ops);
+  io_context_.abandon_operations(ops);
 }
 
 void win_object_handle_service::construct(
@@ -178,7 +179,8 @@ void win_object_handle_service::destroy(
 
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("object_handle", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((io_context_.context(), "object_handle",
+          &impl, reinterpret_cast<uintmax_t>(impl.wait_handle_), "close"));
 
     HANDLE wait_handle = impl.wait_handle_;
     impl.wait_handle_ = INVALID_HANDLE_VALUE;
@@ -202,7 +204,7 @@ void win_object_handle_service::destroy(
     ::CloseHandle(impl.handle_);
     impl.handle_ = INVALID_HANDLE_VALUE;
 
-    io_service_.post_deferred_completions(ops);
+    io_context_.post_deferred_completions(ops);
   }
 }
 
@@ -227,7 +229,8 @@ boost::system::error_code win_object_handle_service::close(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("object_handle", &impl, "close"));
+    BOOST_ASIO_HANDLER_OPERATION((io_context_.context(), "object_handle",
+          &impl, reinterpret_cast<uintmax_t>(impl.wait_handle_), "close"));
 
     mutex::scoped_lock lock(mutex_);
 
@@ -262,7 +265,7 @@ boost::system::error_code win_object_handle_service::close(
           boost::asio::error::get_system_category());
     }
 
-    io_service_.post_deferred_completions(completed_ops);
+    io_context_.post_deferred_completions(completed_ops);
   }
   else
   {
@@ -278,7 +281,8 @@ boost::system::error_code win_object_handle_service::cancel(
 {
   if (is_open(impl))
   {
-    BOOST_ASIO_HANDLER_OPERATION(("object_handle", &impl, "cancel"));
+    BOOST_ASIO_HANDLER_OPERATION((io_context_.context(), "object_handle",
+          &impl, reinterpret_cast<uintmax_t>(impl.wait_handle_), "cancel"));
 
     mutex::scoped_lock lock(mutex_);
 
@@ -303,7 +307,7 @@ boost::system::error_code win_object_handle_service::cancel(
 
     ec = boost::system::error_code();
 
-    io_service_.post_deferred_completions(completed_ops);
+    io_context_.post_deferred_completions(completed_ops);
   }
   else
   {
@@ -337,7 +341,7 @@ void win_object_handle_service::wait(
 void win_object_handle_service::start_wait_op(
     win_object_handle_service::implementation_type& impl, wait_op* op)
 {
-  io_service_.work_started();
+  io_context_.work_started();
 
   if (is_open(impl))
   {
@@ -355,13 +359,13 @@ void win_object_handle_service::start_wait_op(
     else
     {
       lock.unlock();
-      io_service_.post_deferred_completion(op);
+      io_context_.post_deferred_completion(op);
     }
   }
   else
   {
     op->ec_ = boost::asio::error::bad_descriptor;
-    io_service_.post_deferred_completion(op);
+    io_context_.post_deferred_completion(op);
   }
 }
 
@@ -388,7 +392,7 @@ void win_object_handle_service::register_wait_callback(
     }
 
     lock.unlock();
-    io_service_.post_deferred_completions(completed_ops);
+    io_context_.post_deferred_completions(completed_ops);
   }
 }
 
@@ -430,9 +434,9 @@ void win_object_handle_service::wait_callback(PVOID param, BOOLEAN)
       }
     }
 
-    io_service_impl& ios = impl->owner_->io_service_;
+    io_context_impl& ioc = impl->owner_->io_context_;
     lock.unlock();
-    ios.post_deferred_completions(completed_ops);
+    ioc.post_deferred_completions(completed_ops);
   }
 }
 
diff --git a/include/boost/asio/detail/impl/win_thread.ipp b/include/boost/asio/detail/impl/win_thread.ipp
index e2d9384007..c90c3f3986 100644
--- a/include/boost/asio/detail/impl/win_thread.ipp
+++ b/include/boost/asio/detail/impl/win_thread.ipp
@@ -56,6 +56,13 @@ void win_thread::join()
   }
 }
 
+std::size_t win_thread::hardware_concurrency()
+{
+  SYSTEM_INFO system_info;
+  ::GetSystemInfo(&system_info);
+  return system_info.dwNumberOfProcessors;
+}
+
 void win_thread::start_thread(func_base* arg, unsigned int stack_size)
 {
   ::HANDLE entry_event = 0;
diff --git a/include/boost/asio/detail/impl/winrt_ssocket_service_base.ipp b/include/boost/asio/detail/impl/winrt_ssocket_service_base.ipp
index f5990a97ad..a7a340b70b 100644
--- a/include/boost/asio/detail/impl/winrt_ssocket_service_base.ipp
+++ b/include/boost/asio/detail/impl/winrt_ssocket_service_base.ipp
@@ -31,15 +31,15 @@ namespace asio {
 namespace detail {
 
 winrt_ssocket_service_base::winrt_ssocket_service_base(
-    boost::asio::io_service& io_service)
-  : io_service_(use_service<io_service_impl>(io_service)),
-    async_manager_(use_service<winrt_async_manager>(io_service)),
+    boost::asio::io_context& io_context)
+  : io_context_(use_service<io_context_impl>(io_context)),
+    async_manager_(use_service<winrt_async_manager>(io_context)),
     mutex_(),
     impl_list_(0)
 {
 }
 
-void winrt_ssocket_service_base::shutdown_service()
+void winrt_ssocket_service_base::base_shutdown()
 {
   // Close all implementations, causing all operations to complete.
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
@@ -149,6 +149,23 @@ boost::system::error_code winrt_ssocket_service_base::close(
   return ec;
 }
 
+winrt_ssocket_service_base::native_handle_type
+winrt_ssocket_service_base::release(
+    winrt_ssocket_service_base::base_implementation_type& impl,
+    boost::system::error_code& ec)
+{
+  if (!is_open(impl))
+    return nullptr;
+
+  cancel(impl, ec);
+  if (ec)
+    return nullptr;
+
+  native_handle_type tmp = impl.socket_;
+  impl.socket_ = nullptr;
+  return tmp;
+}
+
 std::size_t winrt_ssocket_service_base::do_get_endpoint(
     const base_implementation_type& impl, bool local,
     void* addr, std::size_t addr_len, boost::system::error_code& ec) const
@@ -382,7 +399,7 @@ void winrt_ssocket_service_base::start_connect_op(
   if (!is_open(impl))
   {
     op->ec_ = boost::asio::error::bad_descriptor;
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
     return;
   }
 
@@ -411,7 +428,7 @@ void winrt_ssocket_service_base::start_connect_op(
 
   if (op->ec_)
   {
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
     return;
   }
 
@@ -426,7 +443,7 @@ void winrt_ssocket_service_base::start_connect_op(
   {
     op->ec_ = boost::system::error_code(
         e->HResult, boost::system::system_category());
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
   }
 }
 
@@ -450,7 +467,7 @@ std::size_t winrt_ssocket_service_base::do_send(
   try
   {
     buffer_sequence_adapter<boost::asio::const_buffer,
-      boost::asio::const_buffers_1> bufs(boost::asio::buffer(data));
+      boost::asio::const_buffer> bufs(boost::asio::buffer(data));
 
     if (bufs.all_empty())
     {
@@ -477,25 +494,25 @@ void winrt_ssocket_service_base::start_send_op(
   if (flags)
   {
     op->ec_ = boost::asio::error::operation_not_supported;
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
     return;
   }
 
   if (!is_open(impl))
   {
     op->ec_ = boost::asio::error::bad_descriptor;
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
     return;
   }
 
   try
   {
     buffer_sequence_adapter<boost::asio::const_buffer,
-        boost::asio::const_buffers_1> bufs(boost::asio::buffer(data));
+        boost::asio::const_buffer> bufs(boost::asio::buffer(data));
 
     if (bufs.all_empty())
     {
-      io_service_.post_immediate_completion(op, is_continuation);
+      io_context_.post_immediate_completion(op, is_continuation);
       return;
     }
 
@@ -506,7 +523,7 @@ void winrt_ssocket_service_base::start_send_op(
   {
     op->ec_ = boost::system::error_code(e->HResult,
         boost::system::system_category());
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
   }
 }
 
@@ -530,7 +547,7 @@ std::size_t winrt_ssocket_service_base::do_receive(
   try
   {
     buffer_sequence_adapter<boost::asio::mutable_buffer,
-        boost::asio::mutable_buffers_1> bufs(boost::asio::buffer(data));
+        boost::asio::mutable_buffer> bufs(boost::asio::buffer(data));
 
     if (bufs.all_empty())
     {
@@ -568,25 +585,25 @@ void winrt_ssocket_service_base::start_receive_op(
   if (flags)
   {
     op->ec_ = boost::asio::error::operation_not_supported;
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
     return;
   }
 
   if (!is_open(impl))
   {
     op->ec_ = boost::asio::error::bad_descriptor;
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
     return;
   }
 
   try
   {
     buffer_sequence_adapter<boost::asio::mutable_buffer,
-        boost::asio::mutable_buffers_1> bufs(boost::asio::buffer(data));
+        boost::asio::mutable_buffer> bufs(boost::asio::buffer(data));
 
     if (bufs.all_empty())
     {
-      io_service_.post_immediate_completion(op, is_continuation);
+      io_context_.post_immediate_completion(op, is_continuation);
       return;
     }
 
@@ -599,7 +616,7 @@ void winrt_ssocket_service_base::start_receive_op(
   {
     op->ec_ = boost::system::error_code(e->HResult,
         boost::system::system_category());
-    io_service_.post_immediate_completion(op, is_continuation);
+    io_context_.post_immediate_completion(op, is_continuation);
   }
 }
 
diff --git a/include/boost/asio/detail/impl/winrt_timer_scheduler.hpp b/include/boost/asio/detail/impl/winrt_timer_scheduler.hpp
index 8d93e57962..b1522b4673 100644
--- a/include/boost/asio/detail/impl/winrt_timer_scheduler.hpp
+++ b/include/boost/asio/detail/impl/winrt_timer_scheduler.hpp
@@ -47,12 +47,12 @@ void winrt_timer_scheduler::schedule_timer(timer_queue<Time_Traits>& queue,
 
   if (shutdown_)
   {
-    io_service_.post_immediate_completion(op, false);
+    io_context_.post_immediate_completion(op, false);
     return;
   }
 
   bool earliest = queue.enqueue_timer(time, timer, op);
-  io_service_.work_started();
+  io_context_.work_started();
   if (earliest)
     event_.signal(lock);
 }
@@ -66,10 +66,23 @@ std::size_t winrt_timer_scheduler::cancel_timer(timer_queue<Time_Traits>& queue,
   op_queue<operation> ops;
   std::size_t n = queue.cancel_timer(timer, ops, max_cancelled);
   lock.unlock();
-  io_service_.post_deferred_completions(ops);
+  io_context_.post_deferred_completions(ops);
   return n;
 }
 
+template <typename Time_Traits>
+void winrt_timer_scheduler::move_timer(timer_queue<Time_Traits>& queue,
+    typename timer_queue<Time_Traits>::per_timer_data& to,
+    typename timer_queue<Time_Traits>::per_timer_data& from)
+{
+  boost::asio::detail::mutex::scoped_lock lock(mutex_);
+  op_queue<operation> ops;
+  queue.cancel_timer(to, ops);
+  queue.move_timer(to, from);
+  lock.unlock();
+  scheduler_.post_deferred_completions(ops);
+}
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/detail/impl/winrt_timer_scheduler.ipp b/include/boost/asio/detail/impl/winrt_timer_scheduler.ipp
index 914849d822..2e8145b6b8 100644
--- a/include/boost/asio/detail/impl/winrt_timer_scheduler.ipp
+++ b/include/boost/asio/detail/impl/winrt_timer_scheduler.ipp
@@ -29,9 +29,9 @@ namespace asio {
 namespace detail {
 
 winrt_timer_scheduler::winrt_timer_scheduler(
-    boost::asio::io_service& io_service)
-  : boost::asio::detail::service_base<winrt_timer_scheduler>(io_service),
-    io_service_(use_service<io_service_impl>(io_service)),
+    boost::asio::io_context& io_context)
+  : boost::asio::detail::service_base<winrt_timer_scheduler>(io_context),
+    io_context_(use_service<io_context_impl>(io_context)),
     mutex_(),
     event_(),
     timer_queues_(),
@@ -45,10 +45,10 @@ winrt_timer_scheduler::winrt_timer_scheduler(
 
 winrt_timer_scheduler::~winrt_timer_scheduler()
 {
-  shutdown_service();
+  shutdown();
 }
 
-void winrt_timer_scheduler::shutdown_service()
+void winrt_timer_scheduler::shutdown()
 {
   boost::asio::detail::mutex::scoped_lock lock(mutex_);
   shutdown_ = true;
@@ -65,10 +65,10 @@ void winrt_timer_scheduler::shutdown_service()
 
   op_queue<operation> ops;
   timer_queues_.get_all_timers(ops);
-  io_service_.abandon_operations(ops);
+  io_context_.abandon_operations(ops);
 }
 
-void winrt_timer_scheduler::fork_service(boost::asio::io_service::fork_event)
+void winrt_timer_scheduler::notify_fork(boost::asio::io_context::fork_event)
 {
 }
 
@@ -90,7 +90,7 @@ void winrt_timer_scheduler::run_thread()
     if (!ops.empty())
     {
       lock.unlock();
-      io_service_.post_deferred_completions(ops);
+      io_context_.post_deferred_completions(ops);
       lock.lock();
     }
   }
diff --git a/include/boost/asio/detail/io_control.hpp b/include/boost/asio/detail/io_control.hpp
index 6c7527d1cf..d235fa1fda 100644
--- a/include/boost/asio/detail/io_control.hpp
+++ b/include/boost/asio/detail/io_control.hpp
@@ -26,56 +26,6 @@ namespace asio {
 namespace detail {
 namespace io_control {
 
-// IO control command for non-blocking I/O.
-class non_blocking_io
-{
-public:
-  // Default constructor.
-  non_blocking_io()
-    : value_(0)
-  {
-  }
-
-  // Construct with a specific command value.
-  non_blocking_io(bool value)
-    : value_(value ? 1 : 0)
-  {
-  }
-
-  // Get the name of the IO control command.
-  int name() const
-  {
-    return static_cast<int>(BOOST_ASIO_OS_DEF(FIONBIO));
-  }
-
-  // Set the value of the I/O control command.
-  void set(bool value)
-  {
-    value_ = value ? 1 : 0;
-  }
-
-  // Get the current value of the I/O control command.
-  bool get() const
-  {
-    return value_ != 0;
-  }
-
-  // Get the address of the command data.
-  detail::ioctl_arg_type* data()
-  {
-    return &value_;
-  }
-
-  // Get the address of the command data.
-  const detail::ioctl_arg_type* data() const
-  {
-    return &value_;
-  }
-
-private:
-  detail::ioctl_arg_type value_;
-};
-
 // I/O control command for getting number of bytes available.
 class bytes_readable
 {
diff --git a/include/boost/asio/detail/is_buffer_sequence.hpp b/include/boost/asio/detail/is_buffer_sequence.hpp
new file mode 100644
index 0000000000..c788c55d28
--- /dev/null
+++ b/include/boost/asio/detail/is_buffer_sequence.hpp
@@ -0,0 +1,241 @@
+//
+// detail/is_buffer_sequence.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_IS_BUFFER_SEQUENCE_HPP
+#define BOOST_ASIO_DETAIL_IS_BUFFER_SEQUENCE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+class mutable_buffer;
+class const_buffer;
+
+namespace detail {
+
+struct buffer_sequence_memfns_base
+{
+  void begin();
+  void end();
+  void size();
+  void max_size();
+  void capacity();
+  void data();
+  void prepare();
+  void commit();
+  void consume();
+};
+
+template <typename T>
+struct buffer_sequence_memfns_derived
+  : T, buffer_sequence_memfns_base
+{
+};
+
+template <typename T, T>
+struct buffer_sequence_memfns_check
+{
+};
+
+template <typename>
+char (&begin_memfn_helper(...))[2];
+
+template <typename T>
+char begin_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::begin>*);
+
+template <typename>
+char (&end_memfn_helper(...))[2];
+
+template <typename T>
+char end_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::end>*);
+
+template <typename>
+char (&size_memfn_helper(...))[2];
+
+template <typename T>
+char size_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::size>*);
+
+template <typename>
+char (&max_size_memfn_helper(...))[2];
+
+template <typename T>
+char max_size_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::max_size>*);
+
+template <typename>
+char (&capacity_memfn_helper(...))[2];
+
+template <typename T>
+char capacity_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::capacity>*);
+
+template <typename>
+char (&data_memfn_helper(...))[2];
+
+template <typename T>
+char data_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::data>*);
+
+template <typename>
+char (&prepare_memfn_helper(...))[2];
+
+template <typename T>
+char prepare_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::data>*);
+
+template <typename>
+char (&commit_memfn_helper(...))[2];
+
+template <typename T>
+char commit_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::commit>*);
+
+template <typename>
+char (&consume_memfn_helper(...))[2];
+
+template <typename T>
+char consume_memfn_helper(
+    buffer_sequence_memfns_check<
+      void (buffer_sequence_memfns_base::*)(),
+      &buffer_sequence_memfns_derived<T>::consume>*);
+
+template <typename, typename>
+char (&buffer_element_type_helper(...))[2];
+
+#if defined(BOOST_ASIO_HAS_DECL_TYPE)
+
+template <typename T, typename Buffer>
+char buffer_element_type_helper(T* t,
+    typename enable_if<is_convertible<
+      decltype(*buffer_sequence_begin(*t)),
+        Buffer>::value>::type*);
+
+#else // defined(BOOST_ASIO_HAS_DECL_TYPE)
+
+template <typename T, typename Buffer>
+char buffer_element_type_helper(
+    typename T::const_iterator*,
+    typename enable_if<is_convertible<
+      typename T::value_type, Buffer>::value>::type*);
+
+#endif // defined(BOOST_ASIO_HAS_DECL_TYPE)
+
+template <typename>
+char (&const_buffers_type_typedef_helper(...))[2];
+
+template <typename T>
+char const_buffers_type_typedef_helper(
+    typename T::const_buffers_type*);
+
+template <typename>
+char (&mutable_buffers_type_typedef_helper(...))[2];
+
+template <typename T>
+char mutable_buffers_type_typedef_helper(
+    typename T::mutable_buffers_type*);
+
+template <typename T, typename Buffer>
+struct is_buffer_sequence_class
+  : integral_constant<bool,
+      sizeof(begin_memfn_helper<T>(0)) != 1 &&
+      sizeof(end_memfn_helper<T>(0)) != 1 &&
+      sizeof(buffer_element_type_helper<T, Buffer>(0, 0)) == 1>
+{
+};
+
+template <typename T, typename Buffer>
+struct is_buffer_sequence
+  : conditional<is_class<T>::value,
+      is_buffer_sequence_class<T, Buffer>,
+      false_type>::type
+{
+};
+
+template <>
+struct is_buffer_sequence<mutable_buffer, mutable_buffer>
+  : true_type
+{
+};
+
+template <>
+struct is_buffer_sequence<mutable_buffer, const_buffer>
+  : true_type
+{
+};
+
+template <>
+struct is_buffer_sequence<const_buffer, const_buffer>
+  : true_type
+{
+};
+
+template <>
+struct is_buffer_sequence<const_buffer, mutable_buffer>
+  : false_type
+{
+};
+
+template <typename T>
+struct is_dynamic_buffer_class
+  : integral_constant<bool,
+      sizeof(size_memfn_helper<T>(0)) != 1 &&
+      sizeof(max_size_memfn_helper<T>(0)) != 1 &&
+      sizeof(capacity_memfn_helper<T>(0)) != 1 &&
+      sizeof(data_memfn_helper<T>(0)) != 1 &&
+      sizeof(consume_memfn_helper<T>(0)) != 1 &&
+      sizeof(prepare_memfn_helper<T>(0)) != 1 &&
+      sizeof(commit_memfn_helper<T>(0)) != 1 &&
+      sizeof(const_buffers_type_typedef_helper<T>(0)) == 1 &&
+      sizeof(mutable_buffers_type_typedef_helper<T>(0)) == 1>
+{
+};
+
+template <typename T>
+struct is_dynamic_buffer
+  : conditional<is_class<T>::value,
+      is_dynamic_buffer_class<T>,
+      false_type>::type
+{
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_IS_BUFFER_SEQUENCE_HPP
diff --git a/include/boost/asio/detail/is_executor.hpp b/include/boost/asio/detail/is_executor.hpp
new file mode 100644
index 0000000000..43db5d0120
--- /dev/null
+++ b/include/boost/asio/detail/is_executor.hpp
@@ -0,0 +1,128 @@
+//
+// detail/is_executor.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_IS_EXECUTOR_HPP
+#define BOOST_ASIO_DETAIL_IS_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+struct executor_memfns_base
+{
+  void context();
+  void on_work_started();
+  void on_work_finished();
+  void dispatch();
+  void post();
+  void defer();
+};
+
+template <typename T>
+struct executor_memfns_derived
+  : T, executor_memfns_base
+{
+};
+
+template <typename T, T>
+struct executor_memfns_check
+{
+};
+
+template <typename>
+char (&context_memfn_helper(...))[2];
+
+template <typename T>
+char context_memfn_helper(
+    executor_memfns_check<
+      void (executor_memfns_base::*)(),
+      &executor_memfns_derived<T>::context>*);
+
+template <typename>
+char (&on_work_started_memfn_helper(...))[2];
+
+template <typename T>
+char on_work_started_memfn_helper(
+    executor_memfns_check<
+      void (executor_memfns_base::*)(),
+      &executor_memfns_derived<T>::on_work_started>*);
+
+template <typename>
+char (&on_work_finished_memfn_helper(...))[2];
+
+template <typename T>
+char on_work_finished_memfn_helper(
+    executor_memfns_check<
+      void (executor_memfns_base::*)(),
+      &executor_memfns_derived<T>::on_work_finished>*);
+
+template <typename>
+char (&dispatch_memfn_helper(...))[2];
+
+template <typename T>
+char dispatch_memfn_helper(
+    executor_memfns_check<
+      void (executor_memfns_base::*)(),
+      &executor_memfns_derived<T>::dispatch>*);
+
+template <typename>
+char (&post_memfn_helper(...))[2];
+
+template <typename T>
+char post_memfn_helper(
+    executor_memfns_check<
+      void (executor_memfns_base::*)(),
+      &executor_memfns_derived<T>::post>*);
+
+template <typename>
+char (&defer_memfn_helper(...))[2];
+
+template <typename T>
+char defer_memfn_helper(
+    executor_memfns_check<
+      void (executor_memfns_base::*)(),
+      &executor_memfns_derived<T>::defer>*);
+
+template <typename T>
+struct is_executor_class
+  : integral_constant<bool,
+      sizeof(context_memfn_helper<T>(0)) != 1 &&
+      sizeof(on_work_started_memfn_helper<T>(0)) != 1 &&
+      sizeof(on_work_finished_memfn_helper<T>(0)) != 1 &&
+      sizeof(dispatch_memfn_helper<T>(0)) != 1 &&
+      sizeof(post_memfn_helper<T>(0)) != 1 &&
+      sizeof(defer_memfn_helper<T>(0)) != 1>
+{
+};
+
+template <typename T>
+struct is_executor
+  : conditional<is_class<T>::value,
+      is_executor_class<T>,
+      false_type>::type
+{
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_IS_EXECUTOR_HPP
diff --git a/include/boost/asio/detail/kqueue_reactor.hpp b/include/boost/asio/detail/kqueue_reactor.hpp
index c6182b4d55..492b7ff016 100644
--- a/include/boost/asio/detail/kqueue_reactor.hpp
+++ b/include/boost/asio/detail/kqueue_reactor.hpp
@@ -35,7 +35,7 @@
 #include <boost/asio/detail/timer_queue_set.hpp>
 #include <boost/asio/detail/wait_op.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/execution_context.hpp>
 
 // Older versions of Mac OS X may not define EV_OOBAND.
 #if !defined(EV_OOBAND)
@@ -48,9 +48,15 @@ namespace boost {
 namespace asio {
 namespace detail {
 
+class scheduler;
+
 class kqueue_reactor
-  : public boost::asio::detail::service_base<kqueue_reactor>
+  : public execution_context_service_base<kqueue_reactor>
 {
+private:
+  // The mutex type used by this reactor.
+  typedef conditionally_enabled_mutex mutex;
+
 public:
   enum op_types { read_op = 0, write_op = 1,
     connect_op = 1, except_op = 2, max_ops = 3 };
@@ -58,6 +64,8 @@ class kqueue_reactor
   // Per-descriptor queues.
   struct descriptor_state
   {
+    descriptor_state(bool locking) : mutex_(locking) {}
+
     friend class kqueue_reactor;
     friend class object_pool_access;
 
@@ -75,17 +83,17 @@ class kqueue_reactor
   typedef descriptor_state* per_descriptor_data;
 
   // Constructor.
-  BOOST_ASIO_DECL kqueue_reactor(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL kqueue_reactor(boost::asio::execution_context& ctx);
 
   // Destructor.
   BOOST_ASIO_DECL ~kqueue_reactor();
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Recreate internal descriptors following a fork.
-  BOOST_ASIO_DECL void fork_service(
-      boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void notify_fork(
+      boost::asio::execution_context::fork_event fork_ev);
 
   // Initialise the task.
   BOOST_ASIO_DECL void init_task();
@@ -109,7 +117,7 @@ class kqueue_reactor
   // Post a reactor operation for immediate completion.
   void post_immediate_completion(reactor_op* op, bool is_continuation)
   {
-    io_service_.post_immediate_completion(op, is_continuation);
+    scheduler_.post_immediate_completion(op, is_continuation);
   }
 
   // Start a new operation. The reactor operation will be performed when the
@@ -163,8 +171,14 @@ class kqueue_reactor
       typename timer_queue<Time_Traits>::per_timer_data& timer,
       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
 
+  // Move the timer operations associated with the given timer.
+  template <typename Time_Traits>
+  void move_timer(timer_queue<Time_Traits>& queue,
+      typename timer_queue<Time_Traits>::per_timer_data& target,
+      typename timer_queue<Time_Traits>::per_timer_data& source);
+
   // Run the kqueue loop.
-  BOOST_ASIO_DECL void run(bool block, op_queue<operation>& ops);
+  BOOST_ASIO_DECL void run(long usec, op_queue<operation>& ops);
 
   // Interrupt the kqueue loop.
   BOOST_ASIO_DECL void interrupt();
@@ -187,10 +201,10 @@ class kqueue_reactor
   BOOST_ASIO_DECL void do_remove_timer_queue(timer_queue_base& queue);
 
   // Get the timeout value for the kevent call.
-  BOOST_ASIO_DECL timespec* get_timeout(timespec& ts);
+  BOOST_ASIO_DECL timespec* get_timeout(long usec, timespec& ts);
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_;
+  // The scheduler used to post completions.
+  scheduler& scheduler_;
 
   // Mutex to protect access to internal data.
   mutex mutex_;
diff --git a/include/boost/asio/detail/macos_fenced_block.hpp b/include/boost/asio/detail/macos_fenced_block.hpp
index 5ab7f91c5e..20a995ebec 100644
--- a/include/boost/asio/detail/macos_fenced_block.hpp
+++ b/include/boost/asio/detail/macos_fenced_block.hpp
@@ -20,6 +20,7 @@
 #if defined(__MACH__) && defined(__APPLE__)
 
 #include <libkern/OSAtomic.h>
+#include <boost/asio/detail/noncopyable.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
diff --git a/include/boost/asio/detail/memory.hpp b/include/boost/asio/detail/memory.hpp
index 479b57a3d1..c0a205e169 100644
--- a/include/boost/asio/detail/memory.hpp
+++ b/include/boost/asio/detail/memory.hpp
@@ -18,14 +18,55 @@
 #include <boost/asio/detail/config.hpp>
 #include <memory>
 
+#if !defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
+# include <boost/shared_ptr.hpp>
+# include <boost/weak_ptr.hpp>
+#endif // !defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
+
+#if !defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
+# include <boost/utility/addressof.hpp>
+#endif // !defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+#if defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
+using std::shared_ptr;
+using std::weak_ptr;
+#else // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
+using boost::shared_ptr;
+using boost::weak_ptr;
+#endif // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
+
+#if defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
+using std::addressof;
+#else // defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
+using boost::addressof;
+#endif // defined(BOOST_ASIO_HAS_STD_ADDRESSOF)
+
+} // namespace detail
+
 #if defined(BOOST_ASIO_HAS_CXX11_ALLOCATORS)
+using std::allocator_arg_t;
+# define BOOST_ASIO_USES_ALLOCATOR(t) \
+  namespace std { \
+    template <typename Allocator> \
+    struct uses_allocator<t, Allocator> : true_type {}; \
+  } \
+  /**/
 # define BOOST_ASIO_REBIND_ALLOC(alloc, t) \
   typename std::allocator_traits<alloc>::template rebind_alloc<t>
   /**/
 #else // defined(BOOST_ASIO_HAS_CXX11_ALLOCATORS)
+struct allocator_arg_t {};
+# define BOOST_ASIO_USES_ALLOCATOR(t)
 # define BOOST_ASIO_REBIND_ALLOC(alloc, t) \
   typename alloc::template rebind<t>::other
   /**/
 #endif // defined(BOOST_ASIO_HAS_CXX11_ALLOCATORS)
 
+} // namespace asio
+} // namespace boost
+
 #endif // BOOST_ASIO_DETAIL_MEMORY_HPP
diff --git a/include/boost/asio/detail/null_event.hpp b/include/boost/asio/detail/null_event.hpp
index 28ba5ede55..3bc74afb68 100644
--- a/include/boost/asio/detail/null_event.hpp
+++ b/include/boost/asio/detail/null_event.hpp
@@ -16,9 +16,6 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-
-#if !defined(BOOST_ASIO_HAS_THREADS)
-
 #include <boost/asio/detail/noncopyable.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -76,7 +73,20 @@ class null_event
   template <typename Lock>
   void wait(Lock&)
   {
+    do_wait();
   }
+
+  // Timed wait for the event to become signalled.
+  template <typename Lock>
+  bool wait_for_usec(Lock&, long usec)
+  {
+    do_wait_for_usec(usec);
+    return true;
+  }
+
+private:
+  BOOST_ASIO_DECL static void do_wait();
+  BOOST_ASIO_DECL static void do_wait_for_usec(long usec);
 };
 
 } // namespace detail
@@ -85,6 +95,8 @@ class null_event
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#endif // !defined(BOOST_ASIO_HAS_THREADS)
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/detail/impl/null_event.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
 
 #endif // BOOST_ASIO_DETAIL_NULL_EVENT_HPP
diff --git a/include/boost/asio/detail/null_fenced_block.hpp b/include/boost/asio/detail/null_fenced_block.hpp
index 27029b9e31..6d2b22f8cf 100644
--- a/include/boost/asio/detail/null_fenced_block.hpp
+++ b/include/boost/asio/detail/null_fenced_block.hpp
@@ -15,6 +15,8 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <boost/asio/detail/noncopyable.hpp>
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
diff --git a/include/boost/asio/detail/null_global.hpp b/include/boost/asio/detail/null_global.hpp
new file mode 100644
index 0000000000..fa24b5cbaf
--- /dev/null
+++ b/include/boost/asio/detail/null_global.hpp
@@ -0,0 +1,61 @@
+//
+// detail/null_global.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_NULL_GLOBAL_HPP
+#define BOOST_ASIO_DETAIL_NULL_GLOBAL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T>
+struct null_global_impl
+{
+  null_global_impl()
+    : ptr_(0)
+  {
+  }
+
+  // Destructor automatically cleans up the global.
+  ~null_global_impl()
+  {
+    delete ptr_;
+  }
+
+  static null_global_impl instance_;
+  T* ptr_;
+};
+
+template <typename T>
+null_global_impl<T> null_global_impl<T>::instance_;
+
+template <typename T>
+T& null_global()
+{
+  if (null_global_impl<T>::instance_.ptr_ == 0)
+    null_global_impl<T>::instance_.ptr_ = new T;
+  return *null_global_impl<T>::instance_.ptr_;
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_NULL_GLOBAL_HPP
diff --git a/include/boost/asio/detail/null_reactor.hpp b/include/boost/asio/detail/null_reactor.hpp
index 2cfce63a4c..30a07390a7 100644
--- a/include/boost/asio/detail/null_reactor.hpp
+++ b/include/boost/asio/detail/null_reactor.hpp
@@ -17,9 +17,10 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#if defined(BOOST_ASIO_HAS_IOCP) || defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/detail/scheduler_operation.hpp>
+#include <boost/asio/execution_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -28,12 +29,12 @@ namespace asio {
 namespace detail {
 
 class null_reactor
-  : public boost::asio::detail::service_base<null_reactor>
+  : public execution_context_service_base<null_reactor>
 {
 public:
   // Constructor.
-  null_reactor(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<null_reactor>(io_service)
+  null_reactor(boost::asio::execution_context& ctx)
+    : execution_context_service_base<null_reactor>(ctx)
   {
   }
 
@@ -43,12 +44,12 @@ class null_reactor
   }
 
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
   }
 
   // No-op because should never be called.
-  void run(bool /*block*/, op_queue<operation>& /*ops*/)
+  void run(long /*usec*/, op_queue<scheduler_operation>& /*ops*/)
   {
   }
 
@@ -64,6 +65,6 @@ class null_reactor
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#endif // defined(BOOST_ASIO_HAS_IOCP) || defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #endif // BOOST_ASIO_DETAIL_NULL_REACTOR_HPP
diff --git a/include/boost/asio/detail/null_socket_service.hpp b/include/boost/asio/detail/null_socket_service.hpp
index bf06ebb545..73a11cf9e8 100644
--- a/include/boost/asio/detail/null_socket_service.hpp
+++ b/include/boost/asio/detail/null_socket_service.hpp
@@ -21,7 +21,7 @@
 
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/socket_base.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 
@@ -32,7 +32,8 @@ namespace asio {
 namespace detail {
 
 template <typename Protocol>
-class null_socket_service
+class null_socket_service :
+  public service_base<null_socket_service<Protocol> >
 {
 public:
   // The protocol type.
@@ -50,13 +51,14 @@ class null_socket_service
   };
 
   // Constructor.
-  null_socket_service(boost::asio::io_service& io_service)
-    : io_service_(io_service)
+  null_socket_service(boost::asio::io_context& io_context)
+    : service_base<null_socket_service<Protocol> >(io_context),
+      io_context_(io_context)
   {
   }
 
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
   }
 
@@ -119,6 +121,14 @@ class null_socket_service
     return ec;
   }
 
+  // Release ownership of the socket.
+  native_handle_type release(implementation_type&,
+      boost::system::error_code& ec)
+  {
+    ec = boost::asio::error::operation_not_supported;
+    return 0;
+  }
+
   // Get the native socket representation.
   native_handle_type native_handle(implementation_type&)
   {
@@ -269,7 +279,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Start an asynchronous wait until data can be sent without blocking.
@@ -279,7 +289,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Receive some data from the peer. Returns the number of bytes received.
@@ -307,7 +317,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Wait until data can be received without blocking.
@@ -317,7 +327,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Receive some data with associated flags. Returns the number of bytes
@@ -349,7 +359,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Wait until data can be received without blocking.
@@ -360,7 +370,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Send a datagram to the specified endpoint. Returns the number of bytes
@@ -392,7 +402,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Start an asynchronous wait until data can be sent without blocking.
@@ -402,7 +412,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Receive a datagram with the endpoint of the sender. Returns the number of
@@ -435,7 +445,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Wait until data can be received without blocking.
@@ -446,7 +456,7 @@ class null_socket_service
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.post(detail::bind_handler(handler, ec, bytes_transferred));
+    io_context_.post(detail::bind_handler(handler, ec, bytes_transferred));
   }
 
   // Accept a new connection.
@@ -465,7 +475,7 @@ class null_socket_service
       endpoint_type*, Handler& handler)
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
-    io_service_.post(detail::bind_handler(handler, ec));
+    io_context_.post(detail::bind_handler(handler, ec));
   }
 
   // Connect the socket to the specified endpoint.
@@ -482,11 +492,11 @@ class null_socket_service
       const endpoint_type&, Handler& handler)
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
-    io_service_.post(detail::bind_handler(handler, ec));
+    io_context_.post(detail::bind_handler(handler, ec));
   }
 
 private:
-  boost::asio::io_service& io_service_;
+  boost::asio::io_context& io_context_;
 };
 
 } // namespace detail
diff --git a/include/boost/asio/detail/null_thread.hpp b/include/boost/asio/detail/null_thread.hpp
index 5e9b458638..bdb9912be3 100644
--- a/include/boost/asio/detail/null_thread.hpp
+++ b/include/boost/asio/detail/null_thread.hpp
@@ -50,6 +50,12 @@ class null_thread
   void join()
   {
   }
+
+  // Get number of CPUs.
+  static std::size_t hardware_concurrency()
+  {
+    return 1;
+  }
 };
 
 } // namespace detail
diff --git a/include/boost/asio/detail/object_pool.hpp b/include/boost/asio/detail/object_pool.hpp
index 692efed09d..3affeb8dab 100644
--- a/include/boost/asio/detail/object_pool.hpp
+++ b/include/boost/asio/detail/object_pool.hpp
@@ -35,6 +35,12 @@ class object_pool_access
     return new Object;
   }
 
+  template <typename Object, typename Arg>
+  static Object* create(Arg arg)
+  {
+    return new Object(arg);
+  }
+
   template <typename Object>
   static void destroy(Object* o)
   {
@@ -97,6 +103,25 @@ class object_pool
     return o;
   }
 
+  // Allocate a new object with an argument.
+  template <typename Arg>
+  Object* alloc(Arg arg)
+  {
+    Object* o = free_list_;
+    if (o)
+      free_list_ = object_pool_access::next(free_list_);
+    else
+      o = object_pool_access::create<Object>(arg);
+
+    object_pool_access::next(o) = live_list_;
+    object_pool_access::prev(o) = 0;
+    if (live_list_)
+      object_pool_access::prev(live_list_) = o;
+    live_list_ = o;
+
+    return o;
+  }
+
   // Free an object. Moves it to the free list. No destructors are run.
   void free(Object* o)
   {
diff --git a/include/boost/asio/detail/operation.hpp b/include/boost/asio/detail/operation.hpp
index a186a1f4d8..be62d12514 100644
--- a/include/boost/asio/detail/operation.hpp
+++ b/include/boost/asio/detail/operation.hpp
@@ -20,7 +20,7 @@
 #if defined(BOOST_ASIO_HAS_IOCP)
 # include <boost/asio/detail/win_iocp_operation.hpp>
 #else
-# include <boost/asio/detail/task_io_service_operation.hpp>
+# include <boost/asio/detail/scheduler_operation.hpp>
 #endif
 
 namespace boost {
@@ -30,7 +30,7 @@ namespace detail {
 #if defined(BOOST_ASIO_HAS_IOCP)
 typedef win_iocp_operation operation;
 #else
-typedef task_io_service_operation operation;
+typedef scheduler_operation operation;
 #endif
 
 } // namespace detail
diff --git a/include/boost/asio/detail/posix_event.hpp b/include/boost/asio/detail/posix_event.hpp
index 4eae96e2a8..970f298638 100644
--- a/include/boost/asio/detail/posix_event.hpp
+++ b/include/boost/asio/detail/posix_event.hpp
@@ -108,6 +108,39 @@ class posix_event
     }
   }
 
+  // Timed wait for the event to become signalled.
+  template <typename Lock>
+  bool wait_for_usec(Lock& lock, long usec)
+  {
+    BOOST_ASIO_ASSERT(lock.locked());
+    if ((state_ & 1) == 0)
+    {
+      state_ += 2;
+      timespec ts;
+#if (defined(__MACH__) && defined(__APPLE__)) \
+      || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
+      ts.tv_sec = usec / 1000000;
+      ts.tv_nsec = (usec % 1000000) * 1000;
+      ::pthread_cond_timedwait_relative_np(
+          &cond_, &lock.mutex().mutex_, &ts); // Ignore EINVAL.
+#else // (defined(__MACH__) && defined(__APPLE__))
+      // || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
+      if (::clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
+      {
+        ts.tv_sec += usec / 1000000;
+        ts.tv_nsec = (usec % 1000000) * 1000;
+        ts.tv_sec += ts.tv_nsec / 1000000000;
+        ts.tv_nsec = ts.tv_nsec % 1000000000;
+        ::pthread_cond_timedwait(&cond_,
+            &lock.mutex().mutex_, &ts); // Ignore EINVAL.
+      }
+#endif // (defined(__MACH__) && defined(__APPLE__))
+       // || (defined(__ANDROID__) && (__ANDROID_API__ < 21))
+      state_ -= 2;
+    }
+    return (state_ & 1) != 0;
+  }
+
 private:
   ::pthread_cond_t cond_;
   std::size_t state_;
diff --git a/include/boost/asio/detail/posix_global.hpp b/include/boost/asio/detail/posix_global.hpp
new file mode 100644
index 0000000000..463809fc29
--- /dev/null
+++ b/include/boost/asio/detail/posix_global.hpp
@@ -0,0 +1,82 @@
+//
+// detail/posix_global.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_POSIX_GLOBAL_HPP
+#define BOOST_ASIO_DETAIL_POSIX_GLOBAL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_PTHREADS)
+
+#include <exception>
+#include <pthread.h>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T>
+struct posix_global_impl
+{
+  // Helper function to perform initialisation.
+  static void do_init()
+  {
+    instance_.static_ptr_ = instance_.ptr_ = new T;
+  }
+
+  // Destructor automatically cleans up the global.
+  ~posix_global_impl()
+  {
+    delete static_ptr_;
+  }
+
+  static ::pthread_once_t init_once_;
+  static T* static_ptr_;
+  static posix_global_impl instance_;
+  T* ptr_;
+};
+
+template <typename T>
+::pthread_once_t posix_global_impl<T>::init_once_ = PTHREAD_ONCE_INIT;
+
+template <typename T>
+T* posix_global_impl<T>::static_ptr_ = 0;
+
+template <typename T>
+posix_global_impl<T> posix_global_impl<T>::instance_;
+
+template <typename T>
+T& posix_global()
+{
+  int result = ::pthread_once(
+      &posix_global_impl<T>::init_once_,
+      &posix_global_impl<T>::do_init);
+
+  if (result != 0)
+    std::terminate();
+
+  return *posix_global_impl<T>::instance_.ptr_;
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // defined(BOOST_ASIO_HAS_PTHREADS)
+
+#endif // BOOST_ASIO_DETAIL_POSIX_GLOBAL_HPP
diff --git a/include/boost/asio/detail/posix_thread.hpp b/include/boost/asio/detail/posix_thread.hpp
index ddf5ba46f3..985e14028f 100644
--- a/include/boost/asio/detail/posix_thread.hpp
+++ b/include/boost/asio/detail/posix_thread.hpp
@@ -19,6 +19,7 @@
 
 #if defined(BOOST_ASIO_HAS_PTHREADS)
 
+#include <cstddef>
 #include <pthread.h>
 #include <boost/asio/detail/noncopyable.hpp>
 
@@ -51,6 +52,9 @@ class posix_thread
   // Wait for the thread to exit.
   BOOST_ASIO_DECL void join();
 
+  // Get number of CPUs.
+  BOOST_ASIO_DECL static std::size_t hardware_concurrency();
+
 private:
   friend void* boost_asio_detail_posix_thread_function(void* arg);
 
diff --git a/include/boost/asio/detail/push_options.hpp b/include/boost/asio/detail/push_options.hpp
index ae189c0519..f6cbafd599 100644
--- a/include/boost/asio/detail/push_options.hpp
+++ b/include/boost/asio/detail/push_options.hpp
@@ -135,6 +135,10 @@
 # pragma warning (disable:4512)
 # pragma warning (disable:4610)
 # pragma warning (disable:4675)
+# if (_MSC_VER < 1600)
+// Visual Studio 2008 generates spurious warnings about unused parameters.
+#  pragma warning (disable:4100)
+# endif // (_MSC_VER < 1600)
 # if defined(_M_IX86) && defined(_Wp64)
 // The /Wp64 option is broken. If you want to check 64 bit portability, use a
 // 64 bit compiler!
diff --git a/include/boost/asio/detail/reactive_descriptor_service.hpp b/include/boost/asio/detail/reactive_descriptor_service.hpp
index 3d6d1e98c8..f413edbc7b 100644
--- a/include/boost/asio/detail/reactive_descriptor_service.hpp
+++ b/include/boost/asio/detail/reactive_descriptor_service.hpp
@@ -22,17 +22,19 @@
   && !defined(__CYGWIN__)
 
 #include <boost/asio/buffer.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/descriptor_ops.hpp>
 #include <boost/asio/detail/descriptor_read_op.hpp>
 #include <boost/asio/detail/descriptor_write_op.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/reactive_null_buffers_op.hpp>
+#include <boost/asio/detail/reactive_wait_op.hpp>
 #include <boost/asio/detail/reactor.hpp>
+#include <boost/asio/posix/descriptor_base.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -40,7 +42,8 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-class reactive_descriptor_service
+class reactive_descriptor_service :
+  public service_base<reactive_descriptor_service>
 {
 public:
   // The native type of a descriptor.
@@ -74,10 +77,10 @@ class reactive_descriptor_service
 
   // Constructor.
   BOOST_ASIO_DECL reactive_descriptor_service(
-      boost::asio::io_service& io_service);
+      boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Construct a new descriptor implementation.
   BOOST_ASIO_DECL void construct(implementation_type& impl);
@@ -162,6 +165,71 @@ class reactive_descriptor_service
     return ec;
   }
 
+  // Wait for the descriptor to become ready to read, ready to write, or to have
+  // pending error conditions.
+  boost::system::error_code wait(implementation_type& impl,
+      posix::descriptor_base::wait_type w, boost::system::error_code& ec)
+  {
+    switch (w)
+    {
+    case posix::descriptor_base::wait_read:
+      descriptor_ops::poll_read(impl.descriptor_, impl.state_, ec);
+      break;
+    case posix::descriptor_base::wait_write:
+      descriptor_ops::poll_write(impl.descriptor_, impl.state_, ec);
+      break;
+    case posix::descriptor_base::wait_error:
+      descriptor_ops::poll_error(impl.descriptor_, impl.state_, ec);
+      break;
+    default:
+      ec = boost::asio::error::invalid_argument;
+      break;
+    }
+
+    return ec;
+  }
+
+  // Asynchronously wait for the descriptor to become ready to read, ready to
+  // write, or to have pending error conditions.
+  template <typename Handler>
+  void async_wait(implementation_type& impl,
+      posix::descriptor_base::wait_type w, Handler& handler)
+  {
+    bool is_continuation =
+      boost_asio_handler_cont_helpers::is_continuation(handler);
+
+    // Allocate and construct an operation to wrap the handler.
+    typedef reactive_wait_op<Handler> op;
+    typename op::ptr p = { boost::asio::detail::addressof(handler),
+      op::ptr::allocate(handler), 0 };
+    p.p = new (p.v) op(handler);
+
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
+          &impl, impl.descriptor_, "async_wait"));
+
+    int op_type;
+    switch (w)
+    {
+    case posix::descriptor_base::wait_read:
+        op_type = reactor::read_op;
+        break;
+    case posix::descriptor_base::wait_write:
+        op_type = reactor::write_op;
+        break;
+    case posix::descriptor_base::wait_error:
+        op_type = reactor::except_op;
+        break;
+      default:
+        p.p->ec_ = boost::asio::error::invalid_argument;
+        reactor_.post_immediate_completion(p.p, is_continuation);
+        p.v = p.p = 0;
+        return;
+    }
+
+    start_op(impl, op_type, p.p, is_continuation, false, false);
+    p.v = p.p = 0;
+  }
+
   // Write some data to the descriptor.
   template <typename ConstBufferSequence>
   size_t write_some(implementation_type& impl,
@@ -196,11 +264,11 @@ class reactive_descriptor_service
     // Allocate and construct an operation to wrap the handler.
     typedef descriptor_write_op<ConstBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.descriptor_, buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "descriptor", &impl, "async_write_some"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
+          &impl, impl.descriptor_, "async_write_some"));
 
     start_op(impl, reactor::write_op, p.p, is_continuation, true,
         buffer_sequence_adapter<boost::asio::const_buffer,
@@ -219,12 +287,11 @@ class reactive_descriptor_service
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "descriptor",
-          &impl, "async_write_some(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
+          &impl, impl.descriptor_, "async_write_some(null_buffers)"));
 
     start_op(impl, reactor::write_op, p.p, is_continuation, false, false);
     p.v = p.p = 0;
@@ -264,11 +331,11 @@ class reactive_descriptor_service
     // Allocate and construct an operation to wrap the handler.
     typedef descriptor_read_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.descriptor_, buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "descriptor", &impl, "async_read_some"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
+          &impl, impl.descriptor_, "async_read_some"));
 
     start_op(impl, reactor::read_op, p.p, is_continuation, true,
         buffer_sequence_adapter<boost::asio::mutable_buffer,
@@ -287,12 +354,11 @@ class reactive_descriptor_service
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "descriptor",
-          &impl, "async_read_some(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "descriptor",
+          &impl, impl.descriptor_, "async_read_some(null_buffers)"));
 
     start_op(impl, reactor::read_op, p.p, is_continuation, false, false);
     p.v = p.p = 0;
diff --git a/include/boost/asio/detail/reactive_null_buffers_op.hpp b/include/boost/asio/detail/reactive_null_buffers_op.hpp
index 4b1c7fedbf..0983b8a52e 100644
--- a/include/boost/asio/detail/reactive_null_buffers_op.hpp
+++ b/include/boost/asio/detail/reactive_null_buffers_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -39,22 +39,24 @@ class reactive_null_buffers_op : public reactor_op
         &reactive_null_buffers_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static bool do_perform(reactor_op*)
+  static status do_perform(reactor_op*)
   {
-    return true;
+    return done;
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     reactive_null_buffers_op* o(static_cast<reactive_null_buffers_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -72,7 +74,7 @@ class reactive_null_buffers_op : public reactor_op
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/reactive_serial_port_service.hpp b/include/boost/asio/detail/reactive_serial_port_service.hpp
index 4976fbd08e..225f0828f5 100644
--- a/include/boost/asio/detail/reactive_serial_port_service.hpp
+++ b/include/boost/asio/detail/reactive_serial_port_service.hpp
@@ -23,7 +23,7 @@
 
 #include <string>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/serial_port_base.hpp>
 #include <boost/asio/detail/descriptor_ops.hpp>
 #include <boost/asio/detail/reactive_descriptor_service.hpp>
@@ -35,7 +35,8 @@ namespace asio {
 namespace detail {
 
 // Extend reactive_descriptor_service to provide serial port support.
-class reactive_serial_port_service
+class reactive_serial_port_service :
+  public service_base<reactive_serial_port_service>
 {
 public:
   // The native type of a serial port.
@@ -45,10 +46,10 @@ class reactive_serial_port_service
   typedef reactive_descriptor_service::implementation_type implementation_type;
 
   BOOST_ASIO_DECL reactive_serial_port_service(
-      boost::asio::io_service& io_service);
+      boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Construct a new serial port implementation.
   void construct(implementation_type& impl)
@@ -190,8 +191,8 @@ class reactive_serial_port_service
   static boost::system::error_code store_option(const void* option,
       termios& storage, boost::system::error_code& ec)
   {
-    return static_cast<const SettableSerialPortOption*>(option)->store(
-        storage, ec);
+    static_cast<const SettableSerialPortOption*>(option)->store(storage, ec);
+    return ec;
   }
 
   // Helper function to set a serial port option.
@@ -208,7 +209,8 @@ class reactive_serial_port_service
   static boost::system::error_code load_option(void* option,
       const termios& storage, boost::system::error_code& ec)
   {
-    return static_cast<GettableSerialPortOption*>(option)->load(storage, ec);
+    static_cast<GettableSerialPortOption*>(option)->load(storage, ec);
+    return ec;
   }
 
   // Helper function to get a serial port option.
diff --git a/include/boost/asio/detail/reactive_socket_accept_op.hpp b/include/boost/asio/detail/reactive_socket_accept_op.hpp
index fec6bddb55..ca996b2ab5 100644
--- a/include/boost/asio/detail/reactive_socket_accept_op.hpp
+++ b/include/boost/asio/detail/reactive_socket_accept_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_holder.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
@@ -42,40 +42,48 @@ class reactive_socket_accept_op_base : public reactor_op
       state_(state),
       peer_(peer),
       protocol_(protocol),
-      peer_endpoint_(peer_endpoint)
+      peer_endpoint_(peer_endpoint),
+      addrlen_(peer_endpoint ? peer_endpoint->capacity() : 0)
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     reactive_socket_accept_op_base* o(
         static_cast<reactive_socket_accept_op_base*>(base));
 
-    std::size_t addrlen = o->peer_endpoint_ ? o->peer_endpoint_->capacity() : 0;
     socket_type new_socket = invalid_socket;
-    bool result = socket_ops::non_blocking_accept(o->socket_,
-          o->state_, o->peer_endpoint_ ? o->peer_endpoint_->data() : 0,
-          o->peer_endpoint_ ? &addrlen : 0, o->ec_, new_socket);
+    status result = socket_ops::non_blocking_accept(o->socket_,
+        o->state_, o->peer_endpoint_ ? o->peer_endpoint_->data() : 0,
+        o->peer_endpoint_ ? &o->addrlen_ : 0, o->ec_, new_socket)
+    ? done : not_done;
+    o->new_socket_.reset(new_socket);
 
-    // On success, assign new connection to peer socket object.
-    if (new_socket != invalid_socket)
-    {
-      socket_holder new_socket_holder(new_socket);
-      if (o->peer_endpoint_)
-        o->peer_endpoint_->resize(addrlen);
-      if (!o->peer_.assign(o->protocol_, new_socket, o->ec_))
-        new_socket_holder.release();
-    }
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_accept", o->ec_));
 
     return result;
   }
 
+  void do_assign()
+  {
+    if (new_socket_.get() != invalid_socket)
+    {
+      if (peer_endpoint_)
+        peer_endpoint_->resize(addrlen_);
+      peer_.assign(protocol_, new_socket_.get(), ec_);
+      if (!ec_)
+        new_socket_.release();
+    }
+  }
+
 private:
   socket_type socket_;
   socket_ops::state_type state_;
+  socket_holder new_socket_;
   Socket& peer_;
   Protocol protocol_;
   typename Protocol::endpoint* peer_endpoint_;
+  std::size_t addrlen_;
 };
 
 template <typename Socket, typename Protocol, typename Handler>
@@ -92,17 +100,23 @@ class reactive_socket_accept_op :
         protocol, peer_endpoint, &reactive_socket_accept_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     reactive_socket_accept_op* o(static_cast<reactive_socket_accept_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
+
+    // On success, assign new connection to peer socket object.
+    if (owner)
+      o->do_assign();
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -120,7 +134,72 @@ class reactive_socket_accept_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
+      BOOST_ASIO_HANDLER_INVOCATION_END;
+    }
+  }
+
+private:
+  Handler handler_;
+};
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+
+template <typename Protocol, typename Handler>
+class reactive_socket_move_accept_op :
+  private Protocol::socket,
+  public reactive_socket_accept_op_base<typename Protocol::socket, Protocol>
+{
+public:
+  BOOST_ASIO_DEFINE_HANDLER_PTR(reactive_socket_move_accept_op);
+
+  reactive_socket_move_accept_op(io_context& ioc, socket_type socket,
+      socket_ops::state_type state, const Protocol& protocol,
+      typename Protocol::endpoint* peer_endpoint, Handler& handler)
+    : Protocol::socket(ioc),
+      reactive_socket_accept_op_base<typename Protocol::socket, Protocol>(
+        socket, state, *this, protocol, peer_endpoint,
+        &reactive_socket_move_accept_op::do_complete),
+      handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
+  {
+    handler_work<Handler>::start(handler_);
+  }
+
+  static void do_complete(void* owner, operation* base,
+      const boost::system::error_code& /*ec*/,
+      std::size_t /*bytes_transferred*/)
+  {
+    // Take ownership of the handler object.
+    reactive_socket_move_accept_op* o(
+        static_cast<reactive_socket_move_accept_op*>(base));
+    ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
+
+    // On success, assign new connection to peer socket object.
+    if (owner)
+      o->do_assign();
+
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
+
+    // Make a copy of the handler so that the memory can be deallocated before
+    // the upcall is made. Even if we're not about to make an upcall, a
+    // sub-object of the handler may be the true owner of the memory associated
+    // with the handler. Consequently, a local copy of the handler is required
+    // to ensure that any owning sub-object remains valid until after we have
+    // deallocated the memory here.
+    detail::move_binder2<Handler,
+      boost::system::error_code, typename Protocol::socket>
+        handler(0, BOOST_ASIO_MOVE_CAST(Handler)(o->handler_), o->ec_,
+          BOOST_ASIO_MOVE_CAST(typename Protocol::socket)(*o));
+    p.h = boost::asio::detail::addressof(handler.handler_);
+    p.reset();
+
+    // Make the upcall if required.
+    if (owner)
+    {
+      fenced_block b(fenced_block::half);
+      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
@@ -129,6 +208,8 @@ class reactive_socket_accept_op :
   Handler handler_;
 };
 
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/detail/reactive_socket_connect_op.hpp b/include/boost/asio/detail/reactive_socket_connect_op.hpp
index 809d63b7ae..410da203ad 100644
--- a/include/boost/asio/detail/reactive_socket_connect_op.hpp
+++ b/include/boost/asio/detail/reactive_socket_connect_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 
@@ -38,12 +38,17 @@ class reactive_socket_connect_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     reactive_socket_connect_op_base* o(
         static_cast<reactive_socket_connect_op_base*>(base));
 
-    return socket_ops::non_blocking_connect(o->socket_, o->ec_);
+    status result = socket_ops::non_blocking_connect(
+        o->socket_, o->ec_) ? done : not_done;
+
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_connect", o->ec_));
+
+    return result;
   }
 
 private:
@@ -61,9 +66,10 @@ class reactive_socket_connect_op : public reactive_socket_connect_op_base
         &reactive_socket_connect_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
@@ -71,8 +77,9 @@ class reactive_socket_connect_op : public reactive_socket_connect_op_base
     reactive_socket_connect_op* o
       (static_cast<reactive_socket_connect_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -90,7 +97,7 @@ class reactive_socket_connect_op : public reactive_socket_connect_op_base
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/reactive_socket_recv_op.hpp b/include/boost/asio/detail/reactive_socket_recv_op.hpp
index 751160c48f..ea7d84a0c5 100644
--- a/include/boost/asio/detail/reactive_socket_recv_op.hpp
+++ b/include/boost/asio/detail/reactive_socket_recv_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 
@@ -44,7 +44,7 @@ class reactive_socket_recv_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     reactive_socket_recv_op_base* o(
         static_cast<reactive_socket_recv_op_base*>(base));
@@ -52,10 +52,20 @@ class reactive_socket_recv_op_base : public reactor_op
     buffer_sequence_adapter<boost::asio::mutable_buffer,
         MutableBufferSequence> bufs(o->buffers_);
 
-    return socket_ops::non_blocking_recv(o->socket_,
+    status result = socket_ops::non_blocking_recv(o->socket_,
         bufs.buffers(), bufs.count(), o->flags_,
         (o->state_ & socket_ops::stream_oriented) != 0,
-        o->ec_, o->bytes_transferred_);
+        o->ec_, o->bytes_transferred_) ? done : not_done;
+
+    if (result == done)
+      if ((o->state_ & socket_ops::stream_oriented) != 0)
+        if (o->bytes_transferred_ == 0)
+          result = done_and_exhausted;
+
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_recv",
+          o->ec_, o->bytes_transferred_));
+
+    return result;
   }
 
 private:
@@ -79,17 +89,19 @@ class reactive_socket_recv_op :
         buffers, flags, &reactive_socket_recv_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     reactive_socket_recv_op* o(static_cast<reactive_socket_recv_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -107,7 +119,7 @@ class reactive_socket_recv_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/reactive_socket_recvfrom_op.hpp b/include/boost/asio/detail/reactive_socket_recvfrom_op.hpp
index 14829a0d75..9631465f24 100644
--- a/include/boost/asio/detail/reactive_socket_recvfrom_op.hpp
+++ b/include/boost/asio/detail/reactive_socket_recvfrom_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 
@@ -45,7 +45,7 @@ class reactive_socket_recvfrom_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     reactive_socket_recvfrom_op_base* o(
         static_cast<reactive_socket_recvfrom_op_base*>(base));
@@ -54,14 +54,17 @@ class reactive_socket_recvfrom_op_base : public reactor_op
         MutableBufferSequence> bufs(o->buffers_);
 
     std::size_t addr_len = o->sender_endpoint_.capacity();
-    bool result = socket_ops::non_blocking_recvfrom(o->socket_,
+    status result = socket_ops::non_blocking_recvfrom(o->socket_,
         bufs.buffers(), bufs.count(), o->flags_,
         o->sender_endpoint_.data(), &addr_len,
-        o->ec_, o->bytes_transferred_);
+        o->ec_, o->bytes_transferred_) ? done : not_done;
 
     if (result && !o->ec_)
       o->sender_endpoint_.resize(addr_len);
 
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_recvfrom",
+          o->ec_, o->bytes_transferred_));
+
     return result;
   }
 
@@ -88,9 +91,10 @@ class reactive_socket_recvfrom_op :
         &reactive_socket_recvfrom_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
@@ -98,8 +102,9 @@ class reactive_socket_recvfrom_op :
     reactive_socket_recvfrom_op* o(
         static_cast<reactive_socket_recvfrom_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -117,7 +122,7 @@ class reactive_socket_recvfrom_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/reactive_socket_recvmsg_op.hpp b/include/boost/asio/detail/reactive_socket_recvmsg_op.hpp
index fed5d01098..c48b1aba7e 100644
--- a/include/boost/asio/detail/reactive_socket_recvmsg_op.hpp
+++ b/include/boost/asio/detail/reactive_socket_recvmsg_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/socket_base.hpp>
@@ -45,7 +45,7 @@ class reactive_socket_recvmsg_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     reactive_socket_recvmsg_op_base* o(
         static_cast<reactive_socket_recvmsg_op_base*>(base));
@@ -53,10 +53,15 @@ class reactive_socket_recvmsg_op_base : public reactor_op
     buffer_sequence_adapter<boost::asio::mutable_buffer,
         MutableBufferSequence> bufs(o->buffers_);
 
-    return socket_ops::non_blocking_recvmsg(o->socket_,
+    status result = socket_ops::non_blocking_recvmsg(o->socket_,
         bufs.buffers(), bufs.count(),
         o->in_flags_, o->out_flags_,
-        o->ec_, o->bytes_transferred_);
+        o->ec_, o->bytes_transferred_) ? done : not_done;
+
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_recvmsg",
+          o->ec_, o->bytes_transferred_));
+
+    return result;
   }
 
 private:
@@ -80,9 +85,10 @@ class reactive_socket_recvmsg_op :
         in_flags, out_flags, &reactive_socket_recvmsg_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
@@ -90,8 +96,9 @@ class reactive_socket_recvmsg_op :
     reactive_socket_recvmsg_op* o(
         static_cast<reactive_socket_recvmsg_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -109,7 +116,7 @@ class reactive_socket_recvmsg_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/reactive_socket_send_op.hpp b/include/boost/asio/detail/reactive_socket_send_op.hpp
index 776117b6f7..01bb58f9ae 100644
--- a/include/boost/asio/detail/reactive_socket_send_op.hpp
+++ b/include/boost/asio/detail/reactive_socket_send_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 
@@ -34,16 +34,17 @@ class reactive_socket_send_op_base : public reactor_op
 {
 public:
   reactive_socket_send_op_base(socket_type socket,
-      const ConstBufferSequence& buffers,
+      socket_ops::state_type state, const ConstBufferSequence& buffers,
       socket_base::message_flags flags, func_type complete_func)
     : reactor_op(&reactive_socket_send_op_base::do_perform, complete_func),
       socket_(socket),
+      state_(state),
       buffers_(buffers),
       flags_(flags)
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     reactive_socket_send_op_base* o(
         static_cast<reactive_socket_send_op_base*>(base));
@@ -51,13 +52,24 @@ class reactive_socket_send_op_base : public reactor_op
     buffer_sequence_adapter<boost::asio::const_buffer,
         ConstBufferSequence> bufs(o->buffers_);
 
-    return socket_ops::non_blocking_send(o->socket_,
+    status result = socket_ops::non_blocking_send(o->socket_,
           bufs.buffers(), bufs.count(), o->flags_,
-          o->ec_, o->bytes_transferred_);
+          o->ec_, o->bytes_transferred_) ? done : not_done;
+
+    if (result == done)
+      if ((o->state_ & socket_ops::stream_oriented) != 0)
+        if (o->bytes_transferred_ < bufs.total_size())
+          result = done_and_exhausted;
+
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_send",
+          o->ec_, o->bytes_transferred_));
+
+    return result;
   }
 
 private:
   socket_type socket_;
+  socket_ops::state_type state_;
   ConstBufferSequence buffers_;
   socket_base::message_flags flags_;
 };
@@ -70,23 +82,25 @@ class reactive_socket_send_op :
   BOOST_ASIO_DEFINE_HANDLER_PTR(reactive_socket_send_op);
 
   reactive_socket_send_op(socket_type socket,
-      const ConstBufferSequence& buffers,
+      socket_ops::state_type state, const ConstBufferSequence& buffers,
       socket_base::message_flags flags, Handler& handler)
     : reactive_socket_send_op_base<ConstBufferSequence>(socket,
-        buffers, flags, &reactive_socket_send_op::do_complete),
+        state, buffers, flags, &reactive_socket_send_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     reactive_socket_send_op* o(static_cast<reactive_socket_send_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -104,7 +118,7 @@ class reactive_socket_send_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/reactive_socket_sendto_op.hpp b/include/boost/asio/detail/reactive_socket_sendto_op.hpp
index 134c767c86..47a2656e22 100644
--- a/include/boost/asio/detail/reactive_socket_sendto_op.hpp
+++ b/include/boost/asio/detail/reactive_socket_sendto_op.hpp
@@ -16,10 +16,10 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 
@@ -44,7 +44,7 @@ class reactive_socket_sendto_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     reactive_socket_sendto_op_base* o(
         static_cast<reactive_socket_sendto_op_base*>(base));
@@ -52,10 +52,15 @@ class reactive_socket_sendto_op_base : public reactor_op
     buffer_sequence_adapter<boost::asio::const_buffer,
         ConstBufferSequence> bufs(o->buffers_);
 
-    return socket_ops::non_blocking_sendto(o->socket_,
+    status result = socket_ops::non_blocking_sendto(o->socket_,
           bufs.buffers(), bufs.count(), o->flags_,
           o->destination_.data(), o->destination_.size(),
-          o->ec_, o->bytes_transferred_);
+          o->ec_, o->bytes_transferred_) ? done : not_done;
+
+    BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_sendto",
+          o->ec_, o->bytes_transferred_));
+
+    return result;
   }
 
 private:
@@ -79,17 +84,19 @@ class reactive_socket_sendto_op :
         buffers, endpoint, flags, &reactive_socket_sendto_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     reactive_socket_sendto_op* o(static_cast<reactive_socket_sendto_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -107,7 +114,7 @@ class reactive_socket_sendto_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/reactive_socket_service.hpp b/include/boost/asio/detail/reactive_socket_service.hpp
index d5a6e08eab..186cf35336 100644
--- a/include/boost/asio/detail/reactive_socket_service.hpp
+++ b/include/boost/asio/detail/reactive_socket_service.hpp
@@ -21,10 +21,10 @@
 
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/socket_base.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/reactive_null_buffers_op.hpp>
 #include <boost/asio/detail/reactive_socket_accept_op.hpp>
@@ -46,6 +46,7 @@ namespace detail {
 
 template <typename Protocol>
 class reactive_socket_service :
+  public service_base<reactive_socket_service<Protocol> >,
   public reactive_socket_service_base
 {
 public:
@@ -73,11 +74,18 @@ class reactive_socket_service :
   };
 
   // Constructor.
-  reactive_socket_service(boost::asio::io_service& io_service)
-    : reactive_socket_service_base(io_service)
+  reactive_socket_service(boost::asio::io_context& io_context)
+    : service_base<reactive_socket_service<Protocol> >(io_context),
+      reactive_socket_service_base(io_context)
   {
   }
 
+  // Destroy all user-defined handler objects owned by the service.
+  void shutdown()
+  {
+    this->base_shutdown();
+  }
+
   // Move-construct a new socket implementation.
   void move_construct(implementation_type& impl,
       implementation_type& other_impl)
@@ -196,6 +204,14 @@ class reactive_socket_service :
     return endpoint;
   }
 
+  // Disable sends or receives on the socket.
+  boost::system::error_code shutdown(base_implementation_type& impl,
+      socket_base::shutdown_type what, boost::system::error_code& ec)
+  {
+    socket_ops::shutdown(impl.socket_, what, ec);
+    return ec;
+  }
+
   // Send a datagram to the specified endpoint. Returns the number of bytes
   // sent.
   template <typename ConstBufferSequence>
@@ -217,7 +233,7 @@ class reactive_socket_service :
       boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_write(impl.socket_, impl.state_, ec);
+    socket_ops::poll_write(impl.socket_, impl.state_, -1, ec);
 
     return 0;
   }
@@ -237,11 +253,11 @@ class reactive_socket_service :
     typedef reactive_socket_sendto_op<ConstBufferSequence,
         endpoint_type, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.socket_, buffers, destination, flags, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_send_to"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_send_to"));
 
     start_op(impl, reactor::write_op, p.p, is_continuation, true, false);
     p.v = p.p = 0;
@@ -258,12 +274,11 @@ class reactive_socket_service :
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_send_to(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_send_to(null_buffers)"));
 
     start_op(impl, reactor::write_op, p.p, is_continuation, false, false);
     p.v = p.p = 0;
@@ -297,7 +312,7 @@ class reactive_socket_service :
       boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_read(impl.socket_, impl.state_, ec);
+    socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
 
     // Reset endpoint since it can be given no sensible value at this time.
     sender_endpoint = endpoint_type();
@@ -320,14 +335,13 @@ class reactive_socket_service :
     typedef reactive_socket_recvfrom_op<MutableBufferSequence,
         endpoint_type, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     int protocol = impl.protocol_.type();
     p.p = new (p.v) op(impl.socket_, protocol,
         buffers, sender_endpoint, flags, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_receive_from"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_receive_from"));
 
     start_op(impl,
         (flags & socket_base::message_out_of_band)
@@ -348,12 +362,11 @@ class reactive_socket_service :
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_receive_from(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_receive_from(null_buffers)"));
 
     // Reset endpoint since it can be given no sensible value at this time.
     sender_endpoint = endpoint_type();
@@ -387,15 +400,44 @@ class reactive_socket_service :
     {
       if (peer_endpoint)
         peer_endpoint->resize(addr_len);
-      if (!peer.assign(impl.protocol_, new_socket.get(), ec))
+      peer.assign(impl.protocol_, new_socket.get(), ec);
+      if (!ec)
         new_socket.release();
     }
 
     return ec;
   }
 
-  // Start an asynchronous accept. The peer and peer_endpoint objects
-  // must be valid until the accept's handler is invoked.
+#if defined(BOOST_ASIO_HAS_MOVE)
+  // Accept a new connection.
+  typename Protocol::socket accept(implementation_type& impl,
+      io_context* peer_io_context, endpoint_type* peer_endpoint,
+      boost::system::error_code& ec)
+  {
+    typename Protocol::socket peer(
+        peer_io_context ? *peer_io_context : io_context_);
+
+    std::size_t addr_len = peer_endpoint ? peer_endpoint->capacity() : 0;
+    socket_holder new_socket(socket_ops::sync_accept(impl.socket_,
+          impl.state_, peer_endpoint ? peer_endpoint->data() : 0,
+          peer_endpoint ? &addr_len : 0, ec));
+
+    // On success, assign new connection to peer socket object.
+    if (new_socket.get() != invalid_socket)
+    {
+      if (peer_endpoint)
+        peer_endpoint->resize(addr_len);
+      peer.assign(impl.protocol_, new_socket.get(), ec);
+      if (!ec)
+        new_socket.release();
+    }
+
+    return peer;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  // Start an asynchronous accept. The peer and peer_endpoint objects must be
+  // valid until the accept's handler is invoked.
   template <typename Socket, typename Handler>
   void async_accept(implementation_type& impl, Socket& peer,
       endpoint_type* peer_endpoint, Handler& handler)
@@ -406,17 +448,43 @@ class reactive_socket_service :
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_socket_accept_op<Socket, Protocol, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.socket_, impl.state_, peer,
         impl.protocol_, peer_endpoint, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_accept"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_accept"));
 
     start_accept_op(impl, p.p, is_continuation, peer.is_open());
     p.v = p.p = 0;
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+  // Start an asynchronous accept. The peer_endpoint object must be valid until
+  // the accept's handler is invoked.
+  template <typename Handler>
+  void async_accept(implementation_type& impl,
+      boost::asio::io_context* peer_io_context,
+      endpoint_type* peer_endpoint, Handler& handler)
+  {
+    bool is_continuation =
+      boost_asio_handler_cont_helpers::is_continuation(handler);
+
+    // Allocate and construct an operation to wrap the handler.
+    typedef reactive_socket_move_accept_op<Protocol, Handler> op;
+    typename op::ptr p = { boost::asio::detail::addressof(handler),
+      op::ptr::allocate(handler), 0 };
+    p.p = new (p.v) op(peer_io_context ? *peer_io_context : io_context_,
+        impl.socket_, impl.state_, impl.protocol_, peer_endpoint, handler);
+
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_accept"));
+
+    start_accept_op(impl, p.p, is_continuation, false);
+    p.v = p.p = 0;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
   // Connect the socket to the specified endpoint.
   boost::system::error_code connect(implementation_type& impl,
       const endpoint_type& peer_endpoint, boost::system::error_code& ec)
@@ -437,11 +505,11 @@ class reactive_socket_service :
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_socket_connect_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.socket_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_connect"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_connect"));
 
     start_connect_op(impl, p.p, is_continuation,
         peer_endpoint.data(), peer_endpoint.size());
diff --git a/include/boost/asio/detail/reactive_socket_service_base.hpp b/include/boost/asio/detail/reactive_socket_service_base.hpp
index fb2aa5d028..17c694a3cd 100644
--- a/include/boost/asio/detail/reactive_socket_service_base.hpp
+++ b/include/boost/asio/detail/reactive_socket_service_base.hpp
@@ -22,14 +22,15 @@
 
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/socket_base.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactive_null_buffers_op.hpp>
 #include <boost/asio/detail/reactive_socket_recv_op.hpp>
 #include <boost/asio/detail/reactive_socket_recvmsg_op.hpp>
 #include <boost/asio/detail/reactive_socket_send_op.hpp>
+#include <boost/asio/detail/reactive_wait_op.hpp>
 #include <boost/asio/detail/reactor.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_holder.hpp>
@@ -63,10 +64,10 @@ class reactive_socket_service_base
 
   // Constructor.
   BOOST_ASIO_DECL reactive_socket_service_base(
-      boost::asio::io_service& io_service);
+      boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void base_shutdown();
 
   // Construct a new socket implementation.
   BOOST_ASIO_DECL void construct(base_implementation_type& impl);
@@ -93,6 +94,10 @@ class reactive_socket_service_base
   BOOST_ASIO_DECL boost::system::error_code close(
       base_implementation_type& impl, boost::system::error_code& ec);
 
+  // Release ownership of the socket.
+  BOOST_ASIO_DECL socket_type release(
+      base_implementation_type& impl, boost::system::error_code& ec);
+
   // Get the native socket representation.
   native_handle_type native_handle(base_implementation_type& impl)
   {
@@ -163,14 +168,71 @@ class reactive_socket_service_base
     return ec;
   }
 
-  // Disable sends or receives on the socket.
-  boost::system::error_code shutdown(base_implementation_type& impl,
-      socket_base::shutdown_type what, boost::system::error_code& ec)
+  // Wait for the socket to become ready to read, ready to write, or to have
+  // pending error conditions.
+  boost::system::error_code wait(base_implementation_type& impl,
+      socket_base::wait_type w, boost::system::error_code& ec)
   {
-    socket_ops::shutdown(impl.socket_, what, ec);
+    switch (w)
+    {
+    case socket_base::wait_read:
+      socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
+      break;
+    case socket_base::wait_write:
+      socket_ops::poll_write(impl.socket_, impl.state_, -1, ec);
+      break;
+    case socket_base::wait_error:
+      socket_ops::poll_error(impl.socket_, impl.state_, -1, ec);
+      break;
+    default:
+      ec = boost::asio::error::invalid_argument;
+      break;
+    }
+
     return ec;
   }
 
+  // Asynchronously wait for the socket to become ready to read, ready to
+  // write, or to have pending error conditions.
+  template <typename Handler>
+  void async_wait(base_implementation_type& impl,
+      socket_base::wait_type w, Handler& handler)
+  {
+    bool is_continuation =
+      boost_asio_handler_cont_helpers::is_continuation(handler);
+
+    // Allocate and construct an operation to wrap the handler.
+    typedef reactive_wait_op<Handler> op;
+    typename op::ptr p = { boost::asio::detail::addressof(handler),
+      op::ptr::allocate(handler), 0 };
+    p.p = new (p.v) op(handler);
+
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_wait"));
+
+    int op_type;
+    switch (w)
+    {
+      case socket_base::wait_read:
+        op_type = reactor::read_op;
+        break;
+      case socket_base::wait_write:
+        op_type = reactor::write_op;
+        break;
+      case socket_base::wait_error:
+        op_type = reactor::except_op;
+        break;
+      default:
+        p.p->ec_ = boost::asio::error::invalid_argument;
+        reactor_.post_immediate_completion(p.p, is_continuation);
+        p.v = p.p = 0;
+        return;
+    }
+
+    start_op(impl, op_type, p.p, is_continuation, false, false);
+    p.v = p.p = 0;
+  }
+
   // Send the given data to the peer.
   template <typename ConstBufferSequence>
   size_t send(base_implementation_type& impl,
@@ -189,7 +251,7 @@ class reactive_socket_service_base
       socket_base::message_flags, boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_write(impl.socket_, impl.state_, ec);
+    socket_ops::poll_write(impl.socket_, impl.state_, -1, ec);
 
     return 0;
   }
@@ -207,11 +269,11 @@ class reactive_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_socket_send_op<ConstBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
-    p.p = new (p.v) op(impl.socket_, buffers, flags, handler);
+      op::ptr::allocate(handler), 0 };
+    p.p = new (p.v) op(impl.socket_, impl.state_, buffers, flags, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_send"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_send"));
 
     start_op(impl, reactor::write_op, p.p, is_continuation, true,
         ((impl.state_ & socket_ops::stream_oriented)
@@ -231,12 +293,11 @@ class reactive_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_send(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_send(null_buffers)"));
 
     start_op(impl, reactor::write_op, p.p, is_continuation, false, false);
     p.v = p.p = 0;
@@ -260,7 +321,7 @@ class reactive_socket_service_base
       socket_base::message_flags, boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_read(impl.socket_, impl.state_, ec);
+    socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
 
     return 0;
   }
@@ -278,11 +339,11 @@ class reactive_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_socket_recv_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.socket_, impl.state_, buffers, flags, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_receive"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_receive"));
 
     start_op(impl,
         (flags & socket_base::message_out_of_band)
@@ -306,12 +367,11 @@ class reactive_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_receive(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_receive(null_buffers)"));
 
     start_op(impl,
         (flags & socket_base::message_out_of_band)
@@ -341,7 +401,7 @@ class reactive_socket_service_base
       socket_base::message_flags& out_flags, boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_read(impl.socket_, impl.state_, ec);
+    socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
 
     // Clear out_flags, since we cannot give it any other sensible value when
     // performing a null_buffers operation.
@@ -363,12 +423,11 @@ class reactive_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_socket_recvmsg_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.socket_, buffers, in_flags, out_flags, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_receive_with_flags"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_receive_with_flags"));
 
     start_op(impl,
         (in_flags & socket_base::message_out_of_band)
@@ -390,12 +449,11 @@ class reactive_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef reactive_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl,
-          "async_receive_with_flags(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((reactor_.context(), *p.p, "socket",
+          &impl, impl.socket_, "async_receive_with_flags(null_buffers)"));
 
     // Clear out_flags, since we cannot give it any other sensible value when
     // performing a null_buffers operation.
@@ -432,6 +490,9 @@ class reactive_socket_service_base
       reactor_op* op, bool is_continuation,
       const socket_addr_type* addr, size_t addrlen);
 
+  // The io_context that owns this socket service.
+  io_context& io_context_;
+
   // The selector that performs event demultiplexing for the service.
   reactor& reactor_;
 };
diff --git a/include/boost/asio/detail/reactive_wait_op.hpp b/include/boost/asio/detail/reactive_wait_op.hpp
new file mode 100644
index 0000000000..9bc4e2c1c5
--- /dev/null
+++ b/include/boost/asio/detail/reactive_wait_op.hpp
@@ -0,0 +1,92 @@
+//
+// detail/reactive_wait_op.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_REACTIVE_WAIT_OP_HPP
+#define BOOST_ASIO_DETAIL_REACTIVE_WAIT_OP_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/reactor_op.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Handler>
+class reactive_wait_op : public reactor_op
+{
+public:
+  BOOST_ASIO_DEFINE_HANDLER_PTR(reactive_wait_op);
+
+  reactive_wait_op(Handler& handler)
+    : reactor_op(&reactive_wait_op::do_perform,
+        &reactive_wait_op::do_complete),
+      handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
+  {
+    handler_work<Handler>::start(handler_);
+  }
+
+  static status do_perform(reactor_op*)
+  {
+    return done;
+  }
+
+  static void do_complete(void* owner, operation* base,
+      const boost::system::error_code& /*ec*/,
+      std::size_t /*bytes_transferred*/)
+  {
+    // Take ownership of the handler object.
+    reactive_wait_op* o(static_cast<reactive_wait_op*>(base));
+    ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
+
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
+
+    // Make a copy of the handler so that the memory can be deallocated before
+    // the upcall is made. Even if we're not about to make an upcall, a
+    // sub-object of the handler may be the true owner of the memory associated
+    // with the handler. Consequently, a local copy of the handler is required
+    // to ensure that any owning sub-object remains valid until after we have
+    // deallocated the memory here.
+    detail::binder1<Handler, boost::system::error_code>
+      handler(o->handler_, o->ec_);
+    p.h = boost::asio::detail::addressof(handler.handler_);
+    p.reset();
+
+    // Make the upcall if required.
+    if (owner)
+    {
+      fenced_block b(fenced_block::half);
+      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
+      w.complete(handler, handler.handler_);
+      BOOST_ASIO_HANDLER_INVOCATION_END;
+    }
+  }
+
+private:
+  Handler handler_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_REACTIVE_WAIT_OP_HPP
diff --git a/include/boost/asio/detail/reactor.hpp b/include/boost/asio/detail/reactor.hpp
index 1a4ace8776..e65df12863 100644
--- a/include/boost/asio/detail/reactor.hpp
+++ b/include/boost/asio/detail/reactor.hpp
@@ -23,7 +23,7 @@
 # include <boost/asio/detail/kqueue_reactor.hpp>
 #elif defined(BOOST_ASIO_HAS_DEV_POLL)
 # include <boost/asio/detail/dev_poll_reactor.hpp>
-#elif defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#elif defined(BOOST_ASIO_HAS_IOCP) || defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/null_reactor.hpp>
 #else
 # include <boost/asio/detail/select_reactor.hpp>
diff --git a/include/boost/asio/detail/reactor_fwd.hpp b/include/boost/asio/detail/reactor_fwd.hpp
index 6b2e49f5a4..d14ed4cf9c 100644
--- a/include/boost/asio/detail/reactor_fwd.hpp
+++ b/include/boost/asio/detail/reactor_fwd.hpp
@@ -21,7 +21,7 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#if defined(BOOST_ASIO_HAS_IOCP) || defined(BOOST_ASIO_WINDOWS_RUNTIME)
 typedef class null_reactor reactor;
 #elif defined(BOOST_ASIO_HAS_IOCP)
 typedef class select_reactor reactor;
diff --git a/include/boost/asio/detail/reactor_op.hpp b/include/boost/asio/detail/reactor_op.hpp
index c5964dea37..c2540545d5 100644
--- a/include/boost/asio/detail/reactor_op.hpp
+++ b/include/boost/asio/detail/reactor_op.hpp
@@ -34,14 +34,18 @@ class reactor_op
   // The number of bytes transferred, to be passed to the completion handler.
   std::size_t bytes_transferred_;
 
+  // Status returned by perform function. May be used to decide whether it is
+  // worth performing more operations on the descriptor immediately.
+  enum status { not_done, done, done_and_exhausted };
+
   // Perform the operation. Returns true if it is finished.
-  bool perform()
+  status perform()
   {
     return perform_func_(this);
   }
 
 protected:
-  typedef bool (*perform_func_type)(reactor_op*);
+  typedef status (*perform_func_type)(reactor_op*);
 
   reactor_op(perform_func_type perform_func, func_type complete_func)
     : operation(complete_func),
diff --git a/include/boost/asio/detail/recycling_allocator.hpp b/include/boost/asio/detail/recycling_allocator.hpp
new file mode 100644
index 0000000000..050e8bdfa0
--- /dev/null
+++ b/include/boost/asio/detail/recycling_allocator.hpp
@@ -0,0 +1,106 @@
+//
+// detail/recycling_allocator.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_RECYCLING_ALLOCATOR_HPP
+#define BOOST_ASIO_DETAIL_RECYCLING_ALLOCATOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/thread_context.hpp>
+#include <boost/asio/detail/thread_info_base.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T>
+class recycling_allocator
+{
+public:
+  typedef T value_type;
+
+  template <typename U>
+  struct rebind
+  {
+    typedef recycling_allocator<U> other;
+  };
+
+  recycling_allocator()
+  {
+  }
+
+  template <typename U>
+  recycling_allocator(const recycling_allocator<U>&)
+  {
+  }
+
+  T* allocate(std::size_t n)
+  {
+    typedef thread_context::thread_call_stack call_stack;
+    void* p = thread_info_base::allocate(call_stack::top(), sizeof(T) * n);
+    return static_cast<T*>(p);
+  }
+
+  void deallocate(T* p, std::size_t n)
+  {
+    typedef thread_context::thread_call_stack call_stack;
+    thread_info_base::deallocate(call_stack::top(), p, sizeof(T) * n);
+  }
+};
+
+template <>
+class recycling_allocator<void>
+{
+public:
+  typedef void value_type;
+
+  template <typename U>
+  struct rebind
+  {
+    typedef recycling_allocator<U> other;
+  };
+
+  recycling_allocator()
+  {
+  }
+
+  template <typename U>
+  recycling_allocator(const recycling_allocator<U>&)
+  {
+  }
+};
+
+template <typename Allocator>
+struct get_recycling_allocator
+{
+  typedef Allocator type;
+  static type get(const Allocator& a) { return a; }
+};
+
+template <typename T>
+struct get_recycling_allocator<std::allocator<T> >
+{
+  typedef recycling_allocator<T> type;
+  static type get(const std::allocator<T>&) { return type(); }
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_RECYCLING_ALLOCATOR_HPP
diff --git a/include/boost/asio/detail/resolve_endpoint_op.hpp b/include/boost/asio/detail/resolve_endpoint_op.hpp
index 0b7060ad6b..4a2c06798a 100644
--- a/include/boost/asio/detail/resolve_endpoint_op.hpp
+++ b/include/boost/asio/detail/resolve_endpoint_op.hpp
@@ -17,14 +17,14 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ip/basic_resolver_iterator.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/ip/basic_resolver_results.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
-#include <boost/asio/detail/operation.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/resolve_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -34,35 +34,37 @@ namespace asio {
 namespace detail {
 
 template <typename Protocol, typename Handler>
-class resolve_endpoint_op : public operation
+class resolve_endpoint_op : public resolve_op
 {
 public:
   BOOST_ASIO_DEFINE_HANDLER_PTR(resolve_endpoint_op);
 
   typedef typename Protocol::endpoint endpoint_type;
-  typedef boost::asio::ip::basic_resolver_iterator<Protocol> iterator_type;
+  typedef boost::asio::ip::basic_resolver_results<Protocol> results_type;
 
   resolve_endpoint_op(socket_ops::weak_cancel_token_type cancel_token,
-      const endpoint_type& endpoint, io_service_impl& ios, Handler& handler)
-    : operation(&resolve_endpoint_op::do_complete),
+      const endpoint_type& endpoint, io_context_impl& ioc, Handler& handler)
+    : resolve_op(&resolve_endpoint_op::do_complete),
       cancel_token_(cancel_token),
       endpoint_(endpoint),
-      io_service_impl_(ios),
+      io_context_impl_(ioc),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the operation object.
     resolve_endpoint_op* o(static_cast<resolve_endpoint_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    if (owner && owner != &o->io_service_impl_)
+    if (owner && owner != &o->io_context_impl_)
     {
-      // The operation is being run on the worker io_service. Time to perform
+      // The operation is being run on the worker io_context. Time to perform
       // the resolver operation.
     
       // Perform the blocking endpoint resolution operation.
@@ -71,18 +73,18 @@ class resolve_endpoint_op : public operation
       socket_ops::background_getnameinfo(o->cancel_token_, o->endpoint_.data(),
           o->endpoint_.size(), host_name, NI_MAXHOST, service_name, NI_MAXSERV,
           o->endpoint_.protocol().type(), o->ec_);
-      o->iter_ = iterator_type::create(o->endpoint_, host_name, service_name);
+      o->results_ = results_type::create(o->endpoint_, host_name, service_name);
 
-      // Pass operation back to main io_service for completion.
-      o->io_service_impl_.post_deferred_completion(o);
+      // Pass operation back to main io_context for completion.
+      o->io_context_impl_.post_deferred_completion(o);
       p.v = p.p = 0;
     }
     else
     {
-      // The operation has been returned to the main io_service. The completion
+      // The operation has been returned to the main io_context. The completion
       // handler is ready to be delivered.
 
-      BOOST_ASIO_HANDLER_COMPLETION((o));
+      BOOST_ASIO_HANDLER_COMPLETION((*o));
 
       // Make a copy of the handler so that the memory can be deallocated
       // before the upcall is made. Even if we're not about to make an upcall,
@@ -90,8 +92,8 @@ class resolve_endpoint_op : public operation
       // associated with the handler. Consequently, a local copy of the handler
       // is required to ensure that any owning sub-object remains valid until
       // after we have deallocated the memory here.
-      detail::binder2<Handler, boost::system::error_code, iterator_type>
-        handler(o->handler_, o->ec_, o->iter_);
+      detail::binder2<Handler, boost::system::error_code, results_type>
+        handler(o->handler_, o->ec_, o->results_);
       p.h = boost::asio::detail::addressof(handler.handler_);
       p.reset();
 
@@ -99,7 +101,7 @@ class resolve_endpoint_op : public operation
       {
         fenced_block b(fenced_block::half);
         BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
-        boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+        w.complete(handler, handler.handler_);
         BOOST_ASIO_HANDLER_INVOCATION_END;
       }
     }
@@ -108,10 +110,9 @@ class resolve_endpoint_op : public operation
 private:
   socket_ops::weak_cancel_token_type cancel_token_;
   endpoint_type endpoint_;
-  io_service_impl& io_service_impl_;
+  io_context_impl& io_context_impl_;
   Handler handler_;
-  boost::system::error_code ec_;
-  iterator_type iter_;
+  results_type results_;
 };
 
 } // namespace detail
diff --git a/include/boost/asio/detail/resolve_op.hpp b/include/boost/asio/detail/resolve_op.hpp
index 435e27026f..99f9772f97 100644
--- a/include/boost/asio/detail/resolve_op.hpp
+++ b/include/boost/asio/detail/resolve_op.hpp
@@ -17,16 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ip/basic_resolver_iterator.hpp>
-#include <boost/asio/ip/basic_resolver_query.hpp>
-#include <boost/asio/detail/addressof.hpp>
-#include <boost/asio/detail/bind_handler.hpp>
-#include <boost/asio/detail/fenced_block.hpp>
-#include <boost/asio/detail/handler_alloc_helpers.hpp>
-#include <boost/asio/detail/handler_invoke_helpers.hpp>
 #include <boost/asio/detail/operation.hpp>
-#include <boost/asio/detail/socket_ops.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -34,94 +25,17 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-template <typename Protocol, typename Handler>
 class resolve_op : public operation
 {
 public:
-  BOOST_ASIO_DEFINE_HANDLER_PTR(resolve_op);
-
-  typedef boost::asio::ip::basic_resolver_query<Protocol> query_type;
-  typedef boost::asio::ip::basic_resolver_iterator<Protocol> iterator_type;
-
-  resolve_op(socket_ops::weak_cancel_token_type cancel_token,
-      const query_type& query, io_service_impl& ios, Handler& handler)
-    : operation(&resolve_op::do_complete),
-      cancel_token_(cancel_token),
-      query_(query),
-      io_service_impl_(ios),
-      handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
-      addrinfo_(0)
-  {
-  }
+  // The error code to be passed to the completion handler.
+  boost::system::error_code ec_;
 
-  ~resolve_op()
+protected:
+  resolve_op(func_type complete_func)
+    : operation(complete_func)
   {
-    if (addrinfo_)
-      socket_ops::freeaddrinfo(addrinfo_);
   }
-
-  static void do_complete(io_service_impl* owner, operation* base,
-      const boost::system::error_code& /*ec*/,
-      std::size_t /*bytes_transferred*/)
-  {
-    // Take ownership of the operation object.
-    resolve_op* o(static_cast<resolve_op*>(base));
-    ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
-
-    if (owner && owner != &o->io_service_impl_)
-    {
-      // The operation is being run on the worker io_service. Time to perform
-      // the resolver operation.
-    
-      // Perform the blocking host resolution operation.
-      socket_ops::background_getaddrinfo(o->cancel_token_,
-          o->query_.host_name().c_str(), o->query_.service_name().c_str(),
-          o->query_.hints(), &o->addrinfo_, o->ec_);
-
-      // Pass operation back to main io_service for completion.
-      o->io_service_impl_.post_deferred_completion(o);
-      p.v = p.p = 0;
-    }
-    else
-    {
-      // The operation has been returned to the main io_service. The completion
-      // handler is ready to be delivered.
-
-      BOOST_ASIO_HANDLER_COMPLETION((o));
-
-      // Make a copy of the handler so that the memory can be deallocated
-      // before the upcall is made. Even if we're not about to make an upcall,
-      // a sub-object of the handler may be the true owner of the memory
-      // associated with the handler. Consequently, a local copy of the handler
-      // is required to ensure that any owning sub-object remains valid until
-      // after we have deallocated the memory here.
-      detail::binder2<Handler, boost::system::error_code, iterator_type>
-        handler(o->handler_, o->ec_, iterator_type());
-      p.h = boost::asio::detail::addressof(handler.handler_);
-      if (o->addrinfo_)
-      {
-        handler.arg2_ = iterator_type::create(o->addrinfo_,
-            o->query_.host_name(), o->query_.service_name());
-      }
-      p.reset();
-
-      if (owner)
-      {
-        fenced_block b(fenced_block::half);
-        BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
-        boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
-        BOOST_ASIO_HANDLER_INVOCATION_END;
-      }
-    }
-  }
-
-private:
-  socket_ops::weak_cancel_token_type cancel_token_;
-  query_type query_;
-  io_service_impl& io_service_impl_;
-  Handler handler_;
-  boost::system::error_code ec_;
-  boost::asio::detail::addrinfo_type* addrinfo_;
 };
 
 } // namespace detail
diff --git a/include/boost/asio/detail/resolve_query_op.hpp b/include/boost/asio/detail/resolve_query_op.hpp
new file mode 100644
index 0000000000..6e5c431941
--- /dev/null
+++ b/include/boost/asio/detail/resolve_query_op.hpp
@@ -0,0 +1,136 @@
+//
+// detail/resolve_query_op.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_RESOLVE_QUERY_OP_HPP
+#define BOOST_ASIO_DETAIL_RESOLVE_QUERY_OP_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/ip/basic_resolver_query.hpp>
+#include <boost/asio/ip/basic_resolver_results.hpp>
+#include <boost/asio/detail/bind_handler.hpp>
+#include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/resolve_op.hpp>
+#include <boost/asio/detail/socket_ops.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Protocol, typename Handler>
+class resolve_query_op : public resolve_op
+{
+public:
+  BOOST_ASIO_DEFINE_HANDLER_PTR(resolve_query_op);
+
+  typedef boost::asio::ip::basic_resolver_query<Protocol> query_type;
+  typedef boost::asio::ip::basic_resolver_results<Protocol> results_type;
+
+  resolve_query_op(socket_ops::weak_cancel_token_type cancel_token,
+      const query_type& query, io_context_impl& ioc, Handler& handler)
+    : resolve_op(&resolve_query_op::do_complete),
+      cancel_token_(cancel_token),
+      query_(query),
+      io_context_impl_(ioc),
+      handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
+      addrinfo_(0)
+  {
+    handler_work<Handler>::start(handler_);
+  }
+
+  ~resolve_query_op()
+  {
+    if (addrinfo_)
+      socket_ops::freeaddrinfo(addrinfo_);
+  }
+
+  static void do_complete(void* owner, operation* base,
+      const boost::system::error_code& /*ec*/,
+      std::size_t /*bytes_transferred*/)
+  {
+    // Take ownership of the operation object.
+    resolve_query_op* o(static_cast<resolve_query_op*>(base));
+    ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+
+    if (owner && owner != &o->io_context_impl_)
+    {
+      // The operation is being run on the worker io_context. Time to perform
+      // the resolver operation.
+    
+      // Perform the blocking host resolution operation.
+      socket_ops::background_getaddrinfo(o->cancel_token_,
+          o->query_.host_name().c_str(), o->query_.service_name().c_str(),
+          o->query_.hints(), &o->addrinfo_, o->ec_);
+
+      // Pass operation back to main io_context for completion.
+      o->io_context_impl_.post_deferred_completion(o);
+      p.v = p.p = 0;
+    }
+    else
+    {
+      // The operation has been returned to the main io_context. The completion
+      // handler is ready to be delivered.
+
+      // Take ownership of the operation's outstanding work.
+      handler_work<Handler> w(o->handler_);
+
+      BOOST_ASIO_HANDLER_COMPLETION((*o));
+
+      // Make a copy of the handler so that the memory can be deallocated
+      // before the upcall is made. Even if we're not about to make an upcall,
+      // a sub-object of the handler may be the true owner of the memory
+      // associated with the handler. Consequently, a local copy of the handler
+      // is required to ensure that any owning sub-object remains valid until
+      // after we have deallocated the memory here.
+      detail::binder2<Handler, boost::system::error_code, results_type>
+        handler(o->handler_, o->ec_, results_type());
+      p.h = boost::asio::detail::addressof(handler.handler_);
+      if (o->addrinfo_)
+      {
+        handler.arg2_ = results_type::create(o->addrinfo_,
+            o->query_.host_name(), o->query_.service_name());
+      }
+      p.reset();
+
+      if (owner)
+      {
+        fenced_block b(fenced_block::half);
+        BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
+        w.complete(handler, handler.handler_);
+        BOOST_ASIO_HANDLER_INVOCATION_END;
+      }
+    }
+  }
+
+private:
+  socket_ops::weak_cancel_token_type cancel_token_;
+  query_type query_;
+  io_context_impl& io_context_impl_;
+  Handler handler_;
+  boost::asio::detail::addrinfo_type* addrinfo_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_RESOLVE_QUERY_OP_HPP
diff --git a/include/boost/asio/detail/resolver_service.hpp b/include/boost/asio/detail/resolver_service.hpp
index f73742e9b0..bda1139eb7 100644
--- a/include/boost/asio/detail/resolver_service.hpp
+++ b/include/boost/asio/detail/resolver_service.hpp
@@ -19,11 +19,12 @@
 
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-#include <boost/asio/ip/basic_resolver_iterator.hpp>
 #include <boost/asio/ip/basic_resolver_query.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/ip/basic_resolver_results.hpp>
+#include <boost/asio/detail/concurrency_hint.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/resolve_endpoint_op.hpp>
-#include <boost/asio/detail/resolve_op.hpp>
+#include <boost/asio/detail/resolve_query_op.hpp>
 #include <boost/asio/detail/resolver_service_base.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -33,7 +34,9 @@ namespace asio {
 namespace detail {
 
 template <typename Protocol>
-class resolver_service : public resolver_service_base
+class resolver_service :
+  public service_base<resolver_service<Protocol> >,
+  public resolver_service_base
 {
 public:
   // The implementation type of the resolver. A cancellation token is used to
@@ -46,17 +49,30 @@ class resolver_service : public resolver_service_base
   // The query type.
   typedef boost::asio::ip::basic_resolver_query<Protocol> query_type;
 
-  // The iterator type.
-  typedef boost::asio::ip::basic_resolver_iterator<Protocol> iterator_type;
+  // The results type.
+  typedef boost::asio::ip::basic_resolver_results<Protocol> results_type;
 
   // Constructor.
-  resolver_service(boost::asio::io_service& io_service)
-    : resolver_service_base(io_service)
+  resolver_service(boost::asio::io_context& io_context)
+    : service_base<resolver_service<Protocol> >(io_context),
+      resolver_service_base(io_context)
   {
   }
 
+  // Destroy all user-defined handler objects owned by the service.
+  void shutdown()
+  {
+    this->base_shutdown();
+  }
+
+  // Perform any fork-related housekeeping.
+  void notify_fork(boost::asio::io_context::fork_event fork_ev)
+  {
+    this->base_notify_fork(fork_ev);
+  }
+
   // Resolve a query to a list of entries.
-  iterator_type resolve(implementation_type&, const query_type& query,
+  results_type resolve(implementation_type&, const query_type& query,
       boost::system::error_code& ec)
   {
     boost::asio::detail::addrinfo_type* address_info = 0;
@@ -65,7 +81,7 @@ class resolver_service : public resolver_service_base
         query.service_name().c_str(), query.hints(), &address_info, ec);
     auto_addrinfo auto_address_info(address_info);
 
-    return ec ? iterator_type() : iterator_type::create(
+    return ec ? results_type() : results_type::create(
         address_info, query.host_name(), query.service_name());
   }
 
@@ -75,20 +91,20 @@ class resolver_service : public resolver_service_base
       const query_type& query, Handler& handler)
   {
     // Allocate and construct an operation to wrap the handler.
-    typedef resolve_op<Protocol, Handler> op;
+    typedef resolve_query_op<Protocol, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
-    p.p = new (p.v) op(impl, query, io_service_impl_, handler);
+      op::ptr::allocate(handler), 0 };
+    p.p = new (p.v) op(impl, query, io_context_impl_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "resolver", &impl, "async_resolve"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_impl_.context(),
+          *p.p, "resolver", &impl, 0, "async_resolve"));
 
     start_resolve_op(p.p);
     p.v = p.p = 0;
   }
 
   // Resolve an endpoint to a list of entries.
-  iterator_type resolve(implementation_type&,
+  results_type resolve(implementation_type&,
       const endpoint_type& endpoint, boost::system::error_code& ec)
   {
     char host_name[NI_MAXHOST];
@@ -97,7 +113,7 @@ class resolver_service : public resolver_service_base
         host_name, NI_MAXHOST, service_name, NI_MAXSERV,
         endpoint.protocol().type(), ec);
 
-    return ec ? iterator_type() : iterator_type::create(
+    return ec ? results_type() : results_type::create(
         endpoint, host_name, service_name);
   }
 
@@ -109,11 +125,11 @@ class resolver_service : public resolver_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef resolve_endpoint_op<Protocol, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
-    p.p = new (p.v) op(impl, endpoint, io_service_impl_, handler);
+      op::ptr::allocate(handler), 0 };
+    p.p = new (p.v) op(impl, endpoint, io_context_impl_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "resolver", &impl, "async_resolve"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_impl_.context(),
+          *p.p, "resolver", &impl, 0, "async_resolve"));
 
     start_resolve_op(p.p);
     p.v = p.p = 0;
diff --git a/include/boost/asio/detail/resolver_service_base.hpp b/include/boost/asio/detail/resolver_service_base.hpp
index 1a4180c166..818e20b02b 100644
--- a/include/boost/asio/detail/resolver_service_base.hpp
+++ b/include/boost/asio/detail/resolver_service_base.hpp
@@ -17,10 +17,11 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/executor_work_guard.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
-#include <boost/asio/detail/operation.hpp>
+#include <boost/asio/detail/resolve_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/detail/socket_types.hpp>
 #include <boost/asio/detail/scoped_ptr.hpp>
@@ -40,17 +41,17 @@ class resolver_service_base
   typedef socket_ops::shared_cancel_token_type implementation_type;
 
   // Constructor.
-  BOOST_ASIO_DECL resolver_service_base(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL resolver_service_base(boost::asio::io_context& io_context);
 
   // Destructor.
   BOOST_ASIO_DECL ~resolver_service_base();
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void base_shutdown();
 
   // Perform any fork-related housekeeping.
-  BOOST_ASIO_DECL void fork_service(
-      boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void base_notify_fork(
+      boost::asio::io_context::fork_event fork_ev);
 
   // Construct a new resolver implementation.
   BOOST_ASIO_DECL void construct(implementation_type& impl);
@@ -58,12 +59,21 @@ class resolver_service_base
   // Destroy a resolver implementation.
   BOOST_ASIO_DECL void destroy(implementation_type&);
 
+  // Move-construct a new resolver implementation.
+  BOOST_ASIO_DECL void move_construct(implementation_type& impl,
+      implementation_type& other_impl);
+
+  // Move-assign from another resolver implementation.
+  BOOST_ASIO_DECL void move_assign(implementation_type& impl,
+      resolver_service_base& other_service,
+      implementation_type& other_impl);
+
   // Cancel pending asynchronous operations.
   BOOST_ASIO_DECL void cancel(implementation_type& impl);
 
 protected:
   // Helper function to start an asynchronous resolve operation.
-  BOOST_ASIO_DECL void start_resolve_op(operation* op);
+  BOOST_ASIO_DECL void start_resolve_op(resolve_op* op);
 
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
   // Helper class to perform exception-safe cleanup of addrinfo objects.
@@ -92,29 +102,30 @@ class resolver_service_base
   };
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-  // Helper class to run the work io_service in a thread.
-  class work_io_service_runner;
+  // Helper class to run the work io_context in a thread.
+  class work_io_context_runner;
 
   // Start the work thread if it's not already running.
   BOOST_ASIO_DECL void start_work_thread();
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_impl_;
+  // The io_context implementation used to post completions.
+  io_context_impl& io_context_impl_;
 
 private:
   // Mutex to protect access to internal data.
   boost::asio::detail::mutex mutex_;
 
-  // Private io_service used for performing asynchronous host resolution.
-  boost::asio::detail::scoped_ptr<boost::asio::io_service> work_io_service_;
+  // Private io_context used for performing asynchronous host resolution.
+  boost::asio::detail::scoped_ptr<boost::asio::io_context> work_io_context_;
 
-  // The work io_service implementation used to post completions.
-  io_service_impl& work_io_service_impl_;
+  // The work io_context implementation used to post completions.
+  io_context_impl& work_io_context_impl_;
 
-  // Work for the private io_service to perform.
-  boost::asio::detail::scoped_ptr<boost::asio::io_service::work> work_;
+  // Work for the private io_context to perform.
+  boost::asio::executor_work_guard<
+      boost::asio::io_context::executor_type> work_;
 
-  // Thread used for running the work io_service's run loop.
+  // Thread used for running the work io_context's run loop.
   boost::asio::detail::scoped_ptr<boost::asio::detail::thread> work_thread_;
 };
 
diff --git a/include/boost/asio/detail/task_io_service.hpp b/include/boost/asio/detail/scheduler.hpp
similarity index 68%
rename from include/boost/asio/detail/task_io_service.hpp
rename to include/boost/asio/detail/scheduler.hpp
index 5184ea5a58..1d64a062c8 100644
--- a/include/boost/asio/detail/task_io_service.hpp
+++ b/include/boost/asio/detail/scheduler.hpp
@@ -1,6 +1,6 @@
 //
-// detail/task_io_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+// detail/scheduler.hpp
+// ~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
-#define BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
+#ifndef BOOST_ASIO_DETAIL_SCHEDULER_HPP
+#define BOOST_ASIO_DETAIL_SCHEDULER_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -17,17 +17,15 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_HAS_IOCP)
-
 #include <boost/system/error_code.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/execution_context.hpp>
 #include <boost/asio/detail/atomic_count.hpp>
-#include <boost/asio/detail/call_stack.hpp>
-#include <boost/asio/detail/event.hpp>
-#include <boost/asio/detail/mutex.hpp>
+#include <boost/asio/detail/conditionally_enabled_event.hpp>
+#include <boost/asio/detail/conditionally_enabled_mutex.hpp>
 #include <boost/asio/detail/op_queue.hpp>
 #include <boost/asio/detail/reactor_fwd.hpp>
-#include <boost/asio/detail/task_io_service_operation.hpp>
+#include <boost/asio/detail/scheduler_operation.hpp>
+#include <boost/asio/detail/thread_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -35,21 +33,22 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-struct task_io_service_thread_info;
+struct scheduler_thread_info;
 
-class task_io_service
-  : public boost::asio::detail::service_base<task_io_service>
+class scheduler
+  : public execution_context_service_base<scheduler>,
+    public thread_context
 {
 public:
-  typedef task_io_service_operation operation;
+  typedef scheduler_operation operation;
 
   // Constructor. Specifies the number of concurrent threads that are likely to
-  // run the io_service. If set to 1 certain optimisation are performed.
-  BOOST_ASIO_DECL task_io_service(boost::asio::io_service& io_service,
-      std::size_t concurrency_hint = 0);
+  // run the scheduler. If set to 1 certain optimisation are performed.
+  BOOST_ASIO_DECL scheduler(boost::asio::execution_context& ctx,
+      int concurrency_hint = 0);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Initialise the task, if required.
   BOOST_ASIO_DECL void init_task();
@@ -60,6 +59,10 @@ class task_io_service
   // Run until interrupted or one operation is performed.
   BOOST_ASIO_DECL std::size_t run_one(boost::system::error_code& ec);
 
+  // Run until timeout, interrupted, or one operation is performed.
+  BOOST_ASIO_DECL std::size_t wait_one(
+      long usec, boost::system::error_code& ec);
+
   // Poll for operations without blocking.
   BOOST_ASIO_DECL std::size_t poll(boost::system::error_code& ec);
 
@@ -69,11 +72,11 @@ class task_io_service
   // Interrupt the event processing loop.
   BOOST_ASIO_DECL void stop();
 
-  // Determine whether the io_service is stopped.
+  // Determine whether the scheduler is stopped.
   BOOST_ASIO_DECL bool stopped() const;
 
-  // Reset in preparation for a subsequent run invocation.
-  BOOST_ASIO_DECL void reset();
+  // Restart in preparation for a subsequent run invocation.
+  BOOST_ASIO_DECL void restart();
 
   // Notify that some work has started.
   void work_started()
@@ -81,6 +84,10 @@ class task_io_service
     ++outstanding_work_;
   }
 
+  // Used to compensate for a forthcoming work_finished call. Must be called
+  // from within a scheduler-owned thread.
+  BOOST_ASIO_DECL void compensating_work_started();
+
   // Notify that some work has finished.
   void work_finished()
   {
@@ -94,14 +101,6 @@ class task_io_service
     return thread_call_stack::contains(this) != 0;
   }
 
-  // Request invocation of the given handler.
-  template <typename Handler>
-  void dispatch(Handler& handler);
-
-  // Request invocation of the given handler and return immediately.
-  template <typename Handler>
-  void post(Handler& handler);
-
   // Request invocation of the given operation and return immediately. Assumes
   // that work_started() has not yet been called for the operation.
   BOOST_ASIO_DECL void post_immediate_completion(
@@ -115,22 +114,38 @@ class task_io_service
   // that work_started() was previously called for each operation.
   BOOST_ASIO_DECL void post_deferred_completions(op_queue<operation>& ops);
 
-  // Process unfinished operations as part of a shutdown_service operation.
-  // Assumes that work_started() was previously called for the operations.
+  // Enqueue the given operation following a failed attempt to dispatch the
+  // operation for immediate invocation.
+  BOOST_ASIO_DECL void do_dispatch(operation* op);
+
+  // Process unfinished operations as part of a shutdownoperation. Assumes that
+  // work_started() was previously called for the operations.
   BOOST_ASIO_DECL void abandon_operations(op_queue<operation>& ops);
 
+  // Get the concurrency hint that was used to initialise the scheduler.
+  int concurrency_hint() const
+  {
+    return concurrency_hint_;
+  }
+
 private:
-  // Structure containing thread-specific data.
-  typedef task_io_service_thread_info thread_info;
+  // The mutex type used by this scheduler.
+  typedef conditionally_enabled_mutex mutex;
 
-  // Enqueue the given operation following a failed attempt to dispatch the
-  // operation for immediate invocation.
-  BOOST_ASIO_DECL void do_dispatch(operation* op);
+  // The event type used by this scheduler.
+  typedef conditionally_enabled_event event;
+
+  // Structure containing thread-specific data.
+  typedef scheduler_thread_info thread_info;
 
   // Run at most one operation. May block.
   BOOST_ASIO_DECL std::size_t do_run_one(mutex::scoped_lock& lock,
       thread_info& this_thread, const boost::system::error_code& ec);
 
+  // Run at most one operation with a timeout. May block.
+  BOOST_ASIO_DECL std::size_t do_wait_one(mutex::scoped_lock& lock,
+      thread_info& this_thread, long usec, const boost::system::error_code& ec);
+
   // Poll for at most one operation.
   BOOST_ASIO_DECL std::size_t do_poll_one(mutex::scoped_lock& lock,
       thread_info& this_thread, const boost::system::error_code& ec);
@@ -183,8 +198,8 @@ class task_io_service
   // Flag to indicate that the dispatcher has been shut down.
   bool shutdown_;
 
-  // Per-thread call stack to track the state of each thread in the io_service.
-  typedef call_stack<task_io_service, thread_info> thread_call_stack;
+  // The concurrency hint used to initialise the scheduler.
+  const int concurrency_hint_;
 };
 
 } // namespace detail
@@ -193,11 +208,8 @@ class task_io_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#include <boost/asio/detail/impl/task_io_service.hpp>
 #if defined(BOOST_ASIO_HEADER_ONLY)
-# include <boost/asio/detail/impl/task_io_service.ipp>
+# include <boost/asio/detail/impl/scheduler.ipp>
 #endif // defined(BOOST_ASIO_HEADER_ONLY)
 
-#endif // !defined(BOOST_ASIO_HAS_IOCP)
-
-#endif // BOOST_ASIO_DETAIL_TASK_IO_SERVICE_HPP
+#endif // BOOST_ASIO_DETAIL_SCHEDULER_HPP
diff --git a/include/boost/asio/detail/task_io_service_operation.hpp b/include/boost/asio/detail/scheduler_operation.hpp
similarity index 63%
rename from include/boost/asio/detail/task_io_service_operation.hpp
rename to include/boost/asio/detail/scheduler_operation.hpp
index 91bee25cb4..54a8a7a206 100644
--- a/include/boost/asio/detail/task_io_service_operation.hpp
+++ b/include/boost/asio/detail/scheduler_operation.hpp
@@ -1,6 +1,6 @@
 //
-// detail/task_io_service_operation.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// detail/scheduler_operation.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_TASK_IO_SERVICE_OPERATION_HPP
-#define BOOST_ASIO_DETAIL_TASK_IO_SERVICE_OPERATION_HPP
+#ifndef BOOST_ASIO_DETAIL_SCHEDULER_OPERATION_HPP
+#define BOOST_ASIO_DETAIL_SCHEDULER_OPERATION_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -25,17 +25,19 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-class task_io_service;
+class scheduler;
 
 // Base class for all operations. A function pointer is used instead of virtual
 // functions to avoid the associated overhead.
-class task_io_service_operation BOOST_ASIO_INHERIT_TRACKED_HANDLER
+class scheduler_operation BOOST_ASIO_INHERIT_TRACKED_HANDLER
 {
 public:
-  void complete(task_io_service& owner,
-      const boost::system::error_code& ec, std::size_t bytes_transferred)
+  typedef scheduler_operation operation_type;
+
+  void complete(void* owner, const boost::system::error_code& ec,
+      std::size_t bytes_transferred)
   {
-    func_(&owner, this, ec, bytes_transferred);
+    func_(owner, this, ec, bytes_transferred);
   }
 
   void destroy()
@@ -44,11 +46,11 @@ class task_io_service_operation BOOST_ASIO_INHERIT_TRACKED_HANDLER
   }
 
 protected:
-  typedef void (*func_type)(task_io_service*,
-      task_io_service_operation*,
+  typedef void (*func_type)(void*,
+      scheduler_operation*,
       const boost::system::error_code&, std::size_t);
 
-  task_io_service_operation(func_type func)
+  scheduler_operation(func_type func)
     : next_(0),
       func_(func),
       task_result_(0)
@@ -56,16 +58,16 @@ class task_io_service_operation BOOST_ASIO_INHERIT_TRACKED_HANDLER
   }
 
   // Prevents deletion through this type.
-  ~task_io_service_operation()
+  ~scheduler_operation()
   {
   }
 
 private:
   friend class op_queue_access;
-  task_io_service_operation* next_;
+  scheduler_operation* next_;
   func_type func_;
 protected:
-  friend class task_io_service;
+  friend class scheduler;
   unsigned int task_result_; // Passed into bytes transferred.
 };
 
@@ -75,4 +77,4 @@ class task_io_service_operation BOOST_ASIO_INHERIT_TRACKED_HANDLER
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#endif // BOOST_ASIO_DETAIL_TASK_IO_SERVICE_OPERATION_HPP
+#endif // BOOST_ASIO_DETAIL_SCHEDULER_OPERATION_HPP
diff --git a/include/boost/asio/detail/task_io_service_thread_info.hpp b/include/boost/asio/detail/scheduler_thread_info.hpp
similarity index 61%
rename from include/boost/asio/detail/task_io_service_thread_info.hpp
rename to include/boost/asio/detail/scheduler_thread_info.hpp
index 0af044c009..79d64783c2 100644
--- a/include/boost/asio/detail/task_io_service_thread_info.hpp
+++ b/include/boost/asio/detail/scheduler_thread_info.hpp
@@ -1,6 +1,6 @@
 //
-// detail/task_io_service_thread_info.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// detail/scheduler_thread_info.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_TASK_IO_SERVICE_THREAD_INFO_HPP
-#define BOOST_ASIO_DETAIL_TASK_IO_SERVICE_THREAD_INFO_HPP
+#ifndef BOOST_ASIO_DETAIL_SCHEDULER_THREAD_INFO_HPP
+#define BOOST_ASIO_DETAIL_SCHEDULER_THREAD_INFO_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -24,12 +24,12 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-class task_io_service;
-class task_io_service_operation;
+class scheduler;
+class scheduler_operation;
 
-struct task_io_service_thread_info : public thread_info_base
+struct scheduler_thread_info : public thread_info_base
 {
-  op_queue<task_io_service_operation> private_op_queue;
+  op_queue<scheduler_operation> private_op_queue;
   long private_outstanding_work;
 };
 
@@ -39,4 +39,4 @@ struct task_io_service_thread_info : public thread_info_base
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#endif // BOOST_ASIO_DETAIL_TASK_IO_SERVICE_THREAD_INFO_HPP
+#endif // BOOST_ASIO_DETAIL_SCHEDULER_THREAD_INFO_HPP
diff --git a/include/boost/asio/detail/scoped_ptr.hpp b/include/boost/asio/detail/scoped_ptr.hpp
index fd471631e1..80ced171cd 100644
--- a/include/boost/asio/detail/scoped_ptr.hpp
+++ b/include/boost/asio/detail/scoped_ptr.hpp
@@ -64,6 +64,14 @@ class scoped_ptr
     p_ = p;
   }
 
+  // Release ownership of the pointer.
+  T* release()
+  {
+    T* tmp = p_;
+    p_ = 0;
+    return tmp;
+  }
+
 private:
   // Disallow copying and assignment.
   scoped_ptr(const scoped_ptr&);
diff --git a/include/boost/asio/detail/select_reactor.hpp b/include/boost/asio/detail/select_reactor.hpp
index d6f75242e5..030c092250 100644
--- a/include/boost/asio/detail/select_reactor.hpp
+++ b/include/boost/asio/detail/select_reactor.hpp
@@ -35,7 +35,7 @@
 #include <boost/asio/detail/timer_queue_base.hpp>
 #include <boost/asio/detail/timer_queue_set.hpp>
 #include <boost/asio/detail/wait_op.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/execution_context.hpp>
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 # include <boost/asio/detail/thread.hpp>
@@ -48,7 +48,7 @@ namespace asio {
 namespace detail {
 
 class select_reactor
-  : public boost::asio::detail::service_base<select_reactor>
+  : public execution_context_service_base<select_reactor>
 {
 public:
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -65,17 +65,17 @@ class select_reactor
   };
 
   // Constructor.
-  BOOST_ASIO_DECL select_reactor(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL select_reactor(boost::asio::execution_context& ctx);
 
   // Destructor.
   BOOST_ASIO_DECL ~select_reactor();
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Recreate internal descriptors following a fork.
-  BOOST_ASIO_DECL void fork_service(
-      boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void notify_fork(
+      boost::asio::execution_context::fork_event fork_ev);
 
   // Initialise the task, but only if the reactor is not in its own thread.
   BOOST_ASIO_DECL void init_task();
@@ -93,7 +93,7 @@ class select_reactor
   // Post a reactor operation for immediate completion.
   void post_immediate_completion(reactor_op* op, bool is_continuation)
   {
-    io_service_.post_immediate_completion(op, is_continuation);
+    scheduler_.post_immediate_completion(op, is_continuation);
   }
 
   // Start a new operation. The reactor operation will be performed when the
@@ -149,8 +149,14 @@ class select_reactor
       typename timer_queue<Time_Traits>::per_timer_data& timer,
       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
 
+  // Move the timer operations associated with the given timer.
+  template <typename Time_Traits>
+  void move_timer(timer_queue<Time_Traits>& queue,
+      typename timer_queue<Time_Traits>::per_timer_data& target,
+      typename timer_queue<Time_Traits>::per_timer_data& source);
+
   // Run select once until interrupted or events are ready to be dispatched.
-  BOOST_ASIO_DECL void run(bool block, op_queue<operation>& ops);
+  BOOST_ASIO_DECL void run(long usec, op_queue<operation>& ops);
 
   // Interrupt the select loop.
   BOOST_ASIO_DECL void interrupt();
@@ -159,9 +165,6 @@ class select_reactor
 #if defined(BOOST_ASIO_HAS_IOCP)
   // Run the select loop in the thread.
   BOOST_ASIO_DECL void run_thread();
-
-  // Entry point for the select loop thread.
-  BOOST_ASIO_DECL static void call_run_thread(select_reactor* reactor);
 #endif // defined(BOOST_ASIO_HAS_IOCP)
 
   // Helper function to add a new timer queue.
@@ -171,15 +174,20 @@ class select_reactor
   BOOST_ASIO_DECL void do_remove_timer_queue(timer_queue_base& queue);
 
   // Get the timeout value for the select call.
-  BOOST_ASIO_DECL timeval* get_timeout(timeval& tv);
+  BOOST_ASIO_DECL timeval* get_timeout(long usec, timeval& tv);
 
   // Cancel all operations associated with the given descriptor. This function
   // does not acquire the select_reactor's mutex.
   BOOST_ASIO_DECL void cancel_ops_unlocked(socket_type descriptor,
       const boost::system::error_code& ec);
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_;
+  // The scheduler implementation used to post completions.
+# if defined(BOOST_ASIO_HAS_IOCP)
+  typedef class win_iocp_io_context scheduler_type;
+# else // defined(BOOST_ASIO_HAS_IOCP)
+  typedef class scheduler scheduler_type;
+# endif // defined(BOOST_ASIO_HAS_IOCP)
+  scheduler_type& scheduler_;
 
   // Mutex to protect access to internal data.
   boost::asio::detail::mutex mutex_;
@@ -197,6 +205,10 @@ class select_reactor
   timer_queue_set timer_queues_;
 
 #if defined(BOOST_ASIO_HAS_IOCP)
+  // Helper class to run the reactor loop in a thread.
+  class thread_function;
+  friend class thread_function;
+
   // Does the reactor loop thread need to stop.
   bool stop_thread_;
 
diff --git a/include/boost/asio/detail/service_registry.hpp b/include/boost/asio/detail/service_registry.hpp
index b5fa85bd01..7218848e4c 100644
--- a/include/boost/asio/detail/service_registry.hpp
+++ b/include/boost/asio/detail/service_registry.hpp
@@ -19,12 +19,16 @@
 #include <typeinfo>
 #include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/execution_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
+
+class io_context;
+
 namespace detail {
 
 template <typename T>
@@ -34,27 +38,34 @@ class service_registry
   : private noncopyable
 {
 public:
-  // Constructor. Adds the initial service.
-  template <typename Service, typename Arg>
-  service_registry(boost::asio::io_service& o,
-      Service* initial_service, Arg arg);
+  // Constructor.
+  BOOST_ASIO_DECL service_registry(execution_context& owner);
 
   // Destructor.
   BOOST_ASIO_DECL ~service_registry();
 
+  // Shutdown all services.
+  BOOST_ASIO_DECL void shutdown_services();
+
+  // Destroy all services.
+  BOOST_ASIO_DECL void destroy_services();
+
   // Notify all services of a fork event.
-  BOOST_ASIO_DECL void notify_fork(boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void notify_fork(execution_context::fork_event fork_ev);
 
-  // Get the first service object cast to the specified type. Called during
-  // io_service construction and so performs no locking or type checking.
+  // Get the service object corresponding to the specified service type. Will
+  // create a new service object automatically if no such object already
+  // exists. Ownership of the service object is not transferred to the caller.
   template <typename Service>
-  Service& first_service();
+  Service& use_service();
 
   // Get the service object corresponding to the specified service type. Will
   // create a new service object automatically if no such object already
   // exists. Ownership of the service object is not transferred to the caller.
+  // This overload is used for backwards compatibility with services that
+  // inherit from io_context::service.
   template <typename Service>
-  Service& use_service();
+  Service& use_service(io_context& owner);
 
   // Add a service object. Throws on error, in which case ownership of the
   // object is retained by the caller.
@@ -66,70 +77,79 @@ class service_registry
   bool has_service() const;
 
 private:
+  // Initalise a service's key when the key_type typedef is not available.
+  template <typename Service>
+  static void init_key(execution_context::service::key& key, ...);
+
+#if !defined(BOOST_ASIO_NO_TYPEID)
+  // Initalise a service's key when the key_type typedef is available.
+  template <typename Service>
+  static void init_key(execution_context::service::key& key,
+      typename enable_if<
+        is_base_of<typename Service::key_type, Service>::value>::type*);
+#endif // !defined(BOOST_ASIO_NO_TYPEID)
+
   // Initialise a service's key based on its id.
-  BOOST_ASIO_DECL static void init_key(
-      boost::asio::io_service::service::key& key,
-      const boost::asio::io_service::id& id);
+  BOOST_ASIO_DECL static void init_key_from_id(
+      execution_context::service::key& key,
+      const execution_context::id& id);
 
 #if !defined(BOOST_ASIO_NO_TYPEID)
   // Initialise a service's key based on its id.
   template <typename Service>
-  static void init_key(boost::asio::io_service::service::key& key,
-      const boost::asio::detail::service_id<Service>& /*id*/);
+  static void init_key_from_id(execution_context::service::key& key,
+      const service_id<Service>& /*id*/);
 #endif // !defined(BOOST_ASIO_NO_TYPEID)
 
   // Check if a service matches the given id.
   BOOST_ASIO_DECL static bool keys_match(
-      const boost::asio::io_service::service::key& key1,
-      const boost::asio::io_service::service::key& key2);
+      const execution_context::service::key& key1,
+      const execution_context::service::key& key2);
 
   // The type of a factory function used for creating a service instance.
-  typedef boost::asio::io_service::service*
-    (*factory_type)(boost::asio::io_service&);
+  typedef execution_context::service*(*factory_type)(void*);
 
   // Factory function for creating a service instance.
-  template <typename Service>
-  static boost::asio::io_service::service* create(
-      boost::asio::io_service& owner);
+  template <typename Service, typename Owner>
+  static execution_context::service* create(void* owner);
 
   // Destroy a service instance.
-  BOOST_ASIO_DECL static void destroy(
-      boost::asio::io_service::service* service);
+  BOOST_ASIO_DECL static void destroy(execution_context::service* service);
 
   // Helper class to manage service pointers.
   struct auto_service_ptr;
   friend struct auto_service_ptr;
   struct auto_service_ptr
   {
-    boost::asio::io_service::service* ptr_;
+    execution_context::service* ptr_;
     ~auto_service_ptr() { destroy(ptr_); }
   };
 
   // Get the service object corresponding to the specified service key. Will
   // create a new service object automatically if no such object already
   // exists. Ownership of the service object is not transferred to the caller.
-  BOOST_ASIO_DECL boost::asio::io_service::service* do_use_service(
-      const boost::asio::io_service::service::key& key,
-      factory_type factory);
+  BOOST_ASIO_DECL execution_context::service* do_use_service(
+      const execution_context::service::key& key,
+      factory_type factory, void* owner);
 
   // Add a service object. Throws on error, in which case ownership of the
   // object is retained by the caller.
   BOOST_ASIO_DECL void do_add_service(
-      const boost::asio::io_service::service::key& key,
-      boost::asio::io_service::service* new_service);
+      const execution_context::service::key& key,
+      execution_context::service* new_service);
 
   // Check whether a service object with the specified key already exists.
   BOOST_ASIO_DECL bool do_has_service(
-      const boost::asio::io_service::service::key& key) const;
+      const execution_context::service::key& key) const;
 
   // Mutex to protect access to internal data.
   mutable boost::asio::detail::mutex mutex_;
 
   // The owner of this service registry and the services it contains.
-  boost::asio::io_service& owner_;
+  execution_context& owner_;
 
   // The first service in the list of contained services.
-  boost::asio::io_service::service* first_service_;
+  execution_context::service* first_service_;
 };
 
 } // namespace detail
diff --git a/include/boost/asio/detail/shared_ptr.hpp b/include/boost/asio/detail/shared_ptr.hpp
deleted file mode 100644
index f26c645121..0000000000
--- a/include/boost/asio/detail/shared_ptr.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-//
-// detail/shared_ptr.hpp
-// ~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_DETAIL_SHARED_PTR_HPP
-#define BOOST_ASIO_DETAIL_SHARED_PTR_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-
-#if defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-# include <memory>
-#else // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-# include <boost/shared_ptr.hpp>
-#endif // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-
-namespace boost {
-namespace asio {
-namespace detail {
-
-#if defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-using std::shared_ptr;
-#else // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-using boost::shared_ptr;
-#endif // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-
-} // namespace detail
-} // namespace asio
-} // namespace boost
-
-#endif // BOOST_ASIO_DETAIL_SHARED_PTR_HPP
diff --git a/include/boost/asio/detail/signal_handler.hpp b/include/boost/asio/detail/signal_handler.hpp
index edad41b8ee..6ea723a27a 100644
--- a/include/boost/asio/detail/signal_handler.hpp
+++ b/include/boost/asio/detail/signal_handler.hpp
@@ -16,10 +16,12 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/handler_work.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/signal_op.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -38,17 +40,19 @@ class signal_handler : public signal_op
     : signal_op(&signal_handler::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(h))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     signal_handler* h(static_cast<signal_handler*>(base));
     ptr p = { boost::asio::detail::addressof(h->handler_), h, h };
+    handler_work<Handler> w(h->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((h));
+    BOOST_ASIO_HANDLER_COMPLETION((*h));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -66,7 +70,7 @@ class signal_handler : public signal_op
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/signal_set_service.hpp b/include/boost/asio/detail/signal_set_service.hpp
index a023ebb66f..f27f8652c4 100644
--- a/include/boost/asio/detail/signal_set_service.hpp
+++ b/include/boost/asio/detail/signal_set_service.hpp
@@ -20,9 +20,9 @@
 #include <cstddef>
 #include <signal.h>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/op_queue.hpp>
 #include <boost/asio/detail/signal_handler.hpp>
 #include <boost/asio/detail/signal_op.hpp>
@@ -48,7 +48,8 @@ extern BOOST_ASIO_DECL struct signal_state* get_signal_state();
 
 extern "C" BOOST_ASIO_DECL void boost_asio_signal_handler(int signal_number);
 
-class signal_set_service
+class signal_set_service :
+  public service_base<signal_set_service>
 {
 public:
   // Type used for tracking an individual signal registration.
@@ -109,17 +110,17 @@ class signal_set_service
   };
 
   // Constructor.
-  BOOST_ASIO_DECL signal_set_service(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL signal_set_service(boost::asio::io_context& io_context);
 
   // Destructor.
   BOOST_ASIO_DECL ~signal_set_service();
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Perform fork-related housekeeping.
-  BOOST_ASIO_DECL void fork_service(
-      boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void notify_fork(
+      boost::asio::io_context::fork_event fork_ev);
 
   // Construct a new signal_set implementation.
   BOOST_ASIO_DECL void construct(implementation_type& impl);
@@ -150,11 +151,11 @@ class signal_set_service
     // Allocate and construct an operation to wrap the handler.
     typedef signal_handler<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "signal_set", &impl, "async_wait"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_.context(),
+          *p.p, "signal_set", &impl, 0, "async_wait"));
 
     start_wait_op(impl, p.p);
     p.v = p.p = 0;
@@ -179,8 +180,8 @@ class signal_set_service
   // Helper function to start a wait operation.
   BOOST_ASIO_DECL void start_wait_op(implementation_type& impl, signal_op* op);
 
-  // The io_service instance used for dispatching handlers.
-  io_service_impl& io_service_;
+  // The io_context instance used for dispatching handlers.
+  io_context_impl& io_context_;
 
 #if !defined(BOOST_ASIO_WINDOWS) \
   && !defined(BOOST_ASIO_WINDOWS_RUNTIME) \
diff --git a/include/boost/asio/detail/socket_ops.hpp b/include/boost/asio/detail/socket_ops.hpp
index 136a3f01f7..8d39ab8737 100644
--- a/include/boost/asio/detail/socket_ops.hpp
+++ b/include/boost/asio/detail/socket_ops.hpp
@@ -18,9 +18,8 @@
 #include <boost/asio/detail/config.hpp>
 
 #include <boost/system/error_code.hpp>
-#include <boost/asio/detail/shared_ptr.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/socket_types.hpp>
-#include <boost/asio/detail/weak_ptr.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -265,12 +264,16 @@ BOOST_ASIO_DECL int select(int nfds, fd_set* readfds, fd_set* writefds,
     fd_set* exceptfds, timeval* timeout, boost::system::error_code& ec);
 
 BOOST_ASIO_DECL int poll_read(socket_type s,
-    state_type state, boost::system::error_code& ec);
+    state_type state, int msec, boost::system::error_code& ec);
 
 BOOST_ASIO_DECL int poll_write(socket_type s,
-    state_type state, boost::system::error_code& ec);
+    state_type state, int msec, boost::system::error_code& ec);
 
-BOOST_ASIO_DECL int poll_connect(socket_type s, boost::system::error_code& ec);
+BOOST_ASIO_DECL int poll_error(socket_type s,
+    state_type state, int msec, boost::system::error_code& ec);
+
+BOOST_ASIO_DECL int poll_connect(socket_type s,
+    int msec, boost::system::error_code& ec);
 
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
diff --git a/include/boost/asio/detail/socket_types.hpp b/include/boost/asio/detail/socket_types.hpp
index 0768f70077..859d59feb1 100644
--- a/include/boost/asio/detail/socket_types.hpp
+++ b/include/boost/asio/detail/socket_types.hpp
@@ -152,6 +152,7 @@ typedef int signed_size_type;
 # define BOOST_ASIO_OS_DEF_SO_DONTROUTE 0x10
 # define BOOST_ASIO_OS_DEF_SO_KEEPALIVE 0x8
 # define BOOST_ASIO_OS_DEF_SO_LINGER 0x80
+# define BOOST_ASIO_OS_DEF_SO_OOBINLINE 0x100
 # define BOOST_ASIO_OS_DEF_SO_SNDBUF 0x1001
 # define BOOST_ASIO_OS_DEF_SO_RCVBUF 0x1002
 # define BOOST_ASIO_OS_DEF_SO_SNDLOWAT 0x1003
@@ -236,6 +237,7 @@ typedef int signed_size_type;
 # define BOOST_ASIO_OS_DEF_SO_DONTROUTE SO_DONTROUTE
 # define BOOST_ASIO_OS_DEF_SO_KEEPALIVE SO_KEEPALIVE
 # define BOOST_ASIO_OS_DEF_SO_LINGER SO_LINGER
+# define BOOST_ASIO_OS_DEF_SO_OOBINLINE SO_OOBINLINE
 # define BOOST_ASIO_OS_DEF_SO_SNDBUF SO_SNDBUF
 # define BOOST_ASIO_OS_DEF_SO_RCVBUF SO_RCVBUF
 # define BOOST_ASIO_OS_DEF_SO_SNDLOWAT SO_SNDLOWAT
@@ -351,6 +353,7 @@ typedef int signed_size_type;
 # define BOOST_ASIO_OS_DEF_SO_DONTROUTE SO_DONTROUTE
 # define BOOST_ASIO_OS_DEF_SO_KEEPALIVE SO_KEEPALIVE
 # define BOOST_ASIO_OS_DEF_SO_LINGER SO_LINGER
+# define BOOST_ASIO_OS_DEF_SO_OOBINLINE SO_OOBINLINE
 # define BOOST_ASIO_OS_DEF_SO_SNDBUF SO_SNDBUF
 # define BOOST_ASIO_OS_DEF_SO_RCVBUF SO_RCVBUF
 # define BOOST_ASIO_OS_DEF_SO_SNDLOWAT SO_SNDLOWAT
diff --git a/include/boost/asio/detail/solaris_fenced_block.hpp b/include/boost/asio/detail/solaris_fenced_block.hpp
index 2aef0229f1..5653a8b4c4 100644
--- a/include/boost/asio/detail/solaris_fenced_block.hpp
+++ b/include/boost/asio/detail/solaris_fenced_block.hpp
@@ -20,6 +20,7 @@
 #if defined(__sun)
 
 #include <atomic.h>
+#include <boost/asio/detail/noncopyable.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
diff --git a/include/boost/asio/detail/std_global.hpp b/include/boost/asio/detail/std_global.hpp
new file mode 100644
index 0000000000..f0936e5ea9
--- /dev/null
+++ b/include/boost/asio/detail/std_global.hpp
@@ -0,0 +1,72 @@
+//
+// detail/std_global.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_STD_GLOBAL_HPP
+#define BOOST_ASIO_DETAIL_STD_GLOBAL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_STD_CALL_ONCE)
+
+#include <exception>
+#include <mutex>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T>
+struct std_global_impl
+{
+  // Helper function to perform initialisation.
+  static void do_init()
+  {
+    instance_.ptr_ = new T;
+  }
+
+  // Destructor automatically cleans up the global.
+  ~std_global_impl()
+  {
+    delete ptr_;
+  }
+
+  static std::once_flag init_once_;
+  static std_global_impl instance_;
+  T* ptr_;
+};
+
+template <typename T>
+std::once_flag std_global_impl<T>::init_once_;
+
+template <typename T>
+std_global_impl<T> std_global_impl<T>::instance_;
+
+template <typename T>
+T& std_global()
+{
+  std::call_once(std_global_impl<T>::init_once_, &std_global_impl<T>::do_init);
+  return *std_global_impl<T>::instance_.ptr_;
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // defined(BOOST_ASIO_HAS_STD_CALL_ONCE)
+
+#endif // BOOST_ASIO_DETAIL_STD_GLOBAL_HPP
diff --git a/include/boost/asio/detail/std_thread.hpp b/include/boost/asio/detail/std_thread.hpp
index cd2a61dac2..35bcc1722c 100644
--- a/include/boost/asio/detail/std_thread.hpp
+++ b/include/boost/asio/detail/std_thread.hpp
@@ -52,6 +52,12 @@ class std_thread
       thread_.join();
   }
 
+  // Get number of CPUs.
+  static std::size_t hardware_concurrency()
+  {
+    return std::thread::hardware_concurrency();
+  }
+
 private:
   std::thread thread_;
 };
diff --git a/include/boost/asio/detail/strand_executor_service.hpp b/include/boost/asio/detail/strand_executor_service.hpp
new file mode 100644
index 0000000000..38728d4610
--- /dev/null
+++ b/include/boost/asio/detail/strand_executor_service.hpp
@@ -0,0 +1,140 @@
+//
+// detail/strand_executor_service.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_STRAND_EXECUTOR_SERVICE_HPP
+#define BOOST_ASIO_DETAIL_STRAND_EXECUTOR_SERVICE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/atomic_count.hpp>
+#include <boost/asio/detail/executor_op.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/mutex.hpp>
+#include <boost/asio/detail/op_queue.hpp>
+#include <boost/asio/detail/scheduler_operation.hpp>
+#include <boost/asio/detail/scoped_ptr.hpp>
+#include <boost/asio/execution_context.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+// Default service implementation for a strand.
+class strand_executor_service
+  : public execution_context_service_base<strand_executor_service>
+{
+public:
+  // The underlying implementation of a strand.
+  class strand_impl
+  {
+  public:
+    BOOST_ASIO_DECL ~strand_impl();
+
+  private:
+    friend class strand_executor_service;
+
+    // Mutex to protect access to internal data.
+    mutex* mutex_;
+
+    // Indicates whether the strand is currently "locked" by a handler. This
+    // means that there is a handler upcall in progress, or that the strand
+    // itself has been scheduled in order to invoke some pending handlers.
+    bool locked_;
+
+    // The handlers that are waiting on the strand but should not be run until
+    // after the next time the strand is scheduled. This queue must only be
+    // modified while the mutex is locked.
+    op_queue<scheduler_operation> waiting_queue_;
+
+    // The handlers that are ready to be run. Logically speaking, these are the
+    // handlers that hold the strand's lock. The ready queue is only modified
+    // from within the strand and so may be accessed without locking the mutex.
+    op_queue<scheduler_operation> ready_queue_;
+
+    // Pointers to adjacent handle implementations in linked list.
+    strand_impl* next_;
+    strand_impl* prev_;
+
+    // The strand service in where the implementation is held.
+    strand_executor_service* service_;
+  };
+
+  typedef shared_ptr<strand_impl> implementation_type;
+
+  // Construct a new strand service for the specified context.
+  BOOST_ASIO_DECL explicit strand_executor_service(execution_context& context);
+
+  // Destroy all user-defined handler objects owned by the service.
+  BOOST_ASIO_DECL void shutdown();
+
+  // Create a new strand_executor implementation.
+  BOOST_ASIO_DECL implementation_type create_implementation();
+
+  // Request invocation of the given function.
+  template <typename Executor, typename Function, typename Allocator>
+  static void dispatch(const implementation_type& impl, Executor& ex,
+      BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
+
+  // Request invocation of the given function and return immediately.
+  template <typename Executor, typename Function, typename Allocator>
+  static void post(const implementation_type& impl, Executor& ex,
+      BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
+
+  // Request invocation of the given function and return immediately.
+  template <typename Executor, typename Function, typename Allocator>
+  static void defer(const implementation_type& impl, Executor& ex,
+      BOOST_ASIO_MOVE_ARG(Function) function, const Allocator& a);
+
+  // Determine whether the strand is running in the current thread.
+  BOOST_ASIO_DECL static bool running_in_this_thread(
+      const implementation_type& impl);
+
+private:
+  friend class strand_impl;
+  template <typename Executor> class invoker;
+
+  // Adds a function to the strand. Returns true if it acquires the lock.
+  BOOST_ASIO_DECL static bool enqueue(const implementation_type& impl,
+      scheduler_operation* op);
+
+  // Mutex to protect access to the service-wide state.
+  mutex mutex_;
+
+  // Number of mutexes shared between all strand objects.
+  enum { num_mutexes = 193 };
+
+  // Pool of mutexes.
+  scoped_ptr<mutex> mutexes_[num_mutexes];
+
+  // Extra value used when hashing to prevent recycled memory locations from
+  // getting the same mutex.
+  std::size_t salt_;
+
+  // The head of a linked list of all implementations.
+  strand_impl* impl_list_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/detail/impl/strand_executor_service.hpp>
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/detail/impl/strand_executor_service.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+#endif // BOOST_ASIO_DETAIL_STRAND_EXECUTOR_SERVICE_HPP
diff --git a/include/boost/asio/detail/strand_service.hpp b/include/boost/asio/detail/strand_service.hpp
index 8a94e58e36..e9d05b3ae7 100644
--- a/include/boost/asio/detail/strand_service.hpp
+++ b/include/boost/asio/detail/strand_service.hpp
@@ -16,7 +16,7 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/op_queue.hpp>
 #include <boost/asio/detail/operation.hpp>
@@ -75,20 +75,20 @@ class strand_service
 
   typedef strand_impl* implementation_type;
 
-  // Construct a new strand service for the specified io_service.
-  BOOST_ASIO_DECL explicit strand_service(boost::asio::io_service& io_service);
+  // Construct a new strand service for the specified io_context.
+  BOOST_ASIO_DECL explicit strand_service(boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Construct a new strand implementation.
   BOOST_ASIO_DECL void construct(implementation_type& impl);
 
-  // Request the io_service to invoke the given handler.
+  // Request the io_context to invoke the given handler.
   template <typename Handler>
   void dispatch(implementation_type& impl, Handler& handler);
 
-  // Request the io_service to invoke the given handler and return immediately.
+  // Request the io_context to invoke the given handler and return immediately.
   template <typename Handler>
   void post(implementation_type& impl, Handler& handler);
 
@@ -105,12 +105,12 @@ class strand_service
   BOOST_ASIO_DECL void do_post(implementation_type& impl,
       operation* op, bool is_continuation);
 
-  BOOST_ASIO_DECL static void do_complete(io_service_impl* owner,
+  BOOST_ASIO_DECL static void do_complete(void* owner,
       operation* base, const boost::system::error_code& ec,
       std::size_t bytes_transferred);
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_;
+  // The io_context implementation used to post completions.
+  io_context_impl& io_context_;
 
   // Mutex to protect access to the array of implementations.
   boost::asio::detail::mutex mutex_;
diff --git a/include/boost/asio/detail/string_view.hpp b/include/boost/asio/detail/string_view.hpp
new file mode 100644
index 0000000000..3d0a24f4c6
--- /dev/null
+++ b/include/boost/asio/detail/string_view.hpp
@@ -0,0 +1,47 @@
+//
+// detail/string_view.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_STRING_VIEW_HPP
+#define BOOST_ASIO_DETAIL_STRING_VIEW_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+#if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+# include <experimental/string_view>
+#else // defined(BOOST_ASIO_HAS_EXPERIMENTAL_STRING_VIEW)
+# include <string_view>
+#endif // defined(BOOST_ASIO_HAS_EXPERIMENTAL_STRING_VIEW)
+
+namespace boost {
+namespace asio {
+
+#if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+using std::experimental::basic_string_view;
+using std::experimental::string_view;
+#else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+using std::basic_string_view;
+using std::string_view;
+#endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+
+} // namespace asio
+} // namespace boost
+
+# define BOOST_ASIO_STRING_VIEW_PARAM boost::asio::string_view
+#else // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# define BOOST_ASIO_STRING_VIEW_PARAM const std::string&
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+#endif // BOOST_ASIO_DETAIL_STRING_VIEW_HPP
diff --git a/include/boost/asio/detail/thread.hpp b/include/boost/asio/detail/thread.hpp
index f385fc85a1..e10040e972 100644
--- a/include/boost/asio/detail/thread.hpp
+++ b/include/boost/asio/detail/thread.hpp
@@ -20,8 +20,10 @@
 #if !defined(BOOST_ASIO_HAS_THREADS)
 # include <boost/asio/detail/null_thread.hpp>
 #elif defined(BOOST_ASIO_WINDOWS)
-# if defined(BOOST_ASIO_WINDOWS_APP) || defined(UNDER_CE)
-#  include <boost/asio/detail/winapi_thread.hpp>
+# if defined(UNDER_CE)
+#  include <boost/asio/detail/wince_thread.hpp>
+# elif defined(BOOST_ASIO_WINDOWS_APP)
+#  include <boost/asio/detail/winapp_thread.hpp>
 # else
 #  include <boost/asio/detail/win_thread.hpp>
 # endif
@@ -40,8 +42,10 @@ namespace detail {
 #if !defined(BOOST_ASIO_HAS_THREADS)
 typedef null_thread thread;
 #elif defined(BOOST_ASIO_WINDOWS)
-# if defined(BOOST_ASIO_WINDOWS_APP) || defined(UNDER_CE)
-typedef winapi_thread thread;
+# if defined(UNDER_CE)
+typedef wince_thread thread;
+# elif defined(BOOST_ASIO_WINDOWS_APP)
+typedef winapp_thread thread;
 # else
 typedef win_thread thread;
 # endif
diff --git a/include/boost/asio/detail/thread_context.hpp b/include/boost/asio/detail/thread_context.hpp
new file mode 100644
index 0000000000..8c059ccb02
--- /dev/null
+++ b/include/boost/asio/detail/thread_context.hpp
@@ -0,0 +1,44 @@
+//
+// detail/thread_context.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_THREAD_CONTEXT_HPP
+#define BOOST_ASIO_DETAIL_THREAD_CONTEXT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <climits>
+#include <cstddef>
+#include <boost/asio/detail/call_stack.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+class thread_info_base;
+
+// Base class for things that manage threads (scheduler, win_iocp_io_context).
+class thread_context
+{
+public:
+  // Per-thread call stack to track the state of each thread in the context.
+  typedef call_stack<thread_context, thread_info_base> thread_call_stack;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_THREAD_CONTEXT_HPP
diff --git a/include/boost/asio/detail/thread_group.hpp b/include/boost/asio/detail/thread_group.hpp
new file mode 100644
index 0000000000..2451e8f3b7
--- /dev/null
+++ b/include/boost/asio/detail/thread_group.hpp
@@ -0,0 +1,91 @@
+//
+// detail/thread_group.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_THREAD_GROUP_HPP
+#define BOOST_ASIO_DETAIL_THREAD_GROUP_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/scoped_ptr.hpp>
+#include <boost/asio/detail/thread.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+class thread_group
+{
+public:
+  // Constructor initialises an empty thread group.
+  thread_group()
+    : first_(0)
+  {
+  }
+
+  // Destructor joins any remaining threads in the group.
+  ~thread_group()
+  {
+    join();
+  }
+
+  // Create a new thread in the group.
+  template <typename Function>
+  void create_thread(Function f)
+  {
+    first_ = new item(f, first_);
+  }
+
+  // Create new threads in the group.
+  template <typename Function>
+  void create_threads(Function f, std::size_t num_threads)
+  {
+    for (std::size_t i = 0; i < num_threads; ++i)
+      create_thread(f);
+  }
+
+  // Wait for all threads in the group to exit.
+  void join()
+  {
+    while (first_)
+    {
+      first_->thread_.join();
+      item* tmp = first_;
+      first_ = first_->next_;
+      delete tmp;
+    }
+  }
+
+private:
+  // Structure used to track a single thread in the group.
+  struct item
+  {
+    template <typename Function>
+    explicit item(Function f, item* next)
+      : thread_(f),
+        next_(next)
+    {
+    }
+
+    boost::asio::detail::thread thread_;
+    item* next_;
+  };
+
+  // The first thread in the group.
+  item* first_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#endif // BOOST_ASIO_DETAIL_THREAD_GROUP_HPP
diff --git a/include/boost/asio/detail/timer_queue.hpp b/include/boost/asio/detail/timer_queue.hpp
index cb848dfb3a..f8d48babad 100644
--- a/include/boost/asio/detail/timer_queue.hpp
+++ b/include/boost/asio/detail/timer_queue.hpp
@@ -47,7 +47,11 @@ class timer_queue
   class per_timer_data
   {
   public:
-    per_timer_data() : next_(0), prev_(0) {}
+    per_timer_data() :
+      heap_index_((std::numeric_limits<std::size_t>::max)()),
+      next_(0), prev_(0)
+    {
+    }
 
   private:
     friend class timer_queue;
@@ -189,6 +193,29 @@ class timer_queue
     return num_cancelled;
   }
 
+  // Move operations from one timer to another, empty timer.
+  void move_timer(per_timer_data& target, per_timer_data& source)
+  {
+    target.op_queue_.push(source.op_queue_);
+
+    target.heap_index_ = source.heap_index_;
+    source.heap_index_ = (std::numeric_limits<std::size_t>::max)();
+
+    if (target.heap_index_ < heap_.size())
+      heap_[target.heap_index_].timer_ = &target;
+
+    if (timers_ == &source)
+      timers_ = &target;
+    if (source.prev_)
+      source.prev_->next_ = &target;
+    if (source.next_)
+      source.next_->prev_= &target;
+    target.next_ = source.next_;
+    target.prev_ = source.prev_;
+    source.next_ = 0;
+    source.prev_ = 0;
+  }
+
 private:
   // Move the item at the given index up the heap to its correct position.
   void up_heap(std::size_t index)
diff --git a/include/boost/asio/detail/timer_queue_ptime.hpp b/include/boost/asio/detail/timer_queue_ptime.hpp
index 0693acca83..d1934f1375 100644
--- a/include/boost/asio/detail/timer_queue_ptime.hpp
+++ b/include/boost/asio/detail/timer_queue_ptime.hpp
@@ -15,13 +15,15 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+
 #include <boost/asio/time_traits.hpp>
 #include <boost/asio/detail/timer_queue.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
-#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-
 namespace boost {
 namespace asio {
 namespace detail {
@@ -76,6 +78,10 @@ class timer_queue<time_traits<boost::posix_time::ptime> >
       per_timer_data& timer, op_queue<operation>& ops,
       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
 
+  // Move operations from one timer to another, empty timer.
+  BOOST_ASIO_DECL void move_timer(per_timer_data& target,
+      per_timer_data& source);
+
 private:
   timer_queue<forwarding_posix_time_traits> impl_;
 };
@@ -84,12 +90,12 @@ class timer_queue<time_traits<boost::posix_time::ptime> >
 } // namespace asio
 } // namespace boost
 
-#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-
 #include <boost/asio/detail/pop_options.hpp>
 
 #if defined(BOOST_ASIO_HEADER_ONLY)
 # include <boost/asio/detail/impl/timer_queue_ptime.ipp>
 #endif // defined(BOOST_ASIO_HEADER_ONLY)
 
+#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+
 #endif // BOOST_ASIO_DETAIL_TIMER_QUEUE_PTIME_HPP
diff --git a/include/boost/asio/detail/timer_scheduler.hpp b/include/boost/asio/detail/timer_scheduler.hpp
index 49dc113d10..290d0b0680 100644
--- a/include/boost/asio/detail/timer_scheduler.hpp
+++ b/include/boost/asio/detail/timer_scheduler.hpp
@@ -21,7 +21,7 @@
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/winrt_timer_scheduler.hpp>
 #elif defined(BOOST_ASIO_HAS_IOCP)
-# include <boost/asio/detail/win_iocp_io_service.hpp>
+# include <boost/asio/detail/win_iocp_io_context.hpp>
 #elif defined(BOOST_ASIO_HAS_EPOLL)
 # include <boost/asio/detail/epoll_reactor.hpp>
 #elif defined(BOOST_ASIO_HAS_KQUEUE)
diff --git a/include/boost/asio/detail/timer_scheduler_fwd.hpp b/include/boost/asio/detail/timer_scheduler_fwd.hpp
index bf732a63d3..de3d3bd350 100644
--- a/include/boost/asio/detail/timer_scheduler_fwd.hpp
+++ b/include/boost/asio/detail/timer_scheduler_fwd.hpp
@@ -24,7 +24,7 @@ namespace detail {
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 typedef class winrt_timer_scheduler timer_scheduler;
 #elif defined(BOOST_ASIO_HAS_IOCP)
-typedef class win_iocp_io_service timer_scheduler;
+typedef class win_iocp_io_context timer_scheduler;
 #elif defined(BOOST_ASIO_HAS_EPOLL)
 typedef class epoll_reactor timer_scheduler;
 #elif defined(BOOST_ASIO_HAS_KQUEUE)
diff --git a/include/boost/asio/detail/type_traits.hpp b/include/boost/asio/detail/type_traits.hpp
index 53a73a0eb1..1556e597e0 100644
--- a/include/boost/asio/detail/type_traits.hpp
+++ b/include/boost/asio/detail/type_traits.hpp
@@ -21,6 +21,11 @@
 # include <type_traits>
 #else // defined(BOOST_ASIO_HAS_TYPE_TRAITS)
 # include <boost/type_traits/add_const.hpp>
+# include <boost/type_traits/conditional.hpp>
+# include <boost/type_traits/decay.hpp>
+# include <boost/type_traits/integral_constant.hpp>
+# include <boost/type_traits/is_base_of.hpp>
+# include <boost/type_traits/is_class.hpp>
 # include <boost/type_traits/is_const.hpp>
 # include <boost/type_traits/is_convertible.hpp>
 # include <boost/type_traits/is_function.hpp>
@@ -28,6 +33,7 @@
 # include <boost/type_traits/remove_pointer.hpp>
 # include <boost/type_traits/remove_reference.hpp>
 # include <boost/utility/enable_if.hpp>
+# include <boost/utility/result_of.hpp>
 #endif // defined(BOOST_ASIO_HAS_TYPE_TRAITS)
 
 namespace boost {
@@ -35,23 +41,39 @@ namespace asio {
 
 #if defined(BOOST_ASIO_HAS_STD_TYPE_TRAITS)
 using std::add_const;
+using std::conditional;
+using std::decay;
 using std::enable_if;
+using std::false_type;
+using std::integral_constant;
+using std::is_base_of;
+using std::is_class;
 using std::is_const;
 using std::is_convertible;
 using std::is_function;
 using std::is_same;
 using std::remove_pointer;
 using std::remove_reference;
+using std::result_of;
+using std::true_type;
 #else // defined(BOOST_ASIO_HAS_STD_TYPE_TRAITS)
 using boost::add_const;
 template <bool Condition, typename Type = void>
 struct enable_if : boost::enable_if_c<Condition, Type> {};
+using boost::conditional;
+using boost::decay;
+using boost::false_type;
+using boost::integral_constant;
+using boost::is_base_of;
+using boost::is_class;
 using boost::is_const;
 using boost::is_convertible;
 using boost::is_function;
 using boost::is_same;
 using boost::remove_pointer;
 using boost::remove_reference;
+using boost::result_of;
+using boost::true_type;
 #endif // defined(BOOST_ASIO_HAS_STD_TYPE_TRAITS)
 
 } // namespace asio
diff --git a/include/boost/asio/detail/variadic_templates.hpp b/include/boost/asio/detail/variadic_templates.hpp
index 6d55bc7a7c..228a6542e9 100644
--- a/include/boost/asio/detail/variadic_templates.hpp
+++ b/include/boost/asio/detail/variadic_templates.hpp
@@ -34,27 +34,83 @@
 
 # define BOOST_ASIO_VARIADIC_TARGS(n) BOOST_ASIO_VARIADIC_TARGS_##n
 
-# define BOOST_ASIO_VARIADIC_TARGS_1 x1
-# define BOOST_ASIO_VARIADIC_TARGS_2 x1, x2
-# define BOOST_ASIO_VARIADIC_TARGS_3 x1, x2, x3
-# define BOOST_ASIO_VARIADIC_TARGS_4 x1, x2, x3, x4
-# define BOOST_ASIO_VARIADIC_TARGS_5 x1, x2, x3, x4, x5
-
-# define BOOST_ASIO_VARIADIC_PARAMS(n) BOOST_ASIO_VARIADIC_PARAMS_##n
-
-# define BOOST_ASIO_VARIADIC_PARAMS_1 T1 x1
-# define BOOST_ASIO_VARIADIC_PARAMS_2 T1 x1, T2 x2
-# define BOOST_ASIO_VARIADIC_PARAMS_3 T1 x1, T2 x2, T3 x3
-# define BOOST_ASIO_VARIADIC_PARAMS_4 T1 x1, T2 x2, T3 x3, T4 x4
-# define BOOST_ASIO_VARIADIC_PARAMS_5 T1 x1, T2 x2, T3 x3, T4 x4, T5 x5
-
-# define BOOST_ASIO_VARIADIC_ARGS(n) BOOST_ASIO_VARIADIC_ARGS_##n
-
-# define BOOST_ASIO_VARIADIC_ARGS_1 x1
-# define BOOST_ASIO_VARIADIC_ARGS_2 x1, x2
-# define BOOST_ASIO_VARIADIC_ARGS_3 x1, x2, x3
-# define BOOST_ASIO_VARIADIC_ARGS_4 x1, x2, x3, x4
-# define BOOST_ASIO_VARIADIC_ARGS_5 x1, x2, x3, x4, x5
+# define BOOST_ASIO_VARIADIC_TARGS_1 T1
+# define BOOST_ASIO_VARIADIC_TARGS_2 T1, T2
+# define BOOST_ASIO_VARIADIC_TARGS_3 T1, T2, T3
+# define BOOST_ASIO_VARIADIC_TARGS_4 T1, T2, T3, T4
+# define BOOST_ASIO_VARIADIC_TARGS_5 T1, T2, T3, T4, T5
+
+# define BOOST_ASIO_VARIADIC_BYVAL_PARAMS(n) \
+  BOOST_ASIO_VARIADIC_BYVAL_PARAMS_##n
+
+# define BOOST_ASIO_VARIADIC_BYVAL_PARAMS_1 T1 x1
+# define BOOST_ASIO_VARIADIC_BYVAL_PARAMS_2 T1 x1, T2 x2
+# define BOOST_ASIO_VARIADIC_BYVAL_PARAMS_3 T1 x1, T2 x2, T3 x3
+# define BOOST_ASIO_VARIADIC_BYVAL_PARAMS_4 T1 x1, T2 x2, T3 x3, T4 x4
+# define BOOST_ASIO_VARIADIC_BYVAL_PARAMS_5 T1 x1, T2 x2, T3 x3, T4 x4, T5 x5
+
+# define BOOST_ASIO_VARIADIC_BYVAL_ARGS(n) \
+  BOOST_ASIO_VARIADIC_BYVAL_ARGS_##n
+
+# define BOOST_ASIO_VARIADIC_BYVAL_ARGS_1 x1
+# define BOOST_ASIO_VARIADIC_BYVAL_ARGS_2 x1, x2
+# define BOOST_ASIO_VARIADIC_BYVAL_ARGS_3 x1, x2, x3
+# define BOOST_ASIO_VARIADIC_BYVAL_ARGS_4 x1, x2, x3, x4
+# define BOOST_ASIO_VARIADIC_BYVAL_ARGS_5 x1, x2, x3, x4, x5
+
+# define BOOST_ASIO_VARIADIC_MOVE_PARAMS(n) \
+  BOOST_ASIO_VARIADIC_MOVE_PARAMS_##n
+
+# define BOOST_ASIO_VARIADIC_MOVE_PARAMS_1 \
+  BOOST_ASIO_MOVE_ARG(T1) x1
+# define BOOST_ASIO_VARIADIC_MOVE_PARAMS_2 \
+  BOOST_ASIO_MOVE_ARG(T1) x1, BOOST_ASIO_MOVE_ARG(T2) x2
+# define BOOST_ASIO_VARIADIC_MOVE_PARAMS_3 \
+  BOOST_ASIO_MOVE_ARG(T1) x1, BOOST_ASIO_MOVE_ARG(T2) x2, \
+  BOOST_ASIO_MOVE_ARG(T3) x3
+# define BOOST_ASIO_VARIADIC_MOVE_PARAMS_4 \
+  BOOST_ASIO_MOVE_ARG(T1) x1, BOOST_ASIO_MOVE_ARG(T2) x2, \
+  BOOST_ASIO_MOVE_ARG(T3) x3, BOOST_ASIO_MOVE_ARG(T4) x4
+# define BOOST_ASIO_VARIADIC_MOVE_PARAMS_5 \
+  BOOST_ASIO_MOVE_ARG(T1) x1, BOOST_ASIO_MOVE_ARG(T2) x2, \
+  BOOST_ASIO_MOVE_ARG(T3) x3, BOOST_ASIO_MOVE_ARG(T4) x4, \
+  BOOST_ASIO_MOVE_ARG(T5) x5
+
+# define BOOST_ASIO_VARIADIC_MOVE_ARGS(n) \
+  BOOST_ASIO_VARIADIC_MOVE_ARGS_##n
+
+# define BOOST_ASIO_VARIADIC_MOVE_ARGS_1 \
+  BOOST_ASIO_MOVE_CAST(T1)(x1)
+# define BOOST_ASIO_VARIADIC_MOVE_ARGS_2 \
+  BOOST_ASIO_MOVE_CAST(T1)(x1), BOOST_ASIO_MOVE_CAST(T2)(x2)
+# define BOOST_ASIO_VARIADIC_MOVE_ARGS_3 \
+  BOOST_ASIO_MOVE_CAST(T1)(x1), BOOST_ASIO_MOVE_CAST(T2)(x2), \
+  BOOST_ASIO_MOVE_CAST(T3)(x3)
+# define BOOST_ASIO_VARIADIC_MOVE_ARGS_4 \
+  BOOST_ASIO_MOVE_CAST(T1)(x1), BOOST_ASIO_MOVE_CAST(T2)(x2), \
+  BOOST_ASIO_MOVE_CAST(T3)(x3), BOOST_ASIO_MOVE_CAST(T4)(x4)
+# define BOOST_ASIO_VARIADIC_MOVE_ARGS_5 \
+  BOOST_ASIO_MOVE_CAST(T1)(x1), BOOST_ASIO_MOVE_CAST(T2)(x2), \
+  BOOST_ASIO_MOVE_CAST(T3)(x3), BOOST_ASIO_MOVE_CAST(T4)(x4), \
+  BOOST_ASIO_MOVE_CAST(T5)(x5)
+
+# define BOOST_ASIO_VARIADIC_DECAY(n) \
+  BOOST_ASIO_VARIADIC_DECAY_##n
+
+# define BOOST_ASIO_VARIADIC_DECAY_1 \
+  typename decay<T1>::type
+# define BOOST_ASIO_VARIADIC_DECAY_2 \
+  typename decay<T1>::type, typename decay<T2>::type
+# define BOOST_ASIO_VARIADIC_DECAY_3 \
+  typename decay<T1>::type, typename decay<T2>::type, \
+  typename decay<T3>::type
+# define BOOST_ASIO_VARIADIC_DECAY_4 \
+  typename decay<T1>::type, typename decay<T2>::type, \
+  typename decay<T3>::type, typename decay<T4>::type
+# define BOOST_ASIO_VARIADIC_DECAY_5 \
+  typename decay<T1>::type, typename decay<T2>::type, \
+  typename decay<T3>::type, typename decay<T4>::type, \
+  typename decay<T5>::type
 
 # define BOOST_ASIO_VARIADIC_GENERATE(m) m(1) m(2) m(3) m(4) m(5)
 
diff --git a/include/boost/asio/detail/wait_handler.hpp b/include/boost/asio/detail/wait_handler.hpp
index 440dae1f18..5d520e8fb1 100644
--- a/include/boost/asio/detail/wait_handler.hpp
+++ b/include/boost/asio/detail/wait_handler.hpp
@@ -16,12 +16,12 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/wait_op.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -39,17 +39,19 @@ class wait_handler : public wait_op
     : wait_op(&wait_handler::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(h))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& /*ec*/,
       std::size_t /*bytes_transferred*/)
   {
     // Take ownership of the handler object.
     wait_handler* h(static_cast<wait_handler*>(base));
     ptr p = { boost::asio::detail::addressof(h->handler_), h, h };
+    handler_work<Handler> w(h->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((h));
+    BOOST_ASIO_HANDLER_COMPLETION((*h));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -67,7 +69,7 @@ class wait_handler : public wait_op
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/weak_ptr.hpp b/include/boost/asio/detail/weak_ptr.hpp
deleted file mode 100644
index 1870c0e0e8..0000000000
--- a/include/boost/asio/detail/weak_ptr.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-//
-// detail/weak_ptr.hpp
-// ~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_DETAIL_WEAK_PTR_HPP
-#define BOOST_ASIO_DETAIL_WEAK_PTR_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-
-#if defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-# include <memory>
-#else // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-# include <boost/weak_ptr.hpp>
-#endif // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-
-namespace boost {
-namespace asio {
-namespace detail {
-
-#if defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-using std::weak_ptr;
-#else // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-using boost::weak_ptr;
-#endif // defined(BOOST_ASIO_HAS_STD_SHARED_PTR)
-
-} // namespace detail
-} // namespace asio
-} // namespace boost
-
-#endif // BOOST_ASIO_DETAIL_WEAK_PTR_HPP
diff --git a/include/boost/asio/detail/win_event.hpp b/include/boost/asio/detail/win_event.hpp
index 7a7d54fac6..4c00068010 100644
--- a/include/boost/asio/detail/win_event.hpp
+++ b/include/boost/asio/detail/win_event.hpp
@@ -112,6 +112,27 @@ class win_event
     }
   }
 
+  // Timed wait for the event to become signalled.
+  template <typename Lock>
+  bool wait_for_usec(Lock& lock, long usec)
+  {
+    BOOST_ASIO_ASSERT(lock.locked());
+    if ((state_ & 1) == 0)
+    {
+      state_ += 2;
+      lock.unlock();
+      DWORD msec = usec > 0 ? (usec < 1000 ? 1 : usec / 1000) : 0;
+#if defined(BOOST_ASIO_WINDOWS_APP)
+      ::WaitForMultipleObjectsEx(2, events_, false, msec, false);
+#else // defined(BOOST_ASIO_WINDOWS_APP)
+      ::WaitForMultipleObjects(2, events_, false, msec);
+#endif // defined(BOOST_ASIO_WINDOWS_APP)
+      lock.lock();
+      state_ -= 2;
+    }
+    return (state_ & 1) != 0;
+  }
+
 private:
   HANDLE events_[2];
   std::size_t state_;
diff --git a/include/boost/asio/detail/win_fenced_block.hpp b/include/boost/asio/detail/win_fenced_block.hpp
index dba1d5355d..c6e5601361 100644
--- a/include/boost/asio/detail/win_fenced_block.hpp
+++ b/include/boost/asio/detail/win_fenced_block.hpp
@@ -20,6 +20,7 @@
 #if defined(BOOST_ASIO_WINDOWS) && !defined(UNDER_CE)
 
 #include <boost/asio/detail/socket_types.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
diff --git a/include/boost/asio/detail/win_global.hpp b/include/boost/asio/detail/win_global.hpp
new file mode 100644
index 0000000000..5a43902a7c
--- /dev/null
+++ b/include/boost/asio/detail/win_global.hpp
@@ -0,0 +1,75 @@
+//
+// detail/win_global.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_WIN_GLOBAL_HPP
+#define BOOST_ASIO_DETAIL_WIN_GLOBAL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/static_mutex.hpp>
+#include <boost/asio/detail/tss_ptr.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T>
+struct win_global_impl
+{
+  // Destructor automatically cleans up the global.
+  ~win_global_impl()
+  {
+    delete ptr_;
+  }
+
+  static win_global_impl instance_;
+  static static_mutex mutex_;
+  static T* ptr_;
+  static tss_ptr<T> tss_ptr_;
+};
+
+template <typename T>
+win_global_impl<T> win_global_impl<T>::instance_ = { 0 };
+
+template <typename T>
+static_mutex win_global_impl<T>::mutex_ = BOOST_ASIO_STATIC_MUTEX_INIT;
+
+template <typename T>
+T* win_global_impl<T>::ptr_ = 0;
+
+template <typename T>
+tss_ptr<T> win_global_impl<T>::tss_ptr_;
+
+template <typename T>
+T& win_global()
+{
+  if (static_cast<T*>(win_global_impl<T>::tss_ptr_) == 0)
+  {
+    win_global_impl<T>::mutex_.init();
+    static_mutex::scoped_lock lock(win_global_impl<T>::mutex_);
+    win_global_impl<T>::ptr_ = new T;
+    win_global_impl<T>::tss_ptr_ = win_global_impl<T>::ptr_;
+  }
+
+  return *win_global_impl<T>::tss_ptr_;
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_WIN_GLOBAL_HPP
diff --git a/include/boost/asio/detail/win_iocp_handle_read_op.hpp b/include/boost/asio/detail/win_iocp_handle_read_op.hpp
index fda3cc1e77..67d0ccc296 100644
--- a/include/boost/asio/detail/win_iocp_handle_read_op.hpp
+++ b/include/boost/asio/detail/win_iocp_handle_read_op.hpp
@@ -21,12 +21,12 @@
 #if defined(BOOST_ASIO_HAS_IOCP)
 
 #include <boost/asio/error.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -47,9 +47,10 @@ class win_iocp_handle_read_op : public operation
       buffers_(buffers),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t bytes_transferred)
   {
@@ -58,8 +59,9 @@ class win_iocp_handle_read_op : public operation
     // Take ownership of the operation object.
     win_iocp_handle_read_op* o(static_cast<win_iocp_handle_read_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     if (owner)
@@ -90,7 +92,7 @@ class win_iocp_handle_read_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_handle_service.hpp b/include/boost/asio/detail/win_iocp_handle_service.hpp
index 29f24f90c5..876fb68cb8 100644
--- a/include/boost/asio/detail/win_iocp_handle_service.hpp
+++ b/include/boost/asio/detail/win_iocp_handle_service.hpp
@@ -21,16 +21,16 @@
 #if defined(BOOST_ASIO_HAS_IOCP)
 
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/cstdint.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/operation.hpp>
 #include <boost/asio/detail/win_iocp_handle_read_op.hpp>
 #include <boost/asio/detail/win_iocp_handle_write_op.hpp>
-#include <boost/asio/detail/win_iocp_io_service.hpp>
+#include <boost/asio/detail/win_iocp_io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -38,7 +38,8 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-class win_iocp_handle_service
+class win_iocp_handle_service :
+  public service_base<win_iocp_handle_service>
 {
 public:
   // The native type of a stream handle.
@@ -75,10 +76,10 @@ class win_iocp_handle_service
     implementation_type* prev_;
   };
 
-  BOOST_ASIO_DECL win_iocp_handle_service(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL win_iocp_handle_service(boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Construct a new handle implementation.
   BOOST_ASIO_DECL void construct(implementation_type& impl);
@@ -149,11 +150,11 @@ class win_iocp_handle_service
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_handle_write_op<ConstBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "handle", &impl, "async_write_some"));
+    BOOST_ASIO_HANDLER_CREATION((iocp_service_.context(), *p.p, "handle", &impl,
+          reinterpret_cast<uintmax_t>(impl.handle_), "async_write_some"));
 
     start_write_op(impl, 0,
         buffer_sequence_adapter<boost::asio::const_buffer,
@@ -170,11 +171,11 @@ class win_iocp_handle_service
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_handle_write_op<ConstBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "handle", &impl, "async_write_some_at"));
+    BOOST_ASIO_HANDLER_CREATION((iocp_service_.context(), *p.p, "handle", &impl,
+          reinterpret_cast<uintmax_t>(impl.handle_), "async_write_some_at"));
 
     start_write_op(impl, offset,
         buffer_sequence_adapter<boost::asio::const_buffer,
@@ -211,11 +212,11 @@ class win_iocp_handle_service
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_handle_read_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "handle", &impl, "async_read_some"));
+    BOOST_ASIO_HANDLER_CREATION((iocp_service_.context(), *p.p, "handle", &impl,
+          reinterpret_cast<uintmax_t>(impl.handle_), "async_read_some"));
 
     start_read_op(impl, 0,
         buffer_sequence_adapter<boost::asio::mutable_buffer,
@@ -233,11 +234,11 @@ class win_iocp_handle_service
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_handle_read_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "handle", &impl, "async_read_some_at"));
+    BOOST_ASIO_HANDLER_CREATION((iocp_service_.context(), *p.p, "handle", &impl,
+          reinterpret_cast<uintmax_t>(impl.handle_), "async_read_some_at"));
 
     start_read_op(impl, offset,
         buffer_sequence_adapter<boost::asio::mutable_buffer,
@@ -300,7 +301,7 @@ class win_iocp_handle_service
 
   // The IOCP service used for running asynchronous operations and dispatching
   // handlers.
-  win_iocp_io_service& iocp_service_;
+  win_iocp_io_context& iocp_service_;
 
   // Mutex to protect access to the linked list of implementations.
   mutex mutex_;
diff --git a/include/boost/asio/detail/win_iocp_handle_write_op.hpp b/include/boost/asio/detail/win_iocp_handle_write_op.hpp
index a53db910a8..b6b1483265 100644
--- a/include/boost/asio/detail/win_iocp_handle_write_op.hpp
+++ b/include/boost/asio/detail/win_iocp_handle_write_op.hpp
@@ -21,12 +21,12 @@
 #if defined(BOOST_ASIO_HAS_IOCP)
 
 #include <boost/asio/error.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -46,16 +46,18 @@ class win_iocp_handle_write_op : public operation
       buffers_(buffers),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& ec, std::size_t bytes_transferred)
   {
     // Take ownership of the operation object.
     win_iocp_handle_write_op* o(static_cast<win_iocp_handle_write_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     if (owner)
@@ -82,7 +84,7 @@ class win_iocp_handle_write_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_io_service.hpp b/include/boost/asio/detail/win_iocp_io_context.hpp
similarity index 83%
rename from include/boost/asio/detail/win_iocp_io_service.hpp
rename to include/boost/asio/detail/win_iocp_io_context.hpp
index 0abb9fe89a..c53b9eb9c3 100644
--- a/include/boost/asio/detail/win_iocp_io_service.hpp
+++ b/include/boost/asio/detail/win_iocp_io_context.hpp
@@ -1,5 +1,5 @@
 //
-// detail/win_iocp_io_service.hpp
+// detail/win_iocp_io_context.hpp
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP
-#define BOOST_ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP
+#ifndef BOOST_ASIO_DETAIL_WIN_IOCP_IO_CONTEXT_HPP
+#define BOOST_ASIO_DETAIL_WIN_IOCP_IO_CONTEXT_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -19,19 +19,19 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/call_stack.hpp>
 #include <boost/asio/detail/limits.hpp>
 #include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/op_queue.hpp>
 #include <boost/asio/detail/scoped_ptr.hpp>
 #include <boost/asio/detail/socket_types.hpp>
 #include <boost/asio/detail/thread.hpp>
+#include <boost/asio/detail/thread_context.hpp>
 #include <boost/asio/detail/timer_queue_base.hpp>
 #include <boost/asio/detail/timer_queue_set.hpp>
 #include <boost/asio/detail/wait_op.hpp>
 #include <boost/asio/detail/win_iocp_operation.hpp>
 #include <boost/asio/detail/win_iocp_thread_info.hpp>
+#include <boost/asio/execution_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -41,18 +41,18 @@ namespace detail {
 
 class wait_op;
 
-class win_iocp_io_service
-  : public boost::asio::detail::service_base<win_iocp_io_service>
+class win_iocp_io_context
+  : public execution_context_service_base<win_iocp_io_context>,
+    public thread_context
 {
 public:
-
   // Constructor. Specifies a concurrency hint that is passed through to the
   // underlying I/O completion port.
-  BOOST_ASIO_DECL win_iocp_io_service(boost::asio::io_service& io_service,
-      size_t concurrency_hint = 0);
+  BOOST_ASIO_DECL win_iocp_io_context(boost::asio::execution_context& ctx,
+      int concurrency_hint = -1);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Initialise the task. Nothing to do here.
   void init_task()
@@ -69,6 +69,9 @@ class win_iocp_io_service
   // Run until stopped or one operation is performed.
   BOOST_ASIO_DECL size_t run_one(boost::system::error_code& ec);
 
+  // Run until timeout, interrupted, or one operation is performed.
+  BOOST_ASIO_DECL size_t wait_one(long usec, boost::system::error_code& ec);
+
   // Poll for operations without blocking.
   BOOST_ASIO_DECL size_t poll(boost::system::error_code& ec);
 
@@ -78,14 +81,14 @@ class win_iocp_io_service
   // Stop the event processing loop.
   BOOST_ASIO_DECL void stop();
 
-  // Determine whether the io_service is stopped.
+  // Determine whether the io_context is stopped.
   bool stopped() const
   {
     return ::InterlockedExchangeAdd(&stopped_, 0) != 0;
   }
 
-  // Reset in preparation for a subsequent run invocation.
-  void reset()
+  // Restart in preparation for a subsequent run invocation.
+  void restart()
   {
     ::InterlockedExchange(&stopped_, 0);
   }
@@ -109,14 +112,6 @@ class win_iocp_io_service
     return thread_call_stack::contains(this) != 0;
   }
 
-  // Request invocation of the given handler.
-  template <typename Handler>
-  void dispatch(Handler& handler);
-
-  // Request invocation of the given handler and return immediately.
-  template <typename Handler>
-  void post(Handler& handler);
-
   // Request invocation of the given operation and return immediately. Assumes
   // that work_started() has not yet been called for the operation.
   void post_immediate_completion(win_iocp_operation* op, bool)
@@ -150,8 +145,15 @@ class win_iocp_io_service
     post_deferred_completion(op);
   }
 
-  // Process unfinished operations as part of a shutdown_service operation.
-  // Assumes that work_started() was previously called for the operations.
+  // Enqueue the given operation following a failed attempt to dispatch the
+  // operation for immediate invocation.
+  void do_dispatch(operation* op)
+  {
+    post_immediate_completion(op, false);
+  }
+
+  // Process unfinished operations as part of a shutdown operation. Assumes
+  // that work_started() was previously called for the operations.
   BOOST_ASIO_DECL void abandon_operations(op_queue<operation>& ops);
 
   // Called after starting an overlapped I/O operation that did not complete
@@ -193,6 +195,18 @@ class win_iocp_io_service
       typename timer_queue<Time_Traits>::per_timer_data& timer,
       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
 
+  // Move the timer operations associated with the given timer.
+  template <typename Time_Traits>
+  void move_timer(timer_queue<Time_Traits>& queue,
+      typename timer_queue<Time_Traits>::per_timer_data& to,
+      typename timer_queue<Time_Traits>::per_timer_data& from);
+
+  // Get the concurrency hint that was used to initialise the io_context.
+  int concurrency_hint() const
+  {
+    return concurrency_hint_;
+  }
+
 private:
 #if defined(WINVER) && (WINVER < 0x0500)
   typedef DWORD dword_ptr_t;
@@ -205,7 +219,7 @@ class win_iocp_io_service
   // Dequeues at most one operation from the I/O completion port, and then
   // executes it. Returns the number of operations that were dequeued (i.e.
   // either 0 or 1).
-  BOOST_ASIO_DECL size_t do_one(bool block, boost::system::error_code& ec);
+  BOOST_ASIO_DECL size_t do_one(DWORD msec, boost::system::error_code& ec);
 
   // Helper to calculate the GetQueuedCompletionStatus timeout.
   BOOST_ASIO_DECL static DWORD get_gqcs_timeout();
@@ -296,9 +310,8 @@ class win_iocp_io_service
   // The operations that are ready to dispatch.
   op_queue<win_iocp_operation> completed_ops_;
 
-  // Per-thread call stack to track the state of each thread in the io_service.
-  typedef call_stack<win_iocp_io_service,
-      win_iocp_thread_info> thread_call_stack;
+  // The concurrency hint used to initialise the io_context.
+  const int concurrency_hint_;
 };
 
 } // namespace detail
@@ -307,11 +320,11 @@ class win_iocp_io_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#include <boost/asio/detail/impl/win_iocp_io_service.hpp>
+#include <boost/asio/detail/impl/win_iocp_io_context.hpp>
 #if defined(BOOST_ASIO_HEADER_ONLY)
-# include <boost/asio/detail/impl/win_iocp_io_service.ipp>
+# include <boost/asio/detail/impl/win_iocp_io_context.ipp>
 #endif // defined(BOOST_ASIO_HEADER_ONLY)
 
 #endif // defined(BOOST_ASIO_HAS_IOCP)
 
-#endif // BOOST_ASIO_DETAIL_WIN_IOCP_IO_SERVICE_HPP
+#endif // BOOST_ASIO_DETAIL_WIN_IOCP_IO_CONTEXT_HPP
diff --git a/include/boost/asio/detail/win_iocp_null_buffers_op.hpp b/include/boost/asio/detail/win_iocp_null_buffers_op.hpp
index 905d7a664e..318331a125 100644
--- a/include/boost/asio/detail/win_iocp_null_buffers_op.hpp
+++ b/include/boost/asio/detail/win_iocp_null_buffers_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/error.hpp>
@@ -48,14 +48,15 @@ class win_iocp_null_buffers_op : public reactor_op
       cancel_token_(cancel_token),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static bool do_perform(reactor_op*)
+  static status do_perform(reactor_op*)
   {
-    return true;
+    return done;
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t bytes_transferred)
   {
@@ -64,8 +65,9 @@ class win_iocp_null_buffers_op : public reactor_op
     // Take ownership of the operation object.
     win_iocp_null_buffers_op* o(static_cast<win_iocp_null_buffers_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // The reactor may have stored a result in the operation object.
     if (o->ec_)
@@ -100,7 +102,7 @@ class win_iocp_null_buffers_op : public reactor_op
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_operation.hpp b/include/boost/asio/detail/win_iocp_operation.hpp
index 232930344b..fcb79a933b 100644
--- a/include/boost/asio/detail/win_iocp_operation.hpp
+++ b/include/boost/asio/detail/win_iocp_operation.hpp
@@ -30,7 +30,7 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-class win_iocp_io_service;
+class win_iocp_io_context;
 
 // Base class for all operations. A function pointer is used instead of virtual
 // functions to avoid the associated overhead.
@@ -39,11 +39,12 @@ class win_iocp_operation
     BOOST_ASIO_ALSO_INHERIT_TRACKED_HANDLER
 {
 public:
-  void complete(win_iocp_io_service& owner,
-      const boost::system::error_code& ec,
+  typedef win_iocp_operation operation_type;
+
+  void complete(void* owner, const boost::system::error_code& ec,
       std::size_t bytes_transferred)
   {
-    func_(&owner, this, ec, bytes_transferred);
+    func_(owner, this, ec, bytes_transferred);
   }
 
   void destroy()
@@ -53,7 +54,7 @@ class win_iocp_operation
 
 protected:
   typedef void (*func_type)(
-      win_iocp_io_service*, win_iocp_operation*,
+      void*, win_iocp_operation*,
       const boost::system::error_code&, std::size_t);
 
   win_iocp_operation(func_type func)
@@ -80,7 +81,7 @@ class win_iocp_operation
 
 private:
   friend class op_queue_access;
-  friend class win_iocp_io_service;
+  friend class win_iocp_io_context;
   win_iocp_operation* next_;
   func_type func_;
   long ready_;
diff --git a/include/boost/asio/detail/win_iocp_overlapped_op.hpp b/include/boost/asio/detail/win_iocp_overlapped_op.hpp
index 6d0e4bfcc2..4b26db3f43 100644
--- a/include/boost/asio/detail/win_iocp_overlapped_op.hpp
+++ b/include/boost/asio/detail/win_iocp_overlapped_op.hpp
@@ -20,11 +20,11 @@
 #if defined(BOOST_ASIO_HAS_IOCP)
 
 #include <boost/asio/error.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -43,16 +43,18 @@ class win_iocp_overlapped_op : public operation
     : operation(&win_iocp_overlapped_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& ec, std::size_t bytes_transferred)
   {
     // Take ownership of the operation object.
     win_iocp_overlapped_op* o(static_cast<win_iocp_overlapped_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -70,7 +72,7 @@ class win_iocp_overlapped_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp b/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp
index 5d252c6fb1..fc51fd6c59 100644
--- a/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp
+++ b/include/boost/asio/detail/win_iocp_overlapped_ptr.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/win_iocp_overlapped_op.hpp>
-#include <boost/asio/detail/win_iocp_io_service.hpp>
+#include <boost/asio/detail/win_iocp_io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -47,11 +47,11 @@ class win_iocp_overlapped_ptr
   // Construct an win_iocp_overlapped_ptr to contain the specified handler.
   template <typename Handler>
   explicit win_iocp_overlapped_ptr(
-      boost::asio::io_service& io_service, BOOST_ASIO_MOVE_ARG(Handler) handler)
+      boost::asio::io_context& io_context, BOOST_ASIO_MOVE_ARG(Handler) handler)
     : ptr_(0),
       iocp_service_(0)
   {
-    this->reset(io_service, BOOST_ASIO_MOVE_CAST(Handler)(handler));
+    this->reset(io_context, BOOST_ASIO_MOVE_CAST(Handler)(handler));
   }
 
   // Destructor automatically frees the OVERLAPPED object unless released.
@@ -75,22 +75,21 @@ class win_iocp_overlapped_ptr
   // Reset to contain the specified handler, freeing any current OVERLAPPED
   // object.
   template <typename Handler>
-  void reset(boost::asio::io_service& io_service, Handler handler)
+  void reset(boost::asio::io_context& io_context, Handler handler)
   {
     typedef win_iocp_overlapped_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "io_service",
-          &io_service.impl_, "overlapped"));
+    BOOST_ASIO_HANDLER_CREATION((io_context, *p.p,
+          "io_context", &io_context.impl_, 0, "overlapped"));
 
-    io_service.impl_.work_started();
+    io_context.impl_.work_started();
     reset();
     ptr_ = p.p;
     p.v = p.p = 0;
-    iocp_service_ = &io_service.impl_;
+    iocp_service_ = &io_context.impl_;
   }
 
   // Get the contained OVERLAPPED object.
@@ -132,7 +131,7 @@ class win_iocp_overlapped_ptr
 
 private:
   win_iocp_operation* ptr_;
-  win_iocp_io_service* iocp_service_;
+  win_iocp_io_context* iocp_service_;
 };
 
 } // namespace detail
diff --git a/include/boost/asio/detail/win_iocp_serial_port_service.hpp b/include/boost/asio/detail/win_iocp_serial_port_service.hpp
index 6b21f96535..4b641f0c73 100644
--- a/include/boost/asio/detail/win_iocp_serial_port_service.hpp
+++ b/include/boost/asio/detail/win_iocp_serial_port_service.hpp
@@ -22,7 +22,7 @@
 
 #include <string>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/win_iocp_handle_service.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -32,7 +32,8 @@ namespace asio {
 namespace detail {
 
 // Extend win_iocp_handle_service to provide serial port support.
-class win_iocp_serial_port_service
+class win_iocp_serial_port_service :
+  public service_base<win_iocp_serial_port_service>
 {
 public:
   // The native type of a serial port.
@@ -43,10 +44,10 @@ class win_iocp_serial_port_service
 
   // Constructor.
   BOOST_ASIO_DECL win_iocp_serial_port_service(
-      boost::asio::io_service& io_service);
+      boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Construct a new serial port implementation.
   void construct(implementation_type& impl)
@@ -185,8 +186,8 @@ class win_iocp_serial_port_service
   static boost::system::error_code store_option(const void* option,
       ::DCB& storage, boost::system::error_code& ec)
   {
-    return static_cast<const SettableSerialPortOption*>(option)->store(
-        storage, ec);
+    static_cast<const SettableSerialPortOption*>(option)->store(storage, ec);
+    return ec;
   }
 
   // Helper function to set a serial port option.
@@ -203,7 +204,8 @@ class win_iocp_serial_port_service
   static boost::system::error_code load_option(void* option,
       const ::DCB& storage, boost::system::error_code& ec)
   {
-    return static_cast<GettableSerialPortOption*>(option)->load(storage, ec);
+    static_cast<GettableSerialPortOption*>(option)->load(storage, ec);
+    return ec;
   }
 
   // Helper function to get a serial port option.
diff --git a/include/boost/asio/detail/win_iocp_socket_accept_op.hpp b/include/boost/asio/detail/win_iocp_socket_accept_op.hpp
index d296103c54..f05be5465d 100644
--- a/include/boost/asio/detail/win_iocp_socket_accept_op.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_accept_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/detail/win_iocp_socket_service_base.hpp>
@@ -55,6 +55,7 @@ class win_iocp_socket_accept_op : public operation
       enable_connection_aborted_(enable_connection_aborted),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
   socket_holder& new_socket()
@@ -72,7 +73,7 @@ class win_iocp_socket_accept_op : public operation
     return sizeof(sockaddr_storage_type) + 16;
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t /*bytes_transferred*/)
   {
@@ -81,6 +82,7 @@ class win_iocp_socket_accept_op : public operation
     // Take ownership of the operation object.
     win_iocp_socket_accept_op* o(static_cast<win_iocp_socket_accept_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
     if (owner)
     {
@@ -121,7 +123,7 @@ class win_iocp_socket_accept_op : public operation
         *o->peer_endpoint_ = peer_endpoint;
     }
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -139,7 +141,7 @@ class win_iocp_socket_accept_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
@@ -156,6 +158,136 @@ class win_iocp_socket_accept_op : public operation
   Handler handler_;
 };
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+
+template <typename Protocol, typename Handler>
+class win_iocp_socket_move_accept_op : public operation
+{
+public:
+  BOOST_ASIO_DEFINE_HANDLER_PTR(win_iocp_socket_move_accept_op);
+
+  win_iocp_socket_move_accept_op(
+      win_iocp_socket_service_base& socket_service, socket_type socket,
+      const Protocol& protocol, boost::asio::io_context& peer_io_context,
+      typename Protocol::endpoint* peer_endpoint,
+      bool enable_connection_aborted, Handler& handler)
+    : operation(&win_iocp_socket_move_accept_op::do_complete),
+      socket_service_(socket_service),
+      socket_(socket),
+      peer_(peer_io_context),
+      protocol_(protocol),
+      peer_endpoint_(peer_endpoint),
+      enable_connection_aborted_(enable_connection_aborted),
+      handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
+  {
+    handler_work<Handler>::start(handler_);
+  }
+
+  socket_holder& new_socket()
+  {
+    return new_socket_;
+  }
+
+  void* output_buffer()
+  {
+    return output_buffer_;
+  }
+
+  DWORD address_length()
+  {
+    return sizeof(sockaddr_storage_type) + 16;
+  }
+
+  static void do_complete(void* owner, operation* base,
+      const boost::system::error_code& result_ec,
+      std::size_t /*bytes_transferred*/)
+  {
+    boost::system::error_code ec(result_ec);
+
+    // Take ownership of the operation object.
+    win_iocp_socket_move_accept_op* o(
+        static_cast<win_iocp_socket_move_accept_op*>(base));
+    ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
+
+    if (owner)
+    {
+      typename Protocol::endpoint peer_endpoint;
+      std::size_t addr_len = peer_endpoint.capacity();
+      socket_ops::complete_iocp_accept(o->socket_,
+          o->output_buffer(), o->address_length(),
+          peer_endpoint.data(), &addr_len,
+          o->new_socket_.get(), ec);
+
+      // Restart the accept operation if we got the connection_aborted error
+      // and the enable_connection_aborted socket option is not set.
+      if (ec == boost::asio::error::connection_aborted
+          && !o->enable_connection_aborted_)
+      {
+        o->reset();
+        o->socket_service_.restart_accept_op(o->socket_,
+            o->new_socket_, o->protocol_.family(),
+            o->protocol_.type(), o->protocol_.protocol(),
+            o->output_buffer(), o->address_length(), o);
+        p.v = p.p = 0;
+        return;
+      }
+
+      // If the socket was successfully accepted, transfer ownership of the
+      // socket to the peer object.
+      if (!ec)
+      {
+        o->peer_.assign(o->protocol_,
+            typename Protocol::socket::native_handle_type(
+              o->new_socket_.get(), peer_endpoint), ec);
+        if (!ec)
+          o->new_socket_.release();
+      }
+
+      // Pass endpoint back to caller.
+      if (o->peer_endpoint_)
+        *o->peer_endpoint_ = peer_endpoint;
+    }
+
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
+
+    // Make a copy of the handler so that the memory can be deallocated before
+    // the upcall is made. Even if we're not about to make an upcall, a
+    // sub-object of the handler may be the true owner of the memory associated
+    // with the handler. Consequently, a local copy of the handler is required
+    // to ensure that any owning sub-object remains valid until after we have
+    // deallocated the memory here.
+    detail::move_binder2<Handler,
+      boost::system::error_code, typename Protocol::socket>
+        handler(0, BOOST_ASIO_MOVE_CAST(Handler)(o->handler_), ec,
+          BOOST_ASIO_MOVE_CAST(typename Protocol::socket)(o->peer_));
+    p.h = boost::asio::detail::addressof(handler.handler_);
+    p.reset();
+
+    // Make the upcall if required.
+    if (owner)
+    {
+      fenced_block b(fenced_block::half);
+      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
+      w.complete(handler, handler.handler_);
+      BOOST_ASIO_HANDLER_INVOCATION_END;
+    }
+  }
+
+private:
+  win_iocp_socket_service_base& socket_service_;
+  socket_type socket_;
+  socket_holder new_socket_;
+  typename Protocol::socket peer_;
+  Protocol protocol_;
+  typename Protocol::endpoint* peer_endpoint_;
+  unsigned char output_buffer_[(sizeof(sockaddr_storage_type) + 16) * 2];
+  bool enable_connection_aborted_;
+  Handler handler_;
+};
+
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
 } // namespace detail
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/detail/win_iocp_socket_connect_op.hpp b/include/boost/asio/detail/win_iocp_socket_connect_op.hpp
index e987c6b6c4..829597ae9c 100644
--- a/include/boost/asio/detail/win_iocp_socket_connect_op.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_connect_op.hpp
@@ -19,11 +19,11 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/error.hpp>
@@ -44,12 +44,13 @@ class win_iocp_socket_connect_op_base : public reactor_op
   {
   }
 
-  static bool do_perform(reactor_op* base)
+  static status do_perform(reactor_op* base)
   {
     win_iocp_socket_connect_op_base* o(
         static_cast<win_iocp_socket_connect_op_base*>(base));
 
-    return socket_ops::non_blocking_connect(o->socket_, o->ec_);
+    return socket_ops::non_blocking_connect(
+        o->socket_, o->ec_) ? done : not_done;
   }
 
   socket_type socket_;
@@ -67,9 +68,10 @@ class win_iocp_socket_connect_op : public win_iocp_socket_connect_op_base
         &win_iocp_socket_connect_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t /*bytes_transferred*/)
   {
@@ -79,6 +81,7 @@ class win_iocp_socket_connect_op : public win_iocp_socket_connect_op_base
     win_iocp_socket_connect_op* o(
         static_cast<win_iocp_socket_connect_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
     if (owner)
     {
@@ -88,7 +91,7 @@ class win_iocp_socket_connect_op : public win_iocp_socket_connect_op_base
         ec = o->ec_;
     }
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -106,7 +109,7 @@ class win_iocp_socket_connect_op : public win_iocp_socket_connect_op_base
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_socket_recv_op.hpp b/include/boost/asio/detail/win_iocp_socket_recv_op.hpp
index 4202822d17..46f5dcd3f5 100644
--- a/include/boost/asio/detail/win_iocp_socket_recv_op.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_recv_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/error.hpp>
@@ -50,9 +50,10 @@ class win_iocp_socket_recv_op : public operation
       buffers_(buffers),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t bytes_transferred)
   {
@@ -61,8 +62,9 @@ class win_iocp_socket_recv_op : public operation
     // Take ownership of the operation object.
     win_iocp_socket_recv_op* o(static_cast<win_iocp_socket_recv_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     // Check whether buffers are still valid.
@@ -94,7 +96,7 @@ class win_iocp_socket_recv_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_socket_recvfrom_op.hpp b/include/boost/asio/detail/win_iocp_socket_recvfrom_op.hpp
index 21ca4fb331..b9437c3a60 100644
--- a/include/boost/asio/detail/win_iocp_socket_recvfrom_op.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_recvfrom_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/error.hpp>
@@ -51,6 +51,7 @@ class win_iocp_socket_recvfrom_op : public operation
       buffers_(buffers),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
   int& endpoint_size()
@@ -58,7 +59,7 @@ class win_iocp_socket_recvfrom_op : public operation
     return endpoint_size_;
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t bytes_transferred)
   {
@@ -68,8 +69,9 @@ class win_iocp_socket_recvfrom_op : public operation
     win_iocp_socket_recvfrom_op* o(
         static_cast<win_iocp_socket_recvfrom_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     // Check whether buffers are still valid.
@@ -101,7 +103,7 @@ class win_iocp_socket_recvfrom_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_socket_recvmsg_op.hpp b/include/boost/asio/detail/win_iocp_socket_recvmsg_op.hpp
index 5179bb2945..51747c55e8 100644
--- a/include/boost/asio/detail/win_iocp_socket_recvmsg_op.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_recvmsg_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/error.hpp>
@@ -52,9 +52,10 @@ class win_iocp_socket_recvmsg_op : public operation
       out_flags_(out_flags),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t bytes_transferred)
   {
@@ -64,8 +65,9 @@ class win_iocp_socket_recvmsg_op : public operation
     win_iocp_socket_recvmsg_op* o(
         static_cast<win_iocp_socket_recvmsg_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     // Check whether buffers are still valid.
@@ -95,7 +97,7 @@ class win_iocp_socket_recvmsg_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_socket_send_op.hpp b/include/boost/asio/detail/win_iocp_socket_send_op.hpp
index c9abc0e664..48951c2508 100644
--- a/include/boost/asio/detail/win_iocp_socket_send_op.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_send_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/operation.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/error.hpp>
@@ -48,9 +48,10 @@ class win_iocp_socket_send_op : public operation
       buffers_(buffers),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code& result_ec,
       std::size_t bytes_transferred)
   {
@@ -59,8 +60,9 @@ class win_iocp_socket_send_op : public operation
     // Take ownership of the operation object.
     win_iocp_socket_send_op* o(static_cast<win_iocp_socket_send_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     // Check whether buffers are still valid.
@@ -89,7 +91,7 @@ class win_iocp_socket_send_op : public operation
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/win_iocp_socket_service.hpp b/include/boost/asio/detail/win_iocp_socket_service.hpp
index 179798c8d9..ed1cd1edd5 100644
--- a/include/boost/asio/detail/win_iocp_socket_service.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_service.hpp
@@ -21,22 +21,22 @@
 
 #include <cstring>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/socket_base.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/operation.hpp>
-#include <boost/asio/detail/reactor.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
+#include <boost/asio/detail/select_reactor.hpp>
 #include <boost/asio/detail/socket_holder.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/detail/socket_types.hpp>
-#include <boost/asio/detail/win_iocp_io_service.hpp>
+#include <boost/asio/detail/win_iocp_io_context.hpp>
 #include <boost/asio/detail/win_iocp_null_buffers_op.hpp>
 #include <boost/asio/detail/win_iocp_socket_accept_op.hpp>
 #include <boost/asio/detail/win_iocp_socket_connect_op.hpp>
@@ -51,7 +51,9 @@ namespace asio {
 namespace detail {
 
 template <typename Protocol>
-class win_iocp_socket_service : public win_iocp_socket_service_base
+class win_iocp_socket_service :
+  public service_base<win_iocp_socket_service<Protocol> >,
+  public win_iocp_socket_service_base
 {
 public:
   // The protocol type.
@@ -128,11 +130,18 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
   };
 
   // Constructor.
-  win_iocp_socket_service(boost::asio::io_service& io_service)
-    : win_iocp_socket_service_base(io_service)
+  win_iocp_socket_service(boost::asio::io_context& io_context)
+    : service_base<win_iocp_socket_service<Protocol> >(io_context),
+      win_iocp_socket_service_base(io_context)
   {
   }
 
+  // Destroy all user-defined handler objects owned by the service.
+  void shutdown()
+  {
+    this->base_shutdown();
+  }
+
   // Move-construct a new socket implementation.
   void move_construct(implementation_type& impl,
       implementation_type& other_impl)
@@ -279,6 +288,14 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     return endpoint;
   }
 
+  // Disable sends or receives on the socket.
+  boost::system::error_code shutdown(base_implementation_type& impl,
+      socket_base::shutdown_type what, boost::system::error_code& ec)
+  {
+    socket_ops::shutdown(impl.socket_, what, ec);
+    return ec;
+  }
+
   // Send a datagram to the specified endpoint. Returns the number of bytes
   // sent.
   template <typename ConstBufferSequence>
@@ -300,7 +317,7 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
       boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_write(impl.socket_, impl.state_, ec);
+    socket_ops::poll_write(impl.socket_, impl.state_, -1, ec);
 
     return 0;
   }
@@ -315,11 +332,11 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_socket_send_op<ConstBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_send_to"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_send_to"));
 
     buffer_sequence_adapter<boost::asio::const_buffer,
         ConstBufferSequence> bufs(buffers);
@@ -338,14 +355,13 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_send_to(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_send_to(null_buffers)"));
 
-    start_reactor_op(impl, reactor::write_op, p.p);
+    start_reactor_op(impl, select_reactor::write_op, p.p);
     p.v = p.p = 0;
   }
 
@@ -377,7 +393,7 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
       socket_base::message_flags, boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_read(impl.socket_, impl.state_, ec);
+    socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
 
     // Reset endpoint since it can be given no sensible value at this time.
     sender_endpoint = endpoint_type();
@@ -397,11 +413,11 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     typedef win_iocp_socket_recvfrom_op<
       MutableBufferSequence, endpoint_type, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(sender_endp, impl.cancel_token_, buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_receive_from"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_receive_from"));
 
     buffer_sequence_adapter<boost::asio::mutable_buffer,
         MutableBufferSequence> bufs(buffers);
@@ -420,12 +436,11 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl,
-          "async_receive_from(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_receive_from(null_buffers)"));
 
     // Reset endpoint since it can be given no sensible value at this time.
     sender_endpoint = endpoint_type();
@@ -456,13 +471,42 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     {
       if (peer_endpoint)
         peer_endpoint->resize(addr_len);
-      if (!peer.assign(impl.protocol_, new_socket.get(), ec))
+      peer.assign(impl.protocol_, new_socket.get(), ec);
+      if (!ec)
         new_socket.release();
     }
 
     return ec;
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+  // Accept a new connection.
+  typename Protocol::socket accept(implementation_type& impl,
+      io_context* peer_io_context, endpoint_type* peer_endpoint,
+      boost::system::error_code& ec)
+  {
+    typename Protocol::socket peer(
+        peer_io_context ? *peer_io_context : io_context_);
+
+    std::size_t addr_len = peer_endpoint ? peer_endpoint->capacity() : 0;
+    socket_holder new_socket(socket_ops::sync_accept(impl.socket_,
+          impl.state_, peer_endpoint ? peer_endpoint->data() : 0,
+          peer_endpoint ? &addr_len : 0, ec));
+
+    // On success, assign new connection to peer socket object.
+    if (new_socket.get() != invalid_socket)
+    {
+      if (peer_endpoint)
+        peer_endpoint->resize(addr_len);
+      peer.assign(impl.protocol_, new_socket.get(), ec);
+      if (!ec)
+        new_socket.release();
+    }
+
+    return peer;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
   // Start an asynchronous accept. The peer and peer_endpoint objects
   // must be valid until the accept's handler is invoked.
   template <typename Socket, typename Handler>
@@ -472,14 +516,14 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_socket_accept_op<Socket, protocol_type, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     bool enable_connection_aborted =
       (impl.state_ & socket_ops::enable_connection_aborted) != 0;
     p.p = new (p.v) op(*this, impl.socket_, peer, impl.protocol_,
         peer_endpoint, enable_connection_aborted, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_accept"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_accept"));
 
     start_accept_op(impl, peer.is_open(), p.p->new_socket(),
         impl.protocol_.family(), impl.protocol_.type(),
@@ -488,6 +532,35 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     p.v = p.p = 0;
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+  // Start an asynchronous accept. The peer and peer_endpoint objects
+  // must be valid until the accept's handler is invoked.
+  template <typename Handler>
+  void async_accept(implementation_type& impl,
+      boost::asio::io_context* peer_io_context,
+      endpoint_type* peer_endpoint, Handler& handler)
+  {
+    // Allocate and construct an operation to wrap the handler.
+    typedef win_iocp_socket_move_accept_op<protocol_type, Handler> op;
+    typename op::ptr p = { boost::asio::detail::addressof(handler),
+      op::ptr::allocate(handler), 0 };
+    bool enable_connection_aborted =
+      (impl.state_ & socket_ops::enable_connection_aborted) != 0;
+    p.p = new (p.v) op(*this, impl.socket_, impl.protocol_,
+        peer_io_context ? *peer_io_context : io_context_,
+        peer_endpoint, enable_connection_aborted, handler);
+
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_accept"));
+
+    start_accept_op(impl, false, p.p->new_socket(),
+        impl.protocol_.family(), impl.protocol_.type(),
+        impl.protocol_.protocol(), p.p->output_buffer(),
+        p.p->address_length(), p.p);
+    p.v = p.p = 0;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
   // Connect the socket to the specified endpoint.
   boost::system::error_code connect(implementation_type& impl,
       const endpoint_type& peer_endpoint, boost::system::error_code& ec)
@@ -505,11 +578,11 @@ class win_iocp_socket_service : public win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_socket_connect_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.socket_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_connect"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_connect"));
 
     start_connect_op(impl, impl.protocol_.family(), impl.protocol_.type(),
         peer_endpoint.data(), static_cast<int>(peer_endpoint.size()), p.p);
diff --git a/include/boost/asio/detail/win_iocp_socket_service_base.hpp b/include/boost/asio/detail/win_iocp_socket_service_base.hpp
index 8ecf219598..2af1546712 100644
--- a/include/boost/asio/detail/win_iocp_socket_service_base.hpp
+++ b/include/boost/asio/detail/win_iocp_socket_service_base.hpp
@@ -20,27 +20,28 @@
 #if defined(BOOST_ASIO_HAS_IOCP)
 
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/socket_base.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/mutex.hpp>
 #include <boost/asio/detail/operation.hpp>
-#include <boost/asio/detail/reactor.hpp>
 #include <boost/asio/detail/reactor_op.hpp>
+#include <boost/asio/detail/select_reactor.hpp>
 #include <boost/asio/detail/socket_holder.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/detail/socket_types.hpp>
-#include <boost/asio/detail/win_iocp_io_service.hpp>
+#include <boost/asio/detail/win_iocp_io_context.hpp>
 #include <boost/asio/detail/win_iocp_null_buffers_op.hpp>
 #include <boost/asio/detail/win_iocp_socket_connect_op.hpp>
 #include <boost/asio/detail/win_iocp_socket_send_op.hpp>
 #include <boost/asio/detail/win_iocp_socket_recv_op.hpp>
 #include <boost/asio/detail/win_iocp_socket_recvmsg_op.hpp>
+#include <boost/asio/detail/win_iocp_wait_op.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -69,7 +70,7 @@ class win_iocp_socket_service_base
     socket_ops::shared_cancel_token_type cancel_token_;
 
     // Per-descriptor data used by the reactor.
-    reactor::per_descriptor_data reactor_data_;
+    select_reactor::per_descriptor_data reactor_data_;
 
 #if defined(BOOST_ASIO_ENABLE_CANCELIO)
     // The ID of the thread from which it is safe to cancel asynchronous
@@ -86,10 +87,10 @@ class win_iocp_socket_service_base
 
   // Constructor.
   BOOST_ASIO_DECL win_iocp_socket_service_base(
-      boost::asio::io_service& io_service);
+      boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void base_shutdown();
 
   // Construct a new socket implementation.
   BOOST_ASIO_DECL void construct(base_implementation_type& impl);
@@ -116,6 +117,10 @@ class win_iocp_socket_service_base
   BOOST_ASIO_DECL boost::system::error_code close(
       base_implementation_type& impl, boost::system::error_code& ec);
 
+  // Release ownership of the socket.
+  BOOST_ASIO_DECL socket_type release(
+      base_implementation_type& impl, boost::system::error_code& ec);
+
   // Cancel all operations associated with the socket.
   BOOST_ASIO_DECL boost::system::error_code cancel(
       base_implementation_type& impl, boost::system::error_code& ec);
@@ -180,14 +185,68 @@ class win_iocp_socket_service_base
     return ec;
   }
 
-  // Disable sends or receives on the socket.
-  boost::system::error_code shutdown(base_implementation_type& impl,
-      socket_base::shutdown_type what, boost::system::error_code& ec)
+  // Wait for the socket to become ready to read, ready to write, or to have
+  // pending error conditions.
+  boost::system::error_code wait(base_implementation_type& impl,
+      socket_base::wait_type w, boost::system::error_code& ec)
   {
-    socket_ops::shutdown(impl.socket_, what, ec);
+    switch (w)
+    {
+    case socket_base::wait_read:
+      socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
+      break;
+    case socket_base::wait_write:
+      socket_ops::poll_write(impl.socket_, impl.state_, -1, ec);
+      break;
+    case socket_base::wait_error:
+      socket_ops::poll_error(impl.socket_, impl.state_, -1, ec);
+      break;
+    default:
+      ec = boost::asio::error::invalid_argument;
+      break;
+    }
+
     return ec;
   }
 
+  // Asynchronously wait for the socket to become ready to read, ready to
+  // write, or to have pending error conditions.
+  template <typename Handler>
+  void async_wait(base_implementation_type& impl,
+      socket_base::wait_type w, Handler& handler)
+  {
+    bool is_continuation =
+      boost_asio_handler_cont_helpers::is_continuation(handler);
+
+    // Allocate and construct an operation to wrap the handler.
+    typedef win_iocp_wait_op<Handler> op;
+    typename op::ptr p = { boost::asio::detail::addressof(handler),
+      op::ptr::allocate(handler), 0 };
+    p.p = new (p.v) op(impl.cancel_token_, handler);
+
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_wait"));
+
+    switch (w)
+    {
+      case socket_base::wait_read:
+        start_null_buffers_receive_op(impl, 0, p.p);
+        break;
+      case socket_base::wait_write:
+        start_reactor_op(impl, select_reactor::write_op, p.p);
+        break;
+      case socket_base::wait_error:
+        start_reactor_op(impl, select_reactor::except_op, p.p);
+        break;
+      default:
+        p.p->ec_ = boost::asio::error::invalid_argument;
+        iocp_service_.post_immediate_completion(p.p, is_continuation);
+        break;
+    }
+
+    p.v = p.p = 0;
+  }
+
   // Send the given data to the peer. Returns the number of bytes sent.
   template <typename ConstBufferSequence>
   size_t send(base_implementation_type& impl,
@@ -206,7 +265,7 @@ class win_iocp_socket_service_base
       socket_base::message_flags, boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_write(impl.socket_, impl.state_, ec);
+    socket_ops::poll_write(impl.socket_, impl.state_, -1, ec);
 
     return 0;
   }
@@ -221,11 +280,11 @@ class win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_socket_send_op<ConstBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_send"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_send"));
 
     buffer_sequence_adapter<boost::asio::const_buffer,
         ConstBufferSequence> bufs(buffers);
@@ -244,14 +303,13 @@ class win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_send(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_send(null_buffers)"));
 
-    start_reactor_op(impl, reactor::write_op, p.p);
+    start_reactor_op(impl, select_reactor::write_op, p.p);
     p.v = p.p = 0;
   }
 
@@ -273,7 +331,7 @@ class win_iocp_socket_service_base
       socket_base::message_flags, boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_read(impl.socket_, impl.state_, ec);
+    socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
 
     return 0;
   }
@@ -288,11 +346,11 @@ class win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_socket_recv_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.state_, impl.cancel_token_, buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_receive"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_receive"));
 
     buffer_sequence_adapter<boost::asio::mutable_buffer,
         MutableBufferSequence> bufs(buffers);
@@ -311,12 +369,11 @@ class win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_receive(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_receive(null_buffers)"));
 
     start_null_buffers_receive_op(impl, flags, p.p);
     p.v = p.p = 0;
@@ -343,7 +400,7 @@ class win_iocp_socket_service_base
       socket_base::message_flags& out_flags, boost::system::error_code& ec)
   {
     // Wait for socket to become ready.
-    socket_ops::poll_read(impl.socket_, impl.state_, ec);
+    socket_ops::poll_read(impl.socket_, impl.state_, -1, ec);
 
     // Clear out_flags, since we cannot give it any other sensible value when
     // performing a null_buffers operation.
@@ -362,12 +419,11 @@ class win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_socket_recvmsg_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, buffers, out_flags, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket",
-          &impl, "async_receive_with_flags"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_receive_with_flags"));
 
     buffer_sequence_adapter<boost::asio::mutable_buffer,
         MutableBufferSequence> bufs(buffers);
@@ -385,12 +441,11 @@ class win_iocp_socket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef win_iocp_null_buffers_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(impl.cancel_token_, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl,
-          "async_receive_with_flags(null_buffers)"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_, *p.p, "socket",
+          &impl, impl.socket_, "async_receive_with_flags(null_buffers)"));
 
     // Reset out_flags since it can be given no sensible value at this time.
     out_flags = 0;
@@ -464,9 +519,9 @@ class win_iocp_socket_service_base
       base_implementation_type& impl);
 
   // Helper function to get the reactor. If no reactor has been created yet, a
-  // new one is obtained from the io_service and a pointer to it is cached in
+  // new one is obtained from the io_context and a pointer to it is cached in
   // this service.
-  BOOST_ASIO_DECL reactor& get_reactor();
+  BOOST_ASIO_DECL select_reactor& get_reactor();
 
   // The type of a ConnectEx function pointer, as old SDKs may not provide it.
   typedef BOOL (PASCAL *connect_ex_fn)(SOCKET,
@@ -478,6 +533,15 @@ class win_iocp_socket_service_base
   BOOST_ASIO_DECL connect_ex_fn get_connect_ex(
       base_implementation_type& impl, int type);
 
+  // The type of a NtSetInformationFile function pointer.
+  typedef LONG (NTAPI *nt_set_info_fn)(HANDLE, ULONG_PTR*, void*, ULONG, ULONG);
+
+  // Helper function to get the NtSetInformationFile function pointer. If no
+  // NtSetInformationFile pointer has been obtained yet, one is obtained using
+  // GetProcAddress and the pointer is cached. Returns a null pointer if
+  // NtSetInformationFile is not available.
+  BOOST_ASIO_DECL nt_set_info_fn get_nt_set_info();
+
   // Helper function to emulate InterlockedCompareExchangePointer functionality
   // for:
   // - very old Platform SDKs; and
@@ -490,20 +554,23 @@ class win_iocp_socket_service_base
   // - platform SDKs where MSVC's /Wp64 option causes spurious warnings.
   BOOST_ASIO_DECL void* interlocked_exchange_pointer(void** dest, void* val);
 
-  // The io_service used to obtain the reactor, if required.
-  boost::asio::io_service& io_service_;
+  // The io_context used to obtain the reactor, if required.
+  boost::asio::io_context& io_context_;
 
   // The IOCP service used for running asynchronous operations and dispatching
   // handlers.
-  win_iocp_io_service& iocp_service_;
+  win_iocp_io_context& iocp_service_;
 
   // The reactor used for performing connect operations. This object is created
   // only if needed.
-  reactor* reactor_;
+  select_reactor* reactor_;
 
   // Pointer to ConnectEx implementation.
   void* connect_ex_;
 
+  // Pointer to NtSetInformationFile implementation.
+  void* nt_set_info_;
+
   // Mutex to protect access to the linked list of implementations. 
   boost::asio::detail::mutex mutex_;
 
diff --git a/include/boost/asio/detail/win_iocp_wait_op.hpp b/include/boost/asio/detail/win_iocp_wait_op.hpp
new file mode 100644
index 0000000000..c5bc4a273f
--- /dev/null
+++ b/include/boost/asio/detail/win_iocp_wait_op.hpp
@@ -0,0 +1,123 @@
+//
+// detail/win_iocp_wait_op.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_WIN_IOCP_WAIT_OP_HPP
+#define BOOST_ASIO_DETAIL_WIN_IOCP_WAIT_OP_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_IOCP)
+
+#include <boost/asio/detail/bind_handler.hpp>
+#include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/reactor_op.hpp>
+#include <boost/asio/detail/socket_ops.hpp>
+#include <boost/asio/error.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Handler>
+class win_iocp_wait_op : public reactor_op
+{
+public:
+  BOOST_ASIO_DEFINE_HANDLER_PTR(win_iocp_wait_op);
+
+  win_iocp_wait_op(socket_ops::weak_cancel_token_type cancel_token,
+      Handler& handler)
+    : reactor_op(&win_iocp_wait_op::do_perform,
+        &win_iocp_wait_op::do_complete),
+      cancel_token_(cancel_token),
+      handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
+  {
+    handler_work<Handler>::start(handler_);
+  }
+
+  static status do_perform(reactor_op*)
+  {
+    return done;
+  }
+
+  static void do_complete(void* owner, operation* base,
+      const boost::system::error_code& result_ec,
+      std::size_t /*bytes_transferred*/)
+  {
+    boost::system::error_code ec(result_ec);
+
+    // Take ownership of the operation object.
+    win_iocp_wait_op* o(static_cast<win_iocp_wait_op*>(base));
+    ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
+
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
+
+    // The reactor may have stored a result in the operation object.
+    if (o->ec_)
+      ec = o->ec_;
+
+    // Map non-portable errors to their portable counterparts.
+    if (ec.value() == ERROR_NETNAME_DELETED)
+    {
+      if (o->cancel_token_.expired())
+        ec = boost::asio::error::operation_aborted;
+      else
+        ec = boost::asio::error::connection_reset;
+    }
+    else if (ec.value() == ERROR_PORT_UNREACHABLE)
+    {
+      ec = boost::asio::error::connection_refused;
+    }
+
+    // Make a copy of the handler so that the memory can be deallocated before
+    // the upcall is made. Even if we're not about to make an upcall, a
+    // sub-object of the handler may be the true owner of the memory associated
+    // with the handler. Consequently, a local copy of the handler is required
+    // to ensure that any owning sub-object remains valid until after we have
+    // deallocated the memory here.
+    detail::binder1<Handler, boost::system::error_code>
+      handler(o->handler_, ec);
+    p.h = boost::asio::detail::addressof(handler.handler_);
+    p.reset();
+
+    // Make the upcall if required.
+    if (owner)
+    {
+      fenced_block b(fenced_block::half);
+      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
+      w.complete(handler, handler.handler_);
+      BOOST_ASIO_HANDLER_INVOCATION_END;
+    }
+  }
+
+private:
+  socket_ops::weak_cancel_token_type cancel_token_;
+  Handler handler_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // defined(BOOST_ASIO_HAS_IOCP)
+
+#endif // BOOST_ASIO_DETAIL_WIN_IOCP_WAIT_OP_HPP
diff --git a/include/boost/asio/detail/win_object_handle_service.hpp b/include/boost/asio/detail/win_object_handle_service.hpp
index 3383657304..1e94a304eb 100644
--- a/include/boost/asio/detail/win_object_handle_service.hpp
+++ b/include/boost/asio/detail/win_object_handle_service.hpp
@@ -20,11 +20,11 @@
 
 #if defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/wait_handler.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -32,7 +32,8 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-class win_object_handle_service
+class win_object_handle_service :
+  public service_base<win_object_handle_service>
 {
 public:
   // The native type of an object handle.
@@ -80,10 +81,10 @@ class win_object_handle_service
 
   // Constructor.
   BOOST_ASIO_DECL win_object_handle_service(
-      boost::asio::io_service& io_service);
+      boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Construct a new handle implementation.
   BOOST_ASIO_DECL void construct(implementation_type& impl);
@@ -135,11 +136,11 @@ class win_object_handle_service
     // Allocate and construct an operation to wrap the handler.
     typedef wait_handler<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "object_handle", &impl, "async_wait"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_.context(), *p.p, "object_handle",
+          &impl, reinterpret_cast<uintmax_t>(impl.wait_handle_), "async_wait"));
 
     start_wait_op(impl, p.p);
     p.v = p.p = 0;
@@ -157,8 +158,8 @@ class win_object_handle_service
   static BOOST_ASIO_DECL VOID CALLBACK wait_callback(
       PVOID param, BOOLEAN timeout);
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_;
+  // The io_context implementation used to post completions.
+  io_context_impl& io_context_;
 
   // Mutex to protect access to internal state.
   mutex mutex_;
diff --git a/include/boost/asio/detail/win_thread.hpp b/include/boost/asio/detail/win_thread.hpp
index a138d92ee8..f063330e1d 100644
--- a/include/boost/asio/detail/win_thread.hpp
+++ b/include/boost/asio/detail/win_thread.hpp
@@ -21,6 +21,7 @@
   && !defined(BOOST_ASIO_WINDOWS_APP) \
   && !defined(UNDER_CE)
 
+#include <cstddef>
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/socket_types.hpp>
 
@@ -79,6 +80,9 @@ class win_thread
   // Wait for the thread to exit.
   BOOST_ASIO_DECL void join();
 
+  // Get number of CPUs.
+  BOOST_ASIO_DECL static std::size_t hardware_concurrency();
+
 private:
   friend BOOST_ASIO_DECL unsigned int __stdcall win_thread_function(void* arg);
 
diff --git a/include/boost/asio/detail/winapi_thread.hpp b/include/boost/asio/detail/winapp_thread.hpp
similarity index 66%
rename from include/boost/asio/detail/winapi_thread.hpp
rename to include/boost/asio/detail/winapp_thread.hpp
index 79aba9b519..4b57d228f6 100644
--- a/include/boost/asio/detail/winapi_thread.hpp
+++ b/include/boost/asio/detail/winapp_thread.hpp
@@ -1,5 +1,5 @@
 //
-// detail/winapi_thread.hpp
+// detail/winapp_thread.hpp
 // ~~~~~~~~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
@@ -8,8 +8,8 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_DETAIL_WINAPI_THREAD_HPP
-#define BOOST_ASIO_DETAIL_WINAPI_THREAD_HPP
+#ifndef BOOST_ASIO_DETAIL_WINAPP_THREAD_HPP
+#define BOOST_ASIO_DETAIL_WINAPP_THREAD_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
@@ -17,8 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_WINDOWS)
-#if defined(BOOST_ASIO_WINDOWS_APP) || defined(UNDER_CE)
+#if defined(BOOST_ASIO_WINDOWS) && defined(BOOST_ASIO_WINDOWS_APP)
 
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/scoped_ptr.hpp>
@@ -32,19 +31,19 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-DWORD WINAPI winapi_thread_function(LPVOID arg);
+DWORD WINAPI winapp_thread_function(LPVOID arg);
 
-class winapi_thread
+class winapp_thread
   : private noncopyable
 {
 public:
   // Constructor.
   template <typename Function>
-  winapi_thread(Function f, unsigned int = 0)
+  winapp_thread(Function f, unsigned int = 0)
   {
     scoped_ptr<func_base> arg(new func<Function>(f));
     DWORD thread_id = 0;
-    thread_ = ::CreateThread(0, 0, winapi_thread_function,
+    thread_ = ::CreateThread(0, 0, winapp_thread_function,
         arg.get(), 0, &thread_id);
     if (!thread_)
     {
@@ -57,7 +56,7 @@ class winapi_thread
   }
 
   // Destructor.
-  ~winapi_thread()
+  ~winapp_thread()
   {
     ::CloseHandle(thread_);
   }
@@ -65,15 +64,19 @@ class winapi_thread
   // Wait for the thread to exit.
   void join()
   {
-#if defined(BOOST_ASIO_WINDOWS_APP)
     ::WaitForSingleObjectEx(thread_, INFINITE, false);
-#else // defined(BOOST_ASIO_WINDOWS_APP)
-    ::WaitForSingleObject(thread_, INFINITE);
-#endif // defined(BOOST_ASIO_WINDOWS_APP)
+  }
+
+  // Get number of CPUs.
+  static std::size_t hardware_concurrency()
+  {
+    SYSTEM_INFO system_info;
+    ::GetNativeSystemInfo(&system_info);
+    return system_info.dwNumberOfProcessors;
   }
 
 private:
-  friend DWORD WINAPI winapi_thread_function(LPVOID arg);
+  friend DWORD WINAPI winapp_thread_function(LPVOID arg);
 
   class func_base
   {
@@ -104,10 +107,10 @@ class winapi_thread
   ::HANDLE thread_;
 };
 
-inline DWORD WINAPI winapi_thread_function(LPVOID arg)
+inline DWORD WINAPI winapp_thread_function(LPVOID arg)
 {
-  scoped_ptr<winapi_thread::func_base> func(
-      static_cast<winapi_thread::func_base*>(arg));
+  scoped_ptr<winapp_thread::func_base> func(
+      static_cast<winapp_thread::func_base*>(arg));
   func->run();
   return 0;
 }
@@ -118,7 +121,6 @@ inline DWORD WINAPI winapi_thread_function(LPVOID arg)
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#endif // defined(BOOST_ASIO_WINDOWS_APP) || defined(UNDER_CE)
-#endif // defined(BOOST_ASIO_WINDOWS)
+#endif // defined(BOOST_ASIO_WINDOWS) && defined(BOOST_ASIO_WINDOWS_APP)
 
-#endif // BOOST_ASIO_DETAIL_WINAPI_THREAD_HPP
+#endif // BOOST_ASIO_DETAIL_WINAPP_THREAD_HPP
diff --git a/include/boost/asio/detail/wince_thread.hpp b/include/boost/asio/detail/wince_thread.hpp
new file mode 100644
index 0000000000..cee8b40153
--- /dev/null
+++ b/include/boost/asio/detail/wince_thread.hpp
@@ -0,0 +1,126 @@
+//
+// detail/wince_thread.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_WINCE_THREAD_HPP
+#define BOOST_ASIO_DETAIL_WINCE_THREAD_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_WINDOWS) && defined(UNDER_CE)
+
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/socket_types.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/error.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+DWORD WINAPI wince_thread_function(LPVOID arg);
+
+class wince_thread
+  : private noncopyable
+{
+public:
+  // Constructor.
+  template <typename Function>
+  wince_thread(Function f, unsigned int = 0)
+  {
+    std::auto_ptr<func_base> arg(new func<Function>(f));
+    DWORD thread_id = 0;
+    thread_ = ::CreateThread(0, 0, wince_thread_function,
+        arg.get(), 0, &thread_id);
+    if (!thread_)
+    {
+      DWORD last_error = ::GetLastError();
+      boost::system::error_code ec(last_error,
+          boost::asio::error::get_system_category());
+      boost::asio::detail::throw_error(ec, "thread");
+    }
+    arg.release();
+  }
+
+  // Destructor.
+  ~wince_thread()
+  {
+    ::CloseHandle(thread_);
+  }
+
+  // Wait for the thread to exit.
+  void join()
+  {
+    ::WaitForSingleObject(thread_, INFINITE);
+  }
+
+  // Get number of CPUs.
+  static std::size_t hardware_concurrency()
+  {
+    SYSTEM_INFO system_info;
+    ::GetSystemInfo(&system_info);
+    return system_info.dwNumberOfProcessors;
+  }
+
+private:
+  friend DWORD WINAPI wince_thread_function(LPVOID arg);
+
+  class func_base
+  {
+  public:
+    virtual ~func_base() {}
+    virtual void run() = 0;
+  };
+
+  template <typename Function>
+  class func
+    : public func_base
+  {
+  public:
+    func(Function f)
+      : f_(f)
+    {
+    }
+
+    virtual void run()
+    {
+      f_();
+    }
+
+  private:
+    Function f_;
+  };
+
+  ::HANDLE thread_;
+};
+
+inline DWORD WINAPI wince_thread_function(LPVOID arg)
+{
+  std::auto_ptr<wince_thread::func_base> func(
+      static_cast<wince_thread::func_base*>(arg));
+  func->run();
+  return 0;
+}
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // defined(BOOST_ASIO_WINDOWS) && defined(UNDER_CE)
+
+#endif // BOOST_ASIO_DETAIL_WINCE_THREAD_HPP
diff --git a/include/boost/asio/detail/winrt_async_manager.hpp b/include/boost/asio/detail/winrt_async_manager.hpp
index d6d823d689..7af5357633 100644
--- a/include/boost/asio/detail/winrt_async_manager.hpp
+++ b/include/boost/asio/detail/winrt_async_manager.hpp
@@ -23,7 +23,7 @@
 #include <boost/asio/detail/atomic_count.hpp>
 #include <boost/asio/detail/winrt_async_op.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -36,9 +36,9 @@ class winrt_async_manager
 {
 public:
   // Constructor.
-  winrt_async_manager(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<winrt_async_manager>(io_service),
-      io_service_(use_service<io_service_impl>(io_service)),
+  winrt_async_manager(boost::asio::io_context& io_context)
+    : boost::asio::detail::service_base<winrt_async_manager>(io_context),
+      io_context_(use_service<io_context_impl>(io_context)),
       outstanding_ops_(1)
   {
   }
@@ -49,7 +49,7 @@ class winrt_async_manager
   }
 
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
     if (--outstanding_ops_ > 0)
     {
@@ -186,12 +186,12 @@ class winrt_async_manager
               boost::system::system_category());
           break;
         }
-        io_service_.post_deferred_completion(handler);
+        io_context_.post_deferred_completion(handler);
         if (--outstanding_ops_ == 0)
           promise_.set_value();
       });
 
-    io_service_.work_started();
+    io_context_.work_started();
     ++outstanding_ops_;
     action->Completed = on_completed;
   }
@@ -223,12 +223,12 @@ class winrt_async_manager
               boost::system::system_category());
           break;
         }
-        io_service_.post_deferred_completion(handler);
+        io_context_.post_deferred_completion(handler);
         if (--outstanding_ops_ == 0)
           promise_.set_value();
       });
 
-    io_service_.work_started();
+    io_context_.work_started();
     ++outstanding_ops_;
     operation->Completed = on_completed;
   }
@@ -264,19 +264,19 @@ class winrt_async_manager
                 boost::system::system_category());
             break;
           }
-          io_service_.post_deferred_completion(handler);
+          io_context_.post_deferred_completion(handler);
           if (--outstanding_ops_ == 0)
             promise_.set_value();
         });
 
-    io_service_.work_started();
+    io_context_.work_started();
     ++outstanding_ops_;
     operation->Completed = on_completed;
   }
 
 private:
-  // The io_service implementation used to post completed handlers.
-  io_service_impl& io_service_;
+  // The io_context implementation used to post completed handlers.
+  io_context_impl& io_context_;
 
   // Count of outstanding operations.
   atomic_count outstanding_ops_;
diff --git a/include/boost/asio/detail/winrt_resolve_op.hpp b/include/boost/asio/detail/winrt_resolve_op.hpp
index 12d56933b1..7a98345a09 100644
--- a/include/boost/asio/detail/winrt_resolve_op.hpp
+++ b/include/boost/asio/detail/winrt_resolve_op.hpp
@@ -19,13 +19,13 @@
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/winrt_async_op.hpp>
-#include <boost/asio/ip/basic_resolver_iterator.hpp>
+#include <boost/asio/ip/basic_resolver_results.hpp>
 #include <boost/asio/error.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -45,7 +45,7 @@ class winrt_resolve_op :
 
   typedef typename Protocol::endpoint endpoint_type;
   typedef boost::asio::ip::basic_resolver_query<Protocol> query_type;
-  typedef boost::asio::ip::basic_resolver_iterator<Protocol> iterator_type;
+  typedef boost::asio::ip::basic_resolver_results<Protocol> results_type;
 
   winrt_resolve_op(const query_type& query, Handler& handler)
     : winrt_async_op<
@@ -55,24 +55,25 @@ class winrt_resolve_op :
       query_(query),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code&, std::size_t)
   {
     // Take ownership of the operation object.
     winrt_resolve_op* o(static_cast<winrt_resolve_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
-    iterator_type iterator = iterator_type();
+    results_type results = results_type();
     if (!o->ec_)
     {
       try
       {
-        iterator = iterator_type::create(
-            o->result_, o->query_.hints(),
+        results = results_type::create(o->result_, o->query_.hints(),
             o->query_.host_name(), o->query_.service_name());
       }
       catch (Platform::Exception^ e)
@@ -88,8 +89,8 @@ class winrt_resolve_op :
     // with the handler. Consequently, a local copy of the handler is required
     // to ensure that any owning sub-object remains valid until after we have
     // deallocated the memory here.
-    detail::binder2<Handler, boost::system::error_code, iterator_type>
-      handler(o->handler_, o->ec_, iterator);
+    detail::binder2<Handler, boost::system::error_code, results_type>
+      handler(o->handler_, o->ec_, results);
     p.h = boost::asio::detail::addressof(handler.handler_);
     p.reset();
 
@@ -97,8 +98,8 @@ class winrt_resolve_op :
     if (owner)
     {
       fenced_block b(fenced_block::half);
-      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/winrt_resolver_service.hpp b/include/boost/asio/detail/winrt_resolver_service.hpp
index dfd1dddeb2..30e50e4f00 100644
--- a/include/boost/asio/detail/winrt_resolver_service.hpp
+++ b/include/boost/asio/detail/winrt_resolver_service.hpp
@@ -19,10 +19,10 @@
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-#include <boost/asio/ip/basic_resolver_iterator.hpp>
 #include <boost/asio/ip/basic_resolver_query.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/ip/basic_resolver_results.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/detail/winrt_async_manager.hpp>
 #include <boost/asio/detail/winrt_resolve_op.hpp>
@@ -35,7 +35,8 @@ namespace asio {
 namespace detail {
 
 template <typename Protocol>
-class winrt_resolver_service
+class winrt_resolver_service :
+  public service_base<winrt_resolver_service<Protocol> >
 {
 public:
   // The implementation type of the resolver. A cancellation token is used to
@@ -49,13 +50,14 @@ class winrt_resolver_service
   // The query type.
   typedef boost::asio::ip::basic_resolver_query<Protocol> query_type;
 
-  // The iterator type.
-  typedef boost::asio::ip::basic_resolver_iterator<Protocol> iterator_type;
+  // The results type.
+  typedef boost::asio::ip::basic_resolver_results<Protocol> results_type;
 
   // Constructor.
-  winrt_resolver_service(boost::asio::io_service& io_service)
-    : io_service_(use_service<io_service_impl>(io_service)),
-      async_manager_(use_service<winrt_async_manager>(io_service))
+  winrt_resolver_service(boost::asio::io_context& io_context)
+    : service_base<winrt_resolver_service<Protocol> >(io_context),
+      io_context_(use_service<io_context_impl>(io_context)),
+      async_manager_(use_service<winrt_async_manager>(io_context))
   {
   }
 
@@ -65,12 +67,12 @@ class winrt_resolver_service
   }
 
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
   }
 
   // Perform any fork-related housekeeping.
-  void fork_service(boost::asio::io_service::fork_event)
+  void notify_fork(boost::asio::io_context::fork_event)
   {
   }
 
@@ -79,6 +81,18 @@ class winrt_resolver_service
   {
   }
 
+  // Move-construct a new resolver implementation.
+  void move_construct(implementation_type&,
+      implementation_type&)
+  {
+  }
+
+  // Move-assign from another resolver implementation.
+  void move_assign(implementation_type&,
+      winrt_resolver_service&, implementation_type&)
+  {
+  }
+
   // Destroy a resolver implementation.
   void destroy(implementation_type&)
   {
@@ -90,7 +104,7 @@ class winrt_resolver_service
   }
 
   // Resolve a query to a list of entries.
-  iterator_type resolve(implementation_type&,
+  results_type resolve(implementation_type&,
       const query_type& query, boost::system::error_code& ec)
   {
     try
@@ -102,9 +116,9 @@ class winrt_resolver_service
             winrt_utils::string(query.service_name())), ec);
 
       if (ec)
-        return iterator_type();
+        return results_type();
 
-      return iterator_type::create(
+      return results_type::create(
           endpoint_pairs, query.hints(),
           query.host_name(), query.service_name());
     }
@@ -112,13 +126,13 @@ class winrt_resolver_service
     {
       ec = boost::system::error_code(e->HResult,
           boost::system::system_category());
-      return iterator_type();
+      return results_type();
     }
   }
 
   // Asynchronously resolve a query to a list of entries.
   template <typename Handler>
-  void async_resolve(implementation_type&,
+  void async_resolve(implementation_type& impl,
       const query_type& query, Handler& handler)
   {
     bool is_continuation =
@@ -127,11 +141,12 @@ class winrt_resolver_service
     // Allocate and construct an operation to wrap the handler.
     typedef winrt_resolve_op<Protocol, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(query, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "resolver", &impl, "async_resolve"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_.context(),
+          *p.p, "resolver", &impl, 0, "async_resolve"));
+    (void)impl;
 
     try
     {
@@ -145,17 +160,17 @@ class winrt_resolver_service
     {
       p.p->ec_ = boost::system::error_code(
           e->HResult, boost::system::system_category());
-      io_service_.post_immediate_completion(p.p, is_continuation);
+      io_context_.post_immediate_completion(p.p, is_continuation);
       p.v = p.p = 0;
     }
   }
 
   // Resolve an endpoint to a list of entries.
-  iterator_type resolve(implementation_type&,
+  results_type resolve(implementation_type&,
       const endpoint_type&, boost::system::error_code& ec)
   {
     ec = boost::asio::error::operation_not_supported;
-    return iterator_type();
+    return results_type();
   }
 
   // Asynchronously resolve an endpoint to a list of entries.
@@ -164,13 +179,13 @@ class winrt_resolver_service
       const endpoint_type&, Handler& handler)
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
-    const iterator_type iterator;
-    io_service_.get_io_service().post(
-        detail::bind_handler(handler, ec, iterator));
+    const results_type results;
+    io_context_.get_io_context().post(
+        detail::bind_handler(handler, ec, results));
   }
 
 private:
-  io_service_impl& io_service_;
+  io_context_impl& io_context_;
   winrt_async_manager& async_manager_;
 };
 
diff --git a/include/boost/asio/detail/winrt_socket_connect_op.hpp b/include/boost/asio/detail/winrt_socket_connect_op.hpp
index 548f7d631a..6fc1ab0c7f 100644
--- a/include/boost/asio/detail/winrt_socket_connect_op.hpp
+++ b/include/boost/asio/detail/winrt_socket_connect_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/winrt_async_op.hpp>
 #include <boost/asio/error.hpp>
 
@@ -45,16 +45,18 @@ class winrt_socket_connect_op :
     : winrt_async_op<void>(&winrt_socket_connect_op::do_complete),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code&, std::size_t)
   {
     // Take ownership of the operation object.
     winrt_socket_connect_op* o(static_cast<winrt_socket_connect_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
     // Make a copy of the handler so that the memory can be deallocated before
     // the upcall is made. Even if we're not about to make an upcall, a
@@ -71,8 +73,8 @@ class winrt_socket_connect_op :
     if (owner)
     {
       fenced_block b(fenced_block::half);
-      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_));
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/winrt_socket_recv_op.hpp b/include/boost/asio/detail/winrt_socket_recv_op.hpp
index 2cbbb3c8d8..137ed5a118 100644
--- a/include/boost/asio/detail/winrt_socket_recv_op.hpp
+++ b/include/boost/asio/detail/winrt_socket_recv_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/winrt_async_op.hpp>
 #include <boost/asio/error.hpp>
 
@@ -47,16 +47,18 @@ class winrt_socket_recv_op :
       buffers_(buffers),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code&, std::size_t)
   {
     // Take ownership of the operation object.
     winrt_socket_recv_op* o(static_cast<winrt_socket_recv_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     // Check whether buffers are still valid.
@@ -91,7 +93,7 @@ class winrt_socket_recv_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/winrt_socket_send_op.hpp b/include/boost/asio/detail/winrt_socket_send_op.hpp
index 591d9536c3..301c4127a6 100644
--- a/include/boost/asio/detail/winrt_socket_send_op.hpp
+++ b/include/boost/asio/detail/winrt_socket_send_op.hpp
@@ -19,12 +19,12 @@
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
 #include <boost/asio/detail/fenced_block.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/winrt_async_op.hpp>
 #include <boost/asio/error.hpp>
 
@@ -46,16 +46,18 @@ class winrt_socket_send_op :
       buffers_(buffers),
       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
+    handler_work<Handler>::start(handler_);
   }
 
-  static void do_complete(io_service_impl* owner, operation* base,
+  static void do_complete(void* owner, operation* base,
       const boost::system::error_code&, std::size_t)
   {
     // Take ownership of the operation object.
     winrt_socket_send_op* o(static_cast<winrt_socket_send_op*>(base));
     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
+    handler_work<Handler> w(o->handler_);
 
-    BOOST_ASIO_HANDLER_COMPLETION((o));
+    BOOST_ASIO_HANDLER_COMPLETION((*o));
 
 #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
     // Check whether buffers are still valid.
@@ -82,7 +84,7 @@ class winrt_socket_send_op :
     {
       fenced_block b(fenced_block::half);
       BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
-      boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
+      w.complete(handler, handler.handler_);
       BOOST_ASIO_HANDLER_INVOCATION_END;
     }
   }
diff --git a/include/boost/asio/detail/winrt_ssocket_service.hpp b/include/boost/asio/detail/winrt_ssocket_service.hpp
index b9b1910e78..a1e15db545 100644
--- a/include/boost/asio/detail/winrt_ssocket_service.hpp
+++ b/include/boost/asio/detail/winrt_ssocket_service.hpp
@@ -20,8 +20,8 @@
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/winrt_socket_connect_op.hpp>
 #include <boost/asio/detail/winrt_ssocket_service_base.hpp>
 #include <boost/asio/detail/winrt_utils.hpp>
@@ -34,6 +34,7 @@ namespace detail {
 
 template <typename Protocol>
 class winrt_ssocket_service :
+  public service_base<winrt_ssocket_service<Protocol> >,
   public winrt_ssocket_service_base
 {
 public:
@@ -61,11 +62,18 @@ class winrt_ssocket_service :
   };
 
   // Constructor.
-  winrt_ssocket_service(boost::asio::io_service& io_service)
-    : winrt_ssocket_service_base(io_service)
+  winrt_ssocket_service(boost::asio::io_context& io_context)
+    : service_base<winrt_ssocket_service<Protocol> >(io_context),
+      winrt_ssocket_service_base(io_context)
   {
   }
 
+  // Destroy all user-defined handler objects owned by the service.
+  void shutdown()
+  {
+    this->base_shutdown();
+  }
+
   // Move-construct a new socket implementation.
   void move_construct(implementation_type& impl,
       implementation_type& other_impl)
@@ -213,11 +221,11 @@ class winrt_ssocket_service :
     // Allocate and construct an operation to wrap the handler.
     typedef winrt_socket_connect_op<Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_connect"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_.context(),
+          *p.p, "socket", &impl, 0, "async_connect"));
 
     start_connect_op(impl, peer_endpoint.data(), p.p, is_continuation);
     p.v = p.p = 0;
diff --git a/include/boost/asio/detail/winrt_ssocket_service_base.hpp b/include/boost/asio/detail/winrt_ssocket_service_base.hpp
index 88e5674576..c18722466f 100644
--- a/include/boost/asio/detail/winrt_ssocket_service_base.hpp
+++ b/include/boost/asio/detail/winrt_ssocket_service_base.hpp
@@ -21,10 +21,10 @@
 
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/socket_base.hpp>
-#include <boost/asio/detail/addressof.hpp>
 #include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/socket_types.hpp>
 #include <boost/asio/detail/winrt_async_manager.hpp>
 #include <boost/asio/detail/winrt_socket_recv_op.hpp>
@@ -63,10 +63,10 @@ class winrt_ssocket_service_base
 
   // Constructor.
   BOOST_ASIO_DECL winrt_ssocket_service_base(
-      boost::asio::io_service& io_service);
+      boost::asio::io_context& io_context);
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void base_shutdown();
 
   // Construct a new socket implementation.
   BOOST_ASIO_DECL void construct(base_implementation_type&);
@@ -93,6 +93,10 @@ class winrt_ssocket_service_base
   BOOST_ASIO_DECL boost::system::error_code close(
       base_implementation_type& impl, boost::system::error_code& ec);
 
+  // Release ownership of the socket.
+  BOOST_ASIO_DECL native_handle_type release(
+      base_implementation_type& impl, boost::system::error_code& ec);
+
   // Get the native socket representation.
   native_handle_type native_handle(base_implementation_type& impl)
   {
@@ -200,11 +204,11 @@ class winrt_ssocket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef winrt_socket_send_op<ConstBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_send"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_.context(),
+          *p.p, "socket", &impl, 0, "async_send"));
 
     start_send_op(impl,
         buffer_sequence_adapter<boost::asio::const_buffer,
@@ -220,7 +224,7 @@ class winrt_ssocket_service_base
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.get_io_service().post(
+    io_context_.get_io_context().post(
         detail::bind_handler(handler, ec, bytes_transferred));
   }
 
@@ -256,11 +260,11 @@ class winrt_ssocket_service_base
     // Allocate and construct an operation to wrap the handler.
     typedef winrt_socket_recv_op<MutableBufferSequence, Handler> op;
     typename op::ptr p = { boost::asio::detail::addressof(handler),
-      boost_asio_handler_alloc_helpers::allocate(
-        sizeof(op), handler), 0 };
+      op::ptr::allocate(handler), 0 };
     p.p = new (p.v) op(buffers, handler);
 
-    BOOST_ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_receive"));
+    BOOST_ASIO_HANDLER_CREATION((io_context_.context(),
+          *p.p, "socket", &impl, 0, "async_receive"));
 
     start_receive_op(impl,
         buffer_sequence_adapter<boost::asio::mutable_buffer,
@@ -276,7 +280,7 @@ class winrt_ssocket_service_base
   {
     boost::system::error_code ec = boost::asio::error::operation_not_supported;
     const std::size_t bytes_transferred = 0;
-    io_service_.get_io_service().post(
+    io_context_.get_io_context().post(
         detail::bind_handler(handler, ec, bytes_transferred));
   }
 
@@ -329,8 +333,8 @@ class winrt_ssocket_service_base
       winrt_async_op<Windows::Storage::Streams::IBuffer^>* op,
       bool is_continuation);
 
-  // The io_service implementation used for delivering completions.
-  io_service_impl& io_service_;
+  // The io_context implementation used for delivering completions.
+  io_context_impl& io_context_;
 
   // The manager that keeps track of outstanding operations.
   winrt_async_manager& async_manager_;
diff --git a/include/boost/asio/detail/winrt_timer_scheduler.hpp b/include/boost/asio/detail/winrt_timer_scheduler.hpp
index 8b119b2724..9dd9d050ce 100644
--- a/include/boost/asio/detail/winrt_timer_scheduler.hpp
+++ b/include/boost/asio/detail/winrt_timer_scheduler.hpp
@@ -28,7 +28,7 @@
 #include <boost/asio/detail/timer_queue_base.hpp>
 #include <boost/asio/detail/timer_queue_set.hpp>
 #include <boost/asio/detail/wait_op.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #if defined(BOOST_ASIO_HAS_IOCP)
 # include <boost/asio/detail/thread.hpp>
@@ -45,17 +45,17 @@ class winrt_timer_scheduler
 {
 public:
   // Constructor.
-  BOOST_ASIO_DECL winrt_timer_scheduler(boost::asio::io_service& io_service);
+  BOOST_ASIO_DECL winrt_timer_scheduler(boost::asio::io_context& io_context);
 
   // Destructor.
   BOOST_ASIO_DECL ~winrt_timer_scheduler();
 
   // Destroy all user-defined handler objects owned by the service.
-  BOOST_ASIO_DECL void shutdown_service();
+  BOOST_ASIO_DECL void shutdown();
 
   // Recreate internal descriptors following a fork.
-  BOOST_ASIO_DECL void fork_service(
-      boost::asio::io_service::fork_event fork_ev);
+  BOOST_ASIO_DECL void notify_fork(
+      boost::asio::io_context::fork_event fork_ev);
 
   // Initialise the task. No effect as this class uses its own thread.
   BOOST_ASIO_DECL void init_task();
@@ -82,6 +82,12 @@ class winrt_timer_scheduler
       typename timer_queue<Time_Traits>::per_timer_data& timer,
       std::size_t max_cancelled = (std::numeric_limits<std::size_t>::max)());
 
+  // Move the timer operations associated with the given timer.
+  template <typename Time_Traits>
+  void move_timer(timer_queue<Time_Traits>& queue,
+      typename timer_queue<Time_Traits>::per_timer_data& to,
+      typename timer_queue<Time_Traits>::per_timer_data& from);
+
 private:
   // Run the select loop in the thread.
   BOOST_ASIO_DECL void run_thread();
@@ -95,8 +101,8 @@ class winrt_timer_scheduler
   // Helper function to remove a timer queue.
   BOOST_ASIO_DECL void do_remove_timer_queue(timer_queue_base& queue);
 
-  // The io_service implementation used to post completions.
-  io_service_impl& io_service_;
+  // The io_context implementation used to post completions.
+  io_context_impl& io_context_;
 
   // Mutex used to protect internal variables.
   boost::asio::detail::mutex mutex_;
diff --git a/include/boost/asio/detail/winrt_utils.hpp b/include/boost/asio/detail/winrt_utils.hpp
index 351aa62f23..0aebacbbb9 100644
--- a/include/boost/asio/detail/winrt_utils.hpp
+++ b/include/boost/asio/detail/winrt_utils.hpp
@@ -23,13 +23,12 @@
 #include <cstdlib>
 #include <future>
 #include <locale>
-#include <memory>
 #include <robuffer.h>
 #include <windows.storage.streams.h>
 #include <wrl/implements.h>
 #include <boost/asio/buffer.hpp>
 #include <boost/system/error_code.hpp>
-#include <boost/asio/detail/addressof.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -84,7 +83,8 @@ inline Windows::Storage::Streams::IBuffer^ buffer_dup(
     const ConstBufferSequence& buffers)
 {
   using Microsoft::WRL::ComPtr;
-  std::size_t size = boost::asio::buffer_size(buffers);
+  using boost::asio::buffer_size;
+  std::size_t size = buffer_size(buffers);
   auto b = ref new Windows::Storage::Streams::Buffer(size);
   ComPtr<IInspectable> insp = reinterpret_cast<IInspectable*>(b);
   ComPtr<Windows::Storage::Streams::IBufferByteAccess> bacc;
diff --git a/include/boost/asio/detail/work_dispatcher.hpp b/include/boost/asio/detail/work_dispatcher.hpp
new file mode 100644
index 0000000000..7ccacd5546
--- /dev/null
+++ b/include/boost/asio/detail/work_dispatcher.hpp
@@ -0,0 +1,74 @@
+//
+// detail/work_dispatcher.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DETAIL_WORK_DISPATCHER_HPP
+#define BOOST_ASIO_DETAIL_WORK_DISPATCHER_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/executor_work_guard.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename Handler>
+class work_dispatcher
+{
+public:
+  work_dispatcher(Handler& handler)
+    : work_((get_associated_executor)(handler)),
+      handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  work_dispatcher(const work_dispatcher& other)
+    : work_(other.work_),
+      handler_(other.handler_)
+  {
+  }
+
+  work_dispatcher(work_dispatcher&& other)
+    : work_(BOOST_ASIO_MOVE_CAST(executor_work_guard<
+        typename associated_executor<Handler>::type>)(other.work_)),
+      handler_(BOOST_ASIO_MOVE_CAST(Handler)(other.handler_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  void operator()()
+  {
+    typename associated_allocator<Handler>::type alloc(
+        (get_associated_allocator)(handler_));
+    work_.get_executor().dispatch(
+        BOOST_ASIO_MOVE_CAST(Handler)(handler_), alloc);
+    work_.reset();
+  }
+
+private:
+  executor_work_guard<typename associated_executor<Handler>::type> work_;
+  Handler handler_;
+};
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_DETAIL_WORK_DISPATCHER_HPP
diff --git a/include/boost/asio/dispatch.hpp b/include/boost/asio/dispatch.hpp
new file mode 100644
index 0000000000..c2ea0c8999
--- /dev/null
+++ b/include/boost/asio/dispatch.hpp
@@ -0,0 +1,110 @@
+//
+// dispatch.hpp
+// ~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_DISPATCH_HPP
+#define BOOST_ASIO_DISPATCH_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/execution_context.hpp>
+#include <boost/asio/is_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// Submits a completion token or function object for execution.
+/**
+ * This function submits an object for execution using the object's associated
+ * executor. The function object is queued for execution, and is never called
+ * from the current thread prior to returning from <tt>dispatch()</tt>.
+ *
+ * This function has the following effects:
+ *
+ * @li Constructs a function object handler of type @c Handler, initialized
+ * with <tt>handler(forward<CompletionToken>(token))</tt>.
+ *
+ * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
+ * initializing the object as <tt>result(handler)</tt>.
+ *
+ * @li Obtains the handler's associated executor object @c ex by performing
+ * <tt>get_associated_executor(handler)</tt>.
+ *
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * <tt>get_associated_allocator(handler)</tt>.
+ *
+ * @li Performs <tt>ex.dispatch(std::move(handler), alloc)</tt>.
+ *
+ * @li Returns <tt>result.get()</tt>.
+ */
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) dispatch(
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token);
+
+/// Submits a completion token or function object for execution.
+/**
+ * This function submits an object for execution using the specified executor.
+ * The function object is queued for execution, and is never called from the
+ * current thread prior to returning from <tt>dispatch()</tt>.
+ *
+ * This function has the following effects:
+ *
+ * @li Constructs a function object handler of type @c Handler, initialized
+ * with <tt>handler(forward<CompletionToken>(token))</tt>.
+ *
+ * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
+ * initializing the object as <tt>result(handler)</tt>.
+ *
+ * @li Obtains the handler's associated executor object @c ex1 by performing
+ * <tt>get_associated_executor(handler)</tt>.
+ *
+ * @li Creates a work object @c w by performing <tt>make_work(ex1)</tt>.
+ *
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * <tt>get_associated_allocator(handler)</tt>.
+ *
+ * @li Constructs a function object @c f with a function call operator that
+ * performs <tt>ex1.dispatch(std::move(handler), alloc)</tt> followed by
+ * <tt>w.reset()</tt>.
+ *
+ * @li Performs <tt>Executor(ex).dispatch(std::move(f), alloc)</tt>.
+ *
+ * @li Returns <tt>result.get()</tt>.
+ */
+template <typename Executor, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) dispatch(
+    const Executor& ex, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_executor<Executor>::value>::type* = 0);
+
+/// Submits a completion token or function object for execution.
+/**
+ * @returns <tt>dispatch(ctx.get_executor(),
+ * forward<CompletionToken>(token))</tt>.
+ */
+template <typename ExecutionContext, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) dispatch(
+    ExecutionContext& ctx, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type* = 0);
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/dispatch.hpp>
+
+#endif // BOOST_ASIO_DISPATCH_HPP
diff --git a/include/boost/asio/error.hpp b/include/boost/asio/error.hpp
index dd338fb156..8f1f74cb91 100644
--- a/include/boost/asio/error.hpp
+++ b/include/boost/asio/error.hpp
@@ -327,6 +327,22 @@ inline boost::system::error_code make_error_code(misc_errors e)
 }
 
 } // namespace error
+namespace stream_errc {
+  // Simulates the proposed stream_errc scoped enum.
+  using error::eof;
+  using error::not_found;
+} // namespace stream_errc
+namespace socket_errc {
+  // Simulates the proposed socket_errc scoped enum.
+  using error::already_open;
+  using error::not_found;
+} // namespace socket_errc
+namespace resolver_errc {
+  // Simulates the proposed resolver_errc scoped enum.
+  using error::host_not_found;
+  const error::netdb_errors try_again = error::host_not_found_try_again;
+  using error::service_not_found;
+} // namespace resolver_errc
 } // namespace asio
 } // namespace boost
 
diff --git a/include/boost/asio/execution_context.hpp b/include/boost/asio/execution_context.hpp
new file mode 100644
index 0000000000..9feb30c45d
--- /dev/null
+++ b/include/boost/asio/execution_context.hpp
@@ -0,0 +1,413 @@
+//
+// execution_context.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_EXECUTION_CONTEXT_HPP
+#define BOOST_ASIO_EXECUTION_CONTEXT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <cstddef>
+#include <stdexcept>
+#include <typeinfo>
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/variadic_templates.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+class execution_context;
+class io_context;
+
+#if !defined(GENERATING_DOCUMENTATION)
+template <typename Service> Service& use_service(execution_context&);
+template <typename Service> Service& use_service(io_context&);
+template <typename Service> void add_service(execution_context&, Service*);
+template <typename Service> bool has_service(execution_context&);
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+namespace detail { class service_registry; }
+
+/// A context for function object execution.
+/**
+ * An execution context represents a place where function objects will be
+ * executed. An @c io_context is an example of an execution context.
+ *
+ * @par The execution_context class and services
+ *
+ * Class execution_context implements an extensible, type-safe, polymorphic set
+ * of services, indexed by service type.
+ *
+ * Services exist to manage the resources that are shared across an execution
+ * context. For example, timers may be implemented in terms of a single timer
+ * queue, and this queue would be stored in a service.
+ *
+ * Access to the services of an execution_context is via three function
+ * templates, use_service(), add_service() and has_service().
+ *
+ * In a call to @c use_service<Service>(), the type argument chooses a service,
+ * making available all members of the named type. If @c Service is not present
+ * in an execution_context, an object of type @c Service is created and added
+ * to the execution_context. A C++ program can check if an execution_context
+ * implements a particular service with the function template @c
+ * has_service<Service>().
+ *
+ * Service objects may be explicitly added to an execution_context using the
+ * function template @c add_service<Service>(). If the @c Service is already
+ * present, the service_already_exists exception is thrown. If the owner of the
+ * service is not the same object as the execution_context parameter, the
+ * invalid_service_owner exception is thrown.
+ *
+ * Once a service reference is obtained from an execution_context object by
+ * calling use_service(), that reference remains usable as long as the owning
+ * execution_context object exists.
+ *
+ * All service implementations have execution_context::service as a public base
+ * class. Custom services may be implemented by deriving from this class and
+ * then added to an execution_context using the facilities described above.
+ *
+ * @par The execution_context as a base class
+ *
+ * Class execution_context may be used only as a base class for concrete
+ * execution context types. The @c io_context is an example of such a derived
+ * type.
+ *
+ * On destruction, a class that is derived from execution_context must perform
+ * <tt>execution_context::shutdown()</tt> followed by
+ * <tt>execution_context::destroy()</tt>.
+ *
+ * This destruction sequence permits programs to simplify their resource
+ * management by using @c shared_ptr<>. Where an object's lifetime is tied to
+ * the lifetime of a connection (or some other sequence of asynchronous
+ * operations), a @c shared_ptr to the object would be bound into the handlers
+ * for all asynchronous operations associated with it. This works as follows:
+ *
+ * @li When a single connection ends, all associated asynchronous operations
+ * complete. The corresponding handler objects are destroyed, and all @c
+ * shared_ptr references to the objects are destroyed.
+ *
+ * @li To shut down the whole program, the io_context function stop() is called
+ * to terminate any run() calls as soon as possible. The io_context destructor
+ * calls @c shutdown() and @c destroy() to destroy all pending handlers,
+ * causing all @c shared_ptr references to all connection objects to be
+ * destroyed.
+ */
+class execution_context
+  : private noncopyable
+{
+public:
+  class id;
+  class service;
+
+protected:
+  /// Constructor.
+  BOOST_ASIO_DECL execution_context();
+
+  /// Destructor.
+  BOOST_ASIO_DECL ~execution_context();
+
+  /// Shuts down all services in the context.
+  /**
+   * This function is implemented as follows:
+   *
+   * @li For each service object @c svc in the execution_context set, in
+   * reverse order of the beginning of service object lifetime, performs @c
+   * svc->shutdown().
+   */
+  BOOST_ASIO_DECL void shutdown();
+
+  /// Destroys all services in the context.
+  /**
+   * This function is implemented as follows:
+   *
+   * @li For each service object @c svc in the execution_context set, in
+   * reverse order * of the beginning of service object lifetime, performs
+   * <tt>delete static_cast<execution_context::service*>(svc)</tt>.
+   */
+  BOOST_ASIO_DECL void destroy();
+
+public:
+  /// Fork-related event notifications.
+  enum fork_event
+  {
+    /// Notify the context that the process is about to fork.
+    fork_prepare,
+
+    /// Notify the context that the process has forked and is the parent.
+    fork_parent,
+
+    /// Notify the context that the process has forked and is the child.
+    fork_child
+  };
+
+  /// Notify the execution_context of a fork-related event.
+  /**
+   * This function is used to inform the execution_context that the process is
+   * about to fork, or has just forked. This allows the execution_context, and
+   * the services it contains, to perform any necessary housekeeping to ensure
+   * correct operation following a fork.
+   *
+   * This function must not be called while any other execution_context
+   * function, or any function associated with the execution_context's derived
+   * class, is being called in another thread. It is, however, safe to call
+   * this function from within a completion handler, provided no other thread
+   * is accessing the execution_context or its derived class.
+   *
+   * @param event A fork-related event.
+   *
+   * @throws boost::system::system_error Thrown on failure. If the notification
+   * fails the execution_context object should no longer be used and should be
+   * destroyed.
+   *
+   * @par Example
+   * The following code illustrates how to incorporate the notify_fork()
+   * function:
+   * @code my_execution_context.notify_fork(execution_context::fork_prepare);
+   * if (fork() == 0)
+   * {
+   *   // This is the child process.
+   *   my_execution_context.notify_fork(execution_context::fork_child);
+   * }
+   * else
+   * {
+   *   // This is the parent process.
+   *   my_execution_context.notify_fork(execution_context::fork_parent);
+   * } @endcode
+   *
+   * @note For each service object @c svc in the execution_context set,
+   * performs <tt>svc->notify_fork();</tt>. When processing the fork_prepare
+   * event, services are visited in reverse order of the beginning of service
+   * object lifetime. Otherwise, services are visited in order of the beginning
+   * of service object lifetime.
+   */
+  BOOST_ASIO_DECL void notify_fork(fork_event event);
+
+  /// Obtain the service object corresponding to the given type.
+  /**
+   * This function is used to locate a service object that corresponds to the
+   * given service type. If there is no existing implementation of the service,
+   * then the execution_context will create a new instance of the service.
+   *
+   * @param e The execution_context object that owns the service.
+   *
+   * @return The service interface implementing the specified service type.
+   * Ownership of the service interface is not transferred to the caller.
+   */
+  template <typename Service>
+  friend Service& use_service(execution_context& e);
+
+  /// Obtain the service object corresponding to the given type.
+  /**
+   * This function is used to locate a service object that corresponds to the
+   * given service type. If there is no existing implementation of the service,
+   * then the io_context will create a new instance of the service.
+   *
+   * @param ioc The io_context object that owns the service.
+   *
+   * @return The service interface implementing the specified service type.
+   * Ownership of the service interface is not transferred to the caller.
+   *
+   * @note This overload is preserved for backwards compatibility with services
+   * that inherit from io_context::service.
+   */
+  template <typename Service>
+  friend Service& use_service(io_context& ioc);
+
+#if defined(GENERATING_DOCUMENTATION)
+
+  /// Creates a service object and adds it to the execution_context.
+  /**
+   * This function is used to add a service to the execution_context.
+   *
+   * @param e The execution_context object that owns the service.
+   *
+   * @param args Zero or more arguments to be passed to the service
+   * constructor.
+   *
+   * @throws boost::asio::service_already_exists Thrown if a service of the
+   * given type is already present in the execution_context.
+   */
+  template <typename Service, typename... Args>
+  friend Service& make_service(execution_context& e, Args&&... args);
+
+#elif defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename Service, typename... Args>
+  friend Service& make_service(execution_context& e,
+      BOOST_ASIO_MOVE_ARG(Args)... args);
+
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename Service>
+  friend Service& make_service(execution_context& e);
+
+#define BOOST_ASIO_PRIVATE_MAKE_SERVICE_DEF(n) \
+  template <typename Service, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  friend Service& make_service(execution_context& e, \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)); \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_MAKE_SERVICE_DEF)
+#undef BOOST_ASIO_PRIVATE_MAKE_SERVICE_DEF
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  /// (Deprecated: Use make_service().) Add a service object to the
+  /// execution_context.
+  /**
+   * This function is used to add a service to the execution_context.
+   *
+   * @param e The execution_context object that owns the service.
+   *
+   * @param svc The service object. On success, ownership of the service object
+   * is transferred to the execution_context. When the execution_context object
+   * is destroyed, it will destroy the service object by performing: @code
+   * delete static_cast<execution_context::service*>(svc) @endcode
+   *
+   * @throws boost::asio::service_already_exists Thrown if a service of the
+   * given type is already present in the execution_context.
+   *
+   * @throws boost::asio::invalid_service_owner Thrown if the service's owning
+   * execution_context is not the execution_context object specified by the
+   * @c e parameter.
+   */
+  template <typename Service>
+  friend void add_service(execution_context& e, Service* svc);
+
+  /// Determine if an execution_context contains a specified service type.
+  /**
+   * This function is used to determine whether the execution_context contains a
+   * service object corresponding to the given service type.
+   *
+   * @param e The execution_context object that owns the service.
+   *
+   * @return A boolean indicating whether the execution_context contains the
+   * service.
+   */
+  template <typename Service>
+  friend bool has_service(execution_context& e);
+
+private:
+  // The service registry.
+  boost::asio::detail::service_registry* service_registry_;
+};
+
+/// Class used to uniquely identify a service.
+class execution_context::id
+  : private noncopyable
+{
+public:
+  /// Constructor.
+  id() {}
+};
+
+/// Base class for all io_context services.
+class execution_context::service
+  : private noncopyable
+{
+public:
+  /// Get the context object that owns the service.
+  execution_context& context();
+
+protected:
+  /// Constructor.
+  /**
+   * @param owner The execution_context object that owns the service.
+   */
+  BOOST_ASIO_DECL service(execution_context& owner);
+
+  /// Destructor.
+  BOOST_ASIO_DECL virtual ~service();
+
+private:
+  /// Destroy all user-defined handler objects owned by the service.
+  virtual void shutdown() = 0;
+
+  /// Handle notification of a fork-related event to perform any necessary
+  /// housekeeping.
+  /**
+   * This function is not a pure virtual so that services only have to
+   * implement it if necessary. The default implementation does nothing.
+   */
+  BOOST_ASIO_DECL virtual void notify_fork(
+      execution_context::fork_event event);
+
+  friend class boost::asio::detail::service_registry;
+  struct key
+  {
+    key() : type_info_(0), id_(0) {}
+    const std::type_info* type_info_;
+    const execution_context::id* id_;
+  } key_;
+
+  execution_context& owner_;
+  service* next_;
+};
+
+/// Exception thrown when trying to add a duplicate service to an
+/// execution_context.
+class service_already_exists
+  : public std::logic_error
+{
+public:
+  BOOST_ASIO_DECL service_already_exists();
+};
+
+/// Exception thrown when trying to add a service object to an
+/// execution_context where the service has a different owner.
+class invalid_service_owner
+  : public std::logic_error
+{
+public:
+  BOOST_ASIO_DECL invalid_service_owner();
+};
+
+namespace detail {
+
+// Special derived service id type to keep classes header-file only.
+template <typename Type>
+class service_id
+  : public execution_context::id
+{
+};
+
+// Special service base class to keep classes header-file only.
+template <typename Type>
+class execution_context_service_base
+  : public execution_context::service
+{
+public:
+  static service_id<Type> id;
+
+  // Constructor.
+  execution_context_service_base(execution_context& e)
+    : execution_context::service(e)
+  {
+  }
+};
+
+template <typename Type>
+service_id<Type> execution_context_service_base<Type>::id;
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/execution_context.hpp>
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/impl/execution_context.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+#endif // BOOST_ASIO_EXECUTION_CONTEXT_HPP
diff --git a/include/boost/asio/executor.hpp b/include/boost/asio/executor.hpp
new file mode 100644
index 0000000000..f519842361
--- /dev/null
+++ b/include/boost/asio/executor.hpp
@@ -0,0 +1,343 @@
+//
+// executor.hpp
+// ~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_EXECUTOR_HPP
+#define BOOST_ASIO_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <typeinfo>
+#include <boost/asio/detail/cstddef.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/throw_exception.hpp>
+#include <boost/asio/execution_context.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// Exception thrown when trying to access an empty polymorphic executor.
+class bad_executor
+  : public std::exception
+{
+public:
+  /// Constructor.
+  BOOST_ASIO_DECL bad_executor() BOOST_ASIO_NOEXCEPT;
+
+  /// Obtain message associated with exception.
+  BOOST_ASIO_DECL virtual const char* what() const
+    BOOST_ASIO_NOEXCEPT_OR_NOTHROW;
+};
+
+/// Polymorphic wrapper for executors.
+class executor
+{
+public:
+  /// Default constructor.
+  executor() BOOST_ASIO_NOEXCEPT
+    : impl_(0)
+  {
+  }
+
+  /// Construct from nullptr.
+  executor(nullptr_t) BOOST_ASIO_NOEXCEPT
+    : impl_(0)
+  {
+  }
+
+  /// Copy constructor.
+  executor(const executor& other) BOOST_ASIO_NOEXCEPT
+    : impl_(other.clone())
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move constructor.
+  executor(executor&& other) BOOST_ASIO_NOEXCEPT
+    : impl_(other.impl_)
+  {
+    other.impl_ = 0;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Construct a polymorphic wrapper for the specified executor.
+  template <typename Executor>
+  executor(Executor e);
+
+  /// Allocator-aware constructor to create a polymorphic wrapper for the
+  /// specified executor.
+  template <typename Executor, typename Allocator>
+  executor(allocator_arg_t, const Allocator& a, Executor e);
+
+  /// Destructor.
+  ~executor()
+  {
+    destroy();
+  }
+
+  /// Assignment operator.
+  executor& operator=(const executor& other) BOOST_ASIO_NOEXCEPT
+  {
+    destroy();
+    impl_ = other.clone();
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  // Move assignment operator.
+  executor& operator=(executor&& other) BOOST_ASIO_NOEXCEPT
+  {
+    destroy();
+    impl_ = other.impl_;
+    other.impl_ = 0;
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Assignment operator for nullptr_t.
+  executor& operator=(nullptr_t) BOOST_ASIO_NOEXCEPT
+  {
+    destroy();
+    impl_ = 0;
+    return *this;
+  }
+
+  /// Assignment operator to create a polymorphic wrapper for the specified
+  /// executor.
+  template <typename Executor>
+  executor& operator=(BOOST_ASIO_MOVE_ARG(Executor) e) BOOST_ASIO_NOEXCEPT
+  {
+    executor tmp(BOOST_ASIO_MOVE_CAST(Executor)(e));
+    destroy();
+    impl_ = tmp.impl_;
+    tmp.impl_ = 0;
+    return *this;
+  }
+
+  /// Obtain the underlying execution context.
+  execution_context& context() const BOOST_ASIO_NOEXCEPT
+  {
+    return get_impl()->context();
+  }
+
+  /// Inform the executor that it has some outstanding work to do.
+  void on_work_started() const BOOST_ASIO_NOEXCEPT
+  {
+    get_impl()->on_work_started();
+  }
+
+  /// Inform the executor that some work is no longer outstanding.
+  void on_work_finished() const BOOST_ASIO_NOEXCEPT
+  {
+    get_impl()->on_work_finished();
+  }
+
+  /// Request the executor to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object is executed according to the rules of the
+   * target executor object.
+   *
+   * @param f The function object to be called. The executor will make a copy
+   * of the handler object as required. The function signature of the function
+   * object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the executor to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object is executed according to the rules of the
+   * target executor object.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the executor to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object is executed according to the rules of the
+   * target executor object.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  struct unspecified_bool_type_t {};
+  typedef void (*unspecified_bool_type)(unspecified_bool_type_t);
+  static void unspecified_bool_true(unspecified_bool_type_t) {}
+
+  /// Operator to test if the executor contains a valid target.
+  operator unspecified_bool_type() const BOOST_ASIO_NOEXCEPT
+  {
+    return impl_ ? &executor::unspecified_bool_true : 0;
+  }
+
+  /// Obtain type information for the target executor object.
+  /**
+   * @returns If @c *this has a target type of type @c T, <tt>typeid(T)</tt>;
+   * otherwise, <tt>typeid(void)</tt>.
+   */
+#if !defined(BOOST_ASIO_NO_TYPEID) || defined(GENERATING_DOCUMENTATION)
+  const std::type_info& target_type() const BOOST_ASIO_NOEXCEPT
+  {
+    return impl_ ? impl_->target_type() : typeid(void);
+  }
+#else // !defined(BOOST_ASIO_NO_TYPEID) || defined(GENERATING_DOCUMENTATION)
+  const void* target_type() const BOOST_ASIO_NOEXCEPT
+  {
+    return impl_ ? impl_->target_type() : 0;
+  }
+#endif // !defined(BOOST_ASIO_NO_TYPEID) || defined(GENERATING_DOCUMENTATION)
+
+  /// Obtain a pointer to the target executor object.
+  /**
+   * @returns If <tt>target_type() == typeid(T)</tt>, a pointer to the stored
+   * executor target; otherwise, a null pointer.
+   */
+  template <typename Executor>
+  Executor* target() BOOST_ASIO_NOEXCEPT;
+
+  /// Obtain a pointer to the target executor object.
+  /**
+   * @returns If <tt>target_type() == typeid(T)</tt>, a pointer to the stored
+   * executor target; otherwise, a null pointer.
+   */
+  template <typename Executor>
+  const Executor* target() const BOOST_ASIO_NOEXCEPT;
+
+  /// Compare two executors for equality.
+  friend bool operator==(const executor& a,
+      const executor& b) BOOST_ASIO_NOEXCEPT
+  {
+    if (a.impl_ == b.impl_)
+      return true;
+    if (!a.impl_ || !b.impl_)
+      return false;
+    return a.impl_->equals(b.impl_);
+  }
+
+  /// Compare two executors for inequality.
+  friend bool operator!=(const executor& a,
+      const executor& b) BOOST_ASIO_NOEXCEPT
+  {
+    return !(a == b);
+  }
+
+private:
+#if !defined(GENERATING_DOCUMENTATION)
+  class function;
+  template <typename, typename> class impl;
+
+#if !defined(BOOST_ASIO_NO_TYPEID)
+  typedef const std::type_info& type_id_result_type;
+#else // !defined(BOOST_ASIO_NO_TYPEID)
+  typedef const void* type_id_result_type;
+#endif // !defined(BOOST_ASIO_NO_TYPEID)
+
+  template <typename T>
+  static type_id_result_type type_id()
+  {
+#if !defined(BOOST_ASIO_NO_TYPEID)
+    return typeid(T);
+#else // !defined(BOOST_ASIO_NO_TYPEID)
+    static int unique_id;
+    return &unique_id;
+#endif // !defined(BOOST_ASIO_NO_TYPEID)
+  }
+
+  // Base class for all polymorphic executor implementations.
+  class impl_base
+  {
+  public:
+    virtual impl_base* clone() const BOOST_ASIO_NOEXCEPT = 0;
+    virtual void destroy() BOOST_ASIO_NOEXCEPT = 0;
+    virtual execution_context& context() BOOST_ASIO_NOEXCEPT = 0;
+    virtual void on_work_started() BOOST_ASIO_NOEXCEPT = 0;
+    virtual void on_work_finished() BOOST_ASIO_NOEXCEPT = 0;
+    virtual void dispatch(BOOST_ASIO_MOVE_ARG(function)) = 0;
+    virtual void post(BOOST_ASIO_MOVE_ARG(function)) = 0;
+    virtual void defer(BOOST_ASIO_MOVE_ARG(function)) = 0;
+    virtual type_id_result_type target_type() const BOOST_ASIO_NOEXCEPT = 0;
+    virtual void* target() BOOST_ASIO_NOEXCEPT = 0;
+    virtual const void* target() const BOOST_ASIO_NOEXCEPT = 0;
+    virtual bool equals(const impl_base* e) const BOOST_ASIO_NOEXCEPT = 0;
+
+  protected:
+    impl_base(bool fast_dispatch) : fast_dispatch_(fast_dispatch) {}
+    virtual ~impl_base() {}
+
+  private:
+    friend class executor;
+    const bool fast_dispatch_;
+  };
+
+  // Helper function to check and return the implementation pointer.
+  impl_base* get_impl() const
+  {
+    if (!impl_)
+    {
+      bad_executor ex;
+      boost::asio::detail::throw_exception(ex);
+    }
+    return impl_;
+  }
+
+  // Helper function to clone another implementation.
+  impl_base* clone() const BOOST_ASIO_NOEXCEPT
+  {
+    return impl_ ? impl_->clone() : 0;
+  }
+
+  // Helper function to destroy an implementation.
+  void destroy() BOOST_ASIO_NOEXCEPT
+  {
+    if (impl_)
+      impl_->destroy();
+  }
+
+  impl_base* impl_;
+#endif // !defined(GENERATING_DOCUMENTATION)
+};
+
+} // namespace asio
+} // namespace boost
+
+BOOST_ASIO_USES_ALLOCATOR(boost::asio::executor)
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/executor.hpp>
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/impl/executor.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+#endif // BOOST_ASIO_EXECUTOR_HPP
diff --git a/include/boost/asio/executor_work_guard.hpp b/include/boost/asio/executor_work_guard.hpp
new file mode 100644
index 0000000000..a5e2276b88
--- /dev/null
+++ b/include/boost/asio/executor_work_guard.hpp
@@ -0,0 +1,171 @@
+//
+// executor_work_guard.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_EXECUTOR_WORK_GUARD_HPP
+#define BOOST_ASIO_EXECUTOR_WORK_GUARD_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/is_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// An object of type @c executor_work_guard controls ownership of executor work
+/// within a scope.
+template <typename Executor>
+class executor_work_guard
+{
+public:
+  /// The underlying executor type.
+  typedef Executor executor_type;
+
+  /// Constructs a @c executor_work_guard object for the specified executor.
+  /**
+   * Stores a copy of @c e and calls <tt>on_work_started()</tt> on it.
+   */
+  explicit executor_work_guard(const executor_type& e) BOOST_ASIO_NOEXCEPT
+    : executor_(e),
+      owns_(true)
+  {
+    executor_.on_work_started();
+  }
+
+  /// Copy constructor.
+  executor_work_guard(const executor_work_guard& other) BOOST_ASIO_NOEXCEPT
+    : executor_(other.executor_),
+      owns_(other.owns_)
+  {
+    if (owns_)
+      executor_.on_work_started();
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move constructor.
+  executor_work_guard(executor_work_guard&& other)
+    : executor_(BOOST_ASIO_MOVE_CAST(Executor)(other.executor_)),
+      owns_(other.owns_)
+  {
+    other.owns_ = false;
+  }
+#endif //  defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Destructor.
+  /**
+   * Unless the object has already been reset, or is in a moved-from state,
+   * calls <tt>on_work_finished()</tt> on the stored executor.
+   */
+  ~executor_work_guard()
+  {
+    if (owns_)
+      executor_.on_work_finished();
+  }
+
+  /// Obtain the associated executor.
+  executor_type get_executor() const BOOST_ASIO_NOEXCEPT
+  {
+    return executor_;
+  }
+
+  /// Whether the executor_work_guard object owns some outstanding work.
+  bool owns_work() const BOOST_ASIO_NOEXCEPT
+  {
+    return owns_;
+  }
+
+  /// Indicate that the work is no longer outstanding.
+  /*
+   * Unless the object has already been reset, or is in a moved-from state,
+   * calls <tt>on_work_finished()</tt> on the stored executor.
+   */
+  void reset() BOOST_ASIO_NOEXCEPT
+  {
+    if (owns_)
+    {
+      executor_.on_work_finished();
+      owns_ = false;
+    }
+  }
+
+private:
+  // Disallow assignment.
+  executor_work_guard& operator=(const executor_work_guard&);
+
+  executor_type executor_;
+  bool owns_;
+};
+
+/// Create an @ref executor_work_guard object.
+template <typename Executor>
+inline executor_work_guard<Executor> make_work_guard(const Executor& ex,
+    typename enable_if<is_executor<Executor>::value>::type* = 0)
+{
+  return executor_work_guard<Executor>(ex);
+}
+
+/// Create an @ref executor_work_guard object.
+template <typename ExecutionContext>
+inline executor_work_guard<typename ExecutionContext::executor_type>
+make_work_guard(ExecutionContext& ctx,
+    typename enable_if<
+      is_convertible<ExecutionContext&, execution_context&>::value>::type* = 0)
+{
+  return executor_work_guard<typename ExecutionContext::executor_type>(
+      ctx.get_executor());
+}
+
+/// Create an @ref executor_work_guard object.
+template <typename T>
+inline executor_work_guard<typename associated_executor<T>::type>
+make_work_guard(const T& t,
+    typename enable_if<!is_executor<T>::value &&
+      !is_convertible<T&, execution_context&>::value>::type* = 0)
+{
+  return executor_work_guard<typename associated_executor<T>::type>(
+      associated_executor<T>::get(t));
+}
+
+/// Create an @ref executor_work_guard object.
+template <typename T, typename Executor>
+inline executor_work_guard<typename associated_executor<T, Executor>::type>
+make_work_guard(const T& t, const Executor& ex,
+    typename enable_if<is_executor<Executor>::value>::type* = 0)
+{
+  return executor_work_guard<typename associated_executor<T, Executor>::type>(
+      associated_executor<T, Executor>::get(t, ex));
+}
+
+/// Create an @ref executor_work_guard object.
+template <typename T, typename ExecutionContext>
+inline executor_work_guard<typename associated_executor<T,
+  typename ExecutionContext::executor_type>::type>
+make_work_guard(const T& t, ExecutionContext& ctx,
+    typename enable_if<!is_executor<T>::value &&
+      !is_convertible<T&, execution_context&>::value>::type* = 0)
+{
+  return executor_work_guard<typename associated_executor<T,
+    typename ExecutionContext::executor_type>::type>(
+      associated_executor<T, typename ExecutionContext::executor_type>::get(
+        t, ctx.get_executor()));
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_EXECUTOR_WORK_GUARD_HPP
diff --git a/include/boost/asio/handler_invoke_hook.hpp b/include/boost/asio/handler_invoke_hook.hpp
index 6605d87499..f698c2f863 100644
--- a/include/boost/asio/handler_invoke_hook.hpp
+++ b/include/boost/asio/handler_invoke_hook.hpp
@@ -27,12 +27,12 @@ namespace asio {
  * @brief Default invoke function for handlers.
  *
  * Completion handlers for asynchronous operations are invoked by the
- * io_service associated with the corresponding object (e.g. a socket or
+ * io_context associated with the corresponding object (e.g. a socket or
  * deadline_timer). Certain guarantees are made on when the handler may be
  * invoked, in particular that a handler can only be invoked from a thread that
- * is currently calling @c run() on the corresponding io_service object.
+ * is currently calling @c run() on the corresponding io_context object.
  * Handlers may subsequently be invoked through other objects (such as
- * io_service::strand objects) that provide additional guarantees.
+ * io_context::strand objects) that provide additional guarantees.
  *
  * When asynchronous operations are composed from other asynchronous
  * operations, all intermediate handlers should be invoked using the same
diff --git a/include/boost/asio/handler_type.hpp b/include/boost/asio/handler_type.hpp
index 11e97e3ea0..97187574b6 100644
--- a/include/boost/asio/handler_type.hpp
+++ b/include/boost/asio/handler_type.hpp
@@ -16,99 +16,37 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
-/// Default handler type traits provided for all handlers.
+/// (Deprecated: Use two-parameter version of async_result.) Default handler
+/// type traits provided for all completion token types.
 /**
  * The handler_type traits class is used for determining the concrete handler
  * type to be used for an asynchronous operation. It allows the handler type to
  * be determined at the point where the specific completion handler signature
  * is known.
  *
- * This template may be specialised for user-defined handler types.
+ * This template may be specialised for user-defined completion token types.
  */
-template <typename Handler, typename Signature>
+template <typename CompletionToken, typename Signature, typename = void>
 struct handler_type
 {
   /// The handler type for the specific signature.
-  typedef Handler type;
+  typedef typename conditional<
+    is_same<CompletionToken, typename decay<CompletionToken>::type>::value,
+    decay<CompletionToken>,
+    handler_type<typename decay<CompletionToken>::type, Signature>
+  >::type::type type;
 };
 
-#if !defined(GENERATING_DOCUMENTATION)
-
-template <typename Handler, typename Signature>
-struct handler_type<const Handler, Signature>
-  : handler_type<Handler, Signature> {};
-
-template <typename Handler, typename Signature>
-struct handler_type<volatile Handler, Signature>
-  : handler_type<Handler, Signature> {};
-
-template <typename Handler, typename Signature>
-struct handler_type<const volatile Handler, Signature>
-  : handler_type<Handler, Signature> {};
-
-template <typename Handler, typename Signature>
-struct handler_type<const Handler&, Signature>
-  : handler_type<Handler, Signature> {};
-
-template <typename Handler, typename Signature>
-struct handler_type<volatile Handler&, Signature>
-  : handler_type<Handler, Signature> {};
-
-template <typename Handler, typename Signature>
-struct handler_type<const volatile Handler&, Signature>
-  : handler_type<Handler, Signature> {};
-
-template <typename Handler, typename Signature>
-struct handler_type<Handler&, Signature>
-  : handler_type<Handler, Signature> {};
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-template <typename Handler, typename Signature>
-struct handler_type<Handler&&, Signature>
-  : handler_type<Handler, Signature> {};
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-template <typename ReturnType, typename Signature>
-struct handler_type<ReturnType(), Signature>
-  : handler_type<ReturnType(*)(), Signature> {};
-
-template <typename ReturnType, typename Arg1, typename Signature>
-struct handler_type<ReturnType(Arg1), Signature>
-  : handler_type<ReturnType(*)(Arg1), Signature> {};
-
-template <typename ReturnType, typename Arg1, typename Arg2, typename Signature>
-struct handler_type<ReturnType(Arg1, Arg2), Signature>
-  : handler_type<ReturnType(*)(Arg1, Arg2), Signature> {};
-
-template <typename ReturnType, typename Arg1, typename Arg2, typename Arg3,
-    typename Signature>
-struct handler_type<ReturnType(Arg1, Arg2, Arg3), Signature>
-  : handler_type<ReturnType(*)(Arg1, Arg2, Arg3), Signature> {};
-
-template <typename ReturnType, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4, typename Signature>
-struct handler_type<ReturnType(Arg1, Arg2, Arg3, Arg4), Signature>
-  : handler_type<ReturnType(*)(Arg1, Arg2, Arg3, Arg4), Signature> {};
-
-template <typename ReturnType, typename Arg1, typename Arg2, typename Arg3,
-    typename Arg4, typename Arg5, typename Signature>
-struct handler_type<ReturnType(Arg1, Arg2, Arg3, Arg4, Arg5), Signature>
-  : handler_type<ReturnType(*)(Arg1, Arg2, Arg3, Arg4, Arg5), Signature> {};
-
-#endif // !defined(GENERATING_DOCUMENTATION)
-
 } // namespace asio
 } // namespace boost
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#define BOOST_ASIO_HANDLER_TYPE(h, sig) \
-  typename handler_type<h, sig>::type
-
 #endif // BOOST_ASIO_HANDLER_TYPE_HPP
diff --git a/include/boost/asio/high_resolution_timer.hpp b/include/boost/asio/high_resolution_timer.hpp
index 5d6cef0296..3cd57714ee 100644
--- a/include/boost/asio/high_resolution_timer.hpp
+++ b/include/boost/asio/high_resolution_timer.hpp
@@ -17,22 +17,14 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_HAS_STD_CHRONO) \
-  || defined(BOOST_ASIO_HAS_BOOST_CHRONO) \
-  || defined(GENERATING_DOCUMENTATION)
-
-#if defined(BOOST_ASIO_HAS_STD_CHRONO)
-# include <chrono>
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-# include <boost/chrono/system_clocks.hpp>
-#endif
+#if defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
 
 #include <boost/asio/basic_waitable_timer.hpp>
+#include <boost/asio/detail/chrono.hpp>
 
 namespace boost {
 namespace asio {
 
-#if defined(GENERATING_DOCUMENTATION)
 /// Typedef for a timer based on the high resolution clock.
 /**
  * This typedef uses the C++11 @c &lt;chrono&gt; standard library facility, if
@@ -45,21 +37,10 @@ namespace asio {
 typedef basic_waitable_timer<
     chrono::high_resolution_clock>
   high_resolution_timer;
-#elif defined(BOOST_ASIO_HAS_STD_CHRONO)
-typedef basic_waitable_timer<
-    std::chrono::high_resolution_clock>
-  high_resolution_timer;
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-typedef basic_waitable_timer<
-    boost::chrono::high_resolution_clock>
-  high_resolution_timer;
-#endif
 
 } // namespace asio
 } // namespace boost
 
-#endif // defined(BOOST_ASIO_HAS_STD_CHRONO) 
-       //   || defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-       //   || defined(GENERATING_DOCUMENTATION)
+#endif // defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
 
 #endif // BOOST_ASIO_HIGH_RESOLUTION_TIMER_HPP
diff --git a/include/boost/asio/impl/buffered_read_stream.hpp b/include/boost/asio/impl/buffered_read_stream.hpp
index 082ed0338b..0813db4fce 100644
--- a/include/boost/asio/impl/buffered_read_stream.hpp
+++ b/include/boost/asio/impl/buffered_read_stream.hpp
@@ -15,6 +15,8 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_cont_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
@@ -138,6 +140,36 @@ namespace detail
   }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::buffered_fill_handler<ReadHandler>, Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(const detail::buffered_fill_handler<ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::buffered_fill_handler<ReadHandler>, Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(const detail::buffered_fill_handler<ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename Stream>
 template <typename ReadHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
@@ -149,9 +181,8 @@ buffered_read_stream<Stream>::async_fill(
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   std::size_t previous_size = storage_.size();
   storage_.resize(storage_.capacity());
@@ -161,7 +192,7 @@ buffered_read_stream<Stream>::async_fill(
         storage_.size() - previous_size),
       detail::buffered_fill_handler<BOOST_ASIO_HANDLER_TYPE(
         ReadHandler, void (boost::system::error_code, std::size_t))>(
-        storage_, previous_size, init.handler));
+        storage_, previous_size, init.completion_handler));
 
   return init.result.get();
 }
@@ -171,7 +202,8 @@ template <typename MutableBufferSequence>
 std::size_t buffered_read_stream<Stream>::read_some(
     const MutableBufferSequence& buffers)
 {
-  if (boost::asio::buffer_size(buffers) == 0)
+  using boost::asio::buffer_size;
+  if (buffer_size(buffers) == 0)
     return 0;
 
   if (storage_.empty())
@@ -187,7 +219,8 @@ std::size_t buffered_read_stream<Stream>::read_some(
 {
   ec = boost::system::error_code();
 
-  if (boost::asio::buffer_size(buffers) == 0)
+  using boost::asio::buffer_size;
+  if (buffer_size(buffers) == 0)
     return 0;
 
   if (storage_.empty() && !this->fill(ec))
@@ -206,7 +239,7 @@ namespace detail
         const MutableBufferSequence& buffers, ReadHandler& handler)
       : storage_(storage),
         buffers_(buffers),
-        handler_(handler)
+        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
     {
     }
 
@@ -296,6 +329,44 @@ namespace detail
   }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename MutableBufferSequence,
+    typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::buffered_read_some_handler<MutableBufferSequence, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::buffered_read_some_handler<
+        MutableBufferSequence, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename MutableBufferSequence,
+    typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::buffered_read_some_handler<MutableBufferSequence, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::buffered_read_some_handler<
+        MutableBufferSequence, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename Stream>
 template <typename MutableBufferSequence, typename ReadHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
@@ -308,24 +379,24 @@ buffered_read_stream<Stream>::async_read_some(
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  if (boost::asio::buffer_size(buffers) == 0 || !storage_.empty())
+  using boost::asio::buffer_size;
+  if (buffer_size(buffers) == 0 || !storage_.empty())
   {
-    next_layer_.async_read_some(boost::asio::mutable_buffers_1(0, 0),
+    next_layer_.async_read_some(BOOST_ASIO_MUTABLE_BUFFER(0, 0),
         detail::buffered_read_some_handler<
           MutableBufferSequence, BOOST_ASIO_HANDLER_TYPE(
             ReadHandler, void (boost::system::error_code, std::size_t))>(
-            storage_, buffers, init.handler));
+            storage_, buffers, init.completion_handler));
   }
   else
   {
     this->async_fill(detail::buffered_read_some_handler<
           MutableBufferSequence, BOOST_ASIO_HANDLER_TYPE(
             ReadHandler, void (boost::system::error_code, std::size_t))>(
-            storage_, buffers, init.handler));
+            storage_, buffers, init.completion_handler));
   }
 
   return init.result.get();
diff --git a/include/boost/asio/impl/buffered_write_stream.hpp b/include/boost/asio/impl/buffered_write_stream.hpp
index 22585eb6ce..baaa694538 100644
--- a/include/boost/asio/impl/buffered_write_stream.hpp
+++ b/include/boost/asio/impl/buffered_write_stream.hpp
@@ -15,6 +15,8 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_cont_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
@@ -53,7 +55,7 @@ namespace detail
     buffered_flush_handler(detail::buffered_stream_storage& storage,
         WriteHandler& handler)
       : storage_(storage),
-        handler_(handler)
+        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
     {
     }
 
@@ -122,7 +124,37 @@ namespace detail
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
-}
+} // namespace detail
+
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename WriteHandler, typename Allocator>
+struct associated_allocator<
+    detail::buffered_flush_handler<WriteHandler>, Allocator>
+{
+  typedef typename associated_allocator<WriteHandler, Allocator>::type type;
+
+  static type get(const detail::buffered_flush_handler<WriteHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<WriteHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename WriteHandler, typename Executor>
+struct associated_executor<
+    detail::buffered_flush_handler<WriteHandler>, Executor>
+{
+  typedef typename associated_executor<WriteHandler, Executor>::type type;
+
+  static type get(const detail::buffered_flush_handler<WriteHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<WriteHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
 
 template <typename Stream>
 template <typename WriteHandler>
@@ -135,14 +167,13 @@ buffered_write_stream<Stream>::async_flush(
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   async_write(next_layer_, buffer(storage_.data(), storage_.size()),
       detail::buffered_flush_handler<BOOST_ASIO_HANDLER_TYPE(
         WriteHandler, void (boost::system::error_code, std::size_t))>(
-        storage_, init.handler));
+        storage_, init.completion_handler));
 
   return init.result.get();
 }
@@ -152,7 +183,8 @@ template <typename ConstBufferSequence>
 std::size_t buffered_write_stream<Stream>::write_some(
     const ConstBufferSequence& buffers)
 {
-  if (boost::asio::buffer_size(buffers) == 0)
+  using boost::asio::buffer_size;
+  if (buffer_size(buffers) == 0)
     return 0;
 
   if (storage_.size() == storage_.capacity())
@@ -168,7 +200,8 @@ std::size_t buffered_write_stream<Stream>::write_some(
 {
   ec = boost::system::error_code();
 
-  if (boost::asio::buffer_size(buffers) == 0)
+  using boost::asio::buffer_size;
+  if (buffer_size(buffers) == 0)
     return 0;
 
   if (storage_.size() == storage_.capacity() && !flush(ec))
@@ -187,7 +220,7 @@ namespace detail
         const ConstBufferSequence& buffers, WriteHandler& handler)
       : storage_(storage),
         buffers_(buffers),
-        handler_(handler)
+        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
     {
     }
 
@@ -216,9 +249,10 @@ namespace detail
       }
       else
       {
+        using boost::asio::buffer_size;
         std::size_t orig_size = storage_.size();
         std::size_t space_avail = storage_.capacity() - orig_size;
-        std::size_t bytes_avail = boost::asio::buffer_size(buffers_);
+        std::size_t bytes_avail = buffer_size(buffers_);
         std::size_t length = bytes_avail < space_avail
           ? bytes_avail : space_avail;
         storage_.resize(orig_size + length);
@@ -282,6 +316,44 @@ namespace detail
   }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename ConstBufferSequence,
+    typename WriteHandler, typename Allocator>
+struct associated_allocator<
+    detail::buffered_write_some_handler<ConstBufferSequence, WriteHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<WriteHandler, Allocator>::type type;
+
+  static type get(
+      const detail::buffered_write_some_handler<
+        ConstBufferSequence, WriteHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<WriteHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename ConstBufferSequence,
+    typename WriteHandler, typename Executor>
+struct associated_executor<
+    detail::buffered_write_some_handler<ConstBufferSequence, WriteHandler>,
+    Executor>
+{
+  typedef typename associated_executor<WriteHandler, Executor>::type type;
+
+  static type get(
+      const detail::buffered_write_some_handler<
+        ConstBufferSequence, WriteHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<WriteHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename Stream>
 template <typename ConstBufferSequence, typename WriteHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
@@ -294,25 +366,25 @@ buffered_write_stream<Stream>::async_write_some(
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  if (boost::asio::buffer_size(buffers) == 0
+  using boost::asio::buffer_size;
+  if (buffer_size(buffers) == 0
       || storage_.size() < storage_.capacity())
   {
-    next_layer_.async_write_some(boost::asio::const_buffers_1(0, 0),
+    next_layer_.async_write_some(BOOST_ASIO_CONST_BUFFER(0, 0),
         detail::buffered_write_some_handler<
           ConstBufferSequence, BOOST_ASIO_HANDLER_TYPE(
             WriteHandler, void (boost::system::error_code, std::size_t))>(
-            storage_, buffers, init.handler));
+            storage_, buffers, init.completion_handler));
   }
   else
   {
     this->async_flush(detail::buffered_write_some_handler<
           ConstBufferSequence, BOOST_ASIO_HANDLER_TYPE(
             WriteHandler, void (boost::system::error_code, std::size_t))>(
-            storage_, buffers, init.handler));
+            storage_, buffers, init.completion_handler));
   }
 
   return init.result.get();
@@ -323,9 +395,10 @@ template <typename ConstBufferSequence>
 std::size_t buffered_write_stream<Stream>::copy(
     const ConstBufferSequence& buffers)
 {
+  using boost::asio::buffer_size;
   std::size_t orig_size = storage_.size();
   std::size_t space_avail = storage_.capacity() - orig_size;
-  std::size_t bytes_avail = boost::asio::buffer_size(buffers);
+  std::size_t bytes_avail = buffer_size(buffers);
   std::size_t length = bytes_avail < space_avail ? bytes_avail : space_avail;
   storage_.resize(orig_size + length);
   return boost::asio::buffer_copy(
diff --git a/include/boost/asio/impl/connect.hpp b/include/boost/asio/impl/connect.hpp
index ba587eca02..234e53dd9f 100644
--- a/include/boost/asio/impl/connect.hpp
+++ b/include/boost/asio/impl/connect.hpp
@@ -15,14 +15,17 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <algorithm>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
-#include <boost/asio/detail/consuming_buffers.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_cont_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
+#include <boost/asio/post.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -33,16 +36,44 @@ namespace detail
 {
   struct default_connect_condition
   {
-    template <typename Iterator>
-    Iterator operator()(const boost::system::error_code&, Iterator next)
+    template <typename Endpoint>
+    bool operator()(const boost::system::error_code&, const Endpoint&)
     {
-      return next;
+      return true;
     }
   };
 }
 
-template <typename Protocol, typename SocketService, typename Iterator>
-Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename EndpointSequence>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type*)
+{
+  boost::system::error_code ec;
+  typename Protocol::endpoint result = connect(s, endpoints, ec);
+  boost::asio::detail::throw_error(ec, "connect");
+  return result;
+}
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename EndpointSequence>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, boost::system::error_code& ec,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type*)
+{
+  typename EndpointSequence::iterator iter = connect(
+      s, endpoints.begin(), endpoints.end(),
+      detail::default_connect_condition(), ec);
+  return ec ? typename Protocol::endpoint() : *iter;
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s, Iterator begin,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type*)
 {
   boost::system::error_code ec;
   Iterator result = connect(s, begin, ec);
@@ -50,15 +81,17 @@ Iterator connect(basic_socket<Protocol, SocketService>& s, Iterator begin)
   return result;
 }
 
-template <typename Protocol, typename SocketService, typename Iterator>
-inline Iterator connect(basic_socket<Protocol, SocketService>& s,
-    Iterator begin, boost::system::error_code& ec)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+inline Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    Iterator begin, boost::system::error_code& ec,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type*)
 {
   return connect(s, begin, Iterator(), detail::default_connect_condition(), ec);
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-template <typename Protocol, typename SocketService, typename Iterator>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end)
 {
   boost::system::error_code ec;
@@ -67,17 +100,48 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
   return result;
 }
 
-template <typename Protocol, typename SocketService, typename Iterator>
-inline Iterator connect(basic_socket<Protocol, SocketService>& s,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator>
+inline Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end, boost::system::error_code& ec)
 {
   return connect(s, begin, end, detail::default_connect_condition(), ec);
 }
 
-template <typename Protocol, typename SocketService,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type*)
+{
+  boost::system::error_code ec;
+  typename Protocol::endpoint result = connect(
+      s, endpoints, connect_condition, ec);
+  boost::asio::detail::throw_error(ec, "connect");
+  return result;
+}
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition>
+typename Protocol::endpoint connect(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    boost::system::error_code& ec,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type*)
+{
+  typename EndpointSequence::iterator iter = connect(
+      s, endpoints.begin(), endpoints.end(), connect_condition, ec);
+  return ec ? typename Protocol::endpoint() : *iter;
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
     typename Iterator, typename ConnectCondition>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
-    Iterator begin, ConnectCondition connect_condition)
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    Iterator begin, ConnectCondition connect_condition,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type*)
 {
   boost::system::error_code ec;
   Iterator result = connect(s, begin, connect_condition, ec);
@@ -85,18 +149,20 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
   return result;
 }
 
-template <typename Protocol, typename SocketService,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
     typename Iterator, typename ConnectCondition>
-inline Iterator connect(basic_socket<Protocol, SocketService>& s,
+inline Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, ConnectCondition connect_condition,
-    boost::system::error_code& ec)
+    boost::system::error_code& ec,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type*)
 {
   return connect(s, begin, Iterator(), connect_condition, ec);
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-template <typename Protocol, typename SocketService,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
     typename Iterator, typename ConnectCondition>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end, ConnectCondition connect_condition)
 {
   boost::system::error_code ec;
@@ -105,9 +171,9 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
   return result;
 }
 
-template <typename Protocol, typename SocketService,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
     typename Iterator, typename ConnectCondition>
-Iterator connect(basic_socket<Protocol, SocketService>& s,
+Iterator connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end, ConnectCondition connect_condition,
     boost::system::error_code& ec)
 {
@@ -115,16 +181,13 @@ Iterator connect(basic_socket<Protocol, SocketService>& s,
 
   for (Iterator iter = begin; iter != end; ++iter)
   {
-    iter = connect_condition(ec, iter);
-    if (iter != end)
+    if (connect_condition(ec, iter))
     {
       s.close(ec);
       s.connect(*iter, ec);
       if (!ec)
         return iter;
     }
-    else
-      break;
   }
 
   if (!ec)
@@ -146,12 +209,11 @@ namespace detail
     {
     }
 
-    template <typename Iterator>
-    void check_condition(const boost::system::error_code& ec,
-        Iterator& iter, Iterator& end)
+    template <typename Endpoint>
+    bool check_condition(const boost::system::error_code& ec,
+        const Endpoint& endpoint)
     {
-      if (iter != end)
-        iter = connect_condition_(ec, static_cast<const Iterator&>(iter));
+      return connect_condition_(ec, endpoint);
     }
 
   private:
@@ -168,32 +230,193 @@ namespace detail
     {
     }
 
-    template <typename Iterator>
-    void check_condition(const boost::system::error_code&, Iterator&, Iterator&)
+    template <typename Endpoint>
+    bool check_condition(const boost::system::error_code&, const Endpoint&)
     {
+      return true;
     }
   };
 
-  template <typename Protocol, typename SocketService, typename Iterator,
-      typename ConnectCondition, typename ComposedConnectHandler>
-  class connect_op : base_from_connect_condition<ConnectCondition>
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+      typename EndpointSequence, typename ConnectCondition,
+      typename RangeConnectHandler>
+  class range_connect_op : base_from_connect_condition<ConnectCondition>
   {
   public:
-    connect_op(basic_socket<Protocol, SocketService>& sock,
+    range_connect_op(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& sock,
+        const EndpointSequence& endpoints,
+        const ConnectCondition& connect_condition,
+        RangeConnectHandler& handler)
+      : base_from_connect_condition<ConnectCondition>(connect_condition),
+        socket_(sock),
+        endpoints_(endpoints),
+        index_(0),
+        start_(0),
+        handler_(BOOST_ASIO_MOVE_CAST(RangeConnectHandler)(handler))
+    {
+    }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    range_connect_op(const range_connect_op& other)
+      : base_from_connect_condition<ConnectCondition>(other),
+        socket_(other.socket_),
+        endpoints_(other.endpoints_),
+        index_(other.index_),
+        start_(other.start_),
+        handler_(other.handler_)
+    {
+    }
+
+    range_connect_op(range_connect_op&& other)
+      : base_from_connect_condition<ConnectCondition>(other),
+        socket_(other.socket_),
+        endpoints_(other.endpoints_),
+        index_(other.index_),
+        start_(other.start_),
+        handler_(BOOST_ASIO_MOVE_CAST(RangeConnectHandler)(other.handler_))
+    {
+    }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+    void operator()(boost::system::error_code ec, int start = 0)
+    {
+      typename EndpointSequence::iterator iter = endpoints_.begin();
+      std::advance(iter, index_);
+      typename EndpointSequence::iterator end = endpoints_.end();
+
+      switch (start_ = start)
+      {
+        case 1:
+        for (;;)
+        {
+          for (; iter != end; ++iter, ++index_)
+            if (this->check_condition(ec, *iter))
+              break;
+
+          if (iter != end)
+          {
+            socket_.close(ec);
+            socket_.async_connect(*iter,
+                BOOST_ASIO_MOVE_CAST(range_connect_op)(*this));
+            return;
+          }
+
+          if (start)
+          {
+            ec = boost::asio::error::not_found;
+            boost::asio::post(socket_.get_executor(),
+                detail::bind_handler(
+                  BOOST_ASIO_MOVE_CAST(range_connect_op)(*this), ec));
+            return;
+          }
+
+          default:
+
+          if (iter == end)
+            break;
+
+          if (!socket_.is_open())
+          {
+            ec = boost::asio::error::operation_aborted;
+            break;
+          }
+
+          if (!ec)
+            break;
+
+          ++iter;
+          ++index_;
+        }
+
+        handler_(static_cast<const boost::system::error_code&>(ec),
+            static_cast<const typename Protocol::endpoint&>(
+              ec || iter == end ? typename Protocol::endpoint() : *iter));
+      }
+    }
+
+  //private:
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket_;
+    EndpointSequence endpoints_;
+    std::size_t index_;
+    int start_;
+    RangeConnectHandler handler_;
+  };
+
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+      typename EndpointSequence, typename ConnectCondition,
+      typename RangeConnectHandler>
+  inline void* asio_handler_allocate(std::size_t size,
+      range_connect_op<Protocol BOOST_ASIO_SVC_TARG, EndpointSequence,
+        ConnectCondition, RangeConnectHandler>* this_handler)
+  {
+    return boost_asio_handler_alloc_helpers::allocate(
+        size, this_handler->handler_);
+  }
+
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+      typename EndpointSequence, typename ConnectCondition,
+      typename RangeConnectHandler>
+  inline void asio_handler_deallocate(void* pointer, std::size_t size,
+      range_connect_op<Protocol BOOST_ASIO_SVC_TARG, EndpointSequence,
+        ConnectCondition, RangeConnectHandler>* this_handler)
+  {
+    boost_asio_handler_alloc_helpers::deallocate(
+        pointer, size, this_handler->handler_);
+  }
+
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+      typename EndpointSequence, typename ConnectCondition,
+      typename RangeConnectHandler>
+  inline bool asio_handler_is_continuation(
+      range_connect_op<Protocol BOOST_ASIO_SVC_TARG, EndpointSequence,
+        ConnectCondition, RangeConnectHandler>* this_handler)
+  {
+    return boost_asio_handler_cont_helpers::is_continuation(
+        this_handler->handler_);
+  }
+
+  template <typename Function, typename Protocol
+      BOOST_ASIO_SVC_TPARAM, typename EndpointSequence,
+      typename ConnectCondition, typename RangeConnectHandler>
+  inline void asio_handler_invoke(Function& function,
+      range_connect_op<Protocol BOOST_ASIO_SVC_TARG, EndpointSequence,
+        ConnectCondition, RangeConnectHandler>* this_handler)
+  {
+    boost_asio_handler_invoke_helpers::invoke(
+        function, this_handler->handler_);
+  }
+
+  template <typename Function, typename Protocol
+      BOOST_ASIO_SVC_TPARAM, typename EndpointSequence,
+      typename ConnectCondition, typename RangeConnectHandler>
+  inline void asio_handler_invoke(const Function& function,
+      range_connect_op<Protocol BOOST_ASIO_SVC_TARG, EndpointSequence,
+        ConnectCondition, RangeConnectHandler>* this_handler)
+  {
+    boost_asio_handler_invoke_helpers::invoke(
+        function, this_handler->handler_);
+  }
+
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+      typename ConnectCondition, typename IteratorConnectHandler>
+  class iterator_connect_op : base_from_connect_condition<ConnectCondition>
+  {
+  public:
+    iterator_connect_op(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& sock,
         const Iterator& begin, const Iterator& end,
         const ConnectCondition& connect_condition,
-        ComposedConnectHandler& handler)
+        IteratorConnectHandler& handler)
       : base_from_connect_condition<ConnectCondition>(connect_condition),
         socket_(sock),
         iter_(begin),
         end_(end),
         start_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(ComposedConnectHandler)(handler))
+        handler_(BOOST_ASIO_MOVE_CAST(IteratorConnectHandler)(handler))
     {
     }
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    connect_op(const connect_op& other)
+    iterator_connect_op(const iterator_connect_op& other)
       : base_from_connect_condition<ConnectCondition>(other),
         socket_(other.socket_),
         iter_(other.iter_),
@@ -203,13 +426,13 @@ namespace detail
     {
     }
 
-    connect_op(connect_op&& other)
+    iterator_connect_op(iterator_connect_op&& other)
       : base_from_connect_condition<ConnectCondition>(other),
         socket_(other.socket_),
         iter_(other.iter_),
         end_(other.end_),
         start_(other.start_),
-        handler_(BOOST_ASIO_MOVE_CAST(ComposedConnectHandler)(other.handler_))
+        handler_(BOOST_ASIO_MOVE_CAST(IteratorConnectHandler)(other.handler_))
     {
     }
 #endif // defined(BOOST_ASIO_HAS_MOVE)
@@ -221,20 +444,24 @@ namespace detail
         case 1:
         for (;;)
         {
-          this->check_condition(ec, iter_, end_);
+          for (; iter_ != end_; ++iter_)
+            if (this->check_condition(ec, *iter_))
+              break;
 
           if (iter_ != end_)
           {
             socket_.close(ec);
             socket_.async_connect(*iter_,
-                BOOST_ASIO_MOVE_CAST(connect_op)(*this));
+                BOOST_ASIO_MOVE_CAST(iterator_connect_op)(*this));
             return;
           }
 
           if (start)
           {
             ec = boost::asio::error::not_found;
-            socket_.get_io_service().post(detail::bind_handler(*this, ec));
+            boost::asio::post(socket_.get_executor(),
+                detail::bind_handler(
+                  BOOST_ASIO_MOVE_CAST(iterator_connect_op)(*this), ec));
             return;
           }
 
@@ -261,164 +488,311 @@ namespace detail
     }
 
   //private:
-    basic_socket<Protocol, SocketService>& socket_;
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket_;
     Iterator iter_;
     Iterator end_;
     int start_;
-    ComposedConnectHandler handler_;
+    IteratorConnectHandler handler_;
   };
 
-  template <typename Protocol, typename SocketService, typename Iterator,
-      typename ConnectCondition, typename ComposedConnectHandler>
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+      typename ConnectCondition, typename IteratorConnectHandler>
   inline void* asio_handler_allocate(std::size_t size,
-      connect_op<Protocol, SocketService, Iterator,
-        ConnectCondition, ComposedConnectHandler>* this_handler)
+      iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
+        ConnectCondition, IteratorConnectHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename Protocol, typename SocketService, typename Iterator,
-      typename ConnectCondition, typename ComposedConnectHandler>
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+      typename ConnectCondition, typename IteratorConnectHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
-      connect_op<Protocol, SocketService, Iterator,
-        ConnectCondition, ComposedConnectHandler>* this_handler)
+      iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
+        ConnectCondition, IteratorConnectHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename Protocol, typename SocketService, typename Iterator,
-      typename ConnectCondition, typename ComposedConnectHandler>
+  template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+      typename ConnectCondition, typename IteratorConnectHandler>
   inline bool asio_handler_is_continuation(
-      connect_op<Protocol, SocketService, Iterator,
-        ConnectCondition, ComposedConnectHandler>* this_handler)
+      iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
+        ConnectCondition, IteratorConnectHandler>* this_handler)
   {
     return boost_asio_handler_cont_helpers::is_continuation(
         this_handler->handler_);
   }
 
-  template <typename Function, typename Protocol,
-      typename SocketService, typename Iterator,
-      typename ConnectCondition, typename ComposedConnectHandler>
+  template <typename Function, typename Protocol
+      BOOST_ASIO_SVC_TPARAM, typename Iterator,
+      typename ConnectCondition, typename IteratorConnectHandler>
   inline void asio_handler_invoke(Function& function,
-      connect_op<Protocol, SocketService, Iterator,
-        ConnectCondition, ComposedConnectHandler>* this_handler)
+      iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
+        ConnectCondition, IteratorConnectHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
-  template <typename Function, typename Protocol,
-      typename SocketService, typename Iterator,
-      typename ConnectCondition, typename ComposedConnectHandler>
+  template <typename Function, typename Protocol
+      BOOST_ASIO_SVC_TPARAM, typename Iterator,
+      typename ConnectCondition, typename IteratorConnectHandler>
   inline void asio_handler_invoke(const Function& function,
-      connect_op<Protocol, SocketService, Iterator,
-        ConnectCondition, ComposedConnectHandler>* this_handler)
+      iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
+        ConnectCondition, IteratorConnectHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 } // namespace detail
 
-template <typename Protocol, typename SocketService,
-    typename Iterator, typename ComposedConnectHandler>
-inline BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition,
+    typename RangeConnectHandler, typename Allocator>
+struct associated_allocator<
+    detail::range_connect_op<Protocol BOOST_ASIO_SVC_TARG,
+      EndpointSequence, ConnectCondition, RangeConnectHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<
+      RangeConnectHandler, Allocator>::type type;
+
+  static type get(
+      const detail::range_connect_op<Protocol BOOST_ASIO_SVC_TARG,
+        EndpointSequence, ConnectCondition, RangeConnectHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<RangeConnectHandler,
+        Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename ConnectCondition,
+    typename RangeConnectHandler, typename Executor>
+struct associated_executor<
+    detail::range_connect_op<Protocol BOOST_ASIO_SVC_TARG,
+      EndpointSequence, ConnectCondition, RangeConnectHandler>,
+    Executor>
+{
+  typedef typename associated_executor<
+      RangeConnectHandler, Executor>::type type;
+
+  static type get(
+      const detail::range_connect_op<Protocol BOOST_ASIO_SVC_TARG,
+        EndpointSequence, ConnectCondition, RangeConnectHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<RangeConnectHandler,
+        Executor>::get(h.handler_, ex);
+  }
+};
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Iterator, typename ConnectCondition,
+    typename IteratorConnectHandler, typename Allocator>
+struct associated_allocator<
+    detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
+      ConnectCondition, IteratorConnectHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<
+      IteratorConnectHandler, Allocator>::type type;
+
+  static type get(
+      const detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG,
+        Iterator, ConnectCondition, IteratorConnectHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<IteratorConnectHandler,
+        Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Iterator, typename ConnectCondition,
+    typename IteratorConnectHandler, typename Executor>
+struct associated_executor<
+    detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
+      ConnectCondition, IteratorConnectHandler>,
+    Executor>
+{
+  typedef typename associated_executor<
+      IteratorConnectHandler, Executor>::type type;
+
+  static type get(
+      const detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG,
+        Iterator, ConnectCondition, IteratorConnectHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<IteratorConnectHandler,
+        Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename EndpointSequence, typename RangeConnectHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(RangeConnectHandler,
+    void (boost::system::error_code, typename Protocol::endpoint))
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints,
+    BOOST_ASIO_MOVE_ARG(RangeConnectHandler) handler,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type*)
+{
+  // If you get an error on the following line it means that your handler does
+  // not meet the documented type requirements for a RangeConnectHandler.
+  BOOST_ASIO_RANGE_CONNECT_HANDLER_CHECK(
+      RangeConnectHandler, handler, typename Protocol::endpoint) type_check;
+
+  async_completion<RangeConnectHandler,
+    void (boost::system::error_code, typename Protocol::endpoint)>
+      init(handler);
+
+  detail::range_connect_op<Protocol BOOST_ASIO_SVC_TARG, EndpointSequence,
+    detail::default_connect_condition,
+      BOOST_ASIO_HANDLER_TYPE(RangeConnectHandler,
+        void (boost::system::error_code, typename Protocol::endpoint))>(s,
+          endpoints, detail::default_connect_condition(),
+            init.completion_handler)(boost::system::error_code(), 1);
+
+  return init.result.get();
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Iterator, typename IteratorConnectHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s,
-    Iterator begin, BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler)
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    Iterator begin, BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type*)
 {
   // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a ComposedConnectHandler.
-  BOOST_ASIO_COMPOSED_CONNECT_HANDLER_CHECK(
-      ComposedConnectHandler, handler, Iterator) type_check;
+  // not meet the documented type requirements for a IteratorConnectHandler.
+  BOOST_ASIO_ITERATOR_CONNECT_HANDLER_CHECK(
+      IteratorConnectHandler, handler, Iterator) type_check;
 
-  detail::async_result_init<ComposedConnectHandler,
-    void (boost::system::error_code, Iterator)> init(
-      BOOST_ASIO_MOVE_CAST(ComposedConnectHandler)(handler));
+  async_completion<IteratorConnectHandler,
+    void (boost::system::error_code, Iterator)> init(handler);
 
-  detail::connect_op<Protocol, SocketService, Iterator,
+  detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
     detail::default_connect_condition, BOOST_ASIO_HANDLER_TYPE(
-      ComposedConnectHandler, void (boost::system::error_code, Iterator))>(s,
-        begin, Iterator(), detail::default_connect_condition(), init.handler)(
-          boost::system::error_code(), 1);
+      IteratorConnectHandler, void (boost::system::error_code, Iterator))>(s,
+        begin, Iterator(), detail::default_connect_condition(),
+          init.completion_handler)(boost::system::error_code(), 1);
 
   return init.result.get();
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-template <typename Protocol, typename SocketService,
-    typename Iterator, typename ComposedConnectHandler>
-inline BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM,
+    typename Iterator, typename IteratorConnectHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s,
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end,
-    BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler)
+    BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler)
 {
   // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a ComposedConnectHandler.
-  BOOST_ASIO_COMPOSED_CONNECT_HANDLER_CHECK(
-      ComposedConnectHandler, handler, Iterator) type_check;
+  // not meet the documented type requirements for a IteratorConnectHandler.
+  BOOST_ASIO_ITERATOR_CONNECT_HANDLER_CHECK(
+      IteratorConnectHandler, handler, Iterator) type_check;
 
-  detail::async_result_init<ComposedConnectHandler,
-    void (boost::system::error_code, Iterator)> init(
-      BOOST_ASIO_MOVE_CAST(ComposedConnectHandler)(handler));
+  async_completion<IteratorConnectHandler,
+    void (boost::system::error_code, Iterator)> init(handler);
 
-  detail::connect_op<Protocol, SocketService, Iterator,
+  detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
     detail::default_connect_condition, BOOST_ASIO_HANDLER_TYPE(
-      ComposedConnectHandler, void (boost::system::error_code, Iterator))>(s,
-        begin, end, detail::default_connect_condition(), init.handler)(
+      IteratorConnectHandler, void (boost::system::error_code, Iterator))>(s,
+        begin, end, detail::default_connect_condition(),
+          init.completion_handler)(boost::system::error_code(), 1);
+
+  return init.result.get();
+}
+
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename EndpointSequence,
+    typename ConnectCondition, typename RangeConnectHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(RangeConnectHandler,
+    void (boost::system::error_code, typename Protocol::endpoint))
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
+    const EndpointSequence& endpoints, ConnectCondition connect_condition,
+    BOOST_ASIO_MOVE_ARG(RangeConnectHandler) handler,
+    typename enable_if<is_endpoint_sequence<
+        EndpointSequence>::value>::type*)
+{
+  // If you get an error on the following line it means that your handler does
+  // not meet the documented type requirements for a RangeConnectHandler.
+  BOOST_ASIO_RANGE_CONNECT_HANDLER_CHECK(
+      RangeConnectHandler, handler, typename Protocol::endpoint) type_check;
+
+  async_completion<RangeConnectHandler,
+    void (boost::system::error_code, typename Protocol::endpoint)>
+      init(handler);
+
+  detail::range_connect_op<Protocol BOOST_ASIO_SVC_TARG, EndpointSequence,
+    ConnectCondition, BOOST_ASIO_HANDLER_TYPE(RangeConnectHandler,
+      void (boost::system::error_code, typename Protocol::endpoint))>(s,
+        endpoints, connect_condition, init.completion_handler)(
           boost::system::error_code(), 1);
 
   return init.result.get();
 }
 
-template <typename Protocol, typename SocketService, typename Iterator,
-    typename ConnectCondition, typename ComposedConnectHandler>
-inline BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+    typename ConnectCondition, typename IteratorConnectHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s,
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, ConnectCondition connect_condition,
-    BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler)
+    BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler,
+    typename enable_if<!is_endpoint_sequence<Iterator>::value>::type*)
 {
   // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a ComposedConnectHandler.
-  BOOST_ASIO_COMPOSED_CONNECT_HANDLER_CHECK(
-      ComposedConnectHandler, handler, Iterator) type_check;
+  // not meet the documented type requirements for a IteratorConnectHandler.
+  BOOST_ASIO_ITERATOR_CONNECT_HANDLER_CHECK(
+      IteratorConnectHandler, handler, Iterator) type_check;
 
-  detail::async_result_init<ComposedConnectHandler,
-    void (boost::system::error_code, Iterator)> init(
-      BOOST_ASIO_MOVE_CAST(ComposedConnectHandler)(handler));
+  async_completion<IteratorConnectHandler,
+    void (boost::system::error_code, Iterator)> init(handler);
 
-  detail::connect_op<Protocol, SocketService, Iterator,
+  detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
     ConnectCondition, BOOST_ASIO_HANDLER_TYPE(
-      ComposedConnectHandler, void (boost::system::error_code, Iterator))>(s,
-        begin, Iterator(), connect_condition, init.handler)(
+      IteratorConnectHandler, void (boost::system::error_code, Iterator))>(s,
+        begin, Iterator(), connect_condition, init.completion_handler)(
           boost::system::error_code(), 1);
 
   return init.result.get();
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-template <typename Protocol, typename SocketService, typename Iterator,
-    typename ConnectCondition, typename ComposedConnectHandler>
-inline BOOST_ASIO_INITFN_RESULT_TYPE(ComposedConnectHandler,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM, typename Iterator,
+    typename ConnectCondition, typename IteratorConnectHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(IteratorConnectHandler,
     void (boost::system::error_code, Iterator))
-async_connect(basic_socket<Protocol, SocketService>& s,
+async_connect(basic_socket<Protocol BOOST_ASIO_SVC_TARG>& s,
     Iterator begin, Iterator end, ConnectCondition connect_condition,
-    BOOST_ASIO_MOVE_ARG(ComposedConnectHandler) handler)
+    BOOST_ASIO_MOVE_ARG(IteratorConnectHandler) handler)
 {
   // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a ComposedConnectHandler.
-  BOOST_ASIO_COMPOSED_CONNECT_HANDLER_CHECK(
-      ComposedConnectHandler, handler, Iterator) type_check;
+  // not meet the documented type requirements for a IteratorConnectHandler.
+  BOOST_ASIO_ITERATOR_CONNECT_HANDLER_CHECK(
+      IteratorConnectHandler, handler, Iterator) type_check;
 
-  detail::async_result_init<ComposedConnectHandler,
-    void (boost::system::error_code, Iterator)> init(
-      BOOST_ASIO_MOVE_CAST(ComposedConnectHandler)(handler));
+  async_completion<IteratorConnectHandler,
+    void (boost::system::error_code, Iterator)> init(handler);
 
-  detail::connect_op<Protocol, SocketService, Iterator,
+  detail::iterator_connect_op<Protocol BOOST_ASIO_SVC_TARG, Iterator,
     ConnectCondition, BOOST_ASIO_HANDLER_TYPE(
-      ComposedConnectHandler, void (boost::system::error_code, Iterator))>(s,
-        begin, end, connect_condition, init.handler)(
+      IteratorConnectHandler, void (boost::system::error_code, Iterator))>(s,
+        begin, end, connect_condition, init.completion_handler)(
           boost::system::error_code(), 1);
 
   return init.result.get();
diff --git a/include/boost/asio/impl/defer.hpp b/include/boost/asio/impl/defer.hpp
new file mode 100644
index 0000000000..afc29f965b
--- /dev/null
+++ b/include/boost/asio/impl/defer.hpp
@@ -0,0 +1,79 @@
+//
+// impl/defer.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_DEFER_HPP
+#define BOOST_ASIO_IMPL_DEFER_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/detail/work_dispatcher.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef BOOST_ASIO_HANDLER_TYPE(CompletionToken, void()) handler;
+
+  async_completion<CompletionToken, void()> init(token);
+
+  typename associated_executor<handler>::type ex(
+      (get_associated_executor)(init.completion_handler));
+
+  typename associated_allocator<handler>::type alloc(
+      (get_associated_allocator)(init.completion_handler));
+
+  ex.defer(BOOST_ASIO_MOVE_CAST(handler)(init.completion_handler), alloc);
+
+  return init.result.get();
+}
+
+template <typename Executor, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
+    const Executor& ex, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_executor<Executor>::value>::type*)
+{
+  typedef BOOST_ASIO_HANDLER_TYPE(CompletionToken, void()) handler;
+
+  async_completion<CompletionToken, void()> init(token);
+
+  typename associated_allocator<handler>::type alloc(
+      (get_associated_allocator)(init.completion_handler));
+
+  ex.defer(detail::work_dispatcher<handler>(init.completion_handler), alloc);
+
+  return init.result.get();
+}
+
+template <typename ExecutionContext, typename CompletionToken>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
+    ExecutionContext& ctx, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type*)
+{
+  return (defer)(ctx.get_executor(),
+      BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_DEFER_HPP
diff --git a/include/boost/asio/impl/dispatch.hpp b/include/boost/asio/impl/dispatch.hpp
new file mode 100644
index 0000000000..5589b375e3
--- /dev/null
+++ b/include/boost/asio/impl/dispatch.hpp
@@ -0,0 +1,80 @@
+//
+// impl/dispatch.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_DISPATCH_HPP
+#define BOOST_ASIO_IMPL_DISPATCH_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/detail/work_dispatcher.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) dispatch(
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef BOOST_ASIO_HANDLER_TYPE(CompletionToken, void()) handler;
+
+  async_completion<CompletionToken, void()> init(token);
+
+  typename associated_executor<handler>::type ex(
+      (get_associated_executor)(init.completion_handler));
+
+  typename associated_allocator<handler>::type alloc(
+      (get_associated_allocator)(init.completion_handler));
+
+  ex.dispatch(BOOST_ASIO_MOVE_CAST(handler)(init.completion_handler), alloc);
+
+  return init.result.get();
+}
+
+template <typename Executor, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) dispatch(
+    const Executor& ex, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_executor<Executor>::value>::type*)
+{
+  typedef BOOST_ASIO_HANDLER_TYPE(CompletionToken, void()) handler;
+
+  async_completion<CompletionToken, void()> init(token);
+
+  typename associated_allocator<handler>::type alloc(
+      (get_associated_allocator)(init.completion_handler));
+
+  ex.dispatch(detail::work_dispatcher<handler>(
+        init.completion_handler), alloc);
+
+  return init.result.get();
+}
+
+template <typename ExecutionContext, typename CompletionToken>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) dispatch(
+    ExecutionContext& ctx, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type*)
+{
+  return (dispatch)(ctx.get_executor(),
+      BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_DISPATCH_HPP
diff --git a/include/boost/asio/impl/execution_context.hpp b/include/boost/asio/impl/execution_context.hpp
new file mode 100644
index 0000000000..86acfc2d6e
--- /dev/null
+++ b/include/boost/asio/impl/execution_context.hpp
@@ -0,0 +1,109 @@
+//
+// impl/execution_context.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_EXECUTION_CONTEXT_HPP
+#define BOOST_ASIO_IMPL_EXECUTION_CONTEXT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/scoped_ptr.hpp>
+#include <boost/asio/detail/service_registry.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+template <typename Service>
+inline Service& use_service(execution_context& e)
+{
+  // Check that Service meets the necessary type requirements.
+  (void)static_cast<execution_context::service*>(static_cast<Service*>(0));
+
+  return e.service_registry_->template use_service<Service>();
+}
+
+#if !defined(GENERATING_DOCUMENTATION)
+# if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename Service, typename... Args>
+Service& make_service(execution_context& e, BOOST_ASIO_MOVE_ARG(Args)... args)
+{
+  detail::scoped_ptr<Service> svc(
+      new Service(e, BOOST_ASIO_MOVE_CAST(Args)(args)...));
+  e.service_registry_->template add_service<Service>(svc.get());
+  Service& result = *svc;
+  svc.release();
+  return result;
+}
+
+# else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename Service>
+Service& make_service(execution_context& e)
+{
+  detail::scoped_ptr<Service> svc(new Service(e));
+  e.service_registry_->template add_service<Service>(svc.get());
+  Service& result = *svc;
+  svc.release();
+  return result;
+}
+
+#define BOOST_ASIO_PRIVATE_MAKE_SERVICE_DEF(n) \
+  template <typename Service, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  Service& make_service(execution_context& e, \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    detail::scoped_ptr<Service> svc( \
+        new Service(e, BOOST_ASIO_VARIADIC_MOVE_ARGS(n))); \
+    e.service_registry_->template add_service<Service>(svc.get()); \
+    Service& result = *svc; \
+    svc.release(); \
+    return result; \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_MAKE_SERVICE_DEF)
+#undef BOOST_ASIO_PRIVATE_MAKE_SERVICE_DEF
+
+# endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename Service>
+inline void add_service(execution_context& e, Service* svc)
+{
+  // Check that Service meets the necessary type requirements.
+  (void)static_cast<execution_context::service*>(static_cast<Service*>(0));
+
+  e.service_registry_->template add_service<Service>(svc);
+}
+
+template <typename Service>
+inline bool has_service(execution_context& e)
+{
+  // Check that Service meets the necessary type requirements.
+  (void)static_cast<execution_context::service*>(static_cast<Service*>(0));
+
+  return e.service_registry_->template has_service<Service>();
+}
+
+inline execution_context& execution_context::service::context()
+{
+  return owner_;
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_EXECUTION_CONTEXT_HPP
diff --git a/include/boost/asio/impl/execution_context.ipp b/include/boost/asio/impl/execution_context.ipp
new file mode 100644
index 0000000000..01e92f6604
--- /dev/null
+++ b/include/boost/asio/impl/execution_context.ipp
@@ -0,0 +1,84 @@
+//
+// impl/execution_context.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_EXECUTION_CONTEXT_IPP
+#define BOOST_ASIO_IMPL_EXECUTION_CONTEXT_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/execution_context.hpp>
+#include <boost/asio/detail/service_registry.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+execution_context::execution_context()
+  : service_registry_(new boost::asio::detail::service_registry(*this))
+{
+}
+
+execution_context::~execution_context()
+{
+  shutdown();
+  destroy();
+  delete service_registry_;
+}
+
+void execution_context::shutdown()
+{
+  service_registry_->shutdown_services();
+}
+
+void execution_context::destroy()
+{
+  service_registry_->destroy_services();
+}
+
+void execution_context::notify_fork(
+    boost::asio::execution_context::fork_event event)
+{
+  service_registry_->notify_fork(event);
+}
+
+execution_context::service::service(execution_context& owner)
+  : owner_(owner),
+    next_(0)
+{
+}
+
+execution_context::service::~service()
+{
+}
+
+void execution_context::service::notify_fork(execution_context::fork_event)
+{
+}
+
+service_already_exists::service_already_exists()
+  : std::logic_error("Service already exists.")
+{
+}
+
+invalid_service_owner::invalid_service_owner()
+  : std::logic_error("Invalid service owner.")
+{
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_EXECUTION_CONTEXT_IPP
diff --git a/include/boost/asio/impl/executor.hpp b/include/boost/asio/impl/executor.hpp
new file mode 100644
index 0000000000..e97a7d57c9
--- /dev/null
+++ b/include/boost/asio/impl/executor.hpp
@@ -0,0 +1,388 @@
+//
+// impl/executor.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_EXECUTOR_HPP
+#define BOOST_ASIO_IMPL_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/atomic_count.hpp>
+#include <boost/asio/detail/executor_op.hpp>
+#include <boost/asio/detail/global.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/recycling_allocator.hpp>
+#include <boost/asio/executor.hpp>
+#include <boost/asio/system_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+#if !defined(GENERATING_DOCUMENTATION)
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+
+// Lightweight, move-only function object wrapper.
+class executor::function
+{
+public:
+  template <typename F, typename Alloc>
+  explicit function(F f, const Alloc& a)
+  {
+    // Allocate and construct an operation to wrap the function.
+    typedef detail::executor_op<F, Alloc> op;
+    typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+    op_ = new (p.v) op(BOOST_ASIO_MOVE_CAST(F)(f), a);
+    p.v = 0;
+  }
+
+  function(function&& other)
+    : op_(other.op_)
+  {
+    other.op_ = 0;
+  }
+
+  ~function()
+  {
+    if (op_)
+      op_->destroy();
+  }
+
+  void operator()()
+  {
+    if (op_)
+    {
+      detail::scheduler_operation* op = op_;
+      op_ = 0;
+      op->complete(this, boost::system::error_code(), 0);
+    }
+  }
+
+private:
+  detail::scheduler_operation* op_;
+};
+
+#else // defined(BOOST_ASIO_HAS_MOVE)
+
+// Not so lightweight, copyable function object wrapper.
+class executor::function
+{
+public:
+  template <typename F, typename Alloc>
+  explicit function(const F& f, const Alloc&)
+    : impl_(new impl<F>(f))
+  {
+  }
+
+  void operator()()
+  {
+    impl_->invoke_(impl_.get());
+  }
+
+private:
+  // Base class for polymorphic function implementations.
+  struct impl_base
+  {
+    void (*invoke_)(impl_base*);
+  };
+
+  // Polymorphic function implementation.
+  template <typename F>
+  struct impl : impl_base
+  {
+    impl(const F& f)
+      : function_(f)
+    {
+      invoke_ = &function::invoke<F>;
+    }
+
+    F function_;
+  };
+
+  // Helper to invoke a function.
+  template <typename F>
+  static void invoke(impl_base* i)
+  {
+    static_cast<impl<F>*>(i)->function_();
+  }
+
+  detail::shared_ptr<impl_base> impl_;
+};
+
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+// Default polymorphic allocator implementation.
+template <typename Executor, typename Allocator>
+class executor::impl
+  : public executor::impl_base
+{
+public:
+  typedef BOOST_ASIO_REBIND_ALLOC(Allocator, impl) allocator_type;
+
+  static impl_base* create(const Executor& e, Allocator a = Allocator())
+  {
+    raw_mem mem(a);
+    impl* p = new (mem.ptr_) impl(e, a);
+    mem.ptr_ = 0;
+    return p;
+  }
+
+  impl(const Executor& e, const Allocator& a) BOOST_ASIO_NOEXCEPT
+    : impl_base(false),
+      ref_count_(1),
+      executor_(e),
+      allocator_(a)
+  {
+  }
+
+  impl_base* clone() const BOOST_ASIO_NOEXCEPT
+  {
+    ++ref_count_;
+    return const_cast<impl_base*>(static_cast<const impl_base*>(this));
+  }
+
+  void destroy() BOOST_ASIO_NOEXCEPT
+  {
+    if (--ref_count_ == 0)
+    {
+      allocator_type alloc(allocator_);
+      impl* p = this;
+      p->~impl();
+      alloc.deallocate(p, 1);
+    }
+  }
+
+  void on_work_started() BOOST_ASIO_NOEXCEPT
+  {
+    executor_.on_work_started();
+  }
+
+  void on_work_finished() BOOST_ASIO_NOEXCEPT
+  {
+    executor_.on_work_finished();
+  }
+
+  execution_context& context() BOOST_ASIO_NOEXCEPT
+  {
+    return executor_.context();
+  }
+
+  void dispatch(BOOST_ASIO_MOVE_ARG(function) f)
+  {
+    executor_.dispatch(BOOST_ASIO_MOVE_CAST(function)(f), allocator_);
+  }
+
+  void post(BOOST_ASIO_MOVE_ARG(function) f)
+  {
+    executor_.post(BOOST_ASIO_MOVE_CAST(function)(f), allocator_);
+  }
+
+  void defer(BOOST_ASIO_MOVE_ARG(function) f)
+  {
+    executor_.defer(BOOST_ASIO_MOVE_CAST(function)(f), allocator_);
+  }
+
+  type_id_result_type target_type() const BOOST_ASIO_NOEXCEPT
+  {
+    return type_id<Executor>();
+  }
+
+  void* target() BOOST_ASIO_NOEXCEPT
+  {
+    return &executor_;
+  }
+
+  const void* target() const BOOST_ASIO_NOEXCEPT
+  {
+    return &executor_;
+  }
+
+  bool equals(const impl_base* e) const BOOST_ASIO_NOEXCEPT
+  {
+    if (this == e)
+      return true;
+    if (target_type() != e->target_type())
+      return false;
+    return executor_ == *static_cast<const Executor*>(e->target());
+  }
+
+private:
+  mutable detail::atomic_count ref_count_;
+  Executor executor_;
+  Allocator allocator_;
+
+  struct raw_mem
+  {
+    allocator_type allocator_;
+    impl* ptr_;
+
+    explicit raw_mem(const Allocator& a)
+      : allocator_(a),
+        ptr_(allocator_.allocate(1))
+    {
+    }
+
+    ~raw_mem()
+    {
+      if (ptr_)
+        allocator_.deallocate(ptr_, 1);
+    }
+
+  private:
+    // Disallow copying and assignment.
+    raw_mem(const raw_mem&);
+    raw_mem operator=(const raw_mem&);
+  };
+};
+
+// Polymorphic allocator specialisation for system_executor.
+template <typename Allocator>
+class executor::impl<system_executor, Allocator>
+  : public executor::impl_base
+{
+public:
+  static impl_base* create(const system_executor&,
+      const Allocator& = Allocator())
+  {
+    return &detail::global<impl<system_executor, std::allocator<void> > >();
+  }
+
+  impl()
+    : impl_base(true)
+  {
+  }
+
+  impl_base* clone() const BOOST_ASIO_NOEXCEPT
+  {
+    return const_cast<impl_base*>(static_cast<const impl_base*>(this));
+  }
+
+  void destroy() BOOST_ASIO_NOEXCEPT
+  {
+  }
+
+  void on_work_started() BOOST_ASIO_NOEXCEPT
+  {
+    executor_.on_work_started();
+  }
+
+  void on_work_finished() BOOST_ASIO_NOEXCEPT
+  {
+    executor_.on_work_finished();
+  }
+
+  execution_context& context() BOOST_ASIO_NOEXCEPT
+  {
+    return executor_.context();
+  }
+
+  void dispatch(BOOST_ASIO_MOVE_ARG(function) f)
+  {
+    executor_.dispatch(BOOST_ASIO_MOVE_CAST(function)(f), allocator_);
+  }
+
+  void post(BOOST_ASIO_MOVE_ARG(function) f)
+  {
+    executor_.post(BOOST_ASIO_MOVE_CAST(function)(f), allocator_);
+  }
+
+  void defer(BOOST_ASIO_MOVE_ARG(function) f)
+  {
+    executor_.defer(BOOST_ASIO_MOVE_CAST(function)(f), allocator_);
+  }
+
+  type_id_result_type target_type() const BOOST_ASIO_NOEXCEPT
+  {
+    return type_id<system_executor>();
+  }
+
+  void* target() BOOST_ASIO_NOEXCEPT
+  {
+    return &executor_;
+  }
+
+  const void* target() const BOOST_ASIO_NOEXCEPT
+  {
+    return &executor_;
+  }
+
+  bool equals(const impl_base* e) const BOOST_ASIO_NOEXCEPT
+  {
+    return this == e;
+  }
+
+private:
+  system_executor executor_;
+  Allocator allocator_;
+};
+
+template <typename Executor>
+executor::executor(Executor e)
+  : impl_(impl<Executor, std::allocator<void> >::create(e))
+{
+}
+
+template <typename Executor, typename Allocator>
+executor::executor(allocator_arg_t, const Allocator& a, Executor e)
+  : impl_(impl<Executor, Allocator>::create(e, a))
+{
+}
+
+template <typename Function, typename Allocator>
+void executor::dispatch(BOOST_ASIO_MOVE_ARG(Function) f,
+    const Allocator& a) const
+{
+  impl_base* i = get_impl();
+  if (i->fast_dispatch_)
+    system_executor().dispatch(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+  else
+    i->dispatch(function(BOOST_ASIO_MOVE_CAST(Function)(f), a));
+}
+
+template <typename Function, typename Allocator>
+void executor::post(BOOST_ASIO_MOVE_ARG(Function) f,
+    const Allocator& a) const
+{
+  get_impl()->post(function(BOOST_ASIO_MOVE_CAST(Function)(f), a));
+}
+
+template <typename Function, typename Allocator>
+void executor::defer(BOOST_ASIO_MOVE_ARG(Function) f,
+    const Allocator& a) const
+{
+  get_impl()->defer(function(BOOST_ASIO_MOVE_CAST(Function)(f), a));
+}
+
+template <typename Executor>
+Executor* executor::target() BOOST_ASIO_NOEXCEPT
+{
+  return impl_ && impl_->target_type() == type_id<Executor>()
+    ? static_cast<Executor*>(impl_->target()) : 0;
+}
+
+template <typename Executor>
+const Executor* executor::target() const BOOST_ASIO_NOEXCEPT
+{
+  return impl_ && impl_->target_type() == type_id<Executor>()
+    ? static_cast<Executor*>(impl_->target()) : 0;
+}
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_EXECUTOR_HPP
diff --git a/include/boost/asio/ssl/basic_context.hpp b/include/boost/asio/impl/executor.ipp
similarity index 54%
rename from include/boost/asio/ssl/basic_context.hpp
rename to include/boost/asio/impl/executor.ipp
index 734398bc29..dbedbc6cf0 100644
--- a/include/boost/asio/ssl/basic_context.hpp
+++ b/include/boost/asio/impl/executor.ipp
@@ -1,6 +1,6 @@
 //
-// ssl/basic_context.hpp
-// ~~~~~~~~~~~~~~~~~~~~~
+// impl/executor.ipp
+// ~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -8,35 +8,33 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef BOOST_ASIO_SSL_BASIC_CONTEXT_HPP
-#define BOOST_ASIO_SSL_BASIC_CONTEXT_HPP
+#ifndef BOOST_ASIO_IMPL_EXECUTOR_IPP
+#define BOOST_ASIO_IMPL_EXECUTOR_IPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/old/basic_context.hpp>
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/executor.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
-namespace ssl {
-
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
 
-using boost::asio::ssl::old::basic_context;
+bad_executor::bad_executor() BOOST_ASIO_NOEXCEPT
+{
+}
 
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
+const char* bad_executor::what() const BOOST_ASIO_NOEXCEPT_OR_NOTHROW
+{
+  return "bad executor";
+}
 
-} // namespace ssl
 } // namespace asio
 } // namespace boost
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#endif // BOOST_ASIO_SSL_BASIC_CONTEXT_HPP
+#endif // BOOST_ASIO_IMPL_EXECUTOR_IPP
diff --git a/include/boost/asio/impl/handler_alloc_hook.ipp b/include/boost/asio/impl/handler_alloc_hook.ipp
index ddc84c75cf..d3e82e8bc2 100644
--- a/include/boost/asio/impl/handler_alloc_hook.ipp
+++ b/include/boost/asio/impl/handler_alloc_hook.ipp
@@ -16,38 +16,20 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/call_stack.hpp>
+#include <boost/asio/detail/thread_context.hpp>
+#include <boost/asio/detail/thread_info_base.hpp>
 #include <boost/asio/handler_alloc_hook.hpp>
 
-#if !defined(BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING)
-# if defined(BOOST_ASIO_HAS_IOCP)
-#  include <boost/asio/detail/win_iocp_thread_info.hpp>
-# else // defined(BOOST_ASIO_HAS_IOCP)
-#  include <boost/asio/detail/task_io_service_thread_info.hpp>
-# endif // defined(BOOST_ASIO_HAS_IOCP)
-#endif // !defined(BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING)
-
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
-#if defined(BOOST_ASIO_HAS_IOCP)
-namespace detail { class win_iocp_io_service; }
-#endif // defined(BOOST_ASIO_HAS_IOCP)
-
 void* asio_handler_allocate(std::size_t size, ...)
 {
 #if !defined(BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING)
-# if defined(BOOST_ASIO_HAS_IOCP)
-  typedef detail::win_iocp_io_service io_service_impl;
-  typedef detail::win_iocp_thread_info thread_info;
-# else // defined(BOOST_ASIO_HAS_IOCP)
-  typedef detail::task_io_service io_service_impl;
-  typedef detail::task_io_service_thread_info thread_info;
-# endif // defined(BOOST_ASIO_HAS_IOCP)
-  typedef detail::call_stack<io_service_impl, thread_info> call_stack;
-  return thread_info::allocate(call_stack::top(), size);
+  return detail::thread_info_base::allocate(
+      detail::thread_context::thread_call_stack::top(), size);
 #else // !defined(BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING)
   return ::operator new(size);
 #endif // !defined(BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING)
@@ -56,15 +38,8 @@ void* asio_handler_allocate(std::size_t size, ...)
 void asio_handler_deallocate(void* pointer, std::size_t size, ...)
 {
 #if !defined(BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING)
-# if defined(BOOST_ASIO_HAS_IOCP)
-  typedef detail::win_iocp_io_service io_service_impl;
-  typedef detail::win_iocp_thread_info thread_info;
-# else // defined(BOOST_ASIO_HAS_IOCP)
-  typedef detail::task_io_service io_service_impl;
-  typedef detail::task_io_service_thread_info thread_info;
-# endif // defined(BOOST_ASIO_HAS_IOCP)
-  typedef detail::call_stack<io_service_impl, thread_info> call_stack;
-  thread_info::deallocate(call_stack::top(), pointer, size);
+  detail::thread_info_base::deallocate(
+      detail::thread_context::thread_call_stack::top(), pointer, size);
 #else // !defined(BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING)
   (void)size;
   ::operator delete(pointer);
diff --git a/include/boost/asio/impl/io_context.hpp b/include/boost/asio/impl/io_context.hpp
new file mode 100644
index 0000000000..93e719ed80
--- /dev/null
+++ b/include/boost/asio/impl/io_context.hpp
@@ -0,0 +1,345 @@
+//
+// impl/io_context.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_IO_CONTEXT_HPP
+#define BOOST_ASIO_IMPL_IO_CONTEXT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/completion_handler.hpp>
+#include <boost/asio/detail/executor_op.hpp>
+#include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/recycling_allocator.hpp>
+#include <boost/asio/detail/service_registry.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+template <typename Service>
+inline Service& use_service(io_context& ioc)
+{
+  // Check that Service meets the necessary type requirements.
+  (void)static_cast<execution_context::service*>(static_cast<Service*>(0));
+  (void)static_cast<const execution_context::id*>(&Service::id);
+
+  return ioc.service_registry_->template use_service<Service>(ioc);
+}
+
+template <>
+inline detail::io_context_impl& use_service<detail::io_context_impl>(
+    io_context& ioc)
+{
+  return ioc.impl_;
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#if defined(BOOST_ASIO_HAS_IOCP)
+# include <boost/asio/detail/win_iocp_io_context.hpp>
+#else
+# include <boost/asio/detail/scheduler.hpp>
+#endif
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+inline io_context::executor_type
+io_context::get_executor() BOOST_ASIO_NOEXCEPT
+{
+  return executor_type(*this);
+}
+
+#if defined(BOOST_ASIO_HAS_CHRONO)
+
+template <typename Rep, typename Period>
+std::size_t io_context::run_for(
+    const chrono::duration<Rep, Period>& rel_time)
+{
+  return this->run_until(chrono::steady_clock::now() + rel_time);
+}
+
+template <typename Clock, typename Duration>
+std::size_t io_context::run_until(
+    const chrono::time_point<Clock, Duration>& abs_time)
+{
+  std::size_t n = 0;
+  while (this->run_one_until(abs_time))
+    if (n != (std::numeric_limits<std::size_t>::max)())
+      ++n;
+  return n;
+}
+
+template <typename Rep, typename Period>
+std::size_t io_context::run_one_for(
+    const chrono::duration<Rep, Period>& rel_time)
+{
+  return this->run_one_until(chrono::steady_clock::now() + rel_time);
+}
+
+template <typename Clock, typename Duration>
+std::size_t io_context::run_one_until(
+    const chrono::time_point<Clock, Duration>& abs_time)
+{
+  typename Clock::time_point now = Clock::now();
+  while (now < abs_time)
+  {
+    typename Clock::duration rel_time = abs_time - now;
+    if (rel_time > chrono::seconds(1))
+      rel_time = chrono::seconds(1);
+
+    boost::system::error_code ec;
+    std::size_t s = impl_.wait_one(
+        static_cast<long>(chrono::duration_cast<
+          chrono::microseconds>(rel_time).count()), ec);
+    boost::asio::detail::throw_error(ec);
+
+    if (s || impl_.stopped())
+      return s;
+
+    now = Clock::now();
+  }
+
+  return 0;
+}
+
+#endif // defined(BOOST_ASIO_HAS_CHRONO)
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+inline void io_context::reset()
+{
+  restart();
+}
+
+template <typename CompletionHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
+io_context::dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
+{
+  // If you get an error on the following line it means that your handler does
+  // not meet the documented type requirements for a CompletionHandler.
+  BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
+
+  async_completion<CompletionHandler, void ()> init(handler);
+
+  if (impl_.can_dispatch())
+  {
+    detail::fenced_block b(detail::fenced_block::full);
+    boost_asio_handler_invoke_helpers::invoke(
+        init.completion_handler, init.completion_handler);
+  }
+  else
+  {
+    // Allocate and construct an operation to wrap the handler.
+    typedef detail::completion_handler<
+      typename handler_type<CompletionHandler, void ()>::type> op;
+    typename op::ptr p = { detail::addressof(init.completion_handler),
+      op::ptr::allocate(init.completion_handler), 0 };
+    p.p = new (p.v) op(init.completion_handler);
+
+    BOOST_ASIO_HANDLER_CREATION((*this, *p.p,
+          "io_context", this, 0, "dispatch"));
+
+    impl_.do_dispatch(p.p);
+    p.v = p.p = 0;
+  }
+
+  return init.result.get();
+}
+
+template <typename CompletionHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
+io_context::post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
+{
+  // If you get an error on the following line it means that your handler does
+  // not meet the documented type requirements for a CompletionHandler.
+  BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
+
+  async_completion<CompletionHandler, void ()> init(handler);
+
+  bool is_continuation =
+    boost_asio_handler_cont_helpers::is_continuation(init.completion_handler);
+
+  // Allocate and construct an operation to wrap the handler.
+  typedef detail::completion_handler<
+    typename handler_type<CompletionHandler, void ()>::type> op;
+  typename op::ptr p = { detail::addressof(init.completion_handler),
+      op::ptr::allocate(init.completion_handler), 0 };
+  p.p = new (p.v) op(init.completion_handler);
+
+  BOOST_ASIO_HANDLER_CREATION((*this, *p.p,
+        "io_context", this, 0, "post"));
+
+  impl_.post_immediate_completion(p.p, is_continuation);
+  p.v = p.p = 0;
+
+  return init.result.get();
+}
+
+template <typename Handler>
+#if defined(GENERATING_DOCUMENTATION)
+unspecified
+#else
+inline detail::wrapped_handler<io_context&, Handler>
+#endif
+io_context::wrap(Handler handler)
+{
+  return detail::wrapped_handler<io_context&, Handler>(*this, handler);
+}
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+inline io_context&
+io_context::executor_type::context() const BOOST_ASIO_NOEXCEPT
+{
+  return io_context_;
+}
+
+inline void
+io_context::executor_type::on_work_started() const BOOST_ASIO_NOEXCEPT
+{
+  io_context_.impl_.work_started();
+}
+
+inline void
+io_context::executor_type::on_work_finished() const BOOST_ASIO_NOEXCEPT
+{
+  io_context_.impl_.work_finished();
+}
+
+template <typename Function, typename Allocator>
+void io_context::executor_type::dispatch(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Invoke immediately if we are already inside the thread pool.
+  if (io_context_.impl_.can_dispatch())
+  {
+    // Make a local, non-const copy of the function.
+    function_type tmp(BOOST_ASIO_MOVE_CAST(Function)(f));
+
+    detail::fenced_block b(detail::fenced_block::full);
+    boost_asio_handler_invoke_helpers::invoke(tmp, tmp);
+    return;
+  }
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator, detail::operation> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((this->context(), *p.p,
+        "io_context", &this->context(), 0, "post"));
+
+  io_context_.impl_.post_immediate_completion(p.p, false);
+  p.v = p.p = 0;
+}
+
+template <typename Function, typename Allocator>
+void io_context::executor_type::post(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator, detail::operation> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((this->context(), *p.p,
+        "io_context", &this->context(), 0, "post"));
+
+  io_context_.impl_.post_immediate_completion(p.p, false);
+  p.v = p.p = 0;
+}
+
+template <typename Function, typename Allocator>
+void io_context::executor_type::defer(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator, detail::operation> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((this->context(), *p.p,
+        "io_context", &this->context(), 0, "defer"));
+
+  io_context_.impl_.post_immediate_completion(p.p, true);
+  p.v = p.p = 0;
+}
+
+inline bool
+io_context::executor_type::running_in_this_thread() const BOOST_ASIO_NOEXCEPT
+{
+  return io_context_.impl_.can_dispatch();
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+inline io_context::work::work(boost::asio::io_context& io_context)
+  : io_context_impl_(io_context.impl_)
+{
+  io_context_impl_.work_started();
+}
+
+inline io_context::work::work(const work& other)
+  : io_context_impl_(other.io_context_impl_)
+{
+  io_context_impl_.work_started();
+}
+
+inline io_context::work::~work()
+{
+  io_context_impl_.work_finished();
+}
+
+inline boost::asio::io_context& io_context::work::get_io_context()
+{
+  return static_cast<boost::asio::io_context&>(io_context_impl_.context());
+}
+
+inline boost::asio::io_context& io_context::work::get_io_service()
+{
+  return static_cast<boost::asio::io_context&>(io_context_impl_.context());
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+inline boost::asio::io_context& io_context::service::get_io_context()
+{
+  return static_cast<boost::asio::io_context&>(context());
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+inline boost::asio::io_context& io_context::service::get_io_service()
+{
+  return static_cast<boost::asio::io_context&>(context());
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_IO_CONTEXT_HPP
diff --git a/include/boost/asio/impl/io_context.ipp b/include/boost/asio/impl/io_context.ipp
new file mode 100644
index 0000000000..0dd24713c5
--- /dev/null
+++ b/include/boost/asio/impl/io_context.ipp
@@ -0,0 +1,176 @@
+//
+// impl/io_context.ipp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_IO_CONTEXT_IPP
+#define BOOST_ASIO_IMPL_IO_CONTEXT_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/detail/concurrency_hint.hpp>
+#include <boost/asio/detail/limits.hpp>
+#include <boost/asio/detail/scoped_ptr.hpp>
+#include <boost/asio/detail/service_registry.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+
+#if defined(BOOST_ASIO_HAS_IOCP)
+# include <boost/asio/detail/win_iocp_io_context.hpp>
+#else
+# include <boost/asio/detail/scheduler.hpp>
+#endif
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+io_context::io_context()
+  : impl_(add_impl(new impl_type(*this, BOOST_ASIO_CONCURRENCY_HINT_DEFAULT)))
+{
+}
+
+io_context::io_context(int concurrency_hint)
+  : impl_(add_impl(new impl_type(*this, concurrency_hint == 1
+          ? BOOST_ASIO_CONCURRENCY_HINT_1 : concurrency_hint)))
+{
+}
+
+io_context::impl_type& io_context::add_impl(io_context::impl_type* impl)
+{
+  boost::asio::detail::scoped_ptr<impl_type> scoped_impl(impl);
+  boost::asio::add_service<impl_type>(*this, scoped_impl.get());
+  return *scoped_impl.release();
+}
+
+io_context::~io_context()
+{
+}
+
+io_context::count_type io_context::run()
+{
+  boost::system::error_code ec;
+  count_type s = impl_.run(ec);
+  boost::asio::detail::throw_error(ec);
+  return s;
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+io_context::count_type io_context::run(boost::system::error_code& ec)
+{
+  return impl_.run(ec);
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+io_context::count_type io_context::run_one()
+{
+  boost::system::error_code ec;
+  count_type s = impl_.run_one(ec);
+  boost::asio::detail::throw_error(ec);
+  return s;
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+io_context::count_type io_context::run_one(boost::system::error_code& ec)
+{
+  return impl_.run_one(ec);
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+io_context::count_type io_context::poll()
+{
+  boost::system::error_code ec;
+  count_type s = impl_.poll(ec);
+  boost::asio::detail::throw_error(ec);
+  return s;
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+io_context::count_type io_context::poll(boost::system::error_code& ec)
+{
+  return impl_.poll(ec);
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+io_context::count_type io_context::poll_one()
+{
+  boost::system::error_code ec;
+  count_type s = impl_.poll_one(ec);
+  boost::asio::detail::throw_error(ec);
+  return s;
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+io_context::count_type io_context::poll_one(boost::system::error_code& ec)
+{
+  return impl_.poll_one(ec);
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+void io_context::stop()
+{
+  impl_.stop();
+}
+
+bool io_context::stopped() const
+{
+  return impl_.stopped();
+}
+
+void io_context::restart()
+{
+  impl_.restart();
+}
+
+io_context::service::service(boost::asio::io_context& owner)
+  : execution_context::service(owner)
+{
+}
+
+io_context::service::~service()
+{
+}
+
+void io_context::service::shutdown()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  shutdown_service();
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+void io_context::service::shutdown_service()
+{
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+void io_context::service::notify_fork(io_context::fork_event ev)
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  fork_service(ev);
+#else // !defined(BOOST_ASIO_NO_DEPRECATED)
+  (void)ev;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+void io_context::service::fork_service(io_context::fork_event)
+{
+}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_IO_CONTEXT_IPP
diff --git a/include/boost/asio/impl/io_service.hpp b/include/boost/asio/impl/io_service.hpp
deleted file mode 100644
index beee3f3978..0000000000
--- a/include/boost/asio/impl/io_service.hpp
+++ /dev/null
@@ -1,156 +0,0 @@
-//
-// impl/io_service.hpp
-// ~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_IMPL_IO_SERVICE_HPP
-#define BOOST_ASIO_IMPL_IO_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/handler_type_requirements.hpp>
-#include <boost/asio/detail/service_registry.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-
-template <typename Service>
-inline Service& use_service(io_service& ios)
-{
-  // Check that Service meets the necessary type requirements.
-  (void)static_cast<io_service::service*>(static_cast<Service*>(0));
-  (void)static_cast<const io_service::id*>(&Service::id);
-
-  return ios.service_registry_->template use_service<Service>();
-}
-
-template <>
-inline detail::io_service_impl& use_service<detail::io_service_impl>(
-    io_service& ios)
-{
-  return ios.impl_;
-}
-
-template <typename Service>
-inline void add_service(io_service& ios, Service* svc)
-{
-  // Check that Service meets the necessary type requirements.
-  (void)static_cast<io_service::service*>(static_cast<Service*>(0));
-  (void)static_cast<const io_service::id*>(&Service::id);
-
-  ios.service_registry_->template add_service<Service>(svc);
-}
-
-template <typename Service>
-inline bool has_service(io_service& ios)
-{
-  // Check that Service meets the necessary type requirements.
-  (void)static_cast<io_service::service*>(static_cast<Service*>(0));
-  (void)static_cast<const io_service::id*>(&Service::id);
-
-  return ios.service_registry_->template has_service<Service>();
-}
-
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#if defined(BOOST_ASIO_HAS_IOCP)
-# include <boost/asio/detail/win_iocp_io_service.hpp>
-#else
-# include <boost/asio/detail/task_io_service.hpp>
-#endif
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-
-template <typename CompletionHandler>
-inline BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
-io_service::dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
-{
-  // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a CompletionHandler.
-  BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
-
-  detail::async_result_init<
-    CompletionHandler, void ()> init(
-      BOOST_ASIO_MOVE_CAST(CompletionHandler)(handler));
-
-  impl_.dispatch(init.handler);
-
-  return init.result.get();
-}
-
-template <typename CompletionHandler>
-inline BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
-io_service::post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
-{
-  // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a CompletionHandler.
-  BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
-
-  detail::async_result_init<
-    CompletionHandler, void ()> init(
-      BOOST_ASIO_MOVE_CAST(CompletionHandler)(handler));
-
-  impl_.post(init.handler);
-
-  return init.result.get();
-}
-
-template <typename Handler>
-#if defined(GENERATING_DOCUMENTATION)
-unspecified
-#else
-inline detail::wrapped_handler<io_service&, Handler>
-#endif
-io_service::wrap(Handler handler)
-{
-  return detail::wrapped_handler<io_service&, Handler>(*this, handler);
-}
-
-inline io_service::work::work(boost::asio::io_service& io_service)
-  : io_service_impl_(io_service.impl_)
-{
-  io_service_impl_.work_started();
-}
-
-inline io_service::work::work(const work& other)
-  : io_service_impl_(other.io_service_impl_)
-{
-  io_service_impl_.work_started();
-}
-
-inline io_service::work::~work()
-{
-  io_service_impl_.work_finished();
-}
-
-inline boost::asio::io_service& io_service::work::get_io_service()
-{
-  return io_service_impl_.get_io_service();
-}
-
-inline boost::asio::io_service& io_service::service::get_io_service()
-{
-  return owner_;
-}
-
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_IMPL_IO_SERVICE_HPP
diff --git a/include/boost/asio/impl/io_service.ipp b/include/boost/asio/impl/io_service.ipp
deleted file mode 100644
index 428db3f879..0000000000
--- a/include/boost/asio/impl/io_service.ipp
+++ /dev/null
@@ -1,157 +0,0 @@
-//
-// impl/io_service.ipp
-// ~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_IMPL_IO_SERVICE_IPP
-#define BOOST_ASIO_IMPL_IO_SERVICE_IPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/detail/limits.hpp>
-#include <boost/asio/detail/scoped_ptr.hpp>
-#include <boost/asio/detail/service_registry.hpp>
-#include <boost/asio/detail/throw_error.hpp>
-
-#if defined(BOOST_ASIO_HAS_IOCP)
-# include <boost/asio/detail/win_iocp_io_service.hpp>
-#else
-# include <boost/asio/detail/task_io_service.hpp>
-#endif
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-
-io_service::io_service()
-  : service_registry_(new boost::asio::detail::service_registry(
-        *this, static_cast<impl_type*>(0),
-        (std::numeric_limits<std::size_t>::max)())),
-    impl_(service_registry_->first_service<impl_type>())
-{
-}
-
-io_service::io_service(std::size_t concurrency_hint)
-  : service_registry_(new boost::asio::detail::service_registry(
-        *this, static_cast<impl_type*>(0), concurrency_hint)),
-    impl_(service_registry_->first_service<impl_type>())
-{
-}
-
-io_service::~io_service()
-{
-  delete service_registry_;
-}
-
-std::size_t io_service::run()
-{
-  boost::system::error_code ec;
-  std::size_t s = impl_.run(ec);
-  boost::asio::detail::throw_error(ec);
-  return s;
-}
-
-std::size_t io_service::run(boost::system::error_code& ec)
-{
-  return impl_.run(ec);
-}
-
-std::size_t io_service::run_one()
-{
-  boost::system::error_code ec;
-  std::size_t s = impl_.run_one(ec);
-  boost::asio::detail::throw_error(ec);
-  return s;
-}
-
-std::size_t io_service::run_one(boost::system::error_code& ec)
-{
-  return impl_.run_one(ec);
-}
-
-std::size_t io_service::poll()
-{
-  boost::system::error_code ec;
-  std::size_t s = impl_.poll(ec);
-  boost::asio::detail::throw_error(ec);
-  return s;
-}
-
-std::size_t io_service::poll(boost::system::error_code& ec)
-{
-  return impl_.poll(ec);
-}
-
-std::size_t io_service::poll_one()
-{
-  boost::system::error_code ec;
-  std::size_t s = impl_.poll_one(ec);
-  boost::asio::detail::throw_error(ec);
-  return s;
-}
-
-std::size_t io_service::poll_one(boost::system::error_code& ec)
-{
-  return impl_.poll_one(ec);
-}
-
-void io_service::stop()
-{
-  impl_.stop();
-}
-
-bool io_service::stopped() const
-{
-  return impl_.stopped();
-}
-
-void io_service::reset()
-{
-  impl_.reset();
-}
-
-void io_service::notify_fork(boost::asio::io_service::fork_event event)
-{
-  service_registry_->notify_fork(event);
-}
-
-io_service::service::service(boost::asio::io_service& owner)
-  : owner_(owner),
-    next_(0)
-{
-}
-
-io_service::service::~service()
-{
-}
-
-void io_service::service::fork_service(boost::asio::io_service::fork_event)
-{
-}
-
-service_already_exists::service_already_exists()
-  : std::logic_error("Service already exists.")
-{
-}
-
-invalid_service_owner::invalid_service_owner()
-  : std::logic_error("Invalid service owner.")
-{
-}
-
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_IMPL_IO_SERVICE_IPP
diff --git a/include/boost/asio/impl/post.hpp b/include/boost/asio/impl/post.hpp
new file mode 100644
index 0000000000..520633d42b
--- /dev/null
+++ b/include/boost/asio/impl/post.hpp
@@ -0,0 +1,79 @@
+//
+// impl/post.hpp
+// ~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_POST_HPP
+#define BOOST_ASIO_IMPL_POST_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/detail/work_dispatcher.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) post(
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef BOOST_ASIO_HANDLER_TYPE(CompletionToken, void()) handler;
+
+  async_completion<CompletionToken, void()> init(token);
+
+  typename associated_executor<handler>::type ex(
+      (get_associated_executor)(init.completion_handler));
+
+  typename associated_allocator<handler>::type alloc(
+      (get_associated_allocator)(init.completion_handler));
+
+  ex.post(BOOST_ASIO_MOVE_CAST(handler)(init.completion_handler), alloc);
+
+  return init.result.get();
+}
+
+template <typename Executor, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) post(
+    const Executor& ex, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_executor<Executor>::value>::type*)
+{
+  typedef BOOST_ASIO_HANDLER_TYPE(CompletionToken, void()) handler;
+
+  async_completion<CompletionToken, void()> init(token);
+
+  typename associated_allocator<handler>::type alloc(
+      (get_associated_allocator)(init.completion_handler));
+
+  ex.post(detail::work_dispatcher<handler>(init.completion_handler), alloc);
+
+  return init.result.get();
+}
+
+template <typename ExecutionContext, typename CompletionToken>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) post(
+    ExecutionContext& ctx, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type*)
+{
+  return (post)(ctx.get_executor(),
+      BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_POST_HPP
diff --git a/include/boost/asio/impl/read.hpp b/include/boost/asio/impl/read.hpp
index 8648e47918..886565f2e8 100644
--- a/include/boost/asio/impl/read.hpp
+++ b/include/boost/asio/impl/read.hpp
@@ -16,6 +16,8 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <algorithm>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/completion_condition.hpp>
 #include <boost/asio/detail/array_fwd.hpp>
@@ -35,30 +37,46 @@
 namespace boost {
 namespace asio {
 
+namespace detail
+{
+  template <typename SyncReadStream, typename MutableBufferSequence,
+      typename MutableBufferIterator, typename CompletionCondition>
+  std::size_t read_buffer_sequence(SyncReadStream& s,
+      const MutableBufferSequence& buffers, const MutableBufferIterator&,
+      CompletionCondition completion_condition, boost::system::error_code& ec)
+  {
+    ec = boost::system::error_code();
+    boost::asio::detail::consuming_buffers<mutable_buffer,
+        MutableBufferSequence, MutableBufferIterator> tmp(buffers);
+    while (!tmp.empty())
+    {
+      if (std::size_t max_size = detail::adapt_completion_condition_result(
+            completion_condition(ec, tmp.total_consumed())))
+        tmp.consume(s.read_some(tmp.prepare(max_size), ec));
+      else
+        break;
+    }
+    return tmp.total_consumed();;
+  }
+} // namespace detail
+
 template <typename SyncReadStream, typename MutableBufferSequence,
     typename CompletionCondition>
 std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
-    CompletionCondition completion_condition, boost::system::error_code& ec)
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type*)
 {
-  ec = boost::system::error_code();
-  boost::asio::detail::consuming_buffers<
-    mutable_buffer, MutableBufferSequence> tmp(buffers);
-  std::size_t total_transferred = 0;
-  tmp.prepare(detail::adapt_completion_condition_result(
-        completion_condition(ec, total_transferred)));
-  while (tmp.begin() != tmp.end())
-  {
-    std::size_t bytes_transferred = s.read_some(tmp, ec);
-    tmp.consume(bytes_transferred);
-    total_transferred += bytes_transferred;
-    tmp.prepare(detail::adapt_completion_condition_result(
-          completion_condition(ec, total_transferred)));
-  }
-  return total_transferred;
+  return detail::read_buffer_sequence(s, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition, ec);
 }
 
 template <typename SyncReadStream, typename MutableBufferSequence>
-inline std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers)
+inline std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type*)
 {
   boost::system::error_code ec;
   std::size_t bytes_transferred = read(s, buffers, transfer_all(), ec);
@@ -68,7 +86,10 @@ inline std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers)
 
 template <typename SyncReadStream, typename MutableBufferSequence>
 inline std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
-    boost::system::error_code& ec)
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type*)
 {
   return read(s, buffers, transfer_all(), ec);
 }
@@ -76,7 +97,10 @@ inline std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
 template <typename SyncReadStream, typename MutableBufferSequence,
     typename CompletionCondition>
 inline std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
-    CompletionCondition completion_condition)
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type*)
 {
   boost::system::error_code ec;
   std::size_t bytes_transferred = read(s, buffers, completion_condition, ec);
@@ -84,19 +108,25 @@ inline std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
   return bytes_transferred;
 }
 
-#if !defined(BOOST_ASIO_NO_IOSTREAM)
-
-template <typename SyncReadStream, typename Allocator,
+template <typename SyncReadStream, typename DynamicBuffer,
     typename CompletionCondition>
 std::size_t read(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
-    CompletionCondition completion_condition, boost::system::error_code& ec)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
 {
+  typename decay<DynamicBuffer>::type b(
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers));
+
   ec = boost::system::error_code();
   std::size_t total_transferred = 0;
   std::size_t max_size = detail::adapt_completion_condition_result(
         completion_condition(ec, total_transferred));
-  std::size_t bytes_available = read_size_helper(b, max_size);
+  std::size_t bytes_available = std::min<std::size_t>(
+        std::max<std::size_t>(512, b.capacity() - b.size()),
+        std::min<std::size_t>(max_size, b.max_size() - b.size()));
   while (bytes_available > 0)
   {
     std::size_t bytes_transferred = s.read_some(b.prepare(bytes_available), ec);
@@ -104,27 +134,81 @@ std::size_t read(SyncReadStream& s,
     total_transferred += bytes_transferred;
     max_size = detail::adapt_completion_condition_result(
           completion_condition(ec, total_transferred));
-    bytes_available = read_size_helper(b, max_size);
+    bytes_available = std::min<std::size_t>(
+          std::max<std::size_t>(512, b.capacity() - b.size()),
+          std::min<std::size_t>(max_size, b.max_size() - b.size()));
   }
   return total_transferred;
 }
 
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 inline std::size_t read(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
 {
   boost::system::error_code ec;
-  std::size_t bytes_transferred = read(s, b, transfer_all(), ec);
+  std::size_t bytes_transferred = read(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers), transfer_all(), ec);
   boost::asio::detail::throw_error(ec, "read");
   return bytes_transferred;
 }
 
+template <typename SyncReadStream, typename DynamicBuffer>
+inline std::size_t read(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
+{
+  return read(s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      transfer_all(), ec);
+}
+
+template <typename SyncReadStream, typename DynamicBuffer,
+    typename CompletionCondition>
+inline std::size_t read(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
+{
+  boost::system::error_code ec;
+  std::size_t bytes_transferred = read(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      completion_condition, ec);
+  boost::asio::detail::throw_error(ec, "read");
+  return bytes_transferred;
+}
+
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+template <typename SyncReadStream, typename Allocator,
+    typename CompletionCondition>
+inline std::size_t read(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    CompletionCondition completion_condition, boost::system::error_code& ec)
+{
+  return read(s, basic_streambuf_ref<Allocator>(b), completion_condition, ec);
+}
+
+template <typename SyncReadStream, typename Allocator>
+inline std::size_t read(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b)
+{
+  return read(s, basic_streambuf_ref<Allocator>(b));
+}
+
 template <typename SyncReadStream, typename Allocator>
 inline std::size_t read(SyncReadStream& s,
     boost::asio::basic_streambuf<Allocator>& b,
     boost::system::error_code& ec)
 {
-  return read(s, b, transfer_all(), ec);
+  return read(s, basic_streambuf_ref<Allocator>(b), ec);
 }
 
 template <typename SyncReadStream, typename Allocator,
@@ -133,18 +217,17 @@ inline std::size_t read(SyncReadStream& s,
     boost::asio::basic_streambuf<Allocator>& b,
     CompletionCondition completion_condition)
 {
-  boost::system::error_code ec;
-  std::size_t bytes_transferred = read(s, b, completion_condition, ec);
-  boost::asio::detail::throw_error(ec, "read");
-  return bytes_transferred;
+  return read(s, basic_streambuf_ref<Allocator>(b), completion_condition);
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 namespace detail
 {
   template <typename AsyncReadStream, typename MutableBufferSequence,
-      typename CompletionCondition, typename ReadHandler>
+      typename MutableBufferIterator, typename CompletionCondition,
+      typename ReadHandler>
   class read_op
     : detail::base_from_completion_cond<CompletionCondition>
   {
@@ -156,7 +239,6 @@ namespace detail
         stream_(stream),
         buffers_(buffers),
         start_(0),
-        total_transferred_(0),
         handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
     {
     }
@@ -167,7 +249,6 @@ namespace detail
         stream_(other.stream_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(other.handler_)
     {
     }
@@ -177,7 +258,6 @@ namespace detail
         stream_(other.stream_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
     {
     }
@@ -186,285 +266,39 @@ namespace detail
     void operator()(const boost::system::error_code& ec,
         std::size_t bytes_transferred, int start = 0)
     {
+      std::size_t max_size;
       switch (start_ = start)
       {
         case 1:
-        buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-        for (;;)
+        max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        do
         {
-          stream_.async_read_some(buffers_,
+          stream_.async_read_some(buffers_.prepare(max_size),
               BOOST_ASIO_MOVE_CAST(read_op)(*this));
           return; default:
-          total_transferred_ += bytes_transferred;
           buffers_.consume(bytes_transferred);
-          buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-          if ((!ec && bytes_transferred == 0)
-              || buffers_.begin() == buffers_.end())
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncReadStream& stream_;
-    boost::asio::detail::consuming_buffers<
-      mutable_buffer, MutableBufferSequence> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    ReadHandler handler_;
-  };
-
-  template <typename AsyncReadStream,
-      typename CompletionCondition, typename ReadHandler>
-  class read_op<AsyncReadStream, boost::asio::mutable_buffers_1,
-      CompletionCondition, ReadHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    read_op(AsyncReadStream& stream,
-        const boost::asio::mutable_buffers_1& buffers,
-        CompletionCondition completion_condition, ReadHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        stream_(stream),
-        buffer_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    read_op(const read_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    read_op(read_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          stream_.async_read_some(
-              boost::asio::buffer(buffer_ + total_transferred_, n),
-              BOOST_ASIO_MOVE_CAST(read_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == boost::asio::buffer_size(buffer_))
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncReadStream& stream_;
-    boost::asio::mutable_buffer buffer_;
-    int start_;
-    std::size_t total_transferred_;
-    ReadHandler handler_;
-  };
-
-  template <typename AsyncReadStream, typename Elem,
-      typename CompletionCondition, typename ReadHandler>
-  class read_op<AsyncReadStream, boost::array<Elem, 2>,
-      CompletionCondition, ReadHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    read_op(AsyncReadStream& stream, const boost::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, ReadHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        stream_(stream),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    read_op(const read_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    read_op(read_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          boost::array<boost::asio::mutable_buffer, 2> >::type bufs = {{
-        boost::asio::mutable_buffer(buffers_[0]),
-        boost::asio::mutable_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          stream_.async_read_some(bufs, BOOST_ASIO_MOVE_CAST(read_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncReadStream& stream_;
-    boost::array<Elem, 2> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    ReadHandler handler_;
-  };
-
-#if defined(BOOST_ASIO_HAS_STD_ARRAY)
-
-  template <typename AsyncReadStream, typename Elem,
-      typename CompletionCondition, typename ReadHandler>
-  class read_op<AsyncReadStream, std::array<Elem, 2>,
-      CompletionCondition, ReadHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    read_op(AsyncReadStream& stream, const std::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, ReadHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        stream_(stream),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    read_op(const read_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    read_op(read_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          std::array<boost::asio::mutable_buffer, 2> >::type bufs = {{
-        boost::asio::mutable_buffer(buffers_[0]),
-        boost::asio::mutable_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          stream_.async_read_some(bufs, BOOST_ASIO_MOVE_CAST(read_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
+          if ((!ec && bytes_transferred == 0) || buffers_.empty())
             break;
-        }
+          max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        } while (max_size > 0);
 
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
+        handler_(ec, buffers_.total_consumed());
       }
     }
 
   //private:
     AsyncReadStream& stream_;
-    std::array<Elem, 2> buffers_;
+    boost::asio::detail::consuming_buffers<mutable_buffer,
+        MutableBufferSequence, MutableBufferIterator> buffers_;
     int start_;
-    std::size_t total_transferred_;
     ReadHandler handler_;
   };
 
-#endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
-
   template <typename AsyncReadStream, typename MutableBufferSequence,
-      typename CompletionCondition, typename ReadHandler>
+      typename MutableBufferIterator, typename CompletionCondition,
+      typename ReadHandler>
   inline void* asio_handler_allocate(std::size_t size,
-      read_op<AsyncReadStream, MutableBufferSequence,
+      read_op<AsyncReadStream, MutableBufferSequence, MutableBufferIterator,
         CompletionCondition, ReadHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
@@ -472,9 +306,10 @@ namespace detail
   }
 
   template <typename AsyncReadStream, typename MutableBufferSequence,
-      typename CompletionCondition, typename ReadHandler>
+      typename MutableBufferIterator, typename CompletionCondition,
+      typename ReadHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
-      read_op<AsyncReadStream, MutableBufferSequence,
+      read_op<AsyncReadStream, MutableBufferSequence, MutableBufferIterator,
         CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
@@ -482,9 +317,10 @@ namespace detail
   }
 
   template <typename AsyncReadStream, typename MutableBufferSequence,
-      typename CompletionCondition, typename ReadHandler>
+      typename MutableBufferIterator, typename CompletionCondition,
+      typename ReadHandler>
   inline bool asio_handler_is_continuation(
-      read_op<AsyncReadStream, MutableBufferSequence,
+      read_op<AsyncReadStream, MutableBufferSequence, MutableBufferIterator,
         CompletionCondition, ReadHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
@@ -493,10 +329,10 @@ namespace detail
   }
 
   template <typename Function, typename AsyncReadStream,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
   inline void asio_handler_invoke(Function& function,
-      read_op<AsyncReadStream, MutableBufferSequence,
+      read_op<AsyncReadStream, MutableBufferSequence, MutableBufferIterator,
         CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
@@ -504,38 +340,93 @@ namespace detail
   }
 
   template <typename Function, typename AsyncReadStream,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
   inline void asio_handler_invoke(const Function& function,
-      read_op<AsyncReadStream, MutableBufferSequence,
+      read_op<AsyncReadStream, MutableBufferSequence, MutableBufferIterator,
         CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
+
+  template <typename AsyncReadStream, typename MutableBufferSequence,
+      typename MutableBufferIterator, typename CompletionCondition,
+      typename ReadHandler>
+  inline void start_read_buffer_sequence_op(AsyncReadStream& stream,
+      const MutableBufferSequence& buffers, const MutableBufferIterator&,
+      CompletionCondition completion_condition, ReadHandler& handler)
+  {
+    detail::read_op<AsyncReadStream, MutableBufferSequence,
+      MutableBufferIterator, CompletionCondition, ReadHandler>(
+        stream, buffers, completion_condition, handler)(
+          boost::system::error_code(), 0, 1);
+  }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream, typename MutableBufferSequence,
+    typename MutableBufferIterator, typename CompletionCondition,
+    typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::read_op<AsyncReadStream, MutableBufferSequence,
+      MutableBufferIterator, CompletionCondition, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::read_op<AsyncReadStream, MutableBufferSequence,
+        MutableBufferIterator, CompletionCondition, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncReadStream, typename MutableBufferSequence,
+    typename MutableBufferIterator, typename CompletionCondition,
+    typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::read_op<AsyncReadStream, MutableBufferSequence,
+      MutableBufferIterator, CompletionCondition, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::read_op<AsyncReadStream, MutableBufferSequence,
+        MutableBufferIterator, CompletionCondition, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename AsyncReadStream, typename MutableBufferSequence,
     typename CompletionCondition, typename ReadHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
     CompletionCondition completion_condition,
-    BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type*)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::read_op<AsyncReadStream, MutableBufferSequence,
-    CompletionCondition, BOOST_ASIO_HANDLER_TYPE(
-      ReadHandler, void (boost::system::error_code, std::size_t))>(
-        s, buffers, completion_condition, init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_read_buffer_sequence_op(s, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition,
+      init.completion_handler);
 
   return init.result.get();
 }
@@ -545,42 +436,41 @@ template <typename AsyncReadStream, typename MutableBufferSequence,
 inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
-    BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type*)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::read_op<AsyncReadStream, MutableBufferSequence,
-    detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(
-      ReadHandler, void (boost::system::error_code, std::size_t))>(
-        s, buffers, transfer_all(), init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_read_buffer_sequence_op(s, buffers,
+      boost::asio::buffer_sequence_begin(buffers), transfer_all(),
+      init.completion_handler);
 
   return init.result.get();
 }
 
-#if !defined(BOOST_ASIO_NO_IOSTREAM)
-
 namespace detail
 {
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename CompletionCondition, typename ReadHandler>
-  class read_streambuf_op
+  class read_dynbuf_op
     : detail::base_from_completion_cond<CompletionCondition>
   {
   public:
-    read_streambuf_op(AsyncReadStream& stream,
-        basic_streambuf<Allocator>& streambuf,
+    template <typename BufferSequence>
+    read_dynbuf_op(AsyncReadStream& stream,
+        BOOST_ASIO_MOVE_ARG(BufferSequence) buffers,
         CompletionCondition completion_condition, ReadHandler& handler)
       : detail::base_from_completion_cond<
           CompletionCondition>(completion_condition),
         stream_(stream),
-        streambuf_(streambuf),
+        buffers_(BOOST_ASIO_MOVE_CAST(BufferSequence)(buffers)),
         start_(0),
         total_transferred_(0),
         handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
@@ -588,20 +478,20 @@ namespace detail
     }
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    read_streambuf_op(const read_streambuf_op& other)
+    read_dynbuf_op(const read_dynbuf_op& other)
       : detail::base_from_completion_cond<CompletionCondition>(other),
         stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(other.buffers_),
         start_(other.start_),
         total_transferred_(other.total_transferred_),
         handler_(other.handler_)
     {
     }
 
-    read_streambuf_op(read_streambuf_op&& other)
+    read_dynbuf_op(read_dynbuf_op&& other)
       : detail::base_from_completion_cond<CompletionCondition>(other),
         stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(BOOST_ASIO_MOVE_CAST(DynamicBuffer)(other.buffers_)),
         start_(other.start_),
         total_transferred_(other.total_transferred_),
         handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
@@ -617,16 +507,24 @@ namespace detail
       {
         case 1:
         max_size = this->check_for_completion(ec, total_transferred_);
-        bytes_available = read_size_helper(streambuf_, max_size);
+        bytes_available = std::min<std::size_t>(
+              std::max<std::size_t>(512,
+                buffers_.capacity() - buffers_.size()),
+              std::min<std::size_t>(max_size,
+                buffers_.max_size() - buffers_.size()));
         for (;;)
         {
-          stream_.async_read_some(streambuf_.prepare(bytes_available),
-              BOOST_ASIO_MOVE_CAST(read_streambuf_op)(*this));
+          stream_.async_read_some(buffers_.prepare(bytes_available),
+              BOOST_ASIO_MOVE_CAST(read_dynbuf_op)(*this));
           return; default:
           total_transferred_ += bytes_transferred;
-          streambuf_.commit(bytes_transferred);
+          buffers_.commit(bytes_transferred);
           max_size = this->check_for_completion(ec, total_transferred_);
-          bytes_available = read_size_helper(streambuf_, max_size);
+          bytes_available = std::min<std::size_t>(
+                std::max<std::size_t>(512,
+                  buffers_.capacity() - buffers_.size()),
+                std::min<std::size_t>(max_size,
+                  buffers_.max_size() - buffers_.size()));
           if ((!ec && bytes_transferred == 0) || bytes_available == 0)
             break;
         }
@@ -637,36 +535,36 @@ namespace detail
 
   //private:
     AsyncReadStream& stream_;
-    boost::asio::basic_streambuf<Allocator>& streambuf_;
+    DynamicBuffer buffers_;
     int start_;
     std::size_t total_transferred_;
     ReadHandler handler_;
   };
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename CompletionCondition, typename ReadHandler>
   inline void* asio_handler_allocate(std::size_t size,
-      read_streambuf_op<AsyncReadStream, Allocator,
+      read_dynbuf_op<AsyncReadStream, DynamicBuffer,
         CompletionCondition, ReadHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename CompletionCondition, typename ReadHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
-      read_streambuf_op<AsyncReadStream, Allocator,
+      read_dynbuf_op<AsyncReadStream, DynamicBuffer,
         CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename CompletionCondition, typename ReadHandler>
   inline bool asio_handler_is_continuation(
-      read_streambuf_op<AsyncReadStream, Allocator,
+      read_dynbuf_op<AsyncReadStream, DynamicBuffer,
         CompletionCondition, ReadHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
@@ -675,9 +573,10 @@ namespace detail
   }
 
   template <typename Function, typename AsyncReadStream,
-      typename Allocator, typename CompletionCondition, typename ReadHandler>
+      typename DynamicBuffer, typename CompletionCondition,
+      typename ReadHandler>
   inline void asio_handler_invoke(Function& function,
-      read_streambuf_op<AsyncReadStream, Allocator,
+      read_dynbuf_op<AsyncReadStream, DynamicBuffer,
         CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
@@ -685,9 +584,10 @@ namespace detail
   }
 
   template <typename Function, typename AsyncReadStream,
-      typename Allocator, typename CompletionCondition, typename ReadHandler>
+      typename DynamicBuffer, typename CompletionCondition,
+      typename ReadHandler>
   inline void asio_handler_invoke(const Function& function,
-      read_streambuf_op<AsyncReadStream, Allocator,
+      read_dynbuf_op<AsyncReadStream, DynamicBuffer,
         CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
@@ -695,57 +595,119 @@ namespace detail
   }
 } // namespace detail
 
-template <typename AsyncReadStream, typename Allocator,
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename CompletionCondition, typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::read_dynbuf_op<AsyncReadStream,
+      DynamicBuffer, CompletionCondition, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::read_dynbuf_op<AsyncReadStream,
+        DynamicBuffer, CompletionCondition, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename CompletionCondition, typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::read_dynbuf_op<AsyncReadStream,
+      DynamicBuffer, CompletionCondition, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::read_dynbuf_op<AsyncReadStream,
+        DynamicBuffer, CompletionCondition, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read(AsyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
+{
+  return async_read(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      transfer_all(), BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+}
+
+template <typename AsyncReadStream, typename DynamicBuffer,
     typename CompletionCondition, typename ReadHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read(AsyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
     CompletionCondition completion_condition,
-    BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::read_streambuf_op<AsyncReadStream, Allocator,
-    CompletionCondition, BOOST_ASIO_HANDLER_TYPE(
-      ReadHandler, void (boost::system::error_code, std::size_t))>(
-        s, b, completion_condition, init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::read_dynbuf_op<AsyncReadStream,
+    typename decay<DynamicBuffer>::type,
+      CompletionCondition, BOOST_ASIO_HANDLER_TYPE(
+        ReadHandler, void (boost::system::error_code, std::size_t))>(
+          s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+            completion_condition, init.completion_handler)(
+              boost::system::error_code(), 0, 1);
 
   return init.result.get();
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
 template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
-async_read(AsyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
+async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b,
     BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
 {
-  // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a ReadHandler.
-  BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
-
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
+  return async_read(s, basic_streambuf_ref<Allocator>(b),
       BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+}
 
-  detail::read_streambuf_op<AsyncReadStream, Allocator,
-    detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(
-      ReadHandler, void (boost::system::error_code, std::size_t))>(
-        s, b, transfer_all(), init.handler)(
-          boost::system::error_code(), 0, 1);
-
-  return init.result.get();
+template <typename AsyncReadStream, typename Allocator,
+    typename CompletionCondition, typename ReadHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b,
+    CompletionCondition completion_condition,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+{
+  return async_read(s, basic_streambuf_ref<Allocator>(b),
+      completion_condition, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/impl/read_at.hpp b/include/boost/asio/impl/read_at.hpp
index 0ec8a94e44..457bc056f4 100644
--- a/include/boost/asio/impl/read_at.hpp
+++ b/include/boost/asio/impl/read_at.hpp
@@ -16,6 +16,8 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <algorithm>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/completion_condition.hpp>
 #include <boost/asio/detail/array_fwd.hpp>
@@ -35,28 +37,41 @@
 namespace boost {
 namespace asio {
 
+namespace detail
+{
+  template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
+      typename MutableBufferIterator, typename CompletionCondition>
+  std::size_t read_at_buffer_sequence(SyncRandomAccessReadDevice& d,
+      uint64_t offset, const MutableBufferSequence& buffers,
+      const MutableBufferIterator&, CompletionCondition completion_condition,
+      boost::system::error_code& ec)
+  {
+    ec = boost::system::error_code();
+    boost::asio::detail::consuming_buffers<mutable_buffer,
+        MutableBufferSequence, MutableBufferIterator> tmp(buffers);
+    while (!tmp.empty())
+    {
+      if (std::size_t max_size = detail::adapt_completion_condition_result(
+            completion_condition(ec, tmp.total_consumed())))
+      {
+        tmp.consume(d.read_some_at(offset + tmp.total_consumed(),
+              tmp.prepare(max_size), ec));
+      }
+      else
+        break;
+    }
+    return tmp.total_consumed();;
+  }
+} // namespace detail
+
 template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence,
     typename CompletionCondition>
 std::size_t read_at(SyncRandomAccessReadDevice& d,
     uint64_t offset, const MutableBufferSequence& buffers,
     CompletionCondition completion_condition, boost::system::error_code& ec)
 {
-  ec = boost::system::error_code();
-  boost::asio::detail::consuming_buffers<
-    mutable_buffer, MutableBufferSequence> tmp(buffers);
-  std::size_t total_transferred = 0;
-  tmp.prepare(detail::adapt_completion_condition_result(
-        completion_condition(ec, total_transferred)));
-  while (tmp.begin() != tmp.end())
-  {
-    std::size_t bytes_transferred = d.read_some_at(
-        offset + total_transferred, tmp, ec);
-    tmp.consume(bytes_transferred);
-    total_transferred += bytes_transferred;
-    tmp.prepare(detail::adapt_completion_condition_result(
-          completion_condition(ec, total_transferred)));
-  }
-  return total_transferred;
+  return detail::read_at_buffer_sequence(d, offset, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition, ec);
 }
 
 template <typename SyncRandomAccessReadDevice, typename MutableBufferSequence>
@@ -91,6 +106,7 @@ inline std::size_t read_at(SyncRandomAccessReadDevice& d,
   return bytes_transferred;
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 template <typename SyncRandomAccessReadDevice, typename Allocator,
@@ -150,12 +166,13 @@ inline std::size_t read_at(SyncRandomAccessReadDevice& d,
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 namespace detail
 {
   template <typename AsyncRandomAccessReadDevice,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
   class read_at_op
     : detail::base_from_completion_cond<CompletionCondition>
   {
@@ -169,7 +186,6 @@ namespace detail
         offset_(offset),
         buffers_(buffers),
         start_(0),
-        total_transferred_(0),
         handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
     {
     }
@@ -181,7 +197,6 @@ namespace detail
         offset_(other.offset_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(other.handler_)
     {
     }
@@ -192,7 +207,6 @@ namespace detail
         offset_(other.offset_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
     {
     }
@@ -201,326 +215,64 @@ namespace detail
     void operator()(const boost::system::error_code& ec,
         std::size_t bytes_transferred, int start = 0)
     {
+      std::size_t max_size;
       switch (start_ = start)
       {
         case 1:
-        buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-        for (;;)
+        max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        do
         {
-          device_.async_read_some_at(offset_ + total_transferred_,
-              buffers_, BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
+          device_.async_read_some_at(
+              offset_ + buffers_.total_consumed(), buffers_.prepare(max_size),
+              BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
           return; default:
-          total_transferred_ += bytes_transferred;
           buffers_.consume(bytes_transferred);
-          buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-          if ((!ec && bytes_transferred == 0)
-              || buffers_.begin() == buffers_.end())
+          if ((!ec && bytes_transferred == 0) || buffers_.empty())
             break;
-        }
+          max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        } while (max_size > 0);
 
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
+        handler_(ec, buffers_.total_consumed());
       }
     }
 
   //private:
     AsyncRandomAccessReadDevice& device_;
     uint64_t offset_;
-    boost::asio::detail::consuming_buffers<
-      mutable_buffer, MutableBufferSequence> buffers_;
+    boost::asio::detail::consuming_buffers<mutable_buffer,
+        MutableBufferSequence, MutableBufferIterator> buffers_;
     int start_;
-    std::size_t total_transferred_;
     ReadHandler handler_;
   };
 
   template <typename AsyncRandomAccessReadDevice,
+      typename MutableBufferSequence, typename MutableBufferIterator,
       typename CompletionCondition, typename ReadHandler>
-  class read_at_op<AsyncRandomAccessReadDevice,
-      boost::asio::mutable_buffers_1, CompletionCondition, ReadHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    read_at_op(AsyncRandomAccessReadDevice& device,
-        uint64_t offset, const boost::asio::mutable_buffers_1& buffers,
-        CompletionCondition completion_condition, ReadHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        device_(device),
-        offset_(offset),
-        buffer_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    read_at_op(const read_at_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    read_at_op(read_at_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          device_.async_read_some_at(offset_ + total_transferred_,
-              boost::asio::buffer(buffer_ + total_transferred_, n),
-              BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == boost::asio::buffer_size(buffer_))
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncRandomAccessReadDevice& device_;
-    uint64_t offset_;
-    boost::asio::mutable_buffer buffer_;
-    int start_;
-    std::size_t total_transferred_;
-    ReadHandler handler_;
-  };
-
-  template <typename AsyncRandomAccessReadDevice, typename Elem,
-      typename CompletionCondition, typename ReadHandler>
-  class read_at_op<AsyncRandomAccessReadDevice, boost::array<Elem, 2>,
-      CompletionCondition, ReadHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    read_at_op(AsyncRandomAccessReadDevice& device,
-        uint64_t offset, const boost::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, ReadHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        device_(device),
-        offset_(offset),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    read_at_op(const read_at_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    read_at_op(read_at_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          boost::array<boost::asio::mutable_buffer, 2> >::type bufs = {{
-        boost::asio::mutable_buffer(buffers_[0]),
-        boost::asio::mutable_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          device_.async_read_some_at(offset_ + total_transferred_,
-              bufs, BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncRandomAccessReadDevice& device_;
-    uint64_t offset_;
-    boost::array<Elem, 2> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    ReadHandler handler_;
-  };
-
-#if defined(BOOST_ASIO_HAS_STD_ARRAY)
-
-  template <typename AsyncRandomAccessReadDevice, typename Elem,
-      typename CompletionCondition, typename ReadHandler>
-  class read_at_op<AsyncRandomAccessReadDevice, std::array<Elem, 2>,
-      CompletionCondition, ReadHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    read_at_op(AsyncRandomAccessReadDevice& device,
-        uint64_t offset, const std::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, ReadHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        device_(device),
-        offset_(offset),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    read_at_op(const read_at_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    read_at_op(read_at_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(ReadHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          std::array<boost::asio::mutable_buffer, 2> >::type bufs = {{
-        boost::asio::mutable_buffer(buffers_[0]),
-        boost::asio::mutable_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          device_.async_read_some_at(offset_ + total_transferred_,
-              bufs, BOOST_ASIO_MOVE_CAST(read_at_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncRandomAccessReadDevice& device_;
-    uint64_t offset_;
-    std::array<Elem, 2> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    ReadHandler handler_;
-  };
-
-#endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
-
-  template <typename AsyncRandomAccessReadDevice,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
   inline void* asio_handler_allocate(std::size_t size,
       read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
-        CompletionCondition, ReadHandler>* this_handler)
+        MutableBufferIterator, CompletionCondition, ReadHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
   template <typename AsyncRandomAccessReadDevice,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
       read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
-        CompletionCondition, ReadHandler>* this_handler)
+        MutableBufferIterator, CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
   template <typename AsyncRandomAccessReadDevice,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
   inline bool asio_handler_is_continuation(
       read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
-        CompletionCondition, ReadHandler>* this_handler)
+        MutableBufferIterator, CompletionCondition, ReadHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
       : boost_asio_handler_cont_helpers::is_continuation(
@@ -528,42 +280,86 @@ namespace detail
   }
 
   template <typename Function, typename AsyncRandomAccessReadDevice,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
   inline void asio_handler_invoke(Function& function,
       read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
-        CompletionCondition, ReadHandler>* this_handler)
+        MutableBufferIterator, CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
   template <typename Function, typename AsyncRandomAccessReadDevice,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
   inline void asio_handler_invoke(const Function& function,
       read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
-        CompletionCondition, ReadHandler>* this_handler)
+        MutableBufferIterator, CompletionCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
   template <typename AsyncRandomAccessReadDevice,
-      typename MutableBufferSequence, typename CompletionCondition,
-      typename ReadHandler>
-  inline read_at_op<AsyncRandomAccessReadDevice,
-      MutableBufferSequence, CompletionCondition, ReadHandler>
-  make_read_at_op(AsyncRandomAccessReadDevice& d,
+      typename MutableBufferSequence, typename MutableBufferIterator,
+      typename CompletionCondition, typename ReadHandler>
+  inline void start_read_at_buffer_sequence_op(AsyncRandomAccessReadDevice& d,
       uint64_t offset, const MutableBufferSequence& buffers,
-      CompletionCondition completion_condition, ReadHandler handler)
+      const MutableBufferIterator&, CompletionCondition completion_condition,
+      ReadHandler& handler)
   {
-    return read_at_op<AsyncRandomAccessReadDevice,
-      MutableBufferSequence, CompletionCondition, ReadHandler>(
-        d, offset, buffers, completion_condition, handler);
+    detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
+      MutableBufferIterator, CompletionCondition, ReadHandler>(
+        d, offset, buffers, completion_condition, handler)(
+          boost::system::error_code(), 0, 1);
   }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncRandomAccessReadDevice,
+    typename MutableBufferSequence, typename MutableBufferIterator,
+    typename CompletionCondition, typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
+    MutableBufferIterator, CompletionCondition, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::read_at_op<AsyncRandomAccessReadDevice,
+      MutableBufferSequence, MutableBufferIterator,
+      CompletionCondition, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncRandomAccessReadDevice,
+    typename MutableBufferSequence, typename MutableBufferIterator,
+    typename CompletionCondition, typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
+    MutableBufferIterator, CompletionCondition, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::read_at_op<AsyncRandomAccessReadDevice,
+      MutableBufferSequence, MutableBufferIterator,
+      CompletionCondition, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename AsyncRandomAccessReadDevice, typename MutableBufferSequence,
     typename CompletionCondition, typename ReadHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
@@ -577,15 +373,12 @@ async_read_at(AsyncRandomAccessReadDevice& d,
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
-    CompletionCondition, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
-      void (boost::system::error_code, std::size_t))>(
-        d, offset, buffers, completion_condition, init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_read_at_buffer_sequence_op(d, offset, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition,
+      init.completion_handler);
 
   return init.result.get();
 }
@@ -602,19 +395,17 @@ async_read_at(AsyncRandomAccessReadDevice& d,
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::read_at_op<AsyncRandomAccessReadDevice, MutableBufferSequence,
-    detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
-      void (boost::system::error_code, std::size_t))>(
-        d, offset, buffers, transfer_all(), init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_read_at_buffer_sequence_op(d, offset, buffers,
+      boost::asio::buffer_sequence_begin(buffers), transfer_all(),
+      init.completion_handler);
 
   return init.result.get();
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 namespace detail
@@ -751,6 +542,46 @@ namespace detail
   }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncRandomAccessReadDevice, typename Allocator,
+    typename CompletionCondition, typename ReadHandler, typename Allocator1>
+struct associated_allocator<
+    detail::read_at_streambuf_op<AsyncRandomAccessReadDevice,
+      Allocator, CompletionCondition, ReadHandler>,
+    Allocator1>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator1>::type type;
+
+  static type get(
+      const detail::read_at_streambuf_op<AsyncRandomAccessReadDevice,
+        Allocator, CompletionCondition, ReadHandler>& h,
+      const Allocator1& a = Allocator1()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator1>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncRandomAccessReadDevice, typename Executor,
+    typename CompletionCondition, typename ReadHandler, typename Executor1>
+struct associated_executor<
+    detail::read_at_streambuf_op<AsyncRandomAccessReadDevice,
+      Executor, CompletionCondition, ReadHandler>,
+    Executor1>
+{
+  typedef typename associated_executor<ReadHandler, Executor1>::type type;
+
+  static type get(
+      const detail::read_at_streambuf_op<AsyncRandomAccessReadDevice,
+        Executor, CompletionCondition, ReadHandler>& h,
+      const Executor1& ex = Executor1()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor1>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename AsyncRandomAccessReadDevice, typename Allocator,
     typename CompletionCondition, typename ReadHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
@@ -764,14 +595,13 @@ async_read_at(AsyncRandomAccessReadDevice& d,
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   detail::read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
     CompletionCondition, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
       void (boost::system::error_code, std::size_t))>(
-        d, offset, b, completion_condition, init.handler)(
+        d, offset, b, completion_condition, init.completion_handler)(
           boost::system::error_code(), 0, 1);
 
   return init.result.get();
@@ -789,20 +619,20 @@ async_read_at(AsyncRandomAccessReadDevice& d,
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   detail::read_at_streambuf_op<AsyncRandomAccessReadDevice, Allocator,
     detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
       void (boost::system::error_code, std::size_t))>(
-        d, offset, b, transfer_all(), init.handler)(
+        d, offset, b, transfer_all(), init.completion_handler)(
           boost::system::error_code(), 0, 1);
 
   return init.result.get();
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/impl/read_until.hpp b/include/boost/asio/impl/read_until.hpp
index 737dedcdf2..c8a409f46b 100644
--- a/include/boost/asio/impl/read_until.hpp
+++ b/include/boost/asio/impl/read_until.hpp
@@ -19,6 +19,8 @@
 #include <string>
 #include <vector>
 #include <utility>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/buffers_iterator.hpp>
 #include <boost/asio/detail/bind_handler.hpp>
@@ -34,32 +36,35 @@
 namespace boost {
 namespace asio {
 
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 inline std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, char delim)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers, char delim)
 {
   boost::system::error_code ec;
-  std::size_t bytes_transferred = read_until(s, b, delim, ec);
+  std::size_t bytes_transferred = read_until(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers), delim, ec);
   boost::asio::detail::throw_error(ec, "read_until");
   return bytes_transferred;
 }
 
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, char delim,
-    boost::system::error_code& ec)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    char delim, boost::system::error_code& ec)
 {
+  typename decay<DynamicBuffer>::type b(
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers));
+
   std::size_t search_position = 0;
   for (;;)
   {
     // Determine the range of the data to be searched.
-    typedef typename boost::asio::basic_streambuf<
-      Allocator>::const_buffers_type const_buffers_type;
-    typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-    const_buffers_type buffers = b.data();
-    iterator begin = iterator::begin(buffers);
+    typedef typename DynamicBuffer::const_buffers_type buffers_type;
+    typedef buffers_iterator<buffers_type> iterator;
+    buffers_type data_buffers = b.data();
+    iterator begin = iterator::begin(data_buffers);
     iterator start_pos = begin + search_position;
-    iterator end = iterator::end(buffers);
+    iterator end = iterator::end(data_buffers);
 
     // Look for a match.
     iterator iter = std::find(start_pos, end, delim);
@@ -83,19 +88,23 @@ std::size_t read_until(SyncReadStream& s,
     }
 
     // Need more data.
-    std::size_t bytes_to_read = read_size_helper(b, 65536);
+    std::size_t bytes_to_read = std::min<std::size_t>(
+          std::max<std::size_t>(512, b.capacity() - b.size()),
+          std::min<std::size_t>(65536, b.max_size() - b.size()));
     b.commit(s.read_some(b.prepare(bytes_to_read), ec));
     if (ec)
       return 0;
   }
 }
 
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 inline std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const std::string& delim)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_STRING_VIEW_PARAM delim)
 {
   boost::system::error_code ec;
-  std::size_t bytes_transferred = read_until(s, b, delim, ec);
+  std::size_t bytes_transferred = read_until(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers), delim, ec);
   boost::asio::detail::throw_error(ec, "read_until");
   return bytes_transferred;
 }
@@ -135,22 +144,24 @@ namespace detail
   }
 } // namespace detail
 
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const std::string& delim,
-    boost::system::error_code& ec)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_STRING_VIEW_PARAM delim, boost::system::error_code& ec)
 {
+  typename decay<DynamicBuffer>::type b(
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers));
+
   std::size_t search_position = 0;
   for (;;)
   {
     // Determine the range of the data to be searched.
-    typedef typename boost::asio::basic_streambuf<
-      Allocator>::const_buffers_type const_buffers_type;
-    typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-    const_buffers_type buffers = b.data();
-    iterator begin = iterator::begin(buffers);
+    typedef typename DynamicBuffer::const_buffers_type buffers_type;
+    typedef buffers_iterator<buffers_type> iterator;
+    buffers_type data_buffers = b.data();
+    iterator begin = iterator::begin(data_buffers);
     iterator start_pos = begin + search_position;
-    iterator end = iterator::end(buffers);
+    iterator end = iterator::end(data_buffers);
 
     // Look for a match.
     std::pair<iterator, bool> result = detail::partial_search(
@@ -183,41 +194,48 @@ std::size_t read_until(SyncReadStream& s,
     }
 
     // Need more data.
-    std::size_t bytes_to_read = read_size_helper(b, 65536);
+    std::size_t bytes_to_read = std::min<std::size_t>(
+          std::max<std::size_t>(512, b.capacity() - b.size()),
+          std::min<std::size_t>(65536, b.max_size() - b.size()));
     b.commit(s.read_some(b.prepare(bytes_to_read), ec));
     if (ec)
       return 0;
   }
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if defined(BOOST_ASIO_HAS_BOOST_REGEX)
 
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 inline std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    const boost::regex& expr)
 {
   boost::system::error_code ec;
-  std::size_t bytes_transferred = read_until(s, b, expr, ec);
+  std::size_t bytes_transferred = read_until(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers), expr, ec);
   boost::asio::detail::throw_error(ec, "read_until");
   return bytes_transferred;
 }
 
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr,
-    boost::system::error_code& ec)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    const boost::regex& expr, boost::system::error_code& ec)
 {
+  typename decay<DynamicBuffer>::type b(
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers));
+
   std::size_t search_position = 0;
   for (;;)
   {
     // Determine the range of the data to be searched.
-    typedef typename boost::asio::basic_streambuf<
-      Allocator>::const_buffers_type const_buffers_type;
-    typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-    const_buffers_type buffers = b.data();
-    iterator begin = iterator::begin(buffers);
+    typedef typename DynamicBuffer::const_buffers_type buffers_type;
+    typedef buffers_iterator<buffers_type> iterator;
+    buffers_type data_buffers = b.data();
+    iterator begin = iterator::begin(data_buffers);
     iterator start_pos = begin + search_position;
-    iterator end = iterator::end(buffers);
+    iterator end = iterator::end(data_buffers);
 
     // Look for a match.
     boost::match_results<iterator,
@@ -261,23 +279,41 @@ std::size_t read_until(SyncReadStream& s,
 
 #endif // defined(BOOST_ASIO_HAS_BOOST_REGEX)
 
-template <typename SyncReadStream, typename Allocator, typename MatchCondition>
+template <typename SyncReadStream,
+    typename DynamicBuffer, typename MatchCondition>
+inline std::size_t read_until(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    MatchCondition match_condition,
+    typename enable_if<is_match_condition<MatchCondition>::value>::type*)
+{
+  boost::system::error_code ec;
+  std::size_t bytes_transferred = read_until(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      match_condition, ec);
+  boost::asio::detail::throw_error(ec, "read_until");
+  return bytes_transferred;
+}
+
+template <typename SyncReadStream,
+    typename DynamicBuffer, typename MatchCondition>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
     MatchCondition match_condition, boost::system::error_code& ec,
     typename enable_if<is_match_condition<MatchCondition>::value>::type*)
 {
+  typename decay<DynamicBuffer>::type b(
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers));
+
   std::size_t search_position = 0;
   for (;;)
   {
     // Determine the range of the data to be searched.
-    typedef typename boost::asio::basic_streambuf<
-      Allocator>::const_buffers_type const_buffers_type;
-    typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-    const_buffers_type buffers = b.data();
-    iterator begin = iterator::begin(buffers);
+    typedef typename DynamicBuffer::const_buffers_type buffers_type;
+    typedef buffers_iterator<buffers_type> iterator;
+    buffers_type data_buffers = b.data();
+    iterator begin = iterator::begin(data_buffers);
     iterator start_pos = begin + search_position;
-    iterator end = iterator::end(buffers);
+    iterator end = iterator::end(data_buffers);
 
     // Look for a match.
     std::pair<iterator, bool> result = match_condition(start_pos, end);
@@ -306,35 +342,100 @@ std::size_t read_until(SyncReadStream& s,
     }
 
     // Need more data.
-    std::size_t bytes_to_read = read_size_helper(b, 65536);
+    std::size_t bytes_to_read = std::min<std::size_t>(
+          std::max<std::size_t>(512, b.capacity() - b.size()),
+          std::min<std::size_t>(65536, b.max_size() - b.size()));
     b.commit(s.read_some(b.prepare(bytes_to_read), ec));
     if (ec)
       return 0;
   }
 }
 
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+template <typename SyncReadStream, typename Allocator>
+inline std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, char delim)
+{
+  return read_until(s, basic_streambuf_ref<Allocator>(b), delim);
+}
+
+template <typename SyncReadStream, typename Allocator>
+inline std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, char delim,
+    boost::system::error_code& ec)
+{
+  return read_until(s, basic_streambuf_ref<Allocator>(b), delim, ec);
+}
+
+template <typename SyncReadStream, typename Allocator>
+inline std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_STRING_VIEW_PARAM delim)
+{
+  return read_until(s, basic_streambuf_ref<Allocator>(b), delim);
+}
+
+template <typename SyncReadStream, typename Allocator>
+inline std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_STRING_VIEW_PARAM delim, boost::system::error_code& ec)
+{
+  return read_until(s, basic_streambuf_ref<Allocator>(b), delim, ec);
+}
+
+#if defined(BOOST_ASIO_HAS_BOOST_REGEX)
+
+template <typename SyncReadStream, typename Allocator>
+inline std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr)
+{
+  return read_until(s, basic_streambuf_ref<Allocator>(b), expr);
+}
+
+template <typename SyncReadStream, typename Allocator>
+inline std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr,
+    boost::system::error_code& ec)
+{
+  return read_until(s, basic_streambuf_ref<Allocator>(b), expr, ec);
+}
+
+#endif // defined(BOOST_ASIO_HAS_BOOST_REGEX)
+
 template <typename SyncReadStream, typename Allocator, typename MatchCondition>
 inline std::size_t read_until(SyncReadStream& s,
     boost::asio::basic_streambuf<Allocator>& b, MatchCondition match_condition,
     typename enable_if<is_match_condition<MatchCondition>::value>::type*)
 {
-  boost::system::error_code ec;
-  std::size_t bytes_transferred = read_until(s, b, match_condition, ec);
-  boost::asio::detail::throw_error(ec, "read_until");
-  return bytes_transferred;
+  return read_until(s, basic_streambuf_ref<Allocator>(b), match_condition);
+}
+
+template <typename SyncReadStream, typename Allocator, typename MatchCondition>
+inline std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    MatchCondition match_condition, boost::system::error_code& ec,
+    typename enable_if<is_match_condition<MatchCondition>::value>::type*)
+{
+  return read_until(s, basic_streambuf_ref<Allocator>(b), match_condition, ec);
 }
 
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 namespace detail
 {
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   class read_until_delim_op
   {
   public:
+    template <typename BufferSequence>
     read_until_delim_op(AsyncReadStream& stream,
-        boost::asio::basic_streambuf<Allocator>& streambuf,
+        BOOST_ASIO_MOVE_ARG(BufferSequence) buffers,
         char delim, ReadHandler& handler)
       : stream_(stream),
-        streambuf_(streambuf),
+        buffers_(BOOST_ASIO_MOVE_CAST(BufferSequence)(buffers)),
         delim_(delim),
         start_(0),
         search_position_(0),
@@ -345,7 +446,7 @@ namespace detail
 #if defined(BOOST_ASIO_HAS_MOVE)
     read_until_delim_op(const read_until_delim_op& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(other.buffers_),
         delim_(other.delim_),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -355,7 +456,7 @@ namespace detail
 
     read_until_delim_op(read_until_delim_op&& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(BOOST_ASIO_MOVE_CAST(DynamicBuffer)(other.buffers_)),
         delim_(other.delim_),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -376,13 +477,13 @@ namespace detail
         {
           {
             // Determine the range of the data to be searched.
-            typedef typename boost::asio::basic_streambuf<
-              Allocator>::const_buffers_type const_buffers_type;
-            typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-            const_buffers_type buffers = streambuf_.data();
-            iterator begin = iterator::begin(buffers);
+            typedef typename DynamicBuffer::const_buffers_type
+              buffers_type;
+            typedef buffers_iterator<buffers_type> iterator;
+            buffers_type data_buffers = buffers_.data();
+            iterator begin = iterator::begin(data_buffers);
             iterator start_pos = begin + search_position_;
-            iterator end = iterator::end(buffers);
+            iterator end = iterator::end(data_buffers);
 
             // Look for a match.
             iterator iter = std::find(start_pos, end, delim_);
@@ -394,7 +495,7 @@ namespace detail
             }
 
             // No match yet. Check if buffer is full.
-            else if (streambuf_.size() == streambuf_.max_size())
+            else if (buffers_.size() == buffers_.max_size())
             {
               search_position_ = not_found;
               bytes_to_read = 0;
@@ -405,7 +506,11 @@ namespace detail
             {
               // Next search can start with the new data.
               search_position_ = end - begin;
-              bytes_to_read = read_size_helper(streambuf_, 65536);
+              bytes_to_read = std::min<std::size_t>(
+                    std::max<std::size_t>(512,
+                      buffers_.capacity() - buffers_.size()),
+                    std::min<std::size_t>(65536,
+                      buffers_.max_size() - buffers_.size()));
             }
           }
 
@@ -414,10 +519,10 @@ namespace detail
             break;
 
           // Start a new asynchronous read operation to obtain more data.
-          stream_.async_read_some(streambuf_.prepare(bytes_to_read),
+          stream_.async_read_some(buffers_.prepare(bytes_to_read),
               BOOST_ASIO_MOVE_CAST(read_until_delim_op)(*this));
           return; default:
-          streambuf_.commit(bytes_transferred);
+          buffers_.commit(bytes_transferred);
           if (ec || bytes_transferred == 0)
             break;
         }
@@ -436,97 +541,143 @@ namespace detail
 
   //private:
     AsyncReadStream& stream_;
-    boost::asio::basic_streambuf<Allocator>& streambuf_;
+    DynamicBuffer buffers_;
     char delim_;
     int start_;
     std::size_t search_position_;
     ReadHandler handler_;
   };
 
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline void* asio_handler_allocate(std::size_t size,
       read_until_delim_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
       read_until_delim_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline bool asio_handler_is_continuation(
       read_until_delim_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
       : boost_asio_handler_cont_helpers::is_continuation(
           this_handler->handler_);
   }
 
-  template <typename Function, typename AsyncReadStream, typename Allocator,
-      typename ReadHandler>
+  template <typename Function, typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline void asio_handler_invoke(Function& function,
       read_until_delim_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
-  template <typename Function, typename AsyncReadStream, typename Allocator,
-      typename ReadHandler>
+  template <typename Function, typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline void asio_handler_invoke(const Function& function,
       read_until_delim_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 } // namespace detail
 
-template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::read_until_delim_op<AsyncReadStream,
+      DynamicBuffer, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::read_until_delim_op<AsyncReadStream,
+        DynamicBuffer, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::read_until_delim_op<AsyncReadStream,
+      DynamicBuffer, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::read_until_delim_op<AsyncReadStream,
+        DynamicBuffer, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read_until(AsyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, char delim,
-    BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    char delim, BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   detail::read_until_delim_op<AsyncReadStream,
-    Allocator, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
-      void (boost::system::error_code, std::size_t))>(
-        s, b, delim, init.handler)(
-          boost::system::error_code(), 0, 1);
+    typename decay<DynamicBuffer>::type,
+      BOOST_ASIO_HANDLER_TYPE(ReadHandler,
+        void (boost::system::error_code, std::size_t))>(
+          s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+            delim, init.completion_handler)(boost::system::error_code(), 0, 1);
 
   return init.result.get();
 }
 
 namespace detail
 {
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   class read_until_delim_string_op
   {
   public:
+    template <typename BufferSequence>
     read_until_delim_string_op(AsyncReadStream& stream,
-        boost::asio::basic_streambuf<Allocator>& streambuf,
+        BOOST_ASIO_MOVE_ARG(BufferSequence) buffers,
         const std::string& delim, ReadHandler& handler)
       : stream_(stream),
-        streambuf_(streambuf),
+        buffers_(BOOST_ASIO_MOVE_CAST(BufferSequence)(buffers)),
         delim_(delim),
         start_(0),
         search_position_(0),
@@ -537,7 +688,7 @@ namespace detail
 #if defined(BOOST_ASIO_HAS_MOVE)
     read_until_delim_string_op(const read_until_delim_string_op& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(other.buffers_),
         delim_(other.delim_),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -547,7 +698,7 @@ namespace detail
 
     read_until_delim_string_op(read_until_delim_string_op&& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(BOOST_ASIO_MOVE_CAST(DynamicBuffer)(other.buffers_)),
         delim_(BOOST_ASIO_MOVE_CAST(std::string)(other.delim_)),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -568,13 +719,13 @@ namespace detail
         {
           {
             // Determine the range of the data to be searched.
-            typedef typename boost::asio::basic_streambuf<
-              Allocator>::const_buffers_type const_buffers_type;
-            typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-            const_buffers_type buffers = streambuf_.data();
-            iterator begin = iterator::begin(buffers);
+            typedef typename DynamicBuffer::const_buffers_type
+              buffers_type;
+            typedef buffers_iterator<buffers_type> iterator;
+            buffers_type data_buffers = buffers_.data();
+            iterator begin = iterator::begin(data_buffers);
             iterator start_pos = begin + search_position_;
-            iterator end = iterator::end(buffers);
+            iterator end = iterator::end(data_buffers);
 
             // Look for a match.
             std::pair<iterator, bool> result = detail::partial_search(
@@ -587,7 +738,7 @@ namespace detail
             }
 
             // No match yet. Check if buffer is full.
-            else if (streambuf_.size() == streambuf_.max_size())
+            else if (buffers_.size() == buffers_.max_size())
             {
               search_position_ = not_found;
               bytes_to_read = 0;
@@ -608,7 +759,11 @@ namespace detail
                 search_position_ = end - begin;
               }
 
-              bytes_to_read = read_size_helper(streambuf_, 65536);
+              bytes_to_read = std::min<std::size_t>(
+                    std::max<std::size_t>(512,
+                      buffers_.capacity() - buffers_.size()),
+                    std::min<std::size_t>(65536,
+                      buffers_.max_size() - buffers_.size()));
             }
           }
 
@@ -617,10 +772,10 @@ namespace detail
             break;
 
           // Start a new asynchronous read operation to obtain more data.
-          stream_.async_read_some(streambuf_.prepare(bytes_to_read),
+          stream_.async_read_some(buffers_.prepare(bytes_to_read),
               BOOST_ASIO_MOVE_CAST(read_until_delim_string_op)(*this));
           return; default:
-          streambuf_.commit(bytes_transferred);
+          buffers_.commit(bytes_transferred);
           if (ec || bytes_transferred == 0)
             break;
         }
@@ -639,35 +794,38 @@ namespace detail
 
   //private:
     AsyncReadStream& stream_;
-    boost::asio::basic_streambuf<Allocator>& streambuf_;
+    DynamicBuffer buffers_;
     std::string delim_;
     int start_;
     std::size_t search_position_;
     ReadHandler handler_;
   };
 
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline void* asio_handler_allocate(std::size_t size,
       read_until_delim_string_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
       read_until_delim_string_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+  template <typename AsyncReadStream,
+      typename DynamicBuffer, typename ReadHandler>
   inline bool asio_handler_is_continuation(
       read_until_delim_string_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
       : boost_asio_handler_cont_helpers::is_continuation(
@@ -675,64 +833,109 @@ namespace detail
   }
 
   template <typename Function, typename AsyncReadStream,
-      typename Allocator, typename ReadHandler>
+      typename DynamicBuffer, typename ReadHandler>
   inline void asio_handler_invoke(Function& function,
       read_until_delim_string_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
   template <typename Function, typename AsyncReadStream,
-      typename Allocator, typename ReadHandler>
+      typename DynamicBuffer, typename ReadHandler>
   inline void asio_handler_invoke(const Function& function,
       read_until_delim_string_op<AsyncReadStream,
-        Allocator, ReadHandler>* this_handler)
+        DynamicBuffer, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 } // namespace detail
 
-template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::read_until_delim_string_op<AsyncReadStream,
+      DynamicBuffer, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::read_until_delim_string_op<AsyncReadStream,
+        DynamicBuffer, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::read_until_delim_string_op<AsyncReadStream,
+      DynamicBuffer, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::read_until_delim_string_op<AsyncReadStream,
+        DynamicBuffer, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read_until(AsyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const std::string& delim,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_STRING_VIEW_PARAM delim,
     BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   detail::read_until_delim_string_op<AsyncReadStream,
-    Allocator, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
-      void (boost::system::error_code, std::size_t))>(
-        s, b, delim, init.handler)(
-          boost::system::error_code(), 0, 1);
+    typename decay<DynamicBuffer>::type,
+      BOOST_ASIO_HANDLER_TYPE(ReadHandler,
+        void (boost::system::error_code, std::size_t))>(
+          s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+            static_cast<std::string>(delim),
+              init.completion_handler)(boost::system::error_code(), 0, 1);
 
   return init.result.get();
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if defined(BOOST_ASIO_HAS_BOOST_REGEX)
 
 namespace detail
 {
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename RegEx, typename ReadHandler>
   class read_until_expr_op
   {
   public:
+    template <typename BufferSequence>
     read_until_expr_op(AsyncReadStream& stream,
-        boost::asio::basic_streambuf<Allocator>& streambuf,
+        BOOST_ASIO_MOVE_ARG(BufferSequence) buffers,
         const boost::regex& expr, ReadHandler& handler)
       : stream_(stream),
-        streambuf_(streambuf),
+        buffers_(BOOST_ASIO_MOVE_CAST(BufferSequence)(buffers)),
         expr_(expr),
         start_(0),
         search_position_(0),
@@ -743,7 +946,7 @@ namespace detail
 #if defined(BOOST_ASIO_HAS_MOVE)
     read_until_expr_op(const read_until_expr_op& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(other.buffers_),
         expr_(other.expr_),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -753,7 +956,7 @@ namespace detail
 
     read_until_expr_op(read_until_expr_op&& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(BOOST_ASIO_MOVE_CAST(DynamicBuffer)(other.buffers_)),
         expr_(other.expr_),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -774,13 +977,13 @@ namespace detail
         {
           {
             // Determine the range of the data to be searched.
-            typedef typename boost::asio::basic_streambuf<
-              Allocator>::const_buffers_type const_buffers_type;
-            typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-            const_buffers_type buffers = streambuf_.data();
-            iterator begin = iterator::begin(buffers);
+            typedef typename DynamicBuffer::const_buffers_type
+              buffers_type;
+            typedef buffers_iterator<buffers_type> iterator;
+            buffers_type data_buffers = buffers_.data();
+            iterator begin = iterator::begin(data_buffers);
             iterator start_pos = begin + search_position_;
-            iterator end = iterator::end(buffers);
+            iterator end = iterator::end(data_buffers);
 
             // Look for a match.
             boost::match_results<iterator,
@@ -796,7 +999,7 @@ namespace detail
             }
 
             // No match yet. Check if buffer is full.
-            else if (streambuf_.size() == streambuf_.max_size())
+            else if (buffers_.size() == buffers_.max_size())
             {
               search_position_ = not_found;
               bytes_to_read = 0;
@@ -817,7 +1020,11 @@ namespace detail
                 search_position_ = end - begin;
               }
 
-              bytes_to_read = read_size_helper(streambuf_, 65536);
+              bytes_to_read = std::min<std::size_t>(
+                    std::max<std::size_t>(512,
+                      buffers_.capacity() - buffers_.size()),
+                    std::min<std::size_t>(65536,
+                      buffers_.max_size() - buffers_.size()));
             }
           }
 
@@ -826,10 +1033,10 @@ namespace detail
             break;
 
           // Start a new asynchronous read operation to obtain more data.
-          stream_.async_read_some(streambuf_.prepare(bytes_to_read),
+          stream_.async_read_some(buffers_.prepare(bytes_to_read),
               BOOST_ASIO_MOVE_CAST(read_until_expr_op)(*this));
           return; default:
-          streambuf_.commit(bytes_transferred);
+          buffers_.commit(bytes_transferred);
           if (ec || bytes_transferred == 0)
             break;
         }
@@ -848,85 +1055,127 @@ namespace detail
 
   //private:
     AsyncReadStream& stream_;
-    boost::asio::basic_streambuf<Allocator>& streambuf_;
+    DynamicBuffer buffers_;
     RegEx expr_;
     int start_;
     std::size_t search_position_;
     ReadHandler handler_;
   };
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename RegEx, typename ReadHandler>
   inline void* asio_handler_allocate(std::size_t size,
       read_until_expr_op<AsyncReadStream,
-        Allocator, RegEx, ReadHandler>* this_handler)
+        DynamicBuffer, RegEx, ReadHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename RegEx, typename ReadHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
       read_until_expr_op<AsyncReadStream,
-        Allocator, RegEx, ReadHandler>* this_handler)
+        DynamicBuffer, RegEx, ReadHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename RegEx, typename ReadHandler>
   inline bool asio_handler_is_continuation(
       read_until_expr_op<AsyncReadStream,
-        Allocator, RegEx, ReadHandler>* this_handler)
+        DynamicBuffer, RegEx, ReadHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
       : boost_asio_handler_cont_helpers::is_continuation(
           this_handler->handler_);
   }
 
-  template <typename Function, typename AsyncReadStream, typename Allocator,
-      typename RegEx, typename ReadHandler>
+  template <typename Function, typename AsyncReadStream,
+      typename DynamicBuffer, typename RegEx, typename ReadHandler>
   inline void asio_handler_invoke(Function& function,
       read_until_expr_op<AsyncReadStream,
-        Allocator, RegEx, ReadHandler>* this_handler)
+        DynamicBuffer, RegEx, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
-  template <typename Function, typename AsyncReadStream, typename Allocator,
-      typename RegEx, typename ReadHandler>
+  template <typename Function, typename AsyncReadStream,
+      typename DynamicBuffer, typename RegEx, typename ReadHandler>
   inline void asio_handler_invoke(const Function& function,
       read_until_expr_op<AsyncReadStream,
-        Allocator, RegEx, ReadHandler>* this_handler)
+        DynamicBuffer, RegEx, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 } // namespace detail
 
-template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename RegEx, typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::read_until_expr_op<AsyncReadStream,
+      DynamicBuffer, RegEx, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::read_until_expr_op<AsyncReadStream,
+        DynamicBuffer, RegEx, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename RegEx, typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::read_until_expr_op<AsyncReadStream,
+      DynamicBuffer, RegEx, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::read_until_expr_op<AsyncReadStream,
+        DynamicBuffer, RegEx, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read_until(AsyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    const boost::regex& expr,
     BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::read_until_expr_op<AsyncReadStream, Allocator,
-    boost::regex, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
-      void (boost::system::error_code, std::size_t))>(
-        s, b, expr, init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::read_until_expr_op<AsyncReadStream,
+    typename decay<DynamicBuffer>::type,
+      boost::regex, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
+        void (boost::system::error_code, std::size_t))>(
+          s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+            expr, init.completion_handler)(boost::system::error_code(), 0, 1);
 
   return init.result.get();
 }
@@ -935,16 +1184,17 @@ async_read_until(AsyncReadStream& s,
 
 namespace detail
 {
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename MatchCondition, typename ReadHandler>
   class read_until_match_op
   {
   public:
+    template <typename BufferSequence>
     read_until_match_op(AsyncReadStream& stream,
-        boost::asio::basic_streambuf<Allocator>& streambuf,
+        BOOST_ASIO_MOVE_ARG(BufferSequence) buffers,
         MatchCondition match_condition, ReadHandler& handler)
       : stream_(stream),
-        streambuf_(streambuf),
+        buffers_(BOOST_ASIO_MOVE_CAST(BufferSequence)(buffers)),
         match_condition_(match_condition),
         start_(0),
         search_position_(0),
@@ -955,7 +1205,7 @@ namespace detail
 #if defined(BOOST_ASIO_HAS_MOVE)
     read_until_match_op(const read_until_match_op& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(other.buffers_),
         match_condition_(other.match_condition_),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -965,7 +1215,7 @@ namespace detail
 
     read_until_match_op(read_until_match_op&& other)
       : stream_(other.stream_),
-        streambuf_(other.streambuf_),
+        buffers_(BOOST_ASIO_MOVE_CAST(DynamicBuffer)(other.buffers_)),
         match_condition_(other.match_condition_),
         start_(other.start_),
         search_position_(other.search_position_),
@@ -986,13 +1236,13 @@ namespace detail
         {
           {
             // Determine the range of the data to be searched.
-            typedef typename boost::asio::basic_streambuf<
-              Allocator>::const_buffers_type const_buffers_type;
-            typedef boost::asio::buffers_iterator<const_buffers_type> iterator;
-            const_buffers_type buffers = streambuf_.data();
-            iterator begin = iterator::begin(buffers);
+            typedef typename DynamicBuffer::const_buffers_type
+              buffers_type;
+            typedef buffers_iterator<buffers_type> iterator;
+            buffers_type data_buffers = buffers_.data();
+            iterator begin = iterator::begin(data_buffers);
             iterator start_pos = begin + search_position_;
-            iterator end = iterator::end(buffers);
+            iterator end = iterator::end(data_buffers);
 
             // Look for a match.
             std::pair<iterator, bool> result = match_condition_(start_pos, end);
@@ -1004,7 +1254,7 @@ namespace detail
             }
 
             // No match yet. Check if buffer is full.
-            else if (streambuf_.size() == streambuf_.max_size())
+            else if (buffers_.size() == buffers_.max_size())
             {
               search_position_ = not_found;
               bytes_to_read = 0;
@@ -1025,7 +1275,11 @@ namespace detail
                 search_position_ = end - begin;
               }
 
-              bytes_to_read = read_size_helper(streambuf_, 65536);
+              bytes_to_read = std::min<std::size_t>(
+                    std::max<std::size_t>(512,
+                      buffers_.capacity() - buffers_.size()),
+                    std::min<std::size_t>(65536,
+                      buffers_.max_size() - buffers_.size()));
             }
           }
 
@@ -1034,10 +1288,10 @@ namespace detail
             break;
 
           // Start a new asynchronous read operation to obtain more data.
-          stream_.async_read_some(streambuf_.prepare(bytes_to_read),
+          stream_.async_read_some(buffers_.prepare(bytes_to_read),
               BOOST_ASIO_MOVE_CAST(read_until_match_op)(*this));
           return; default:
-          streambuf_.commit(bytes_transferred);
+          buffers_.commit(bytes_transferred);
           if (ec || bytes_transferred == 0)
             break;
         }
@@ -1056,71 +1310,113 @@ namespace detail
 
   //private:
     AsyncReadStream& stream_;
-    boost::asio::basic_streambuf<Allocator>& streambuf_;
+    DynamicBuffer buffers_;
     MatchCondition match_condition_;
     int start_;
     std::size_t search_position_;
     ReadHandler handler_;
   };
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename MatchCondition, typename ReadHandler>
   inline void* asio_handler_allocate(std::size_t size,
-      read_until_match_op<AsyncReadStream,
-        Allocator, MatchCondition, ReadHandler>* this_handler)
+      read_until_match_op<AsyncReadStream, DynamicBuffer,
+        MatchCondition, ReadHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename MatchCondition, typename ReadHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
-      read_until_match_op<AsyncReadStream,
-        Allocator, MatchCondition, ReadHandler>* this_handler)
+      read_until_match_op<AsyncReadStream, DynamicBuffer,
+        MatchCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename AsyncReadStream, typename Allocator,
+  template <typename AsyncReadStream, typename DynamicBuffer,
       typename MatchCondition, typename ReadHandler>
   inline bool asio_handler_is_continuation(
-      read_until_match_op<AsyncReadStream,
-        Allocator, MatchCondition, ReadHandler>* this_handler)
+      read_until_match_op<AsyncReadStream, DynamicBuffer,
+        MatchCondition, ReadHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
       : boost_asio_handler_cont_helpers::is_continuation(
           this_handler->handler_);
   }
 
-  template <typename Function, typename AsyncReadStream, typename Allocator,
-      typename MatchCondition, typename ReadHandler>
+  template <typename Function, typename AsyncReadStream,
+      typename DynamicBuffer, typename MatchCondition,
+      typename ReadHandler>
   inline void asio_handler_invoke(Function& function,
-      read_until_match_op<AsyncReadStream,
-        Allocator, MatchCondition, ReadHandler>* this_handler)
+      read_until_match_op<AsyncReadStream, DynamicBuffer,
+        MatchCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
-  template <typename Function, typename AsyncReadStream, typename Allocator,
-      typename MatchCondition, typename ReadHandler>
+  template <typename Function, typename AsyncReadStream,
+      typename DynamicBuffer, typename MatchCondition,
+      typename ReadHandler>
   inline void asio_handler_invoke(const Function& function,
-      read_until_match_op<AsyncReadStream,
-        Allocator, MatchCondition, ReadHandler>* this_handler)
+      read_until_match_op<AsyncReadStream, DynamicBuffer,
+      MatchCondition, ReadHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 } // namespace detail
 
-template <typename AsyncReadStream, typename Allocator,
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename MatchCondition, typename ReadHandler, typename Allocator>
+struct associated_allocator<
+    detail::read_until_match_op<AsyncReadStream,
+      DynamicBuffer, MatchCondition, ReadHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<ReadHandler, Allocator>::type type;
+
+  static type get(
+      const detail::read_until_match_op<AsyncReadStream,
+        DynamicBuffer, MatchCondition, ReadHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<ReadHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename MatchCondition, typename ReadHandler, typename Executor>
+struct associated_executor<
+    detail::read_until_match_op<AsyncReadStream,
+      DynamicBuffer, MatchCondition, ReadHandler>,
+    Executor>
+{
+  typedef typename associated_executor<ReadHandler, Executor>::type type;
+
+  static type get(
+      const detail::read_until_match_op<AsyncReadStream,
+        DynamicBuffer, MatchCondition, ReadHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<ReadHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncReadStream, typename DynamicBuffer,
     typename MatchCondition, typename ReadHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read_until(AsyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
     MatchCondition match_condition, BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
     typename enable_if<is_match_condition<MatchCondition>::value>::type*)
 {
@@ -1128,19 +1424,76 @@ async_read_until(AsyncReadStream& s,
   // not meet the documented type requirements for a ReadHandler.
   BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-  detail::async_result_init<
-    ReadHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+  async_completion<ReadHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::read_until_match_op<AsyncReadStream, Allocator,
-    MatchCondition, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
-      void (boost::system::error_code, std::size_t))>(
-        s, b, match_condition, init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::read_until_match_op<AsyncReadStream,
+    typename decay<DynamicBuffer>::type,
+      MatchCondition, BOOST_ASIO_HANDLER_TYPE(ReadHandler,
+        void (boost::system::error_code, std::size_t))>(
+          s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+            match_condition, init.completion_handler)(
+              boost::system::error_code(), 0, 1);
 
   return init.result.get();
 }
 
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    char delim, BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+{
+  return async_read_until(s, basic_streambuf_ref<Allocator>(b),
+      delim, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+}
+
+template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_STRING_VIEW_PARAM delim,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+{
+  return async_read_until(s, basic_streambuf_ref<Allocator>(b),
+      delim, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+}
+
+#if defined(BOOST_ASIO_HAS_BOOST_REGEX)
+
+template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+{
+  return async_read_until(s, basic_streambuf_ref<Allocator>(b),
+      expr, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+}
+
+#endif // defined(BOOST_ASIO_HAS_BOOST_REGEX)
+
+template <typename AsyncReadStream, typename Allocator,
+    typename MatchCondition, typename ReadHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    MatchCondition match_condition, BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<is_match_condition<MatchCondition>::value>::type*)
+{
+  return async_read_until(s, basic_streambuf_ref<Allocator>(b),
+      match_condition, BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+}
+
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 } // namespace asio
 } // namespace boost
 
diff --git a/include/boost/asio/impl/serial_port_base.ipp b/include/boost/asio/impl/serial_port_base.ipp
index fcb6ce3df4..52ca36229b 100644
--- a/include/boost/asio/impl/serial_port_base.ipp
+++ b/include/boost/asio/impl/serial_port_base.ipp
@@ -38,7 +38,7 @@
 namespace boost {
 namespace asio {
 
-boost::system::error_code serial_port_base::baud_rate::store(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::baud_rate::store(
     BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec) const
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -112,7 +112,7 @@ boost::system::error_code serial_port_base::baud_rate::store(
 # endif
   default:
     ec = boost::asio::error::invalid_argument;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 # if defined(_BSD_SOURCE)
   ::cfsetspeed(&storage, baud);
@@ -122,10 +122,10 @@ boost::system::error_code serial_port_base::baud_rate::store(
 # endif
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code serial_port_base::baud_rate::load(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::baud_rate::load(
     const BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec)
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -200,11 +200,11 @@ boost::system::error_code serial_port_base::baud_rate::load(
   default:
     value_ = 0;
     ec = boost::asio::error::invalid_argument;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 serial_port_base::flow_control::flow_control(
@@ -218,7 +218,7 @@ serial_port_base::flow_control::flow_control(
   }
 }
 
-boost::system::error_code serial_port_base::flow_control::store(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::flow_control::store(
     BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec) const
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -275,17 +275,17 @@ boost::system::error_code serial_port_base::flow_control::store(
     break;
 # else
     ec = boost::asio::error::operation_not_supported;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 # endif
   default:
     break;
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code serial_port_base::flow_control::load(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::flow_control::load(
     const BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec)
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -323,7 +323,7 @@ boost::system::error_code serial_port_base::flow_control::load(
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 serial_port_base::parity::parity(serial_port_base::parity::type t)
@@ -336,7 +336,7 @@ serial_port_base::parity::parity(serial_port_base::parity::type t)
   }
 }
 
-boost::system::error_code serial_port_base::parity::store(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::parity::store(
     BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec) const
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -380,10 +380,10 @@ boost::system::error_code serial_port_base::parity::store(
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code serial_port_base::parity::load(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::parity::load(
     const BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec)
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -417,7 +417,7 @@ boost::system::error_code serial_port_base::parity::load(
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 serial_port_base::stop_bits::stop_bits(
@@ -431,7 +431,7 @@ serial_port_base::stop_bits::stop_bits(
   }
 }
 
-boost::system::error_code serial_port_base::stop_bits::store(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::stop_bits::store(
     BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec) const
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -460,14 +460,14 @@ boost::system::error_code serial_port_base::stop_bits::store(
     break;
   default:
     ec = boost::asio::error::operation_not_supported;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code serial_port_base::stop_bits::load(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::stop_bits::load(
     const BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec)
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -491,7 +491,7 @@ boost::system::error_code serial_port_base::stop_bits::load(
   value_ = (storage.c_cflag & CSTOPB) ? two : one;
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 serial_port_base::character_size::character_size(unsigned int t)
@@ -504,7 +504,7 @@ serial_port_base::character_size::character_size(unsigned int t)
   }
 }
 
-boost::system::error_code serial_port_base::character_size::store(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::character_size::store(
     BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec) const
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -521,10 +521,10 @@ boost::system::error_code serial_port_base::character_size::store(
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code serial_port_base::character_size::load(
+BOOST_ASIO_SYNC_OP_VOID serial_port_base::character_size::load(
     const BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec)
 {
 #if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
@@ -541,7 +541,7 @@ boost::system::error_code serial_port_base::character_size::load(
   }
 #endif
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 } // namespace asio
diff --git a/include/boost/asio/impl/spawn.hpp b/include/boost/asio/impl/spawn.hpp
index a42fc6fbad..ec1ff45d19 100644
--- a/include/boost/asio/impl/spawn.hpp
+++ b/include/boost/asio/impl/spawn.hpp
@@ -16,14 +16,18 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/async_result.hpp>
+#include <boost/asio/bind_executor.hpp>
 #include <boost/asio/detail/atomic_count.hpp>
 #include <boost/asio/detail/handler_alloc_helpers.hpp>
 #include <boost/asio/detail/handler_cont_helpers.hpp>
 #include <boost/asio/detail/handler_invoke_helpers.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
-#include <boost/asio/detail/shared_ptr.hpp>
-#include <boost/asio/handler_type.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/system/system_error.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -64,7 +68,7 @@ namespace detail {
   //private:
     shared_ptr<typename basic_yield_context<Handler>::callee_type> coro_;
     typename basic_yield_context<Handler>::caller_type& ca_;
-    Handler& handler_;
+    Handler handler_;
     atomic_count* ready_;
     boost::system::error_code* ec_;
     T* value_;
@@ -100,7 +104,7 @@ namespace detail {
   //private:
     shared_ptr<typename basic_yield_context<Handler>::callee_type> coro_;
     typename basic_yield_context<Handler>::caller_type& ca_;
-    Handler& handler_;
+    Handler handler_;
     atomic_count* ready_;
     boost::system::error_code* ec_;
   };
@@ -143,10 +147,139 @@ namespace detail {
         function, this_handler->handler_);
   }
 
+  template <typename Handler, typename T>
+  class coro_async_result
+  {
+  public:
+    typedef coro_handler<Handler, T> completion_handler_type;
+    typedef T return_type;
+
+    explicit coro_async_result(completion_handler_type& h)
+      : handler_(h),
+        ca_(h.ca_),
+        ready_(2)
+    {
+      h.ready_ = &ready_;
+      out_ec_ = h.ec_;
+      if (!out_ec_) h.ec_ = &ec_;
+      h.value_ = &value_;
+    }
+
+    return_type get()
+    {
+      // Must not hold shared_ptr to coro while suspended.
+      handler_.coro_.reset();
+
+      if (--ready_ != 0)
+        ca_();
+      if (!out_ec_ && ec_) throw boost::system::system_error(ec_);
+      return BOOST_ASIO_MOVE_CAST(return_type)(value_);
+    }
+
+  private:
+    completion_handler_type& handler_;
+    typename basic_yield_context<Handler>::caller_type& ca_;
+    atomic_count ready_;
+    boost::system::error_code* out_ec_;
+    boost::system::error_code ec_;
+    return_type value_;
+  };
+
+  template <typename Handler>
+  class coro_async_result<Handler, void>
+  {
+  public:
+    typedef coro_handler<Handler, void> completion_handler_type;
+    typedef void return_type;
+
+    explicit coro_async_result(completion_handler_type& h)
+      : handler_(h),
+        ca_(h.ca_),
+        ready_(2)
+    {
+      h.ready_ = &ready_;
+      out_ec_ = h.ec_;
+      if (!out_ec_) h.ec_ = &ec_;
+    }
+
+    void get()
+    {
+      // Must not hold shared_ptr to coro while suspended.
+      handler_.coro_.reset();
+
+      if (--ready_ != 0)
+        ca_();
+      if (!out_ec_ && ec_) throw boost::system::system_error(ec_);
+    }
+
+  private:
+    completion_handler_type& handler_;
+    typename basic_yield_context<Handler>::caller_type& ca_;
+    atomic_count ready_;
+    boost::system::error_code* out_ec_;
+    boost::system::error_code ec_;
+  };
+
 } // namespace detail
 
 #if !defined(GENERATING_DOCUMENTATION)
 
+template <typename Handler, typename ReturnType>
+class async_result<basic_yield_context<Handler>, ReturnType()>
+  : public detail::coro_async_result<Handler, void>
+{
+public:
+  explicit async_result(
+    typename detail::coro_async_result<Handler,
+      void>::completion_handler_type& h)
+    : detail::coro_async_result<Handler, void>(h)
+  {
+  }
+};
+
+template <typename Handler, typename ReturnType, typename Arg1>
+class async_result<basic_yield_context<Handler>, ReturnType(Arg1)>
+  : public detail::coro_async_result<Handler, typename decay<Arg1>::type>
+{
+public:
+  explicit async_result(
+    typename detail::coro_async_result<Handler,
+      typename decay<Arg1>::type>::completion_handler_type& h)
+    : detail::coro_async_result<Handler, Arg1>(h)
+  {
+  }
+};
+
+template <typename Handler, typename ReturnType>
+class async_result<basic_yield_context<Handler>,
+    ReturnType(boost::system::error_code)>
+  : public detail::coro_async_result<Handler, void>
+{
+public:
+  explicit async_result(
+    typename detail::coro_async_result<Handler,
+      void>::completion_handler_type& h)
+    : detail::coro_async_result<Handler, void>(h)
+  {
+  }
+};
+
+template <typename Handler, typename ReturnType, typename Arg2>
+class async_result<basic_yield_context<Handler>,
+    ReturnType(boost::system::error_code, Arg2)>
+  : public detail::coro_async_result<Handler, typename decay<Arg2>::type>
+{
+public:
+  explicit async_result(
+    typename detail::coro_async_result<Handler,
+      typename decay<Arg2>::type>::completion_handler_type& h)
+    : detail::coro_async_result<Handler, Arg2>(h)
+  {
+  }
+};
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
 template <typename Handler, typename ReturnType>
 struct handler_type<basic_yield_context<Handler>, ReturnType()>
 {
@@ -156,7 +289,7 @@ struct handler_type<basic_yield_context<Handler>, ReturnType()>
 template <typename Handler, typename ReturnType, typename Arg1>
 struct handler_type<basic_yield_context<Handler>, ReturnType(Arg1)>
 {
-  typedef detail::coro_handler<Handler, Arg1> type;
+  typedef detail::coro_handler<Handler, typename decay<Arg1>::type> type;
 };
 
 template <typename Handler, typename ReturnType>
@@ -170,74 +303,48 @@ template <typename Handler, typename ReturnType, typename Arg2>
 struct handler_type<basic_yield_context<Handler>,
     ReturnType(boost::system::error_code, Arg2)>
 {
-  typedef detail::coro_handler<Handler, Arg2> type;
+  typedef detail::coro_handler<Handler, typename decay<Arg2>::type> type;
 };
 
 template <typename Handler, typename T>
 class async_result<detail::coro_handler<Handler, T> >
+  : public detail::coro_async_result<Handler, T>
 {
 public:
-  typedef T type;
-
-  explicit async_result(detail::coro_handler<Handler, T>& h)
-    : handler_(h),
-      ca_(h.ca_),
-      ready_(2)
-  {
-    h.ready_ = &ready_;
-    out_ec_ = h.ec_;
-    if (!out_ec_) h.ec_ = &ec_;
-    h.value_ = &value_;
-  }
+  typedef typename detail::coro_async_result<Handler, T>::return_type type;
 
-  type get()
+  explicit async_result(
+    typename detail::coro_async_result<Handler,
+      void>::completion_handler_type& h)
+    : detail::coro_async_result<Handler, T>(h)
   {
-    handler_.coro_.reset(); // Must not hold shared_ptr to coro while suspended.
-    if (--ready_ != 0)
-      ca_();
-    if (!out_ec_ && ec_) throw boost::system::system_error(ec_);
-    return BOOST_ASIO_MOVE_CAST(type)(value_);
   }
-
-private:
-  detail::coro_handler<Handler, T>& handler_;
-  typename basic_yield_context<Handler>::caller_type& ca_;
-  detail::atomic_count ready_;
-  boost::system::error_code* out_ec_;
-  boost::system::error_code ec_;
-  type value_;
 };
 
-template <typename Handler>
-class async_result<detail::coro_handler<Handler, void> >
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+template <typename Handler, typename T, typename Allocator>
+struct associated_allocator<detail::coro_handler<Handler, T>, Allocator>
 {
-public:
-  typedef void type;
+  typedef typename associated_allocator<Handler, Allocator>::type type;
 
-  explicit async_result(detail::coro_handler<Handler, void>& h)
-    : handler_(h),
-      ca_(h.ca_),
-      ready_(2)
+  static type get(const detail::coro_handler<Handler, T>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
   {
-    h.ready_ = &ready_;
-    out_ec_ = h.ec_;
-    if (!out_ec_) h.ec_ = &ec_;
+    return associated_allocator<Handler, Allocator>::get(h.handler_, a);
   }
+};
+
+template <typename Handler, typename T, typename Executor>
+struct associated_executor<detail::coro_handler<Handler, T>, Executor>
+{
+  typedef typename associated_executor<Handler, Executor>::type type;
 
-  void get()
+  static type get(const detail::coro_handler<Handler, T>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
   {
-    handler_.coro_.reset(); // Must not hold shared_ptr to coro while suspended.
-    if (--ready_ != 0)
-      ca_();
-    if (!out_ec_ && ec_) throw boost::system::system_error(ec_);
+    return associated_executor<Handler, Executor>::get(h.handler_, ex);
   }
-
-private:
-  detail::coro_handler<Handler, void>& handler_;
-  typename basic_yield_context<Handler>::caller_type& ca_;
-  detail::atomic_count ready_;
-  boost::system::error_code* out_ec_;
-  boost::system::error_code ec_;
 };
 
 namespace detail {
@@ -270,6 +377,7 @@ namespace detail {
 #endif // !defined(BOOST_COROUTINES_UNIDIRECT) && !defined(BOOST_COROUTINES_V2)
       const basic_yield_context<Handler> yield(
           data->coro_, ca, data->handler_);
+
       (data->function_)(yield);
       if (data->call_handler_)
         (data->handler_)();
@@ -294,22 +402,61 @@ namespace detail {
     boost::coroutines::attributes attributes_;
   };
 
+  template <typename Function, typename Handler, typename Function1>
+  inline void asio_handler_invoke(Function& function,
+      spawn_helper<Handler, Function1>* this_handler)
+  {
+    boost_asio_handler_invoke_helpers::invoke(
+        function, this_handler->data_->handler_);
+  }
+
+  template <typename Function, typename Handler, typename Function1>
+  inline void asio_handler_invoke(const Function& function,
+      spawn_helper<Handler, Function1>* this_handler)
+  {
+    boost_asio_handler_invoke_helpers::invoke(
+        function, this_handler->data_->handler_);
+  }
+
   inline void default_spawn_handler() {}
 
 } // namespace detail
 
+template <typename Function>
+inline void spawn(BOOST_ASIO_MOVE_ARG(Function) function,
+    const boost::coroutines::attributes& attributes)
+{
+  typedef typename decay<Function>::type function_type;
+
+  typename associated_executor<function_type>::type ex(
+      (get_associated_executor)(function));
+
+  boost::asio::spawn(ex, BOOST_ASIO_MOVE_CAST(Function)(function), attributes);
+}
+
 template <typename Handler, typename Function>
 void spawn(BOOST_ASIO_MOVE_ARG(Handler) handler,
     BOOST_ASIO_MOVE_ARG(Function) function,
-    const boost::coroutines::attributes& attributes)
+    const boost::coroutines::attributes& attributes,
+    typename enable_if<!is_executor<typename decay<Handler>::type>::value &&
+      !is_convertible<Handler&, execution_context&>::value>::type*)
 {
-  detail::spawn_helper<Handler, Function> helper;
+  typedef typename decay<Handler>::type handler_type;
+
+  typename associated_executor<handler_type>::type ex(
+      (get_associated_executor)(handler));
+
+  typename associated_allocator<handler_type>::type a(
+      (get_associated_allocator)(handler));
+
+  detail::spawn_helper<handler_type, Function> helper;
   helper.data_.reset(
-      new detail::spawn_data<Handler, Function>(
+      new detail::spawn_data<handler_type, Function>(
         BOOST_ASIO_MOVE_CAST(Handler)(handler), true,
         BOOST_ASIO_MOVE_CAST(Function)(function)));
   helper.attributes_ = attributes;
-  boost_asio_handler_invoke_helpers::invoke(helper, helper.data_->handler_);
+
+  ex.dispatch(helper, a);
 }
 
 template <typename Handler, typename Function>
@@ -318,30 +465,61 @@ void spawn(basic_yield_context<Handler> ctx,
     const boost::coroutines::attributes& attributes)
 {
   Handler handler(ctx.handler_); // Explicit copy that might be moved from.
+
+  typename associated_executor<Handler>::type ex(
+      (get_associated_executor)(handler));
+
+  typename associated_allocator<Handler>::type a(
+      (get_associated_allocator)(handler));
+
   detail::spawn_helper<Handler, Function> helper;
   helper.data_.reset(
       new detail::spawn_data<Handler, Function>(
         BOOST_ASIO_MOVE_CAST(Handler)(handler), false,
         BOOST_ASIO_MOVE_CAST(Function)(function)));
   helper.attributes_ = attributes;
-  boost_asio_handler_invoke_helpers::invoke(helper, helper.data_->handler_);
+
+  ex.dispatch(helper, a);
 }
 
-template <typename Function>
-void spawn(boost::asio::io_service::strand strand,
+template <typename Function, typename Executor>
+inline void spawn(const Executor& ex,
+    BOOST_ASIO_MOVE_ARG(Function) function,
+    const boost::coroutines::attributes& attributes,
+    typename enable_if<is_executor<Executor>::value>::type*)
+{
+  boost::asio::spawn(boost::asio::strand<Executor>(ex),
+      BOOST_ASIO_MOVE_CAST(Function)(function), attributes);
+}
+
+template <typename Function, typename Executor>
+inline void spawn(const strand<Executor>& ex,
     BOOST_ASIO_MOVE_ARG(Function) function,
     const boost::coroutines::attributes& attributes)
 {
-  boost::asio::spawn(strand.wrap(&detail::default_spawn_handler),
+  boost::asio::spawn(boost::asio::bind_executor(
+        ex, &detail::default_spawn_handler),
       BOOST_ASIO_MOVE_CAST(Function)(function), attributes);
 }
 
 template <typename Function>
-void spawn(boost::asio::io_service& io_service,
+inline void spawn(const boost::asio::io_context::strand& s,
     BOOST_ASIO_MOVE_ARG(Function) function,
     const boost::coroutines::attributes& attributes)
 {
-  boost::asio::spawn(boost::asio::io_service::strand(io_service),
+  boost::asio::spawn(boost::asio::bind_executor(
+        s, &detail::default_spawn_handler),
+      BOOST_ASIO_MOVE_CAST(Function)(function), attributes);
+}
+
+template <typename Function, typename ExecutionContext>
+inline void spawn(ExecutionContext& ctx,
+    BOOST_ASIO_MOVE_ARG(Function) function,
+    const boost::coroutines::attributes& attributes,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type*)
+{
+  boost::asio::spawn(ctx.get_executor(),
       BOOST_ASIO_MOVE_CAST(Function)(function), attributes);
 }
 
diff --git a/include/boost/asio/impl/src.hpp b/include/boost/asio/impl/src.hpp
index 7b9a03eda9..ad75cb744d 100644
--- a/include/boost/asio/impl/src.hpp
+++ b/include/boost/asio/impl/src.hpp
@@ -20,9 +20,13 @@
 #endif
 
 #include <boost/asio/impl/error.ipp>
+#include <boost/asio/impl/execution_context.ipp>
+#include <boost/asio/impl/executor.ipp>
 #include <boost/asio/impl/handler_alloc_hook.ipp>
-#include <boost/asio/impl/io_service.ipp>
+#include <boost/asio/impl/io_context.ipp>
 #include <boost/asio/impl/serial_port_base.ipp>
+#include <boost/asio/impl/system_context.ipp>
+#include <boost/asio/impl/thread_pool.ipp>
 #include <boost/asio/detail/impl/buffer_sequence_adapter.ipp>
 #include <boost/asio/detail/impl/descriptor_ops.ipp>
 #include <boost/asio/detail/impl/dev_poll_reactor.ipp>
@@ -30,6 +34,7 @@
 #include <boost/asio/detail/impl/eventfd_select_interrupter.ipp>
 #include <boost/asio/detail/impl/handler_tracking.ipp>
 #include <boost/asio/detail/impl/kqueue_reactor.ipp>
+#include <boost/asio/detail/impl/null_event.ipp>
 #include <boost/asio/detail/impl/pipe_select_interrupter.ipp>
 #include <boost/asio/detail/impl/posix_event.ipp>
 #include <boost/asio/detail/impl/posix_mutex.ipp>
@@ -39,18 +44,19 @@
 #include <boost/asio/detail/impl/reactive_serial_port_service.ipp>
 #include <boost/asio/detail/impl/reactive_socket_service_base.ipp>
 #include <boost/asio/detail/impl/resolver_service_base.ipp>
+#include <boost/asio/detail/impl/scheduler.ipp>
 #include <boost/asio/detail/impl/select_reactor.ipp>
 #include <boost/asio/detail/impl/service_registry.ipp>
 #include <boost/asio/detail/impl/signal_set_service.ipp>
 #include <boost/asio/detail/impl/socket_ops.ipp>
 #include <boost/asio/detail/impl/socket_select_interrupter.ipp>
+#include <boost/asio/detail/impl/strand_executor_service.ipp>
 #include <boost/asio/detail/impl/strand_service.ipp>
-#include <boost/asio/detail/impl/task_io_service.ipp>
 #include <boost/asio/detail/impl/throw_error.ipp>
 #include <boost/asio/detail/impl/timer_queue_ptime.ipp>
 #include <boost/asio/detail/impl/timer_queue_set.ipp>
 #include <boost/asio/detail/impl/win_iocp_handle_service.ipp>
-#include <boost/asio/detail/impl/win_iocp_io_service.ipp>
+#include <boost/asio/detail/impl/win_iocp_io_context.ipp>
 #include <boost/asio/detail/impl/win_iocp_serial_port_service.ipp>
 #include <boost/asio/detail/impl/win_iocp_socket_service_base.ipp>
 #include <boost/asio/detail/impl/win_event.ipp>
@@ -67,6 +73,8 @@
 #include <boost/asio/ip/impl/address_v4.ipp>
 #include <boost/asio/ip/impl/address_v6.ipp>
 #include <boost/asio/ip/impl/host_name.ipp>
+#include <boost/asio/ip/impl/network_v4.ipp>
+#include <boost/asio/ip/impl/network_v6.ipp>
 #include <boost/asio/ip/detail/impl/endpoint.ipp>
 #include <boost/asio/local/detail/impl/endpoint.ipp>
 
diff --git a/include/boost/asio/impl/system_context.ipp b/include/boost/asio/impl/system_context.ipp
new file mode 100644
index 0000000000..86bb44548f
--- /dev/null
+++ b/include/boost/asio/impl/system_context.ipp
@@ -0,0 +1,75 @@
+//
+// impl/system_context.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_SYSTEM_CONTEXT_IPP
+#define BOOST_ASIO_IMPL_SYSTEM_CONTEXT_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/system_context.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+struct system_context::thread_function
+{
+  detail::scheduler* scheduler_;
+
+  void operator()()
+  {
+    boost::system::error_code ec;
+    scheduler_->run(ec);
+  }
+};
+
+system_context::system_context()
+  : scheduler_(use_service<detail::scheduler>(*this))
+{
+  scheduler_.work_started();
+
+  thread_function f = { &scheduler_ };
+  std::size_t num_threads = detail::thread::hardware_concurrency() * 2;
+  threads_.create_threads(f, num_threads ? num_threads : 2);
+}
+
+system_context::~system_context()
+{
+  scheduler_.work_finished();
+  scheduler_.stop();
+  threads_.join();
+}
+
+void system_context::stop()
+{
+  scheduler_.stop();
+}
+
+bool system_context::stopped() const BOOST_ASIO_NOEXCEPT
+{
+  return scheduler_.stopped();
+}
+
+void system_context::join()
+{
+  scheduler_.work_finished();
+  threads_.join();
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_SYSTEM_CONTEXT_IPP
diff --git a/include/boost/asio/impl/system_executor.hpp b/include/boost/asio/impl/system_executor.hpp
new file mode 100644
index 0000000000..c8a0cf4027
--- /dev/null
+++ b/include/boost/asio/impl/system_executor.hpp
@@ -0,0 +1,87 @@
+//
+// impl/system_executor.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_SYSTEM_EXECUTOR_HPP
+#define BOOST_ASIO_IMPL_SYSTEM_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/executor_op.hpp>
+#include <boost/asio/detail/global.hpp>
+#include <boost/asio/detail/recycling_allocator.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/system_context.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+inline system_context& system_executor::context() const BOOST_ASIO_NOEXCEPT
+{
+  return detail::global<system_context>();
+}
+
+template <typename Function, typename Allocator>
+void system_executor::dispatch(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator&) const
+{
+  typename decay<Function>::type tmp(BOOST_ASIO_MOVE_CAST(Function)(f));
+  boost_asio_handler_invoke_helpers::invoke(tmp, tmp);
+}
+
+template <typename Function, typename Allocator>
+void system_executor::post(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  system_context& ctx = detail::global<system_context>();
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((ctx, *p.p,
+        "system_executor", &this->context(), 0, "post"));
+
+  ctx.scheduler_.post_immediate_completion(p.p, false);
+  p.v = p.p = 0;
+}
+
+template <typename Function, typename Allocator>
+void system_executor::defer(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  system_context& ctx = detail::global<system_context>();
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((ctx, *p.p,
+        "system_executor", &this->context(), 0, "defer"));
+
+  ctx.scheduler_.post_immediate_completion(p.p, true);
+  p.v = p.p = 0;
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_SYSTEM_EXECUTOR_HPP
diff --git a/include/boost/asio/impl/thread_pool.hpp b/include/boost/asio/impl/thread_pool.hpp
new file mode 100644
index 0000000000..53a4900d34
--- /dev/null
+++ b/include/boost/asio/impl/thread_pool.hpp
@@ -0,0 +1,129 @@
+//
+// impl/thread_pool.hpp
+// ~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_THREAD_POOL_HPP
+#define BOOST_ASIO_IMPL_THREAD_POOL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/executor_op.hpp>
+#include <boost/asio/detail/fenced_block.hpp>
+#include <boost/asio/detail/recycling_allocator.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/execution_context.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+inline thread_pool::executor_type
+thread_pool::get_executor() BOOST_ASIO_NOEXCEPT
+{
+  return executor_type(*this);
+}
+
+inline thread_pool&
+thread_pool::executor_type::context() const BOOST_ASIO_NOEXCEPT
+{
+  return pool_;
+}
+
+inline void
+thread_pool::executor_type::on_work_started() const BOOST_ASIO_NOEXCEPT
+{
+  pool_.scheduler_.work_started();
+}
+
+inline void thread_pool::executor_type::on_work_finished()
+const BOOST_ASIO_NOEXCEPT
+{
+  pool_.scheduler_.work_finished();
+}
+
+template <typename Function, typename Allocator>
+void thread_pool::executor_type::dispatch(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Invoke immediately if we are already inside the thread pool.
+  if (pool_.scheduler_.can_dispatch())
+  {
+    // Make a local, non-const copy of the function.
+    function_type tmp(BOOST_ASIO_MOVE_CAST(Function)(f));
+
+    detail::fenced_block b(detail::fenced_block::full);
+    boost_asio_handler_invoke_helpers::invoke(tmp, tmp);
+    return;
+  }
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((pool_, *p.p,
+        "thread_pool", &this->context(), 0, "dispatch"));
+
+  pool_.scheduler_.post_immediate_completion(p.p, false);
+  p.v = p.p = 0;
+}
+
+template <typename Function, typename Allocator>
+void thread_pool::executor_type::post(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((pool_, *p.p,
+        "thread_pool", &this->context(), 0, "post"));
+
+  pool_.scheduler_.post_immediate_completion(p.p, false);
+  p.v = p.p = 0;
+}
+
+template <typename Function, typename Allocator>
+void thread_pool::executor_type::defer(
+    BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+{
+  typedef typename decay<Function>::type function_type;
+
+  // Allocate and construct an operation to wrap the function.
+  typedef detail::executor_op<function_type, Allocator> op;
+  typename op::ptr p = { detail::addressof(a), op::ptr::allocate(a), 0 };
+  p.p = new (p.v) op(BOOST_ASIO_MOVE_CAST(Function)(f), a);
+
+  BOOST_ASIO_HANDLER_CREATION((pool_, *p.p,
+        "thread_pool", &this->context(), 0, "defer"));
+
+  pool_.scheduler_.post_immediate_completion(p.p, true);
+  p.v = p.p = 0;
+}
+
+inline bool
+thread_pool::executor_type::running_in_this_thread() const BOOST_ASIO_NOEXCEPT
+{
+  return pool_.scheduler_.can_dispatch();
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_THREAD_POOL_HPP
diff --git a/include/boost/asio/impl/thread_pool.ipp b/include/boost/asio/impl/thread_pool.ipp
new file mode 100644
index 0000000000..43ae029359
--- /dev/null
+++ b/include/boost/asio/impl/thread_pool.ipp
@@ -0,0 +1,78 @@
+//
+// impl/thread_pool.ipp
+// ~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IMPL_THREAD_POOL_IPP
+#define BOOST_ASIO_IMPL_THREAD_POOL_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/thread_pool.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+struct thread_pool::thread_function
+{
+  detail::scheduler* scheduler_;
+
+  void operator()()
+  {
+    boost::system::error_code ec;
+    scheduler_->run(ec);
+  }
+};
+
+thread_pool::thread_pool()
+  : scheduler_(use_service<detail::scheduler>(*this))
+{
+  scheduler_.work_started();
+
+  thread_function f = { &scheduler_ };
+  std::size_t num_threads = detail::thread::hardware_concurrency() * 2;
+  threads_.create_threads(f, num_threads ? num_threads : 2);
+}
+
+thread_pool::thread_pool(std::size_t num_threads)
+  : scheduler_(use_service<detail::scheduler>(*this))
+{
+  scheduler_.work_started();
+
+  thread_function f = { &scheduler_ };
+  threads_.create_threads(f, num_threads);
+}
+
+thread_pool::~thread_pool()
+{
+  stop();
+  join();
+}
+
+void thread_pool::stop()
+{
+  scheduler_.stop();
+}
+
+void thread_pool::join()
+{
+  scheduler_.work_finished();
+  threads_.join();
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_THREAD_POOL_IPP
diff --git a/include/boost/asio/impl/use_future.hpp b/include/boost/asio/impl/use_future.hpp
index c74050ea63..1652855b76 100644
--- a/include/boost/asio/impl/use_future.hpp
+++ b/include/boost/asio/impl/use_future.hpp
@@ -17,11 +17,13 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <future>
+#include <tuple>
 #include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/system/error_code.hpp>
-#include <boost/asio/handler_type.hpp>
+#include <boost/asio/packaged_task.hpp>
 #include <boost/system/system_error.hpp>
-#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/system_executor.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -29,146 +31,877 @@ namespace boost {
 namespace asio {
 namespace detail {
 
-  // Completion handler to adapt a promise as a completion handler.
-  template <typename T>
-  class promise_handler
-  {
-  public:
-    // Construct from use_future special value.
-    template <typename Alloc>
-    promise_handler(use_future_t<Alloc> uf)
-      : promise_(std::allocate_shared<std::promise<T> >(
-            BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator()),
-            std::allocator_arg,
-            BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator())))
+#if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename T, typename F, typename... Args>
+inline void promise_invoke_and_set(std::promise<T>& p,
+    F& f, BOOST_ASIO_MOVE_ARG(Args)... args)
+{
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  {
+    p.set_value(f(BOOST_ASIO_MOVE_CAST(Args)(args)...));
+  }
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+}
+
+template <typename F, typename... Args>
+inline void promise_invoke_and_set(std::promise<void>& p,
+    F& f, BOOST_ASIO_MOVE_ARG(Args)... args)
+{
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  {
+    f(BOOST_ASIO_MOVE_CAST(Args)(args)...);
+    p.set_value();
+  }
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+}
+
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename T, typename F>
+inline void promise_invoke_and_set(std::promise<T>& p, F& f)
+{
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  {
+    p.set_value(f());
+  }
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+}
+
+template <typename F, typename Args>
+inline void promise_invoke_and_set(std::promise<void>& p, F& f)
+{
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  {
+    f();
+    p.set_value();
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  }
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+}
+
+#if defined(BOOST_ASIO_NO_EXCEPTIONS)
+
+#define BOOST_ASIO_PRIVATE_PROMISE_INVOKE_DEF(n) \
+  template <typename T, typename F, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<T>& p, \
+      F& f, BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    p.set_value(f(BOOST_ASIO_VARIADIC_MOVE_ARGS(n))); \
+  } \
+  \
+  template <typename F, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<void>& p, \
+      F& f, BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    f(BOOST_ASIO_VARIADIC_MOVE_ARGS(n)); \
+    p.set_value(); \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_PROMISE_INVOKE_DEF)
+#undef BOOST_ASIO_PRIVATE_PROMISE_INVOKE_DEF
+
+#else // defined(BOOST_ASIO_NO_EXCEPTIONS)
+
+#define BOOST_ASIO_PRIVATE_PROMISE_INVOKE_DEF(n) \
+  template <typename T, typename F, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<T>& p, \
+      F& f, BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    try \
+    { \
+      p.set_value(f(BOOST_ASIO_VARIADIC_MOVE_ARGS(n))); \
+    } \
+    catch (...) \
+    { \
+      p.set_exception(std::current_exception()); \
+    } \
+  } \
+  \
+  template <typename F, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<void>& p, \
+      F& f, BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    try \
+    { \
+      f(BOOST_ASIO_VARIADIC_MOVE_ARGS(n)); \
+      p.set_value(); \
+    } \
+    catch (...) \
+    { \
+      p.set_exception(std::current_exception()); \
+    } \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_PROMISE_INVOKE_DEF)
+#undef BOOST_ASIO_PRIVATE_PROMISE_INVOKE_DEF
+
+#endif // defined(BOOST_ASIO_NO_EXCEPTIONS)
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+// A function object adapter to invoke a nullary function object and capture
+// any exception thrown into a promise.
+template <typename T, typename F>
+class promise_invoker
+{
+public:
+  promise_invoker(const shared_ptr<std::promise<T> >& p,
+      BOOST_ASIO_MOVE_ARG(F) f)
+    : p_(p), f_(BOOST_ASIO_MOVE_CAST(F)(f))
+  {
+  }
+
+  void operator()()
+  {
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+    try
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
     {
+      f_();
     }
-
-    void operator()(T t)
+#if !defined(BOOST_ASIO_NO_EXCEPTIONS)
+    catch (...)
     {
-      promise_->set_value(t);
+      p_->set_exception(std::current_exception());
     }
+#endif // !defined(BOOST_ASIO_NO_EXCEPTIONS)
+  }
+
+private:
+  shared_ptr<std::promise<T> > p_;
+  typename decay<F>::type f_;
+};
+
+// An executor that adapts the system_executor to capture any exeption thrown
+// by a submitted function object and save it into a promise.
+template <typename T>
+class promise_executor
+{
+public:
+  explicit promise_executor(const shared_ptr<std::promise<T> >& p)
+    : p_(p)
+  {
+  }
+
+  execution_context& context() const BOOST_ASIO_NOEXCEPT
+  {
+    return system_executor().context();
+  }
+
+  void on_work_started() const BOOST_ASIO_NOEXCEPT {}
+  void on_work_finished() const BOOST_ASIO_NOEXCEPT {}
+
+  template <typename F, typename A>
+  void dispatch(BOOST_ASIO_MOVE_ARG(F) f, const A&) const
+  {
+    promise_invoker<T, F>(p_, BOOST_ASIO_MOVE_CAST(F)(f))();
+  }
+
+  template <typename F, typename A>
+  void post(BOOST_ASIO_MOVE_ARG(F) f, const A& a) const
+  {
+    system_executor().post(
+        promise_invoker<T, F>(p_, BOOST_ASIO_MOVE_CAST(F)(f)), a);
+  }
+
+  template <typename F, typename A>
+  void defer(BOOST_ASIO_MOVE_ARG(F) f, const A& a) const
+  {
+    system_executor().defer(
+        promise_invoker<T, F>(p_, BOOST_ASIO_MOVE_CAST(F)(f)), a);
+  }
+
+  friend bool operator==(const promise_executor& a,
+      const promise_executor& b) BOOST_ASIO_NOEXCEPT
+  {
+    return a.p_ == b.p_;
+  }
+
+  friend bool operator!=(const promise_executor& a,
+      const promise_executor& b) BOOST_ASIO_NOEXCEPT
+  {
+    return a.p_ != b.p_;
+  }
+
+private:
+  shared_ptr<std::promise<T> > p_;
+};
+
+// The base class for all completion handlers that create promises.
+template <typename T>
+class promise_creator
+{
+public:
+  typedef promise_executor<T> executor_type;
 
-    void operator()(const boost::system::error_code& ec, T t)
+  executor_type get_executor() const BOOST_ASIO_NOEXCEPT
+  {
+    return executor_type(p_);
+  }
+
+  typedef std::future<T> future_type;
+
+  future_type get_future()
+  {
+    return p_->get_future();
+  }
+
+protected:
+  template <typename Allocator>
+  void create_promise(const Allocator& a)
+  {
+    BOOST_ASIO_REBIND_ALLOC(Allocator, char) b(a);
+    p_ = std::allocate_shared<std::promise<T>>(b, std::allocator_arg, b);
+  }
+
+  shared_ptr<std::promise<T> > p_;
+};
+
+// For completion signature void().
+class promise_handler_0
+  : public promise_creator<void>
+{
+public:
+  void operator()()
+  {
+    this->p_->set_value();
+  }
+};
+
+// For completion signature void(error_code).
+class promise_handler_ec_0
+  : public promise_creator<void>
+{
+public:
+  void operator()(const boost::system::error_code& ec)
+  {
+    if (ec)
     {
-      if (ec)
-        promise_->set_exception(
-            std::make_exception_ptr(
-              boost::system::system_error(ec)));
-      else
-        promise_->set_value(t);
+      this->p_->set_exception(
+          std::make_exception_ptr(
+            boost::system::system_error(ec)));
     }
-
-  //private:
-    std::shared_ptr<std::promise<T> > promise_;
-  };
-
-  // Completion handler to adapt a void promise as a completion handler.
-  template <>
-  class promise_handler<void>
-  {
-  public:
-    // Construct from use_future special value. Used during rebinding.
-    template <typename Alloc>
-    promise_handler(use_future_t<Alloc> uf)
-      : promise_(std::allocate_shared<std::promise<void> >(
-            BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator()),
-            std::allocator_arg,
-            BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator())))
+    else
     {
+      this->p_->set_value();
     }
+  }
+};
 
-    void operator()()
+// For completion signature void(exception_ptr).
+class promise_handler_ex_0
+  : public promise_creator<void>
+{
+public:
+  void operator()(const std::exception_ptr& ex)
+  {
+    if (ex)
+    {
+      this->p_->set_exception(ex);
+    }
+    else
     {
-      promise_->set_value();
+      this->p_->set_value();
     }
+  }
+};
+
+// For completion signature void(T).
+template <typename T>
+class promise_handler_1
+  : public promise_creator<T>
+{
+public:
+  template <typename Arg>
+  void operator()(BOOST_ASIO_MOVE_ARG(Arg) arg)
+  {
+    this->p_->set_value(BOOST_ASIO_MOVE_CAST(Arg)(arg));
+  }
+};
 
-    void operator()(const boost::system::error_code& ec)
+// For completion signature void(error_code, T).
+template <typename T>
+class promise_handler_ec_1
+  : public promise_creator<T>
+{
+public:
+  template <typename Arg>
+  void operator()(const boost::system::error_code& ec,
+      BOOST_ASIO_MOVE_ARG(Arg) arg)
+  {
+    if (ec)
     {
-      if (ec)
-        promise_->set_exception(
-            std::make_exception_ptr(
-              boost::system::system_error(ec)));
-      else
-        promise_->set_value();
+      this->p_->set_exception(
+          std::make_exception_ptr(
+            boost::system::system_error(ec)));
     }
+    else
+      this->p_->set_value(BOOST_ASIO_MOVE_CAST(Arg)(arg));
+  }
+};
 
-  //private:
-    std::shared_ptr<std::promise<void> > promise_;
-  };
+// For completion signature void(exception_ptr, T).
+template <typename T>
+class promise_handler_ex_1
+  : public promise_creator<T>
+{
+public:
+  template <typename Arg>
+  void operator()(const std::exception_ptr& ex,
+      BOOST_ASIO_MOVE_ARG(Arg) arg)
+  {
+    if (ex)
+      this->p_->set_exception(ex);
+    else
+      this->p_->set_value(BOOST_ASIO_MOVE_CAST(Arg)(arg));
+  }
+};
 
-  // Ensure any exceptions thrown from the handler are propagated back to the
-  // caller via the future.
-  template <typename Function, typename T>
-  void asio_handler_invoke(Function f, promise_handler<T>* h)
+// For completion signature void(T1, ..., Tn);
+template <typename T>
+class promise_handler_n
+  : public promise_creator<T>
+{
+public:
+#if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename... Args>
+  void operator()(BOOST_ASIO_MOVE_ARG(Args)... args)
   {
-    std::shared_ptr<std::promise<T> > p(h->promise_);
-    try
+    this->p_->set_value(
+        std::forward_as_tuple(
+          BOOST_ASIO_MOVE_CAST(Args)(args)...));
+  }
+
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+#define BOOST_ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    this->p_->set_value( \
+        std::forward_as_tuple( \
+          BOOST_ASIO_VARIADIC_MOVE_ARGS(n))); \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_CALL_OP_DEF)
+#undef BOOST_ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+};
+
+// For completion signature void(error_code, T1, ..., Tn);
+template <typename T>
+class promise_handler_ec_n
+  : public promise_creator<T>
+{
+public:
+#if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename... Args>
+  void operator()(const boost::system::error_code& ec,
+      BOOST_ASIO_MOVE_ARG(Args)... args)
+  {
+    if (ec)
     {
-      f();
+      this->p_->set_exception(
+          std::make_exception_ptr(
+            boost::system::system_error(ec)));
     }
-    catch (...)
+    else
     {
-      p->set_exception(std::current_exception());
+      this->p_->set_value(
+          std::forward_as_tuple(
+            BOOST_ASIO_MOVE_CAST(Args)(args)...));
     }
   }
 
-} // namespace detail
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 
-#if !defined(GENERATING_DOCUMENTATION)
+#define BOOST_ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(const boost::system::error_code& ec, \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    if (ec) \
+    { \
+      this->p_->set_exception( \
+          std::make_exception_ptr( \
+            boost::system::system_error(ec))); \
+    } \
+    else \
+    { \
+      this->p_->set_value( \
+          std::forward_as_tuple( \
+            BOOST_ASIO_VARIADIC_MOVE_ARGS(n))); \
+    } \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_CALL_OP_DEF)
+#undef BOOST_ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+};
 
-// Handler traits specialisation for promise_handler.
+// For completion signature void(exception_ptr, T1, ..., Tn);
 template <typename T>
-class async_result<detail::promise_handler<T> >
+class promise_handler_ex_n
+  : public promise_creator<T>
 {
 public:
-  // The initiating function will return a future.
-  typedef std::future<T> type;
+#if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
 
-  // Constructor creates a new promise for the async operation, and obtains the
-  // corresponding future.
-  explicit async_result(detail::promise_handler<T>& h)
+  template <typename... Args>
+  void operator()(const std::exception_ptr& ex,
+      BOOST_ASIO_MOVE_ARG(Args)... args)
   {
-    value_ = h.promise_->get_future();
+    if (ex)
+      this->p_->set_exception(ex);
+    else
+    {
+      this->p_->set_value(
+          std::forward_as_tuple(
+            BOOST_ASIO_MOVE_CAST(Args)(args)...));
+    }
   }
 
-  // Obtain the future to be returned from the initiating function.
-  type get() { return std::move(value_); }
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+#define BOOST_ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(const std::exception_ptr& ex, \
+      BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    if (ex) \
+      this->p_->set_exception(ex); \
+    else \
+    { \
+      this->p_->set_value( \
+          std::forward_as_tuple( \
+            BOOST_ASIO_VARIADIC_MOVE_ARGS(n))); \
+    } \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_CALL_OP_DEF)
+#undef BOOST_ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+};
+
+// Helper template to choose the appropriate concrete promise handler
+// implementation based on the supplied completion signature.
+template <typename> class promise_handler_selector;
+
+template <>
+class promise_handler_selector<void()>
+  : public promise_handler_0 {};
+
+template <>
+class promise_handler_selector<void(boost::system::error_code)>
+  : public promise_handler_ec_0 {};
+
+template <>
+class promise_handler_selector<void(std::exception_ptr)>
+  : public promise_handler_ex_0 {};
+
+template <typename Arg>
+class promise_handler_selector<void(Arg)>
+  : public promise_handler_1<Arg> {};
+
+template <typename Arg>
+class promise_handler_selector<void(boost::system::error_code, Arg)>
+  : public promise_handler_ec_1<Arg> {};
+
+template <typename Arg>
+class promise_handler_selector<void(std::exception_ptr, Arg)>
+  : public promise_handler_ex_1<Arg> {};
+
+template <typename... Arg>
+class promise_handler_selector<void(Arg...)>
+  : public promise_handler_n<std::tuple<Arg...> > {};
+
+template <typename... Arg>
+class promise_handler_selector<void(boost::system::error_code, Arg...)>
+  : public promise_handler_ec_n<std::tuple<Arg...> > {};
+
+template <typename... Arg>
+class promise_handler_selector<void(std::exception_ptr, Arg...)>
+  : public promise_handler_ex_n<std::tuple<Arg...> > {};
+
+// Completion handlers produced from the use_future completion token, when not
+// using use_future::operator().
+template <typename Signature, typename Allocator>
+class promise_handler
+  : public promise_handler_selector<Signature>
+{
+public:
+  typedef Allocator allocator_type;
+  typedef void result_type;
+
+  promise_handler(use_future_t<Allocator> u)
+    : allocator_(u.get_allocator())
+  {
+    this->create_promise(allocator_);
+  }
+
+  allocator_type get_allocator() const BOOST_ASIO_NOEXCEPT
+  {
+    return allocator_;
+  }
 
 private:
-  type value_;
+  Allocator allocator_;
 };
 
-// Handler type specialisation for use_future.
-template <typename Allocator, typename ReturnType>
-struct handler_type<use_future_t<Allocator>, ReturnType()>
+template <typename Function, typename Signature, typename Allocator>
+inline void asio_handler_invoke(Function& f,
+    promise_handler<Signature, Allocator>* h)
+{
+  typename promise_handler<Signature, Allocator>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(BOOST_ASIO_MOVE_CAST(Function)(f), std::allocator<void>());
+}
+
+template <typename Function, typename Signature, typename Allocator>
+inline void asio_handler_invoke(const Function& f,
+    promise_handler<Signature, Allocator>* h)
+{
+  typename promise_handler<Signature, Allocator>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(f, std::allocator<void>());
+}
+
+// Helper base class for async_result specialisation.
+template <typename Signature, typename Allocator>
+class promise_async_result
 {
-  typedef detail::promise_handler<void> type;
+public:
+  typedef promise_handler<Signature, Allocator> completion_handler_type;
+  typedef typename completion_handler_type::future_type return_type;
+
+  explicit promise_async_result(completion_handler_type& h)
+    : future_(h.get_future())
+  {
+  }
+
+  return_type get()
+  {
+    return BOOST_ASIO_MOVE_CAST(return_type)(future_);
+  }
+
+private:
+  return_type future_;
 };
 
-// Handler type specialisation for use_future.
-template <typename Allocator, typename ReturnType, typename Arg1>
-struct handler_type<use_future_t<Allocator>, ReturnType(Arg1)>
+// Return value from use_future::operator().
+template <typename Function, typename Allocator>
+class packaged_token
 {
-  typedef detail::promise_handler<Arg1> type;
+public:
+  packaged_token(Function f, const Allocator& a)
+    : function_(BOOST_ASIO_MOVE_CAST(Function)(f)),
+      allocator_(a)
+  {
+  }
+
+//private:
+  Function function_;
+  Allocator allocator_;
 };
 
-// Handler type specialisation for use_future.
-template <typename Allocator, typename ReturnType>
-struct handler_type<use_future_t<Allocator>,
-    ReturnType(boost::system::error_code)>
+// Completion handlers produced from the use_future completion token, when
+// using use_future::operator().
+template <typename Function, typename Allocator, typename Result>
+class packaged_handler
+  : public promise_creator<Result>
 {
-  typedef detail::promise_handler<void> type;
+public:
+  typedef Allocator allocator_type;
+  typedef void result_type;
+
+  packaged_handler(packaged_token<Function, Allocator> t)
+    : function_(BOOST_ASIO_MOVE_CAST(Function)(t.function_)),
+      allocator_(t.allocator_)
+  {
+    this->create_promise(allocator_);
+  }
+
+  allocator_type get_allocator() const BOOST_ASIO_NOEXCEPT
+  {
+    return allocator_;
+  }
+
+#if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename... Args>
+  void operator()(BOOST_ASIO_MOVE_ARG(Args)... args)
+  {
+    (promise_invoke_and_set)(*this->p_,
+        function_, BOOST_ASIO_MOVE_CAST(Args)(args)...);
+  }
+
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+  void operator()()
+  {
+    (promise_invoke_and_set)(*this->p_, function_);
+  }
+
+#define BOOST_ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(BOOST_ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    (promise_invoke_and_set)(*this->p_, \
+        function_, BOOST_ASIO_VARIADIC_MOVE_ARGS(n)); \
+  } \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_CALL_OP_DEF)
+#undef BOOST_ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+private:
+  Function function_;
+  Allocator allocator_;
 };
 
-// Handler type specialisation for use_future.
-template <typename Allocator, typename ReturnType, typename Arg2>
-struct handler_type<use_future_t<Allocator>,
-    ReturnType(boost::system::error_code, Arg2)>
+template <typename Function,
+    typename Function1, typename Allocator, typename Result>
+inline void asio_handler_invoke(Function& f,
+    packaged_handler<Function1, Allocator, Result>* h)
 {
-  typedef detail::promise_handler<Arg2> type;
+  typename packaged_handler<Function1, Allocator, Result>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(BOOST_ASIO_MOVE_CAST(Function)(f), std::allocator<void>());
+}
+
+template <typename Function,
+    typename Function1, typename Allocator, typename Result>
+inline void asio_handler_invoke(const Function& f,
+    packaged_handler<Function1, Allocator, Result>* h)
+{
+  typename packaged_handler<Function1, Allocator, Result>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(f, std::allocator<void>());
+}
+
+// Helper base class for async_result specialisation.
+template <typename Function, typename Allocator, typename Result>
+class packaged_async_result
+{
+public:
+  typedef packaged_handler<Function, Allocator, Result> completion_handler_type;
+  typedef typename completion_handler_type::future_type return_type;
+
+  explicit packaged_async_result(completion_handler_type& h)
+    : future_(h.get_future())
+  {
+  }
+
+  return_type get()
+  {
+    return BOOST_ASIO_MOVE_CAST(return_type)(future_);
+  }
+
+private:
+  return_type future_;
 };
 
+} // namespace detail
+
+template <typename Allocator> template <typename Function>
+inline detail::packaged_token<typename decay<Function>::type, Allocator>
+use_future_t<Allocator>::operator()(BOOST_ASIO_MOVE_ARG(Function) f) const
+{
+  return detail::packaged_token<typename decay<Function>::type, Allocator>(
+      BOOST_ASIO_MOVE_CAST(Function)(f), allocator_);
+}
+
+#if !defined(GENERATING_DOCUMENTATION)
+
+#if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename Allocator, typename Result, typename... Args>
+class async_result<use_future_t<Allocator>, Result(Args...)>
+  : public detail::promise_async_result<
+      void(typename decay<Args>::type...), Allocator>
+{
+public:
+  explicit async_result(
+    typename detail::promise_async_result<void(typename decay<Args>::type...),
+      Allocator>::completion_handler_type& h)
+    : detail::promise_async_result<
+        void(typename decay<Args>::type...), Allocator>(h)
+  {
+  }
+};
+
+template <typename Function, typename Allocator,
+    typename Result, typename... Args>
+class async_result<detail::packaged_token<Function, Allocator>, Result(Args...)>
+  : public detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function(Args...)>::type>
+{
+public:
+  explicit async_result(
+    typename detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function(Args...)>::type>::completion_handler_type& h)
+    : detail::packaged_async_result<Function, Allocator,
+        typename result_of<Function(Args...)>::type>(h)
+  {
+  }
+};
+
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename Allocator, typename Result>
+class async_result<use_future_t<Allocator>, Result()>
+  : public detail::promise_async_result<void(), Allocator>
+{
+public:
+  explicit async_result(
+    typename detail::promise_async_result<
+      void(), Allocator>::completion_handler_type& h)
+    : detail::promise_async_result<void(), Allocator>(h)
+  {
+  }
+};
+
+template <typename Function, typename Allocator, typename Result>
+class async_result<detail::packaged_token<Function, Allocator>, Result()>
+  : public detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function()>::type>
+{
+public:
+  explicit async_result(
+    typename detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function()>::type>::completion_handler_type& h)
+    : detail::packaged_async_result<Function, Allocator,
+        typename result_of<Function()>::type>(h)
+  {
+  }
+};
+
+#define BOOST_ASIO_PRIVATE_ASYNC_RESULT_DEF(n) \
+  template <typename Allocator, \
+      typename Result, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  class async_result<use_future_t<Allocator>, \
+      Result(BOOST_ASIO_VARIADIC_TARGS(n))> \
+    : public detail::promise_async_result< \
+        void(BOOST_ASIO_VARIADIC_DECAY(n)), Allocator> \
+  { \
+  public: \
+    explicit async_result( \
+      typename detail::promise_async_result< \
+        void(BOOST_ASIO_VARIADIC_DECAY(n)), \
+        Allocator>::completion_handler_type& h) \
+      : detail::promise_async_result< \
+          void(BOOST_ASIO_VARIADIC_DECAY(n)), Allocator>(h) \
+    { \
+    } \
+  }; \
+  \
+  template <typename Function, typename Allocator, \
+      typename Result, BOOST_ASIO_VARIADIC_TPARAMS(n)> \
+  class async_result<detail::packaged_token<Function, Allocator>, \
+      Result(BOOST_ASIO_VARIADIC_TARGS(n))> \
+    : public detail::packaged_async_result<Function, Allocator, \
+        typename result_of<Function(BOOST_ASIO_VARIADIC_TARGS(n))>::type> \
+  { \
+  public: \
+    explicit async_result( \
+      typename detail::packaged_async_result<Function, Allocator, \
+        typename result_of<Function(BOOST_ASIO_VARIADIC_TARGS(n))>::type \
+        >::completion_handler_type& h) \
+      : detail::packaged_async_result<Function, Allocator, \
+          typename result_of<Function(BOOST_ASIO_VARIADIC_TARGS(n))>::type>(h) \
+    { \
+    } \
+  }; \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_ASYNC_RESULT_DEF)
+#undef BOOST_ASIO_PRIVATE_ASYNC_RESULT_DEF
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+template <typename Allocator, typename Signature>
+struct handler_type<use_future_t<Allocator>, Signature>
+{
+  typedef typename async_result<use_future_t<Allocator>,
+    Signature>::completion_handler_type type;
+};
+
+template <typename Signature, typename Allocator>
+class async_result<detail::promise_handler<Signature, Allocator> >
+  : public detail::promise_async_result<Signature, Allocator>
+{
+public:
+  typedef typename detail::promise_async_result<
+    Signature, Allocator>::return_type type;
+
+  explicit async_result(
+    typename detail::promise_async_result<
+      Signature, Allocator>::completion_handler_type& h)
+    : detail::promise_async_result<Signature, Allocator>(h)
+  {
+  }
+};
+
+template <typename Function, typename Allocator, typename Signature>
+struct handler_type<detail::packaged_token<Function, Allocator>, Signature>
+{
+  typedef typename async_result<detail::packaged_token<Function, Allocator>,
+    Signature>::completion_handler_type type;
+};
+
+template <typename Function, typename Allocator, typename Result>
+class async_result<detail::packaged_handler<Function, Allocator, Result> >
+  : public detail::packaged_async_result<Function, Allocator, Result>
+{
+public:
+  typedef typename detail::packaged_async_result<
+    Function, Allocator, Result>::return_type type;
+
+  explicit async_result(
+    typename detail::packaged_async_result<
+      Function, Allocator, Result>::completion_handler_type& h)
+    : detail::packaged_async_result<Function, Allocator, Result>(h)
+  {
+  }
+};
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
 #endif // !defined(GENERATING_DOCUMENTATION)
 
 } // namespace asio
diff --git a/include/boost/asio/impl/write.hpp b/include/boost/asio/impl/write.hpp
index 84313fed09..8048380f9f 100644
--- a/include/boost/asio/impl/write.hpp
+++ b/include/boost/asio/impl/write.hpp
@@ -15,6 +15,8 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/completion_condition.hpp>
 #include <boost/asio/detail/array_fwd.hpp>
@@ -33,30 +35,46 @@
 namespace boost {
 namespace asio {
 
-template <typename SyncWriteStream, typename ConstBufferSequence,
-    typename CompletionCondition>
-std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
-    CompletionCondition completion_condition, boost::system::error_code& ec)
+namespace detail
 {
-  ec = boost::system::error_code();
-  boost::asio::detail::consuming_buffers<
-    const_buffer, ConstBufferSequence> tmp(buffers);
-  std::size_t total_transferred = 0;
-  tmp.prepare(detail::adapt_completion_condition_result(
-        completion_condition(ec, total_transferred)));
-  while (tmp.begin() != tmp.end())
+  template <typename SyncWriteStream, typename ConstBufferSequence,
+      typename ConstBufferIterator, typename CompletionCondition>
+  std::size_t write_buffer_sequence(SyncWriteStream& s,
+      const ConstBufferSequence& buffers, const ConstBufferIterator&,
+      CompletionCondition completion_condition, boost::system::error_code& ec)
   {
-    std::size_t bytes_transferred = s.write_some(tmp, ec);
-    tmp.consume(bytes_transferred);
-    total_transferred += bytes_transferred;
-    tmp.prepare(detail::adapt_completion_condition_result(
-          completion_condition(ec, total_transferred)));
+    ec = boost::system::error_code();
+    boost::asio::detail::consuming_buffers<const_buffer,
+        ConstBufferSequence, ConstBufferIterator> tmp(buffers);
+    while (!tmp.empty())
+    {
+      if (std::size_t max_size = detail::adapt_completion_condition_result(
+            completion_condition(ec, tmp.total_consumed())))
+        tmp.consume(s.write_some(tmp.prepare(max_size), ec));
+      else
+        break;
+    }
+    return tmp.total_consumed();;
   }
-  return total_transferred;
+} // namespace detail
+
+template <typename SyncWriteStream, typename ConstBufferSequence,
+    typename CompletionCondition>
+inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type*)
+{
+  return detail::write_buffer_sequence(s, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition, ec);
 }
 
 template <typename SyncWriteStream, typename ConstBufferSequence>
-inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers)
+inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type*)
 {
   boost::system::error_code ec;
   std::size_t bytes_transferred = write(s, buffers, transfer_all(), ec);
@@ -66,7 +84,10 @@ inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers)
 
 template <typename SyncWriteStream, typename ConstBufferSequence>
 inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
-    boost::system::error_code& ec)
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type*)
 {
   return write(s, buffers, transfer_all(), ec);
 }
@@ -74,7 +95,10 @@ inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
 template <typename SyncWriteStream, typename ConstBufferSequence,
     typename CompletionCondition>
 inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
-    CompletionCondition completion_condition)
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type*)
 {
   boost::system::error_code ec;
   std::size_t bytes_transferred = write(s, buffers, completion_condition, ec);
@@ -82,35 +106,92 @@ inline std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
   return bytes_transferred;
 }
 
-#if !defined(BOOST_ASIO_NO_IOSTREAM)
-
-template <typename SyncWriteStream, typename Allocator,
+template <typename SyncWriteStream, typename DynamicBuffer,
     typename CompletionCondition>
 std::size_t write(SyncWriteStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
-    CompletionCondition completion_condition, boost::system::error_code& ec)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
 {
+  typename decay<DynamicBuffer>::type b(
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers));
+
   std::size_t bytes_transferred = write(s, b.data(), completion_condition, ec);
   b.consume(bytes_transferred);
   return bytes_transferred;
 }
 
-template <typename SyncWriteStream, typename Allocator>
+template <typename SyncWriteStream, typename DynamicBuffer>
 inline std::size_t write(SyncWriteStream& s,
-    boost::asio::basic_streambuf<Allocator>& b)
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
 {
   boost::system::error_code ec;
-  std::size_t bytes_transferred = write(s, b, transfer_all(), ec);
+  std::size_t bytes_transferred = write(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      transfer_all(), ec);
   boost::asio::detail::throw_error(ec, "write");
   return bytes_transferred;
 }
 
+template <typename SyncWriteStream, typename DynamicBuffer>
+inline std::size_t write(SyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
+{
+  return write(s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      transfer_all(), ec);
+}
+
+template <typename SyncWriteStream, typename DynamicBuffer,
+    typename CompletionCondition>
+inline std::size_t write(SyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
+{
+  boost::system::error_code ec;
+  std::size_t bytes_transferred = write(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      completion_condition, ec);
+  boost::asio::detail::throw_error(ec, "write");
+  return bytes_transferred;
+}
+
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+template <typename SyncWriteStream, typename Allocator,
+    typename CompletionCondition>
+inline std::size_t write(SyncWriteStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    CompletionCondition completion_condition, boost::system::error_code& ec)
+{
+  return write(s, basic_streambuf_ref<Allocator>(b), completion_condition, ec);
+}
+
+template <typename SyncWriteStream, typename Allocator>
+inline std::size_t write(SyncWriteStream& s,
+    boost::asio::basic_streambuf<Allocator>& b)
+{
+  return write(s, basic_streambuf_ref<Allocator>(b));
+}
+
 template <typename SyncWriteStream, typename Allocator>
 inline std::size_t write(SyncWriteStream& s,
     boost::asio::basic_streambuf<Allocator>& b,
     boost::system::error_code& ec)
 {
-  return write(s, b, transfer_all(), ec);
+  return write(s, basic_streambuf_ref<Allocator>(b), ec);
 }
 
 template <typename SyncWriteStream, typename Allocator,
@@ -119,18 +200,17 @@ inline std::size_t write(SyncWriteStream& s,
     boost::asio::basic_streambuf<Allocator>& b,
     CompletionCondition completion_condition)
 {
-  boost::system::error_code ec;
-  std::size_t bytes_transferred = write(s, b, completion_condition, ec);
-  boost::asio::detail::throw_error(ec, "write");
-  return bytes_transferred;
+  return write(s, basic_streambuf_ref<Allocator>(b), completion_condition);
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 namespace detail
 {
   template <typename AsyncWriteStream, typename ConstBufferSequence,
-      typename CompletionCondition, typename WriteHandler>
+      typename ConstBufferIterator, typename CompletionCondition,
+      typename WriteHandler>
   class write_op
     : detail::base_from_completion_cond<CompletionCondition>
   {
@@ -142,7 +222,6 @@ namespace detail
         stream_(stream),
         buffers_(buffers),
         start_(0),
-        total_transferred_(0),
         handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
     {
     }
@@ -153,7 +232,6 @@ namespace detail
         stream_(other.stream_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(other.handler_)
     {
     }
@@ -163,7 +241,6 @@ namespace detail
         stream_(other.stream_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
     {
     }
@@ -172,362 +249,39 @@ namespace detail
     void operator()(const boost::system::error_code& ec,
         std::size_t bytes_transferred, int start = 0)
     {
+      std::size_t max_size;
       switch (start_ = start)
       {
         case 1:
-        buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-        for (;;)
+        max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        do
         {
-          stream_.async_write_some(buffers_,
+          stream_.async_write_some(buffers_.prepare(max_size),
               BOOST_ASIO_MOVE_CAST(write_op)(*this));
           return; default:
-          total_transferred_ += bytes_transferred;
           buffers_.consume(bytes_transferred);
-          buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-          if ((!ec && bytes_transferred == 0)
-              || buffers_.begin() == buffers_.end())
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncWriteStream& stream_;
-    boost::asio::detail::consuming_buffers<
-      const_buffer, ConstBufferSequence> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-  template <typename AsyncWriteStream,
-      typename CompletionCondition, typename WriteHandler>
-  class write_op<AsyncWriteStream, boost::asio::mutable_buffers_1,
-      CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_op(AsyncWriteStream& stream,
-        const boost::asio::mutable_buffers_1& buffers,
-        CompletionCondition completion_condition,
-        WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        stream_(stream),
-        buffer_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_op(const write_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_op(write_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          stream_.async_write_some(
-              boost::asio::buffer(buffer_ + total_transferred_, n),
-              BOOST_ASIO_MOVE_CAST(write_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == boost::asio::buffer_size(buffer_))
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncWriteStream& stream_;
-    boost::asio::mutable_buffer buffer_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-  template <typename AsyncWriteStream,
-      typename CompletionCondition, typename WriteHandler>
-  class write_op<AsyncWriteStream, boost::asio::const_buffers_1,
-      CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_op(AsyncWriteStream& stream,
-        const boost::asio::const_buffers_1& buffers,
-        CompletionCondition completion_condition,
-        WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        stream_(stream),
-        buffer_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_op(const write_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_op(write_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          stream_.async_write_some(
-              boost::asio::buffer(buffer_ + total_transferred_, n),
-              BOOST_ASIO_MOVE_CAST(write_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == boost::asio::buffer_size(buffer_))
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncWriteStream& stream_;
-    boost::asio::const_buffer buffer_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-  template <typename AsyncWriteStream, typename Elem,
-      typename CompletionCondition, typename WriteHandler>
-  class write_op<AsyncWriteStream, boost::array<Elem, 2>,
-      CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_op(AsyncWriteStream& stream, const boost::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        stream_(stream),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_op(const write_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_op(write_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          boost::array<boost::asio::const_buffer, 2> >::type bufs = {{
-        boost::asio::const_buffer(buffers_[0]),
-        boost::asio::const_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          stream_.async_write_some(bufs, BOOST_ASIO_MOVE_CAST(write_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
+          if ((!ec && bytes_transferred == 0) || buffers_.empty())
             break;
-        }
+          max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        } while (max_size > 0);
 
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
+        handler_(ec, buffers_.total_consumed());
       }
     }
 
   //private:
     AsyncWriteStream& stream_;
-    boost::array<Elem, 2> buffers_;
+    boost::asio::detail::consuming_buffers<const_buffer,
+        ConstBufferSequence, ConstBufferIterator> buffers_;
     int start_;
-    std::size_t total_transferred_;
     WriteHandler handler_;
   };
 
-#if defined(BOOST_ASIO_HAS_STD_ARRAY)
-
-  template <typename AsyncWriteStream, typename Elem,
-      typename CompletionCondition, typename WriteHandler>
-  class write_op<AsyncWriteStream, std::array<Elem, 2>,
-      CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_op(AsyncWriteStream& stream, const std::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        stream_(stream),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_op(const write_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_op(write_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        stream_(other.stream_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          std::array<boost::asio::const_buffer, 2> >::type bufs = {{
-        boost::asio::const_buffer(buffers_[0]),
-        boost::asio::const_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          stream_.async_write_some(bufs, BOOST_ASIO_MOVE_CAST(write_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncWriteStream& stream_;
-    std::array<Elem, 2> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-#endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
-
   template <typename AsyncWriteStream, typename ConstBufferSequence,
-      typename CompletionCondition, typename WriteHandler>
+      typename ConstBufferIterator, typename CompletionCondition,
+      typename WriteHandler>
   inline void* asio_handler_allocate(std::size_t size,
-      write_op<AsyncWriteStream, ConstBufferSequence,
+      write_op<AsyncWriteStream, ConstBufferSequence, ConstBufferIterator,
         CompletionCondition, WriteHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
@@ -535,9 +289,10 @@ namespace detail
   }
 
   template <typename AsyncWriteStream, typename ConstBufferSequence,
-      typename CompletionCondition, typename WriteHandler>
+      typename ConstBufferIterator, typename CompletionCondition,
+      typename WriteHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
-      write_op<AsyncWriteStream, ConstBufferSequence,
+      write_op<AsyncWriteStream, ConstBufferSequence, ConstBufferIterator,
         CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
@@ -545,9 +300,10 @@ namespace detail
   }
 
   template <typename AsyncWriteStream, typename ConstBufferSequence,
-      typename CompletionCondition, typename WriteHandler>
+      typename ConstBufferIterator, typename CompletionCondition,
+      typename WriteHandler>
   inline bool asio_handler_is_continuation(
-      write_op<AsyncWriteStream, ConstBufferSequence,
+      write_op<AsyncWriteStream, ConstBufferSequence, ConstBufferIterator,
         CompletionCondition, WriteHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
@@ -556,10 +312,10 @@ namespace detail
   }
 
   template <typename Function, typename AsyncWriteStream,
-      typename ConstBufferSequence, typename CompletionCondition,
-      typename WriteHandler>
+      typename ConstBufferSequence, typename ConstBufferIterator,
+      typename CompletionCondition, typename WriteHandler>
   inline void asio_handler_invoke(Function& function,
-      write_op<AsyncWriteStream, ConstBufferSequence,
+      write_op<AsyncWriteStream, ConstBufferSequence, ConstBufferIterator,
         CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
@@ -567,38 +323,94 @@ namespace detail
   }
 
   template <typename Function, typename AsyncWriteStream,
-      typename ConstBufferSequence, typename CompletionCondition,
-      typename WriteHandler>
+      typename ConstBufferSequence, typename ConstBufferIterator,
+      typename CompletionCondition, typename WriteHandler>
   inline void asio_handler_invoke(const Function& function,
-      write_op<AsyncWriteStream, ConstBufferSequence,
+      write_op<AsyncWriteStream, ConstBufferSequence, ConstBufferIterator,
         CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
+
+  template <typename AsyncWriteStream, typename ConstBufferSequence,
+      typename ConstBufferIterator, typename CompletionCondition,
+      typename WriteHandler>
+  inline void start_write_buffer_sequence_op(AsyncWriteStream& stream,
+      const ConstBufferSequence& buffers, const ConstBufferIterator&,
+      CompletionCondition completion_condition, WriteHandler& handler)
+  {
+    detail::write_op<AsyncWriteStream, ConstBufferSequence,
+      ConstBufferIterator, CompletionCondition, WriteHandler>(
+        stream, buffers, completion_condition, handler)(
+          boost::system::error_code(), 0, 1);
+  }
+
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncWriteStream, typename ConstBufferSequence,
+    typename ConstBufferIterator, typename CompletionCondition,
+    typename WriteHandler, typename Allocator>
+struct associated_allocator<
+    detail::write_op<AsyncWriteStream, ConstBufferSequence,
+      ConstBufferIterator, CompletionCondition, WriteHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<WriteHandler, Allocator>::type type;
+
+  static type get(
+      const detail::write_op<AsyncWriteStream, ConstBufferSequence,
+        ConstBufferIterator, CompletionCondition, WriteHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<WriteHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncWriteStream, typename ConstBufferSequence,
+    typename ConstBufferIterator, typename CompletionCondition,
+    typename WriteHandler, typename Executor>
+struct associated_executor<
+    detail::write_op<AsyncWriteStream, ConstBufferSequence,
+      ConstBufferIterator, CompletionCondition, WriteHandler>,
+    Executor>
+{
+  typedef typename associated_executor<WriteHandler, Executor>::type type;
+
+  static type get(
+      const detail::write_op<AsyncWriteStream, ConstBufferSequence,
+        ConstBufferIterator, CompletionCondition, WriteHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<WriteHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename AsyncWriteStream, typename ConstBufferSequence,
   typename CompletionCondition, typename WriteHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
     void (boost::system::error_code, std::size_t))
 async_write(AsyncWriteStream& s, const ConstBufferSequence& buffers,
     CompletionCondition completion_condition,
-    BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type*)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::write_op<AsyncWriteStream, ConstBufferSequence,
-    CompletionCondition, BOOST_ASIO_HANDLER_TYPE(
-      WriteHandler, void (boost::system::error_code, std::size_t))>(
-        s, buffers, completion_condition, init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_write_buffer_sequence_op(s, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition,
+      init.completion_handler);
 
   return init.result.get();
 }
@@ -608,132 +420,227 @@ template <typename AsyncWriteStream, typename ConstBufferSequence,
 inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
     void (boost::system::error_code, std::size_t))
 async_write(AsyncWriteStream& s, const ConstBufferSequence& buffers,
-    BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type*)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::write_op<AsyncWriteStream, ConstBufferSequence,
-    detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(
-      WriteHandler, void (boost::system::error_code, std::size_t))>(
-        s, buffers, transfer_all(), init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_write_buffer_sequence_op(s, buffers,
+      boost::asio::buffer_sequence_begin(buffers), transfer_all(),
+      init.completion_handler);
 
   return init.result.get();
 }
 
-#if !defined(BOOST_ASIO_NO_IOSTREAM)
-
 namespace detail
 {
-  template <typename Allocator, typename WriteHandler>
-  class write_streambuf_handler
+  template <typename AsyncWriteStream, typename DynamicBuffer,
+      typename CompletionCondition, typename WriteHandler>
+  class write_dynbuf_op
   {
   public:
-    write_streambuf_handler(boost::asio::basic_streambuf<Allocator>& streambuf,
-        WriteHandler& handler)
-      : streambuf_(streambuf),
+    template <typename BufferSequence>
+    write_dynbuf_op(AsyncWriteStream& stream,
+        BOOST_ASIO_MOVE_ARG(BufferSequence) buffers,
+        CompletionCondition completion_condition, WriteHandler& handler)
+      : stream_(stream),
+        buffers_(BOOST_ASIO_MOVE_CAST(BufferSequence)(buffers)),
+        completion_condition_(
+          BOOST_ASIO_MOVE_CAST(CompletionCondition)(completion_condition)),
         handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
     {
     }
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    write_streambuf_handler(const write_streambuf_handler& other)
-      : streambuf_(other.streambuf_),
+    write_dynbuf_op(const write_dynbuf_op& other)
+      : stream_(other.stream_),
+        buffers_(other.buffers_),
+        completion_condition_(other.completion_condition_),
         handler_(other.handler_)
     {
     }
 
-    write_streambuf_handler(write_streambuf_handler&& other)
-      : streambuf_(other.streambuf_),
+    write_dynbuf_op(write_dynbuf_op&& other)
+      : stream_(other.stream_),
+        buffers_(BOOST_ASIO_MOVE_CAST(DynamicBuffer)(other.buffers_)),
+        completion_condition_(
+          BOOST_ASIO_MOVE_CAST(CompletionCondition)(
+            other.completion_condition_)),
         handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
     {
     }
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     void operator()(const boost::system::error_code& ec,
-        const std::size_t bytes_transferred)
+        std::size_t bytes_transferred, int start = 0)
     {
-      streambuf_.consume(bytes_transferred);
-      handler_(ec, bytes_transferred);
+      switch (start)
+      {
+        case 1:
+        async_write(stream_, buffers_.data(), completion_condition_,
+            BOOST_ASIO_MOVE_CAST(write_dynbuf_op)(*this));
+        return; default:
+        buffers_.consume(bytes_transferred);
+        handler_(ec, static_cast<const std::size_t&>(bytes_transferred));
+      }
     }
 
   //private:
-    boost::asio::basic_streambuf<Allocator>& streambuf_;
+    AsyncWriteStream& stream_;
+    DynamicBuffer buffers_;
+    CompletionCondition completion_condition_;
     WriteHandler handler_;
   };
 
-  template <typename Allocator, typename WriteHandler>
+  template <typename AsyncWriteStream, typename DynamicBuffer,
+      typename CompletionCondition, typename WriteHandler>
   inline void* asio_handler_allocate(std::size_t size,
-      write_streambuf_handler<Allocator, WriteHandler>* this_handler)
+      write_dynbuf_op<AsyncWriteStream, DynamicBuffer,
+        CompletionCondition, WriteHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename Allocator, typename WriteHandler>
+  template <typename AsyncWriteStream, typename DynamicBuffer,
+      typename CompletionCondition, typename WriteHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
-      write_streambuf_handler<Allocator, WriteHandler>* this_handler)
+      write_dynbuf_op<AsyncWriteStream, DynamicBuffer,
+        CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename Allocator, typename WriteHandler>
+  template <typename AsyncWriteStream, typename DynamicBuffer,
+      typename CompletionCondition, typename WriteHandler>
   inline bool asio_handler_is_continuation(
-      write_streambuf_handler<Allocator, WriteHandler>* this_handler)
+      write_dynbuf_op<AsyncWriteStream, DynamicBuffer,
+        CompletionCondition, WriteHandler>* this_handler)
   {
     return boost_asio_handler_cont_helpers::is_continuation(
         this_handler->handler_);
   }
 
-  template <typename Function, typename Allocator, typename WriteHandler>
+  template <typename Function, typename AsyncWriteStream,
+      typename DynamicBuffer, typename CompletionCondition,
+      typename WriteHandler>
   inline void asio_handler_invoke(Function& function,
-      write_streambuf_handler<Allocator, WriteHandler>* this_handler)
+      write_dynbuf_op<AsyncWriteStream, DynamicBuffer,
+        CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
-  template <typename Function, typename Allocator, typename WriteHandler>
+  template <typename Function, typename AsyncWriteStream,
+      typename DynamicBuffer, typename CompletionCondition,
+      typename WriteHandler>
   inline void asio_handler_invoke(const Function& function,
-      write_streambuf_handler<Allocator, WriteHandler>* this_handler)
+      write_dynbuf_op<AsyncWriteStream, DynamicBuffer,
+        CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 } // namespace detail
 
-template <typename AsyncWriteStream, typename Allocator,
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncWriteStream, typename DynamicBuffer,
+    typename CompletionCondition, typename WriteHandler, typename Allocator>
+struct associated_allocator<
+    detail::write_dynbuf_op<AsyncWriteStream,
+      DynamicBuffer, CompletionCondition, WriteHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<WriteHandler, Allocator>::type type;
+
+  static type get(
+      const detail::write_dynbuf_op<AsyncWriteStream,
+        DynamicBuffer, CompletionCondition, WriteHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<WriteHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncWriteStream, typename DynamicBuffer,
+    typename CompletionCondition, typename WriteHandler, typename Executor>
+struct associated_executor<
+    detail::write_dynbuf_op<AsyncWriteStream,
+      DynamicBuffer, CompletionCondition, WriteHandler>,
+    Executor>
+{
+  typedef typename associated_executor<WriteHandler, Executor>::type type;
+
+  static type get(
+      const detail::write_dynbuf_op<AsyncWriteStream,
+        DynamicBuffer, CompletionCondition, WriteHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<WriteHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncWriteStream,
+    typename DynamicBuffer, typename WriteHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+    void (boost::system::error_code, std::size_t))
+async_write(AsyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
+{
+  return async_write(s,
+      BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+      transfer_all(), BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+}
+
+template <typename AsyncWriteStream, typename DynamicBuffer,
     typename CompletionCondition, typename WriteHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
     void (boost::system::error_code, std::size_t))
 async_write(AsyncWriteStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
     CompletionCondition completion_condition,
-    BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type*)
 {
   // If you get an error on the following line it means that your handler does
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  async_write(s, b.data(), completion_condition,
-    detail::write_streambuf_handler<Allocator, BOOST_ASIO_HANDLER_TYPE(
-      WriteHandler, void (boost::system::error_code, std::size_t))>(
-        b, init.handler));
+  detail::write_dynbuf_op<AsyncWriteStream,
+    typename decay<DynamicBuffer>::type,
+      CompletionCondition, BOOST_ASIO_HANDLER_TYPE(
+        WriteHandler, void (boost::system::error_code, std::size_t))>(
+          s, BOOST_ASIO_MOVE_CAST(DynamicBuffer)(buffers),
+            completion_condition, init.completion_handler)(
+              boost::system::error_code(), 0, 1);
 
   return init.result.get();
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
 template <typename AsyncWriteStream, typename Allocator, typename WriteHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
     void (boost::system::error_code, std::size_t))
@@ -741,23 +648,25 @@ async_write(AsyncWriteStream& s,
     boost::asio::basic_streambuf<Allocator>& b,
     BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
 {
-  // If you get an error on the following line it means that your handler does
-  // not meet the documented type requirements for a WriteHandler.
-  BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
-
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
+  return async_write(s, basic_streambuf_ref<Allocator>(b),
       BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+}
 
-  async_write(s, b.data(), transfer_all(),
-    detail::write_streambuf_handler<Allocator, BOOST_ASIO_HANDLER_TYPE(
-      WriteHandler, void (boost::system::error_code, std::size_t))>(
-        b, init.handler));
-
-  return init.result.get();
+template <typename AsyncWriteStream, typename Allocator,
+    typename CompletionCondition, typename WriteHandler>
+inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+    void (boost::system::error_code, std::size_t))
+async_write(AsyncWriteStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    CompletionCondition completion_condition,
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+{
+  return async_write(s, basic_streambuf_ref<Allocator>(b),
+      completion_condition, BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/impl/write_at.hpp b/include/boost/asio/impl/write_at.hpp
index 20e95d9338..b1cf426c5e 100644
--- a/include/boost/asio/impl/write_at.hpp
+++ b/include/boost/asio/impl/write_at.hpp
@@ -15,6 +15,8 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/completion_condition.hpp>
 #include <boost/asio/detail/array_fwd.hpp>
@@ -33,28 +35,41 @@
 namespace boost {
 namespace asio {
 
+namespace detail
+{
+  template <typename SyncRandomAccessWriteDevice, typename ConstBufferSequence,
+      typename ConstBufferIterator, typename CompletionCondition>
+  std::size_t write_at_buffer_sequence(SyncRandomAccessWriteDevice& d,
+      uint64_t offset, const ConstBufferSequence& buffers,
+      const ConstBufferIterator&, CompletionCondition completion_condition,
+      boost::system::error_code& ec)
+  {
+    ec = boost::system::error_code();
+    boost::asio::detail::consuming_buffers<const_buffer,
+        ConstBufferSequence, ConstBufferIterator> tmp(buffers);
+    while (!tmp.empty())
+    {
+      if (std::size_t max_size = detail::adapt_completion_condition_result(
+            completion_condition(ec, tmp.total_consumed())))
+      {
+        tmp.consume(d.write_some_at(offset + tmp.total_consumed(),
+              tmp.prepare(max_size), ec));
+      }
+      else
+        break;
+    }
+    return tmp.total_consumed();;
+  }
+} // namespace detail
+
 template <typename SyncRandomAccessWriteDevice, typename ConstBufferSequence,
     typename CompletionCondition>
 std::size_t write_at(SyncRandomAccessWriteDevice& d,
     uint64_t offset, const ConstBufferSequence& buffers,
     CompletionCondition completion_condition, boost::system::error_code& ec)
 {
-  ec = boost::system::error_code();
-  boost::asio::detail::consuming_buffers<
-    const_buffer, ConstBufferSequence> tmp(buffers);
-  std::size_t total_transferred = 0;
-  tmp.prepare(detail::adapt_completion_condition_result(
-        completion_condition(ec, total_transferred)));
-  while (tmp.begin() != tmp.end())
-  {
-    std::size_t bytes_transferred = d.write_some_at(
-        offset + total_transferred, tmp, ec);
-    tmp.consume(bytes_transferred);
-    total_transferred += bytes_transferred;
-    tmp.prepare(detail::adapt_completion_condition_result(
-          completion_condition(ec, total_transferred)));
-  }
-  return total_transferred;
+  return detail::write_at_buffer_sequence(d, offset, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition, ec);
 }
 
 template <typename SyncRandomAccessWriteDevice, typename ConstBufferSequence>
@@ -89,6 +104,7 @@ inline std::size_t write_at(SyncRandomAccessWriteDevice& d,
   return bytes_transferred;
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 template <typename SyncRandomAccessWriteDevice, typename Allocator,
@@ -135,10 +151,12 @@ inline std::size_t write_at(SyncRandomAccessWriteDevice& d,
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 namespace detail
 {
-  template <typename AsyncRandomAccessWriteDevice, typename ConstBufferSequence,
+  template <typename AsyncRandomAccessWriteDevice,
+      typename ConstBufferSequence, typename ConstBufferIterator,
       typename CompletionCondition, typename WriteHandler>
   class write_at_op
     : detail::base_from_completion_cond<CompletionCondition>
@@ -153,7 +171,6 @@ namespace detail
         offset_(offset),
         buffers_(buffers),
         start_(0),
-        total_transferred_(0),
         handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
     {
     }
@@ -165,7 +182,6 @@ namespace detail
         offset_(other.offset_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(other.handler_)
     {
     }
@@ -176,7 +192,6 @@ namespace detail
         offset_(other.offset_),
         buffers_(other.buffers_),
         start_(other.start_),
-        total_transferred_(other.total_transferred_),
         handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
     {
     }
@@ -185,405 +200,64 @@ namespace detail
     void operator()(const boost::system::error_code& ec,
         std::size_t bytes_transferred, int start = 0)
     {
+      std::size_t max_size;
       switch (start_ = start)
       {
         case 1:
-        buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-        for (;;)
+        max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        do
         {
           device_.async_write_some_at(
-              offset_ + total_transferred_, buffers_,
+              offset_ + buffers_.total_consumed(), buffers_.prepare(max_size),
               BOOST_ASIO_MOVE_CAST(write_at_op)(*this));
           return; default:
-          total_transferred_ += bytes_transferred;
           buffers_.consume(bytes_transferred);
-          buffers_.prepare(this->check_for_completion(ec, total_transferred_));
-          if ((!ec && bytes_transferred == 0)
-              || buffers_.begin() == buffers_.end())
+          if ((!ec && bytes_transferred == 0) || buffers_.empty())
             break;
-        }
+          max_size = this->check_for_completion(ec, buffers_.total_consumed());
+        } while (max_size > 0);
 
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
+        handler_(ec, buffers_.total_consumed());
       }
     }
 
   //private:
     AsyncRandomAccessWriteDevice& device_;
     uint64_t offset_;
-    boost::asio::detail::consuming_buffers<
-      const_buffer, ConstBufferSequence> buffers_;
+    boost::asio::detail::consuming_buffers<const_buffer,
+        ConstBufferSequence, ConstBufferIterator> buffers_;
     int start_;
-    std::size_t total_transferred_;
     WriteHandler handler_;
   };
 
   template <typename AsyncRandomAccessWriteDevice,
-      typename CompletionCondition, typename WriteHandler>
-  class write_at_op<AsyncRandomAccessWriteDevice,
-      boost::asio::mutable_buffers_1, CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_at_op(AsyncRandomAccessWriteDevice& device,
-        uint64_t offset, const boost::asio::mutable_buffers_1& buffers,
-        CompletionCondition completion_condition,
-        WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        device_(device),
-        offset_(offset),
-        buffer_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_at_op(const write_at_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_at_op(write_at_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          device_.async_write_some_at(offset_ + total_transferred_,
-              boost::asio::buffer(buffer_ + total_transferred_, n),
-              BOOST_ASIO_MOVE_CAST(write_at_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == boost::asio::buffer_size(buffer_))
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncRandomAccessWriteDevice& device_;
-    uint64_t offset_;
-    boost::asio::mutable_buffer buffer_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-  template <typename AsyncRandomAccessWriteDevice,
-      typename CompletionCondition, typename WriteHandler>
-  class write_at_op<AsyncRandomAccessWriteDevice, boost::asio::const_buffers_1,
-      CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_at_op(AsyncRandomAccessWriteDevice& device,
-        uint64_t offset, const boost::asio::const_buffers_1& buffers,
-        CompletionCondition completion_condition,
-        WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        device_(device),
-        offset_(offset),
-        buffer_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_at_op(const write_at_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_at_op(write_at_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffer_(other.buffer_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          device_.async_write_some_at(offset_ + total_transferred_,
-              boost::asio::buffer(buffer_ + total_transferred_, n),
-              BOOST_ASIO_MOVE_CAST(write_at_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == boost::asio::buffer_size(buffer_))
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncRandomAccessWriteDevice& device_;
-    uint64_t offset_;
-    boost::asio::const_buffer buffer_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-  template <typename AsyncRandomAccessWriteDevice, typename Elem,
-      typename CompletionCondition, typename WriteHandler>
-  class write_at_op<AsyncRandomAccessWriteDevice, boost::array<Elem, 2>,
-      CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_at_op(AsyncRandomAccessWriteDevice& device,
-        uint64_t offset, const boost::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        device_(device),
-        offset_(offset),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_at_op(const write_at_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_at_op(write_at_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          boost::array<boost::asio::const_buffer, 2> >::type bufs = {{
-        boost::asio::const_buffer(buffers_[0]),
-        boost::asio::const_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          device_.async_write_some_at(offset_ + total_transferred_,
-              bufs, BOOST_ASIO_MOVE_CAST(write_at_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncRandomAccessWriteDevice& device_;
-    uint64_t offset_;
-    boost::array<Elem, 2> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-#if defined(BOOST_ASIO_HAS_STD_ARRAY)
-
-  template <typename AsyncRandomAccessWriteDevice, typename Elem,
-      typename CompletionCondition, typename WriteHandler>
-  class write_at_op<AsyncRandomAccessWriteDevice, std::array<Elem, 2>,
-      CompletionCondition, WriteHandler>
-    : detail::base_from_completion_cond<CompletionCondition>
-  {
-  public:
-    write_at_op(AsyncRandomAccessWriteDevice& device,
-        uint64_t offset, const std::array<Elem, 2>& buffers,
-        CompletionCondition completion_condition, WriteHandler& handler)
-      : detail::base_from_completion_cond<
-          CompletionCondition>(completion_condition),
-        device_(device),
-        offset_(offset),
-        buffers_(buffers),
-        start_(0),
-        total_transferred_(0),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(handler))
-    {
-    }
-
-#if defined(BOOST_ASIO_HAS_MOVE)
-    write_at_op(const write_at_op& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(other.handler_)
-    {
-    }
-
-    write_at_op(write_at_op&& other)
-      : detail::base_from_completion_cond<CompletionCondition>(other),
-        device_(other.device_),
-        offset_(other.offset_),
-        buffers_(other.buffers_),
-        start_(other.start_),
-        total_transferred_(other.total_transferred_),
-        handler_(BOOST_ASIO_MOVE_CAST(WriteHandler)(other.handler_))
-    {
-    }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
-
-    void operator()(const boost::system::error_code& ec,
-        std::size_t bytes_transferred, int start = 0)
-    {
-      typename boost::asio::detail::dependent_type<Elem,
-          std::array<boost::asio::const_buffer, 2> >::type bufs = {{
-        boost::asio::const_buffer(buffers_[0]),
-        boost::asio::const_buffer(buffers_[1]) }};
-      std::size_t buffer_size0 = boost::asio::buffer_size(bufs[0]);
-      std::size_t buffer_size1 = boost::asio::buffer_size(bufs[1]);
-      std::size_t n = 0;
-      switch (start_ = start)
-      {
-        case 1:
-        n = this->check_for_completion(ec, total_transferred_);
-        for (;;)
-        {
-          bufs[0] = boost::asio::buffer(bufs[0] + total_transferred_, n);
-          bufs[1] = boost::asio::buffer(
-              bufs[1] + (total_transferred_ < buffer_size0
-                ? 0 : total_transferred_ - buffer_size0),
-              n - boost::asio::buffer_size(bufs[0]));
-          device_.async_write_some_at(offset_ + total_transferred_,
-              bufs, BOOST_ASIO_MOVE_CAST(write_at_op)(*this));
-          return; default:
-          total_transferred_ += bytes_transferred;
-          if ((!ec && bytes_transferred == 0)
-              || (n = this->check_for_completion(ec, total_transferred_)) == 0
-              || total_transferred_ == buffer_size0 + buffer_size1)
-            break;
-        }
-
-        handler_(ec, static_cast<const std::size_t&>(total_transferred_));
-      }
-    }
-
-  //private:
-    AsyncRandomAccessWriteDevice& device_;
-    uint64_t offset_;
-    std::array<Elem, 2> buffers_;
-    int start_;
-    std::size_t total_transferred_;
-    WriteHandler handler_;
-  };
-
-#endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
-
-  template <typename AsyncRandomAccessWriteDevice, typename ConstBufferSequence,
+      typename ConstBufferSequence, typename ConstBufferIterator,
       typename CompletionCondition, typename WriteHandler>
   inline void* asio_handler_allocate(std::size_t size,
       write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
-        CompletionCondition, WriteHandler>* this_handler)
+        ConstBufferIterator, CompletionCondition, WriteHandler>* this_handler)
   {
     return boost_asio_handler_alloc_helpers::allocate(
         size, this_handler->handler_);
   }
 
-  template <typename AsyncRandomAccessWriteDevice, typename ConstBufferSequence,
+  template <typename AsyncRandomAccessWriteDevice,
+      typename ConstBufferSequence, typename ConstBufferIterator,
       typename CompletionCondition, typename WriteHandler>
   inline void asio_handler_deallocate(void* pointer, std::size_t size,
       write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
-        CompletionCondition, WriteHandler>* this_handler)
+        ConstBufferIterator, CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_alloc_helpers::deallocate(
         pointer, size, this_handler->handler_);
   }
 
-  template <typename AsyncRandomAccessWriteDevice, typename ConstBufferSequence,
+  template <typename AsyncRandomAccessWriteDevice,
+      typename ConstBufferSequence, typename ConstBufferIterator,
       typename CompletionCondition, typename WriteHandler>
   inline bool asio_handler_is_continuation(
       write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
-        CompletionCondition, WriteHandler>* this_handler)
+        ConstBufferIterator, CompletionCondition, WriteHandler>* this_handler)
   {
     return this_handler->start_ == 0 ? true
       : boost_asio_handler_cont_helpers::is_continuation(
@@ -591,41 +265,86 @@ namespace detail
   }
 
   template <typename Function, typename AsyncRandomAccessWriteDevice,
-      typename ConstBufferSequence, typename CompletionCondition,
-      typename WriteHandler>
+      typename ConstBufferSequence, typename ConstBufferIterator,
+      typename CompletionCondition, typename WriteHandler>
   inline void asio_handler_invoke(Function& function,
       write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
-        CompletionCondition, WriteHandler>* this_handler)
+        ConstBufferIterator, CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
   template <typename Function, typename AsyncRandomAccessWriteDevice,
-      typename ConstBufferSequence, typename CompletionCondition,
-      typename WriteHandler>
+      typename ConstBufferSequence, typename ConstBufferIterator,
+      typename CompletionCondition, typename WriteHandler>
   inline void asio_handler_invoke(const Function& function,
       write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
-        CompletionCondition, WriteHandler>* this_handler)
+        ConstBufferIterator, CompletionCondition, WriteHandler>* this_handler)
   {
     boost_asio_handler_invoke_helpers::invoke(
         function, this_handler->handler_);
   }
 
-  template <typename AsyncRandomAccessWriteDevice, typename ConstBufferSequence,
+  template <typename AsyncRandomAccessWriteDevice,
+      typename ConstBufferSequence, typename ConstBufferIterator,
       typename CompletionCondition, typename WriteHandler>
-  inline write_at_op<AsyncRandomAccessWriteDevice,
-      ConstBufferSequence, CompletionCondition, WriteHandler>
-  make_write_at_op(AsyncRandomAccessWriteDevice& d,
+  inline void start_write_at_buffer_sequence_op(AsyncRandomAccessWriteDevice& d,
       uint64_t offset, const ConstBufferSequence& buffers,
-      CompletionCondition completion_condition, WriteHandler handler)
+      const ConstBufferIterator&, CompletionCondition completion_condition,
+      WriteHandler& handler)
   {
-    return write_at_op<AsyncRandomAccessWriteDevice,
-      ConstBufferSequence, CompletionCondition, WriteHandler>(
-        d, offset, buffers, completion_condition, handler);
+    detail::write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
+      ConstBufferIterator, CompletionCondition, WriteHandler>(
+        d, offset, buffers, completion_condition, handler)(
+          boost::system::error_code(), 0, 1);
   }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename AsyncRandomAccessWriteDevice,
+    typename ConstBufferSequence, typename ConstBufferIterator,
+    typename CompletionCondition, typename WriteHandler, typename Allocator>
+struct associated_allocator<
+    detail::write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
+      ConstBufferIterator, CompletionCondition, WriteHandler>,
+    Allocator>
+{
+  typedef typename associated_allocator<WriteHandler, Allocator>::type type;
+
+  static type get(
+      const detail::write_at_op<AsyncRandomAccessWriteDevice,
+        ConstBufferSequence, ConstBufferIterator,
+        CompletionCondition, WriteHandler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<WriteHandler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename AsyncRandomAccessWriteDevice,
+    typename ConstBufferSequence, typename ConstBufferIterator,
+    typename CompletionCondition, typename WriteHandler, typename Executor>
+struct associated_executor<
+    detail::write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
+      ConstBufferIterator, CompletionCondition, WriteHandler>,
+    Executor>
+{
+  typedef typename associated_executor<WriteHandler, Executor>::type type;
+
+  static type get(
+      const detail::write_at_op<AsyncRandomAccessWriteDevice,
+        ConstBufferSequence, ConstBufferIterator,
+        CompletionCondition, WriteHandler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<WriteHandler, Executor>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename AsyncRandomAccessWriteDevice, typename ConstBufferSequence,
     typename CompletionCondition, typename WriteHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
@@ -639,15 +358,12 @@ async_write_at(AsyncRandomAccessWriteDevice& d,
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
-    CompletionCondition, BOOST_ASIO_HANDLER_TYPE(
-      WriteHandler, void (boost::system::error_code, std::size_t))>(
-        d, offset, buffers, completion_condition, init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_write_at_buffer_sequence_op(d, offset, buffers,
+      boost::asio::buffer_sequence_begin(buffers), completion_condition,
+      init.completion_handler);
 
   return init.result.get();
 }
@@ -664,19 +380,17 @@ async_write_at(AsyncRandomAccessWriteDevice& d,
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
-  detail::write_at_op<AsyncRandomAccessWriteDevice, ConstBufferSequence,
-    detail::transfer_all_t, BOOST_ASIO_HANDLER_TYPE(
-      WriteHandler, void (boost::system::error_code, std::size_t))>(
-        d, offset, buffers, transfer_all(), init.handler)(
-          boost::system::error_code(), 0, 1);
+  detail::start_write_at_buffer_sequence_op(d, offset, buffers,
+      boost::asio::buffer_sequence_begin(buffers), transfer_all(),
+      init.completion_handler);
 
   return init.result.get();
 }
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 namespace detail
@@ -768,6 +482,40 @@ namespace detail
   }
 } // namespace detail
 
+#if !defined(GENERATING_DOCUMENTATION)
+
+template <typename Allocator, typename WriteHandler, typename Allocator1>
+struct associated_allocator<
+    detail::write_at_streambuf_op<Allocator, WriteHandler>,
+    Allocator1>
+{
+  typedef typename associated_allocator<WriteHandler, Allocator1>::type type;
+
+  static type get(
+      const detail::write_at_streambuf_op<Allocator, WriteHandler>& h,
+      const Allocator1& a = Allocator1()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<WriteHandler, Allocator1>::get(h.handler_, a);
+  }
+};
+
+template <typename Executor, typename WriteHandler, typename Executor1>
+struct associated_executor<
+    detail::write_at_streambuf_op<Executor, WriteHandler>,
+    Executor1>
+{
+  typedef typename associated_executor<WriteHandler, Executor1>::type type;
+
+  static type get(
+      const detail::write_at_streambuf_op<Executor, WriteHandler>& h,
+      const Executor1& ex = Executor1()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<WriteHandler, Executor1>::get(h.handler_, ex);
+  }
+};
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
 template <typename AsyncRandomAccessWriteDevice, typename Allocator,
     typename CompletionCondition, typename WriteHandler>
 inline BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
@@ -781,14 +529,13 @@ async_write_at(AsyncRandomAccessWriteDevice& d,
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   async_write_at(d, offset, b.data(), completion_condition,
     detail::write_at_streambuf_op<Allocator, BOOST_ASIO_HANDLER_TYPE(
       WriteHandler, void (boost::system::error_code, std::size_t))>(
-        b, init.handler));
+        b, init.completion_handler));
 
   return init.result.get();
 }
@@ -805,19 +552,19 @@ async_write_at(AsyncRandomAccessWriteDevice& d,
   // not meet the documented type requirements for a WriteHandler.
   BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-  detail::async_result_init<
-    WriteHandler, void (boost::system::error_code, std::size_t)> init(
-      BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+  async_completion<WriteHandler,
+    void (boost::system::error_code, std::size_t)> init(handler);
 
   async_write_at(d, offset, b.data(), transfer_all(),
     detail::write_at_streambuf_op<Allocator, BOOST_ASIO_HANDLER_TYPE(
       WriteHandler, void (boost::system::error_code, std::size_t))>(
-        b, init.handler));
+        b, init.completion_handler));
 
   return init.result.get();
 }
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/io_context.hpp b/include/boost/asio/io_context.hpp
new file mode 100644
index 0000000000..ac1701d122
--- /dev/null
+++ b/include/boost/asio/io_context.hpp
@@ -0,0 +1,849 @@
+//
+// io_context.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IO_CONTEXT_HPP
+#define BOOST_ASIO_IO_CONTEXT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <cstddef>
+#include <stdexcept>
+#include <typeinfo>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/wrapped_handler.hpp>
+#include <boost/system/error_code.hpp>
+#include <boost/asio/execution_context.hpp>
+
+#if defined(BOOST_ASIO_HAS_CHRONO)
+# include <boost/asio/detail/chrono.hpp>
+#endif // defined(BOOST_ASIO_HAS_CHRONO)
+
+#if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
+# include <boost/asio/detail/winsock_init.hpp>
+#elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
+  || defined(__osf__)
+# include <boost/asio/detail/signal_init.hpp>
+#endif
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+namespace detail {
+#if defined(BOOST_ASIO_HAS_IOCP)
+  typedef class win_iocp_io_context io_context_impl;
+  class win_iocp_overlapped_ptr;
+#else
+  typedef class scheduler io_context_impl;
+#endif
+} // namespace detail
+
+/// Provides core I/O functionality.
+/**
+ * The io_context class provides the core I/O functionality for users of the
+ * asynchronous I/O objects, including:
+ *
+ * @li boost::asio::ip::tcp::socket
+ * @li boost::asio::ip::tcp::acceptor
+ * @li boost::asio::ip::udp::socket
+ * @li boost::asio::deadline_timer.
+ *
+ * The io_context class also includes facilities intended for developers of
+ * custom asynchronous services.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Safe, with the specific exceptions of the restart()
+ * and notify_fork() functions. Calling restart() while there are unfinished
+ * run(), run_one(), run_for(), run_until(), poll() or poll_one() calls results
+ * in undefined behaviour. The notify_fork() function should not be called
+ * while any io_context function, or any function on an I/O object that is
+ * associated with the io_context, is being called in another thread.
+ *
+ * @par Concepts:
+ * Dispatcher.
+ *
+ * @par Synchronous and asynchronous operations
+ *
+ * Synchronous operations on I/O objects implicitly run the io_context object
+ * for an individual operation. The io_context functions run(), run_one(),
+ * run_for(), run_until(), poll() or poll_one() must be called for the
+ * io_context to perform asynchronous operations on behalf of a C++ program.
+ * Notification that an asynchronous operation has completed is delivered by
+ * invocation of the associated handler. Handlers are invoked only by a thread
+ * that is currently calling any overload of run(), run_one(), run_for(),
+ * run_until(), poll() or poll_one() for the io_context.
+ *
+ * @par Effect of exceptions thrown from handlers
+ *
+ * If an exception is thrown from a handler, the exception is allowed to
+ * propagate through the throwing thread's invocation of run(), run_one(),
+ * run_for(), run_until(), poll() or poll_one(). No other threads that are
+ * calling any of these functions are affected. It is then the responsibility
+ * of the application to catch the exception.
+ *
+ * After the exception has been caught, the run(), run_one(), run_for(),
+ * run_until(), poll() or poll_one() call may be restarted @em without the need
+ * for an intervening call to restart(). This allows the thread to rejoin the
+ * io_context object's thread pool without impacting any other threads in the
+ * pool.
+ *
+ * For example:
+ *
+ * @code
+ * boost::asio::io_context io_context;
+ * ...
+ * for (;;)
+ * {
+ *   try
+ *   {
+ *     io_context.run();
+ *     break; // run() exited normally
+ *   }
+ *   catch (my_exception& e)
+ *   {
+ *     // Deal with exception as appropriate.
+ *   }
+ * }
+ * @endcode
+ *
+ * @par Stopping the io_context from running out of work
+ *
+ * Some applications may need to prevent an io_context object's run() call from
+ * returning when there is no more work to do. For example, the io_context may
+ * be being run in a background thread that is launched prior to the
+ * application's asynchronous operations. The run() call may be kept running by
+ * creating an object of type
+ * boost::asio::executor_work_guard<io_context::executor_type>:
+ *
+ * @code boost::asio::io_context io_context;
+ * boost::asio::executor_work_guard<boost::asio::io_context::executor_type>
+ *   = boost::asio::make_work_guard(io_context);
+ * ... @endcode
+ *
+ * To effect a shutdown, the application will then need to call the io_context
+ * object's stop() member function. This will cause the io_context run() call
+ * to return as soon as possible, abandoning unfinished operations and without
+ * permitting ready handlers to be dispatched.
+ *
+ * Alternatively, if the application requires that all operations and handlers
+ * be allowed to finish normally, the work object may be explicitly reset.
+ *
+ * @code boost::asio::io_context io_context;
+ * boost::asio::executor_work_guard<boost::asio::io_context::executor_type>
+ *   = boost::asio::make_work_guard(io_context);
+ * ...
+ * work.reset(); // Allow run() to exit. @endcode
+ */
+class io_context
+  : public execution_context
+{
+private:
+  typedef detail::io_context_impl impl_type;
+#if defined(BOOST_ASIO_HAS_IOCP)
+  friend class detail::win_iocp_overlapped_ptr;
+#endif
+
+public:
+  class executor_type;
+  friend class executor_type;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  class work;
+  friend class work;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  class service;
+
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+  class strand;
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
+  /// The type used to count the number of handlers executed by the context.
+  typedef std::size_t count_type;
+
+  /// Constructor.
+  BOOST_ASIO_DECL io_context();
+
+  /// Constructor.
+  /**
+   * Construct with a hint about the required level of concurrency.
+   *
+   * @param concurrency_hint A suggestion to the implementation on how many
+   * threads it should allow to run simultaneously.
+   */
+  BOOST_ASIO_DECL explicit io_context(int concurrency_hint);
+
+  /// Destructor.
+  /**
+   * On destruction, the io_context performs the following sequence of
+   * operations:
+   *
+   * @li For each service object @c svc in the io_context set, in reverse order
+   * of the beginning of service object lifetime, performs
+   * @c svc->shutdown().
+   *
+   * @li Uninvoked handler objects that were scheduled for deferred invocation
+   * on the io_context, or any associated strand, are destroyed.
+   *
+   * @li For each service object @c svc in the io_context set, in reverse order
+   * of the beginning of service object lifetime, performs
+   * <tt>delete static_cast<io_context::service*>(svc)</tt>.
+   *
+   * @note The destruction sequence described above permits programs to
+   * simplify their resource management by using @c shared_ptr<>. Where an
+   * object's lifetime is tied to the lifetime of a connection (or some other
+   * sequence of asynchronous operations), a @c shared_ptr to the object would
+   * be bound into the handlers for all asynchronous operations associated with
+   * it. This works as follows:
+   *
+   * @li When a single connection ends, all associated asynchronous operations
+   * complete. The corresponding handler objects are destroyed, and all
+   * @c shared_ptr references to the objects are destroyed.
+   *
+   * @li To shut down the whole program, the io_context function stop() is
+   * called to terminate any run() calls as soon as possible. The io_context
+   * destructor defined above destroys all handlers, causing all @c shared_ptr
+   * references to all connection objects to be destroyed.
+   */
+  BOOST_ASIO_DECL ~io_context();
+
+  /// Obtains the executor associated with the io_context.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT;
+
+  /// Run the io_context object's event processing loop.
+  /**
+   * The run() function blocks until all work has finished and there are no
+   * more handlers to be dispatched, or until the io_context has been stopped.
+   *
+   * Multiple threads may call the run() function to set up a pool of threads
+   * from which the io_context may execute handlers. All threads that are
+   * waiting in the pool are equivalent and the io_context may choose any one
+   * of them to invoke a handler.
+   *
+   * A normal exit from the run() function implies that the io_context object
+   * is stopped (the stopped() function returns @c true). Subsequent calls to
+   * run(), run_one(), poll() or poll_one() will return immediately unless there
+   * is a prior call to restart().
+   *
+   * @return The number of handlers that were executed.
+   *
+   * @note Calling the run() function from a thread that is currently calling
+   * one of run(), run_one(), run_for(), run_until(), poll() or poll_one() on
+   * the same io_context object may introduce the potential for deadlock. It is
+   * the caller's reponsibility to avoid this.
+   *
+   * The poll() function may also be used to dispatch ready handlers, but
+   * without blocking.
+   */
+  BOOST_ASIO_DECL count_type run();
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use non-error_code overload.) Run the io_context object's
+  /// event processing loop.
+  /**
+   * The run() function blocks until all work has finished and there are no
+   * more handlers to be dispatched, or until the io_context has been stopped.
+   *
+   * Multiple threads may call the run() function to set up a pool of threads
+   * from which the io_context may execute handlers. All threads that are
+   * waiting in the pool are equivalent and the io_context may choose any one
+   * of them to invoke a handler.
+   *
+   * A normal exit from the run() function implies that the io_context object
+   * is stopped (the stopped() function returns @c true). Subsequent calls to
+   * run(), run_one(), poll() or poll_one() will return immediately unless there
+   * is a prior call to restart().
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @return The number of handlers that were executed.
+   *
+   * @note Calling the run() function from a thread that is currently calling
+   * one of run(), run_one(), run_for(), run_until(), poll() or poll_one() on
+   * the same io_context object may introduce the potential for deadlock. It is
+   * the caller's reponsibility to avoid this.
+   *
+   * The poll() function may also be used to dispatch ready handlers, but
+   * without blocking.
+   */
+  BOOST_ASIO_DECL count_type run(boost::system::error_code& ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+#if defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
+  /// Run the io_context object's event processing loop for a specified
+  /// duration.
+  /**
+   * The run_for() function blocks until all work has finished and there are no
+   * more handlers to be dispatched, until the io_context has been stopped, or
+   * until the specified duration has elapsed.
+   *
+   * @param rel_time The duration for which the call may block.
+   *
+   * @return The number of handlers that were executed.
+   */
+  template <typename Rep, typename Period>
+  std::size_t run_for(const chrono::duration<Rep, Period>& rel_time);
+
+  /// Run the io_context object's event processing loop until a specified time.
+  /**
+   * The run_until() function blocks until all work has finished and there are
+   * no more handlers to be dispatched, until the io_context has been stopped,
+   * or until the specified time has been reached.
+   *
+   * @param abs_time The time point until which the call may block.
+   *
+   * @return The number of handlers that were executed.
+   */
+  template <typename Clock, typename Duration>
+  std::size_t run_until(const chrono::time_point<Clock, Duration>& abs_time);
+#endif // defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
+
+  /// Run the io_context object's event processing loop to execute at most one
+  /// handler.
+  /**
+   * The run_one() function blocks until one handler has been dispatched, or
+   * until the io_context has been stopped.
+   *
+   * @return The number of handlers that were executed. A zero return value
+   * implies that the io_context object is stopped (the stopped() function
+   * returns @c true). Subsequent calls to run(), run_one(), poll() or
+   * poll_one() will return immediately unless there is a prior call to
+   * restart().
+   *
+   * @note Calling the run_one() function from a thread that is currently
+   * calling one of run(), run_one(), run_for(), run_until(), poll() or
+   * poll_one() on the same io_context object may introduce the potential for
+   * deadlock. It is the caller's reponsibility to avoid this.
+   */
+  BOOST_ASIO_DECL count_type run_one();
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use non-error_code overlaod.) Run the io_context object's
+  /// event processing loop to execute at most one handler.
+  /**
+   * The run_one() function blocks until one handler has been dispatched, or
+   * until the io_context has been stopped.
+   *
+   * @return The number of handlers that were executed. A zero return value
+   * implies that the io_context object is stopped (the stopped() function
+   * returns @c true). Subsequent calls to run(), run_one(), poll() or
+   * poll_one() will return immediately unless there is a prior call to
+   * restart().
+   *
+   * @return The number of handlers that were executed.
+   *
+   * @note Calling the run_one() function from a thread that is currently
+   * calling one of run(), run_one(), run_for(), run_until(), poll() or
+   * poll_one() on the same io_context object may introduce the potential for
+   * deadlock. It is the caller's reponsibility to avoid this.
+   */
+  BOOST_ASIO_DECL count_type run_one(boost::system::error_code& ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+#if defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
+  /// Run the io_context object's event processing loop for a specified duration
+  /// to execute at most one handler.
+  /**
+   * The run_one_for() function blocks until one handler has been dispatched,
+   * until the io_context has been stopped, or until the specified duration has
+   * elapsed.
+   *
+   * @param rel_time The duration for which the call may block.
+   *
+   * @return The number of handlers that were executed.
+   */
+  template <typename Rep, typename Period>
+  std::size_t run_one_for(const chrono::duration<Rep, Period>& rel_time);
+
+  /// Run the io_context object's event processing loop until a specified time
+  /// to execute at most one handler.
+  /**
+   * The run_one_until() function blocks until one handler has been dispatched,
+   * until the io_context has been stopped, or until the specified time has
+   * been reached.
+   *
+   * @param abs_time The time point until which the call may block.
+   *
+   * @return The number of handlers that were executed.
+   */
+  template <typename Clock, typename Duration>
+  std::size_t run_one_until(
+      const chrono::time_point<Clock, Duration>& abs_time);
+#endif // defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
+
+  /// Run the io_context object's event processing loop to execute ready
+  /// handlers.
+  /**
+   * The poll() function runs handlers that are ready to run, without blocking,
+   * until the io_context has been stopped or there are no more ready handlers.
+   *
+   * @return The number of handlers that were executed.
+   */
+  BOOST_ASIO_DECL count_type poll();
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use non-error_code overload.) Run the io_context object's
+  /// event processing loop to execute ready handlers.
+  /**
+   * The poll() function runs handlers that are ready to run, without blocking,
+   * until the io_context has been stopped or there are no more ready handlers.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @return The number of handlers that were executed.
+   */
+  BOOST_ASIO_DECL count_type poll(boost::system::error_code& ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Run the io_context object's event processing loop to execute one ready
+  /// handler.
+  /**
+   * The poll_one() function runs at most one handler that is ready to run,
+   * without blocking.
+   *
+   * @return The number of handlers that were executed.
+   */
+  BOOST_ASIO_DECL count_type poll_one();
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use non-error_code overload.) Run the io_context object's
+  /// event processing loop to execute one ready handler.
+  /**
+   * The poll_one() function runs at most one handler that is ready to run,
+   * without blocking.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @return The number of handlers that were executed.
+   */
+  BOOST_ASIO_DECL count_type poll_one(boost::system::error_code& ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Stop the io_context object's event processing loop.
+  /**
+   * This function does not block, but instead simply signals the io_context to
+   * stop. All invocations of its run() or run_one() member functions should
+   * return as soon as possible. Subsequent calls to run(), run_one(), poll()
+   * or poll_one() will return immediately until restart() is called.
+   */
+  BOOST_ASIO_DECL void stop();
+
+  /// Determine whether the io_context object has been stopped.
+  /**
+   * This function is used to determine whether an io_context object has been
+   * stopped, either through an explicit call to stop(), or due to running out
+   * of work. When an io_context object is stopped, calls to run(), run_one(),
+   * poll() or poll_one() will return immediately without invoking any
+   * handlers.
+   *
+   * @return @c true if the io_context object is stopped, otherwise @c false.
+   */
+  BOOST_ASIO_DECL bool stopped() const;
+
+  /// Restart the io_context in preparation for a subsequent run() invocation.
+  /**
+   * This function must be called prior to any second or later set of
+   * invocations of the run(), run_one(), poll() or poll_one() functions when a
+   * previous invocation of these functions returned due to the io_context
+   * being stopped or running out of work. After a call to restart(), the
+   * io_context object's stopped() function will return @c false.
+   *
+   * This function must not be called while there are any unfinished calls to
+   * the run(), run_one(), poll() or poll_one() functions.
+   */
+  BOOST_ASIO_DECL void restart();
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use restart().) Reset the io_context in preparation for a
+  /// subsequent run() invocation.
+  /**
+   * This function must be called prior to any second or later set of
+   * invocations of the run(), run_one(), poll() or poll_one() functions when a
+   * previous invocation of these functions returned due to the io_context
+   * being stopped or running out of work. After a call to restart(), the
+   * io_context object's stopped() function will return @c false.
+   *
+   * This function must not be called while there are any unfinished calls to
+   * the run(), run_one(), poll() or poll_one() functions.
+   */
+  void reset();
+
+  /// (Deprecated: Use boost::asio::dispatch().) Request the io_context to
+  /// invoke the given handler.
+  /**
+   * This function is used to ask the io_context to execute the given handler.
+   *
+   * The io_context guarantees that the handler will only be called in a thread
+   * in which the run(), run_one(), poll() or poll_one() member functions is
+   * currently being invoked. The handler may be executed inside this function
+   * if the guarantee can be met.
+   *
+   * @param handler The handler to be called. The io_context will make
+   * a copy of the handler object as required. The function signature of the
+   * handler must be: @code void handler(); @endcode
+   *
+   * @note This function throws an exception only if:
+   *
+   * @li the handler's @c asio_handler_allocate function; or
+   *
+   * @li the handler's copy constructor
+   *
+   * throws an exception.
+   */
+  template <typename CompletionHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
+  dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
+
+  /// (Deprecated: Use boost::asio::post().) Request the io_context to invoke
+  /// the given handler and return immediately.
+  /**
+   * This function is used to ask the io_context to execute the given handler,
+   * but without allowing the io_context to call the handler from inside this
+   * function.
+   *
+   * The io_context guarantees that the handler will only be called in a thread
+   * in which the run(), run_one(), poll() or poll_one() member functions is
+   * currently being invoked.
+   *
+   * @param handler The handler to be called. The io_context will make
+   * a copy of the handler object as required. The function signature of the
+   * handler must be: @code void handler(); @endcode
+   *
+   * @note This function throws an exception only if:
+   *
+   * @li the handler's @c asio_handler_allocate function; or
+   *
+   * @li the handler's copy constructor
+   *
+   * throws an exception.
+   */
+  template <typename CompletionHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
+  post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
+
+  /// (Deprecated: Use boost::asio::bind_executor().) Create a new handler that
+  /// automatically dispatches the wrapped handler on the io_context.
+  /**
+   * This function is used to create a new handler function object that, when
+   * invoked, will automatically pass the wrapped handler to the io_context
+   * object's dispatch function.
+   *
+   * @param handler The handler to be wrapped. The io_context will make a copy
+   * of the handler object as required. The function signature of the handler
+   * must be: @code void handler(A1 a1, ... An an); @endcode
+   *
+   * @return A function object that, when invoked, passes the wrapped handler to
+   * the io_context object's dispatch function. Given a function object with the
+   * signature:
+   * @code R f(A1 a1, ... An an); @endcode
+   * If this function object is passed to the wrap function like so:
+   * @code io_context.wrap(f); @endcode
+   * then the return value is a function object with the signature
+   * @code void g(A1 a1, ... An an); @endcode
+   * that, when invoked, executes code equivalent to:
+   * @code io_context.dispatch(boost::bind(f, a1, ... an)); @endcode
+   */
+  template <typename Handler>
+#if defined(GENERATING_DOCUMENTATION)
+  unspecified
+#else
+  detail::wrapped_handler<io_context&, Handler>
+#endif
+  wrap(Handler handler);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+private:
+  // Helper function to add the implementation.
+  BOOST_ASIO_DECL impl_type& add_impl(impl_type* impl);
+
+  // Backwards compatible overload for use with services derived from
+  // io_context::service.
+  template <typename Service>
+  friend Service& use_service(io_context& ioc);
+
+#if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
+  detail::winsock_init<> init_;
+#elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
+  || defined(__osf__)
+  detail::signal_init<> init_;
+#endif
+
+  // The implementation.
+  impl_type& impl_;
+};
+
+/// Executor used to submit functions to an io_context.
+class io_context::executor_type
+{
+public:
+  /// Obtain the underlying execution context.
+  io_context& context() const BOOST_ASIO_NOEXCEPT;
+
+  /// Inform the io_context that it has some outstanding work to do.
+  /**
+   * This function is used to inform the io_context that some work has begun.
+   * This ensures that the io_context's run() and run_one() functions do not
+   * exit while the work is underway.
+   */
+  void on_work_started() const BOOST_ASIO_NOEXCEPT;
+
+  /// Inform the io_context that some work is no longer outstanding.
+  /**
+   * This function is used to inform the io_context that some work has
+   * finished. Once the count of unfinished work reaches zero, the io_context
+   * is stopped and the run() and run_one() functions may exit.
+   */
+  void on_work_finished() const BOOST_ASIO_NOEXCEPT;
+
+  /// Request the io_context to invoke the given function object.
+  /**
+   * This function is used to ask the io_context to execute the given function
+   * object. If the current thread is running the io_context, @c dispatch()
+   * executes the function before returning. Otherwise, the function will be
+   * scheduled to run on the io_context.
+   *
+   * @param f The function object to be called. The executor will make a copy
+   * of the handler object as required. The function signature of the function
+   * object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the io_context to invoke the given function object.
+  /**
+   * This function is used to ask the io_context to execute the given function
+   * object. The function object will never be executed inside @c post().
+   * Instead, it will be scheduled to run on the io_context.
+   *
+   * @param f The function object to be called. The executor will make a copy
+   * of the handler object as required. The function signature of the function
+   * object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the io_context to invoke the given function object.
+  /**
+   * This function is used to ask the io_context to execute the given function
+   * object. The function object will never be executed inside @c defer().
+   * Instead, it will be scheduled to run on the io_context.
+   *
+   * If the current thread belongs to the io_context, @c defer() will delay
+   * scheduling the function object until the current thread returns control to
+   * the pool.
+   *
+   * @param f The function object to be called. The executor will make a copy
+   * of the handler object as required. The function signature of the function
+   * object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Determine whether the io_context is running in the current thread.
+  /**
+   * @return @c true if the current thread is running the io_context. Otherwise
+   * returns @c false.
+   */
+  bool running_in_this_thread() const BOOST_ASIO_NOEXCEPT;
+
+  /// Compare two executors for equality.
+  /**
+   * Two executors are equal if they refer to the same underlying io_context.
+   */
+  friend bool operator==(const executor_type& a,
+      const executor_type& b) BOOST_ASIO_NOEXCEPT
+  {
+    return &a.io_context_ == &b.io_context_;
+  }
+
+  /// Compare two executors for inequality.
+  /**
+   * Two executors are equal if they refer to the same underlying io_context.
+   */
+  friend bool operator!=(const executor_type& a,
+      const executor_type& b) BOOST_ASIO_NOEXCEPT
+  {
+    return &a.io_context_ != &b.io_context_;
+  }
+
+private:
+  friend class io_context;
+
+  // Constructor.
+  explicit executor_type(io_context& i) : io_context_(i) {}
+
+  // The underlying io_context.
+  io_context& io_context_;
+};
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+/// (Deprecated: Use executor_work_guard.) Class to inform the io_context when
+/// it has work to do.
+/**
+ * The work class is used to inform the io_context when work starts and
+ * finishes. This ensures that the io_context object's run() function will not
+ * exit while work is underway, and that it does exit when there is no
+ * unfinished work remaining.
+ *
+ * The work class is copy-constructible so that it may be used as a data member
+ * in a handler class. It is not assignable.
+ */
+class io_context::work
+{
+public:
+  /// Constructor notifies the io_context that work is starting.
+  /**
+   * The constructor is used to inform the io_context that some work has begun.
+   * This ensures that the io_context object's run() function will not exit
+   * while the work is underway.
+   */
+  explicit work(boost::asio::io_context& io_context);
+
+  /// Copy constructor notifies the io_context that work is starting.
+  /**
+   * The constructor is used to inform the io_context that some work has begun.
+   * This ensures that the io_context object's run() function will not exit
+   * while the work is underway.
+   */
+  work(const work& other);
+
+  /// Destructor notifies the io_context that the work is complete.
+  /**
+   * The destructor is used to inform the io_context that some work has
+   * finished. Once the count of unfinished work reaches zero, the io_context
+   * object's run() function is permitted to exit.
+   */
+  ~work();
+
+  /// Get the io_context associated with the work.
+  boost::asio::io_context& get_io_context();
+
+  /// (Deprecated: Use get_io_context().) Get the io_context associated with the
+  /// work.
+  boost::asio::io_context& get_io_service();
+
+private:
+  // Prevent assignment.
+  void operator=(const work& other);
+
+  // The io_context implementation.
+  detail::io_context_impl& io_context_impl_;
+};
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+/// Base class for all io_context services.
+class io_context::service
+  : public execution_context::service
+{
+public:
+  /// Get the io_context object that owns the service.
+  boost::asio::io_context& get_io_context();
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// Get the io_context object that owns the service.
+  boost::asio::io_context& get_io_service();
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+private:
+  /// Destroy all user-defined handler objects owned by the service.
+  BOOST_ASIO_DECL virtual void shutdown();
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use shutdown().) Destroy all user-defined handler objects
+  /// owned by the service.
+  BOOST_ASIO_DECL virtual void shutdown_service();
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Handle notification of a fork-related event to perform any necessary
+  /// housekeeping.
+  /**
+   * This function is not a pure virtual so that services only have to
+   * implement it if necessary. The default implementation does nothing.
+   */
+  BOOST_ASIO_DECL virtual void notify_fork(
+      execution_context::fork_event event);
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use notify_fork().) Handle notification of a fork-related
+  /// event to perform any necessary housekeeping.
+  /**
+   * This function is not a pure virtual so that services only have to
+   * implement it if necessary. The default implementation does nothing.
+   */
+  BOOST_ASIO_DECL virtual void fork_service(
+      execution_context::fork_event event);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+protected:
+  /// Constructor.
+  /**
+   * @param owner The io_context object that owns the service.
+   */
+  BOOST_ASIO_DECL service(boost::asio::io_context& owner);
+
+  /// Destructor.
+  BOOST_ASIO_DECL virtual ~service();
+};
+
+namespace detail {
+
+// Special service base class to keep classes header-file only.
+template <typename Type>
+class service_base
+  : public boost::asio::io_context::service
+{
+public:
+  static boost::asio::detail::service_id<Type> id;
+
+  // Constructor.
+  service_base(boost::asio::io_context& io_context)
+    : boost::asio::io_context::service(io_context)
+  {
+  }
+};
+
+template <typename Type>
+boost::asio::detail::service_id<Type> service_base<Type>::id;
+
+} // namespace detail
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/io_context.hpp>
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/impl/io_context.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+// If both io_context.hpp and strand.hpp have been included, automatically
+// include the header file needed for the io_context::strand class.
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+# if defined(BOOST_ASIO_STRAND_HPP)
+#  include <boost/asio/io_context_strand.hpp>
+# endif // defined(BOOST_ASIO_STRAND_HPP)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
+#endif // BOOST_ASIO_IO_CONTEXT_HPP
diff --git a/include/boost/asio/io_context_strand.hpp b/include/boost/asio/io_context_strand.hpp
new file mode 100644
index 0000000000..2190a7b7db
--- /dev/null
+++ b/include/boost/asio/io_context_strand.hpp
@@ -0,0 +1,384 @@
+//
+// io_context_strand.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IO_CONTEXT_STRAND_HPP
+#define BOOST_ASIO_IO_CONTEXT_STRAND_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/strand_service.hpp>
+#include <boost/asio/detail/wrapped_handler.hpp>
+#include <boost/asio/io_context.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// Provides serialised handler execution.
+/**
+ * The io_context::strand class provides the ability to post and dispatch
+ * handlers with the guarantee that none of those handlers will execute
+ * concurrently.
+ *
+ * @par Order of handler invocation
+ * Given:
+ *
+ * @li a strand object @c s
+ *
+ * @li an object @c a meeting completion handler requirements
+ *
+ * @li an object @c a1 which is an arbitrary copy of @c a made by the
+ * implementation
+ *
+ * @li an object @c b meeting completion handler requirements
+ *
+ * @li an object @c b1 which is an arbitrary copy of @c b made by the
+ * implementation
+ *
+ * if any of the following conditions are true:
+ *
+ * @li @c s.post(a) happens-before @c s.post(b)
+ * 
+ * @li @c s.post(a) happens-before @c s.dispatch(b), where the latter is
+ * performed outside the strand
+ * 
+ * @li @c s.dispatch(a) happens-before @c s.post(b), where the former is
+ * performed outside the strand
+ * 
+ * @li @c s.dispatch(a) happens-before @c s.dispatch(b), where both are
+ * performed outside the strand
+ *   
+ * then @c asio_handler_invoke(a1, &a1) happens-before
+ * @c asio_handler_invoke(b1, &b1).
+ * 
+ * Note that in the following case:
+ * @code async_op_1(..., s.wrap(a));
+ * async_op_2(..., s.wrap(b)); @endcode
+ * the completion of the first async operation will perform @c s.dispatch(a),
+ * and the second will perform @c s.dispatch(b), but the order in which those
+ * are performed is unspecified. That is, you cannot state whether one
+ * happens-before the other. Therefore none of the above conditions are met and
+ * no ordering guarantee is made.
+ *
+ * @note The implementation makes no guarantee that handlers posted or
+ * dispatched through different @c strand objects will be invoked concurrently.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Safe.
+ *
+ * @par Concepts:
+ * Dispatcher.
+ */
+class io_context::strand
+{
+public:
+  /// Constructor.
+  /**
+   * Constructs the strand.
+   *
+   * @param io_context The io_context object that the strand will use to
+   * dispatch handlers that are ready to be run.
+   */
+  explicit strand(boost::asio::io_context& io_context)
+    : service_(boost::asio::use_service<
+        boost::asio::detail::strand_service>(io_context))
+  {
+    service_.construct(impl_);
+  }
+
+  /// Destructor.
+  /**
+   * Destroys a strand.
+   *
+   * Handlers posted through the strand that have not yet been invoked will
+   * still be dispatched in a way that meets the guarantee of non-concurrency.
+   */
+  ~strand()
+  {
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use context().) Get the io_context associated with the
+  /// strand.
+  /**
+   * This function may be used to obtain the io_context object that the strand
+   * uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the strand will use to
+   * dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return service_.get_io_context();
+  }
+
+  /// (Deprecated: Use context().) Get the io_context associated with the
+  /// strand.
+  /**
+   * This function may be used to obtain the io_context object that the strand
+   * uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the strand will use to
+   * dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return service_.get_io_context();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Obtain the underlying execution context.
+  boost::asio::io_context& context() const BOOST_ASIO_NOEXCEPT
+  {
+    return service_.get_io_context();
+  }
+
+  /// Inform the strand that it has some outstanding work to do.
+  /**
+   * The strand delegates this call to its underlying io_context.
+   */
+  void on_work_started() const BOOST_ASIO_NOEXCEPT
+  {
+    context().get_executor().on_work_started();
+  }
+
+  /// Inform the strand that some work is no longer outstanding.
+  /**
+   * The strand delegates this call to its underlying io_context.
+   */
+  void on_work_finished() const BOOST_ASIO_NOEXCEPT
+  {
+    context().get_executor().on_work_finished();
+  }
+
+  /// Request the strand to invoke the given function object.
+  /**
+   * This function is used to ask the strand to execute the given function
+   * object on its underlying io_context. The function object will be executed
+   * inside this function if the strand is not otherwise busy and if the
+   * underlying io_context's executor's @c dispatch() function is also able to
+   * execute the function before returning.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+  {
+    typename decay<Function>::type tmp(BOOST_ASIO_MOVE_CAST(Function)(f));
+    service_.dispatch(impl_, tmp);
+    (void)a;
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use boost::asio::dispatch().) Request the strand to invoke
+  /// the given handler.
+  /**
+   * This function is used to ask the strand to execute the given handler.
+   *
+   * The strand object guarantees that handlers posted or dispatched through
+   * the strand will not be executed concurrently. The handler may be executed
+   * inside this function if the guarantee can be met. If this function is
+   * called from within a handler that was posted or dispatched through the same
+   * strand, then the new handler will be executed immediately.
+   *
+   * The strand's guarantee is in addition to the guarantee provided by the
+   * underlying io_context. The io_context guarantees that the handler will only
+   * be called in a thread in which the io_context's run member function is
+   * currently being invoked.
+   *
+   * @param handler The handler to be called. The strand will make a copy of the
+   * handler object as required. The function signature of the handler must be:
+   * @code void handler(); @endcode
+   */
+  template <typename CompletionHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
+  dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a CompletionHandler.
+    BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
+
+    async_completion<CompletionHandler, void ()> init(handler);
+
+    service_.dispatch(impl_, init.completion_handler);
+
+    return init.result.get();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Request the strand to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object will never be executed inside this function.
+   * Instead, it will be scheduled to run by the underlying io_context.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+  {
+    typename decay<Function>::type tmp(BOOST_ASIO_MOVE_CAST(Function)(f));
+    service_.post(impl_, tmp);
+    (void)a;
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use boost::asio::post().) Request the strand to invoke the
+  /// given handler and return immediately.
+  /**
+   * This function is used to ask the strand to execute the given handler, but
+   * without allowing the strand to call the handler from inside this function.
+   *
+   * The strand object guarantees that handlers posted or dispatched through
+   * the strand will not be executed concurrently. The strand's guarantee is in
+   * addition to the guarantee provided by the underlying io_context. The
+   * io_context guarantees that the handler will only be called in a thread in
+   * which the io_context's run member function is currently being invoked.
+   *
+   * @param handler The handler to be called. The strand will make a copy of the
+   * handler object as required. The function signature of the handler must be:
+   * @code void handler(); @endcode
+   */
+  template <typename CompletionHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
+  post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a CompletionHandler.
+    BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
+
+    async_completion<CompletionHandler, void ()> init(handler);
+
+    service_.post(impl_, init.completion_handler);
+
+    return init.result.get();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Request the strand to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object will never be executed inside this function.
+   * Instead, it will be scheduled to run by the underlying io_context.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+  {
+    typename decay<Function>::type tmp(BOOST_ASIO_MOVE_CAST(Function)(f));
+    service_.post(impl_, tmp);
+    (void)a;
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use boost::asio::bind_executor().) Create a new handler that
+  /// automatically dispatches the wrapped handler on the strand.
+  /**
+   * This function is used to create a new handler function object that, when
+   * invoked, will automatically pass the wrapped handler to the strand's
+   * dispatch function.
+   *
+   * @param handler The handler to be wrapped. The strand will make a copy of
+   * the handler object as required. The function signature of the handler must
+   * be: @code void handler(A1 a1, ... An an); @endcode
+   *
+   * @return A function object that, when invoked, passes the wrapped handler to
+   * the strand's dispatch function. Given a function object with the signature:
+   * @code R f(A1 a1, ... An an); @endcode
+   * If this function object is passed to the wrap function like so:
+   * @code strand.wrap(f); @endcode
+   * then the return value is a function object with the signature
+   * @code void g(A1 a1, ... An an); @endcode
+   * that, when invoked, executes code equivalent to:
+   * @code strand.dispatch(boost::bind(f, a1, ... an)); @endcode
+   */
+  template <typename Handler>
+#if defined(GENERATING_DOCUMENTATION)
+  unspecified
+#else
+  detail::wrapped_handler<strand, Handler, detail::is_continuation_if_running>
+#endif
+  wrap(Handler handler)
+  {
+    return detail::wrapped_handler<io_context::strand, Handler,
+        detail::is_continuation_if_running>(*this, handler);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Determine whether the strand is running in the current thread.
+  /**
+   * @return @c true if the current thread is executing a handler that was
+   * submitted to the strand using post(), dispatch() or wrap(). Otherwise
+   * returns @c false.
+   */
+  bool running_in_this_thread() const BOOST_ASIO_NOEXCEPT
+  {
+    return service_.running_in_this_thread(impl_);
+  }
+
+  /// Compare two strands for equality.
+  /**
+   * Two strands are equal if they refer to the same ordered, non-concurrent
+   * state.
+   */
+  friend bool operator==(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
+  {
+    return a.impl_ == b.impl_;
+  }
+
+  /// Compare two strands for inequality.
+  /**
+   * Two strands are equal if they refer to the same ordered, non-concurrent
+   * state.
+   */
+  friend bool operator!=(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
+  {
+    return a.impl_ != b.impl_;
+  }
+
+private:
+  boost::asio::detail::strand_service& service_;
+  mutable boost::asio::detail::strand_service::implementation_type impl_;
+};
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
+#endif // BOOST_ASIO_IO_CONTEXT_STRAND_HPP
diff --git a/include/boost/asio/io_service.hpp b/include/boost/asio/io_service.hpp
index f2b4667311..b04424dd69 100644
--- a/include/boost/asio/io_service.hpp
+++ b/include/boost/asio/io_service.hpp
@@ -15,758 +15,21 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
-#include <boost/asio/detail/config.hpp>
-#include <cstddef>
-#include <stdexcept>
-#include <typeinfo>
-#include <boost/asio/async_result.hpp>
-#include <boost/asio/detail/noncopyable.hpp>
-#include <boost/asio/detail/wrapped_handler.hpp>
-#include <boost/system/error_code.hpp>
-
-#if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
-# include <boost/asio/detail/winsock_init.hpp>
-#elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
-  || defined(__osf__)
-# include <boost/asio/detail/signal_init.hpp>
-#endif
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
-class io_service;
-template <typename Service> Service& use_service(io_service& ios);
-template <typename Service> void add_service(io_service& ios, Service* svc);
-template <typename Service> bool has_service(io_service& ios);
-
-namespace detail {
-#if defined(BOOST_ASIO_HAS_IOCP)
-  typedef class win_iocp_io_service io_service_impl;
-  class win_iocp_overlapped_ptr;
-#else
-  typedef class task_io_service io_service_impl;
-#endif
-  class service_registry;
-} // namespace detail
-
-/// Provides core I/O functionality.
-/**
- * The io_service class provides the core I/O functionality for users of the
- * asynchronous I/O objects, including:
- *
- * @li boost::asio::ip::tcp::socket
- * @li boost::asio::ip::tcp::acceptor
- * @li boost::asio::ip::udp::socket
- * @li boost::asio::deadline_timer.
- *
- * The io_service class also includes facilities intended for developers of
- * custom asynchronous services.
- *
- * @par Thread Safety
- * @e Distinct @e objects: Safe.@n
- * @e Shared @e objects: Safe, with the specific exceptions of the reset() and
- * notify_fork() functions. Calling reset() while there are unfinished run(),
- * run_one(), poll() or poll_one() calls results in undefined behaviour. The
- * notify_fork() function should not be called while any io_service function,
- * or any function on an I/O object that is associated with the io_service, is
- * being called in another thread.
- *
- * @par Concepts:
- * Dispatcher.
- *
- * @par Synchronous and asynchronous operations
- *
- * Synchronous operations on I/O objects implicitly run the io_service object
- * for an individual operation. The io_service functions run(), run_one(),
- * poll() or poll_one() must be called for the io_service to perform
- * asynchronous operations on behalf of a C++ program. Notification that an
- * asynchronous operation has completed is delivered by invocation of the
- * associated handler. Handlers are invoked only by a thread that is currently
- * calling any overload of run(), run_one(), poll() or poll_one() for the
- * io_service.
- *
- * @par Effect of exceptions thrown from handlers
- *
- * If an exception is thrown from a handler, the exception is allowed to
- * propagate through the throwing thread's invocation of run(), run_one(),
- * poll() or poll_one(). No other threads that are calling any of these
- * functions are affected. It is then the responsibility of the application to
- * catch the exception.
- *
- * After the exception has been caught, the run(), run_one(), poll() or
- * poll_one() call may be restarted @em without the need for an intervening
- * call to reset(). This allows the thread to rejoin the io_service object's
- * thread pool without impacting any other threads in the pool.
- *
- * For example:
- *
- * @code
- * boost::asio::io_service io_service;
- * ...
- * for (;;)
- * {
- *   try
- *   {
- *     io_service.run();
- *     break; // run() exited normally
- *   }
- *   catch (my_exception& e)
- *   {
- *     // Deal with exception as appropriate.
- *   }
- * }
- * @endcode
- *
- * @par Stopping the io_service from running out of work
- *
- * Some applications may need to prevent an io_service object's run() call from
- * returning when there is no more work to do. For example, the io_service may
- * be being run in a background thread that is launched prior to the
- * application's asynchronous operations. The run() call may be kept running by
- * creating an object of type boost::asio::io_service::work:
- *
- * @code boost::asio::io_service io_service;
- * boost::asio::io_service::work work(io_service);
- * ... @endcode
- *
- * To effect a shutdown, the application will then need to call the io_service
- * object's stop() member function. This will cause the io_service run() call
- * to return as soon as possible, abandoning unfinished operations and without
- * permitting ready handlers to be dispatched.
- *
- * Alternatively, if the application requires that all operations and handlers
- * be allowed to finish normally, the work object may be explicitly destroyed.
- *
- * @code boost::asio::io_service io_service;
- * auto_ptr<boost::asio::io_service::work> work(
- *     new boost::asio::io_service::work(io_service));
- * ...
- * work.reset(); // Allow run() to exit. @endcode
- *
- * @par The io_service class and I/O services
- *
- * Class io_service implements an extensible, type-safe, polymorphic set of I/O
- * services, indexed by service type. An object of class io_service must be
- * initialised before I/O objects such as sockets, resolvers and timers can be
- * used. These I/O objects are distinguished by having constructors that accept
- * an @c io_service& parameter.
- *
- * I/O services exist to manage the logical interface to the operating system on
- * behalf of the I/O objects. In particular, there are resources that are shared
- * across a class of I/O objects. For example, timers may be implemented in
- * terms of a single timer queue. The I/O services manage these shared
- * resources.
- *
- * Access to the services of an io_service is via three function templates,
- * use_service(), add_service() and has_service().
- *
- * In a call to @c use_service<Service>(), the type argument chooses a service,
- * making available all members of the named type. If @c Service is not present
- * in an io_service, an object of type @c Service is created and added to the
- * io_service. A C++ program can check if an io_service implements a
- * particular service with the function template @c has_service<Service>().
- *
- * Service objects may be explicitly added to an io_service using the function
- * template @c add_service<Service>(). If the @c Service is already present, the
- * service_already_exists exception is thrown. If the owner of the service is
- * not the same object as the io_service parameter, the invalid_service_owner
- * exception is thrown.
- *
- * Once a service reference is obtained from an io_service object by calling
- * use_service(), that reference remains usable as long as the owning io_service
- * object exists.
- *
- * All I/O service implementations have io_service::service as a public base
- * class. Custom I/O services may be implemented by deriving from this class and
- * then added to an io_service using the facilities described above.
- */
-class io_service
-  : private noncopyable
-{
-private:
-  typedef detail::io_service_impl impl_type;
-#if defined(BOOST_ASIO_HAS_IOCP)
-  friend class detail::win_iocp_overlapped_ptr;
-#endif
-
-public:
-  class work;
-  friend class work;
-
-  class id;
-
-  class service;
-
-  class strand;
-
-  /// Constructor.
-  BOOST_ASIO_DECL io_service();
-
-  /// Constructor.
-  /**
-   * Construct with a hint about the required level of concurrency.
-   *
-   * @param concurrency_hint A suggestion to the implementation on how many
-   * threads it should allow to run simultaneously.
-   */
-  BOOST_ASIO_DECL explicit io_service(std::size_t concurrency_hint);
-
-  /// Destructor.
-  /**
-   * On destruction, the io_service performs the following sequence of
-   * operations:
-   *
-   * @li For each service object @c svc in the io_service set, in reverse order
-   * of the beginning of service object lifetime, performs
-   * @c svc->shutdown_service().
-   *
-   * @li Uninvoked handler objects that were scheduled for deferred invocation
-   * on the io_service, or any associated strand, are destroyed.
-   *
-   * @li For each service object @c svc in the io_service set, in reverse order
-   * of the beginning of service object lifetime, performs
-   * <tt>delete static_cast<io_service::service*>(svc)</tt>.
-   *
-   * @note The destruction sequence described above permits programs to
-   * simplify their resource management by using @c shared_ptr<>. Where an
-   * object's lifetime is tied to the lifetime of a connection (or some other
-   * sequence of asynchronous operations), a @c shared_ptr to the object would
-   * be bound into the handlers for all asynchronous operations associated with
-   * it. This works as follows:
-   *
-   * @li When a single connection ends, all associated asynchronous operations
-   * complete. The corresponding handler objects are destroyed, and all
-   * @c shared_ptr references to the objects are destroyed.
-   *
-   * @li To shut down the whole program, the io_service function stop() is
-   * called to terminate any run() calls as soon as possible. The io_service
-   * destructor defined above destroys all handlers, causing all @c shared_ptr
-   * references to all connection objects to be destroyed.
-   */
-  BOOST_ASIO_DECL ~io_service();
-
-  /// Run the io_service object's event processing loop.
-  /**
-   * The run() function blocks until all work has finished and there are no
-   * more handlers to be dispatched, or until the io_service has been stopped.
-   *
-   * Multiple threads may call the run() function to set up a pool of threads
-   * from which the io_service may execute handlers. All threads that are
-   * waiting in the pool are equivalent and the io_service may choose any one
-   * of them to invoke a handler.
-   *
-   * A normal exit from the run() function implies that the io_service object
-   * is stopped (the stopped() function returns @c true). Subsequent calls to
-   * run(), run_one(), poll() or poll_one() will return immediately unless there
-   * is a prior call to reset().
-   *
-   * @return The number of handlers that were executed.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   *
-   * @note The run() function must not be called from a thread that is currently
-   * calling one of run(), run_one(), poll() or poll_one() on the same
-   * io_service object.
-   *
-   * The poll() function may also be used to dispatch ready handlers, but
-   * without blocking.
-   */
-  BOOST_ASIO_DECL std::size_t run();
-
-  /// Run the io_service object's event processing loop.
-  /**
-   * The run() function blocks until all work has finished and there are no
-   * more handlers to be dispatched, or until the io_service has been stopped.
-   *
-   * Multiple threads may call the run() function to set up a pool of threads
-   * from which the io_service may execute handlers. All threads that are
-   * waiting in the pool are equivalent and the io_service may choose any one
-   * of them to invoke a handler.
-   *
-   * A normal exit from the run() function implies that the io_service object
-   * is stopped (the stopped() function returns @c true). Subsequent calls to
-   * run(), run_one(), poll() or poll_one() will return immediately unless there
-   * is a prior call to reset().
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   *
-   * @return The number of handlers that were executed.
-   *
-   * @note The run() function must not be called from a thread that is currently
-   * calling one of run(), run_one(), poll() or poll_one() on the same
-   * io_service object.
-   *
-   * The poll() function may also be used to dispatch ready handlers, but
-   * without blocking.
-   */
-  BOOST_ASIO_DECL std::size_t run(boost::system::error_code& ec);
-
-  /// Run the io_service object's event processing loop to execute at most one
-  /// handler.
-  /**
-   * The run_one() function blocks until one handler has been dispatched, or
-   * until the io_service has been stopped.
-   *
-   * @return The number of handlers that were executed. A zero return value
-   * implies that the io_service object is stopped (the stopped() function
-   * returns @c true). Subsequent calls to run(), run_one(), poll() or
-   * poll_one() will return immediately unless there is a prior call to
-   * reset().
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  BOOST_ASIO_DECL std::size_t run_one();
-
-  /// Run the io_service object's event processing loop to execute at most one
-  /// handler.
-  /**
-   * The run_one() function blocks until one handler has been dispatched, or
-   * until the io_service has been stopped.
-   *
-   * @return The number of handlers that were executed. A zero return value
-   * implies that the io_service object is stopped (the stopped() function
-   * returns @c true). Subsequent calls to run(), run_one(), poll() or
-   * poll_one() will return immediately unless there is a prior call to
-   * reset().
-   *
-   * @return The number of handlers that were executed.
-   */
-  BOOST_ASIO_DECL std::size_t run_one(boost::system::error_code& ec);
-
-  /// Run the io_service object's event processing loop to execute ready
-  /// handlers.
-  /**
-   * The poll() function runs handlers that are ready to run, without blocking,
-   * until the io_service has been stopped or there are no more ready handlers.
-   *
-   * @return The number of handlers that were executed.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  BOOST_ASIO_DECL std::size_t poll();
-
-  /// Run the io_service object's event processing loop to execute ready
-  /// handlers.
-  /**
-   * The poll() function runs handlers that are ready to run, without blocking,
-   * until the io_service has been stopped or there are no more ready handlers.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   *
-   * @return The number of handlers that were executed.
-   */
-  BOOST_ASIO_DECL std::size_t poll(boost::system::error_code& ec);
-
-  /// Run the io_service object's event processing loop to execute one ready
-  /// handler.
-  /**
-   * The poll_one() function runs at most one handler that is ready to run,
-   * without blocking.
-   *
-   * @return The number of handlers that were executed.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  BOOST_ASIO_DECL std::size_t poll_one();
-
-  /// Run the io_service object's event processing loop to execute one ready
-  /// handler.
-  /**
-   * The poll_one() function runs at most one handler that is ready to run,
-   * without blocking.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   *
-   * @return The number of handlers that were executed.
-   */
-  BOOST_ASIO_DECL std::size_t poll_one(boost::system::error_code& ec);
-
-  /// Stop the io_service object's event processing loop.
-  /**
-   * This function does not block, but instead simply signals the io_service to
-   * stop. All invocations of its run() or run_one() member functions should
-   * return as soon as possible. Subsequent calls to run(), run_one(), poll()
-   * or poll_one() will return immediately until reset() is called.
-   */
-  BOOST_ASIO_DECL void stop();
-
-  /// Determine whether the io_service object has been stopped.
-  /**
-   * This function is used to determine whether an io_service object has been
-   * stopped, either through an explicit call to stop(), or due to running out
-   * of work. When an io_service object is stopped, calls to run(), run_one(),
-   * poll() or poll_one() will return immediately without invoking any
-   * handlers.
-   *
-   * @return @c true if the io_service object is stopped, otherwise @c false.
-   */
-  BOOST_ASIO_DECL bool stopped() const;
-
-  /// Reset the io_service in preparation for a subsequent run() invocation.
-  /**
-   * This function must be called prior to any second or later set of
-   * invocations of the run(), run_one(), poll() or poll_one() functions when a
-   * previous invocation of these functions returned due to the io_service
-   * being stopped or running out of work. After a call to reset(), the
-   * io_service object's stopped() function will return @c false.
-   *
-   * This function must not be called while there are any unfinished calls to
-   * the run(), run_one(), poll() or poll_one() functions.
-   */
-  BOOST_ASIO_DECL void reset();
-
-  /// Request the io_service to invoke the given handler.
-  /**
-   * This function is used to ask the io_service to execute the given handler.
-   *
-   * The io_service guarantees that the handler will only be called in a thread
-   * in which the run(), run_one(), poll() or poll_one() member functions is
-   * currently being invoked. The handler may be executed inside this function
-   * if the guarantee can be met.
-   *
-   * @param handler The handler to be called. The io_service will make
-   * a copy of the handler object as required. The function signature of the
-   * handler must be: @code void handler(); @endcode
-   *
-   * @note This function throws an exception only if:
-   *
-   * @li the handler's @c asio_handler_allocate function; or
-   *
-   * @li the handler's copy constructor
-   *
-   * throws an exception.
-   */
-  template <typename CompletionHandler>
-  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
-  dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
-
-  /// Request the io_service to invoke the given handler and return immediately.
-  /**
-   * This function is used to ask the io_service to execute the given handler,
-   * but without allowing the io_service to call the handler from inside this
-   * function.
-   *
-   * The io_service guarantees that the handler will only be called in a thread
-   * in which the run(), run_one(), poll() or poll_one() member functions is
-   * currently being invoked.
-   *
-   * @param handler The handler to be called. The io_service will make
-   * a copy of the handler object as required. The function signature of the
-   * handler must be: @code void handler(); @endcode
-   *
-   * @note This function throws an exception only if:
-   *
-   * @li the handler's @c asio_handler_allocate function; or
-   *
-   * @li the handler's copy constructor
-   *
-   * throws an exception.
-   */
-  template <typename CompletionHandler>
-  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
-  post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler);
-
-  /// Create a new handler that automatically dispatches the wrapped handler
-  /// on the io_service.
-  /**
-   * This function is used to create a new handler function object that, when
-   * invoked, will automatically pass the wrapped handler to the io_service
-   * object's dispatch function.
-   *
-   * @param handler The handler to be wrapped. The io_service will make a copy
-   * of the handler object as required. The function signature of the handler
-   * must be: @code void handler(A1 a1, ... An an); @endcode
-   *
-   * @return A function object that, when invoked, passes the wrapped handler to
-   * the io_service object's dispatch function. Given a function object with the
-   * signature:
-   * @code R f(A1 a1, ... An an); @endcode
-   * If this function object is passed to the wrap function like so:
-   * @code io_service.wrap(f); @endcode
-   * then the return value is a function object with the signature
-   * @code void g(A1 a1, ... An an); @endcode
-   * that, when invoked, executes code equivalent to:
-   * @code io_service.dispatch(boost::bind(f, a1, ... an)); @endcode
-   */
-  template <typename Handler>
-#if defined(GENERATING_DOCUMENTATION)
-  unspecified
-#else
-  detail::wrapped_handler<io_service&, Handler>
-#endif
-  wrap(Handler handler);
-
-  /// Fork-related event notifications.
-  enum fork_event
-  {
-    /// Notify the io_service that the process is about to fork.
-    fork_prepare,
-
-    /// Notify the io_service that the process has forked and is the parent.
-    fork_parent,
-
-    /// Notify the io_service that the process has forked and is the child.
-    fork_child
-  };
-
-  /// Notify the io_service of a fork-related event.
-  /**
-   * This function is used to inform the io_service that the process is about
-   * to fork, or has just forked. This allows the io_service, and the services
-   * it contains, to perform any necessary housekeeping to ensure correct
-   * operation following a fork.
-   *
-   * This function must not be called while any other io_service function, or
-   * any function on an I/O object associated with the io_service, is being
-   * called in another thread. It is, however, safe to call this function from
-   * within a completion handler, provided no other thread is accessing the
-   * io_service.
-   *
-   * @param event A fork-related event.
-   *
-   * @throws boost::system::system_error Thrown on failure. If the notification
-   * fails the io_service object should no longer be used and should be
-   * destroyed.
-   *
-   * @par Example
-   * The following code illustrates how to incorporate the notify_fork()
-   * function:
-   * @code my_io_service.notify_fork(boost::asio::io_service::fork_prepare);
-   * if (fork() == 0)
-   * {
-   *   // This is the child process.
-   *   my_io_service.notify_fork(boost::asio::io_service::fork_child);
-   * }
-   * else
-   * {
-   *   // This is the parent process.
-   *   my_io_service.notify_fork(boost::asio::io_service::fork_parent);
-   * } @endcode
-   *
-   * @note For each service object @c svc in the io_service set, performs
-   * <tt>svc->fork_service();</tt>. When processing the fork_prepare event,
-   * services are visited in reverse order of the beginning of service object
-   * lifetime. Otherwise, services are visited in order of the beginning of
-   * service object lifetime.
-   */
-  BOOST_ASIO_DECL void notify_fork(boost::asio::io_service::fork_event event);
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+/// Typedef for backwards compatibility.
+typedef io_context io_service;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-  /// Obtain the service object corresponding to the given type.
-  /**
-   * This function is used to locate a service object that corresponds to
-   * the given service type. If there is no existing implementation of the
-   * service, then the io_service will create a new instance of the service.
-   *
-   * @param ios The io_service object that owns the service.
-   *
-   * @return The service interface implementing the specified service type.
-   * Ownership of the service interface is not transferred to the caller.
-   */
-  template <typename Service>
-  friend Service& use_service(io_service& ios);
-
-  /// Add a service object to the io_service.
-  /**
-   * This function is used to add a service to the io_service.
-   *
-   * @param ios The io_service object that owns the service.
-   *
-   * @param svc The service object. On success, ownership of the service object
-   * is transferred to the io_service. When the io_service object is destroyed,
-   * it will destroy the service object by performing:
-   * @code delete static_cast<io_service::service*>(svc) @endcode
-   *
-   * @throws boost::asio::service_already_exists Thrown if a service of the
-   * given type is already present in the io_service.
-   *
-   * @throws boost::asio::invalid_service_owner Thrown if the service's owning
-   * io_service is not the io_service object specified by the ios parameter.
-   */
-  template <typename Service>
-  friend void add_service(io_service& ios, Service* svc);
-
-  /// Determine if an io_service contains a specified service type.
-  /**
-   * This function is used to determine whether the io_service contains a
-   * service object corresponding to the given service type.
-   *
-   * @param ios The io_service object that owns the service.
-   *
-   * @return A boolean indicating whether the io_service contains the service.
-   */
-  template <typename Service>
-  friend bool has_service(io_service& ios);
-
-private:
-#if defined(BOOST_ASIO_WINDOWS) || defined(__CYGWIN__)
-  detail::winsock_init<> init_;
-#elif defined(__sun) || defined(__QNX__) || defined(__hpux) || defined(_AIX) \
-  || defined(__osf__)
-  detail::signal_init<> init_;
-#endif
-
-  // The service registry.
-  boost::asio::detail::service_registry* service_registry_;
-
-  // The implementation.
-  impl_type& impl_;
-};
-
-/// Class to inform the io_service when it has work to do.
-/**
- * The work class is used to inform the io_service when work starts and
- * finishes. This ensures that the io_service object's run() function will not
- * exit while work is underway, and that it does exit when there is no
- * unfinished work remaining.
- *
- * The work class is copy-constructible so that it may be used as a data member
- * in a handler class. It is not assignable.
- */
-class io_service::work
-{
-public:
-  /// Constructor notifies the io_service that work is starting.
-  /**
-   * The constructor is used to inform the io_service that some work has begun.
-   * This ensures that the io_service object's run() function will not exit
-   * while the work is underway.
-   */
-  explicit work(boost::asio::io_service& io_service);
-
-  /// Copy constructor notifies the io_service that work is starting.
-  /**
-   * The constructor is used to inform the io_service that some work has begun.
-   * This ensures that the io_service object's run() function will not exit
-   * while the work is underway.
-   */
-  work(const work& other);
-
-  /// Destructor notifies the io_service that the work is complete.
-  /**
-   * The destructor is used to inform the io_service that some work has
-   * finished. Once the count of unfinished work reaches zero, the io_service
-   * object's run() function is permitted to exit.
-   */
-  ~work();
-
-  /// Get the io_service associated with the work.
-  boost::asio::io_service& get_io_service();
-
-private:
-  // Prevent assignment.
-  void operator=(const work& other);
-
-  // The io_service implementation.
-  detail::io_service_impl& io_service_impl_;
-};
-
-/// Class used to uniquely identify a service.
-class io_service::id
-  : private noncopyable
-{
-public:
-  /// Constructor.
-  id() {}
-};
-
-/// Base class for all io_service services.
-class io_service::service
-  : private noncopyable
-{
-public:
-  /// Get the io_service object that owns the service.
-  boost::asio::io_service& get_io_service();
-
-protected:
-  /// Constructor.
-  /**
-   * @param owner The io_service object that owns the service.
-   */
-  BOOST_ASIO_DECL service(boost::asio::io_service& owner);
-
-  /// Destructor.
-  BOOST_ASIO_DECL virtual ~service();
-
-private:
-  /// Destroy all user-defined handler objects owned by the service.
-  virtual void shutdown_service() = 0;
-
-  /// Handle notification of a fork-related event to perform any necessary
-  /// housekeeping.
-  /**
-   * This function is not a pure virtual so that services only have to
-   * implement it if necessary. The default implementation does nothing.
-   */
-  BOOST_ASIO_DECL virtual void fork_service(
-      boost::asio::io_service::fork_event event);
-
-  friend class boost::asio::detail::service_registry;
-  struct key
-  {
-    key() : type_info_(0), id_(0) {}
-    const std::type_info* type_info_;
-    const boost::asio::io_service::id* id_;
-  } key_;
-
-  boost::asio::io_service& owner_;
-  service* next_;
-};
-
-/// Exception thrown when trying to add a duplicate service to an io_service.
-class service_already_exists
-  : public std::logic_error
-{
-public:
-  BOOST_ASIO_DECL service_already_exists();
-};
-
-/// Exception thrown when trying to add a service object to an io_service where
-/// the service has a different owner.
-class invalid_service_owner
-  : public std::logic_error
-{
-public:
-  BOOST_ASIO_DECL invalid_service_owner();
-};
-
-namespace detail {
-
-// Special derived service id type to keep classes header-file only.
-template <typename Type>
-class service_id
-  : public boost::asio::io_service::id
-{
-};
-
-// Special service base class to keep classes header-file only.
-template <typename Type>
-class service_base
-  : public boost::asio::io_service::service
-{
-public:
-  static boost::asio::detail::service_id<Type> id;
-
-  // Constructor.
-  service_base(boost::asio::io_service& io_service)
-    : boost::asio::io_service::service(io_service)
-  {
-  }
-};
-
-template <typename Type>
-boost::asio::detail::service_id<Type> service_base<Type>::id;
-
-} // namespace detail
 } // namespace asio
 } // namespace boost
 
 #include <boost/asio/detail/pop_options.hpp>
 
-#include <boost/asio/impl/io_service.hpp>
-#if defined(BOOST_ASIO_HEADER_ONLY)
-# include <boost/asio/impl/io_service.ipp>
-#endif // defined(BOOST_ASIO_HEADER_ONLY)
-
 #endif // BOOST_ASIO_IO_SERVICE_HPP
diff --git a/include/boost/asio/io_service_strand.hpp b/include/boost/asio/io_service_strand.hpp
new file mode 100644
index 0000000000..af7224a5a1
--- /dev/null
+++ b/include/boost/asio/io_service_strand.hpp
@@ -0,0 +1,20 @@
+//
+// io_service_strand.hpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IO_SERVICE_STRAND_HPP
+#define BOOST_ASIO_IO_SERVICE_STRAND_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/io_context_strand.hpp>
+
+#endif // BOOST_ASIO_IO_SERVICE_STRAND_HPP
diff --git a/include/boost/asio/ip/address.hpp b/include/boost/asio/ip/address.hpp
index 6e1b19e650..6d654b61b7 100644
--- a/include/boost/asio/ip/address.hpp
+++ b/include/boost/asio/ip/address.hpp
@@ -17,9 +17,13 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <string>
+#include <boost/asio/detail/throw_exception.hpp>
+#include <boost/asio/detail/string_view.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 #include <boost/system/error_code.hpp>
 #include <boost/asio/ip/address_v4.hpp>
 #include <boost/asio/ip/address_v6.hpp>
+#include <boost/asio/ip/bad_address_cast.hpp>
 
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 # include <iosfwd>
@@ -94,29 +98,34 @@ class address
   /// Get the address as an IP version 6 address.
   BOOST_ASIO_DECL boost::asio::ip::address_v6 to_v6() const;
 
-  /// Get the address as a string in dotted decimal format.
+  /// Get the address as a string.
   BOOST_ASIO_DECL std::string to_string() const;
 
-  /// Get the address as a string in dotted decimal format.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use other overload.) Get the address as a string.
   BOOST_ASIO_DECL std::string to_string(boost::system::error_code& ec) const;
 
-  /// Create an address from an IPv4 address string in dotted decimal form,
-  /// or from an IPv6 address in hexadecimal notation.
-  BOOST_ASIO_DECL static address from_string(const char* str);
-
-  /// Create an address from an IPv4 address string in dotted decimal form,
-  /// or from an IPv6 address in hexadecimal notation.
-  BOOST_ASIO_DECL static address from_string(
-      const char* str, boost::system::error_code& ec);
-
-  /// Create an address from an IPv4 address string in dotted decimal form,
-  /// or from an IPv6 address in hexadecimal notation.
-  BOOST_ASIO_DECL static address from_string(const std::string& str);
-
-  /// Create an address from an IPv4 address string in dotted decimal form,
-  /// or from an IPv6 address in hexadecimal notation.
-  BOOST_ASIO_DECL static address from_string(
+  /// (Deprecated: Use make_address().) Create an address from an IPv4 address
+  /// string in dotted decimal form, or from an IPv6 address in hexadecimal
+  /// notation.
+  static address from_string(const char* str);
+
+  /// (Deprecated: Use make_address().) Create an address from an IPv4 address
+  /// string in dotted decimal form, or from an IPv6 address in hexadecimal
+  /// notation.
+  static address from_string(const char* str, boost::system::error_code& ec);
+
+  /// (Deprecated: Use make_address().) Create an address from an IPv4 address
+  /// string in dotted decimal form, or from an IPv6 address in hexadecimal
+  /// notation.
+  static address from_string(const std::string& str);
+
+  /// (Deprecated: Use make_address().) Create an address from an IPv4 address
+  /// string in dotted decimal form, or from an IPv6 address in hexadecimal
+  /// notation.
+  static address from_string(
       const std::string& str, boost::system::error_code& ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Determine whether the address is a loopback address.
   BOOST_ASIO_DECL bool is_loopback() const;
@@ -168,6 +177,57 @@ class address
   boost::asio::ip::address_v6 ipv6_address_;
 };
 
+/// Create an address from an IPv4 address string in dotted decimal form,
+/// or from an IPv6 address in hexadecimal notation.
+/**
+ * @relates address
+ */
+BOOST_ASIO_DECL address make_address(const char* str);
+
+/// Create an address from an IPv4 address string in dotted decimal form,
+/// or from an IPv6 address in hexadecimal notation.
+/**
+ * @relates address
+ */
+BOOST_ASIO_DECL address make_address(
+    const char* str, boost::system::error_code& ec);
+
+/// Create an address from an IPv4 address string in dotted decimal form,
+/// or from an IPv6 address in hexadecimal notation.
+/**
+ * @relates address
+ */
+BOOST_ASIO_DECL address make_address(const std::string& str);
+
+/// Create an address from an IPv4 address string in dotted decimal form,
+/// or from an IPv6 address in hexadecimal notation.
+/**
+ * @relates address
+ */
+BOOST_ASIO_DECL address make_address(
+    const std::string& str, boost::system::error_code& ec);
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Create an address from an IPv4 address string in dotted decimal form,
+/// or from an IPv6 address in hexadecimal notation.
+/**
+ * @relates address
+ */
+BOOST_ASIO_DECL address make_address(string_view str);
+
+/// Create an address from an IPv4 address string in dotted decimal form,
+/// or from an IPv6 address in hexadecimal notation.
+/**
+ * @relates address
+ */
+BOOST_ASIO_DECL address make_address(
+    string_view str, boost::system::error_code& ec);
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+       //  || defined(GENERATING_DOCUMENTATION)
+
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Output an address as a string.
diff --git a/include/boost/asio/ip/address_v4.hpp b/include/boost/asio/ip/address_v4.hpp
index 3db4d4c825..399c051910 100644
--- a/include/boost/asio/ip/address_v4.hpp
+++ b/include/boost/asio/ip/address_v4.hpp
@@ -18,7 +18,9 @@
 #include <boost/asio/detail/config.hpp>
 #include <string>
 #include <boost/asio/detail/array.hpp>
+#include <boost/asio/detail/cstdint.hpp>
 #include <boost/asio/detail/socket_types.hpp>
+#include <boost/asio/detail/string_view.hpp>
 #include <boost/asio/detail/winsock_init.hpp>
 #include <boost/system/error_code.hpp>
 
@@ -44,6 +46,9 @@ namespace ip {
 class address_v4
 {
 public:
+  /// The type used to represent an address as an unsigned integer.
+  typedef uint_least32_t uint_type;
+
   /// The type used to represent an address as an array of bytes.
   /**
    * @note This type is defined in terms of the C++0x template @c std::array
@@ -64,8 +69,8 @@ class address_v4
   /// Construct an address from raw bytes.
   BOOST_ASIO_DECL explicit address_v4(const bytes_type& bytes);
 
-  /// Construct an address from a unsigned long in host byte order.
-  BOOST_ASIO_DECL explicit address_v4(unsigned long addr);
+  /// Construct an address from an unsigned integer in host byte order.
+  BOOST_ASIO_DECL explicit address_v4(uint_type addr);
 
   /// Copy constructor.
   address_v4(const address_v4& other)
@@ -100,28 +105,40 @@ class address_v4
   /// Get the address in bytes, in network byte order.
   BOOST_ASIO_DECL bytes_type to_bytes() const;
 
+  /// Get the address as an unsigned integer in host byte order
+  BOOST_ASIO_DECL uint_type to_uint() const;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   /// Get the address as an unsigned long in host byte order
   BOOST_ASIO_DECL unsigned long to_ulong() const;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Get the address as a string in dotted decimal format.
   BOOST_ASIO_DECL std::string to_string() const;
 
-  /// Get the address as a string in dotted decimal format.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use other overload.) Get the address as a string in dotted
+  /// decimal format.
   BOOST_ASIO_DECL std::string to_string(boost::system::error_code& ec) const;
 
-  /// Create an address from an IP address string in dotted decimal form.
-  BOOST_ASIO_DECL static address_v4 from_string(const char* str);
+  /// (Deprecated: Use make_address_v4().) Create an address from an IP address
+  /// string in dotted decimal form.
+  static address_v4 from_string(const char* str);
 
-  /// Create an address from an IP address string in dotted decimal form.
-  BOOST_ASIO_DECL static address_v4 from_string(
+  /// (Deprecated: Use make_address_v4().) Create an address from an IP address
+  /// string in dotted decimal form.
+  static address_v4 from_string(
       const char* str, boost::system::error_code& ec);
 
-  /// Create an address from an IP address string in dotted decimal form.
-  BOOST_ASIO_DECL static address_v4 from_string(const std::string& str);
+  /// (Deprecated: Use make_address_v4().) Create an address from an IP address
+  /// string in dotted decimal form.
+  static address_v4 from_string(const std::string& str);
 
-  /// Create an address from an IP address string in dotted decimal form.
-  BOOST_ASIO_DECL static address_v4 from_string(
+  /// (Deprecated: Use make_address_v4().) Create an address from an IP address
+  /// string in dotted decimal form.
+  static address_v4 from_string(
       const std::string& str, boost::system::error_code& ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Determine whether the address is a loopback address.
   BOOST_ASIO_DECL bool is_loopback() const;
@@ -129,14 +146,19 @@ class address_v4
   /// Determine whether the address is unspecified.
   BOOST_ASIO_DECL bool is_unspecified() const;
 
-  /// Determine whether the address is a class A address.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use network_v4 class.) Determine whether the address is a
+  /// class A address.
   BOOST_ASIO_DECL bool is_class_a() const;
 
-  /// Determine whether the address is a class B address.
+  /// (Deprecated: Use network_v4 class.) Determine whether the address is a
+  /// class B address.
   BOOST_ASIO_DECL bool is_class_b() const;
 
-  /// Determine whether the address is a class C address.
+  /// (Deprecated: Use network_v4 class.) Determine whether the address is a
+  /// class C address.
   BOOST_ASIO_DECL bool is_class_c() const;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Determine whether the address is a multicast address.
   BOOST_ASIO_DECL bool is_multicast() const;
@@ -156,25 +178,25 @@ class address_v4
   /// Compare addresses for ordering.
   friend bool operator<(const address_v4& a1, const address_v4& a2)
   {
-    return a1.to_ulong() < a2.to_ulong();
+    return a1.to_uint() < a2.to_uint();
   }
 
   /// Compare addresses for ordering.
   friend bool operator>(const address_v4& a1, const address_v4& a2)
   {
-    return a1.to_ulong() > a2.to_ulong();
+    return a1.to_uint() > a2.to_uint();
   }
 
   /// Compare addresses for ordering.
   friend bool operator<=(const address_v4& a1, const address_v4& a2)
   {
-    return a1.to_ulong() <= a2.to_ulong();
+    return a1.to_uint() <= a2.to_uint();
   }
 
   /// Compare addresses for ordering.
   friend bool operator>=(const address_v4& a1, const address_v4& a2)
   {
-    return a1.to_ulong() >= a2.to_ulong();
+    return a1.to_uint() >= a2.to_uint();
   }
 
   /// Obtain an address object that represents any address.
@@ -195,20 +217,86 @@ class address_v4
     return address_v4(0xFFFFFFFF);
   }
 
-  /// Obtain an address object that represents the broadcast address that
-  /// corresponds to the specified address and netmask.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use network_v4 class.) Obtain an address object that
+  /// represents the broadcast address that corresponds to the specified
+  /// address and netmask.
   BOOST_ASIO_DECL static address_v4 broadcast(
       const address_v4& addr, const address_v4& mask);
 
-  /// Obtain the netmask that corresponds to the address, based on its address
-  /// class.
+  /// (Deprecated: Use network_v4 class.) Obtain the netmask that corresponds
+  /// to the address, based on its address class.
   BOOST_ASIO_DECL static address_v4 netmask(const address_v4& addr);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 private:
   // The underlying IPv4 address.
   boost::asio::detail::in4_addr_type addr_;
 };
 
+/// Create an IPv4 address from raw bytes in network order.
+/**
+ * @relates address_v4
+ */
+inline address_v4 make_address_v4(const address_v4::bytes_type& bytes)
+{
+  return address_v4(bytes);
+}
+
+/// Create an IPv4 address from an unsigned integer in host byte order.
+/**
+ * @relates address_v4
+ */
+inline address_v4 make_address_v4(address_v4::uint_type addr)
+{
+  return address_v4(addr);
+}
+
+/// Create an IPv4 address from an IP address string in dotted decimal form.
+/**
+ * @relates address_v4
+ */
+BOOST_ASIO_DECL address_v4 make_address_v4(const char* str);
+
+/// Create an IPv4 address from an IP address string in dotted decimal form.
+/**
+ * @relates address_v4
+ */
+BOOST_ASIO_DECL address_v4 make_address_v4(
+    const char* str, boost::system::error_code& ec);
+
+/// Create an IPv4 address from an IP address string in dotted decimal form.
+/**
+ * @relates address_v4
+ */
+BOOST_ASIO_DECL address_v4 make_address_v4(const std::string& str);
+
+/// Create an IPv4 address from an IP address string in dotted decimal form.
+/**
+ * @relates address_v4
+ */
+BOOST_ASIO_DECL address_v4 make_address_v4(
+    const std::string& str, boost::system::error_code& ec);
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Create an IPv4 address from an IP address string in dotted decimal form.
+/**
+ * @relates address_v4
+ */
+BOOST_ASIO_DECL address_v4 make_address_v4(string_view str);
+
+/// Create an IPv4 address from an IP address string in dotted decimal form.
+/**
+ * @relates address_v4
+ */
+BOOST_ASIO_DECL address_v4 make_address_v4(
+    string_view str, boost::system::error_code& ec);
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+       //  || defined(GENERATING_DOCUMENTATION)
+
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Output an address as a string.
diff --git a/include/boost/asio/ip/address_v4_iterator.hpp b/include/boost/asio/ip/address_v4_iterator.hpp
new file mode 100644
index 0000000000..a2ccfc3748
--- /dev/null
+++ b/include/boost/asio/ip/address_v4_iterator.hpp
@@ -0,0 +1,164 @@
+//
+// ip/address_v4_iterator.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_ADDRESS_V4_ITERATOR_HPP
+#define BOOST_ASIO_IP_ADDRESS_V4_ITERATOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/ip/address_v4.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+template <typename> class basic_address_iterator;
+
+/// An input iterator that can be used for traversing IPv4 addresses.
+/**
+ * In addition to satisfying the input iterator requirements, this iterator
+ * also supports decrement.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+template <> class basic_address_iterator<address_v4>
+{
+public:
+  /// The type of the elements pointed to by the iterator.
+  typedef address_v4 value_type;
+
+  /// Distance between two iterators.
+  typedef std::ptrdiff_t difference_type;
+
+  /// The type of a pointer to an element pointed to by the iterator.
+  typedef const address_v4* pointer;
+
+  /// The type of a reference to an element pointed to by the iterator.
+  typedef const address_v4& reference;
+
+  /// Denotes that the iterator satisfies the input iterator requirements.
+  typedef std::input_iterator_tag iterator_category;
+
+  /// Construct an iterator that points to the specified address.
+  basic_address_iterator(const address_v4& addr) BOOST_ASIO_NOEXCEPT
+    : address_(addr)
+  {
+  }
+
+  /// Copy constructor.
+  basic_address_iterator(
+      const basic_address_iterator& other) BOOST_ASIO_NOEXCEPT
+    : address_(other.address_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move constructor.
+  basic_address_iterator(basic_address_iterator&& other) BOOST_ASIO_NOEXCEPT
+    : address_(BOOST_ASIO_MOVE_CAST(address_v4)(other.address_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Assignment operator.
+  basic_address_iterator& operator=(
+      const basic_address_iterator& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = other.address_;
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move assignment operator.
+  basic_address_iterator& operator=(
+      basic_address_iterator&& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = BOOST_ASIO_MOVE_CAST(address_v4)(other.address_);
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Dereference the iterator.
+  const address_v4& operator*() const BOOST_ASIO_NOEXCEPT
+  {
+    return address_;
+  }
+
+  /// Dereference the iterator.
+  const address_v4* operator->() const BOOST_ASIO_NOEXCEPT
+  {
+    return &address_;
+  }
+
+  /// Pre-increment operator.
+  basic_address_iterator& operator++() BOOST_ASIO_NOEXCEPT
+  {
+    address_ = address_v4((address_.to_uint() + 1) & 0xFFFFFFFF);
+    return *this;
+  }
+
+  /// Post-increment operator.
+  basic_address_iterator operator++(int) BOOST_ASIO_NOEXCEPT
+  {
+    basic_address_iterator tmp(*this);
+    ++*this;
+    return tmp;
+  }
+
+  /// Pre-decrement operator.
+  basic_address_iterator& operator--() BOOST_ASIO_NOEXCEPT
+  {
+    address_ = address_v4((address_.to_uint() - 1) & 0xFFFFFFFF);
+    return *this;
+  }
+
+  /// Post-decrement operator.
+  basic_address_iterator operator--(int)
+  {
+    basic_address_iterator tmp(*this);
+    --*this;
+    return tmp;
+  }
+
+  /// Compare two addresses for equality.
+  friend bool operator==(const basic_address_iterator& a,
+      const basic_address_iterator& b)
+  {
+    return a.address_ == b.address_;
+  }
+
+  /// Compare two addresses for inequality.
+  friend bool operator!=(const basic_address_iterator& a,
+      const basic_address_iterator& b)
+  {
+    return a.address_ != b.address_;
+  }
+
+private:
+  address_v4 address_;
+};
+
+/// An input iterator that can be used for traversing IPv4 addresses.
+typedef basic_address_iterator<address_v4> address_v4_iterator;
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_ADDRESS_V4_ITERATOR_HPP
diff --git a/include/boost/asio/ip/address_v4_range.hpp b/include/boost/asio/ip/address_v4_range.hpp
new file mode 100644
index 0000000000..1e2afeaf5a
--- /dev/null
+++ b/include/boost/asio/ip/address_v4_range.hpp
@@ -0,0 +1,136 @@
+//
+// ip/address_v4_range.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_ADDRESS_V4_RANGE_HPP
+#define BOOST_ASIO_IP_ADDRESS_V4_RANGE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/ip/address_v4_iterator.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+template <typename> class basic_address_range;
+
+/// Represents a range of IPv4 addresses.
+/**
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+template <> class basic_address_range<address_v4>
+{
+public:
+  /// The type of an iterator that points into the range.
+  typedef basic_address_iterator<address_v4> iterator;
+
+  /// Construct an empty range.
+  basic_address_range() BOOST_ASIO_NOEXCEPT
+    : begin_(address_v4()),
+      end_(address_v4())
+  {
+  }
+
+  /// Construct an range that represents the given range of addresses.
+  explicit basic_address_range(const iterator& first,
+      const iterator& last) BOOST_ASIO_NOEXCEPT
+    : begin_(first),
+      end_(last)
+  {
+  }
+
+  /// Copy constructor.
+  basic_address_range(const basic_address_range& other) BOOST_ASIO_NOEXCEPT
+    : begin_(other.begin_),
+      end_(other.end_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move constructor.
+  basic_address_range(basic_address_range&& other) BOOST_ASIO_NOEXCEPT
+    : begin_(BOOST_ASIO_MOVE_CAST(iterator)(other.begin_)),
+      end_(BOOST_ASIO_MOVE_CAST(iterator)(other.end_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Assignment operator.
+  basic_address_range& operator=(
+      const basic_address_range& other) BOOST_ASIO_NOEXCEPT
+  {
+    begin_ = other.begin_;
+    end_ = other.end_;
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move assignment operator.
+  basic_address_range& operator=(
+      basic_address_range&& other) BOOST_ASIO_NOEXCEPT
+  {
+    begin_ = BOOST_ASIO_MOVE_CAST(iterator)(other.begin_);
+    end_ = BOOST_ASIO_MOVE_CAST(iterator)(other.end_);
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Obtain an iterator that points to the start of the range.
+  iterator begin() const BOOST_ASIO_NOEXCEPT
+  {
+    return begin_;
+  }
+
+  /// Obtain an iterator that points to the end of the range.
+  iterator end() const BOOST_ASIO_NOEXCEPT
+  {
+    return end_;
+  }
+
+  /// Determine whether the range is empty.
+  bool empty() const BOOST_ASIO_NOEXCEPT
+  {
+    return size() == 0;
+  }
+
+  /// Return the size of the range.
+  std::size_t size() const BOOST_ASIO_NOEXCEPT
+  {
+    return end_->to_uint() - begin_->to_uint();
+  }
+
+  /// Find an address in the range.
+  iterator find(const address_v4& addr) const BOOST_ASIO_NOEXCEPT
+  {
+    return addr >= *begin_ && addr < *end_ ? iterator(addr) : end_;
+  }
+
+private:
+  iterator begin_;
+  iterator end_;
+};
+
+/// Represents a range of IPv4 addresses.
+typedef basic_address_range<address_v4> address_v4_range;
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_ADDRESS_V4_RANGE_HPP
diff --git a/include/boost/asio/ip/address_v6.hpp b/include/boost/asio/ip/address_v6.hpp
index 10e9bc1594..496a1df323 100644
--- a/include/boost/asio/ip/address_v6.hpp
+++ b/include/boost/asio/ip/address_v6.hpp
@@ -19,6 +19,7 @@
 #include <string>
 #include <boost/asio/detail/array.hpp>
 #include <boost/asio/detail/socket_types.hpp>
+#include <boost/asio/detail/string_view.hpp>
 #include <boost/asio/detail/winsock_init.hpp>
 #include <boost/system/error_code.hpp>
 #include <boost/asio/ip/address_v4.hpp>
@@ -33,6 +34,8 @@ namespace boost {
 namespace asio {
 namespace ip {
 
+template <typename> class basic_address_iterator;
+
 /// Implements IP version 6 style addresses.
 /**
  * The boost::asio::ip::address_v6 class provides the ability to use and
@@ -103,25 +106,32 @@ class address_v6
   /// Get the address as a string.
   BOOST_ASIO_DECL std::string to_string() const;
 
-  /// Get the address as a string.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use other overload.) Get the address as a string.
   BOOST_ASIO_DECL std::string to_string(boost::system::error_code& ec) const;
 
-  /// Create an address from an IP address string.
-  BOOST_ASIO_DECL static address_v6 from_string(const char* str);
+  /// (Deprecated: Use make_address_v6().) Create an IPv6 address from an IP
+  /// address string.
+  static address_v6 from_string(const char* str);
 
-  /// Create an address from an IP address string.
-  BOOST_ASIO_DECL static address_v6 from_string(
+  /// (Deprecated: Use make_address_v6().) Create an IPv6 address from an IP
+  /// address string.
+  static address_v6 from_string(
       const char* str, boost::system::error_code& ec);
 
-  /// Create an address from an IP address string.
-  BOOST_ASIO_DECL static address_v6 from_string(const std::string& str);
+  /// (Deprecated: Use make_address_v6().) Create an IPv6 address from an IP
+  /// address string.
+  static address_v6 from_string(const std::string& str);
 
-  /// Create an address from an IP address string.
-  BOOST_ASIO_DECL static address_v6 from_string(
+  /// (Deprecated: Use make_address_v6().) Create an IPv6 address from an IP
+  /// address string.
+  static address_v6 from_string(
       const std::string& str, boost::system::error_code& ec);
 
-  /// Converts an IPv4-mapped or IPv4-compatible address to an IPv4 address.
+  /// (Deprecated: Use make_address_v4().) Converts an IPv4-mapped or
+  /// IPv4-compatible address to an IPv4 address.
   BOOST_ASIO_DECL address_v4 to_v4() const;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Determine whether the address is a loopback address.
   BOOST_ASIO_DECL bool is_loopback() const;
@@ -138,8 +148,11 @@ class address_v6
   /// Determine whether the address is a mapped IPv4 address.
   BOOST_ASIO_DECL bool is_v4_mapped() const;
 
-  /// Determine whether the address is an IPv4-compatible address.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: No replacement.) Determine whether the address is an
+  /// IPv4-compatible address.
   BOOST_ASIO_DECL bool is_v4_compatible() const;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Determine whether the address is a multicast address.
   BOOST_ASIO_DECL bool is_multicast() const;
@@ -200,13 +213,17 @@ class address_v6
   /// Obtain an address object that represents the loopback address.
   BOOST_ASIO_DECL static address_v6 loopback();
 
-  /// Create an IPv4-mapped IPv6 address.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use make_address_v6().) Create an IPv4-mapped IPv6 address.
   BOOST_ASIO_DECL static address_v6 v4_mapped(const address_v4& addr);
 
-  /// Create an IPv4-compatible IPv6 address.
+  /// (Deprecated: No replacement.) Create an IPv4-compatible IPv6 address.
   BOOST_ASIO_DECL static address_v6 v4_compatible(const address_v4& addr);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 private:
+  friend class basic_address_iterator<address_v6>;
+
   // The underlying IPv6 address.
   boost::asio::detail::in6_addr_type addr_;
 
@@ -214,6 +231,79 @@ class address_v6
   unsigned long scope_id_;
 };
 
+/// Create an IPv6 address from raw bytes and scope ID.
+/**
+ * @relates address_v6
+ */
+inline address_v6 make_address_v6(const address_v6::bytes_type& bytes,
+    unsigned long scope_id = 0)
+{
+  return address_v6(bytes, scope_id);
+}
+
+/// Create an IPv6 address from an IP address string.
+/**
+ * @relates address_v6
+ */
+BOOST_ASIO_DECL address_v6 make_address_v6(const char* str);
+
+/// Create an IPv6 address from an IP address string.
+/**
+ * @relates address_v6
+ */
+BOOST_ASIO_DECL address_v6 make_address_v6(
+    const char* str, boost::system::error_code& ec);
+
+/// Createan IPv6 address from an IP address string.
+/**
+ * @relates address_v6
+ */
+BOOST_ASIO_DECL address_v6 make_address_v6(const std::string& str);
+
+/// Create an IPv6 address from an IP address string.
+/**
+ * @relates address_v6
+ */
+BOOST_ASIO_DECL address_v6 make_address_v6(
+    const std::string& str, boost::system::error_code& ec);
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Create an IPv6 address from an IP address string.
+/**
+ * @relates address_v6
+ */
+BOOST_ASIO_DECL address_v6 make_address_v6(string_view str);
+
+/// Create an IPv6 address from an IP address string.
+/**
+ * @relates address_v6
+ */
+BOOST_ASIO_DECL address_v6 make_address_v6(
+    string_view str, boost::system::error_code& ec);
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+       //  || defined(GENERATING_DOCUMENTATION)
+
+/// Tag type used for distinguishing overloads that deal in IPv4-mapped IPv6
+/// addresses.
+enum v4_mapped_t { v4_mapped };
+
+/// Create an IPv4 address from a IPv4-mapped IPv6 address.
+/**
+ * @relates address_v4
+ */
+BOOST_ASIO_DECL address_v4 make_address_v4(
+    v4_mapped_t, const address_v6& v6_addr);
+
+/// Create an IPv4-mapped IPv6 address from an IPv4 address.
+/**
+ * @relates address_v6
+ */
+BOOST_ASIO_DECL address_v6 make_address_v6(
+    v4_mapped_t, const address_v4& v4_addr);
+
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Output an address as a string.
diff --git a/include/boost/asio/ip/address_v6_iterator.hpp b/include/boost/asio/ip/address_v6_iterator.hpp
new file mode 100644
index 0000000000..4518996b3c
--- /dev/null
+++ b/include/boost/asio/ip/address_v6_iterator.hpp
@@ -0,0 +1,185 @@
+//
+// ip/address_v6_iterator.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//                         Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_ADDRESS_V6_ITERATOR_HPP
+#define BOOST_ASIO_IP_ADDRESS_V6_ITERATOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/ip/address_v6.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+template <typename> class basic_address_iterator;
+
+/// An input iterator that can be used for traversing IPv6 addresses.
+/**
+ * In addition to satisfying the input iterator requirements, this iterator
+ * also supports decrement.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+template <> class basic_address_iterator<address_v6>
+{
+public:
+  /// The type of the elements pointed to by the iterator.
+  typedef address_v6 value_type;
+
+  /// Distance between two iterators.
+  typedef std::ptrdiff_t difference_type;
+
+  /// The type of a pointer to an element pointed to by the iterator.
+  typedef const address_v6* pointer;
+
+  /// The type of a reference to an element pointed to by the iterator.
+  typedef const address_v6& reference;
+
+  /// Denotes that the iterator satisfies the input iterator requirements.
+  typedef std::input_iterator_tag iterator_category;
+
+  /// Construct an iterator that points to the specified address.
+  basic_address_iterator(const address_v6& addr) BOOST_ASIO_NOEXCEPT
+    : address_(addr)
+  {
+  }
+
+  /// Copy constructor.
+  basic_address_iterator(
+      const basic_address_iterator& other) BOOST_ASIO_NOEXCEPT
+    : address_(other.address_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move constructor.
+  basic_address_iterator(basic_address_iterator&& other) BOOST_ASIO_NOEXCEPT
+    : address_(BOOST_ASIO_MOVE_CAST(address_v6)(other.address_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Assignment operator.
+  basic_address_iterator& operator=(
+      const basic_address_iterator& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = other.address_;
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move assignment operator.
+  basic_address_iterator& operator=(
+      basic_address_iterator&& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = BOOST_ASIO_MOVE_CAST(address_v6)(other.address_);
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Dereference the iterator.
+  const address_v6& operator*() const BOOST_ASIO_NOEXCEPT
+  {
+    return address_;
+  }
+
+  /// Dereference the iterator.
+  const address_v6* operator->() const BOOST_ASIO_NOEXCEPT
+  {
+    return &address_;
+  }
+
+  /// Pre-increment operator.
+  basic_address_iterator& operator++() BOOST_ASIO_NOEXCEPT
+  {
+    for (int i = 15; i >= 0; --i)
+    {
+      if (address_.addr_.s6_addr[i] < 0xFF)
+      {
+        ++address_.addr_.s6_addr[i];
+        break;
+      }
+
+      address_.addr_.s6_addr[i] = 0;
+    }
+
+    return *this;
+  }
+
+  /// Post-increment operator.
+  basic_address_iterator operator++(int) BOOST_ASIO_NOEXCEPT
+  {
+    basic_address_iterator tmp(*this);
+    ++*this;
+    return tmp;
+  }
+
+  /// Pre-decrement operator.
+  basic_address_iterator& operator--() BOOST_ASIO_NOEXCEPT
+  {
+    for (int i = 15; i >= 0; --i)
+    {
+      if (address_.addr_.s6_addr[i] > 0)
+      {
+        --address_.addr_.s6_addr[i];
+        break;
+      }
+
+      address_.addr_.s6_addr[i] = 0xFF;
+    }
+
+    return *this;
+  }
+
+  /// Post-decrement operator.
+  basic_address_iterator operator--(int)
+  {
+    basic_address_iterator tmp(*this);
+    --*this;
+    return tmp;
+  }
+
+  /// Compare two addresses for equality.
+  friend bool operator==(const basic_address_iterator& a,
+      const basic_address_iterator& b)
+  {
+    return a.address_ == b.address_;
+  }
+
+  /// Compare two addresses for inequality.
+  friend bool operator!=(const basic_address_iterator& a,
+      const basic_address_iterator& b)
+  {
+    return a.address_ != b.address_;
+  }
+
+private:
+  address_v6 address_;
+};
+
+/// An input iterator that can be used for traversing IPv6 addresses.
+typedef basic_address_iterator<address_v6> address_v6_iterator;
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_ADDRESS_V6_ITERATOR_HPP
diff --git a/include/boost/asio/ip/address_v6_range.hpp b/include/boost/asio/ip/address_v6_range.hpp
new file mode 100644
index 0000000000..68b987d7c9
--- /dev/null
+++ b/include/boost/asio/ip/address_v6_range.hpp
@@ -0,0 +1,131 @@
+//
+// ip/address_v6_range.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//                         Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_ADDRESS_V6_RANGE_HPP
+#define BOOST_ASIO_IP_ADDRESS_V6_RANGE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/ip/address_v6_iterator.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+template <typename> class basic_address_range;
+
+/// Represents a range of IPv6 addresses.
+/**
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+template <> class basic_address_range<address_v6>
+{
+public:
+  /// The type of an iterator that points into the range.
+  typedef basic_address_iterator<address_v6> iterator;
+
+  /// Construct an empty range.
+  basic_address_range() BOOST_ASIO_NOEXCEPT
+    : begin_(address_v6()),
+      end_(address_v6())
+  {
+  }
+
+  /// Construct an range that represents the given range of addresses.
+  explicit basic_address_range(const iterator& first,
+      const iterator& last) BOOST_ASIO_NOEXCEPT
+    : begin_(first),
+      end_(last)
+  {
+  }
+
+  /// Copy constructor.
+  basic_address_range(const basic_address_range& other) BOOST_ASIO_NOEXCEPT
+    : begin_(other.begin_),
+      end_(other.end_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move constructor.
+  basic_address_range(basic_address_range&& other) BOOST_ASIO_NOEXCEPT
+    : begin_(BOOST_ASIO_MOVE_CAST(iterator)(other.begin_)),
+      end_(BOOST_ASIO_MOVE_CAST(iterator)(other.end_))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Assignment operator.
+  basic_address_range& operator=(
+      const basic_address_range& other) BOOST_ASIO_NOEXCEPT
+  {
+    begin_ = other.begin_;
+    end_ = other.end_;
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move assignment operator.
+  basic_address_range& operator=(
+      basic_address_range&& other) BOOST_ASIO_NOEXCEPT
+  {
+    begin_ = BOOST_ASIO_MOVE_CAST(iterator)(other.begin_);
+    end_ = BOOST_ASIO_MOVE_CAST(iterator)(other.end_);
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Obtain an iterator that points to the start of the range.
+  iterator begin() const BOOST_ASIO_NOEXCEPT
+  {
+    return begin_;
+  }
+
+  /// Obtain an iterator that points to the end of the range.
+  iterator end() const BOOST_ASIO_NOEXCEPT
+  {
+    return end_;
+  }
+
+  /// Determine whether the range is empty.
+  bool empty() const BOOST_ASIO_NOEXCEPT
+  {
+    return begin_ == end_;
+  }
+
+  /// Find an address in the range.
+  iterator find(const address_v6& addr) const BOOST_ASIO_NOEXCEPT
+  {
+    return addr >= *begin_ && addr < *end_ ? iterator(addr) : end_;
+  }
+
+private:
+  iterator begin_;
+  iterator end_;
+};
+
+/// Represents a range of IPv6 addresses.
+typedef basic_address_range<address_v6> address_v6_range;
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_ADDRESS_V6_RANGE_HPP
diff --git a/include/boost/asio/ip/bad_address_cast.hpp b/include/boost/asio/ip/bad_address_cast.hpp
new file mode 100644
index 0000000000..9c82fdfeb3
--- /dev/null
+++ b/include/boost/asio/ip/bad_address_cast.hpp
@@ -0,0 +1,50 @@
+//
+// ip/bad_address_cast.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_BAD_ADDRESS_CAST_HPP
+#define BOOST_ASIO_IP_BAD_ADDRESS_CAST_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <typeinfo>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+/// Thrown to indicate a failed address conversion.
+class bad_address_cast : public std::bad_cast
+{
+public:
+  /// Default constructor.
+  bad_address_cast() {}
+
+  /// Destructor.
+  virtual ~bad_address_cast() BOOST_ASIO_NOEXCEPT_OR_NOTHROW {}
+
+  /// Get the message associated with the exception.
+  virtual const char* what() const BOOST_ASIO_NOEXCEPT_OR_NOTHROW
+  {
+    return "bad address cast";
+  }
+};
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_ADDRESS_HPP
diff --git a/include/boost/asio/ip/basic_endpoint.hpp b/include/boost/asio/ip/basic_endpoint.hpp
index 235b178589..7a9f72ba36 100644
--- a/include/boost/asio/ip/basic_endpoint.hpp
+++ b/include/boost/asio/ip/basic_endpoint.hpp
@@ -98,13 +98,13 @@ class basic_endpoint
   {
   }
 
-#if defined(BOOST_ASIO_HAS_MOVE)
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
   /// Move constructor.
   basic_endpoint(basic_endpoint&& other)
     : impl_(other.impl_)
   {
   }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
   /// Assign from another endpoint.
   basic_endpoint& operator=(const basic_endpoint& other)
@@ -113,14 +113,14 @@ class basic_endpoint
     return *this;
   }
 
-#if defined(BOOST_ASIO_HAS_MOVE)
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
   /// Move-assign from another endpoint.
   basic_endpoint& operator=(basic_endpoint&& other)
   {
     impl_ = other.impl_;
     return *this;
   }
-#endif // defined(BOOST_ASIO_HAS_MOVE)
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
   /// The protocol associated with the endpoint.
   protocol_type protocol() const
diff --git a/include/boost/asio/ip/basic_resolver.hpp b/include/boost/asio/ip/basic_resolver.hpp
index c5941de4f1..714e950832 100644
--- a/include/boost/asio/ip/basic_resolver.hpp
+++ b/include/boost/asio/ip/basic_resolver.hpp
@@ -16,13 +16,36 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <string>
+#include <boost/asio/async_result.hpp>
 #include <boost/asio/basic_io_object.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/string_view.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/basic_resolver_iterator.hpp>
 #include <boost/asio/ip/basic_resolver_query.hpp>
-#include <boost/asio/ip/resolver_service.hpp>
+#include <boost/asio/ip/basic_resolver_results.hpp>
+#include <boost/asio/ip/resolver_base.hpp>
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/ip/resolver_service.hpp>
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#  include <boost/asio/detail/winrt_resolver_service.hpp>
+#  define BOOST_ASIO_SVC_T \
+    boost::asio::detail::winrt_resolver_service<InternetProtocol>
+# else
+#  include <boost/asio/detail/resolver_service.hpp>
+#  define BOOST_ASIO_SVC_T \
+    boost::asio::detail::resolver_service<InternetProtocol>
+# endif
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -39,35 +62,130 @@ namespace ip {
  * @e Distinct @e objects: Safe.@n
  * @e Shared @e objects: Unsafe.
  */
-template <typename InternetProtocol,
-    typename ResolverService = resolver_service<InternetProtocol> >
+template <typename InternetProtocol
+    BOOST_ASIO_SVC_TPARAM_DEF1(= resolver_service<InternetProtocol>)>
 class basic_resolver
-  : public basic_io_object<ResolverService>
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>,
+    public resolver_base
 {
 public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
   /// The protocol type.
   typedef InternetProtocol protocol_type;
 
   /// The endpoint type.
   typedef typename InternetProtocol::endpoint endpoint_type;
 
-  /// The query type.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated.) The query type.
   typedef basic_resolver_query<InternetProtocol> query;
 
-  /// The iterator type.
+  /// (Deprecated.) The iterator type.
   typedef basic_resolver_iterator<InternetProtocol> iterator;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// The results type.
+  typedef basic_resolver_results<InternetProtocol> results_type;
 
   /// Constructor.
   /**
    * This constructor creates a basic_resolver.
    *
-   * @param io_service The io_service object that the resolver will use to
-   * dispatch handlers for any asynchronous operations performed on the timer.
+   * @param io_context The io_context object that the resolver will use to
+   * dispatch handlers for any asynchronous operations performed on the
+   * resolver.
+   */
+  explicit basic_resolver(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a basic_resolver from another.
+  /**
+   * This constructor moves a resolver from one object to another.
+   *
+   * @param other The other basic_resolver object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c basic_resolver(io_context&) constructor.
+   */
+  basic_resolver(basic_resolver&& other)
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
+  {
+  }
+
+  /// Move-assign a basic_resolver from another.
+  /**
+   * This assignment operator moves a resolver from one object to another.
+   * Cancels any outstanding asynchronous operations associated with the target
+   * object.
+   *
+   * @param other The other basic_resolver object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c basic_resolver(io_context&) constructor.
+   */
+  basic_resolver& operator=(basic_resolver&& other)
+  {
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Destroys the resolver.
+  /**
+   * This function destroys the resolver, cancelling any outstanding
+   * asynchronous wait operations associated with the resolver as if by calling
+   * @c cancel.
+   */
+  ~basic_resolver()
+  {
+  }
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  // These functions are provided by basic_io_object<>.
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
    */
-  explicit basic_resolver(boost::asio::io_service& io_service)
-    : basic_io_object<ResolverService>(io_service)
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
   {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
   }
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
   /// Cancel any asynchronous operations that are waiting on the resolver.
   /**
@@ -77,56 +195,414 @@ class basic_resolver
    */
   void cancel()
   {
-    return this->service.cancel(this->implementation);
+    return this->get_service().cancel(this->get_implementation());
   }
 
-  /// Perform forward resolution of a query to a list of entries.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated.) Perform forward resolution of a query to a list of entries.
   /**
    * This function is used to resolve a query into a list of endpoint entries.
    *
    * @param q A query object that determines what endpoints will be returned.
    *
-   * @returns A forward-only iterator that can be used to traverse the list
-   * of endpoint entries.
+   * @returns A range object representing the list of endpoint entries. A
+   * successful call to this function is guaranteed to return a non-empty
+   * range.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  results_type resolve(const query& q)
+  {
+    boost::system::error_code ec;
+    results_type r = this->get_service().resolve(
+        this->get_implementation(), q, ec);
+    boost::asio::detail::throw_error(ec, "resolve");
+    return r;
+  }
+
+  /// (Deprecated.) Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve a query into a list of endpoint entries.
+   *
+   * @param q A query object that determines what endpoints will be returned.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns A range object representing the list of endpoint entries. An
+   * empty range is returned if an error occurs. A successful call to this
+   * function is guaranteed to return a non-empty range.
+   */
+  results_type resolve(const query& q, boost::system::error_code& ec)
+  {
+    return this->get_service().resolve(this->get_implementation(), q, ec);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @returns A range object representing the list of endpoint entries. A
+   * successful call to this function is guaranteed to return a non-empty
+   * range.
    *
    * @throws boost::system::system_error Thrown on failure.
    *
-   * @note A default constructed iterator represents the end of the list.
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
    *
-   * A successful call to this function is guaranteed to return at least one
-   * entry.
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
    */
-  iterator resolve(const query& q)
+  results_type resolve(BOOST_ASIO_STRING_VIEW_PARAM host,
+      BOOST_ASIO_STRING_VIEW_PARAM service)
+  {
+    return resolve(host, service, resolver_base::flags());
+  }
+
+  /// Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns A range object representing the list of endpoint entries. An
+   * empty range is returned if an error occurs. A successful call to this
+   * function is guaranteed to return a non-empty range.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  results_type resolve(BOOST_ASIO_STRING_VIEW_PARAM host,
+      BOOST_ASIO_STRING_VIEW_PARAM service, boost::system::error_code& ec)
+  {
+    return resolve(host, service, resolver_base::flags(), ec);
+  }
+
+  /// Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param resolve_flags A set of flags that determine how name resolution
+   * should be performed. The default flags are suitable for communication with
+   * remote hosts.
+   *
+   * @returns A range object representing the list of endpoint entries. A
+   * successful call to this function is guaranteed to return a non-empty
+   * range.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  results_type resolve(BOOST_ASIO_STRING_VIEW_PARAM host,
+      BOOST_ASIO_STRING_VIEW_PARAM service, resolver_base::flags resolve_flags)
   {
     boost::system::error_code ec;
-    iterator i = this->service.resolve(this->implementation, q, ec);
+    basic_resolver_query<protocol_type> q(static_cast<std::string>(host),
+        static_cast<std::string>(service), resolve_flags);
+    results_type r = this->get_service().resolve(
+        this->get_implementation(), q, ec);
     boost::asio::detail::throw_error(ec, "resolve");
-    return i;
+    return r;
   }
 
   /// Perform forward resolution of a query to a list of entries.
   /**
-   * This function is used to resolve a query into a list of endpoint entries.
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
    *
-   * @param q A query object that determines what endpoints will be returned.
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param resolve_flags A set of flags that determine how name resolution
+   * should be performed. The default flags are suitable for communication with
+   * remote hosts.
    *
    * @param ec Set to indicate what error occurred, if any.
    *
-   * @returns A forward-only iterator that can be used to traverse the list
-   * of endpoint entries. Returns a default constructed iterator if an error
-   * occurs.
+   * @returns A range object representing the list of endpoint entries. An
+   * empty range is returned if an error occurs. A successful call to this
+   * function is guaranteed to return a non-empty range.
    *
-   * @note A default constructed iterator represents the end of the list.
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
    *
-   * A successful call to this function is guaranteed to return at least one
-   * entry.
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
    */
-  iterator resolve(const query& q, boost::system::error_code& ec)
+  results_type resolve(BOOST_ASIO_STRING_VIEW_PARAM host,
+      BOOST_ASIO_STRING_VIEW_PARAM service, resolver_base::flags resolve_flags,
+      boost::system::error_code& ec)
   {
-    return this->service.resolve(this->implementation, q, ec);
+    basic_resolver_query<protocol_type> q(static_cast<std::string>(host),
+        static_cast<std::string>(service), resolve_flags);
+    return this->get_service().resolve(this->get_implementation(), q, ec);
   }
 
-  /// Asynchronously perform forward resolution of a query to a list of entries.
+  /// Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param protocol A protocol object, normally representing either the IPv4 or
+   * IPv6 version of an internet protocol.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @returns A range object representing the list of endpoint entries. A
+   * successful call to this function is guaranteed to return a non-empty
+   * range.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  results_type resolve(const protocol_type& protocol,
+      BOOST_ASIO_STRING_VIEW_PARAM host, BOOST_ASIO_STRING_VIEW_PARAM service)
+  {
+    return resolve(protocol, host, service, resolver_base::flags());
+  }
+
+  /// Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param protocol A protocol object, normally representing either the IPv4 or
+   * IPv6 version of an internet protocol.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns A range object representing the list of endpoint entries. An
+   * empty range is returned if an error occurs. A successful call to this
+   * function is guaranteed to return a non-empty range.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  results_type resolve(const protocol_type& protocol,
+      BOOST_ASIO_STRING_VIEW_PARAM host, BOOST_ASIO_STRING_VIEW_PARAM service,
+      boost::system::error_code& ec)
+  {
+    return resolve(protocol, host, service, resolver_base::flags(), ec);
+  }
+
+  /// Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param protocol A protocol object, normally representing either the IPv4 or
+   * IPv6 version of an internet protocol.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param resolve_flags A set of flags that determine how name resolution
+   * should be performed. The default flags are suitable for communication with
+   * remote hosts.
+   *
+   * @returns A range object representing the list of endpoint entries. A
+   * successful call to this function is guaranteed to return a non-empty
+   * range.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  results_type resolve(const protocol_type& protocol,
+      BOOST_ASIO_STRING_VIEW_PARAM host, BOOST_ASIO_STRING_VIEW_PARAM service,
+      resolver_base::flags resolve_flags)
+  {
+    boost::system::error_code ec;
+    basic_resolver_query<protocol_type> q(
+        protocol, static_cast<std::string>(host),
+        static_cast<std::string>(service), resolve_flags);
+    results_type r = this->get_service().resolve(
+        this->get_implementation(), q, ec);
+    boost::asio::detail::throw_error(ec, "resolve");
+    return r;
+  }
+
+  /// Perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param protocol A protocol object, normally representing either the IPv4 or
+   * IPv6 version of an internet protocol.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param resolve_flags A set of flags that determine how name resolution
+   * should be performed. The default flags are suitable for communication with
+   * remote hosts.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns A range object representing the list of endpoint entries. An
+   * empty range is returned if an error occurs. A successful call to this
+   * function is guaranteed to return a non-empty range.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  results_type resolve(const protocol_type& protocol,
+      BOOST_ASIO_STRING_VIEW_PARAM host, BOOST_ASIO_STRING_VIEW_PARAM service,
+      resolver_base::flags resolve_flags, boost::system::error_code& ec)
+  {
+    basic_resolver_query<protocol_type> q(
+        protocol, static_cast<std::string>(host),
+        static_cast<std::string>(service), resolve_flags);
+    return this->get_service().resolve(this->get_implementation(), q, ec);
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated.) Asynchronously perform forward resolution of a query to a
+  /// list of entries.
   /**
    * This function is used to asynchronously resolve a query into a list of
    * endpoint entries.
@@ -138,35 +614,307 @@ class basic_resolver
    * signature of the handler must be:
    * @code void handler(
    *   const boost::system::error_code& error, // Result of operation.
-   *   resolver::iterator iterator             // Forward-only iterator that can
-   *                                           // be used to traverse the list
-   *                                           // of endpoint entries.
+   *   resolver::results_type results // Resolved endpoints as a range.
    * ); @endcode
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
-   * @note A default constructed iterator represents the end of the list.
-   *
-   * A successful resolve operation is guaranteed to pass at least one entry to
+   * A successful resolve operation is guaranteed to pass a non-empty range to
    * the handler.
    */
   template <typename ResolveHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
-      void (boost::system::error_code, iterator))
+      void (boost::system::error_code, results_type))
   async_resolve(const query& q,
       BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
   {
     // If you get an error on the following line it means that your handler does
     // not meet the documented type requirements for a ResolveHandler.
     BOOST_ASIO_RESOLVE_HANDLER_CHECK(
-        ResolveHandler, handler, iterator) type_check;
+        ResolveHandler, handler, results_type) type_check;
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_resolve(this->get_implementation(), q,
+        BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    boost::asio::async_completion<ResolveHandler,
+      void (boost::system::error_code, results_type)> init(handler);
+
+    this->get_service().async_resolve(
+        this->get_implementation(), q, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Asynchronously perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param handler The handler to be called when the resolve operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   resolver::results_type results // Resolved endpoints as a range.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * A successful resolve operation is guaranteed to pass a non-empty range to
+   * the handler.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  template <typename ResolveHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
+      void (boost::system::error_code, results_type))
+  async_resolve(BOOST_ASIO_STRING_VIEW_PARAM host,
+      BOOST_ASIO_STRING_VIEW_PARAM service,
+      BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
+  {
+    return async_resolve(host, service, resolver_base::flags(),
+        BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
+  }
+
+  /// Asynchronously perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param resolve_flags A set of flags that determine how name resolution
+   * should be performed. The default flags are suitable for communication with
+   * remote hosts.
+   *
+   * @param handler The handler to be called when the resolve operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   resolver::results_type results // Resolved endpoints as a range.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * A successful resolve operation is guaranteed to pass a non-empty range to
+   * the handler.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  template <typename ResolveHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
+      void (boost::system::error_code, results_type))
+  async_resolve(BOOST_ASIO_STRING_VIEW_PARAM host,
+      BOOST_ASIO_STRING_VIEW_PARAM service,
+      resolver_base::flags resolve_flags,
+      BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a ResolveHandler.
+    BOOST_ASIO_RESOLVE_HANDLER_CHECK(
+        ResolveHandler, handler, results_type) type_check;
 
-    return this->service.async_resolve(this->implementation, q,
+    basic_resolver_query<protocol_type> q(static_cast<std::string>(host),
+        static_cast<std::string>(service), resolve_flags);
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_resolve(this->get_implementation(), q,
+        BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    boost::asio::async_completion<ResolveHandler,
+      void (boost::system::error_code, results_type)> init(handler);
+
+    this->get_service().async_resolve(
+        this->get_implementation(), q, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+
+  /// Asynchronously perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param protocol A protocol object, normally representing either the IPv4 or
+   * IPv6 version of an internet protocol.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param handler The handler to be called when the resolve operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   resolver::results_type results // Resolved endpoints as a range.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * A successful resolve operation is guaranteed to pass a non-empty range to
+   * the handler.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  template <typename ResolveHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
+      void (boost::system::error_code, results_type))
+  async_resolve(const protocol_type& protocol,
+      BOOST_ASIO_STRING_VIEW_PARAM host, BOOST_ASIO_STRING_VIEW_PARAM service,
+      BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
+  {
+    return async_resolve(protocol, host, service, resolver_base::flags(),
         BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
   }
 
+  /// Asynchronously perform forward resolution of a query to a list of entries.
+  /**
+   * This function is used to resolve host and service names into a list of
+   * endpoint entries.
+   *
+   * @param protocol A protocol object, normally representing either the IPv4 or
+   * IPv6 version of an internet protocol.
+   *
+   * @param host A string identifying a location. May be a descriptive name or
+   * a numeric address string. If an empty string and the passive flag has been
+   * specified, the resolved endpoints are suitable for local service binding.
+   * If an empty string and passive is not specified, the resolved endpoints
+   * will use the loopback address.
+   *
+   * @param service A string identifying the requested service. This may be a
+   * descriptive name or a numeric string corresponding to a port number. May
+   * be an empty string, in which case all resolved endpoints will have a port
+   * number of 0.
+   *
+   * @param resolve_flags A set of flags that determine how name resolution
+   * should be performed. The default flags are suitable for communication with
+   * remote hosts.
+   *
+   * @param handler The handler to be called when the resolve operation
+   * completes. Copies will be made of the handler as required. The function
+   * signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   resolver::results_type results // Resolved endpoints as a range.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * A successful resolve operation is guaranteed to pass a non-empty range to
+   * the handler.
+   *
+   * @note On POSIX systems, host names may be locally defined in the file
+   * <tt>/etc/hosts</tt>. On Windows, host names may be defined in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\hosts</tt>. Remote host name
+   * resolution is performed using DNS. Operating systems may use additional
+   * locations when resolving host names (such as NETBIOS names on Windows).
+   *
+   * On POSIX systems, service names are typically defined in the file
+   * <tt>/etc/services</tt>. On Windows, service names may be found in the file
+   * <tt>c:\\windows\\system32\\drivers\\etc\\services</tt>. Operating systems
+   * may use additional locations when resolving service names.
+   */
+  template <typename ResolveHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
+      void (boost::system::error_code, results_type))
+  async_resolve(const protocol_type& protocol,
+      BOOST_ASIO_STRING_VIEW_PARAM host, BOOST_ASIO_STRING_VIEW_PARAM service,
+      resolver_base::flags resolve_flags,
+      BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a ResolveHandler.
+    BOOST_ASIO_RESOLVE_HANDLER_CHECK(
+        ResolveHandler, handler, results_type) type_check;
+
+    basic_resolver_query<protocol_type> q(
+        protocol, static_cast<std::string>(host),
+        static_cast<std::string>(service), resolve_flags);
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_resolve(this->get_implementation(), q,
+        BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    boost::asio::async_completion<ResolveHandler,
+      void (boost::system::error_code, results_type)> init(handler);
+
+    this->get_service().async_resolve(
+        this->get_implementation(), q, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  }
+
   /// Perform reverse resolution of an endpoint to a list of entries.
   /**
    * This function is used to resolve an endpoint into a list of endpoint
@@ -175,20 +923,17 @@ class basic_resolver
    * @param e An endpoint object that determines what endpoints will be
    * returned.
    *
-   * @returns A forward-only iterator that can be used to traverse the list
-   * of endpoint entries.
+   * @returns A range object representing the list of endpoint entries. A
+   * successful call to this function is guaranteed to return a non-empty
+   * range.
    *
    * @throws boost::system::system_error Thrown on failure.
-   *
-   * @note A default constructed iterator represents the end of the list.
-   *
-   * A successful call to this function is guaranteed to return at least one
-   * entry.
    */
-  iterator resolve(const endpoint_type& e)
+  results_type resolve(const endpoint_type& e)
   {
     boost::system::error_code ec;
-    iterator i = this->service.resolve(this->implementation, e, ec);
+    results_type i = this->get_service().resolve(
+        this->get_implementation(), e, ec);
     boost::asio::detail::throw_error(ec, "resolve");
     return i;
   }
@@ -203,18 +948,13 @@ class basic_resolver
    *
    * @param ec Set to indicate what error occurred, if any.
    *
-   * @returns A forward-only iterator that can be used to traverse the list
-   * of endpoint entries. Returns a default constructed iterator if an error
-   * occurs.
-   *
-   * @note A default constructed iterator represents the end of the list.
-   *
-   * A successful call to this function is guaranteed to return at least one
-   * entry.
+   * @returns A range object representing the list of endpoint entries. An
+   * empty range is returned if an error occurs. A successful call to this
+   * function is guaranteed to return a non-empty range.
    */
-  iterator resolve(const endpoint_type& e, boost::system::error_code& ec)
+  results_type resolve(const endpoint_type& e, boost::system::error_code& ec)
   {
-    return this->service.resolve(this->implementation, e, ec);
+    return this->get_service().resolve(this->get_implementation(), e, ec);
   }
 
   /// Asynchronously perform reverse resolution of an endpoint to a list of
@@ -231,33 +971,39 @@ class basic_resolver
    * signature of the handler must be:
    * @code void handler(
    *   const boost::system::error_code& error, // Result of operation.
-   *   resolver::iterator iterator             // Forward-only iterator that can
-   *                                           // be used to traverse the list
-   *                                           // of endpoint entries.
+   *   resolver::results_type results // Resolved endpoints as a range.
    * ); @endcode
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
-   * @note A default constructed iterator represents the end of the list.
-   *
-   * A successful resolve operation is guaranteed to pass at least one entry to
+   * A successful resolve operation is guaranteed to pass a non-empty range to
    * the handler.
    */
   template <typename ResolveHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
-      void (boost::system::error_code, iterator))
+      void (boost::system::error_code, results_type))
   async_resolve(const endpoint_type& e,
       BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
   {
     // If you get an error on the following line it means that your handler does
     // not meet the documented type requirements for a ResolveHandler.
     BOOST_ASIO_RESOLVE_HANDLER_CHECK(
-        ResolveHandler, handler, iterator) type_check;
+        ResolveHandler, handler, results_type) type_check;
 
-    return this->service.async_resolve(this->implementation, e,
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    return this->get_service().async_resolve(this->get_implementation(), e,
         BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+    boost::asio::async_completion<ResolveHandler,
+      void (boost::system::error_code, results_type)> init(handler);
+
+    this->get_service().async_resolve(
+        this->get_implementation(), e, init.completion_handler);
+
+    return init.result.get();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
   }
 };
 
@@ -267,4 +1013,8 @@ class basic_resolver
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# undef BOOST_ASIO_SVC_T
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_IP_BASIC_RESOLVER_HPP
diff --git a/include/boost/asio/ip/basic_resolver_entry.hpp b/include/boost/asio/ip/basic_resolver_entry.hpp
index 05c8547a0c..ec6c7bd6d5 100644
--- a/include/boost/asio/ip/basic_resolver_entry.hpp
+++ b/include/boost/asio/ip/basic_resolver_entry.hpp
@@ -17,6 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <string>
+#include <boost/asio/detail/string_view.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -50,10 +51,10 @@ class basic_resolver_entry
 
   /// Construct with specified endpoint, host name and service name.
   basic_resolver_entry(const endpoint_type& ep,
-      const std::string& host, const std::string& service)
+      BOOST_ASIO_STRING_VIEW_PARAM host, BOOST_ASIO_STRING_VIEW_PARAM service)
     : endpoint_(ep),
-      host_name_(host),
-      service_name_(service)
+      host_name_(static_cast<std::string>(host)),
+      service_name_(static_cast<std::string>(service))
   {
   }
 
@@ -75,12 +76,30 @@ class basic_resolver_entry
     return host_name_;
   }
 
+  /// Get the host name associated with the entry.
+  template <class Allocator>
+  std::basic_string<char, std::char_traits<char>, Allocator> host_name(
+      const Allocator& alloc = Allocator()) const
+  {
+    return std::basic_string<char, std::char_traits<char>, Allocator>(
+        host_name_.c_str(), alloc);
+  }
+
   /// Get the service name associated with the entry.
   std::string service_name() const
   {
     return service_name_;
   }
 
+  /// Get the service name associated with the entry.
+  template <class Allocator>
+  std::basic_string<char, std::char_traits<char>, Allocator> service_name(
+      const Allocator& alloc = Allocator()) const
+  {
+    return std::basic_string<char, std::char_traits<char>, Allocator>(
+        service_name_.c_str(), alloc);
+  }
+
 private:
   endpoint_type endpoint_;
   std::string host_name_;
diff --git a/include/boost/asio/ip/basic_resolver_iterator.hpp b/include/boost/asio/ip/basic_resolver_iterator.hpp
index b7deb77364..6571fdd982 100644
--- a/include/boost/asio/ip/basic_resolver_iterator.hpp
+++ b/include/boost/asio/ip/basic_resolver_iterator.hpp
@@ -21,7 +21,7 @@
 #include <iterator>
 #include <string>
 #include <vector>
-#include <boost/asio/detail/shared_ptr.hpp>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
 #include <boost/asio/detail/socket_types.hpp>
 #include <boost/asio/ip/basic_resolver_entry.hpp>
@@ -73,114 +73,45 @@ class basic_resolver_iterator
   {
   }
 
-  /// Create an iterator from an addrinfo list returned by getaddrinfo.
-  static basic_resolver_iterator create(
-      boost::asio::detail::addrinfo_type* address_info,
-      const std::string& host_name, const std::string& service_name)
+  /// Copy constructor.
+  basic_resolver_iterator(const basic_resolver_iterator& other)
+    : values_(other.values_),
+      index_(other.index_)
   {
-    basic_resolver_iterator iter;
-    if (!address_info)
-      return iter;
-
-    std::string actual_host_name = host_name;
-    if (address_info->ai_canonname)
-      actual_host_name = address_info->ai_canonname;
-
-    iter.values_.reset(new values_type);
-
-    while (address_info)
-    {
-      if (address_info->ai_family == BOOST_ASIO_OS_DEF(AF_INET)
-          || address_info->ai_family == BOOST_ASIO_OS_DEF(AF_INET6))
-      {
-        using namespace std; // For memcpy.
-        typename InternetProtocol::endpoint endpoint;
-        endpoint.resize(static_cast<std::size_t>(address_info->ai_addrlen));
-        memcpy(endpoint.data(), address_info->ai_addr,
-            address_info->ai_addrlen);
-        iter.values_->push_back(
-            basic_resolver_entry<InternetProtocol>(endpoint,
-              actual_host_name, service_name));
-      }
-      address_info = address_info->ai_next;
-    }
-
-    return iter;
   }
 
-  /// Create an iterator from an endpoint, host name and service name.
-  static basic_resolver_iterator create(
-      const typename InternetProtocol::endpoint& endpoint,
-      const std::string& host_name, const std::string& service_name)
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move constructor.
+  basic_resolver_iterator(basic_resolver_iterator&& other)
+    : values_(BOOST_ASIO_MOVE_CAST(values_ptr_type)(other.values_)),
+      index_(other.index_)
   {
-    basic_resolver_iterator iter;
-    iter.values_.reset(new values_type);
-    iter.values_->push_back(
-        basic_resolver_entry<InternetProtocol>(
-          endpoint, host_name, service_name));
-    return iter;
+    other.index_ = 0;
   }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
-  /// Create an iterator from a sequence of endpoints, host and service name.
-  template <typename EndpointIterator>
-  static basic_resolver_iterator create(
-      EndpointIterator begin, EndpointIterator end,
-      const std::string& host_name, const std::string& service_name)
+  /// Assignment operator.
+  basic_resolver_iterator& operator=(const basic_resolver_iterator& other)
   {
-    basic_resolver_iterator iter;
-    if (begin != end)
-    {
-      iter.values_.reset(new values_type);
-      for (EndpointIterator ep_iter = begin; ep_iter != end; ++ep_iter)
-      {
-        iter.values_->push_back(
-            basic_resolver_entry<InternetProtocol>(
-              *ep_iter, host_name, service_name));
-      }
-    }
-    return iter;
+    values_ = other.values_;
+    index_ = other.index_;
+    return *this;
   }
 
-#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
-  /// Create an iterator from a Windows Runtime list of EndpointPair objects.
-  static basic_resolver_iterator create(
-      Windows::Foundation::Collections::IVectorView<
-        Windows::Networking::EndpointPair^>^ endpoints,
-      const boost::asio::detail::addrinfo_type& hints,
-      const std::string& host_name, const std::string& service_name)
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-assignment operator.
+  basic_resolver_iterator& operator=(basic_resolver_iterator&& other)
   {
-    basic_resolver_iterator iter;
-    if (endpoints->Size)
+    if (this != &other)
     {
-      iter.values_.reset(new values_type);
-      for (unsigned int i = 0; i < endpoints->Size; ++i)
-      {
-        auto pair = endpoints->GetAt(i);
-
-        if (hints.ai_family == BOOST_ASIO_OS_DEF(AF_INET)
-            && pair->RemoteHostName->Type
-              != Windows::Networking::HostNameType::Ipv4)
-          continue;
-
-        if (hints.ai_family == BOOST_ASIO_OS_DEF(AF_INET6)
-            && pair->RemoteHostName->Type
-              != Windows::Networking::HostNameType::Ipv6)
-          continue;
-
-        iter.values_->push_back(
-            basic_resolver_entry<InternetProtocol>(
-              typename InternetProtocol::endpoint(
-                ip::address::from_string(
-                  boost::asio::detail::winrt_utils::string(
-                    pair->RemoteHostName->CanonicalName)),
-                boost::asio::detail::winrt_utils::integer(
-                  pair->RemoteServiceName)),
-              host_name, service_name));
-      }
+      values_ = BOOST_ASIO_MOVE_CAST(values_ptr_type)(other.values_);
+      index_ = other.index_;
+      other.index_ = 0;
     }
-    return iter;
+
+    return *this;
   }
-#endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
   /// Dereference an iterator.
   const basic_resolver_entry<InternetProtocol>& operator*() const
@@ -223,7 +154,7 @@ class basic_resolver_iterator
     return !a.equal(b);
   }
 
-private:
+protected:
   void increment()
   {
     if (++index_ == values_->size())
@@ -249,7 +180,8 @@ class basic_resolver_iterator
   }
 
   typedef std::vector<basic_resolver_entry<InternetProtocol> > values_type;
-  boost::asio::detail::shared_ptr<values_type> values_;
+  typedef boost::asio::detail::shared_ptr<values_type> values_ptr_type;
+  values_ptr_type values_;
   std::size_t index_;
 };
 
diff --git a/include/boost/asio/ip/basic_resolver_results.hpp b/include/boost/asio/ip/basic_resolver_results.hpp
new file mode 100644
index 0000000000..bd3248a1a9
--- /dev/null
+++ b/include/boost/asio/ip/basic_resolver_results.hpp
@@ -0,0 +1,313 @@
+//
+// ip/basic_resolver_results.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_BASIC_RESOLVER_RESULTS_HPP
+#define BOOST_ASIO_IP_BASIC_RESOLVER_RESULTS_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <cstddef>
+#include <cstring>
+#include <boost/asio/detail/socket_ops.hpp>
+#include <boost/asio/detail/socket_types.hpp>
+#include <boost/asio/ip/basic_resolver_iterator.hpp>
+
+#if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+# include <boost/asio/detail/winrt_utils.hpp>
+#endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+/// A range of entries produced by a resolver.
+/**
+ * The boost::asio::ip::basic_resolver_results class template is used to define
+ * a range over the results returned by a resolver.
+ *
+ * The iterator's value_type, obtained when a results iterator is dereferenced,
+ * is: @code const basic_resolver_entry<InternetProtocol> @endcode
+ *
+ * @note For backward compatibility, basic_resolver_results is derived from
+ * basic_resolver_iterator. This derivation is deprecated.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+template <typename InternetProtocol>
+class basic_resolver_results
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  : public basic_resolver_iterator<InternetProtocol>
+#else // !defined(BOOST_ASIO_NO_DEPRECATED)
+  : private basic_resolver_iterator<InternetProtocol>
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+{
+public:
+  /// The protocol type associated with the results.
+  typedef InternetProtocol protocol_type;
+
+  /// The endpoint type associated with the results.
+  typedef typename protocol_type::endpoint endpoint_type;
+
+  /// The type of a value in the results range.
+  typedef basic_resolver_entry<endpoint_type> value_type;
+
+  /// The type of a const reference to a value in the range.
+  typedef const value_type& const_reference;
+
+  /// The type of a non-const reference to a value in the range.
+  typedef value_type& reference;
+
+  /// The type of an iterator into the range.
+  typedef basic_resolver_iterator<protocol_type> const_iterator;
+
+  /// The type of an iterator into the range.
+  typedef const_iterator iterator;
+
+  /// Type used to represent the distance between two iterators in the range.
+  typedef std::ptrdiff_t difference_type;
+
+  /// Type used to represent a count of the elements in the range.
+  typedef std::size_t size_type;
+
+  /// Default constructor creates an empty range.
+  basic_resolver_results()
+  {
+  }
+
+  /// Copy constructor.
+  basic_resolver_results(const basic_resolver_results& other)
+    : basic_resolver_iterator<InternetProtocol>(other)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move constructor.
+  basic_resolver_results(basic_resolver_results&& other)
+    : basic_resolver_iterator<InternetProtocol>(
+        BOOST_ASIO_MOVE_CAST(basic_resolver_results)(other))
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Assignment operator.
+  basic_resolver_results& operator=(const basic_resolver_results& other)
+  {
+    basic_resolver_iterator<InternetProtocol>::operator=(other);
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-assignment operator.
+  basic_resolver_results& operator=(basic_resolver_results&& other)
+  {
+    basic_resolver_iterator<InternetProtocol>::operator=(
+        BOOST_ASIO_MOVE_CAST(basic_resolver_results)(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+#if !defined(GENERATING_DOCUMENTATION)
+  // Create results from an addrinfo list returned by getaddrinfo.
+  static basic_resolver_results create(
+      boost::asio::detail::addrinfo_type* address_info,
+      const std::string& host_name, const std::string& service_name)
+  {
+    basic_resolver_results results;
+    if (!address_info)
+      return results;
+
+    std::string actual_host_name = host_name;
+    if (address_info->ai_canonname)
+      actual_host_name = address_info->ai_canonname;
+
+    results.values_.reset(new values_type);
+
+    while (address_info)
+    {
+      if (address_info->ai_family == BOOST_ASIO_OS_DEF(AF_INET)
+          || address_info->ai_family == BOOST_ASIO_OS_DEF(AF_INET6))
+      {
+        using namespace std; // For memcpy.
+        typename InternetProtocol::endpoint endpoint;
+        endpoint.resize(static_cast<std::size_t>(address_info->ai_addrlen));
+        memcpy(endpoint.data(), address_info->ai_addr,
+            address_info->ai_addrlen);
+        results.values_->push_back(
+            basic_resolver_entry<InternetProtocol>(endpoint,
+              actual_host_name, service_name));
+      }
+      address_info = address_info->ai_next;
+    }
+
+    return results;
+  }
+
+  // Create results from an endpoint, host name and service name.
+  static basic_resolver_results create(const endpoint_type& endpoint,
+      const std::string& host_name, const std::string& service_name)
+  {
+    basic_resolver_results results;
+    results.values_.reset(new values_type);
+    results.values_->push_back(
+        basic_resolver_entry<InternetProtocol>(
+          endpoint, host_name, service_name));
+    return results;
+  }
+
+  // Create results from a sequence of endpoints, host and service name.
+  template <typename EndpointIterator>
+  static basic_resolver_results create(
+      EndpointIterator begin, EndpointIterator end,
+      const std::string& host_name, const std::string& service_name)
+  {
+    basic_resolver_results results;
+    if (begin != end)
+    {
+      results.values_.reset(new values_type);
+      for (EndpointIterator ep_iter = begin; ep_iter != end; ++ep_iter)
+      {
+        results.values_->push_back(
+            basic_resolver_entry<InternetProtocol>(
+              *ep_iter, host_name, service_name));
+      }
+    }
+    return results;
+  }
+
+# if defined(BOOST_ASIO_WINDOWS_RUNTIME)
+  // Create results from a Windows Runtime list of EndpointPair objects.
+  static basic_resolver_results create(
+      Windows::Foundation::Collections::IVectorView<
+        Windows::Networking::EndpointPair^>^ endpoints,
+      const boost::asio::detail::addrinfo_type& hints,
+      const std::string& host_name, const std::string& service_name)
+  {
+    basic_resolver_results results;
+    if (endpoints->Size)
+    {
+      results.values_.reset(new values_type);
+      for (unsigned int i = 0; i < endpoints->Size; ++i)
+      {
+        auto pair = endpoints->GetAt(i);
+
+        if (hints.ai_family == BOOST_ASIO_OS_DEF(AF_INET)
+            && pair->RemoteHostName->Type
+              != Windows::Networking::HostNameType::Ipv4)
+          continue;
+
+        if (hints.ai_family == BOOST_ASIO_OS_DEF(AF_INET6)
+            && pair->RemoteHostName->Type
+              != Windows::Networking::HostNameType::Ipv6)
+          continue;
+
+        results.values_->push_back(
+            basic_resolver_entry<InternetProtocol>(
+              typename InternetProtocol::endpoint(
+                ip::make_address(
+                  boost::asio::detail::winrt_utils::string(
+                    pair->RemoteHostName->CanonicalName)),
+                boost::asio::detail::winrt_utils::integer(
+                  pair->RemoteServiceName)),
+              host_name, service_name));
+      }
+    }
+    return results;
+  }
+# endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+  /// Get the number of entries in the results range.
+  size_type size() const BOOST_ASIO_NOEXCEPT
+  {
+    return this->values_->size();
+  }
+
+  /// Get the maximum number of entries permitted in a results range.
+  size_type max_size() const BOOST_ASIO_NOEXCEPT
+  {
+    return this->values_->max_size();
+  }
+
+  /// Determine whether the results range is empty.
+  bool empty() const BOOST_ASIO_NOEXCEPT
+  {
+    return this->values_->empty();
+  }
+
+  /// Obtain a begin iterator for the results range.
+  const_iterator begin() const
+  {
+    basic_resolver_results tmp(*this);
+    tmp.index_ = 0;
+    return tmp;
+  }
+
+  /// Obtain an end iterator for the results range.
+  const_iterator end() const
+  {
+    return const_iterator();
+  }
+
+  /// Obtain a begin iterator for the results range.
+  const_iterator cbegin() const
+  {
+    return begin();
+  }
+
+  /// Obtain an end iterator for the results range.
+  const_iterator cend() const
+  {
+    return end();
+  }
+
+  /// Swap the results range with another.
+  void swap(basic_resolver_results& that) BOOST_ASIO_NOEXCEPT
+  {
+    if (this != &that)
+    {
+      this->values_.swap(that.values_);
+      std::size_t index = this->index_;
+      this->index_ = that.index_;
+      that.index_ = index;
+    }
+  }
+
+  /// Test two iterators for equality.
+  friend bool operator==(const basic_resolver_results& a,
+      const basic_resolver_results& b)
+  {
+    return a.equal(b);
+  }
+
+  /// Test two iterators for inequality.
+  friend bool operator!=(const basic_resolver_results& a,
+      const basic_resolver_results& b)
+  {
+    return !a.equal(b);
+  }
+
+private:
+  typedef std::vector<basic_resolver_entry<InternetProtocol> > values_type;
+};
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_BASIC_RESOLVER_RESULTS_HPP
diff --git a/include/boost/asio/ip/detail/endpoint.hpp b/include/boost/asio/ip/detail/endpoint.hpp
index 0a354e12a9..69a83a9e96 100644
--- a/include/boost/asio/ip/detail/endpoint.hpp
+++ b/include/boost/asio/ip/detail/endpoint.hpp
@@ -114,7 +114,7 @@ class endpoint
 
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
   // Convert to a string.
-  BOOST_ASIO_DECL std::string to_string(boost::system::error_code& ec) const;
+  BOOST_ASIO_DECL std::string to_string() const;
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
 
 private:
diff --git a/include/boost/asio/ip/detail/impl/endpoint.ipp b/include/boost/asio/ip/detail/impl/endpoint.ipp
index f1f9309af5..9908479327 100644
--- a/include/boost/asio/ip/detail/impl/endpoint.ipp
+++ b/include/boost/asio/ip/detail/impl/endpoint.ipp
@@ -81,8 +81,7 @@ endpoint::endpoint(const boost::asio::ip::address& addr,
       boost::asio::detail::socket_ops::host_to_network_short(port_num);
     data_.v4.sin_addr.s_addr =
       boost::asio::detail::socket_ops::host_to_network_long(
-          static_cast<boost::asio::detail::u_long_type>(
-            addr.to_v4().to_ulong()));
+        addr.to_v4().to_uint());
   }
   else
   {
@@ -178,18 +177,14 @@ bool operator<(const endpoint& e1, const endpoint& e2)
 }
 
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
-std::string endpoint::to_string(boost::system::error_code& ec) const
+std::string endpoint::to_string() const
 {
-  std::string a = address().to_string(ec);
-  if (ec)
-    return std::string();
-
   std::ostringstream tmp_os;
   tmp_os.imbue(std::locale::classic());
   if (is_v4())
-    tmp_os << a;
+    tmp_os << address();
   else
-    tmp_os << '[' << a << ']';
+    tmp_os << '[' << address() << ']';
   tmp_os << ':' << port();
 
   return tmp_os.str();
diff --git a/include/boost/asio/ip/detail/socket_option.hpp b/include/boost/asio/ip/detail/socket_option.hpp
index e8849fda92..e246ca0ef5 100644
--- a/include/boost/asio/ip/detail/socket_option.hpp
+++ b/include/boost/asio/ip/detail/socket_option.hpp
@@ -392,15 +392,15 @@ class multicast_request
   }
 
   // Construct with multicast address only.
-  explicit multicast_request(const boost::asio::ip::address& multicast_address)
+  explicit multicast_request(const address& multicast_address)
     : ipv4_value_(), // Zero-initialisation gives the "any" address.
       ipv6_value_() // Zero-initialisation gives the "any" address.
   {
     if (multicast_address.is_v6())
     {
       using namespace std; // For memcpy.
-      boost::asio::ip::address_v6 ipv6_address = multicast_address.to_v6();
-      boost::asio::ip::address_v6::bytes_type bytes = ipv6_address.to_bytes();
+      address_v6 ipv6_address = multicast_address.to_v6();
+      address_v6::bytes_type bytes = ipv6_address.to_bytes();
       memcpy(ipv6_value_.ipv6mr_multiaddr.s6_addr, bytes.data(), 16);
       ipv6_value_.ipv6mr_interface = ipv6_address.scope_id();
     }
@@ -408,37 +408,34 @@ class multicast_request
     {
       ipv4_value_.imr_multiaddr.s_addr =
         boost::asio::detail::socket_ops::host_to_network_long(
-            multicast_address.to_v4().to_ulong());
+            multicast_address.to_v4().to_uint());
       ipv4_value_.imr_interface.s_addr =
         boost::asio::detail::socket_ops::host_to_network_long(
-            boost::asio::ip::address_v4::any().to_ulong());
+            address_v4::any().to_uint());
     }
   }
 
   // Construct with multicast address and IPv4 address specifying an interface.
-  explicit multicast_request(
-      const boost::asio::ip::address_v4& multicast_address,
-      const boost::asio::ip::address_v4& network_interface
-        = boost::asio::ip::address_v4::any())
+  explicit multicast_request(const address_v4& multicast_address,
+      const address_v4& network_interface = address_v4::any())
     : ipv6_value_() // Zero-initialisation gives the "any" address.
   {
     ipv4_value_.imr_multiaddr.s_addr =
       boost::asio::detail::socket_ops::host_to_network_long(
-          multicast_address.to_ulong());
+          multicast_address.to_uint());
     ipv4_value_.imr_interface.s_addr =
       boost::asio::detail::socket_ops::host_to_network_long(
-          network_interface.to_ulong());
+          network_interface.to_uint());
   }
 
   // Construct with multicast address and IPv6 network interface index.
   explicit multicast_request(
-      const boost::asio::ip::address_v6& multicast_address,
+      const address_v6& multicast_address,
       unsigned long network_interface = 0)
     : ipv4_value_() // Zero-initialisation gives the "any" address.
   {
     using namespace std; // For memcpy.
-    boost::asio::ip::address_v6::bytes_type bytes =
-      multicast_address.to_bytes();
+    address_v6::bytes_type bytes = multicast_address.to_bytes();
     memcpy(ipv6_value_.ipv6mr_multiaddr.s6_addr, bytes.data(), 16);
     if (network_interface)
       ipv6_value_.ipv6mr_interface = network_interface;
@@ -497,16 +494,16 @@ class network_interface
   {
     ipv4_value_.s_addr =
       boost::asio::detail::socket_ops::host_to_network_long(
-          boost::asio::ip::address_v4::any().to_ulong());
+          address_v4::any().to_uint());
     ipv6_value_ = 0;
   }
 
   // Construct with IPv4 interface.
-  explicit network_interface(const boost::asio::ip::address_v4& ipv4_interface)
+  explicit network_interface(const address_v4& ipv4_interface)
   {
     ipv4_value_.s_addr =
       boost::asio::detail::socket_ops::host_to_network_long(
-          ipv4_interface.to_ulong());
+          ipv4_interface.to_uint());
     ipv6_value_ = 0;
   }
 
@@ -515,7 +512,7 @@ class network_interface
   {
     ipv4_value_.s_addr =
       boost::asio::detail::socket_ops::host_to_network_long(
-          boost::asio::ip::address_v4::any().to_ulong());
+          address_v4::any().to_uint());
     ipv6_value_ = ipv6_interface;
   }
 
diff --git a/include/boost/asio/ip/impl/address.hpp b/include/boost/asio/ip/impl/address.hpp
index e595d7063b..552cb5fd6d 100644
--- a/include/boost/asio/ip/impl/address.hpp
+++ b/include/boost/asio/ip/impl/address.hpp
@@ -25,23 +25,37 @@ namespace boost {
 namespace asio {
 namespace ip {
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+inline address address::from_string(const char* str)
+{
+  return boost::asio::ip::make_address(str);
+}
+
+inline address address::from_string(
+    const char* str, boost::system::error_code& ec)
+{
+  return boost::asio::ip::make_address(str, ec);
+}
+
+inline address address::from_string(const std::string& str)
+{
+  return boost::asio::ip::make_address(str);
+}
+
+inline address address::from_string(
+    const std::string& str, boost::system::error_code& ec)
+{
+  return boost::asio::ip::make_address(str, ec);
+}
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
 template <typename Elem, typename Traits>
 std::basic_ostream<Elem, Traits>& operator<<(
     std::basic_ostream<Elem, Traits>& os, const address& addr)
 {
-  boost::system::error_code ec;
-  std::string s = addr.to_string(ec);
-  if (ec)
-  {
-    if (os.exceptions() & std::basic_ostream<Elem, Traits>::failbit)
-      boost::asio::detail::throw_error(ec);
-    else
-      os.setstate(std::basic_ostream<Elem, Traits>::failbit);
-  }
-  else
-    for (std::string::iterator i = s.begin(); i != s.end(); ++i)
-      os << os.widen(*i);
-  return os;
+  return os << addr.to_string().c_str();
 }
 
 } // namespace ip
diff --git a/include/boost/asio/ip/impl/address.ipp b/include/boost/asio/ip/impl/address.ipp
index 5eda3e9ecf..6c615592e5 100644
--- a/include/boost/asio/ip/impl/address.ipp
+++ b/include/boost/asio/ip/impl/address.ipp
@@ -21,6 +21,7 @@
 #include <boost/asio/detail/throw_exception.hpp>
 #include <boost/asio/error.hpp>
 #include <boost/asio/ip/address.hpp>
+#include <boost/asio/ip/bad_address_cast.hpp>
 #include <boost/system/system_error.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -100,11 +101,60 @@ address& address::operator=(const boost::asio::ip::address_v6& ipv6_address)
   return *this;
 }
 
+address make_address(const char* str)
+{
+  boost::system::error_code ec;
+  address addr = make_address(str, ec);
+  boost::asio::detail::throw_error(ec);
+  return addr;
+}
+
+address make_address(const char* str, boost::system::error_code& ec)
+{
+  boost::asio::ip::address_v6 ipv6_address =
+    boost::asio::ip::make_address_v6(str, ec);
+  if (!ec)
+    return address(ipv6_address);
+
+  boost::asio::ip::address_v4 ipv4_address =
+    boost::asio::ip::make_address_v4(str, ec);
+  if (!ec)
+    return address(ipv4_address);
+
+  return address();
+}
+
+address make_address(const std::string& str)
+{
+  return make_address(str.c_str());
+}
+
+address make_address(const std::string& str,
+    boost::system::error_code& ec)
+{
+  return make_address(str.c_str(), ec);
+}
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+address make_address(string_view str)
+{
+  return make_address(static_cast<std::string>(str));
+}
+
+address make_address(string_view str,
+    boost::system::error_code& ec)
+{
+  return make_address(static_cast<std::string>(str), ec);
+}
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
 boost::asio::ip::address_v4 address::to_v4() const
 {
   if (type_ != ipv4)
   {
-    std::bad_cast ex;
+    bad_address_cast ex;
     boost::asio::detail::throw_exception(ex);
   }
   return ipv4_address_;
@@ -114,7 +164,7 @@ boost::asio::ip::address_v6 address::to_v6() const
 {
   if (type_ != ipv6)
   {
-    std::bad_cast ex;
+    bad_address_cast ex;
     boost::asio::detail::throw_exception(ex);
   }
   return ipv6_address_;
@@ -127,56 +177,14 @@ std::string address::to_string() const
   return ipv4_address_.to_string();
 }
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 std::string address::to_string(boost::system::error_code& ec) const
 {
   if (type_ == ipv6)
     return ipv6_address_.to_string(ec);
   return ipv4_address_.to_string(ec);
 }
-
-address address::from_string(const char* str)
-{
-  boost::system::error_code ec;
-  address addr = from_string(str, ec);
-  boost::asio::detail::throw_error(ec);
-  return addr;
-}
-
-address address::from_string(const char* str, boost::system::error_code& ec)
-{
-  boost::asio::ip::address_v6 ipv6_address =
-    boost::asio::ip::address_v6::from_string(str, ec);
-  if (!ec)
-  {
-    address tmp;
-    tmp.type_ = ipv6;
-    tmp.ipv6_address_ = ipv6_address;
-    return tmp;
-  }
-
-  boost::asio::ip::address_v4 ipv4_address =
-    boost::asio::ip::address_v4::from_string(str, ec);
-  if (!ec)
-  {
-    address tmp;
-    tmp.type_ = ipv4;
-    tmp.ipv4_address_ = ipv4_address;
-    return tmp;
-  }
-
-  return address();
-}
-
-address address::from_string(const std::string& str)
-{
-  return from_string(str.c_str());
-}
-
-address address::from_string(const std::string& str,
-    boost::system::error_code& ec)
-{
-  return from_string(str.c_str(), ec);
-}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 bool address::is_loopback() const
 {
diff --git a/include/boost/asio/ip/impl/address_v4.hpp b/include/boost/asio/ip/impl/address_v4.hpp
index 028b69b676..a273f5e73e 100644
--- a/include/boost/asio/ip/impl/address_v4.hpp
+++ b/include/boost/asio/ip/impl/address_v4.hpp
@@ -25,23 +25,37 @@ namespace boost {
 namespace asio {
 namespace ip {
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+inline address_v4 address_v4::from_string(const char* str)
+{
+  return boost::asio::ip::make_address_v4(str);
+}
+
+inline address_v4 address_v4::from_string(
+    const char* str, boost::system::error_code& ec)
+{
+  return boost::asio::ip::make_address_v4(str, ec);
+}
+
+inline address_v4 address_v4::from_string(const std::string& str)
+{
+  return boost::asio::ip::make_address_v4(str);
+}
+
+inline address_v4 address_v4::from_string(
+    const std::string& str, boost::system::error_code& ec)
+{
+  return boost::asio::ip::make_address_v4(str, ec);
+}
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
 template <typename Elem, typename Traits>
 std::basic_ostream<Elem, Traits>& operator<<(
     std::basic_ostream<Elem, Traits>& os, const address_v4& addr)
 {
-  boost::system::error_code ec;
-  std::string s = addr.to_string(ec);
-  if (ec)
-  {
-    if (os.exceptions() & std::basic_ostream<Elem, Traits>::failbit)
-      boost::asio::detail::throw_error(ec);
-    else
-      os.setstate(std::basic_ostream<Elem, Traits>::failbit);
-  }
-  else
-    for (std::string::iterator i = s.begin(); i != s.end(); ++i)
-      os << os.widen(*i);
-  return os;
+  return os << addr.to_string().c_str();
 }
 
 } // namespace ip
diff --git a/include/boost/asio/ip/impl/address_v4.ipp b/include/boost/asio/ip/impl/address_v4.ipp
index 440217bcb2..d6db61f80d 100644
--- a/include/boost/asio/ip/impl/address_v4.ipp
+++ b/include/boost/asio/ip/impl/address_v4.ipp
@@ -17,6 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <climits>
+#include <limits>
 #include <stdexcept>
 #include <boost/asio/error.hpp>
 #include <boost/asio/detail/socket_ops.hpp>
@@ -45,15 +46,13 @@ address_v4::address_v4(const address_v4::bytes_type& bytes)
   memcpy(&addr_.s_addr, bytes.data(), 4);
 }
 
-address_v4::address_v4(unsigned long addr)
+address_v4::address_v4(address_v4::uint_type addr)
 {
-#if ULONG_MAX > 0xFFFFFFFF
-  if (addr > 0xFFFFFFFF)
+  if ((std::numeric_limits<uint_type>::max)() > 0xFFFFFFFF)
   {
-    std::out_of_range ex("address_v4 from unsigned long");
+    std::out_of_range ex("address_v4 from unsigned integer");
     boost::asio::detail::throw_exception(ex);
   }
-#endif // ULONG_MAX > 0xFFFFFFFF
 
   addr_.s_addr = boost::asio::detail::socket_ops::host_to_network_long(
       static_cast<boost::asio::detail::u_long_type>(addr));
@@ -71,19 +70,32 @@ address_v4::bytes_type address_v4::to_bytes() const
   return bytes;
 }
 
+address_v4::uint_type address_v4::to_uint() const
+{
+  return boost::asio::detail::socket_ops::network_to_host_long(addr_.s_addr);
+}
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 unsigned long address_v4::to_ulong() const
 {
   return boost::asio::detail::socket_ops::network_to_host_long(addr_.s_addr);
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 std::string address_v4::to_string() const
 {
   boost::system::error_code ec;
-  std::string addr = to_string(ec);
-  boost::asio::detail::throw_error(ec);
+  char addr_str[boost::asio::detail::max_addr_v4_str_len];
+  const char* addr =
+    boost::asio::detail::socket_ops::inet_ntop(
+        BOOST_ASIO_OS_DEF(AF_INET), &addr_, addr_str,
+        boost::asio::detail::max_addr_v4_str_len, 0, ec);
+  if (addr == 0)
+    boost::asio::detail::throw_error(ec);
   return addr;
 }
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 std::string address_v4::to_string(boost::system::error_code& ec) const
 {
   char addr_str[boost::asio::detail::max_addr_v4_str_len];
@@ -95,69 +107,44 @@ std::string address_v4::to_string(boost::system::error_code& ec) const
     return std::string();
   return addr;
 }
-
-address_v4 address_v4::from_string(const char* str)
-{
-  boost::system::error_code ec;
-  address_v4 addr = from_string(str, ec);
-  boost::asio::detail::throw_error(ec);
-  return addr;
-}
-
-address_v4 address_v4::from_string(
-    const char* str, boost::system::error_code& ec)
-{
-  address_v4 tmp;
-  if (boost::asio::detail::socket_ops::inet_pton(
-        BOOST_ASIO_OS_DEF(AF_INET), str, &tmp.addr_, 0, ec) <= 0)
-    return address_v4();
-  return tmp;
-}
-
-address_v4 address_v4::from_string(const std::string& str)
-{
-  return from_string(str.c_str());
-}
-
-address_v4 address_v4::from_string(
-    const std::string& str, boost::system::error_code& ec)
-{
-  return from_string(str.c_str(), ec);
-}
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 bool address_v4::is_loopback() const
 {
-  return (to_ulong() & 0xFF000000) == 0x7F000000;
+  return (to_uint() & 0xFF000000) == 0x7F000000;
 }
 
 bool address_v4::is_unspecified() const
 {
-  return to_ulong() == 0;
+  return to_uint() == 0;
 }
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 bool address_v4::is_class_a() const
 {
-  return (to_ulong() & 0x80000000) == 0;
+  return (to_uint() & 0x80000000) == 0;
 }
 
 bool address_v4::is_class_b() const
 {
-  return (to_ulong() & 0xC0000000) == 0x80000000;
+  return (to_uint() & 0xC0000000) == 0x80000000;
 }
 
 bool address_v4::is_class_c() const
 {
-  return (to_ulong() & 0xE0000000) == 0xC0000000;
+  return (to_uint() & 0xE0000000) == 0xC0000000;
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 bool address_v4::is_multicast() const
 {
-  return (to_ulong() & 0xF0000000) == 0xE0000000;
+  return (to_uint() & 0xF0000000) == 0xE0000000;
 }
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 address_v4 address_v4::broadcast(const address_v4& addr, const address_v4& mask)
 {
-  return address_v4(addr.to_ulong() | (mask.to_ulong() ^ 0xFFFFFFFF));
+  return address_v4(addr.to_uint() | (mask.to_uint() ^ 0xFFFFFFFF));
 }
 
 address_v4 address_v4::netmask(const address_v4& addr)
@@ -170,6 +157,51 @@ address_v4 address_v4::netmask(const address_v4& addr)
     return address_v4(0xFFFFFF00);
   return address_v4(0xFFFFFFFF);
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+address_v4 make_address_v4(const char* str)
+{
+  boost::system::error_code ec;
+  address_v4 addr = make_address_v4(str, ec);
+  boost::asio::detail::throw_error(ec);
+  return addr;
+}
+
+address_v4 make_address_v4(
+    const char* str, boost::system::error_code& ec)
+{
+  address_v4::bytes_type bytes;
+  if (boost::asio::detail::socket_ops::inet_pton(
+        BOOST_ASIO_OS_DEF(AF_INET), str, &bytes, 0, ec) <= 0)
+    return address_v4();
+  return address_v4(bytes);
+}
+
+address_v4 make_address_v4(const std::string& str)
+{
+  return make_address_v4(str.c_str());
+}
+
+address_v4 make_address_v4(
+    const std::string& str, boost::system::error_code& ec)
+{
+  return make_address_v4(str.c_str(), ec);
+}
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+address_v4 make_address_v4(string_view str)
+{
+  return make_address_v4(static_cast<std::string>(str));
+}
+
+address_v4 make_address_v4(string_view str,
+    boost::system::error_code& ec)
+{
+  return make_address_v4(static_cast<std::string>(str), ec);
+}
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
 
 } // namespace ip
 } // namespace asio
diff --git a/include/boost/asio/ip/impl/address_v6.hpp b/include/boost/asio/ip/impl/address_v6.hpp
index 4b88129c50..e1d9932d30 100644
--- a/include/boost/asio/ip/impl/address_v6.hpp
+++ b/include/boost/asio/ip/impl/address_v6.hpp
@@ -25,23 +25,37 @@ namespace boost {
 namespace asio {
 namespace ip {
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+inline address_v6 address_v6::from_string(const char* str)
+{
+  return boost::asio::ip::make_address_v6(str);
+}
+
+inline address_v6 address_v6::from_string(
+    const char* str, boost::system::error_code& ec)
+{
+  return boost::asio::ip::make_address_v6(str, ec);
+}
+
+inline address_v6 address_v6::from_string(const std::string& str)
+{
+  return boost::asio::ip::make_address_v6(str);
+}
+
+inline address_v6 address_v6::from_string(
+    const std::string& str, boost::system::error_code& ec)
+{
+  return boost::asio::ip::make_address_v6(str, ec);
+}
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
 template <typename Elem, typename Traits>
 std::basic_ostream<Elem, Traits>& operator<<(
     std::basic_ostream<Elem, Traits>& os, const address_v6& addr)
 {
-  boost::system::error_code ec;
-  std::string s = addr.to_string(ec);
-  if (ec)
-  {
-    if (os.exceptions() & std::basic_ostream<Elem, Traits>::failbit)
-      boost::asio::detail::throw_error(ec);
-    else
-      os.setstate(std::basic_ostream<Elem, Traits>::failbit);
-  }
-  else
-    for (std::string::iterator i = s.begin(); i != s.end(); ++i)
-      os << os.widen(*i);
-  return os;
+  return os << addr.to_string().c_str();
 }
 
 } // namespace ip
diff --git a/include/boost/asio/ip/impl/address_v6.ipp b/include/boost/asio/ip/impl/address_v6.ipp
index 2d1a1974bf..1741bbcf79 100644
--- a/include/boost/asio/ip/impl/address_v6.ipp
+++ b/include/boost/asio/ip/impl/address_v6.ipp
@@ -24,6 +24,7 @@
 #include <boost/asio/detail/throw_exception.hpp>
 #include <boost/asio/error.hpp>
 #include <boost/asio/ip/address_v6.hpp>
+#include <boost/asio/ip/bad_address_cast.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -101,11 +102,17 @@ address_v6::bytes_type address_v6::to_bytes() const
 std::string address_v6::to_string() const
 {
   boost::system::error_code ec;
-  std::string addr = to_string(ec);
-  boost::asio::detail::throw_error(ec);
+  char addr_str[boost::asio::detail::max_addr_v6_str_len];
+  const char* addr =
+    boost::asio::detail::socket_ops::inet_ntop(
+        BOOST_ASIO_OS_DEF(AF_INET6), &addr_, addr_str,
+        boost::asio::detail::max_addr_v6_str_len, scope_id_, ec);
+  if (addr == 0)
+    boost::asio::detail::throw_error(ec);
   return addr;
 }
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 std::string address_v6::to_string(boost::system::error_code& ec) const
 {
   char addr_str[boost::asio::detail::max_addr_v6_str_len];
@@ -118,40 +125,11 @@ std::string address_v6::to_string(boost::system::error_code& ec) const
   return addr;
 }
 
-address_v6 address_v6::from_string(const char* str)
-{
-  boost::system::error_code ec;
-  address_v6 addr = from_string(str, ec);
-  boost::asio::detail::throw_error(ec);
-  return addr;
-}
-
-address_v6 address_v6::from_string(
-    const char* str, boost::system::error_code& ec)
-{
-  address_v6 tmp;
-  if (boost::asio::detail::socket_ops::inet_pton(
-        BOOST_ASIO_OS_DEF(AF_INET6), str, &tmp.addr_, &tmp.scope_id_, ec) <= 0)
-    return address_v6();
-  return tmp;
-}
-
-address_v6 address_v6::from_string(const std::string& str)
-{
-  return from_string(str.c_str());
-}
-
-address_v6 address_v6::from_string(
-    const std::string& str, boost::system::error_code& ec)
-{
-  return from_string(str.c_str(), ec);
-}
-
 address_v4 address_v6::to_v4() const
 {
   if (!is_v4_mapped() && !is_v4_compatible())
   {
-    std::bad_cast ex;
+    bad_address_cast ex;
     boost::asio::detail::throw_exception(ex);
   }
 
@@ -159,6 +137,7 @@ address_v4 address_v6::to_v4() const
     addr_.s6_addr[13], addr_.s6_addr[14], addr_.s6_addr[15] } };
   return address_v4(v4_bytes);
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 bool address_v6::is_loopback() const
 {
@@ -204,6 +183,7 @@ bool address_v6::is_v4_mapped() const
       && (addr_.s6_addr[10] == 0xff) && (addr_.s6_addr[11] == 0xff));
 }
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 bool address_v6::is_v4_compatible() const
 {
   return ((addr_.s6_addr[0] == 0) && (addr_.s6_addr[1] == 0)
@@ -217,6 +197,7 @@ bool address_v6::is_v4_compatible() const
         && (addr_.s6_addr[14] == 0)
         && ((addr_.s6_addr[15] == 0) || (addr_.s6_addr[15] == 1))));
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 bool address_v6::is_multicast() const
 {
@@ -275,6 +256,7 @@ address_v6 address_v6::loopback()
   return tmp;
 }
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
 address_v6 address_v6::v4_mapped(const address_v4& addr)
 {
   address_v4::bytes_type v4_bytes = addr.to_bytes();
@@ -290,6 +272,76 @@ address_v6 address_v6::v4_compatible(const address_v4& addr)
     v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] } };
   return address_v6(v6_bytes);
 }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+address_v6 make_address_v6(const char* str)
+{
+  boost::system::error_code ec;
+  address_v6 addr = make_address_v6(str, ec);
+  boost::asio::detail::throw_error(ec);
+  return addr;
+}
+
+address_v6 make_address_v6(
+    const char* str, boost::system::error_code& ec)
+{
+  address_v6::bytes_type bytes;
+  unsigned long scope_id = 0;
+  if (boost::asio::detail::socket_ops::inet_pton(
+        BOOST_ASIO_OS_DEF(AF_INET6), str, &bytes[0], &scope_id, ec) <= 0)
+    return address_v6();
+  return address_v6(bytes, scope_id);
+}
+
+address_v6 make_address_v6(const std::string& str)
+{
+  return make_address_v6(str.c_str());
+}
+
+address_v6 make_address_v6(
+    const std::string& str, boost::system::error_code& ec)
+{
+  return make_address_v6(str.c_str(), ec);
+}
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+address_v6 make_address_v6(string_view str)
+{
+  return make_address_v6(static_cast<std::string>(str));
+}
+
+address_v6 make_address_v6(string_view str,
+    boost::system::error_code& ec)
+{
+  return make_address_v6(static_cast<std::string>(str), ec);
+}
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+address_v4 make_address_v4(
+    v4_mapped_t, const address_v6& v6_addr)
+{
+  if (!v6_addr.is_v4_mapped())
+  {
+    bad_address_cast ex;
+    boost::asio::detail::throw_exception(ex);
+  }
+
+  address_v6::bytes_type v6_bytes = v6_addr.to_bytes();
+  address_v4::bytes_type v4_bytes = { { v6_bytes[12],
+    v6_bytes[13], v6_bytes[14], v6_bytes[15] } };
+  return address_v4(v4_bytes);
+}
+
+address_v6 make_address_v6(
+    v4_mapped_t, const address_v4& v4_addr)
+{
+  address_v4::bytes_type v4_bytes = v4_addr.to_bytes();
+  address_v6::bytes_type v6_bytes = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0xFF, 0xFF, v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] } };
+  return address_v6(v6_bytes);
+}
 
 } // namespace ip
 } // namespace asio
diff --git a/include/boost/asio/ip/impl/basic_endpoint.hpp b/include/boost/asio/ip/impl/basic_endpoint.hpp
index 4d9c4505c3..590e9748f3 100644
--- a/include/boost/asio/ip/impl/basic_endpoint.hpp
+++ b/include/boost/asio/ip/impl/basic_endpoint.hpp
@@ -31,19 +31,7 @@ std::basic_ostream<Elem, Traits>& operator<<(
     const basic_endpoint<InternetProtocol>& endpoint)
 {
   boost::asio::ip::detail::endpoint tmp_ep(endpoint.address(), endpoint.port());
-  boost::system::error_code ec;
-  std::string s = tmp_ep.to_string(ec);
-  if (ec)
-  {
-    if (os.exceptions() & std::basic_ostream<Elem, Traits>::failbit)
-      boost::asio::detail::throw_error(ec);
-    else
-      os.setstate(std::basic_ostream<Elem, Traits>::failbit);
-  }
-  else
-    for (std::string::iterator i = s.begin(); i != s.end(); ++i)
-      os << os.widen(*i);
-  return os;
+  return os << tmp_ep.to_string().c_str();
 }
 
 } // namespace ip
diff --git a/include/boost/asio/ip/impl/network_v4.hpp b/include/boost/asio/ip/impl/network_v4.hpp
new file mode 100644
index 0000000000..6d9ebaa184
--- /dev/null
+++ b/include/boost/asio/ip/impl/network_v4.hpp
@@ -0,0 +1,56 @@
+//
+// ip/impl/network_v4.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_IMPL_NETWORK_V4_HPP
+#define BOOST_ASIO_IP_IMPL_NETWORK_V4_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+#include <boost/asio/detail/throw_error.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+template <typename Elem, typename Traits>
+std::basic_ostream<Elem, Traits>& operator<<(
+    std::basic_ostream<Elem, Traits>& os, const network_v4& addr)
+{
+  boost::system::error_code ec;
+  std::string s = addr.to_string(ec);
+  if (ec)
+  {
+    if (os.exceptions() & std::basic_ostream<Elem, Traits>::failbit)
+      boost::asio::detail::throw_error(ec);
+    else
+      os.setstate(std::basic_ostream<Elem, Traits>::failbit);
+  }
+  else
+    for (std::string::iterator i = s.begin(); i != s.end(); ++i)
+      os << os.widen(*i);
+  return os;
+}
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+
+#endif // BOOST_ASIO_IP_IMPL_NETWORK_V4_HPP
diff --git a/include/boost/asio/ip/impl/network_v4.ipp b/include/boost/asio/ip/impl/network_v4.ipp
new file mode 100644
index 0000000000..c54a8b0e8b
--- /dev/null
+++ b/include/boost/asio/ip/impl/network_v4.ipp
@@ -0,0 +1,210 @@
+//
+// ip/impl/network_v4.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_IMPL_NETWORK_V4_IPP
+#define BOOST_ASIO_IP_IMPL_NETWORK_V4_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <climits>
+#include <cstdio>
+#include <cstdlib>
+#include <stdexcept>
+#include <boost/asio/error.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/detail/throw_exception.hpp>
+#include <boost/asio/ip/network_v4.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+network_v4::network_v4(const address_v4& addr, unsigned short prefix_len)
+  : address_(addr),
+    prefix_length_(prefix_len)
+{
+  if (prefix_len > 32)
+  {
+    std::out_of_range ex("prefix length too large");
+    boost::asio::detail::throw_exception(ex);
+  }
+}
+
+network_v4::network_v4(const address_v4& addr, const address_v4& mask)
+  : address_(addr),
+    prefix_length_(0)
+{
+  address_v4::bytes_type mask_bytes = mask.to_bytes();
+  bool finished = false;
+  for (std::size_t i = 0; i < mask_bytes.size(); ++i)
+  {
+    if (finished)
+    {
+      if (mask_bytes[i])
+      {
+        std::invalid_argument ex("non-contiguous netmask");
+        boost::asio::detail::throw_exception(ex);
+      }
+      continue;
+    }
+    else
+    {
+      switch (mask_bytes[i])
+      {
+      case 255:
+        prefix_length_ += 8;
+        break;
+      case 254: // prefix_length_ += 7
+        prefix_length_ += 1;
+      case 252: // prefix_length_ += 6
+        prefix_length_ += 1;
+      case 248: // prefix_length_ += 5
+        prefix_length_ += 1;
+      case 240: // prefix_length_ += 4
+        prefix_length_ += 1;
+      case 224: // prefix_length_ += 3
+        prefix_length_ += 1;
+      case 192: // prefix_length_ += 2
+        prefix_length_ += 1;
+      case 128: // prefix_length_ += 1
+        prefix_length_ += 1;
+      case 0:   // nbits += 0
+        finished = true;
+        break;
+      default:
+        std::out_of_range ex("non-contiguous netmask");
+        boost::asio::detail::throw_exception(ex);
+      }
+    }
+  }
+}
+
+address_v4 network_v4::netmask() const BOOST_ASIO_NOEXCEPT
+{
+  uint32_t nmbits = 0xffffffff;
+  if (prefix_length_ == 0)
+    nmbits = 0;
+  else
+    nmbits = nmbits << (32 - prefix_length_);
+  return address_v4(nmbits);
+}
+
+address_v4_range network_v4::hosts() const BOOST_ASIO_NOEXCEPT
+{
+  return is_host()
+    ? address_v4_range(address_, address_v4(address_.to_uint() + 1))
+    : address_v4_range(address_v4(network().to_uint() + 1), broadcast());
+}
+
+bool network_v4::is_subnet_of(const network_v4& other) const
+{
+  if (other.prefix_length_ >= prefix_length_)
+    return false; // Only real subsets are allowed.
+  const network_v4 me(address_, other.prefix_length_);
+  return other.canonical() == me.canonical();
+}
+
+std::string network_v4::to_string() const
+{
+  boost::system::error_code ec;
+  std::string addr = to_string(ec);
+  boost::asio::detail::throw_error(ec);
+  return addr;
+}
+
+std::string network_v4::to_string(boost::system::error_code& ec) const
+{
+  ec = boost::system::error_code();
+  char prefix_len[16];
+#if defined(BOOST_ASIO_HAS_SECURE_RTL)
+  sprintf_s(prefix_len, sizeof(prefix_len), "/%u", prefix_length_);
+#else // defined(BOOST_ASIO_HAS_SECURE_RTL)
+  sprintf(prefix_len, "/%u", prefix_length_);
+#endif // defined(BOOST_ASIO_HAS_SECURE_RTL)
+  return address_.to_string() + prefix_len;
+}
+
+network_v4 make_network_v4(const char* str)
+{
+  return make_network_v4(std::string(str));
+}
+
+network_v4 make_network_v4(const char* str, boost::system::error_code& ec)
+{
+  return make_network_v4(std::string(str), ec);
+}
+
+network_v4 make_network_v4(const std::string& str)
+{
+  boost::system::error_code ec;
+  network_v4 net = make_network_v4(str, ec);
+  boost::asio::detail::throw_error(ec);
+  return net;
+}
+
+network_v4 make_network_v4(const std::string& str,
+    boost::system::error_code& ec)
+{
+  std::string::size_type pos = str.find_first_of("/");
+
+  if (pos == std::string::npos)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return network_v4();
+  }
+
+  if (pos == str.size() - 1)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return network_v4();
+  }
+
+  std::string::size_type end = str.find_first_not_of("0123456789", pos + 1);
+  if (end != std::string::npos)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return network_v4();
+  }
+
+  const address_v4 addr = make_address_v4(str.substr(0, pos), ec);
+  if (ec)
+    return network_v4();
+
+  return network_v4(addr, std::atoi(str.substr(pos + 1).c_str()));
+}
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+network_v4 make_network_v4(string_view str)
+{
+  return make_network_v4(static_cast<std::string>(str));
+}
+
+network_v4 make_network_v4(string_view str,
+    boost::system::error_code& ec)
+{
+  return make_network_v4(static_cast<std::string>(str), ec);
+}
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_IMPL_NETWORK_V4_IPP
diff --git a/include/boost/asio/ip/impl/network_v6.hpp b/include/boost/asio/ip/impl/network_v6.hpp
new file mode 100644
index 0000000000..c6bac2d2db
--- /dev/null
+++ b/include/boost/asio/ip/impl/network_v6.hpp
@@ -0,0 +1,55 @@
+//
+// ip/impl/network_v6.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_IMPL_NETWORK_V6_HPP
+#define BOOST_ASIO_IP_IMPL_NETWORK_V6_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+#include <boost/asio/detail/throw_error.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+template <typename Elem, typename Traits>
+std::basic_ostream<Elem, Traits>& operator<<(
+    std::basic_ostream<Elem, Traits>& os, const network_v6& addr)
+{
+  boost::system::error_code ec;
+  std::string s = addr.to_string(ec);
+  if (ec)
+  {
+    if (os.exceptions() & std::basic_ostream<Elem, Traits>::failbit)
+      boost::asio::detail::throw_error(ec);
+    else
+      os.setstate(std::basic_ostream<Elem, Traits>::failbit);
+  }
+  else
+    for (std::string::iterator i = s.begin(); i != s.end(); ++i)
+      os << os.widen(*i);
+  return os;
+}
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+
+#endif // BOOST_ASIO_IP_IMPL_NETWORK_V6_HPP
diff --git a/include/boost/asio/ip/impl/network_v6.ipp b/include/boost/asio/ip/impl/network_v6.ipp
new file mode 100644
index 0000000000..cafd898c00
--- /dev/null
+++ b/include/boost/asio/ip/impl/network_v6.ipp
@@ -0,0 +1,179 @@
+//
+// ip/impl/network_v6.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_IMPL_NETWORK_V6_IPP
+#define BOOST_ASIO_IP_IMPL_NETWORK_V6_IPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <climits>
+#include <cstdio>
+#include <cstdlib>
+#include <stdexcept>
+#include <boost/asio/error.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/detail/throw_exception.hpp>
+#include <boost/asio/ip/network_v6.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+network_v6::network_v6(const address_v6& addr, unsigned short prefix_len)
+  : address_(addr),
+    prefix_length_(prefix_len)
+{
+  if (prefix_len > 128)
+  {
+    std::out_of_range ex("prefix length too large");
+    boost::asio::detail::throw_exception(ex);
+  }
+}
+
+BOOST_ASIO_DECL address_v6 network_v6::network() const BOOST_ASIO_NOEXCEPT
+{
+  address_v6::bytes_type bytes(address_.to_bytes());
+  for (std::size_t i = 0; i < 16; ++i)
+  {
+    if (prefix_length_ <= i * 8)
+      bytes[i] = 0;
+    else if (prefix_length_ < (i + 1) * 8)
+      bytes[i] &= 0xFF00 >> (prefix_length_ % 8);
+  }
+  return address_v6(bytes, address_.scope_id());
+}
+
+address_v6_range network_v6::hosts() const BOOST_ASIO_NOEXCEPT
+{
+  address_v6::bytes_type begin_bytes(address_.to_bytes());
+  address_v6::bytes_type end_bytes(address_.to_bytes());
+  for (std::size_t i = 0; i < 16; ++i)
+  {
+    if (prefix_length_ <= i * 8)
+    {
+      begin_bytes[i] = 0;
+      end_bytes[i] = 0xFF;
+    }
+    else if (prefix_length_ < (i + 1) * 8)
+    {
+      begin_bytes[i] &= 0xFF00 >> (prefix_length_ % 8);
+      end_bytes[i] |= 0xFF >> (prefix_length_ % 8);
+    }
+  }
+  return address_v6_range(
+      address_v6_iterator(address_v6(begin_bytes, address_.scope_id())),
+      ++address_v6_iterator(address_v6(end_bytes, address_.scope_id())));
+}
+
+bool network_v6::is_subnet_of(const network_v6& other) const
+{
+  if (other.prefix_length_ >= prefix_length_)
+    return false; // Only real subsets are allowed.
+  const network_v6 me(address_, other.prefix_length_);
+  return other.canonical() == me.canonical();
+}
+
+std::string network_v6::to_string() const
+{
+  boost::system::error_code ec;
+  std::string addr = to_string(ec);
+  boost::asio::detail::throw_error(ec);
+  return addr;
+}
+
+std::string network_v6::to_string(boost::system::error_code& ec) const
+{
+  ec = boost::system::error_code();
+  char prefix_len[16];
+#if defined(BOOST_ASIO_HAS_SECURE_RTL)
+  sprintf_s(prefix_len, sizeof(prefix_len), "/%u", prefix_length_);
+#else // defined(BOOST_ASIO_HAS_SECURE_RTL)
+  sprintf(prefix_len, "/%u", prefix_length_);
+#endif // defined(BOOST_ASIO_HAS_SECURE_RTL)
+  return address_.to_string() + prefix_len;
+}
+
+network_v6 make_network_v6(const char* str)
+{
+  return make_network_v6(std::string(str));
+}
+
+network_v6 make_network_v6(const char* str, boost::system::error_code& ec)
+{
+  return make_network_v6(std::string(str), ec);
+}
+
+network_v6 make_network_v6(const std::string& str)
+{
+  boost::system::error_code ec;
+  network_v6 net = make_network_v6(str, ec);
+  boost::asio::detail::throw_error(ec);
+  return net;
+}
+
+network_v6 make_network_v6(const std::string& str,
+    boost::system::error_code& ec)
+{
+  std::string::size_type pos = str.find_first_of("/");
+
+  if (pos == std::string::npos)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return network_v6();
+  }
+
+  if (pos == str.size() - 1)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return network_v6();
+  }
+
+  std::string::size_type end = str.find_first_not_of("0123456789", pos + 1);
+  if (end != std::string::npos)
+  {
+    ec = boost::asio::error::invalid_argument;
+    return network_v6();
+  }
+
+  const address_v6 addr = make_address_v6(str.substr(0, pos), ec);
+  if (ec)
+    return network_v6();
+
+  return network_v6(addr, std::atoi(str.substr(pos + 1).c_str()));
+}
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+network_v6 make_network_v6(string_view str)
+{
+  return make_network_v6(static_cast<std::string>(str));
+}
+
+network_v6 make_network_v6(string_view str,
+    boost::system::error_code& ec)
+{
+  return make_network_v6(static_cast<std::string>(str), ec);
+}
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_IMPL_NETWORK_V6_IPP
diff --git a/include/boost/asio/ip/multicast.hpp b/include/boost/asio/ip/multicast.hpp
index d82e442116..86c6389096 100644
--- a/include/boost/asio/ip/multicast.hpp
+++ b/include/boost/asio/ip/multicast.hpp
@@ -33,7 +33,7 @@ namespace multicast {
  * @par Examples
  * Setting the option to join a multicast group:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::address multicast_address =
  *   boost::asio::ip::address::from_string("225.0.0.1");
@@ -61,7 +61,7 @@ typedef boost::asio::ip::detail::socket_option::multicast_request<
  * @par Examples
  * Setting the option to leave a multicast group:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::address multicast_address =
  *   boost::asio::ip::address::from_string("225.0.0.1");
@@ -89,7 +89,7 @@ typedef boost::asio::ip::detail::socket_option::multicast_request<
  * @par Examples
  * Setting the option:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::address_v4 local_interface =
  *   boost::asio::ip::address_v4::from_string("1.2.3.4");
@@ -117,7 +117,7 @@ typedef boost::asio::ip::detail::socket_option::network_interface<
  * @par Examples
  * Setting the option:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::multicast::hops option(4);
  * socket.set_option(option);
@@ -126,7 +126,7 @@ typedef boost::asio::ip::detail::socket_option::network_interface<
  * @par
  * Getting the current option value:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::multicast::hops option;
  * socket.get_option(option);
@@ -154,7 +154,7 @@ typedef boost::asio::ip::detail::socket_option::multicast_hops<
  * @par Examples
  * Setting the option:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::multicast::enable_loopback option(true);
  * socket.set_option(option);
@@ -163,7 +163,7 @@ typedef boost::asio::ip::detail::socket_option::multicast_hops<
  * @par
  * Getting the current option value:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::multicast::enable_loopback option;
  * socket.get_option(option);
diff --git a/include/boost/asio/ip/network_v4.hpp b/include/boost/asio/ip/network_v4.hpp
new file mode 100644
index 0000000000..f0b8ecb164
--- /dev/null
+++ b/include/boost/asio/ip/network_v4.hpp
@@ -0,0 +1,263 @@
+//
+// ip/network_v4.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_NETWORK_V4_HPP
+#define BOOST_ASIO_IP_NETWORK_V4_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <string>
+#include <boost/asio/detail/string_view.hpp>
+#include <boost/system/error_code.hpp>
+#include <boost/asio/ip/address_v4_range.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+/// Represents an IPv4 network.
+/**
+ * The boost::asio::ip::network_v4 class provides the ability to use and
+ * manipulate IP version 4 networks.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+class network_v4
+{
+public:
+  /// Default constructor.
+  network_v4() BOOST_ASIO_NOEXCEPT
+    : address_(),
+      prefix_length_(0)
+  {
+  }
+
+  /// Construct a network based on the specified address and prefix length.
+  BOOST_ASIO_DECL network_v4(const address_v4& addr,
+      unsigned short prefix_len);
+
+  /// Construct network based on the specified address and netmask.
+  BOOST_ASIO_DECL network_v4(const address_v4& addr,
+      const address_v4& mask);
+
+  /// Copy constructor.
+  network_v4(const network_v4& other) BOOST_ASIO_NOEXCEPT
+    : address_(other.address_),
+      prefix_length_(other.prefix_length_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move constructor.
+  network_v4(network_v4&& other) BOOST_ASIO_NOEXCEPT
+    : address_(BOOST_ASIO_MOVE_CAST(address_v4)(other.address_)),
+      prefix_length_(other.prefix_length_)
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Assign from another network.
+  network_v4& operator=(const network_v4& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = other.address_;
+    prefix_length_ = other.prefix_length_;
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move-assign from another network.
+  network_v4& operator=(network_v4&& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = BOOST_ASIO_MOVE_CAST(address_v4)(other.address_);
+    prefix_length_ = other.prefix_length_;
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Obtain the address object specified when the network object was created.
+  address_v4 address() const BOOST_ASIO_NOEXCEPT
+  {
+    return address_;
+  }
+
+  /// Obtain the prefix length that was specified when the network object was
+  /// created.
+  unsigned short prefix_length() const BOOST_ASIO_NOEXCEPT
+  {
+    return prefix_length_;
+  }
+
+  /// Obtain the netmask that was specified when the network object was created.
+  BOOST_ASIO_DECL address_v4 netmask() const BOOST_ASIO_NOEXCEPT;
+
+  /// Obtain an address object that represents the network address.
+  address_v4 network() const BOOST_ASIO_NOEXCEPT
+  {
+    return address_v4(address_.to_uint() & netmask().to_uint());
+  }
+
+  /// Obtain an address object that represents the network's broadcast address.
+  address_v4 broadcast() const BOOST_ASIO_NOEXCEPT
+  {
+    return address_v4(network().to_uint() | (netmask().to_uint() ^ 0xFFFFFFFF));
+  }
+
+  /// Obtain an address range corresponding to the hosts in the network.
+  BOOST_ASIO_DECL address_v4_range hosts() const BOOST_ASIO_NOEXCEPT;
+
+  /// Obtain the true network address, omitting any host bits.
+  network_v4 canonical() const BOOST_ASIO_NOEXCEPT
+  {
+    return network_v4(network(), netmask());
+  }
+
+  /// Test if network is a valid host address.
+  bool is_host() const BOOST_ASIO_NOEXCEPT
+  {
+    return prefix_length_ == 32;
+  }
+
+  /// Test if a network is a real subnet of another network.
+  BOOST_ASIO_DECL bool is_subnet_of(const network_v4& other) const;
+
+  /// Get the network as an address in dotted decimal format.
+  BOOST_ASIO_DECL std::string to_string() const;
+
+  /// Get the network as an address in dotted decimal format.
+  BOOST_ASIO_DECL std::string to_string(boost::system::error_code& ec) const;
+
+  /// Compare two networks for equality.
+  friend bool operator==(const network_v4& a, const network_v4& b)
+  {
+    return a.address_ == b.address_ && a.prefix_length_ == b.prefix_length_;
+  }
+
+  /// Compare two networks for inequality.
+  friend bool operator!=(const network_v4& a, const network_v4& b)
+  {
+    return !(a == b);
+  }
+
+private:
+  address_v4 address_;
+  unsigned short prefix_length_;
+};
+
+/// Create an IPv4 network from an address and prefix length.
+/**
+ * @relates address_v4
+ */
+inline network_v4 make_network_v4(
+    const address_v4& addr, unsigned short prefix_len)
+{
+  return network_v4(addr, prefix_len);
+}
+
+/// Create an IPv4 network from an address and netmask.
+/**
+ * @relates address_v4
+ */
+inline network_v4 make_network_v4(
+    const address_v4& addr, const address_v4& mask)
+{
+  return network_v4(addr, mask);
+}
+
+/// Create an IPv4 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v4
+ */
+BOOST_ASIO_DECL network_v4 make_network_v4(const char* str);
+
+/// Create an IPv4 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v4
+ */
+BOOST_ASIO_DECL network_v4 make_network_v4(
+    const char* str, boost::system::error_code& ec);
+
+/// Create an IPv4 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v4
+ */
+BOOST_ASIO_DECL network_v4 make_network_v4(const std::string& str);
+
+/// Create an IPv4 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v4
+ */
+BOOST_ASIO_DECL network_v4 make_network_v4(
+    const std::string& str, boost::system::error_code& ec);
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Create an IPv4 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v4
+ */
+BOOST_ASIO_DECL network_v4 make_network_v4(string_view str);
+
+/// Create an IPv4 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v4
+ */
+BOOST_ASIO_DECL network_v4 make_network_v4(
+    string_view str, boost::system::error_code& ec);
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+       //  || defined(GENERATING_DOCUMENTATION)
+
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+/// Output a network as a string.
+/**
+ * Used to output a human-readable string for a specified network.
+ *
+ * @param os The output stream to which the string will be written.
+ *
+ * @param net The network to be written.
+ *
+ * @return The output stream.
+ *
+ * @relates boost::asio::ip::address_v4
+ */
+template <typename Elem, typename Traits>
+std::basic_ostream<Elem, Traits>& operator<<(
+    std::basic_ostream<Elem, Traits>& os, const network_v4& net);
+
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/ip/impl/network_v4.hpp>
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/ip/impl/network_v4.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+#endif // BOOST_ASIO_IP_NETWORK_V4_HPP
diff --git a/include/boost/asio/ip/network_v6.hpp b/include/boost/asio/ip/network_v6.hpp
new file mode 100644
index 0000000000..83e67338e6
--- /dev/null
+++ b/include/boost/asio/ip/network_v6.hpp
@@ -0,0 +1,237 @@
+//
+// ip/network_v6.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_NETWORK_V6_HPP
+#define BOOST_ASIO_IP_NETWORK_V6_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <string>
+#include <boost/asio/detail/string_view.hpp>
+#include <boost/system/error_code.hpp>
+#include <boost/asio/ip/address_v6_range.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+/// Represents an IPv6 network.
+/**
+ * The boost::asio::ip::network_v6 class provides the ability to use and
+ * manipulate IP version 6 networks.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+class network_v6
+{
+public:
+  /// Default constructor.
+  network_v6() BOOST_ASIO_NOEXCEPT
+    : address_(),
+      prefix_length_(0)
+  {
+  }
+
+  /// Construct a network based on the specified address and prefix length.
+  BOOST_ASIO_DECL network_v6(const address_v6& addr,
+      unsigned short prefix_len);
+
+  /// Copy constructor.
+  network_v6(const network_v6& other) BOOST_ASIO_NOEXCEPT
+    : address_(other.address_),
+      prefix_length_(other.prefix_length_)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move constructor.
+  network_v6(network_v6&& other) BOOST_ASIO_NOEXCEPT
+    : address_(BOOST_ASIO_MOVE_CAST(address_v6)(other.address_)),
+      prefix_length_(other.prefix_length_)
+  {
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Assign from another network.
+  network_v6& operator=(const network_v6& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = other.address_;
+    prefix_length_ = other.prefix_length_;
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Move-assign from another network.
+  network_v6& operator=(network_v6&& other) BOOST_ASIO_NOEXCEPT
+  {
+    address_ = BOOST_ASIO_MOVE_CAST(address_v6)(other.address_);
+    prefix_length_ = other.prefix_length_;
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+  /// Obtain the address object specified when the network object was created.
+  address_v6 address() const BOOST_ASIO_NOEXCEPT
+  {
+    return address_;
+  }
+
+  /// Obtain the prefix length that was specified when the network object was
+  /// created.
+  unsigned short prefix_length() const BOOST_ASIO_NOEXCEPT
+  {
+    return prefix_length_;
+  }
+
+  /// Obtain an address object that represents the network address.
+  BOOST_ASIO_DECL address_v6 network() const BOOST_ASIO_NOEXCEPT;
+
+  /// Obtain an address range corresponding to the hosts in the network.
+  BOOST_ASIO_DECL address_v6_range hosts() const BOOST_ASIO_NOEXCEPT;
+
+  /// Obtain the true network address, omitting any host bits.
+  network_v6 canonical() const BOOST_ASIO_NOEXCEPT
+  {
+    return network_v6(network(), prefix_length());
+  }
+
+  /// Test if network is a valid host address.
+  bool is_host() const BOOST_ASIO_NOEXCEPT
+  {
+    return prefix_length_ == 128;
+  }
+
+  /// Test if a network is a real subnet of another network.
+  BOOST_ASIO_DECL bool is_subnet_of(const network_v6& other) const;
+
+  /// Get the network as an address in dotted decimal format.
+  BOOST_ASIO_DECL std::string to_string() const;
+
+  /// Get the network as an address in dotted decimal format.
+  BOOST_ASIO_DECL std::string to_string(boost::system::error_code& ec) const;
+
+  /// Compare two networks for equality.
+  friend bool operator==(const network_v6& a, const network_v6& b)
+  {
+    return a.address_ == b.address_ && a.prefix_length_ == b.prefix_length_;
+  }
+
+  /// Compare two networks for inequality.
+  friend bool operator!=(const network_v6& a, const network_v6& b)
+  {
+    return !(a == b);
+  }
+
+private:
+  address_v6 address_;
+  unsigned short prefix_length_;
+};
+
+/// Create an IPv6 network from an address and prefix length.
+/**
+ * @relates address_v6
+ */
+inline network_v6 make_network_v6(
+    const address_v6& addr, unsigned short prefix_len)
+{
+  return network_v6(addr, prefix_len);
+}
+
+/// Create an IPv6 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v6
+ */
+BOOST_ASIO_DECL network_v6 make_network_v6(const char* str);
+
+/// Create an IPv6 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v6
+ */
+BOOST_ASIO_DECL network_v6 make_network_v6(
+    const char* str, boost::system::error_code& ec);
+
+/// Create an IPv6 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v6
+ */
+BOOST_ASIO_DECL network_v6 make_network_v6(const std::string& str);
+
+/// Create an IPv6 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v6
+ */
+BOOST_ASIO_DECL network_v6 make_network_v6(
+    const std::string& str, boost::system::error_code& ec);
+
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Create an IPv6 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v6
+ */
+BOOST_ASIO_DECL network_v6 make_network_v6(string_view str);
+
+/// Create an IPv6 network from a string containing IP address and prefix
+/// length.
+/**
+ * @relates network_v6
+ */
+BOOST_ASIO_DECL network_v6 make_network_v6(
+    string_view str, boost::system::error_code& ec);
+
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+       //  || defined(GENERATING_DOCUMENTATION)
+
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+/// Output a network as a string.
+/**
+ * Used to output a human-readable string for a specified network.
+ *
+ * @param os The output stream to which the string will be written.
+ *
+ * @param net The network to be written.
+ *
+ * @return The output stream.
+ *
+ * @relates boost::asio::ip::address_v6
+ */
+template <typename Elem, typename Traits>
+std::basic_ostream<Elem, Traits>& operator<<(
+    std::basic_ostream<Elem, Traits>& os, const network_v6& net);
+
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/ip/impl/network_v6.hpp>
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/ip/impl/network_v6.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+#endif // BOOST_ASIO_IP_NETWORK_V6_HPP
diff --git a/include/boost/asio/ip/resolver_base.hpp b/include/boost/asio/ip/resolver_base.hpp
new file mode 100644
index 0000000000..596a8221dc
--- /dev/null
+++ b/include/boost/asio/ip/resolver_base.hpp
@@ -0,0 +1,131 @@
+//
+// ip/resolver_base.hpp
+// ~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IP_RESOLVER_BASE_HPP
+#define BOOST_ASIO_IP_RESOLVER_BASE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/socket_types.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace ip {
+
+/// The resolver_base class is used as a base for the basic_resolver class
+/// templates to provide a common place to define the flag constants.
+class resolver_base
+{
+public:
+#if defined(GENERATING_DOCUMENTATION)
+  /// A bitmask type (C++ Std [lib.bitmask.types]).
+  typedef unspecified flags;
+
+  /// Determine the canonical name of the host specified in the query.
+  static const flags canonical_name = implementation_defined;
+
+  /// Indicate that returned endpoint is intended for use as a locally bound
+  /// socket endpoint.
+  static const flags passive = implementation_defined;
+
+  /// Host name should be treated as a numeric string defining an IPv4 or IPv6
+  /// address and no name resolution should be attempted.
+  static const flags numeric_host = implementation_defined;
+
+  /// Service name should be treated as a numeric string defining a port number
+  /// and no name resolution should be attempted.
+  static const flags numeric_service = implementation_defined;
+
+  /// If the query protocol family is specified as IPv6, return IPv4-mapped
+  /// IPv6 addresses on finding no IPv6 addresses.
+  static const flags v4_mapped = implementation_defined;
+
+  /// If used with v4_mapped, return all matching IPv6 and IPv4 addresses.
+  static const flags all_matching = implementation_defined;
+
+  /// Only return IPv4 addresses if a non-loopback IPv4 address is configured
+  /// for the system. Only return IPv6 addresses if a non-loopback IPv6 address
+  /// is configured for the system.
+  static const flags address_configured = implementation_defined;
+#else
+  enum flags
+  {
+    canonical_name = BOOST_ASIO_OS_DEF(AI_CANONNAME),
+    passive = BOOST_ASIO_OS_DEF(AI_PASSIVE),
+    numeric_host = BOOST_ASIO_OS_DEF(AI_NUMERICHOST),
+    numeric_service = BOOST_ASIO_OS_DEF(AI_NUMERICSERV),
+    v4_mapped = BOOST_ASIO_OS_DEF(AI_V4MAPPED),
+    all_matching = BOOST_ASIO_OS_DEF(AI_ALL),
+    address_configured = BOOST_ASIO_OS_DEF(AI_ADDRCONFIG)
+  };
+
+  // Implement bitmask operations as shown in C++ Std [lib.bitmask.types].
+
+  friend flags operator&(flags x, flags y)
+  {
+    return static_cast<flags>(
+        static_cast<unsigned int>(x) & static_cast<unsigned int>(y));
+  }
+
+  friend flags operator|(flags x, flags y)
+  {
+    return static_cast<flags>(
+        static_cast<unsigned int>(x) | static_cast<unsigned int>(y));
+  }
+
+  friend flags operator^(flags x, flags y)
+  {
+    return static_cast<flags>(
+        static_cast<unsigned int>(x) ^ static_cast<unsigned int>(y));
+  }
+
+  friend flags operator~(flags x)
+  {
+    return static_cast<flags>(~static_cast<unsigned int>(x));
+  }
+
+  friend flags& operator&=(flags& x, flags y)
+  {
+    x = x & y;
+    return x;
+  }
+
+  friend flags& operator|=(flags& x, flags y)
+  {
+    x = x | y;
+    return x;
+  }
+
+  friend flags& operator^=(flags& x, flags y)
+  {
+    x = x ^ y;
+    return x;
+  }
+#endif
+
+protected:
+  /// Protected destructor to prevent deletion through this type.
+  ~resolver_base()
+  {
+  }
+};
+
+} // namespace ip
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IP_RESOLVER_BASE_HPP
diff --git a/include/boost/asio/ip/resolver_query_base.hpp b/include/boost/asio/ip/resolver_query_base.hpp
index fd74059772..99d6e29f39 100644
--- a/include/boost/asio/ip/resolver_query_base.hpp
+++ b/include/boost/asio/ip/resolver_query_base.hpp
@@ -16,7 +16,7 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/detail/socket_types.hpp>
+#include <boost/asio/ip/resolver_base.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -27,95 +27,8 @@ namespace ip {
 /// The resolver_query_base class is used as a base for the
 /// basic_resolver_query class templates to provide a common place to define
 /// the flag constants.
-class resolver_query_base
+class resolver_query_base : public resolver_base
 {
-public:
-#if defined(GENERATING_DOCUMENTATION)
-  /// A bitmask type (C++ Std [lib.bitmask.types]).
-  typedef unspecified flags;
-
-  /// Determine the canonical name of the host specified in the query.
-  static const flags canonical_name = implementation_defined;
-
-  /// Indicate that returned endpoint is intended for use as a locally bound
-  /// socket endpoint.
-  static const flags passive = implementation_defined;
-
-  /// Host name should be treated as a numeric string defining an IPv4 or IPv6
-  /// address and no name resolution should be attempted.
-  static const flags numeric_host = implementation_defined;
-
-  /// Service name should be treated as a numeric string defining a port number
-  /// and no name resolution should be attempted.
-  static const flags numeric_service = implementation_defined;
-
-  /// If the query protocol family is specified as IPv6, return IPv4-mapped
-  /// IPv6 addresses on finding no IPv6 addresses.
-  static const flags v4_mapped = implementation_defined;
-
-  /// If used with v4_mapped, return all matching IPv6 and IPv4 addresses.
-  static const flags all_matching = implementation_defined;
-
-  /// Only return IPv4 addresses if a non-loopback IPv4 address is configured
-  /// for the system. Only return IPv6 addresses if a non-loopback IPv6 address
-  /// is configured for the system.
-  static const flags address_configured = implementation_defined;
-#else
-  enum flags
-  {
-    canonical_name = BOOST_ASIO_OS_DEF(AI_CANONNAME),
-    passive = BOOST_ASIO_OS_DEF(AI_PASSIVE),
-    numeric_host = BOOST_ASIO_OS_DEF(AI_NUMERICHOST),
-    numeric_service = BOOST_ASIO_OS_DEF(AI_NUMERICSERV),
-    v4_mapped = BOOST_ASIO_OS_DEF(AI_V4MAPPED),
-    all_matching = BOOST_ASIO_OS_DEF(AI_ALL),
-    address_configured = BOOST_ASIO_OS_DEF(AI_ADDRCONFIG)
-  };
-
-  // Implement bitmask operations as shown in C++ Std [lib.bitmask.types].
-
-  friend flags operator&(flags x, flags y)
-  {
-    return static_cast<flags>(
-        static_cast<unsigned int>(x) & static_cast<unsigned int>(y));
-  }
-
-  friend flags operator|(flags x, flags y)
-  {
-    return static_cast<flags>(
-        static_cast<unsigned int>(x) | static_cast<unsigned int>(y));
-  }
-
-  friend flags operator^(flags x, flags y)
-  {
-    return static_cast<flags>(
-        static_cast<unsigned int>(x) ^ static_cast<unsigned int>(y));
-  }
-
-  friend flags operator~(flags x)
-  {
-    return static_cast<flags>(~static_cast<unsigned int>(x));
-  }
-
-  friend flags& operator&=(flags& x, flags y)
-  {
-    x = x & y;
-    return x;
-  }
-
-  friend flags& operator|=(flags& x, flags y)
-  {
-    x = x | y;
-    return x;
-  }
-
-  friend flags& operator^=(flags& x, flags y)
-  {
-    x = x ^ y;
-    return x;
-  }
-#endif
-
 protected:
   /// Protected destructor to prevent deletion through this type.
   ~resolver_query_base()
diff --git a/include/boost/asio/ip/resolver_service.hpp b/include/boost/asio/ip/resolver_service.hpp
index b4aa4d25bb..83ad490348 100644
--- a/include/boost/asio/ip/resolver_service.hpp
+++ b/include/boost/asio/ip/resolver_service.hpp
@@ -16,11 +16,15 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/async_result.hpp>
 #include <boost/system/error_code.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/basic_resolver_iterator.hpp>
 #include <boost/asio/ip/basic_resolver_query.hpp>
+#include <boost/asio/ip/basic_resolver_results.hpp>
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/winrt_resolver_service.hpp>
@@ -38,7 +42,7 @@ namespace ip {
 template <typename InternetProtocol>
 class resolver_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<
       resolver_service<InternetProtocol> >
@@ -47,7 +51,7 @@ class resolver_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The protocol type.
@@ -62,6 +66,9 @@ class resolver_service
   /// The iterator type.
   typedef basic_resolver_iterator<InternetProtocol> iterator_type;
 
+  /// The results type.
+  typedef basic_resolver_results<InternetProtocol> results_type;
+
 private:
   // The type of the platform-specific implementation.
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
@@ -80,11 +87,11 @@ class resolver_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// Construct a new resolver service for the specified io_service.
-  explicit resolver_service(boost::asio::io_service& io_service)
+  /// Construct a new resolver service for the specified io_context.
+  explicit resolver_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        resolver_service<InternetProtocol> >(io_service),
-      service_impl_(io_service)
+        resolver_service<InternetProtocol> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -94,6 +101,23 @@ class resolver_service
     service_impl_.construct(impl);
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a new resolver implementation.
+  void move_construct(implementation_type& impl,
+      implementation_type& other_impl)
+  {
+    service_impl_.move_construct(impl, other_impl);
+  }
+
+  /// Move-assign from another resolver implementation.
+  void move_assign(implementation_type& impl,
+      resolver_service& other_service,
+      implementation_type& other_impl)
+  {
+    service_impl_.move_assign(impl, other_service.service_impl_, other_impl);
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
   /// Destroy a resolver implementation.
   void destroy(implementation_type& impl)
   {
@@ -107,7 +131,7 @@ class resolver_service
   }
 
   /// Resolve a query to a list of entries.
-  iterator_type resolve(implementation_type& impl, const query_type& query,
+  results_type resolve(implementation_type& impl, const query_type& query,
       boost::system::error_code& ec)
   {
     return service_impl_.resolve(impl, query, ec);
@@ -116,21 +140,20 @@ class resolver_service
   /// Asynchronously resolve a query to a list of entries.
   template <typename ResolveHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
-      void (boost::system::error_code, iterator_type))
+      void (boost::system::error_code, results_type))
   async_resolve(implementation_type& impl, const query_type& query,
       BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      ResolveHandler, void (boost::system::error_code, iterator_type)> init(
-        BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
+    boost::asio::async_completion<ResolveHandler,
+      void (boost::system::error_code, results_type)> init(handler);
 
-    service_impl_.async_resolve(impl, query, init.handler);
+    service_impl_.async_resolve(impl, query, init.completion_handler);
 
     return init.result.get();
   }
 
   /// Resolve an endpoint to a list of entries.
-  iterator_type resolve(implementation_type& impl,
+  results_type resolve(implementation_type& impl,
       const endpoint_type& endpoint, boost::system::error_code& ec)
   {
     return service_impl_.resolve(impl, endpoint, ec);
@@ -139,30 +162,29 @@ class resolver_service
   /// Asynchronously resolve an endpoint to a list of entries.
   template <typename ResolveHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(ResolveHandler,
-      void (boost::system::error_code, iterator_type))
+      void (boost::system::error_code, results_type))
   async_resolve(implementation_type& impl, const endpoint_type& endpoint,
       BOOST_ASIO_MOVE_ARG(ResolveHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      ResolveHandler, void (boost::system::error_code, iterator_type)> init(
-        BOOST_ASIO_MOVE_CAST(ResolveHandler)(handler));
+    boost::asio::async_completion<ResolveHandler,
+      void (boost::system::error_code, results_type)> init(handler);
 
-    service_impl_.async_resolve(impl, endpoint, init.handler);
+    service_impl_.async_resolve(impl, endpoint, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // Perform any fork-related housekeeping.
-  void fork_service(boost::asio::io_service::fork_event event)
+  void notify_fork(boost::asio::io_context::fork_event event)
   {
-    service_impl_.fork_service(event);
+    service_impl_.notify_fork(event);
   }
 
   // The platform-specific implementation.
@@ -175,4 +197,6 @@ class resolver_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_IP_RESOLVER_SERVICE_HPP
diff --git a/include/boost/asio/ip/tcp.hpp b/include/boost/asio/ip/tcp.hpp
index 079ec46a25..d6bb59644b 100644
--- a/include/boost/asio/ip/tcp.hpp
+++ b/include/boost/asio/ip/tcp.hpp
@@ -100,7 +100,7 @@ class tcp
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::ip::tcp::no_delay option(true);
    * socket.set_option(option);
@@ -109,7 +109,7 @@ class tcp
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::ip::tcp::no_delay option;
    * socket.get_option(option);
diff --git a/include/boost/asio/ip/unicast.hpp b/include/boost/asio/ip/unicast.hpp
index 4a9df8bfd2..809bcacc85 100644
--- a/include/boost/asio/ip/unicast.hpp
+++ b/include/boost/asio/ip/unicast.hpp
@@ -33,7 +33,7 @@ namespace unicast {
  * @par Examples
  * Setting the option:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::unicast::hops option(4);
  * socket.set_option(option);
@@ -42,7 +42,7 @@ namespace unicast {
  * @par
  * Getting the current option value:
  * @code
- * boost::asio::ip::udp::socket socket(io_service); 
+ * boost::asio::ip::udp::socket socket(io_context); 
  * ...
  * boost::asio::ip::unicast::hops option;
  * socket.get_option(option);
diff --git a/include/boost/asio/ip/v6_only.hpp b/include/boost/asio/ip/v6_only.hpp
index b22c9a5db8..5dc6ff0874 100644
--- a/include/boost/asio/ip/v6_only.hpp
+++ b/include/boost/asio/ip/v6_only.hpp
@@ -32,7 +32,7 @@ namespace ip {
  * @par Examples
  * Setting the option:
  * @code
- * boost::asio::ip::tcp::socket socket(io_service); 
+ * boost::asio::ip::tcp::socket socket(io_context); 
  * ...
  * boost::asio::ip::v6_only option(true);
  * socket.set_option(option);
@@ -41,7 +41,7 @@ namespace ip {
  * @par
  * Getting the current option value:
  * @code
- * boost::asio::ip::tcp::socket socket(io_service); 
+ * boost::asio::ip::tcp::socket socket(io_context); 
  * ...
  * boost::asio::ip::v6_only option;
  * socket.get_option(option);
diff --git a/include/boost/asio/is_executor.hpp b/include/boost/asio/is_executor.hpp
new file mode 100644
index 0000000000..4983c5385c
--- /dev/null
+++ b/include/boost/asio/is_executor.hpp
@@ -0,0 +1,48 @@
+//
+// is_executor.hpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_IS_EXECUTOR_HPP
+#define BOOST_ASIO_IS_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/is_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// The is_executor trait detects whether a type T meets the Executor type
+/// requirements.
+/**
+ * Class template @c is_executor is a UnaryTypeTrait that is derived from @c
+ * true_type if the type @c T meets the syntactic requirements for Executor,
+ * otherwise @c false_type.
+ */
+template <typename T>
+struct is_executor
+#if defined(GENERATING_DOCUMENTATION)
+  : integral_constant<bool, automatically_determined>
+#else // defined(GENERATING_DOCUMENTATION)
+  : boost::asio::detail::is_executor<T>
+#endif // defined(GENERATING_DOCUMENTATION)
+{
+};
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IS_EXECUTOR_HPP
diff --git a/include/boost/asio/local/connect_pair.hpp b/include/boost/asio/local/connect_pair.hpp
index 333c758783..18417856c7 100644
--- a/include/boost/asio/local/connect_pair.hpp
+++ b/include/boost/asio/local/connect_pair.hpp
@@ -33,32 +33,32 @@ namespace asio {
 namespace local {
 
 /// Create a pair of connected sockets.
-template <typename Protocol, typename SocketService1, typename SocketService2>
+template <typename Protocol BOOST_ASIO_SVC_TPARAM BOOST_ASIO_SVC_TPARAM1>
 void connect_pair(
-    basic_socket<Protocol, SocketService1>& socket1,
-    basic_socket<Protocol, SocketService2>& socket2);
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket1,
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG1>& socket2);
 
 /// Create a pair of connected sockets.
-template <typename Protocol, typename SocketService1, typename SocketService2>
-boost::system::error_code connect_pair(
-    basic_socket<Protocol, SocketService1>& socket1,
-    basic_socket<Protocol, SocketService2>& socket2,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM BOOST_ASIO_SVC_TPARAM1>
+BOOST_ASIO_SYNC_OP_VOID connect_pair(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket1,
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG1>& socket2,
     boost::system::error_code& ec);
 
-template <typename Protocol, typename SocketService1, typename SocketService2>
+template <typename Protocol BOOST_ASIO_SVC_TPARAM BOOST_ASIO_SVC_TPARAM1>
 inline void connect_pair(
-    basic_socket<Protocol, SocketService1>& socket1,
-    basic_socket<Protocol, SocketService2>& socket2)
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket1,
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG1>& socket2)
 {
   boost::system::error_code ec;
   connect_pair(socket1, socket2, ec);
   boost::asio::detail::throw_error(ec, "connect_pair");
 }
 
-template <typename Protocol, typename SocketService1, typename SocketService2>
-inline boost::system::error_code connect_pair(
-    basic_socket<Protocol, SocketService1>& socket1,
-    basic_socket<Protocol, SocketService2>& socket2,
+template <typename Protocol BOOST_ASIO_SVC_TPARAM BOOST_ASIO_SVC_TPARAM1>
+inline BOOST_ASIO_SYNC_OP_VOID connect_pair(
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG>& socket1,
+    basic_socket<Protocol BOOST_ASIO_SVC_TARG1>& socket2,
     boost::system::error_code& ec)
 {
   // Check that this function is only being used with a UNIX domain socket.
@@ -71,27 +71,29 @@ inline boost::system::error_code connect_pair(
   if (boost::asio::detail::socket_ops::socketpair(protocol.family(),
         protocol.type(), protocol.protocol(), sv, ec)
       == boost::asio::detail::socket_error_retval)
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 
-  if (socket1.assign(protocol, sv[0], ec))
+  socket1.assign(protocol, sv[0], ec);
+  if (ec)
   {
     boost::system::error_code temp_ec;
     boost::asio::detail::socket_ops::state_type state[2] = { 0, 0 };
     boost::asio::detail::socket_ops::close(sv[0], state[0], true, temp_ec);
     boost::asio::detail::socket_ops::close(sv[1], state[1], true, temp_ec);
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  if (socket2.assign(protocol, sv[1], ec))
+  socket2.assign(protocol, sv[1], ec);
+  if (ec)
   {
     boost::system::error_code temp_ec;
     socket1.close(temp_ec);
     boost::asio::detail::socket_ops::state_type state = 0;
     boost::asio::detail::socket_ops::close(sv[1], state, true, temp_ec);
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 } // namespace local
diff --git a/include/boost/asio/packaged_task.hpp b/include/boost/asio/packaged_task.hpp
new file mode 100644
index 0000000000..586de13b7b
--- /dev/null
+++ b/include/boost/asio/packaged_task.hpp
@@ -0,0 +1,128 @@
+//
+// packaged_task.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_PACKAGED_TASK_HPP
+#define BOOST_ASIO_PACKAGED_TASK_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_STD_FUTURE) \
+  || defined(GENERATING_DOCUMENTATION)
+
+#include <future>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/detail/variadic_templates.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+#if defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Partial specialisation of @c async_result for @c std::packaged_task.
+template <typename Result, typename... Args, typename Signature>
+class async_result<std::packaged_task<Result(Args...)>, Signature>
+{
+public:
+  /// The packaged task is the concrete completion handler type.
+  typedef std::packaged_task<Result(Args...)> completion_handler_type;
+
+  /// The return type of the initiating function is the future obtained from
+  /// the packaged task.
+  typedef std::future<Result> return_type;
+
+  /// The constructor extracts the future from the packaged task.
+  explicit async_result(completion_handler_type& h)
+    : future_(h.get_future())
+  {
+  }
+
+  /// Returns the packaged task's future.
+  return_type get()
+  {
+    return std::move(future_);
+  }
+
+private:
+  return_type future_;
+};
+
+#else // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+      //   || defined(GENERATING_DOCUMENTATION)
+
+template <typename Result, typename Signature>
+struct async_result<std::packaged_task<Result()>, Signature>
+{
+  typedef std::packaged_task<Result()> completion_handler_type;
+  typedef std::future<Result> return_type;
+
+  explicit async_result(completion_handler_type& h)
+    : future_(h.get_future())
+  {
+  }
+
+  return_type get()
+  {
+    return std::move(future_);
+  }
+
+private:
+  return_type future_;
+};
+
+#define BOOST_ASIO_PRIVATE_ASYNC_RESULT_DEF(n) \
+  template <typename Result, \
+    BOOST_ASIO_VARIADIC_TPARAMS(n), typename Signature> \
+  class async_result< \
+    std::packaged_task<Result(BOOST_ASIO_VARIADIC_TARGS(n))>, Signature> \
+  { \
+  public: \
+    typedef std::packaged_task< \
+      Result(BOOST_ASIO_VARIADIC_TARGS(n))> \
+        completion_handler_type; \
+  \
+    typedef std::future<Result> return_type; \
+  \
+    explicit async_result(completion_handler_type& h) \
+      : future_(h.get_future()) \
+    { \
+    } \
+  \
+    return_type get() \
+    { \
+      return std::move(future_); \
+    } \
+  \
+  private: \
+    return_type future_; \
+  }; \
+  /**/
+  BOOST_ASIO_VARIADIC_GENERATE(BOOST_ASIO_PRIVATE_ASYNC_RESULT_DEF)
+#undef BOOST_ASIO_PRIVATE_ASYNC_RESULT_DEF
+
+#endif // defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
+       //   || defined(GENERATING_DOCUMENTATION)
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // defined(BOOST_ASIO_HAS_STD_FUTURE)
+       //   || defined(GENERATING_DOCUMENTATION)
+
+#endif // BOOST_ASIO_PACKAGED_TASK_HPP
diff --git a/include/boost/asio/placeholders.hpp b/include/boost/asio/placeholders.hpp
index 8714e3454a..0bc72769a1 100644
--- a/include/boost/asio/placeholders.hpp
+++ b/include/boost/asio/placeholders.hpp
@@ -41,9 +41,19 @@ unspecified bytes_transferred;
 
 /// An argument placeholder, for use with boost::bind(), that corresponds to
 /// the iterator argument of a handler for asynchronous functions such as
-/// boost::asio::basic_resolver::async_resolve.
+/// boost::asio::async_connect.
 unspecified iterator;
 
+/// An argument placeholder, for use with boost::bind(), that corresponds to
+/// the results argument of a handler for asynchronous functions such as
+/// boost::asio::basic_resolver::async_resolve.
+unspecified results;
+
+/// An argument placeholder, for use with boost::bind(), that corresponds to
+/// the results argument of a handler for asynchronous functions such as
+/// boost::asio::async_connect.
+unspecified endpoint;
+
 /// An argument placeholder, for use with boost::bind(), that corresponds to
 /// the signal_number argument of a handler for asynchronous functions such as
 /// boost::asio::signal_set::async_wait.
@@ -67,6 +77,16 @@ inline boost::arg<2> iterator()
   return boost::arg<2>();
 }
 
+inline boost::arg<2> results()
+{
+  return boost::arg<2>();
+}
+
+inline boost::arg<2> endpoint()
+{
+  return boost::arg<2>();
+}
+
 inline boost::arg<2> signal_number()
 {
   return boost::arg<2>();
@@ -95,6 +115,10 @@ static boost::arg<2>& bytes_transferred
   = boost::asio::placeholders::detail::placeholder<2>::get();
 static boost::arg<2>& iterator
   = boost::asio::placeholders::detail::placeholder<2>::get();
+static boost::arg<2>& results
+  = boost::asio::placeholders::detail::placeholder<2>::get();
+static boost::arg<2>& endpoint
+  = boost::asio::placeholders::detail::placeholder<2>::get();
 static boost::arg<2>& signal_number
   = boost::asio::placeholders::detail::placeholder<2>::get();
 
@@ -108,6 +132,10 @@ namespace
     = boost::asio::placeholders::detail::placeholder<2>::get();
   boost::arg<2>& iterator
     = boost::asio::placeholders::detail::placeholder<2>::get();
+  boost::arg<2>& results
+    = boost::asio::placeholders::detail::placeholder<2>::get();
+  boost::arg<2>& endpoint
+    = boost::asio::placeholders::detail::placeholder<2>::get();
   boost::arg<2>& signal_number
     = boost::asio::placeholders::detail::placeholder<2>::get();
 } // namespace
diff --git a/include/boost/asio/posix/basic_descriptor.hpp b/include/boost/asio/posix/basic_descriptor.hpp
index a857c237a3..2bb8a04efa 100644
--- a/include/boost/asio/posix/basic_descriptor.hpp
+++ b/include/boost/asio/posix/basic_descriptor.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -46,10 +48,6 @@ class basic_descriptor
     public descriptor_base
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// descriptor.
-  typedef typename DescriptorService::native_handle_type native_type;
-
   /// The native representation of a descriptor.
   typedef typename DescriptorService::native_handle_type native_handle_type;
 
@@ -60,12 +58,12 @@ class basic_descriptor
   /**
    * This constructor creates a descriptor without opening it.
    *
-   * @param io_service The io_service object that the descriptor will use to
+   * @param io_context The io_context object that the descriptor will use to
    * dispatch handlers for any asynchronous operations performed on the
    * descriptor.
    */
-  explicit basic_descriptor(boost::asio::io_service& io_service)
-    : basic_io_object<DescriptorService>(io_service)
+  explicit basic_descriptor(boost::asio::io_context& io_context)
+    : basic_io_object<DescriptorService>(io_context)
   {
   }
 
@@ -74,7 +72,7 @@ class basic_descriptor
    * This constructor creates a descriptor object to hold an existing native
    * descriptor.
    *
-   * @param io_service The io_service object that the descriptor will use to
+   * @param io_context The io_context object that the descriptor will use to
    * dispatch handlers for any asynchronous operations performed on the
    * descriptor.
    *
@@ -82,9 +80,9 @@ class basic_descriptor
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_descriptor(boost::asio::io_service& io_service,
+  basic_descriptor(boost::asio::io_context& io_context,
       const native_handle_type& native_descriptor)
-    : basic_io_object<DescriptorService>(io_service)
+    : basic_io_object<DescriptorService>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().assign(this->get_implementation(),
@@ -101,7 +99,7 @@ class basic_descriptor
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_descriptor(io_service&) constructor.
+   * constructed using the @c basic_descriptor(io_context&) constructor.
    */
   basic_descriptor(basic_descriptor&& other)
     : basic_io_object<DescriptorService>(
@@ -117,7 +115,7 @@ class basic_descriptor
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_descriptor(io_service&) constructor.
+   * constructed using the @c basic_descriptor(io_context&) constructor.
    */
   basic_descriptor& operator=(basic_descriptor&& other)
   {
@@ -179,17 +177,18 @@ class basic_descriptor
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code assign(const native_handle_type& native_descriptor,
+  BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& native_descriptor,
       boost::system::error_code& ec)
   {
-    return this->get_service().assign(
+    this->get_service().assign(
         this->get_implementation(), native_descriptor, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the descriptor is open.
   bool is_open() const
   {
-    return this->get_service().is_open(this->implementation);
+    return this->get_service().is_open(this->get_implementation());
   }
 
   /// Close the descriptor.
@@ -217,21 +216,10 @@ class basic_descriptor
    * @param ec Set to indicate what error occurred, if any. Note that, even if
    * the function indicates an error, the underlying descriptor is closed.
    */
-  boost::system::error_code close(boost::system::error_code& ec)
-  {
-    return this->get_service().close(this->get_implementation(), ec);
-  }
-
-  /// (Deprecated: Use native_handle().) Get the native descriptor
-  /// representation.
-  /**
-   * This function may be used to obtain the underlying representation of the
-   * descriptor. This is intended to allow access to native descriptor
-   * functionality that is not otherwise provided.
-   */
-  native_type native()
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return this->get_service().native_handle(this->implementation);
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native descriptor representation.
@@ -242,7 +230,7 @@ class basic_descriptor
    */
   native_handle_type native_handle()
   {
-    return this->get_service().native_handle(this->implementation);
+    return this->get_service().native_handle(this->get_implementation());
   }
 
   /// Release ownership of the native descriptor implementation.
@@ -257,7 +245,7 @@ class basic_descriptor
    */
   native_handle_type release()
   {
-    return this->get_service().release(this->implementation);
+    return this->get_service().release(this->get_implementation());
   }
 
   /// Cancel all asynchronous operations associated with the descriptor.
@@ -283,9 +271,10 @@ class basic_descriptor
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code cancel(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
-    return this->get_service().cancel(this->get_implementation(), ec);
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the descriptor.
@@ -303,7 +292,7 @@ class basic_descriptor
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
-   * boost::asio::posix::stream_descriptor descriptor(io_service);
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
    * ...
    * boost::asio::posix::stream_descriptor::bytes_readable command;
    * descriptor.io_control(command);
@@ -333,7 +322,7 @@ class basic_descriptor
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
-   * boost::asio::posix::stream_descriptor descriptor(io_service);
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
    * ...
    * boost::asio::posix::stream_descriptor::bytes_readable command;
    * boost::system::error_code ec;
@@ -346,11 +335,11 @@ class basic_descriptor
    * @endcode
    */
   template <typename IoControlCommand>
-  boost::system::error_code io_control(IoControlCommand& command,
+  BOOST_ASIO_SYNC_OP_VOID io_control(IoControlCommand& command,
       boost::system::error_code& ec)
   {
-    return this->get_service().io_control(
-        this->get_implementation(), command, ec);
+    this->get_service().io_control(this->get_implementation(), command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the descriptor.
@@ -366,7 +355,7 @@ class basic_descriptor
    */
   bool non_blocking() const
   {
-    return this->get_service().non_blocking(this->implementation);
+    return this->get_service().non_blocking(this->get_implementation());
   }
 
   /// Sets the non-blocking mode of the descriptor.
@@ -402,11 +391,11 @@ class basic_descriptor
    * operations. Asynchronous operations will never fail with the error
    * boost::asio::error::would_block.
    */
-  boost::system::error_code non_blocking(
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(
       bool mode, boost::system::error_code& ec)
   {
-    return this->get_service().non_blocking(
-        this->get_implementation(), mode, ec);
+    this->get_service().non_blocking(this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native descriptor implementation.
@@ -425,7 +414,8 @@ class basic_descriptor
    */
   bool native_non_blocking() const
   {
-    return this->get_service().native_non_blocking(this->implementation);
+    return this->get_service().native_non_blocking(
+        this->get_implementation());
   }
 
   /// Sets the non-blocking mode of the native descriptor implementation.
@@ -466,11 +456,111 @@ class basic_descriptor
    * function fails with boost::asio::error::invalid_argument, as the
    * combination does not make sense.
    */
-  boost::system::error_code native_non_blocking(
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(
       bool mode, boost::system::error_code& ec)
   {
-    return this->get_service().native_non_blocking(
+    this->get_service().native_non_blocking(
         this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the descriptor to become ready to read, ready to write, or to
+  /// have pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for a descriptor to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired descriptor state.
+   *
+   * @par Example
+   * Waiting for a descriptor to become readable.
+   * @code
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * descriptor.wait(boost::asio::posix::stream_descriptor::wait_read);
+   * @endcode
+   */
+  void wait(wait_type w)
+  {
+    boost::system::error_code ec;
+    this->get_service().wait(this->get_implementation(), w, ec);
+    boost::asio::detail::throw_error(ec, "wait");
+  }
+
+  /// Wait for the descriptor to become ready to read, ready to write, or to
+  /// have pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for a descriptor to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired descriptor state.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @par Example
+   * Waiting for a descriptor to become readable.
+   * @code
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * boost::system::error_code ec;
+   * descriptor.wait(boost::asio::posix::stream_descriptor::wait_read, ec);
+   * @endcode
+   */
+  BOOST_ASIO_SYNC_OP_VOID wait(wait_type w, boost::system::error_code& ec)
+  {
+    this->get_service().wait(this->get_implementation(), w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the descriptor to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  /**
+   * This function is used to perform an asynchronous wait for a descriptor to
+   * enter a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired descriptor state.
+   *
+   * @param handler The handler to be called when the wait operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error // Result of operation
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void wait_handler(const boost::system::error_code& error)
+   * {
+   *   if (!error)
+   *   {
+   *     // Wait succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * descriptor.async_wait(
+   *     boost::asio::posix::stream_descriptor::wait_read,
+   *     wait_handler);
+   * @endcode
+   */
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(wait_type w, BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WaitHandler.
+    BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
+
+    return this->get_service().async_wait(this->get_implementation(),
+        w, BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
   }
 
 protected:
@@ -489,4 +579,6 @@ class basic_descriptor
 #endif // defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_POSIX_BASIC_DESCRIPTOR_HPP
diff --git a/include/boost/asio/posix/basic_stream_descriptor.hpp b/include/boost/asio/posix/basic_stream_descriptor.hpp
index 4baacb519b..ca88e31159 100644
--- a/include/boost/asio/posix/basic_stream_descriptor.hpp
+++ b/include/boost/asio/posix/basic_stream_descriptor.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -50,10 +52,6 @@ class basic_stream_descriptor
   : public basic_descriptor<StreamDescriptorService>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// descriptor.
-  typedef typename StreamDescriptorService::native_handle_type native_type;
-
   /// The native representation of a descriptor.
   typedef typename StreamDescriptorService::native_handle_type
     native_handle_type;
@@ -64,12 +62,12 @@ class basic_stream_descriptor
    * descriptor needs to be opened and then connected or accepted before data
    * can be sent or received on it.
    *
-   * @param io_service The io_service object that the stream descriptor will
+   * @param io_context The io_context object that the stream descriptor will
    * use to dispatch handlers for any asynchronous operations performed on the
    * descriptor.
    */
-  explicit basic_stream_descriptor(boost::asio::io_service& io_service)
-    : basic_descriptor<StreamDescriptorService>(io_service)
+  explicit basic_stream_descriptor(boost::asio::io_context& io_context)
+    : basic_descriptor<StreamDescriptorService>(io_context)
   {
   }
 
@@ -78,7 +76,7 @@ class basic_stream_descriptor
    * This constructor creates a stream descriptor object to hold an existing
    * native descriptor.
    *
-   * @param io_service The io_service object that the stream descriptor will
+   * @param io_context The io_context object that the stream descriptor will
    * use to dispatch handlers for any asynchronous operations performed on the
    * descriptor.
    *
@@ -86,9 +84,9 @@ class basic_stream_descriptor
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_stream_descriptor(boost::asio::io_service& io_service,
+  basic_stream_descriptor(boost::asio::io_context& io_context,
       const native_handle_type& native_descriptor)
-    : basic_descriptor<StreamDescriptorService>(io_service, native_descriptor)
+    : basic_descriptor<StreamDescriptorService>(io_context, native_descriptor)
   {
   }
 
@@ -101,7 +99,7 @@ class basic_stream_descriptor
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_descriptor(io_service&) constructor.
+   * constructed using the @c basic_stream_descriptor(io_context&) constructor.
    */
   basic_stream_descriptor(basic_stream_descriptor&& other)
     : basic_descriptor<StreamDescriptorService>(
@@ -118,7 +116,7 @@ class basic_stream_descriptor
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_descriptor(io_service&) constructor.
+   * constructed using the @c basic_stream_descriptor(io_context&) constructor.
    */
   basic_stream_descriptor& operator=(basic_stream_descriptor&& other)
   {
@@ -209,7 +207,7 @@ class basic_stream_descriptor
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The write operation may not transmit all of the data to the peer.
    * Consider using the @ref async_write function if you need to ensure that all
@@ -321,7 +319,7 @@ class basic_stream_descriptor
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The read operation may not read all of the requested number of bytes.
    * Consider using the @ref async_read function if you need to ensure that the
@@ -361,4 +359,6 @@ class basic_stream_descriptor
 #endif // defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_POSIX_BASIC_STREAM_DESCRIPTOR_HPP
diff --git a/include/boost/asio/posix/descriptor.hpp b/include/boost/asio/posix/descriptor.hpp
new file mode 100644
index 0000000000..be67663eb6
--- /dev/null
+++ b/include/boost/asio/posix/descriptor.hpp
@@ -0,0 +1,646 @@
+//
+// posix/descriptor.hpp
+// ~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_POSIX_DESCRIPTOR_HPP
+#define BOOST_ASIO_POSIX_DESCRIPTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#if defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR) \
+  || defined(GENERATING_DOCUMENTATION)
+
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/basic_io_object.hpp>
+#include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/reactive_descriptor_service.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/posix/descriptor_base.hpp>
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#define BOOST_ASIO_SVC_T boost::asio::detail::reactive_descriptor_service
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace posix {
+
+/// Provides POSIX descriptor functionality.
+/**
+ * The posix::descriptor class template provides the ability to wrap a
+ * POSIX descriptor.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+class descriptor
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>,
+    public descriptor_base
+{
+public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
+  /// The native representation of a descriptor.
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef BOOST_ASIO_SVC_T::native_handle_type native_handle_type;
+#endif
+
+  /// A descriptor is always the lowest layer.
+  typedef descriptor lowest_layer_type;
+
+  /// Construct a descriptor without opening it.
+  /**
+   * This constructor creates a descriptor without opening it.
+   *
+   * @param io_context The io_context object that the descriptor will use to
+   * dispatch handlers for any asynchronous operations performed on the
+   * descriptor.
+   */
+  explicit descriptor(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+  }
+
+  /// Construct a descriptor on an existing native descriptor.
+  /**
+   * This constructor creates a descriptor object to hold an existing native
+   * descriptor.
+   *
+   * @param io_context The io_context object that the descriptor will use to
+   * dispatch handlers for any asynchronous operations performed on the
+   * descriptor.
+   *
+   * @param native_descriptor A native descriptor.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  descriptor(boost::asio::io_context& io_context,
+      const native_handle_type& native_descriptor)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(),
+        native_descriptor, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a descriptor from another.
+  /**
+   * This constructor moves a descriptor from one object to another.
+   *
+   * @param other The other descriptor object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c descriptor(io_context&) constructor.
+   */
+  descriptor(descriptor&& other)
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
+  {
+  }
+
+  /// Move-assign a descriptor from another.
+  /**
+   * This assignment operator moves a descriptor from one object to another.
+   *
+   * @param other The other descriptor object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c descriptor(io_context&) constructor.
+   */
+  descriptor& operator=(descriptor&& other)
+  {
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+
+  /// Get a reference to the lowest layer.
+  /**
+   * This function returns a reference to the lowest layer in a stack of
+   * layers. Since a descriptor cannot contain any further layers, it
+   * simply returns a reference to itself.
+   *
+   * @return A reference to the lowest layer in the stack of layers. Ownership
+   * is not transferred to the caller.
+   */
+  lowest_layer_type& lowest_layer()
+  {
+    return *this;
+  }
+
+  /// Get a const reference to the lowest layer.
+  /**
+   * This function returns a const reference to the lowest layer in a stack of
+   * layers. Since a descriptor cannot contain any further layers, it
+   * simply returns a reference to itself.
+   *
+   * @return A const reference to the lowest layer in the stack of layers.
+   * Ownership is not transferred to the caller.
+   */
+  const lowest_layer_type& lowest_layer() const
+  {
+    return *this;
+  }
+
+  /// Assign an existing native descriptor to the descriptor.
+  /*
+   * This function opens the descriptor to hold an existing native descriptor.
+   *
+   * @param native_descriptor A native descriptor.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void assign(const native_handle_type& native_descriptor)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(),
+        native_descriptor, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+  /// Assign an existing native descriptor to the descriptor.
+  /*
+   * This function opens the descriptor to hold an existing native descriptor.
+   *
+   * @param native_descriptor A native descriptor.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& native_descriptor,
+      boost::system::error_code& ec)
+  {
+    this->get_service().assign(
+        this->get_implementation(), native_descriptor, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Determine whether the descriptor is open.
+  bool is_open() const
+  {
+    return this->get_service().is_open(this->get_implementation());
+  }
+
+  /// Close the descriptor.
+  /**
+   * This function is used to close the descriptor. Any asynchronous read or
+   * write operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure. Note that, even if
+   * the function indicates an error, the underlying descriptor is closed.
+   */
+  void close()
+  {
+    boost::system::error_code ec;
+    this->get_service().close(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "close");
+  }
+
+  /// Close the descriptor.
+  /**
+   * This function is used to close the descriptor. Any asynchronous read or
+   * write operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any. Note that, even if
+   * the function indicates an error, the underlying descriptor is closed.
+   */
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
+  {
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Get the native descriptor representation.
+  /**
+   * This function may be used to obtain the underlying representation of the
+   * descriptor. This is intended to allow access to native descriptor
+   * functionality that is not otherwise provided.
+   */
+  native_handle_type native_handle()
+  {
+    return this->get_service().native_handle(this->get_implementation());
+  }
+
+  /// Release ownership of the native descriptor implementation.
+  /**
+   * This function may be used to obtain the underlying representation of the
+   * descriptor. After calling this function, @c is_open() returns false. The
+   * caller is responsible for closing the descriptor.
+   *
+   * All outstanding asynchronous read or write operations will finish
+   * immediately, and the handlers for cancelled operations will be passed the
+   * boost::asio::error::operation_aborted error.
+   */
+  native_handle_type release()
+  {
+    return this->get_service().release(this->get_implementation());
+  }
+
+  /// Cancel all asynchronous operations associated with the descriptor.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void cancel()
+  {
+    boost::system::error_code ec;
+    this->get_service().cancel(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "cancel");
+  }
+
+  /// Cancel all asynchronous operations associated with the descriptor.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
+  {
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Perform an IO control command on the descriptor.
+  /**
+   * This function is used to execute an IO control command on the descriptor.
+   *
+   * @param command The IO control command to be performed on the descriptor.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @sa IoControlCommand @n
+   * boost::asio::posix::descriptor_base::bytes_readable @n
+   * boost::asio::posix::descriptor_base::non_blocking_io
+   *
+   * @par Example
+   * Getting the number of bytes ready to read:
+   * @code
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * boost::asio::posix::stream_descriptor::bytes_readable command;
+   * descriptor.io_control(command);
+   * std::size_t bytes_readable = command.get();
+   * @endcode
+   */
+  template <typename IoControlCommand>
+  void io_control(IoControlCommand& command)
+  {
+    boost::system::error_code ec;
+    this->get_service().io_control(this->get_implementation(), command, ec);
+    boost::asio::detail::throw_error(ec, "io_control");
+  }
+
+  /// Perform an IO control command on the descriptor.
+  /**
+   * This function is used to execute an IO control command on the descriptor.
+   *
+   * @param command The IO control command to be performed on the descriptor.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @sa IoControlCommand @n
+   * boost::asio::posix::descriptor_base::bytes_readable @n
+   * boost::asio::posix::descriptor_base::non_blocking_io
+   *
+   * @par Example
+   * Getting the number of bytes ready to read:
+   * @code
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * boost::asio::posix::stream_descriptor::bytes_readable command;
+   * boost::system::error_code ec;
+   * descriptor.io_control(command, ec);
+   * if (ec)
+   * {
+   *   // An error occurred.
+   * }
+   * std::size_t bytes_readable = command.get();
+   * @endcode
+   */
+  template <typename IoControlCommand>
+  BOOST_ASIO_SYNC_OP_VOID io_control(IoControlCommand& command,
+      boost::system::error_code& ec)
+  {
+    this->get_service().io_control(this->get_implementation(), command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Gets the non-blocking mode of the descriptor.
+  /**
+   * @returns @c true if the descriptor's synchronous operations will fail with
+   * boost::asio::error::would_block if they are unable to perform the requested
+   * operation immediately. If @c false, synchronous operations will block
+   * until complete.
+   *
+   * @note The non-blocking mode has no effect on the behaviour of asynchronous
+   * operations. Asynchronous operations will never fail with the error
+   * boost::asio::error::would_block.
+   */
+  bool non_blocking() const
+  {
+    return this->get_service().non_blocking(this->get_implementation());
+  }
+
+  /// Sets the non-blocking mode of the descriptor.
+  /**
+   * @param mode If @c true, the descriptor's synchronous operations will fail
+   * with boost::asio::error::would_block if they are unable to perform the
+   * requested operation immediately. If @c false, synchronous operations will
+   * block until complete.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note The non-blocking mode has no effect on the behaviour of asynchronous
+   * operations. Asynchronous operations will never fail with the error
+   * boost::asio::error::would_block.
+   */
+  void non_blocking(bool mode)
+  {
+    boost::system::error_code ec;
+    this->get_service().non_blocking(this->get_implementation(), mode, ec);
+    boost::asio::detail::throw_error(ec, "non_blocking");
+  }
+
+  /// Sets the non-blocking mode of the descriptor.
+  /**
+   * @param mode If @c true, the descriptor's synchronous operations will fail
+   * with boost::asio::error::would_block if they are unable to perform the
+   * requested operation immediately. If @c false, synchronous operations will
+   * block until complete.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @note The non-blocking mode has no effect on the behaviour of asynchronous
+   * operations. Asynchronous operations will never fail with the error
+   * boost::asio::error::would_block.
+   */
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(
+      bool mode, boost::system::error_code& ec)
+  {
+    this->get_service().non_blocking(this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Gets the non-blocking mode of the native descriptor implementation.
+  /**
+   * This function is used to retrieve the non-blocking mode of the underlying
+   * native descriptor. This mode has no effect on the behaviour of the
+   * descriptor object's synchronous operations.
+   *
+   * @returns @c true if the underlying descriptor is in non-blocking mode and
+   * direct system calls may fail with boost::asio::error::would_block (or the
+   * equivalent system error).
+   *
+   * @note The current non-blocking mode is cached by the descriptor object.
+   * Consequently, the return value may be incorrect if the non-blocking mode
+   * was set directly on the native descriptor.
+   */
+  bool native_non_blocking() const
+  {
+    return this->get_service().native_non_blocking(
+        this->get_implementation());
+  }
+
+  /// Sets the non-blocking mode of the native descriptor implementation.
+  /**
+   * This function is used to modify the non-blocking mode of the underlying
+   * native descriptor. It has no effect on the behaviour of the descriptor
+   * object's synchronous operations.
+   *
+   * @param mode If @c true, the underlying descriptor is put into non-blocking
+   * mode and direct system calls may fail with boost::asio::error::would_block
+   * (or the equivalent system error).
+   *
+   * @throws boost::system::system_error Thrown on failure. If the @c mode is
+   * @c false, but the current value of @c non_blocking() is @c true, this
+   * function fails with boost::asio::error::invalid_argument, as the
+   * combination does not make sense.
+   */
+  void native_non_blocking(bool mode)
+  {
+    boost::system::error_code ec;
+    this->get_service().native_non_blocking(
+        this->get_implementation(), mode, ec);
+    boost::asio::detail::throw_error(ec, "native_non_blocking");
+  }
+
+  /// Sets the non-blocking mode of the native descriptor implementation.
+  /**
+   * This function is used to modify the non-blocking mode of the underlying
+   * native descriptor. It has no effect on the behaviour of the descriptor
+   * object's synchronous operations.
+   *
+   * @param mode If @c true, the underlying descriptor is put into non-blocking
+   * mode and direct system calls may fail with boost::asio::error::would_block
+   * (or the equivalent system error).
+   *
+   * @param ec Set to indicate what error occurred, if any. If the @c mode is
+   * @c false, but the current value of @c non_blocking() is @c true, this
+   * function fails with boost::asio::error::invalid_argument, as the
+   * combination does not make sense.
+   */
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(
+      bool mode, boost::system::error_code& ec)
+  {
+    this->get_service().native_non_blocking(
+        this->get_implementation(), mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the descriptor to become ready to read, ready to write, or to
+  /// have pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for a descriptor to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired descriptor state.
+   *
+   * @par Example
+   * Waiting for a descriptor to become readable.
+   * @code
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * descriptor.wait(boost::asio::posix::stream_descriptor::wait_read);
+   * @endcode
+   */
+  void wait(wait_type w)
+  {
+    boost::system::error_code ec;
+    this->get_service().wait(this->get_implementation(), w, ec);
+    boost::asio::detail::throw_error(ec, "wait");
+  }
+
+  /// Wait for the descriptor to become ready to read, ready to write, or to
+  /// have pending error conditions.
+  /**
+   * This function is used to perform a blocking wait for a descriptor to enter
+   * a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired descriptor state.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @par Example
+   * Waiting for a descriptor to become readable.
+   * @code
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * boost::system::error_code ec;
+   * descriptor.wait(boost::asio::posix::stream_descriptor::wait_read, ec);
+   * @endcode
+   */
+  BOOST_ASIO_SYNC_OP_VOID wait(wait_type w, boost::system::error_code& ec)
+  {
+    this->get_service().wait(this->get_implementation(), w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the descriptor to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  /**
+   * This function is used to perform an asynchronous wait for a descriptor to
+   * enter a ready to read, write or error condition state.
+   *
+   * @param w Specifies the desired descriptor state.
+   *
+   * @param handler The handler to be called when the wait operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error // Result of operation
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @par Example
+   * @code
+   * void wait_handler(const boost::system::error_code& error)
+   * {
+   *   if (!error)
+   *   {
+   *     // Wait succeeded.
+   *   }
+   * }
+   *
+   * ...
+   *
+   * boost::asio::posix::stream_descriptor descriptor(io_context);
+   * ...
+   * descriptor.async_wait(
+   *     boost::asio::posix::stream_descriptor::wait_read,
+   *     wait_handler);
+   * @endcode
+   */
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(wait_type w, BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WaitHandler.
+    BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
+
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_wait(
+        this->get_implementation(), w, init.completion_handler);
+
+    return init.result.get();
+  }
+
+protected:
+  /// Protected destructor to prevent deletion through this type.
+  /**
+   * This function destroys the descriptor, cancelling any outstanding
+   * asynchronous wait operations associated with the descriptor as if by
+   * calling @c cancel.
+   */
+  ~descriptor()
+  {
+  }
+};
+
+} // namespace posix
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#undef BOOST_ASIO_SVC_T
+
+#endif // defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)
+       //   || defined(GENERATING_DOCUMENTATION)
+
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#endif // BOOST_ASIO_POSIX_DESCRIPTOR_HPP
diff --git a/include/boost/asio/posix/descriptor_base.hpp b/include/boost/asio/posix/descriptor_base.hpp
index e23af43bc8..3e547fe87b 100644
--- a/include/boost/asio/posix/descriptor_base.hpp
+++ b/include/boost/asio/posix/descriptor_base.hpp
@@ -29,33 +29,26 @@ namespace boost {
 namespace asio {
 namespace posix {
 
-/// The descriptor_base class is used as a base for the basic_stream_descriptor
-/// class template so that we have a common place to define the associated
-/// IO control commands.
+/// The descriptor_base class is used as a base for the descriptor class as a
+/// place to define the associated IO control commands.
 class descriptor_base
 {
 public:
-  /// (Deprecated: Use non_blocking().) IO control command to set the blocking
-  /// mode of the descriptor.
+  /// Wait types.
   /**
-   * Implements the FIONBIO IO control command.
-   *
-   * @par Example
-   * @code
-   * boost::asio::posix::stream_descriptor descriptor(io_service); 
-   * ...
-   * boost::asio::descriptor_base::non_blocking_io command(true);
-   * descriptor.io_control(command);
-   * @endcode
-   *
-   * @par Concepts:
-   * IoControlCommand.
+   * For use with descriptor::wait() and descriptor::async_wait().
    */
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined non_blocking_io;
-#else
-  typedef boost::asio::detail::io_control::non_blocking_io non_blocking_io;
-#endif
+  enum wait_type
+  {
+    /// Wait for a descriptor to become ready to read.
+    wait_read,
+
+    /// Wait for a descriptor to become ready to write.
+    wait_write,
+
+    /// Wait for a descriptor to have error conditions pending.
+    wait_error
+  };
 
   /// IO control command to get the amount of data that can be read without
   /// blocking.
@@ -64,7 +57,7 @@ class descriptor_base
    *
    * @par Example
    * @code
-   * boost::asio::posix::stream_descriptor descriptor(io_service); 
+   * boost::asio::posix::stream_descriptor descriptor(io_context); 
    * ...
    * boost::asio::descriptor_base::bytes_readable command(true);
    * descriptor.io_control(command);
diff --git a/include/boost/asio/posix/stream_descriptor.hpp b/include/boost/asio/posix/stream_descriptor.hpp
index d6d1344702..86db187ded 100644
--- a/include/boost/asio/posix/stream_descriptor.hpp
+++ b/include/boost/asio/posix/stream_descriptor.hpp
@@ -16,18 +16,341 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <boost/asio/posix/descriptor.hpp>
 
 #if defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR) \
   || defined(GENERATING_DOCUMENTATION)
 
-#include <boost/asio/posix/basic_stream_descriptor.hpp>
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/posix/basic_stream_descriptor.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 namespace boost {
 namespace asio {
 namespace posix {
 
-/// Typedef for the typical usage of a stream-oriented descriptor.
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+// Typedef for the typical usage of a stream-oriented descriptor.
 typedef basic_stream_descriptor<> stream_descriptor;
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+/// Provides stream-oriented descriptor functionality.
+/**
+ * The posix::stream_descriptor class template provides asynchronous and
+ * blocking stream-oriented descriptor functionality.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ *
+ * @par Concepts:
+ * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream.
+ */
+class stream_descriptor
+  : public descriptor
+{
+public:
+  /// Construct a stream_descriptor without opening it.
+  /**
+   * This constructor creates a stream descriptor without opening it. The
+   * descriptor needs to be opened and then connected or accepted before data
+   * can be sent or received on it.
+   *
+   * @param io_context The io_context object that the stream descriptor will
+   * use to dispatch handlers for any asynchronous operations performed on the
+   * descriptor.
+   */
+  explicit stream_descriptor(boost::asio::io_context& io_context)
+    : descriptor(io_context)
+  {
+  }
+
+  /// Construct a stream_descriptor on an existing native descriptor.
+  /**
+   * This constructor creates a stream descriptor object to hold an existing
+   * native descriptor.
+   *
+   * @param io_context The io_context object that the stream descriptor will
+   * use to dispatch handlers for any asynchronous operations performed on the
+   * descriptor.
+   *
+   * @param native_descriptor The new underlying descriptor implementation.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  stream_descriptor(boost::asio::io_context& io_context,
+      const native_handle_type& native_descriptor)
+    : descriptor(io_context, native_descriptor)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a stream_descriptor from another.
+  /**
+   * This constructor moves a stream descriptor from one object to another.
+   *
+   * @param other The other stream_descriptor object from which the move
+   * will occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c stream_descriptor(io_context&) constructor.
+   */
+  stream_descriptor(stream_descriptor&& other)
+    : descriptor(std::move(other))
+  {
+  }
+
+  /// Move-assign a stream_descriptor from another.
+  /**
+   * This assignment operator moves a stream descriptor from one object to
+   * another.
+   *
+   * @param other The other stream_descriptor object from which the move
+   * will occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c stream_descriptor(io_context&) constructor.
+   */
+  stream_descriptor& operator=(stream_descriptor&& other)
+  {
+    descriptor::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Write some data to the descriptor.
+  /**
+   * This function is used to write data to the stream descriptor. The function
+   * call will block until one or more bytes of the data has been written
+   * successfully, or until an error occurs.
+   *
+   * @param buffers One or more data buffers to be written to the descriptor.
+   *
+   * @returns The number of bytes written.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The write_some operation may not transmit all of the data to the
+   * peer. Consider using the @ref write function if you need to ensure that
+   * all data is written before the blocking operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * descriptor.write_some(boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().write_some(
+        this->get_implementation(), buffers, ec);
+    boost::asio::detail::throw_error(ec, "write_some");
+    return s;
+  }
+
+  /// Write some data to the descriptor.
+  /**
+   * This function is used to write data to the stream descriptor. The function
+   * call will block until one or more bytes of the data has been written
+   * successfully, or until an error occurs.
+   *
+   * @param buffers One or more data buffers to be written to the descriptor.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes written. Returns 0 if an error occurred.
+   *
+   * @note The write_some operation may not transmit all of the data to the
+   * peer. Consider using the @ref write function if you need to ensure that
+   * all data is written before the blocking operation completes.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers,
+      boost::system::error_code& ec)
+  {
+    return this->get_service().write_some(
+        this->get_implementation(), buffers, ec);
+  }
+
+  /// Start an asynchronous write.
+  /**
+   * This function is used to asynchronously write data to the stream
+   * descriptor. The function call always returns immediately.
+   *
+   * @param buffers One or more data buffers to be written to the descriptor.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the write operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes written.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The write operation may not transmit all of the data to the peer.
+   * Consider using the @ref async_write function if you need to ensure that all
+   * data is written before the asynchronous operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * descriptor.async_write_some(boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence, typename WriteHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+      void (boost::system::error_code, std::size_t))
+  async_write_some(const ConstBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WriteHandler.
+    BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
+
+    boost::asio::async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_write_some(
+        this->get_implementation(), buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+
+  /// Read some data from the descriptor.
+  /**
+   * This function is used to read data from the stream descriptor. The function
+   * call will block until one or more bytes of data has been read successfully,
+   * or until an error occurs.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @returns The number of bytes read.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * descriptor.read_some(boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().read_some(
+        this->get_implementation(), buffers, ec);
+    boost::asio::detail::throw_error(ec, "read_some");
+    return s;
+  }
+
+  /// Read some data from the descriptor.
+  /**
+   * This function is used to read data from the stream descriptor. The function
+   * call will block until one or more bytes of data has been read successfully,
+   * or until an error occurs.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes read. Returns 0 if an error occurred.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers,
+      boost::system::error_code& ec)
+  {
+    return this->get_service().read_some(
+        this->get_implementation(), buffers, ec);
+  }
+
+  /// Start an asynchronous read.
+  /**
+   * This function is used to asynchronously read data from the stream
+   * descriptor. The function call always returns immediately.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the read operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes read.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The read operation may not read all of the requested number of bytes.
+   * Consider using the @ref async_read function if you need to ensure that the
+   * requested amount of data is read before the asynchronous operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * descriptor.async_read_some(boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence, typename ReadHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+      void (boost::system::error_code, std::size_t))
+  async_read_some(const MutableBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a ReadHandler.
+    BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
+
+    boost::asio::async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_read_some(
+        this->get_implementation(), buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+};
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 } // namespace posix
 } // namespace asio
diff --git a/include/boost/asio/posix/stream_descriptor_service.hpp b/include/boost/asio/posix/stream_descriptor_service.hpp
index e42580d3f3..0648781505 100644
--- a/include/boost/asio/posix/stream_descriptor_service.hpp
+++ b/include/boost/asio/posix/stream_descriptor_service.hpp
@@ -17,13 +17,15 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR) \
   || defined(GENERATING_DOCUMENTATION)
 
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/reactive_descriptor_service.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -35,7 +37,7 @@ namespace posix {
 /// Default service implementation for a stream descriptor.
 class stream_descriptor_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<stream_descriptor_service>
 #endif
@@ -43,7 +45,7 @@ class stream_descriptor_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
 private:
@@ -58,13 +60,6 @@ class stream_descriptor_service
   typedef service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native descriptor type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native descriptor type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -72,10 +67,10 @@ class stream_descriptor_service
   typedef service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new stream descriptor service for the specified io_service.
-  explicit stream_descriptor_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<stream_descriptor_service>(io_service),
-      service_impl_(io_service)
+  /// Construct a new stream descriptor service for the specified io_context.
+  explicit stream_descriptor_service(boost::asio::io_context& io_context)
+    : boost::asio::detail::service_base<stream_descriptor_service>(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -109,11 +104,12 @@ class stream_descriptor_service
   }
 
   /// Assign an existing native descriptor to a stream descriptor.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const native_handle_type& native_descriptor,
       boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, native_descriptor, ec);
+    service_impl_.assign(impl, native_descriptor, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the descriptor is open.
@@ -123,17 +119,11 @@ class stream_descriptor_service
   }
 
   /// Close a stream descriptor implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
-  }
-
-  /// (Deprecated: Use native_handle().) Get the native descriptor
-  /// implementation.
-  native_type native(implementation_type& impl)
-  {
-    return service_impl_.native_handle(impl);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native descriptor implementation.
@@ -149,18 +139,20 @@ class stream_descriptor_service
   }
 
   /// Cancel all asynchronous operations associated with the descriptor.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the descriptor.
   template <typename IoControlCommand>
-  boost::system::error_code io_control(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID io_control(implementation_type& impl,
       IoControlCommand& command, boost::system::error_code& ec)
   {
-    return service_impl_.io_control(impl, command, ec);
+    service_impl_.io_control(impl, command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the descriptor.
@@ -170,10 +162,11 @@ class stream_descriptor_service
   }
 
   /// Sets the non-blocking mode of the descriptor.
-  boost::system::error_code non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.non_blocking(impl, mode, ec);
+    service_impl_.non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native descriptor implementation.
@@ -183,10 +176,36 @@ class stream_descriptor_service
   }
 
   /// Sets the non-blocking mode of the native descriptor implementation.
-  boost::system::error_code native_non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.native_non_blocking(impl, mode, ec);
+    service_impl_.native_non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the descriptor to become ready to read, ready to write, or to
+  /// have pending error conditions.
+  BOOST_ASIO_SYNC_OP_VOID wait(implementation_type& impl,
+      descriptor_base::wait_type w, boost::system::error_code& ec)
+  {
+    service_impl_.wait(impl, w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the descriptor to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(implementation_type& impl, descriptor_base::wait_type w,
+      BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    service_impl_.async_wait(impl, w, init.completion_handler);
+
+    return init.result.get();
   }
 
   /// Write the given data to the stream.
@@ -205,11 +224,10 @@ class stream_descriptor_service
       const ConstBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    boost::asio::async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_write_some(impl, buffers, init.handler);
+    service_impl_.async_write_some(impl, buffers, init.completion_handler);
 
     return init.result.get();
   }
@@ -230,20 +248,19 @@ class stream_descriptor_service
       const MutableBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    boost::asio::async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_read_some(impl, buffers, init.handler);
+    service_impl_.async_read_some(impl, buffers, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -259,4 +276,6 @@ class stream_descriptor_service
 #endif // defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_POSIX_STREAM_DESCRIPTOR_SERVICE_HPP
diff --git a/include/boost/asio/post.hpp b/include/boost/asio/post.hpp
new file mode 100644
index 0000000000..65e858fd88
--- /dev/null
+++ b/include/boost/asio/post.hpp
@@ -0,0 +1,109 @@
+//
+// post.hpp
+// ~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_POST_HPP
+#define BOOST_ASIO_POST_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/execution_context.hpp>
+#include <boost/asio/is_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// Submits a completion token or function object for execution.
+/**
+ * This function submits an object for execution using the object's associated
+ * executor. The function object is queued for execution, and is never called
+ * from the current thread prior to returning from <tt>post()</tt>.
+ *
+ * This function has the following effects:
+ *
+ * @li Constructs a function object handler of type @c Handler, initialized
+ * with <tt>handler(forward<CompletionToken>(token))</tt>.
+ *
+ * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
+ * initializing the object as <tt>result(handler)</tt>.
+ *
+ * @li Obtains the handler's associated executor object @c ex by performing
+ * <tt>get_associated_executor(handler)</tt>.
+ *
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * <tt>get_associated_allocator(handler)</tt>.
+ *
+ * @li Performs <tt>ex.post(std::move(handler), alloc)</tt>.
+ *
+ * @li Returns <tt>result.get()</tt>.
+ */
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) post(
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token);
+
+/// Submits a completion token or function object for execution.
+/**
+ * This function submits an object for execution using the specified executor.
+ * The function object is queued for execution, and is never called from the
+ * current thread prior to returning from <tt>post()</tt>.
+ *
+ * This function has the following effects:
+ *
+ * @li Constructs a function object handler of type @c Handler, initialized
+ * with <tt>handler(forward<CompletionToken>(token))</tt>.
+ *
+ * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
+ * initializing the object as <tt>result(handler)</tt>.
+ *
+ * @li Obtains the handler's associated executor object @c ex1 by performing
+ * <tt>get_associated_executor(handler)</tt>.
+ *
+ * @li Creates a work object @c w by performing <tt>make_work(ex1)</tt>.
+ *
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * <tt>get_associated_allocator(handler)</tt>.
+ *
+ * @li Constructs a function object @c f with a function call operator that
+ * performs <tt>ex1.dispatch(std::move(handler), alloc)</tt> followed by
+ * <tt>w.reset()</tt>.
+ *
+ * @li Performs <tt>Executor(ex).post(std::move(f), alloc)</tt>.
+ *
+ * @li Returns <tt>result.get()</tt>.
+ */
+template <typename Executor, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) post(
+    const Executor& ex, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_executor<Executor>::value>::type* = 0);
+
+/// Submits a completion token or function object for execution.
+/**
+ * @returns <tt>post(ctx.get_executor(), forward<CompletionToken>(token))</tt>.
+ */
+template <typename ExecutionContext, typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) post(
+    ExecutionContext& ctx, BOOST_ASIO_MOVE_ARG(CompletionToken) token,
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type* = 0);
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/post.hpp>
+
+#endif // BOOST_ASIO_POST_HPP
diff --git a/include/boost/asio/raw_socket_service.hpp b/include/boost/asio/raw_socket_service.hpp
index 06880d5abb..9a777013e2 100644
--- a/include/boost/asio/raw_socket_service.hpp
+++ b/include/boost/asio/raw_socket_service.hpp
@@ -16,11 +16,14 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/null_socket_service.hpp>
@@ -39,7 +42,7 @@ namespace asio {
 template <typename Protocol>
 class raw_socket_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<raw_socket_service<Protocol> >
 #endif
@@ -47,7 +50,7 @@ class raw_socket_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The protocol type.
@@ -74,13 +77,6 @@ class raw_socket_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native socket type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef typename service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native socket type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -88,11 +84,11 @@ class raw_socket_service
   typedef typename service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new raw socket service for the specified io_service.
-  explicit raw_socket_service(boost::asio::io_service& io_service)
+  /// Construct a new raw socket service for the specified io_context.
+  explicit raw_socket_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        raw_socket_service<Protocol> >(io_service),
-      service_impl_(io_service)
+        raw_socket_service<Protocol> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -143,22 +139,23 @@ class raw_socket_service
   }
 
   // Open a new raw socket implementation.
-  boost::system::error_code open(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID open(implementation_type& impl,
       const protocol_type& protocol, boost::system::error_code& ec)
   {
     if (protocol.type() == BOOST_ASIO_OS_DEF(SOCK_RAW))
       service_impl_.open(impl, protocol, ec);
     else
       ec = boost::asio::error::invalid_argument;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native socket to a raw socket.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const protocol_type& protocol, const native_handle_type& native_socket,
       boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, protocol, native_socket, ec);
+    service_impl_.assign(impl, protocol, native_socket, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is open.
@@ -168,16 +165,18 @@ class raw_socket_service
   }
 
   /// Close a raw socket implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  /// (Deprecated: Use native_handle().) Get the native socket implementation.
-  native_type native(implementation_type& impl)
+  /// Release ownership of the underlying socket.
+  native_handle_type release(implementation_type& impl,
+      boost::system::error_code& ec)
   {
-    return service_impl_.native_handle(impl);
+    return service_impl_.release(impl, ec);
   }
 
   /// Get the native socket implementation.
@@ -187,10 +186,11 @@ class raw_socket_service
   }
 
   /// Cancel all asynchronous operations associated with the socket.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is at the out-of-band data mark.
@@ -208,17 +208,19 @@ class raw_socket_service
   }
 
   // Bind the raw socket to the specified local endpoint.
-  boost::system::error_code bind(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID bind(implementation_type& impl,
       const endpoint_type& endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.bind(impl, endpoint, ec);
+    service_impl_.bind(impl, endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Connect the raw socket to the specified endpoint.
-  boost::system::error_code connect(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID connect(implementation_type& impl,
       const endpoint_type& peer_endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.connect(impl, peer_endpoint, ec);
+    service_impl_.connect(impl, peer_endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous connect.
@@ -229,37 +231,39 @@ class raw_socket_service
       const endpoint_type& peer_endpoint,
       BOOST_ASIO_MOVE_ARG(ConnectHandler) handler)
   {
-    detail::async_result_init<
-      ConnectHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(ConnectHandler)(handler));
+    async_completion<ConnectHandler,
+      void (boost::system::error_code)> init(handler);
 
-    service_impl_.async_connect(impl, peer_endpoint, init.handler);
+    service_impl_.async_connect(impl, peer_endpoint, init.completion_handler);
 
     return init.result.get();
   }
 
   /// Set a socket option.
   template <typename SettableSocketOption>
-  boost::system::error_code set_option(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID set_option(implementation_type& impl,
       const SettableSocketOption& option, boost::system::error_code& ec)
   {
-    return service_impl_.set_option(impl, option, ec);
+    service_impl_.set_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get a socket option.
   template <typename GettableSocketOption>
-  boost::system::error_code get_option(const implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID get_option(const implementation_type& impl,
       GettableSocketOption& option, boost::system::error_code& ec) const
   {
-    return service_impl_.get_option(impl, option, ec);
+    service_impl_.get_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the socket.
   template <typename IoControlCommand>
-  boost::system::error_code io_control(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID io_control(implementation_type& impl,
       IoControlCommand& command, boost::system::error_code& ec)
   {
-    return service_impl_.io_control(impl, command, ec);
+    service_impl_.io_control(impl, command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the socket.
@@ -269,10 +273,11 @@ class raw_socket_service
   }
 
   /// Sets the non-blocking mode of the socket.
-  boost::system::error_code non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.non_blocking(impl, mode, ec);
+    service_impl_.non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native socket implementation.
@@ -282,10 +287,11 @@ class raw_socket_service
   }
 
   /// Sets the non-blocking mode of the native socket implementation.
-  boost::system::error_code native_non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.native_non_blocking(impl, mode, ec);
+    service_impl_.native_non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the local endpoint.
@@ -303,10 +309,36 @@ class raw_socket_service
   }
 
   /// Disable sends or receives on the socket.
-  boost::system::error_code shutdown(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID shutdown(implementation_type& impl,
       socket_base::shutdown_type what, boost::system::error_code& ec)
   {
-    return service_impl_.shutdown(impl, what, ec);
+    service_impl_.shutdown(impl, what, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the socket to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  BOOST_ASIO_SYNC_OP_VOID wait(implementation_type& impl,
+      socket_base::wait_type w, boost::system::error_code& ec)
+  {
+    service_impl_.wait(impl, w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the socket to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(implementation_type& impl, socket_base::wait_type w,
+      BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    service_impl_.async_wait(impl, w, init.completion_handler);
+
+    return init.result.get();
   }
 
   /// Send the given data to the peer.
@@ -326,11 +358,10 @@ class raw_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_send(impl, buffers, flags, init.handler);
+    service_impl_.async_send(impl, buffers, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -353,12 +384,11 @@ class raw_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     service_impl_.async_send_to(impl, buffers,
-        destination, flags, init.handler);
+        destination, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -381,11 +411,10 @@ class raw_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_receive(impl, buffers, flags, init.handler);
+    service_impl_.async_receive(impl, buffers, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -409,21 +438,20 @@ class raw_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     service_impl_.async_receive_from(impl, buffers,
-        sender_endpoint, flags, init.handler);
+        sender_endpoint, flags, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -435,4 +463,6 @@ class raw_socket_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_RAW_SOCKET_SERVICE_HPP
diff --git a/include/boost/asio/read.hpp b/include/boost/asio/read.hpp
index 0db29b7831..d03ed5a73d 100644
--- a/include/boost/asio/read.hpp
+++ b/include/boost/asio/read.hpp
@@ -18,9 +18,13 @@
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
-#include <boost/asio/basic_streambuf_fwd.hpp>
+#include <boost/asio/buffer.hpp>
 #include <boost/asio/error.hpp>
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+# include <boost/asio/basic_streambuf_fwd.hpp>
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -71,7 +75,10 @@ namespace asio {
  *     boost::asio::transfer_all()); @endcode
  */
 template <typename SyncReadStream, typename MutableBufferSequence>
-std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers);
+std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type* = 0);
 
 /// Attempt to read a certain amount of data from a stream before returning.
 /**
@@ -111,7 +118,10 @@ std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers);
  */
 template <typename SyncReadStream, typename MutableBufferSequence>
 std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
-    boost::system::error_code& ec);
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type* = 0);
 
 /// Attempt to read a certain amount of data from a stream before returning.
 /**
@@ -162,7 +172,10 @@ std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
 template <typename SyncReadStream, typename MutableBufferSequence,
   typename CompletionCondition>
 std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
-    CompletionCondition completion_condition);
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type* = 0);
 
 /// Attempt to read a certain amount of data from a stream before returning.
 /**
@@ -206,8 +219,171 @@ std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
 template <typename SyncReadStream, typename MutableBufferSequence,
     typename CompletionCondition>
 std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
-    CompletionCondition completion_condition, boost::system::error_code& ec);
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type* = 0);
+
+/// Attempt to read a certain amount of data from a stream before returning.
+/**
+ * This function is used to read a certain number of bytes of data from a
+ * stream. The call will block until one of the following conditions is true:
+ *
+ * @li The specified dynamic buffer sequence is full (that is, it has reached
+ * maximum size).
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ *
+ * @returns The number of bytes transferred.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note This overload is equivalent to calling:
+ * @code boost::asio::read(
+ *     s, buffers,
+ *     boost::asio::transfer_all()); @endcode
+ */
+template <typename SyncReadStream, typename DynamicBuffer>
+std::size_t read(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+/// Attempt to read a certain amount of data from a stream before returning.
+/**
+ * This function is used to read a certain number of bytes of data from a
+ * stream. The call will block until one of the following conditions is true:
+ *
+ * @li The supplied buffer is full (that is, it has reached maximum size).
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes transferred.
+ *
+ * @note This overload is equivalent to calling:
+ * @code boost::asio::read(
+ *     s, buffers,
+ *     boost::asio::transfer_all(), ec); @endcode
+ */
+template <typename SyncReadStream, typename DynamicBuffer>
+std::size_t read(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+/// Attempt to read a certain amount of data from a stream before returning.
+/**
+ * This function is used to read a certain number of bytes of data from a
+ * stream. The call will block until one of the following conditions is true:
+ *
+ * @li The specified dynamic buffer sequence is full (that is, it has reached
+ * maximum size).
+ *
+ * @li The completion_condition function object returns 0.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ *
+ * @param completion_condition The function object to be called to determine
+ * whether the read operation is complete. The signature of the function object
+ * must be:
+ * @code std::size_t completion_condition(
+ *   // Result of latest read_some operation.
+ *   const boost::system::error_code& error,
+ *
+ *   // Number of bytes transferred so far.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * A return value of 0 indicates that the read operation is complete. A non-zero
+ * return value indicates the maximum number of bytes to be read on the next
+ * call to the stream's read_some function.
+ *
+ * @returns The number of bytes transferred.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ */
+template <typename SyncReadStream, typename DynamicBuffer,
+    typename CompletionCondition>
+std::size_t read(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
 
+/// Attempt to read a certain amount of data from a stream before returning.
+/**
+ * This function is used to read a certain number of bytes of data from a
+ * stream. The call will block until one of the following conditions is true:
+ *
+ * @li The specified dynamic buffer sequence is full (that is, it has reached
+ * maximum size).
+ *
+ * @li The completion_condition function object returns 0.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ *
+ * @param completion_condition The function object to be called to determine
+ * whether the read operation is complete. The signature of the function object
+ * must be:
+ * @code std::size_t completion_condition(
+ *   // Result of latest read_some operation.
+ *   const boost::system::error_code& error,
+ *
+ *   // Number of bytes transferred so far.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * A return value of 0 indicates that the read operation is complete. A non-zero
+ * return value indicates the maximum number of bytes to be read on the next
+ * call to the stream's read_some function.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes read. If an error occurs, returns the total
+ * number of bytes successfully transferred prior to the error.
+ */
+template <typename SyncReadStream, typename DynamicBuffer,
+    typename CompletionCondition>
+std::size_t read(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Attempt to read a certain amount of data from a stream before returning.
@@ -351,6 +527,7 @@ std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b,
     CompletionCondition completion_condition, boost::system::error_code& ec);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 /**
@@ -404,7 +581,7 @@ std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To read into a single data buffer use the @ref buffer function as follows:
@@ -426,7 +603,10 @@ template <typename AsyncReadStream, typename MutableBufferSequence,
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
-    BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type* = 0);
 
 /// Start an asynchronous operation to read a certain amount of data from a
 /// stream.
@@ -479,7 +659,7 @@ async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To read into a single data buffer use the @ref buffer function as follows:
@@ -497,8 +677,143 @@ BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
     CompletionCondition completion_condition,
-    BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_mutable_buffer_sequence<MutableBufferSequence>::value
+    >::type* = 0);
+
+/// Start an asynchronous operation to read a certain amount of data from a
+/// stream.
+/**
+ * This function is used to asynchronously read a certain number of bytes of
+ * data from a stream. The function call always returns immediately. The
+ * asynchronous operation will continue until one of the following conditions is
+ * true:
+ *
+ * @li The specified dynamic buffer sequence is full (that is, it has reached
+ * maximum size).
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * async_read_some function, and is known as a <em>composed operation</em>. The
+ * program must ensure that the stream performs no other read operations (such
+ * as async_read, the stream's async_read_some function, or any other composed
+ * operations that perform reads) until this operation completes.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the AsyncReadStream concept.
+ *
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called.
+ *
+ * @param handler The handler to be called when the read operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   const boost::system::error_code& error, // Result of operation.
+ *
+ *   std::size_t bytes_transferred           // Number of bytes copied into the
+ *                                           // buffers. If an error occurred,
+ *                                           // this will be the  number of
+ *                                           // bytes successfully transferred
+ *                                           // prior to the error.
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
+ *
+ * @note This overload is equivalent to calling:
+ * @code boost::asio::async_read(
+ *     s, buffers,
+ *     boost::asio::transfer_all(),
+ *     handler); @endcode
+ */
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read(AsyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+/// Start an asynchronous operation to read a certain amount of data from a
+/// stream.
+/**
+ * This function is used to asynchronously read a certain number of bytes of
+ * data from a stream. The function call always returns immediately. The
+ * asynchronous operation will continue until one of the following conditions is
+ * true:
+ *
+ * @li The specified dynamic buffer sequence is full (that is, it has reached
+ * maximum size).
+ *
+ * @li The completion_condition function object returns 0.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * async_read_some function, and is known as a <em>composed operation</em>. The
+ * program must ensure that the stream performs no other read operations (such
+ * as async_read, the stream's async_read_some function, or any other composed
+ * operations that perform reads) until this operation completes.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the AsyncReadStream concept.
+ *
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called.
+ *
+ * @param completion_condition The function object to be called to determine
+ * whether the read operation is complete. The signature of the function object
+ * must be:
+ * @code std::size_t completion_condition(
+ *   // Result of latest async_read_some operation.
+ *   const boost::system::error_code& error,
+ *
+ *   // Number of bytes transferred so far.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * A return value of 0 indicates that the read operation is complete. A non-zero
+ * return value indicates the maximum number of bytes to be read on the next
+ * call to the stream's async_read_some function.
+ *
+ * @param handler The handler to be called when the read operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   const boost::system::error_code& error, // Result of operation.
+ *
+ *   std::size_t bytes_transferred           // Number of bytes copied into the
+ *                                           // buffers. If an error occurred,
+ *                                           // this will be the  number of
+ *                                           // bytes successfully transferred
+ *                                           // prior to the error.
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
+ */
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename CompletionCondition, typename ReadHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read(AsyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Start an asynchronous operation to read a certain amount of data from a
@@ -541,7 +856,7 @@ async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @note This overload is equivalent to calling:
  * @code boost::asio::async_read(
@@ -609,7 +924,7 @@ async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  */
 template <typename AsyncReadStream, typename Allocator,
     typename CompletionCondition, typename ReadHandler>
@@ -620,6 +935,7 @@ async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b,
     BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 
diff --git a/include/boost/asio/read_at.hpp b/include/boost/asio/read_at.hpp
index 03f6c155c1..fc10c8115e 100644
--- a/include/boost/asio/read_at.hpp
+++ b/include/boost/asio/read_at.hpp
@@ -18,10 +18,13 @@
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
-#include <boost/asio/basic_streambuf_fwd.hpp>
 #include <boost/asio/detail/cstdint.hpp>
 #include <boost/asio/error.hpp>
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+# include <boost/asio/basic_streambuf_fwd.hpp>
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -230,6 +233,7 @@ std::size_t read_at(SyncRandomAccessReadDevice& d,
     uint64_t offset, const MutableBufferSequence& buffers,
     CompletionCondition completion_condition, boost::system::error_code& ec);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Attempt to read a certain amount of data at the specified offset before
@@ -385,6 +389,7 @@ std::size_t read_at(SyncRandomAccessReadDevice& d,
     CompletionCondition completion_condition, boost::system::error_code& ec);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 /**
@@ -437,7 +442,7 @@ std::size_t read_at(SyncRandomAccessReadDevice& d,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To read into a single data buffer use the @ref buffer function as follows:
@@ -515,7 +520,7 @@ async_read_at(AsyncRandomAccessReadDevice& d, uint64_t offset,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To read into a single data buffer use the @ref buffer function as follows:
@@ -536,6 +541,7 @@ async_read_at(AsyncRandomAccessReadDevice& d,
     CompletionCondition completion_condition,
     BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Start an asynchronous operation to read a certain amount of data at the
@@ -575,7 +581,7 @@ async_read_at(AsyncRandomAccessReadDevice& d,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @note This overload is equivalent to calling:
  * @code boost::asio::async_read_at(
@@ -641,7 +647,7 @@ async_read_at(AsyncRandomAccessReadDevice& d, uint64_t offset,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  */
 template <typename AsyncRandomAccessReadDevice, typename Allocator,
     typename CompletionCondition, typename ReadHandler>
@@ -653,6 +659,7 @@ async_read_at(AsyncRandomAccessReadDevice& d,
     BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 
diff --git a/include/boost/asio/read_until.hpp b/include/boost/asio/read_until.hpp
index 3ed288fc2c..ee4e68b84f 100644
--- a/include/boost/asio/read_until.hpp
+++ b/include/boost/asio/read_until.hpp
@@ -16,17 +16,18 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-
-#if !defined(BOOST_ASIO_NO_IOSTREAM)
-
 #include <cstddef>
 #include <string>
 #include <boost/asio/async_result.hpp>
-#include <boost/asio/basic_streambuf.hpp>
 #include <boost/asio/detail/regex_fwd.hpp>
+#include <boost/asio/detail/string_view.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+# include <boost/asio/basic_streambuf_fwd.hpp>
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -67,289 +68,1221 @@ struct is_match_condition
 /**
  * @defgroup read_until boost::asio::read_until
  *
- * @brief Read data into a streambuf until it contains a delimiter, matches a
- * regular expression, or a function object indicates a match.
+ * @brief Read data into a dynamic buffer sequence, or into a streambuf, until
+ * it contains a delimiter, matches a regular expression, or a function object
+ * indicates a match.
  */
 /*@{*/
 
-/// Read data into a streambuf until it contains a specified delimiter.
+/// Read data into a dynamic buffer sequence until it contains a specified
+/// delimiter.
 /**
- * This function is used to read data into the specified streambuf until the
- * streambuf's get area contains the specified delimiter. The call will block
- * until one of the following conditions is true:
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until the dynamic buffer sequence's get area contains the specified
+ * delimiter. The call will block until one of the following conditions is
+ * true:
  *
- * @li The get area of the streambuf contains the specified delimiter.
+ * @li The get area of the dynamic buffer sequence contains the specified
+ * delimiter.
  *
  * @li An error occurred.
  *
  * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the streambuf's get area already contains the
- * delimiter, the function returns immediately.
+ * read_some function. If the dynamic buffer sequence's get area already
+ * contains the delimiter, the function returns immediately.
  *
  * @param s The stream from which the data is to be read. The type must support
  * the SyncReadStream concept.
  *
- * @param b A streambuf object into which the data will be read.
+ * @param buffers The dynamic buffer sequence into which the data will be read.
  *
  * @param delim The delimiter character.
  *
- * @returns The number of bytes in the streambuf's get area up to and including
- * the delimiter.
+ * @returns The number of bytes in the dynamic buffer sequence's get area up to
+ * and including the delimiter.
  *
  * @throws boost::system::system_error Thrown on failure.
  *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond the delimiter. An application will typically leave
- * that data in the streambuf for a subsequent read_until operation to examine.
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond the delimiter. An application will
+ * typically leave that data in the dynamic buffer sequence for a subsequent
+ * read_until operation to examine.
  *
  * @par Example
- * To read data into a streambuf until a newline is encountered:
- * @code boost::asio::streambuf b;
- * boost::asio::read_until(s, b, '\n');
- * std::istream is(&b);
- * std::string line;
- * std::getline(is, line); @endcode
- * After the @c read_until operation completes successfully, the buffer @c b
+ * To read data into a @c std::string until a newline is encountered:
+ * @code std::string data;
+ * std::string n = boost::asio::read_until(s,
+ *     boost::asio::dynamic_buffer(data), '\n');
+ * std::string line = data.substr(0, n);
+ * data.erase(0, n); @endcode
+ * After the @c read_until operation completes successfully, the string @c data
  * contains the delimiter:
  * @code { 'a', 'b', ..., 'c', '\n', 'd', 'e', ... } @endcode
- * The call to @c std::getline then extracts the data up to and including the
+ * The call to @c substr then extracts the data up to and including the
  * delimiter, so that the string @c line contains:
  * @code { 'a', 'b', ..., 'c', '\n' } @endcode
- * The remaining data is left in the buffer @c b as follows:
+ * After the call to @c erase, the remaining data is left in the buffer @c b as
+ * follows:
  * @code { 'd', 'e', ... } @endcode
  * This data may be the start of a new line, to be extracted by a subsequent
  * @c read_until operation.
  */
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, char delim);
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers, char delim);
 
-/// Read data into a streambuf until it contains a specified delimiter.
+/// Read data into a dynamic buffer sequence until it contains a specified
+/// delimiter.
 /**
- * This function is used to read data into the specified streambuf until the
- * streambuf's get area contains the specified delimiter. The call will block
- * until one of the following conditions is true:
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until the dynamic buffer sequence's get area contains the specified
+ * delimiter. The call will block until one of the following conditions is
+ * true:
  *
- * @li The get area of the streambuf contains the specified delimiter.
+ * @li The get area of the dynamic buffer sequence contains the specified
+ * delimiter.
  *
  * @li An error occurred.
  *
  * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the streambuf's get area already contains the
- * delimiter, the function returns immediately.
+ * read_some function. If the dynamic buffer sequence's get area already
+ * contains the delimiter, the function returns immediately.
  *
  * @param s The stream from which the data is to be read. The type must support
  * the SyncReadStream concept.
  *
- * @param b A streambuf object into which the data will be read.
+ * @param buffers The dynamic buffer sequence into which the data will be read.
  *
  * @param delim The delimiter character.
  *
  * @param ec Set to indicate what error occurred, if any.
  *
- * @returns The number of bytes in the streambuf's get area up to and including
- * the delimiter. Returns 0 if an error occurred.
+ * @returns The number of bytes in the dynamic buffer sequence's get area up to
+ * and including the delimiter. Returns 0 if an error occurred.
  *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond the delimiter. An application will typically leave
- * that data in the streambuf for a subsequent read_until operation to examine.
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond the delimiter. An application will
+ * typically leave that data in the dynamic buffer sequence for a subsequent
+ * read_until operation to examine.
  */
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, char delim,
-    boost::system::error_code& ec);
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    char delim, boost::system::error_code& ec);
 
-/// Read data into a streambuf until it contains a specified delimiter.
+/// Read data into a dynamic buffer sequence until it contains a specified
+/// delimiter.
 /**
- * This function is used to read data into the specified streambuf until the
- * streambuf's get area contains the specified delimiter. The call will block
- * until one of the following conditions is true:
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until the dynamic buffer sequence's get area contains the specified
+ * delimiter. The call will block until one of the following conditions is
+ * true:
  *
- * @li The get area of the streambuf contains the specified delimiter.
+ * @li The get area of the dynamic buffer sequence contains the specified
+ * delimiter.
  *
  * @li An error occurred.
  *
  * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the streambuf's get area already contains the
- * delimiter, the function returns immediately.
+ * read_some function. If the dynamic buffer sequence's get area already
+ * contains the delimiter, the function returns immediately.
  *
  * @param s The stream from which the data is to be read. The type must support
  * the SyncReadStream concept.
  *
- * @param b A streambuf object into which the data will be read.
+ * @param buffers The dynamic buffer sequence into which the data will be read.
  *
  * @param delim The delimiter string.
  *
- * @returns The number of bytes in the streambuf's get area up to and including
- * the delimiter.
- *
- * @throws boost::system::system_error Thrown on failure.
+ * @returns The number of bytes in the dynamic buffer sequence's get area up to
+ * and including the delimiter.
  *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond the delimiter. An application will typically leave
- * that data in the streambuf for a subsequent read_until operation to examine.
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond the delimiter. An application will
+ * typically leave that data in the dynamic buffer sequence for a subsequent
+ * read_until operation to examine.
  *
  * @par Example
- * To read data into a streambuf until a newline is encountered:
- * @code boost::asio::streambuf b;
- * boost::asio::read_until(s, b, "\r\n");
- * std::istream is(&b);
- * std::string line;
- * std::getline(is, line); @endcode
- * After the @c read_until operation completes successfully, the buffer @c b
+ * To read data into a @c std::string until a CR-LF sequence is encountered:
+ * @code std::string data;
+ * std::string n = boost::asio::read_until(s,
+ *     boost::asio::dynamic_buffer(data), "\r\n");
+ * std::string line = data.substr(0, n);
+ * data.erase(0, n); @endcode
+ * After the @c read_until operation completes successfully, the string @c data
  * contains the delimiter:
  * @code { 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } @endcode
- * The call to @c std::getline then extracts the data up to and including the
+ * The call to @c substr then extracts the data up to and including the
  * delimiter, so that the string @c line contains:
  * @code { 'a', 'b', ..., 'c', '\r', '\n' } @endcode
- * The remaining data is left in the buffer @c b as follows:
+ * After the call to @c erase, the remaining data is left in the buffer @c b as
+ * follows:
  * @code { 'd', 'e', ... } @endcode
  * This data may be the start of a new line, to be extracted by a subsequent
  * @c read_until operation.
  */
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const std::string& delim);
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_STRING_VIEW_PARAM delim);
 
-/// Read data into a streambuf until it contains a specified delimiter.
+/// Read data into a dynamic buffer sequence until it contains a specified
+/// delimiter.
 /**
- * This function is used to read data into the specified streambuf until the
- * streambuf's get area contains the specified delimiter. The call will block
- * until one of the following conditions is true:
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until the dynamic buffer sequence's get area contains the specified
+ * delimiter. The call will block until one of the following conditions is
+ * true:
  *
- * @li The get area of the streambuf contains the specified delimiter.
+ * @li The get area of the dynamic buffer sequence contains the specified
+ * delimiter.
  *
  * @li An error occurred.
  *
  * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the streambuf's get area already contains the
- * delimiter, the function returns immediately.
+ * read_some function. If the dynamic buffer sequence's get area already
+ * contains the delimiter, the function returns immediately.
  *
  * @param s The stream from which the data is to be read. The type must support
  * the SyncReadStream concept.
  *
- * @param b A streambuf object into which the data will be read.
+ * @param buffers The dynamic buffer sequence into which the data will be read.
  *
  * @param delim The delimiter string.
  *
  * @param ec Set to indicate what error occurred, if any.
  *
- * @returns The number of bytes in the streambuf's get area up to and including
- * the delimiter. Returns 0 if an error occurred.
+ * @returns The number of bytes in the dynamic buffer sequence's get area up to
+ * and including the delimiter. Returns 0 if an error occurred.
  *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond the delimiter. An application will typically leave
- * that data in the streambuf for a subsequent read_until operation to examine.
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond the delimiter. An application will
+ * typically leave that data in the dynamic buffer sequence for a subsequent
+ * read_until operation to examine.
  */
-template <typename SyncReadStream, typename Allocator>
+template <typename SyncReadStream, typename DynamicBuffer>
 std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const std::string& delim,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_STRING_VIEW_PARAM delim,
     boost::system::error_code& ec);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if defined(BOOST_ASIO_HAS_BOOST_REGEX) \
   || defined(GENERATING_DOCUMENTATION)
 
-/// Read data into a streambuf until some part of the data it contains matches
-/// a regular expression.
+/// Read data into a dynamic buffer sequence until some part of the data it
+/// contains matches a regular expression.
+/**
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until the dynamic buffer sequence's get area contains some data
+ * that matches a regular expression. The call will block until one of the
+ * following conditions is true:
+ *
+ * @li A substring of the dynamic buffer sequence's get area matches the
+ * regular expression.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the dynamic buffer sequence's get area already
+ * contains data that matches the regular expression, the function returns
+ * immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers A dynamic buffer sequence into which the data will be read.
+ *
+ * @param expr The regular expression.
+ *
+ * @returns The number of bytes in the dynamic buffer sequence's get area up to
+ * and including the substring that matches the regular expression.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond that which matched the regular
+ * expression. An application will typically leave that data in the dynamic
+ * buffer sequence for a subsequent read_until operation to examine.
+ *
+ * @par Example
+ * To read data into a @c std::string until a CR-LF sequence is encountered:
+ * @code std::string data;
+ * std::string n = boost::asio::read_until(s,
+ *     boost::asio::dynamic_buffer(data), boost::regex("\r\n"));
+ * std::string line = data.substr(0, n);
+ * data.erase(0, n); @endcode
+ * After the @c read_until operation completes successfully, the string @c data
+ * contains the delimiter:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } @endcode
+ * The call to @c substr then extracts the data up to and including the
+ * delimiter, so that the string @c line contains:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n' } @endcode
+ * After the call to @c erase, the remaining data is left in the buffer @c b as
+ * follows:
+ * @code { 'd', 'e', ... } @endcode
+ * This data may be the start of a new line, to be extracted by a subsequent
+ * @c read_until operation.
+ */
+template <typename SyncReadStream, typename DynamicBuffer>
+std::size_t read_until(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    const boost::regex& expr);
+
+/// Read data into a dynamic buffer sequence until some part of the data it
+/// contains matches a regular expression.
+/**
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until the dynamic buffer sequence's get area contains some data
+ * that matches a regular expression. The call will block until one of the
+ * following conditions is true:
+ *
+ * @li A substring of the dynamic buffer sequence's get area matches the
+ * regular expression.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the dynamic buffer sequence's get area already
+ * contains data that matches the regular expression, the function returns
+ * immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers A dynamic buffer sequence into which the data will be read.
+ *
+ * @param expr The regular expression.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes in the dynamic buffer sequence's get area up to
+ * and including the substring that matches the regular expression. Returns 0
+ * if an error occurred.
+ *
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond that which matched the regular
+ * expression. An application will typically leave that data in the dynamic
+ * buffer sequence for a subsequent read_until operation to examine.
+ */
+template <typename SyncReadStream, typename DynamicBuffer>
+std::size_t read_until(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    const boost::regex& expr, boost::system::error_code& ec);
+
+#endif // defined(BOOST_ASIO_HAS_BOOST_REGEX)
+       // || defined(GENERATING_DOCUMENTATION)
+
+/// Read data into a dynamic buffer sequence until a function object indicates a
+/// match.
+
+/**
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until a user-defined match condition function object, when applied
+ * to the data contained in the dynamic buffer sequence, indicates a successful
+ * match. The call will block until one of the following conditions is true:
+ *
+ * @li The match condition function object returns a std::pair where the second
+ * element evaluates to true.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the match condition function object already indicates
+ * a match, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers A dynamic buffer sequence into which the data will be read.
+ *
+ * @param match_condition The function object to be called to determine whether
+ * a match exists. The signature of the function object must be:
+ * @code pair<iterator, bool> match_condition(iterator begin, iterator end);
+ * @endcode
+ * where @c iterator represents the type:
+ * @code buffers_iterator<typename DynamicBuffer::const_buffers_type>
+ * @endcode
+ * The iterator parameters @c begin and @c end define the range of bytes to be
+ * scanned to determine whether there is a match. The @c first member of the
+ * return value is an iterator marking one-past-the-end of the bytes that have
+ * been consumed by the match function. This iterator is used to calculate the
+ * @c begin parameter for any subsequent invocation of the match condition. The
+ * @c second member of the return value is true if a match has been found, false
+ * otherwise.
+ *
+ * @returns The number of bytes in the dynamic_buffer's get area that
+ * have been fully consumed by the match function.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond that which matched the function object.
+ * An application will typically leave that data in the dynamic buffer sequence
+ * for a subsequent read_until operation to examine.
+
+ * @note The default implementation of the @c is_match_condition type trait
+ * evaluates to true for function pointers and function objects with a
+ * @c result_type typedef. It must be specialised for other user-defined
+ * function objects.
+ *
+ * @par Examples
+ * To read data into a dynamic buffer sequence until whitespace is encountered:
+ * @code typedef boost::asio::buffers_iterator<
+ *     boost::asio::const_buffers_1> iterator;
+ *
+ * std::pair<iterator, bool>
+ * match_whitespace(iterator begin, iterator end)
+ * {
+ *   iterator i = begin;
+ *   while (i != end)
+ *     if (std::isspace(*i++))
+ *       return std::make_pair(i, true);
+ *   return std::make_pair(i, false);
+ * }
+ * ...
+ * std::string data;
+ * boost::asio::read_until(s, data, match_whitespace);
+ * @endcode
+ *
+ * To read data into a @c std::string until a matching character is found:
+ * @code class match_char
+ * {
+ * public:
+ *   explicit match_char(char c) : c_(c) {}
+ *
+ *   template <typename Iterator>
+ *   std::pair<Iterator, bool> operator()(
+ *       Iterator begin, Iterator end) const
+ *   {
+ *     Iterator i = begin;
+ *     while (i != end)
+ *       if (c_ == *i++)
+ *         return std::make_pair(i, true);
+ *     return std::make_pair(i, false);
+ *   }
+ *
+ * private:
+ *   char c_;
+ * };
+ *
+ * namespace asio {
+ *   template <> struct is_match_condition<match_char>
+ *     : public boost::true_type {};
+ * } // namespace asio
+ * ...
+ * std::string data;
+ * boost::asio::read_until(s, data, match_char('a'));
+ * @endcode
+ */
+template <typename SyncReadStream,
+    typename DynamicBuffer, typename MatchCondition>
+std::size_t read_until(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    MatchCondition match_condition,
+    typename enable_if<is_match_condition<MatchCondition>::value>::type* = 0);
+
+/// Read data into a dynamic buffer sequence until a function object indicates a
+/// match.
+/**
+ * This function is used to read data into the specified dynamic buffer
+ * sequence until a user-defined match condition function object, when applied
+ * to the data contained in the dynamic buffer sequence, indicates a successful
+ * match. The call will block until one of the following conditions is true:
+ *
+ * @li The match condition function object returns a std::pair where the second
+ * element evaluates to true.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the match condition function object already indicates
+ * a match, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param buffers A dynamic buffer sequence into which the data will be read.
+ *
+ * @param match_condition The function object to be called to determine whether
+ * a match exists. The signature of the function object must be:
+ * @code pair<iterator, bool> match_condition(iterator begin, iterator end);
+ * @endcode
+ * where @c iterator represents the type:
+ * @code buffers_iterator<DynamicBuffer::const_buffers_type>
+ * @endcode
+ * The iterator parameters @c begin and @c end define the range of bytes to be
+ * scanned to determine whether there is a match. The @c first member of the
+ * return value is an iterator marking one-past-the-end of the bytes that have
+ * been consumed by the match function. This iterator is used to calculate the
+ * @c begin parameter for any subsequent invocation of the match condition. The
+ * @c second member of the return value is true if a match has been found, false
+ * otherwise.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes in the dynamic buffer sequence's get area that
+ * have been fully consumed by the match function. Returns 0 if an error
+ * occurred.
+ *
+ * @note After a successful read_until operation, the dynamic buffer sequence
+ * may contain additional data beyond that which matched the function object.
+ * An application will typically leave that data in the dynamic buffer sequence
+ * for a subsequent read_until operation to examine.
+ *
+ * @note The default implementation of the @c is_match_condition type trait
+ * evaluates to true for function pointers and function objects with a
+ * @c result_type typedef. It must be specialised for other user-defined
+ * function objects.
+ */
+template <typename SyncReadStream,
+    typename DynamicBuffer, typename MatchCondition>
+std::size_t read_until(SyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    MatchCondition match_condition, boost::system::error_code& ec,
+    typename enable_if<is_match_condition<MatchCondition>::value>::type* = 0);
+
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+
+/// Read data into a streambuf until it contains a specified delimiter.
+/**
+ * This function is used to read data into the specified streambuf until the
+ * streambuf's get area contains the specified delimiter. The call will block
+ * until one of the following conditions is true:
+ *
+ * @li The get area of the streambuf contains the specified delimiter.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the streambuf's get area already contains the
+ * delimiter, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param delim The delimiter character.
+ *
+ * @returns The number of bytes in the streambuf's get area up to and including
+ * the delimiter.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond the delimiter. An application will typically leave
+ * that data in the streambuf for a subsequent read_until operation to examine.
+ *
+ * @par Example
+ * To read data into a streambuf until a newline is encountered:
+ * @code boost::asio::streambuf b;
+ * boost::asio::read_until(s, b, '\n');
+ * std::istream is(&b);
+ * std::string line;
+ * std::getline(is, line); @endcode
+ * After the @c read_until operation completes successfully, the buffer @c b
+ * contains the delimiter:
+ * @code { 'a', 'b', ..., 'c', '\n', 'd', 'e', ... } @endcode
+ * The call to @c std::getline then extracts the data up to and including the
+ * delimiter, so that the string @c line contains:
+ * @code { 'a', 'b', ..., 'c', '\n' } @endcode
+ * The remaining data is left in the buffer @c b as follows:
+ * @code { 'd', 'e', ... } @endcode
+ * This data may be the start of a new line, to be extracted by a subsequent
+ * @c read_until operation.
+ */
+template <typename SyncReadStream, typename Allocator>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, char delim);
+
+/// Read data into a streambuf until it contains a specified delimiter.
+/**
+ * This function is used to read data into the specified streambuf until the
+ * streambuf's get area contains the specified delimiter. The call will block
+ * until one of the following conditions is true:
+ *
+ * @li The get area of the streambuf contains the specified delimiter.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the streambuf's get area already contains the
+ * delimiter, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param delim The delimiter character.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes in the streambuf's get area up to and including
+ * the delimiter. Returns 0 if an error occurred.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond the delimiter. An application will typically leave
+ * that data in the streambuf for a subsequent read_until operation to examine.
+ */
+template <typename SyncReadStream, typename Allocator>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, char delim,
+    boost::system::error_code& ec);
+
+/// Read data into a streambuf until it contains a specified delimiter.
+/**
+ * This function is used to read data into the specified streambuf until the
+ * streambuf's get area contains the specified delimiter. The call will block
+ * until one of the following conditions is true:
+ *
+ * @li The get area of the streambuf contains the specified delimiter.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the streambuf's get area already contains the
+ * delimiter, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param delim The delimiter string.
+ *
+ * @returns The number of bytes in the streambuf's get area up to and including
+ * the delimiter.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond the delimiter. An application will typically leave
+ * that data in the streambuf for a subsequent read_until operation to examine.
+ *
+ * @par Example
+ * To read data into a streambuf until a newline is encountered:
+ * @code boost::asio::streambuf b;
+ * boost::asio::read_until(s, b, "\r\n");
+ * std::istream is(&b);
+ * std::string line;
+ * std::getline(is, line); @endcode
+ * After the @c read_until operation completes successfully, the buffer @c b
+ * contains the delimiter:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } @endcode
+ * The call to @c std::getline then extracts the data up to and including the
+ * delimiter, so that the string @c line contains:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n' } @endcode
+ * The remaining data is left in the buffer @c b as follows:
+ * @code { 'd', 'e', ... } @endcode
+ * This data may be the start of a new line, to be extracted by a subsequent
+ * @c read_until operation.
+ */
+template <typename SyncReadStream, typename Allocator>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_STRING_VIEW_PARAM delim);
+
+/// Read data into a streambuf until it contains a specified delimiter.
+/**
+ * This function is used to read data into the specified streambuf until the
+ * streambuf's get area contains the specified delimiter. The call will block
+ * until one of the following conditions is true:
+ *
+ * @li The get area of the streambuf contains the specified delimiter.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the streambuf's get area already contains the
+ * delimiter, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param delim The delimiter string.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes in the streambuf's get area up to and including
+ * the delimiter. Returns 0 if an error occurred.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond the delimiter. An application will typically leave
+ * that data in the streambuf for a subsequent read_until operation to examine.
+ */
+template <typename SyncReadStream, typename Allocator>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_STRING_VIEW_PARAM delim, boost::system::error_code& ec);
+
+#if defined(BOOST_ASIO_HAS_BOOST_REGEX) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Read data into a streambuf until some part of the data it contains matches
+/// a regular expression.
+/**
+ * This function is used to read data into the specified streambuf until the
+ * streambuf's get area contains some data that matches a regular expression.
+ * The call will block until one of the following conditions is true:
+ *
+ * @li A substring of the streambuf's get area matches the regular expression.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the streambuf's get area already contains data that
+ * matches the regular expression, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param expr The regular expression.
+ *
+ * @returns The number of bytes in the streambuf's get area up to and including
+ * the substring that matches the regular expression.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond that which matched the regular expression. An
+ * application will typically leave that data in the streambuf for a subsequent
+ * read_until operation to examine.
+ *
+ * @par Example
+ * To read data into a streambuf until a CR-LF sequence is encountered:
+ * @code boost::asio::streambuf b;
+ * boost::asio::read_until(s, b, boost::regex("\r\n"));
+ * std::istream is(&b);
+ * std::string line;
+ * std::getline(is, line); @endcode
+ * After the @c read_until operation completes successfully, the buffer @c b
+ * contains the data which matched the regular expression:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } @endcode
+ * The call to @c std::getline then extracts the data up to and including the
+ * match, so that the string @c line contains:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n' } @endcode
+ * The remaining data is left in the buffer @c b as follows:
+ * @code { 'd', 'e', ... } @endcode
+ * This data may be the start of a new line, to be extracted by a subsequent
+ * @c read_until operation.
+ */
+template <typename SyncReadStream, typename Allocator>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr);
+
+/// Read data into a streambuf until some part of the data it contains matches
+/// a regular expression.
+/**
+ * This function is used to read data into the specified streambuf until the
+ * streambuf's get area contains some data that matches a regular expression.
+ * The call will block until one of the following conditions is true:
+ *
+ * @li A substring of the streambuf's get area matches the regular expression.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the streambuf's get area already contains data that
+ * matches the regular expression, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param expr The regular expression.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes in the streambuf's get area up to and including
+ * the substring that matches the regular expression. Returns 0 if an error
+ * occurred.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond that which matched the regular expression. An
+ * application will typically leave that data in the streambuf for a subsequent
+ * read_until operation to examine.
+ */
+template <typename SyncReadStream, typename Allocator>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr,
+    boost::system::error_code& ec);
+
+#endif // defined(BOOST_ASIO_HAS_BOOST_REGEX)
+       // || defined(GENERATING_DOCUMENTATION)
+
+/// Read data into a streambuf until a function object indicates a match.
+/**
+ * This function is used to read data into the specified streambuf until a
+ * user-defined match condition function object, when applied to the data
+ * contained in the streambuf, indicates a successful match. The call will
+ * block until one of the following conditions is true:
+ *
+ * @li The match condition function object returns a std::pair where the second
+ * element evaluates to true.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the match condition function object already indicates
+ * a match, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param match_condition The function object to be called to determine whether
+ * a match exists. The signature of the function object must be:
+ * @code pair<iterator, bool> match_condition(iterator begin, iterator end);
+ * @endcode
+ * where @c iterator represents the type:
+ * @code buffers_iterator<basic_streambuf<Allocator>::const_buffers_type>
+ * @endcode
+ * The iterator parameters @c begin and @c end define the range of bytes to be
+ * scanned to determine whether there is a match. The @c first member of the
+ * return value is an iterator marking one-past-the-end of the bytes that have
+ * been consumed by the match function. This iterator is used to calculate the
+ * @c begin parameter for any subsequent invocation of the match condition. The
+ * @c second member of the return value is true if a match has been found, false
+ * otherwise.
+ *
+ * @returns The number of bytes in the streambuf's get area that have been fully
+ * consumed by the match function.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond that which matched the function object. An application
+ * will typically leave that data in the streambuf for a subsequent read_until
+ * operation to examine.
+ *
+ * @note The default implementation of the @c is_match_condition type trait
+ * evaluates to true for function pointers and function objects with a
+ * @c result_type typedef. It must be specialised for other user-defined
+ * function objects.
+ *
+ * @par Examples
+ * To read data into a streambuf until whitespace is encountered:
+ * @code typedef boost::asio::buffers_iterator<
+ *     boost::asio::streambuf::const_buffers_type> iterator;
+ *
+ * std::pair<iterator, bool>
+ * match_whitespace(iterator begin, iterator end)
+ * {
+ *   iterator i = begin;
+ *   while (i != end)
+ *     if (std::isspace(*i++))
+ *       return std::make_pair(i, true);
+ *   return std::make_pair(i, false);
+ * }
+ * ...
+ * boost::asio::streambuf b;
+ * boost::asio::read_until(s, b, match_whitespace);
+ * @endcode
+ *
+ * To read data into a streambuf until a matching character is found:
+ * @code class match_char
+ * {
+ * public:
+ *   explicit match_char(char c) : c_(c) {}
+ *
+ *   template <typename Iterator>
+ *   std::pair<Iterator, bool> operator()(
+ *       Iterator begin, Iterator end) const
+ *   {
+ *     Iterator i = begin;
+ *     while (i != end)
+ *       if (c_ == *i++)
+ *         return std::make_pair(i, true);
+ *     return std::make_pair(i, false);
+ *   }
+ *
+ * private:
+ *   char c_;
+ * };
+ *
+ * namespace asio {
+ *   template <> struct is_match_condition<match_char>
+ *     : public boost::true_type {};
+ * } // namespace asio
+ * ...
+ * boost::asio::streambuf b;
+ * boost::asio::read_until(s, b, match_char('a'));
+ * @endcode
+ */
+template <typename SyncReadStream, typename Allocator, typename MatchCondition>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b, MatchCondition match_condition,
+    typename enable_if<is_match_condition<MatchCondition>::value>::type* = 0);
+
+/// Read data into a streambuf until a function object indicates a match.
+/**
+ * This function is used to read data into the specified streambuf until a
+ * user-defined match condition function object, when applied to the data
+ * contained in the streambuf, indicates a successful match. The call will
+ * block until one of the following conditions is true:
+ *
+ * @li The match condition function object returns a std::pair where the second
+ * element evaluates to true.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * read_some function. If the match condition function object already indicates
+ * a match, the function returns immediately.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the SyncReadStream concept.
+ *
+ * @param b A streambuf object into which the data will be read.
+ *
+ * @param match_condition The function object to be called to determine whether
+ * a match exists. The signature of the function object must be:
+ * @code pair<iterator, bool> match_condition(iterator begin, iterator end);
+ * @endcode
+ * where @c iterator represents the type:
+ * @code buffers_iterator<basic_streambuf<Allocator>::const_buffers_type>
+ * @endcode
+ * The iterator parameters @c begin and @c end define the range of bytes to be
+ * scanned to determine whether there is a match. The @c first member of the
+ * return value is an iterator marking one-past-the-end of the bytes that have
+ * been consumed by the match function. This iterator is used to calculate the
+ * @c begin parameter for any subsequent invocation of the match condition. The
+ * @c second member of the return value is true if a match has been found, false
+ * otherwise.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes in the streambuf's get area that have been fully
+ * consumed by the match function. Returns 0 if an error occurred.
+ *
+ * @note After a successful read_until operation, the streambuf may contain
+ * additional data beyond that which matched the function object. An application
+ * will typically leave that data in the streambuf for a subsequent read_until
+ * operation to examine.
+ *
+ * @note The default implementation of the @c is_match_condition type trait
+ * evaluates to true for function pointers and function objects with a
+ * @c result_type typedef. It must be specialised for other user-defined
+ * function objects.
+ */
+template <typename SyncReadStream, typename Allocator, typename MatchCondition>
+std::size_t read_until(SyncReadStream& s,
+    boost::asio::basic_streambuf<Allocator>& b,
+    MatchCondition match_condition, boost::system::error_code& ec,
+    typename enable_if<is_match_condition<MatchCondition>::value>::type* = 0);
+
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
+/*@}*/
+/**
+ * @defgroup async_read_until boost::asio::async_read_until
+ *
+ * @brief Start an asynchronous operation to read data into a dynamic buffer
+ * sequence, or into a streambuf, until it contains a delimiter, matches a
+ * regular expression, or a function object indicates a match.
+ */
+/*@{*/
+
+/// Start an asynchronous operation to read data into a dynamic buffer sequence
+/// until it contains a specified delimiter.
+/**
+ * This function is used to asynchronously read data into the specified dynamic
+ * buffer sequence until the dynamic buffer sequence's get area contains the
+ * specified delimiter. The function call always returns immediately. The
+ * asynchronous operation will continue until one of the following conditions
+ * is true:
+ *
+ * @li The get area of the dynamic buffer sequence contains the specified
+ * delimiter.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * async_read_some function, and is known as a <em>composed operation</em>. If
+ * the dynamic buffer sequence's get area already contains the delimiter, this
+ * asynchronous operation completes immediately. The program must ensure that
+ * the stream performs no other read operations (such as async_read,
+ * async_read_until, the stream's async_read_some function, or any other
+ * composed operations that perform reads) until this operation completes.
+ *
+ * @param s The stream from which the data is to be read. The type must support
+ * the AsyncReadStream concept.
+ *
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called.
+ *
+ * @param delim The delimiter character.
+ *
+ * @param handler The handler to be called when the read operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   // Result of operation.
+ *   const boost::system::error_code& error,
+ *
+ *   // The number of bytes in the dynamic buffer sequence's
+ *   // get area up to and including the delimiter.
+ *   // 0 if an error occurred.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
+ *
+ * @note After a successful async_read_until operation, the dynamic buffer
+ * sequence may contain additional data beyond the delimiter. An application
+ * will typically leave that data in the dynamic buffer sequence for a
+ * subsequent async_read_until operation to examine.
+ *
+ * @par Example
+ * To asynchronously read data into a @c std::string until a newline is
+ * encountered:
+ * @code std::string data;
+ * ...
+ * void handler(const boost::system::error_code& e, std::size_t size)
+ * {
+ *   if (!e)
+ *   {
+ *     std::string line = data.substr(0, n);
+ *     data.erase(0, n);
+ *     ...
+ *   }
+ * }
+ * ...
+ * boost::asio::async_read_until(s, data, '\n', handler); @endcode
+ * After the @c async_read_until operation completes successfully, the buffer
+ * @c data contains the delimiter:
+ * @code { 'a', 'b', ..., 'c', '\n', 'd', 'e', ... } @endcode
+ * The call to @c substr then extracts the data up to and including the
+ * delimiter, so that the string @c line contains:
+ * @code { 'a', 'b', ..., 'c', '\n' } @endcode
+ * After the call to @c erase, the remaining data is left in the buffer @c data
+ * as follows:
+ * @code { 'd', 'e', ... } @endcode
+ * This data may be the start of a new line, to be extracted by a subsequent
+ * @c async_read_until operation.
+ */
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    char delim, BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
+
+/// Start an asynchronous operation to read data into a dynamic buffer sequence
+/// until it contains a specified delimiter.
 /**
- * This function is used to read data into the specified streambuf until the
- * streambuf's get area contains some data that matches a regular expression.
- * The call will block until one of the following conditions is true:
+ * This function is used to asynchronously read data into the specified dynamic
+ * buffer sequence until the dynamic buffer sequence's get area contains the
+ * specified delimiter. The function call always returns immediately. The
+ * asynchronous operation will continue until one of the following conditions
+ * is true:
  *
- * @li A substring of the streambuf's get area matches the regular expression.
+ * @li The get area of the dynamic buffer sequence contains the specified
+ * delimiter.
  *
  * @li An error occurred.
  *
  * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the streambuf's get area already contains data that
- * matches the regular expression, the function returns immediately.
+ * async_read_some function, and is known as a <em>composed operation</em>. If
+ * the dynamic buffer sequence's get area already contains the delimiter, this
+ * asynchronous operation completes immediately. The program must ensure that
+ * the stream performs no other read operations (such as async_read,
+ * async_read_until, the stream's async_read_some function, or any other
+ * composed operations that perform reads) until this operation completes.
  *
  * @param s The stream from which the data is to be read. The type must support
- * the SyncReadStream concept.
+ * the AsyncReadStream concept.
  *
- * @param b A streambuf object into which the data will be read.
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called.
  *
- * @param expr The regular expression.
+ * @param delim The delimiter string.
  *
- * @returns The number of bytes in the streambuf's get area up to and including
- * the substring that matches the regular expression.
+ * @param handler The handler to be called when the read operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   // Result of operation.
+ *   const boost::system::error_code& error,
  *
- * @throws boost::system::system_error Thrown on failure.
+ *   // The number of bytes in the dynamic buffer sequence's
+ *   // get area up to and including the delimiter.
+ *   // 0 if an error occurred.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
  *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond that which matched the regular expression. An
- * application will typically leave that data in the streambuf for a subsequent
- * read_until operation to examine.
+ * @note After a successful async_read_until operation, the dynamic buffer
+ * sequence may contain additional data beyond the delimiter. An application
+ * will typically leave that data in the dynamic buffer sequence for a
+ * subsequent async_read_until operation to examine.
  *
  * @par Example
- * To read data into a streambuf until a CR-LF sequence is encountered:
- * @code boost::asio::streambuf b;
- * boost::asio::read_until(s, b, boost::regex("\r\n"));
- * std::istream is(&b);
- * std::string line;
- * std::getline(is, line); @endcode
- * After the @c read_until operation completes successfully, the buffer @c b
- * contains the data which matched the regular expression:
+ * To asynchronously read data into a @c std::string until a CR-LF sequence is
+ * encountered:
+ * @code std::string data;
+ * ...
+ * void handler(const boost::system::error_code& e, std::size_t size)
+ * {
+ *   if (!e)
+ *   {
+ *     std::string line = data.substr(0, n);
+ *     data.erase(0, n);
+ *     ...
+ *   }
+ * }
+ * ...
+ * boost::asio::async_read_until(s, data, "\r\n", handler); @endcode
+ * After the @c async_read_until operation completes successfully, the string
+ * @c data contains the delimiter:
  * @code { 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } @endcode
- * The call to @c std::getline then extracts the data up to and including the
- * match, so that the string @c line contains:
+ * The call to @c substr then extracts the data up to and including the
+ * delimiter, so that the string @c line contains:
  * @code { 'a', 'b', ..., 'c', '\r', '\n' } @endcode
- * The remaining data is left in the buffer @c b as follows:
+ * After the call to @c erase, the remaining data is left in the string @c data
+ * as follows:
  * @code { 'd', 'e', ... } @endcode
  * This data may be the start of a new line, to be extracted by a subsequent
- * @c read_until operation.
+ * @c async_read_until operation.
  */
-template <typename SyncReadStream, typename Allocator>
-std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr);
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_STRING_VIEW_PARAM delim,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
 
-/// Read data into a streambuf until some part of the data it contains matches
-/// a regular expression.
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+#if defined(BOOST_ASIO_HAS_BOOST_REGEX) \
+  || defined(GENERATING_DOCUMENTATION)
+
+/// Start an asynchronous operation to read data into a dynamic buffer sequence
+/// until some part of its data matches a regular expression.
 /**
- * This function is used to read data into the specified streambuf until the
- * streambuf's get area contains some data that matches a regular expression.
- * The call will block until one of the following conditions is true:
+ * This function is used to asynchronously read data into the specified dynamic
+ * buffer sequence until the dynamic buffer sequence's get area contains some
+ * data that matches a regular expression. The function call always returns
+ * immediately. The asynchronous operation will continue until one of the
+ * following conditions is true:
  *
- * @li A substring of the streambuf's get area matches the regular expression.
+ * @li A substring of the dynamic buffer sequence's get area matches the regular
+ * expression.
  *
  * @li An error occurred.
  *
  * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the streambuf's get area already contains data that
- * matches the regular expression, the function returns immediately.
+ * async_read_some function, and is known as a <em>composed operation</em>. If
+ * the dynamic buffer sequence's get area already contains data that matches
+ * the regular expression, this asynchronous operation completes immediately.
+ * The program must ensure that the stream performs no other read operations
+ * (such as async_read, async_read_until, the stream's async_read_some
+ * function, or any other composed operations that perform reads) until this
+ * operation completes.
  *
  * @param s The stream from which the data is to be read. The type must support
- * the SyncReadStream concept.
+ * the AsyncReadStream concept.
  *
- * @param b A streambuf object into which the data will be read.
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called.
  *
  * @param expr The regular expression.
  *
- * @param ec Set to indicate what error occurred, if any.
+ * @param handler The handler to be called when the read operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   // Result of operation.
+ *   const boost::system::error_code& error,
  *
- * @returns The number of bytes in the streambuf's get area up to and including
- * the substring that matches the regular expression. Returns 0 if an error
- * occurred.
+ *   // The number of bytes in the dynamic buffer
+ *   // sequence's get area up to and including the
+ *   // substring that matches the regular expression.
+ *   // 0 if an error occurred.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
  *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond that which matched the regular expression. An
- * application will typically leave that data in the streambuf for a subsequent
- * read_until operation to examine.
+ * @note After a successful async_read_until operation, the dynamic buffer
+ * sequence may contain additional data beyond that which matched the regular
+ * expression. An application will typically leave that data in the dynamic
+ * buffer sequence for a subsequent async_read_until operation to examine.
+ *
+ * @par Example
+ * To asynchronously read data into a @c std::string until a CR-LF sequence is
+ * encountered:
+ * @code std::string data;
+ * ...
+ * void handler(const boost::system::error_code& e, std::size_t size)
+ * {
+ *   if (!e)
+ *   {
+ *     std::string line = data.substr(0, n);
+ *     data.erase(0, n);
+ *     ...
+ *   }
+ * }
+ * ...
+ * boost::asio::async_read_until(s, data,
+ *     boost::regex("\r\n"), handler); @endcode
+ * After the @c async_read_until operation completes successfully, the string
+ * @c data contains the data which matched the regular expression:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n', 'd', 'e', ... } @endcode
+ * The call to @c substr then extracts the data up to and including the match,
+ * so that the string @c line contains:
+ * @code { 'a', 'b', ..., 'c', '\r', '\n' } @endcode
+ * After the call to @c erase, the remaining data is left in the string @c data
+ * as follows:
+ * @code { 'd', 'e', ... } @endcode
+ * This data may be the start of a new line, to be extracted by a subsequent
+ * @c async_read_until operation.
  */
-template <typename SyncReadStream, typename Allocator>
-std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const boost::regex& expr,
-    boost::system::error_code& ec);
+template <typename AsyncReadStream,
+    typename DynamicBuffer, typename ReadHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    const boost::regex& expr,
+    BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
 
 #endif // defined(BOOST_ASIO_HAS_BOOST_REGEX)
        // || defined(GENERATING_DOCUMENTATION)
 
-/// Read data into a streambuf until a function object indicates a match.
+/// Start an asynchronous operation to read data into a dynamic buffer sequence
+/// until a function object indicates a match.
 /**
- * This function is used to read data into the specified streambuf until a
- * user-defined match condition function object, when applied to the data
- * contained in the streambuf, indicates a successful match. The call will
- * block until one of the following conditions is true:
+ * This function is used to asynchronously read data into the specified dynamic
+ * buffer sequence until a user-defined match condition function object, when
+ * applied to the data contained in the dynamic buffer sequence, indicates a
+ * successful match. The function call always returns immediately. The
+ * asynchronous operation will continue until one of the following conditions
+ * is true:
  *
  * @li The match condition function object returns a std::pair where the second
  * element evaluates to true.
@@ -357,20 +1290,27 @@ std::size_t read_until(SyncReadStream& s,
  * @li An error occurred.
  *
  * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the match condition function object already indicates
- * a match, the function returns immediately.
+ * async_read_some function, and is known as a <em>composed operation</em>. If
+ * the match condition function object already indicates a match, this
+ * asynchronous operation completes immediately. The program must ensure that
+ * the stream performs no other read operations (such as async_read,
+ * async_read_until, the stream's async_read_some function, or any other
+ * composed operations that perform reads) until this operation completes.
  *
  * @param s The stream from which the data is to be read. The type must support
- * the SyncReadStream concept.
+ * the AsyncReadStream concept.
  *
- * @param b A streambuf object into which the data will be read.
+ * @param buffers The dynamic buffer sequence into which the data will be read.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called.
  *
  * @param match_condition The function object to be called to determine whether
  * a match exists. The signature of the function object must be:
  * @code pair<iterator, bool> match_condition(iterator begin, iterator end);
  * @endcode
  * where @c iterator represents the type:
- * @code buffers_iterator<basic_streambuf<Allocator>::const_buffers_type>
+ * @code buffers_iterator<typename DynamicBuffer::const_buffers_type>
  * @endcode
  * The iterator parameters @c begin and @c end define the range of bytes to be
  * scanned to determine whether there is a match. The @c first member of the
@@ -380,14 +1320,27 @@ std::size_t read_until(SyncReadStream& s,
  * @c second member of the return value is true if a match has been found, false
  * otherwise.
  *
- * @returns The number of bytes in the streambuf's get area that have been fully
- * consumed by the match function.
+ * @param handler The handler to be called when the read operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   // Result of operation.
+ *   const boost::system::error_code& error,
  *
- * @throws boost::system::system_error Thrown on failure.
+ *   // The number of bytes in the dynamic buffer sequence's
+ *   // get area that have been fully consumed by the match
+ *   // function. O if an error occurred.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
  *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond that which matched the function object. An application
- * will typically leave that data in the streambuf for a subsequent
+ * @note After a successful async_read_until operation, the dynamic buffer
+ * sequence may contain additional data beyond that which matched the function
+ * object. An application will typically leave that data in the dynamic buffer
+ * sequence for a subsequent async_read_until operation to examine.
  *
  * @note The default implementation of the @c is_match_condition type trait
  * evaluates to true for function pointers and function objects with a
@@ -395,9 +1348,10 @@ std::size_t read_until(SyncReadStream& s,
  * function objects.
  *
  * @par Examples
- * To read data into a streambuf until whitespace is encountered:
+ * To asynchronously read data into a @c std::string until whitespace is
+ * encountered:
  * @code typedef boost::asio::buffers_iterator<
- *     boost::asio::streambuf::const_buffers_type> iterator;
+ *     boost::asio::const_buffers_1> iterator;
  *
  * std::pair<iterator, bool>
  * match_whitespace(iterator begin, iterator end)
@@ -409,11 +1363,14 @@ std::size_t read_until(SyncReadStream& s,
  *   return std::make_pair(i, false);
  * }
  * ...
- * boost::asio::streambuf b;
- * boost::asio::read_until(s, b, match_whitespace);
+ * void handler(const boost::system::error_code& e, std::size_t size);
+ * ...
+ * std::string data;
+ * boost::asio::async_read_until(s, data, match_whitespace, handler);
  * @endcode
  *
- * To read data into a streambuf until a matching character is found:
+ * To asynchronously read data into a @c std::string until a matching character
+ * is found:
  * @code class match_char
  * {
  * public:
@@ -439,80 +1396,22 @@ std::size_t read_until(SyncReadStream& s,
  *     : public boost::true_type {};
  * } // namespace asio
  * ...
- * boost::asio::streambuf b;
- * boost::asio::read_until(s, b, match_char('a'));
- * @endcode
- */
-template <typename SyncReadStream, typename Allocator, typename MatchCondition>
-std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, MatchCondition match_condition,
-    typename enable_if<is_match_condition<MatchCondition>::value>::type* = 0);
-
-/// Read data into a streambuf until a function object indicates a match.
-/**
- * This function is used to read data into the specified streambuf until a
- * user-defined match condition function object, when applied to the data
- * contained in the streambuf, indicates a successful match. The call will
- * block until one of the following conditions is true:
- *
- * @li The match condition function object returns a std::pair where the second
- * element evaluates to true.
- *
- * @li An error occurred.
- *
- * This operation is implemented in terms of zero or more calls to the stream's
- * read_some function. If the match condition function object already indicates
- * a match, the function returns immediately.
- *
- * @param s The stream from which the data is to be read. The type must support
- * the SyncReadStream concept.
- *
- * @param b A streambuf object into which the data will be read.
- *
- * @param match_condition The function object to be called to determine whether
- * a match exists. The signature of the function object must be:
- * @code pair<iterator, bool> match_condition(iterator begin, iterator end);
- * @endcode
- * where @c iterator represents the type:
- * @code buffers_iterator<basic_streambuf<Allocator>::const_buffers_type>
+ * void handler(const boost::system::error_code& e, std::size_t size);
+ * ...
+ * std::string data;
+ * boost::asio::async_read_until(s, data, match_char('a'), handler);
  * @endcode
- * The iterator parameters @c begin and @c end define the range of bytes to be
- * scanned to determine whether there is a match. The @c first member of the
- * return value is an iterator marking one-past-the-end of the bytes that have
- * been consumed by the match function. This iterator is used to calculate the
- * @c begin parameter for any subsequent invocation of the match condition. The
- * @c second member of the return value is true if a match has been found, false
- * otherwise.
- *
- * @param ec Set to indicate what error occurred, if any.
- *
- * @returns The number of bytes in the streambuf's get area that have been fully
- * consumed by the match function. Returns 0 if an error occurred.
- *
- * @note After a successful read_until operation, the streambuf may contain
- * additional data beyond that which matched the function object. An application
- * will typically leave that data in the streambuf for a subsequent
- *
- * @note The default implementation of the @c is_match_condition type trait
- * evaluates to true for function pointers and function objects with a
- * @c result_type typedef. It must be specialised for other user-defined
- * function objects.
  */
-template <typename SyncReadStream, typename Allocator, typename MatchCondition>
-std::size_t read_until(SyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b,
-    MatchCondition match_condition, boost::system::error_code& ec,
+template <typename AsyncReadStream, typename DynamicBuffer,
+    typename MatchCondition, typename ReadHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+    void (boost::system::error_code, std::size_t))
+async_read_until(AsyncReadStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    MatchCondition match_condition, BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
     typename enable_if<is_match_condition<MatchCondition>::value>::type* = 0);
 
-/*@}*/
-/**
- * @defgroup async_read_until boost::asio::async_read_until
- *
- * @brief Start an asynchronous operation to read data into a streambuf until it
- * contains a delimiter, matches a regular expression, or a function object
- * indicates a match.
- */
-/*@{*/
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Start an asynchronous operation to read data into a streambuf until it
 /// contains a specified delimiter.
@@ -558,7 +1457,7 @@ std::size_t read_until(SyncReadStream& s,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @note After a successful async_read_until operation, the streambuf may
  * contain additional data beyond the delimiter. An application will typically
@@ -643,7 +1542,7 @@ async_read_until(AsyncReadStream& s,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @note After a successful async_read_until operation, the streambuf may
  * contain additional data beyond the delimiter. An application will typically
@@ -681,7 +1580,8 @@ template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
     void (boost::system::error_code, std::size_t))
 async_read_until(AsyncReadStream& s,
-    boost::asio::basic_streambuf<Allocator>& b, const std::string& delim,
+    boost::asio::basic_streambuf<Allocator>& b,
+    BOOST_ASIO_STRING_VIEW_PARAM delim,
     BOOST_ASIO_MOVE_ARG(ReadHandler) handler);
 
 #if defined(BOOST_ASIO_HAS_BOOST_REGEX) \
@@ -734,7 +1634,7 @@ async_read_until(AsyncReadStream& s,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @note After a successful async_read_until operation, the streambuf may
  * contain additional data beyond that which matched the regular expression. An
@@ -836,7 +1736,7 @@ async_read_until(AsyncReadStream& s,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @note After a successful async_read_until operation, the streambuf may
  * contain additional data beyond that which matched the function object. An
@@ -911,6 +1811,9 @@ async_read_until(AsyncReadStream& s,
     MatchCondition match_condition, BOOST_ASIO_MOVE_ARG(ReadHandler) handler,
     typename enable_if<is_match_condition<MatchCondition>::value>::type* = 0);
 
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 /*@}*/
 
 } // namespace asio
@@ -920,6 +1823,4 @@ async_read_until(AsyncReadStream& s,
 
 #include <boost/asio/impl/read_until.hpp>
 
-#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
-
 #endif // BOOST_ASIO_READ_UNTIL_HPP
diff --git a/include/boost/asio/seq_packet_socket_service.hpp b/include/boost/asio/seq_packet_socket_service.hpp
index fcccafe5ec..4688f3026a 100644
--- a/include/boost/asio/seq_packet_socket_service.hpp
+++ b/include/boost/asio/seq_packet_socket_service.hpp
@@ -16,11 +16,14 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/null_socket_service.hpp>
@@ -39,7 +42,7 @@ namespace asio {
 template <typename Protocol>
 class seq_packet_socket_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<
       seq_packet_socket_service<Protocol> >
@@ -48,7 +51,7 @@ class seq_packet_socket_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The protocol type.
@@ -75,13 +78,6 @@ class seq_packet_socket_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native socket type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef typename service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native socket type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -90,11 +86,11 @@ class seq_packet_socket_service
 #endif
 
   /// Construct a new sequenced packet socket service for the specified
-  /// io_service.
-  explicit seq_packet_socket_service(boost::asio::io_service& io_service)
+  /// io_context.
+  explicit seq_packet_socket_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        seq_packet_socket_service<Protocol> >(io_service),
-      service_impl_(io_service)
+        seq_packet_socket_service<Protocol> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -145,22 +141,23 @@ class seq_packet_socket_service
   }
 
   /// Open a sequenced packet socket.
-  boost::system::error_code open(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID open(implementation_type& impl,
       const protocol_type& protocol, boost::system::error_code& ec)
   {
     if (protocol.type() == BOOST_ASIO_OS_DEF(SOCK_SEQPACKET))
       service_impl_.open(impl, protocol, ec);
     else
       ec = boost::asio::error::invalid_argument;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native socket to a sequenced packet socket.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const protocol_type& protocol, const native_handle_type& native_socket,
       boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, protocol, native_socket, ec);
+    service_impl_.assign(impl, protocol, native_socket, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is open.
@@ -170,16 +167,18 @@ class seq_packet_socket_service
   }
 
   /// Close a sequenced packet socket implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  /// (Deprecated: Use native_handle().) Get the native socket implementation.
-  native_type native(implementation_type& impl)
+  /// Release ownership of the underlying socket.
+  native_handle_type release(implementation_type& impl,
+      boost::system::error_code& ec)
   {
-    return service_impl_.native_handle(impl);
+    return service_impl_.release(impl, ec);
   }
 
   /// Get the native socket implementation.
@@ -189,10 +188,11 @@ class seq_packet_socket_service
   }
 
   /// Cancel all asynchronous operations associated with the socket.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is at the out-of-band data mark.
@@ -210,17 +210,19 @@ class seq_packet_socket_service
   }
 
   /// Bind the sequenced packet socket to the specified local endpoint.
-  boost::system::error_code bind(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID bind(implementation_type& impl,
       const endpoint_type& endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.bind(impl, endpoint, ec);
+    service_impl_.bind(impl, endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Connect the sequenced packet socket to the specified endpoint.
-  boost::system::error_code connect(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID connect(implementation_type& impl,
       const endpoint_type& peer_endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.connect(impl, peer_endpoint, ec);
+    service_impl_.connect(impl, peer_endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous connect.
@@ -231,37 +233,39 @@ class seq_packet_socket_service
       const endpoint_type& peer_endpoint,
       BOOST_ASIO_MOVE_ARG(ConnectHandler) handler)
   {
-    detail::async_result_init<
-      ConnectHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(ConnectHandler)(handler));
+    async_completion<ConnectHandler,
+      void (boost::system::error_code)> init(handler);
 
-    service_impl_.async_connect(impl, peer_endpoint, init.handler);
+    service_impl_.async_connect(impl, peer_endpoint, init.completion_handler);
 
     return init.result.get();
   }
 
   /// Set a socket option.
   template <typename SettableSocketOption>
-  boost::system::error_code set_option(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID set_option(implementation_type& impl,
       const SettableSocketOption& option, boost::system::error_code& ec)
   {
-    return service_impl_.set_option(impl, option, ec);
+    service_impl_.set_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get a socket option.
   template <typename GettableSocketOption>
-  boost::system::error_code get_option(const implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID get_option(const implementation_type& impl,
       GettableSocketOption& option, boost::system::error_code& ec) const
   {
-    return service_impl_.get_option(impl, option, ec);
+    service_impl_.get_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the socket.
   template <typename IoControlCommand>
-  boost::system::error_code io_control(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID io_control(implementation_type& impl,
       IoControlCommand& command, boost::system::error_code& ec)
   {
-    return service_impl_.io_control(impl, command, ec);
+    service_impl_.io_control(impl, command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the socket.
@@ -271,10 +275,11 @@ class seq_packet_socket_service
   }
 
   /// Sets the non-blocking mode of the socket.
-  boost::system::error_code non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.non_blocking(impl, mode, ec);
+    service_impl_.non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native socket implementation.
@@ -284,10 +289,11 @@ class seq_packet_socket_service
   }
 
   /// Sets the non-blocking mode of the native socket implementation.
-  boost::system::error_code native_non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.native_non_blocking(impl, mode, ec);
+    service_impl_.native_non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the local endpoint.
@@ -305,10 +311,36 @@ class seq_packet_socket_service
   }
 
   /// Disable sends or receives on the socket.
-  boost::system::error_code shutdown(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID shutdown(implementation_type& impl,
       socket_base::shutdown_type what, boost::system::error_code& ec)
   {
-    return service_impl_.shutdown(impl, what, ec);
+    service_impl_.shutdown(impl, what, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the socket to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  BOOST_ASIO_SYNC_OP_VOID wait(implementation_type& impl,
+      socket_base::wait_type w, boost::system::error_code& ec)
+  {
+    service_impl_.wait(impl, w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the socket to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(implementation_type& impl, socket_base::wait_type w,
+      BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    service_impl_.async_wait(impl, w, init.completion_handler);
+
+    return init.result.get();
   }
 
   /// Send the given data to the peer.
@@ -329,11 +361,10 @@ class seq_packet_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_send(impl, buffers, flags, init.handler);
+    service_impl_.async_send(impl, buffers, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -357,21 +388,20 @@ class seq_packet_socket_service
       socket_base::message_flags& out_flags,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     service_impl_.async_receive_with_flags(impl,
-        buffers, in_flags, out_flags, init.handler);
+        buffers, in_flags, out_flags, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -383,4 +413,6 @@ class seq_packet_socket_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_SEQ_PACKET_SOCKET_SERVICE_HPP
diff --git a/include/boost/asio/serial_port.hpp b/include/boost/asio/serial_port.hpp
index f3b6fb2450..72a52a52b7 100644
--- a/include/boost/asio/serial_port.hpp
+++ b/include/boost/asio/serial_port.hpp
@@ -21,17 +21,750 @@
 #if defined(BOOST_ASIO_HAS_SERIAL_PORT) \
   || defined(GENERATING_DOCUMENTATION)
 
-#include <boost/asio/basic_serial_port.hpp>
+#include <string>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/basic_io_object.hpp>
+#include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/serial_port_base.hpp>
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/basic_serial_port.hpp>
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# if defined(BOOST_ASIO_HAS_IOCP)
+#  include <boost/asio/detail/win_iocp_serial_port_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::win_iocp_serial_port_service
+# else
+#  include <boost/asio/detail/reactive_serial_port_service.hpp>
+#  define BOOST_ASIO_SVC_T detail::reactive_serial_port_service
+# endif
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
-/// Typedef for the typical usage of a serial port.
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+// Typedef for the typical usage of a serial port.
 typedef basic_serial_port<> serial_port;
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+/// Provides serial port functionality.
+/**
+ * The serial_port class provides a wrapper over serial port functionality.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+class serial_port
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>,
+    public serial_port_base
+{
+public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
+  /// The native representation of a serial port.
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef BOOST_ASIO_SVC_T::native_handle_type native_handle_type;
+#endif
+
+  /// A basic_serial_port is always the lowest layer.
+  typedef serial_port lowest_layer_type;
+
+  /// Construct a serial_port without opening it.
+  /**
+   * This constructor creates a serial port without opening it.
+   *
+   * @param io_context The io_context object that the serial port will use to
+   * dispatch handlers for any asynchronous operations performed on the port.
+   */
+  explicit serial_port(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+  }
+
+  /// Construct and open a serial_port.
+  /**
+   * This constructor creates and opens a serial port for the specified device
+   * name.
+   *
+   * @param io_context The io_context object that the serial port will use to
+   * dispatch handlers for any asynchronous operations performed on the port.
+   *
+   * @param device The platform-specific device name for this serial
+   * port.
+   */
+  explicit serial_port(boost::asio::io_context& io_context,
+      const char* device)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().open(this->get_implementation(), device, ec);
+    boost::asio::detail::throw_error(ec, "open");
+  }
+
+  /// Construct and open a serial_port.
+  /**
+   * This constructor creates and opens a serial port for the specified device
+   * name.
+   *
+   * @param io_context The io_context object that the serial port will use to
+   * dispatch handlers for any asynchronous operations performed on the port.
+   *
+   * @param device The platform-specific device name for this serial
+   * port.
+   */
+  explicit serial_port(boost::asio::io_context& io_context,
+      const std::string& device)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().open(this->get_implementation(), device, ec);
+    boost::asio::detail::throw_error(ec, "open");
+  }
+
+  /// Construct a serial_port on an existing native serial port.
+  /**
+   * This constructor creates a serial port object to hold an existing native
+   * serial port.
+   *
+   * @param io_context The io_context object that the serial port will use to
+   * dispatch handlers for any asynchronous operations performed on the port.
+   *
+   * @param native_serial_port A native serial port.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  serial_port(boost::asio::io_context& io_context,
+      const native_handle_type& native_serial_port)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(),
+        native_serial_port, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a serial_port from another.
+  /**
+   * This constructor moves a serial port from one object to another.
+   *
+   * @param other The other serial_port object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c serial_port(io_context&) constructor.
+   */
+  serial_port(serial_port&& other)
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
+  {
+  }
+
+  /// Move-assign a serial_port from another.
+  /**
+   * This assignment operator moves a serial port from one object to another.
+   *
+   * @param other The other serial_port object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c serial_port(io_context&) constructor.
+   */
+  serial_port& operator=(serial_port&& other)
+  {
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Destroys the serial port.
+  /**
+   * This function destroys the serial port, cancelling any outstanding
+   * asynchronous wait operations associated with the serial port as if by
+   * calling @c cancel.
+   */
+  ~serial_port()
+  {
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+
+  /// Get a reference to the lowest layer.
+  /**
+   * This function returns a reference to the lowest layer in a stack of
+   * layers. Since a serial_port cannot contain any further layers, it simply
+   * returns a reference to itself.
+   *
+   * @return A reference to the lowest layer in the stack of layers. Ownership
+   * is not transferred to the caller.
+   */
+  lowest_layer_type& lowest_layer()
+  {
+    return *this;
+  }
+
+  /// Get a const reference to the lowest layer.
+  /**
+   * This function returns a const reference to the lowest layer in a stack of
+   * layers. Since a serial_port cannot contain any further layers, it simply
+   * returns a reference to itself.
+   *
+   * @return A const reference to the lowest layer in the stack of layers.
+   * Ownership is not transferred to the caller.
+   */
+  const lowest_layer_type& lowest_layer() const
+  {
+    return *this;
+  }
+
+  /// Open the serial port using the specified device name.
+  /**
+   * This function opens the serial port for the specified device name.
+   *
+   * @param device The platform-specific device name.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void open(const std::string& device)
+  {
+    boost::system::error_code ec;
+    this->get_service().open(this->get_implementation(), device, ec);
+    boost::asio::detail::throw_error(ec, "open");
+  }
+
+  /// Open the serial port using the specified device name.
+  /**
+   * This function opens the serial port using the given platform-specific
+   * device name.
+   *
+   * @param device The platform-specific device name.
+   *
+   * @param ec Set the indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID open(const std::string& device,
+      boost::system::error_code& ec)
+  {
+    this->get_service().open(this->get_implementation(), device, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Assign an existing native serial port to the serial port.
+  /*
+   * This function opens the serial port to hold an existing native serial port.
+   *
+   * @param native_serial_port A native serial port.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void assign(const native_handle_type& native_serial_port)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(),
+        native_serial_port, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+  /// Assign an existing native serial port to the serial port.
+  /*
+   * This function opens the serial port to hold an existing native serial port.
+   *
+   * @param native_serial_port A native serial port.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& native_serial_port,
+      boost::system::error_code& ec)
+  {
+    this->get_service().assign(this->get_implementation(),
+        native_serial_port, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Determine whether the serial port is open.
+  bool is_open() const
+  {
+    return this->get_service().is_open(this->get_implementation());
+  }
+
+  /// Close the serial port.
+  /**
+   * This function is used to close the serial port. Any asynchronous read or
+   * write operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void close()
+  {
+    boost::system::error_code ec;
+    this->get_service().close(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "close");
+  }
+
+  /// Close the serial port.
+  /**
+   * This function is used to close the serial port. Any asynchronous read or
+   * write operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
+  {
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Get the native serial port representation.
+  /**
+   * This function may be used to obtain the underlying representation of the
+   * serial port. This is intended to allow access to native serial port
+   * functionality that is not otherwise provided.
+   */
+  native_handle_type native_handle()
+  {
+    return this->get_service().native_handle(this->get_implementation());
+  }
+
+  /// Cancel all asynchronous operations associated with the serial port.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void cancel()
+  {
+    boost::system::error_code ec;
+    this->get_service().cancel(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "cancel");
+  }
+
+  /// Cancel all asynchronous operations associated with the serial port.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
+  {
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Send a break sequence to the serial port.
+  /**
+   * This function causes a break sequence of platform-specific duration to be
+   * sent out the serial port.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void send_break()
+  {
+    boost::system::error_code ec;
+    this->get_service().send_break(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "send_break");
+  }
+
+  /// Send a break sequence to the serial port.
+  /**
+   * This function causes a break sequence of platform-specific duration to be
+   * sent out the serial port.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID send_break(boost::system::error_code& ec)
+  {
+    this->get_service().send_break(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Set an option on the serial port.
+  /**
+   * This function is used to set an option on the serial port.
+   *
+   * @param option The option value to be set on the serial port.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @sa SettableSerialPortOption @n
+   * boost::asio::serial_port_base::baud_rate @n
+   * boost::asio::serial_port_base::flow_control @n
+   * boost::asio::serial_port_base::parity @n
+   * boost::asio::serial_port_base::stop_bits @n
+   * boost::asio::serial_port_base::character_size
+   */
+  template <typename SettableSerialPortOption>
+  void set_option(const SettableSerialPortOption& option)
+  {
+    boost::system::error_code ec;
+    this->get_service().set_option(this->get_implementation(), option, ec);
+    boost::asio::detail::throw_error(ec, "set_option");
+  }
+
+  /// Set an option on the serial port.
+  /**
+   * This function is used to set an option on the serial port.
+   *
+   * @param option The option value to be set on the serial port.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @sa SettableSerialPortOption @n
+   * boost::asio::serial_port_base::baud_rate @n
+   * boost::asio::serial_port_base::flow_control @n
+   * boost::asio::serial_port_base::parity @n
+   * boost::asio::serial_port_base::stop_bits @n
+   * boost::asio::serial_port_base::character_size
+   */
+  template <typename SettableSerialPortOption>
+  BOOST_ASIO_SYNC_OP_VOID set_option(const SettableSerialPortOption& option,
+      boost::system::error_code& ec)
+  {
+    this->get_service().set_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Get an option from the serial port.
+  /**
+   * This function is used to get the current value of an option on the serial
+   * port.
+   *
+   * @param option The option value to be obtained from the serial port.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @sa GettableSerialPortOption @n
+   * boost::asio::serial_port_base::baud_rate @n
+   * boost::asio::serial_port_base::flow_control @n
+   * boost::asio::serial_port_base::parity @n
+   * boost::asio::serial_port_base::stop_bits @n
+   * boost::asio::serial_port_base::character_size
+   */
+  template <typename GettableSerialPortOption>
+  void get_option(GettableSerialPortOption& option)
+  {
+    boost::system::error_code ec;
+    this->get_service().get_option(this->get_implementation(), option, ec);
+    boost::asio::detail::throw_error(ec, "get_option");
+  }
+
+  /// Get an option from the serial port.
+  /**
+   * This function is used to get the current value of an option on the serial
+   * port.
+   *
+   * @param option The option value to be obtained from the serial port.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @sa GettableSerialPortOption @n
+   * boost::asio::serial_port_base::baud_rate @n
+   * boost::asio::serial_port_base::flow_control @n
+   * boost::asio::serial_port_base::parity @n
+   * boost::asio::serial_port_base::stop_bits @n
+   * boost::asio::serial_port_base::character_size
+   */
+  template <typename GettableSerialPortOption>
+  BOOST_ASIO_SYNC_OP_VOID get_option(GettableSerialPortOption& option,
+      boost::system::error_code& ec)
+  {
+    this->get_service().get_option(this->get_implementation(), option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Write some data to the serial port.
+  /**
+   * This function is used to write data to the serial port. The function call
+   * will block until one or more bytes of the data has been written
+   * successfully, or until an error occurs.
+   *
+   * @param buffers One or more data buffers to be written to the serial port.
+   *
+   * @returns The number of bytes written.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The write_some operation may not transmit all of the data to the
+   * peer. Consider using the @ref write function if you need to ensure that
+   * all data is written before the blocking operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * serial_port.write_some(boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().write_some(
+        this->get_implementation(), buffers, ec);
+    boost::asio::detail::throw_error(ec, "write_some");
+    return s;
+  }
+
+  /// Write some data to the serial port.
+  /**
+   * This function is used to write data to the serial port. The function call
+   * will block until one or more bytes of the data has been written
+   * successfully, or until an error occurs.
+   *
+   * @param buffers One or more data buffers to be written to the serial port.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes written. Returns 0 if an error occurred.
+   *
+   * @note The write_some operation may not transmit all of the data to the
+   * peer. Consider using the @ref write function if you need to ensure that
+   * all data is written before the blocking operation completes.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers,
+      boost::system::error_code& ec)
+  {
+    return this->get_service().write_some(
+        this->get_implementation(), buffers, ec);
+  }
+
+  /// Start an asynchronous write.
+  /**
+   * This function is used to asynchronously write data to the serial port.
+   * The function call always returns immediately.
+   *
+   * @param buffers One or more data buffers to be written to the serial port.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the write operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes written.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The write operation may not transmit all of the data to the peer.
+   * Consider using the @ref async_write function if you need to ensure that all
+   * data is written before the asynchronous operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * serial_port.async_write_some(boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence, typename WriteHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+      void (boost::system::error_code, std::size_t))
+  async_write_some(const ConstBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WriteHandler.
+    BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
+
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_write_some(
+        this->get_implementation(), buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+
+  /// Read some data from the serial port.
+  /**
+   * This function is used to read data from the serial port. The function
+   * call will block until one or more bytes of data has been read successfully,
+   * or until an error occurs.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @returns The number of bytes read.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * serial_port.read_some(boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().read_some(
+        this->get_implementation(), buffers, ec);
+    boost::asio::detail::throw_error(ec, "read_some");
+    return s;
+  }
+
+  /// Read some data from the serial port.
+  /**
+   * This function is used to read data from the serial port. The function
+   * call will block until one or more bytes of data has been read successfully,
+   * or until an error occurs.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes read. Returns 0 if an error occurred.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers,
+      boost::system::error_code& ec)
+  {
+    return this->get_service().read_some(
+        this->get_implementation(), buffers, ec);
+  }
+
+  /// Start an asynchronous read.
+  /**
+   * This function is used to asynchronously read data from the serial port.
+   * The function call always returns immediately.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the read operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes read.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The read operation may not read all of the requested number of bytes.
+   * Consider using the @ref async_read function if you need to ensure that the
+   * requested amount of data is read before the asynchronous operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * serial_port.async_read_some(boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence, typename ReadHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+      void (boost::system::error_code, std::size_t))
+  async_read_some(const MutableBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a ReadHandler.
+    BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
+
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_read_some(
+        this->get_implementation(), buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+};
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 } // namespace asio
 } // namespace boost
 
+#include <boost/asio/detail/pop_options.hpp>
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# undef BOOST_ASIO_SVC_T
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // defined(BOOST_ASIO_HAS_SERIAL_PORT)
        //   || defined(GENERATING_DOCUMENTATION)
 
diff --git a/include/boost/asio/serial_port_base.hpp b/include/boost/asio/serial_port_base.hpp
index 884c7ba95d..b2a8367023 100644
--- a/include/boost/asio/serial_port_base.hpp
+++ b/include/boost/asio/serial_port_base.hpp
@@ -55,10 +55,10 @@ class serial_port_base
   public:
     explicit baud_rate(unsigned int rate = 0);
     unsigned int value() const;
-    BOOST_ASIO_DECL boost::system::error_code store(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID store(
         BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec) const;
-    BOOST_ASIO_DECL boost::system::error_code load(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID load(
         const BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec);
   private:
@@ -75,10 +75,10 @@ class serial_port_base
     enum type { none, software, hardware };
     BOOST_ASIO_DECL explicit flow_control(type t = none);
     type value() const;
-    BOOST_ASIO_DECL boost::system::error_code store(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID store(
         BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec) const;
-    BOOST_ASIO_DECL boost::system::error_code load(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID load(
         const BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec);
   private:
@@ -95,10 +95,10 @@ class serial_port_base
     enum type { none, odd, even };
     BOOST_ASIO_DECL explicit parity(type t = none);
     type value() const;
-    BOOST_ASIO_DECL boost::system::error_code store(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID store(
         BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec) const;
-    BOOST_ASIO_DECL boost::system::error_code load(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID load(
         const BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec);
   private:
@@ -115,10 +115,10 @@ class serial_port_base
     enum type { one, onepointfive, two };
     BOOST_ASIO_DECL explicit stop_bits(type t = one);
     type value() const;
-    BOOST_ASIO_DECL boost::system::error_code store(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID store(
         BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec) const;
-    BOOST_ASIO_DECL boost::system::error_code load(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID load(
         const BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec);
   private:
@@ -134,10 +134,10 @@ class serial_port_base
   public:
     BOOST_ASIO_DECL explicit character_size(unsigned int t = 8);
     unsigned int value() const;
-    BOOST_ASIO_DECL boost::system::error_code store(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID store(
         BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec) const;
-    BOOST_ASIO_DECL boost::system::error_code load(
+    BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID load(
         const BOOST_ASIO_OPTION_STORAGE& storage,
         boost::system::error_code& ec);
   private:
diff --git a/include/boost/asio/serial_port_service.hpp b/include/boost/asio/serial_port_service.hpp
index 20cb288b1b..88a1f16e4a 100644
--- a/include/boost/asio/serial_port_service.hpp
+++ b/include/boost/asio/serial_port_service.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_SERIAL_PORT) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -26,7 +28,7 @@
 #include <boost/asio/detail/reactive_serial_port_service.hpp>
 #include <boost/asio/detail/win_iocp_serial_port_service.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/serial_port_base.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -37,7 +39,7 @@ namespace asio {
 /// Default service implementation for a serial port.
 class serial_port_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<serial_port_service>
 #endif
@@ -45,7 +47,7 @@ class serial_port_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
 private:
@@ -64,13 +66,6 @@ class serial_port_service
   typedef service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native handle type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native handle type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -78,10 +73,10 @@ class serial_port_service
   typedef service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new serial port service for the specified io_service.
-  explicit serial_port_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<serial_port_service>(io_service),
-      service_impl_(io_service)
+  /// Construct a new serial port service for the specified io_context.
+  explicit serial_port_service(boost::asio::io_context& io_context)
+    : boost::asio::detail::service_base<serial_port_service>(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -115,17 +110,19 @@ class serial_port_service
   }
 
   /// Open a serial port.
-  boost::system::error_code open(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID open(implementation_type& impl,
       const std::string& device, boost::system::error_code& ec)
   {
-    return service_impl_.open(impl, device, ec);
+    service_impl_.open(impl, device, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native handle to a serial port.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const native_handle_type& handle, boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, handle, ec);
+    service_impl_.assign(impl, handle, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the handle is open.
@@ -135,16 +132,11 @@ class serial_port_service
   }
 
   /// Close a serial port implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
-  }
-
-  /// (Deprecated: Use native_handle().) Get the native handle implementation.
-  native_type native(implementation_type& impl)
-  {
-    return service_impl_.native_handle(impl);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native handle implementation.
@@ -154,33 +146,37 @@ class serial_port_service
   }
 
   /// Cancel all asynchronous operations associated with the handle.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Set a serial port option.
   template <typename SettableSerialPortOption>
-  boost::system::error_code set_option(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID set_option(implementation_type& impl,
       const SettableSerialPortOption& option, boost::system::error_code& ec)
   {
-    return service_impl_.set_option(impl, option, ec);
+    service_impl_.set_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get a serial port option.
   template <typename GettableSerialPortOption>
-  boost::system::error_code get_option(const implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID get_option(const implementation_type& impl,
       GettableSerialPortOption& option, boost::system::error_code& ec) const
   {
-    return service_impl_.get_option(impl, option, ec);
+    service_impl_.get_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Send a break sequence to the serial port.
-  boost::system::error_code send_break(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID send_break(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.send_break(impl, ec);
+    service_impl_.send_break(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Write the given data to the stream.
@@ -199,11 +195,10 @@ class serial_port_service
       const ConstBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_write_some(impl, buffers, init.handler);
+    service_impl_.async_write_some(impl, buffers, init.completion_handler);
 
     return init.result.get();
   }
@@ -224,20 +219,19 @@ class serial_port_service
       const MutableBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_read_some(impl, buffers, init.handler);
+    service_impl_.async_read_some(impl, buffers, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -252,4 +246,6 @@ class serial_port_service
 #endif // defined(BOOST_ASIO_HAS_SERIAL_PORT)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_SERIAL_PORT_SERVICE_HPP
diff --git a/include/boost/asio/signal_set.hpp b/include/boost/asio/signal_set.hpp
index 422e4fca49..6d724e3fd2 100644
--- a/include/boost/asio/signal_set.hpp
+++ b/include/boost/asio/signal_set.hpp
@@ -16,13 +16,432 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/basic_signal_set.hpp>
+
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/basic_io_object.hpp>
+#include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/basic_signal_set.hpp>
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/detail/signal_set_service.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 namespace boost {
 namespace asio {
 
-/// Typedef for the typical usage of a signal set.
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+// Typedef for the typical usage of a signal set.
 typedef basic_signal_set<> signal_set;
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+/// Provides signal functionality.
+/**
+ * The signal_set class provides the ability to perform an asynchronous wait
+ * for one or more signals to occur.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ *
+ * @par Example
+ * Performing an asynchronous wait:
+ * @code
+ * void handler(
+ *     const boost::system::error_code& error,
+ *     int signal_number)
+ * {
+ *   if (!error)
+ *   {
+ *     // A signal occurred.
+ *   }
+ * }
+ *
+ * ...
+ *
+ * // Construct a signal set registered for process termination.
+ * boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
+ *
+ * // Start an asynchronous wait for one of the signals to occur.
+ * signals.async_wait(handler);
+ * @endcode
+ *
+ * @par Queueing of signal notifications
+ *
+ * If a signal is registered with a signal_set, and the signal occurs when
+ * there are no waiting handlers, then the signal notification is queued. The
+ * next async_wait operation on that signal_set will dequeue the notification.
+ * If multiple notifications are queued, subsequent async_wait operations
+ * dequeue them one at a time. Signal notifications are dequeued in order of
+ * ascending signal number.
+ *
+ * If a signal number is removed from a signal_set (using the @c remove or @c
+ * erase member functions) then any queued notifications for that signal are
+ * discarded.
+ *
+ * @par Multiple registration of signals
+ *
+ * The same signal number may be registered with different signal_set objects.
+ * When the signal occurs, one handler is called for each signal_set object.
+ *
+ * Note that multiple registration only works for signals that are registered
+ * using Asio. The application must not also register a signal handler using
+ * functions such as @c signal() or @c sigaction().
+ *
+ * @par Signal masking on POSIX platforms
+ *
+ * POSIX allows signals to be blocked using functions such as @c sigprocmask()
+ * and @c pthread_sigmask(). For signals to be delivered, programs must ensure
+ * that any signals registered using signal_set objects are unblocked in at
+ * least one thread.
+ */
+class signal_set
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<detail::signal_set_service>
+{
+public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
+  /// Construct a signal set without adding any signals.
+  /**
+   * This constructor creates a signal set without registering for any signals.
+   *
+   * @param io_context The io_context object that the signal set will use to
+   * dispatch handlers for any asynchronous operations performed on the set.
+   */
+  explicit signal_set(boost::asio::io_context& io_context)
+    : basic_io_object<detail::signal_set_service>(io_context)
+  {
+  }
+
+  /// Construct a signal set and add one signal.
+  /**
+   * This constructor creates a signal set and registers for one signal.
+   *
+   * @param io_context The io_context object that the signal set will use to
+   * dispatch handlers for any asynchronous operations performed on the set.
+   *
+   * @param signal_number_1 The signal number to be added.
+   *
+   * @note This constructor is equivalent to performing:
+   * @code boost::asio::signal_set signals(io_context);
+   * signals.add(signal_number_1); @endcode
+   */
+  signal_set(boost::asio::io_context& io_context, int signal_number_1)
+    : basic_io_object<detail::signal_set_service>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().add(this->get_implementation(), signal_number_1, ec);
+    boost::asio::detail::throw_error(ec, "add");
+  }
+
+  /// Construct a signal set and add two signals.
+  /**
+   * This constructor creates a signal set and registers for two signals.
+   *
+   * @param io_context The io_context object that the signal set will use to
+   * dispatch handlers for any asynchronous operations performed on the set.
+   *
+   * @param signal_number_1 The first signal number to be added.
+   *
+   * @param signal_number_2 The second signal number to be added.
+   *
+   * @note This constructor is equivalent to performing:
+   * @code boost::asio::signal_set signals(io_context);
+   * signals.add(signal_number_1);
+   * signals.add(signal_number_2); @endcode
+   */
+  signal_set(boost::asio::io_context& io_context, int signal_number_1,
+      int signal_number_2)
+    : basic_io_object<detail::signal_set_service>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().add(this->get_implementation(), signal_number_1, ec);
+    boost::asio::detail::throw_error(ec, "add");
+    this->get_service().add(this->get_implementation(), signal_number_2, ec);
+    boost::asio::detail::throw_error(ec, "add");
+  }
+
+  /// Construct a signal set and add three signals.
+  /**
+   * This constructor creates a signal set and registers for three signals.
+   *
+   * @param io_context The io_context object that the signal set will use to
+   * dispatch handlers for any asynchronous operations performed on the set.
+   *
+   * @param signal_number_1 The first signal number to be added.
+   *
+   * @param signal_number_2 The second signal number to be added.
+   *
+   * @param signal_number_3 The third signal number to be added.
+   *
+   * @note This constructor is equivalent to performing:
+   * @code boost::asio::signal_set signals(io_context);
+   * signals.add(signal_number_1);
+   * signals.add(signal_number_2);
+   * signals.add(signal_number_3); @endcode
+   */
+  signal_set(boost::asio::io_context& io_context, int signal_number_1,
+      int signal_number_2, int signal_number_3)
+    : basic_io_object<detail::signal_set_service>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().add(this->get_implementation(), signal_number_1, ec);
+    boost::asio::detail::throw_error(ec, "add");
+    this->get_service().add(this->get_implementation(), signal_number_2, ec);
+    boost::asio::detail::throw_error(ec, "add");
+    this->get_service().add(this->get_implementation(), signal_number_3, ec);
+    boost::asio::detail::throw_error(ec, "add");
+  }
+
+  /// Destroys the signal set.
+  /**
+   * This function destroys the signal set, cancelling any outstanding
+   * asynchronous wait operations associated with the signal set as if by
+   * calling @c cancel.
+   */
+  ~signal_set()
+  {
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<detail::signal_set_service>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<detail::signal_set_service>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<detail::signal_set_service>::get_executor();
+  }
+
+  /// Add a signal to a signal_set.
+  /**
+   * This function adds the specified signal to the set. It has no effect if the
+   * signal is already in the set.
+   *
+   * @param signal_number The signal to be added to the set.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void add(int signal_number)
+  {
+    boost::system::error_code ec;
+    this->get_service().add(this->get_implementation(), signal_number, ec);
+    boost::asio::detail::throw_error(ec, "add");
+  }
+
+  /// Add a signal to a signal_set.
+  /**
+   * This function adds the specified signal to the set. It has no effect if the
+   * signal is already in the set.
+   *
+   * @param signal_number The signal to be added to the set.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID add(int signal_number,
+      boost::system::error_code& ec)
+  {
+    this->get_service().add(this->get_implementation(), signal_number, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Remove a signal from a signal_set.
+  /**
+   * This function removes the specified signal from the set. It has no effect
+   * if the signal is not in the set.
+   *
+   * @param signal_number The signal to be removed from the set.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note Removes any notifications that have been queued for the specified
+   * signal number.
+   */
+  void remove(int signal_number)
+  {
+    boost::system::error_code ec;
+    this->get_service().remove(this->get_implementation(), signal_number, ec);
+    boost::asio::detail::throw_error(ec, "remove");
+  }
+
+  /// Remove a signal from a signal_set.
+  /**
+   * This function removes the specified signal from the set. It has no effect
+   * if the signal is not in the set.
+   *
+   * @param signal_number The signal to be removed from the set.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @note Removes any notifications that have been queued for the specified
+   * signal number.
+   */
+  BOOST_ASIO_SYNC_OP_VOID remove(int signal_number,
+      boost::system::error_code& ec)
+  {
+    this->get_service().remove(this->get_implementation(), signal_number, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Remove all signals from a signal_set.
+  /**
+   * This function removes all signals from the set. It has no effect if the set
+   * is already empty.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note Removes all queued notifications.
+   */
+  void clear()
+  {
+    boost::system::error_code ec;
+    this->get_service().clear(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "clear");
+  }
+
+  /// Remove all signals from a signal_set.
+  /**
+   * This function removes all signals from the set. It has no effect if the set
+   * is already empty.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @note Removes all queued notifications.
+   */
+  BOOST_ASIO_SYNC_OP_VOID clear(boost::system::error_code& ec)
+  {
+    this->get_service().clear(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Cancel all operations associated with the signal set.
+  /**
+   * This function forces the completion of any pending asynchronous wait
+   * operations against the signal set. The handler for each cancelled
+   * operation will be invoked with the boost::asio::error::operation_aborted
+   * error code.
+   *
+   * Cancellation does not alter the set of registered signals.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   *
+   * @note If a registered signal occurred before cancel() is called, then the
+   * handlers for asynchronous wait operations will:
+   *
+   * @li have already been invoked; or
+   *
+   * @li have been queued for invocation in the near future.
+   *
+   * These handlers can no longer be cancelled, and therefore are passed an
+   * error code that indicates the successful completion of the wait operation.
+   */
+  void cancel()
+  {
+    boost::system::error_code ec;
+    this->get_service().cancel(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "cancel");
+  }
+
+  /// Cancel all operations associated with the signal set.
+  /**
+   * This function forces the completion of any pending asynchronous wait
+   * operations against the signal set. The handler for each cancelled
+   * operation will be invoked with the boost::asio::error::operation_aborted
+   * error code.
+   *
+   * Cancellation does not alter the set of registered signals.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @note If a registered signal occurred before cancel() is called, then the
+   * handlers for asynchronous wait operations will:
+   *
+   * @li have already been invoked; or
+   *
+   * @li have been queued for invocation in the near future.
+   *
+   * These handlers can no longer be cancelled, and therefore are passed an
+   * error code that indicates the successful completion of the wait operation.
+   */
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
+  {
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Start an asynchronous operation to wait for a signal to be delivered.
+  /**
+   * This function may be used to initiate an asynchronous wait against the
+   * signal set. It always returns immediately.
+   *
+   * For each call to async_wait(), the supplied handler will be called exactly
+   * once. The handler will be called when:
+   *
+   * @li One of the registered signals in the signal set occurs; or
+   *
+   * @li The signal set was cancelled, in which case the handler is passed the
+   * error code boost::asio::error::operation_aborted.
+   *
+   * @param handler The handler to be called when the signal occurs. Copies
+   * will be made of the handler as required. The function signature of the
+   * handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   int signal_number // Indicates which signal occurred.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   */
+  template <typename SignalHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(SignalHandler,
+      void (boost::system::error_code, int))
+  async_wait(BOOST_ASIO_MOVE_ARG(SignalHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a SignalHandler.
+    BOOST_ASIO_SIGNAL_HANDLER_CHECK(SignalHandler, handler) type_check;
+
+    async_completion<SignalHandler,
+      void (boost::system::error_code, int)> init(handler);
+
+    this->get_service().async_wait(this->get_implementation(),
+        init.completion_handler);
+
+    return init.result.get();
+  }
+};
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/signal_set_service.hpp b/include/boost/asio/signal_set_service.hpp
index 632eaf0aca..705b32cc42 100644
--- a/include/boost/asio/signal_set_service.hpp
+++ b/include/boost/asio/signal_set_service.hpp
@@ -16,10 +16,13 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/signal_set_service.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -29,7 +32,7 @@ namespace asio {
 /// Default service implementation for a signal set.
 class signal_set_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<signal_set_service>
 #endif
@@ -37,7 +40,7 @@ class signal_set_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
 public:
@@ -48,10 +51,10 @@ class signal_set_service
   typedef detail::signal_set_service::implementation_type implementation_type;
 #endif
 
-  /// Construct a new signal set service for the specified io_service.
-  explicit signal_set_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<signal_set_service>(io_service),
-      service_impl_(io_service)
+  /// Construct a new signal set service for the specified io_context.
+  explicit signal_set_service(boost::asio::io_context& io_context)
+    : boost::asio::detail::service_base<signal_set_service>(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -68,31 +71,35 @@ class signal_set_service
   }
 
   /// Add a signal to a signal_set.
-  boost::system::error_code add(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID add(implementation_type& impl,
       int signal_number, boost::system::error_code& ec)
   {
-    return service_impl_.add(impl, signal_number, ec);
+    service_impl_.add(impl, signal_number, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Remove a signal to a signal_set.
-  boost::system::error_code remove(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID remove(implementation_type& impl,
       int signal_number, boost::system::error_code& ec)
   {
-    return service_impl_.remove(impl, signal_number, ec);
+    service_impl_.remove(impl, signal_number, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Remove all signals from a signal_set.
-  boost::system::error_code clear(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID clear(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.clear(impl, ec);
+    service_impl_.clear(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Cancel all operations associated with the signal set.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   // Start an asynchronous operation to wait for a signal to be delivered.
@@ -102,26 +109,25 @@ class signal_set_service
   async_wait(implementation_type& impl,
       BOOST_ASIO_MOVE_ARG(SignalHandler) handler)
   {
-    detail::async_result_init<
-      SignalHandler, void (boost::system::error_code, int)> init(
-        BOOST_ASIO_MOVE_CAST(SignalHandler)(handler));
+    async_completion<SignalHandler,
+      void (boost::system::error_code, int)> init(handler);
 
-    service_impl_.async_wait(impl, init.handler);
+    service_impl_.async_wait(impl, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // Perform any fork-related housekeeping.
-  void fork_service(boost::asio::io_service::fork_event event)
+  void notify_fork(boost::asio::io_context::fork_event event)
   {
-    service_impl_.fork_service(event);
+    service_impl_.notify_fork(event);
   }
 
   // The platform-specific implementation.
@@ -133,4 +139,6 @@ class signal_set_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_SIGNAL_SET_SERVICE_HPP
diff --git a/include/boost/asio/socket_acceptor_service.hpp b/include/boost/asio/socket_acceptor_service.hpp
index e00c76c901..34adc178df 100644
--- a/include/boost/asio/socket_acceptor_service.hpp
+++ b/include/boost/asio/socket_acceptor_service.hpp
@@ -16,10 +16,13 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <boost/asio/basic_socket.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/null_socket_service.hpp>
@@ -38,7 +41,7 @@ namespace asio {
 template <typename Protocol>
 class socket_acceptor_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<socket_acceptor_service<Protocol> >
 #endif
@@ -46,7 +49,7 @@ class socket_acceptor_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The protocol type.
@@ -73,13 +76,6 @@ class socket_acceptor_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native acceptor type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef typename service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native acceptor type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -87,11 +83,11 @@ class socket_acceptor_service
   typedef typename service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new socket acceptor service for the specified io_service.
-  explicit socket_acceptor_service(boost::asio::io_service& io_service)
+  /// Construct a new socket acceptor service for the specified io_context.
+  explicit socket_acceptor_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        socket_acceptor_service<Protocol> >(io_service),
-      service_impl_(io_service)
+        socket_acceptor_service<Protocol> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -142,18 +138,20 @@ class socket_acceptor_service
   }
 
   /// Open a new socket acceptor implementation.
-  boost::system::error_code open(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID open(implementation_type& impl,
       const protocol_type& protocol, boost::system::error_code& ec)
   {
-    return service_impl_.open(impl, protocol, ec);
+    service_impl_.open(impl, protocol, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native acceptor to a socket acceptor.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const protocol_type& protocol, const native_handle_type& native_acceptor,
       boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, protocol, native_acceptor, ec);
+    service_impl_.assign(impl, protocol, native_acceptor, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the acceptor is open.
@@ -163,38 +161,43 @@ class socket_acceptor_service
   }
 
   /// Cancel all asynchronous operations associated with the acceptor.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Bind the socket acceptor to the specified local endpoint.
-  boost::system::error_code bind(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID bind(implementation_type& impl,
       const endpoint_type& endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.bind(impl, endpoint, ec);
+    service_impl_.bind(impl, endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Place the socket acceptor into the state where it will listen for new
   /// connections.
-  boost::system::error_code listen(implementation_type& impl, int backlog,
+  BOOST_ASIO_SYNC_OP_VOID listen(implementation_type& impl, int backlog,
       boost::system::error_code& ec)
   {
-    return service_impl_.listen(impl, backlog, ec);
+    service_impl_.listen(impl, backlog, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Close a socket acceptor implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  /// (Deprecated: Use native_handle().) Get the native acceptor implementation.
-  native_type native(implementation_type& impl)
+  /// Release ownership of the underlying acceptor.
+  native_handle_type release(implementation_type& impl,
+      boost::system::error_code& ec)
   {
-    return service_impl_.native_handle(impl);
+    return service_impl_.release(impl, ec);
   }
 
   /// Get the native acceptor implementation.
@@ -205,26 +208,29 @@ class socket_acceptor_service
 
   /// Set a socket option.
   template <typename SettableSocketOption>
-  boost::system::error_code set_option(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID set_option(implementation_type& impl,
       const SettableSocketOption& option, boost::system::error_code& ec)
   {
-    return service_impl_.set_option(impl, option, ec);
+    service_impl_.set_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get a socket option.
   template <typename GettableSocketOption>
-  boost::system::error_code get_option(const implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID get_option(const implementation_type& impl,
       GettableSocketOption& option, boost::system::error_code& ec) const
   {
-    return service_impl_.get_option(impl, option, ec);
+    service_impl_.get_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the socket.
   template <typename IoControlCommand>
-  boost::system::error_code io_control(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID io_control(implementation_type& impl,
       IoControlCommand& command, boost::system::error_code& ec)
   {
-    return service_impl_.io_control(impl, command, ec);
+    service_impl_.io_control(impl, command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the acceptor.
@@ -234,10 +240,11 @@ class socket_acceptor_service
   }
 
   /// Sets the non-blocking mode of the acceptor.
-  boost::system::error_code non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.non_blocking(impl, mode, ec);
+    service_impl_.non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native acceptor implementation.
@@ -247,10 +254,11 @@ class socket_acceptor_service
   }
 
   /// Sets the non-blocking mode of the native acceptor implementation.
-  boost::system::error_code native_non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.native_non_blocking(impl, mode, ec);
+    service_impl_.native_non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the local endpoint.
@@ -260,15 +268,51 @@ class socket_acceptor_service
     return service_impl_.local_endpoint(impl, ec);
   }
 
+  /// Wait for the acceptor to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  BOOST_ASIO_SYNC_OP_VOID wait(implementation_type& impl,
+      socket_base::wait_type w, boost::system::error_code& ec)
+  {
+    service_impl_.wait(impl, w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the acceptor to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(implementation_type& impl, socket_base::wait_type w,
+      BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    service_impl_.async_wait(impl, w, init.completion_handler);
+
+    return init.result.get();
+  }
+
   /// Accept a new connection.
   template <typename Protocol1, typename SocketService>
-  boost::system::error_code accept(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID accept(implementation_type& impl,
       basic_socket<Protocol1, SocketService>& peer,
       endpoint_type* peer_endpoint, boost::system::error_code& ec,
       typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
   {
-    return service_impl_.accept(impl, peer, peer_endpoint, ec);
+    service_impl_.accept(impl, peer, peer_endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Accept a new connection.
+  typename Protocol::socket accept(implementation_type& impl,
+      io_context* peer_io_context, endpoint_type* peer_endpoint,
+      boost::system::error_code& ec)
+  {
+    return service_impl_.accept(impl, peer_io_context, peer_endpoint, ec);
   }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
   /// Start an asynchronous accept.
   template <typename Protocol1, typename SocketService, typename AcceptHandler>
@@ -280,20 +324,40 @@ class socket_acceptor_service
       BOOST_ASIO_MOVE_ARG(AcceptHandler) handler,
       typename enable_if<is_convertible<Protocol, Protocol1>::value>::type* = 0)
   {
-    detail::async_result_init<
-      AcceptHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(AcceptHandler)(handler));
+    async_completion<AcceptHandler,
+      void (boost::system::error_code)> init(handler);
+
+    service_impl_.async_accept(impl,
+        peer, peer_endpoint, init.completion_handler);
+
+    return init.result.get();
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  /// Start an asynchronous accept.
+  template <typename MoveAcceptHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(MoveAcceptHandler,
+      void (boost::system::error_code, typename Protocol::socket))
+  async_accept(implementation_type& impl,
+      boost::asio::io_context* peer_io_context, endpoint_type* peer_endpoint,
+      BOOST_ASIO_MOVE_ARG(MoveAcceptHandler) handler)
+  {
+    async_completion<MoveAcceptHandler,
+      void (boost::system::error_code,
+        typename Protocol::socket)> init(handler);
 
-    service_impl_.async_accept(impl, peer, peer_endpoint, init.handler);
+    service_impl_.async_accept(impl,
+        peer_io_context, peer_endpoint, init.completion_handler);
 
     return init.result.get();
   }
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -305,4 +369,6 @@ class socket_acceptor_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_SOCKET_ACCEPTOR_SERVICE_HPP
diff --git a/include/boost/asio/socket_base.hpp b/include/boost/asio/socket_base.hpp
index 7adbf5abfd..9c7518e68e 100644
--- a/include/boost/asio/socket_base.hpp
+++ b/include/boost/asio/socket_base.hpp
@@ -76,6 +76,22 @@ class socket_base
       message_end_of_record = BOOST_ASIO_OS_DEF(MSG_EOR));
 #endif
 
+  /// Wait types.
+  /**
+   * For use with basic_socket::wait() and basic_socket::async_wait().
+   */
+  enum wait_type
+  {
+    /// Wait for a socket to become ready to read.
+    wait_read,
+
+    /// Wait for a socket to become ready to write.
+    wait_write,
+
+    /// Wait for a socket to have error conditions pending.
+    wait_error
+  };
+
   /// Socket option to permit sending of broadcast messages.
   /**
    * Implements the SOL_SOCKET/SO_BROADCAST socket option.
@@ -83,7 +99,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::udp::socket socket(io_service); 
+   * boost::asio::ip::udp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::broadcast option(true);
    * socket.set_option(option);
@@ -92,7 +108,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::udp::socket socket(io_service); 
+   * boost::asio::ip::udp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::broadcast option;
    * socket.get_option(option);
@@ -117,7 +133,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::debug option(true);
    * socket.set_option(option);
@@ -126,7 +142,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::debug option;
    * socket.get_option(option);
@@ -150,7 +166,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::udp::socket socket(io_service); 
+   * boost::asio::ip::udp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::do_not_route option(true);
    * socket.set_option(option);
@@ -159,7 +175,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::udp::socket socket(io_service); 
+   * boost::asio::ip::udp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::do_not_route option;
    * socket.get_option(option);
@@ -184,7 +200,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::keep_alive option(true);
    * socket.set_option(option);
@@ -193,7 +209,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::keep_alive option;
    * socket.get_option(option);
@@ -217,7 +233,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::send_buffer_size option(8192);
    * socket.set_option(option);
@@ -226,7 +242,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::send_buffer_size option;
    * socket.get_option(option);
@@ -251,7 +267,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::send_low_watermark option(1024);
    * socket.set_option(option);
@@ -260,7 +276,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::send_low_watermark option;
    * socket.get_option(option);
@@ -285,7 +301,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::receive_buffer_size option(8192);
    * socket.set_option(option);
@@ -294,7 +310,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::receive_buffer_size option;
    * socket.get_option(option);
@@ -319,7 +335,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::receive_low_watermark option(1024);
    * socket.set_option(option);
@@ -328,7 +344,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::receive_low_watermark option;
    * socket.get_option(option);
@@ -354,7 +370,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service); 
+   * boost::asio::ip::tcp::acceptor acceptor(io_context); 
    * ...
    * boost::asio::socket_base::reuse_address option(true);
    * acceptor.set_option(option);
@@ -363,7 +379,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service); 
+   * boost::asio::ip::tcp::acceptor acceptor(io_context); 
    * ...
    * boost::asio::socket_base::reuse_address option;
    * acceptor.get_option(option);
@@ -389,7 +405,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::linger option(true, 30);
    * socket.set_option(option);
@@ -398,7 +414,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::linger option;
    * socket.get_option(option);
@@ -417,6 +433,40 @@ class socket_base
       linger;
 #endif
 
+  /// Socket option for putting received out-of-band data inline.
+  /**
+   * Implements the SOL_SOCKET/SO_OOBINLINE socket option.
+   *
+   * @par Examples
+   * Setting the option:
+   * @code
+   * boost::asio::ip::tcp::socket socket(io_context);
+   * ...
+   * boost::asio::socket_base::out_of_band_inline option(true);
+   * socket.set_option(option);
+   * @endcode
+   *
+   * @par
+   * Getting the current option value:
+   * @code
+   * boost::asio::ip::tcp::socket socket(io_context);
+   * ...
+   * boost::asio::socket_base::out_of_band_inline option;
+   * socket.get_option(option);
+   * bool value = option.value();
+   * @endcode
+   *
+   * @par Concepts:
+   * Socket_Option, Boolean_Socket_Option.
+   */
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined out_of_band_inline;
+#else
+  typedef boost::asio::detail::socket_option::boolean<
+    BOOST_ASIO_OS_DEF(SOL_SOCKET), BOOST_ASIO_OS_DEF(SO_OOBINLINE)>
+      out_of_band_inline;
+#endif
+
   /// Socket option to report aborted connections on accept.
   /**
    * Implements a custom socket option that determines whether or not an accept
@@ -426,7 +476,7 @@ class socket_base
    * @par Examples
    * Setting the option:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service); 
+   * boost::asio::ip::tcp::acceptor acceptor(io_context); 
    * ...
    * boost::asio::socket_base::enable_connection_aborted option(true);
    * acceptor.set_option(option);
@@ -435,7 +485,7 @@ class socket_base
    * @par
    * Getting the current option value:
    * @code
-   * boost::asio::ip::tcp::acceptor acceptor(io_service); 
+   * boost::asio::ip::tcp::acceptor acceptor(io_context); 
    * ...
    * boost::asio::socket_base::enable_connection_aborted option;
    * acceptor.get_option(option);
@@ -454,28 +504,6 @@ class socket_base
     enable_connection_aborted;
 #endif
 
-  /// (Deprecated: Use non_blocking().) IO control command to
-  /// set the blocking mode of the socket.
-  /**
-   * Implements the FIONBIO IO control command.
-   *
-   * @par Example
-   * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
-   * ...
-   * boost::asio::socket_base::non_blocking_io command(true);
-   * socket.io_control(command);
-   * @endcode
-   *
-   * @par Concepts:
-   * IO_Control_Command, Boolean_IO_Control_Command.
-   */
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined non_blocking_io;
-#else
-  typedef boost::asio::detail::io_control::non_blocking_io non_blocking_io;
-#endif
-
   /// IO control command to get the amount of data that can be read without
   /// blocking.
   /**
@@ -483,7 +511,7 @@ class socket_base
    *
    * @par Example
    * @code
-   * boost::asio::ip::tcp::socket socket(io_service); 
+   * boost::asio::ip::tcp::socket socket(io_context); 
    * ...
    * boost::asio::socket_base::bytes_readable command(true);
    * socket.io_control(command);
@@ -500,12 +528,23 @@ class socket_base
 #endif
 
   /// The maximum length of the queue of pending incoming connections.
+#if defined(GENERATING_DOCUMENTATION)
+  static const int max_listen_connections = implementation_defined;
+#else
+  BOOST_ASIO_STATIC_CONSTANT(int, max_listen_connections
+      = BOOST_ASIO_OS_DEF(SOMAXCONN));
+#endif
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use max_listen_connections.) The maximum length of the queue
+  /// of pending incoming connections.
 #if defined(GENERATING_DOCUMENTATION)
   static const int max_connections = implementation_defined;
 #else
   BOOST_ASIO_STATIC_CONSTANT(int, max_connections
       = BOOST_ASIO_OS_DEF(SOMAXCONN));
 #endif
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
 protected:
   /// Protected destructor to prevent deletion through this type.
diff --git a/include/boost/asio/spawn.hpp b/include/boost/asio/spawn.hpp
index 966bd3efcc..093b4ec350 100644
--- a/include/boost/asio/spawn.hpp
+++ b/include/boost/asio/spawn.hpp
@@ -17,9 +17,13 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <boost/coroutine/all.hpp>
-#include <boost/asio/detail/weak_ptr.hpp>
+#include <boost/asio/bind_executor.hpp>
+#include <boost/asio/detail/memory.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/detail/wrapped_handler.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/executor.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/is_executor.hpp>
 #include <boost/asio/strand.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -95,6 +99,19 @@ class basic_yield_context
   {
   }
 
+  /// Construct a yield context from another yield context type.
+  /**
+   * Requires that OtherHandler be convertible to Handler.
+   */
+  template <typename OtherHandler>
+  basic_yield_context(const basic_yield_context<OtherHandler>& other)
+    : coro_(other.coro_),
+      ca_(other.ca_),
+      handler_(other.handler_),
+      ec_(other.ec_)
+  {
+  }
+
   /// Return a yield context that sets the specified error_code.
   /**
    * By default, when a yield context is used with an asynchronous operation, a
@@ -126,7 +143,7 @@ class basic_yield_context
 #endif // defined(GENERATING_DOCUMENTATION)
   detail::weak_ptr<callee_type> coro_;
   caller_type& ca_;
-  Handler& handler_;
+  Handler handler_;
   boost::system::error_code* ec_;
 };
 
@@ -135,9 +152,7 @@ class basic_yield_context
 typedef basic_yield_context<unspecified> yield_context;
 #else // defined(GENERATING_DOCUMENTATION)
 typedef basic_yield_context<
-  detail::wrapped_handler<
-    io_service::strand, void(*)(),
-    detail::is_continuation_if_running> > yield_context;
+  executor_binder<void(*)(), executor> > yield_context;
 #endif // defined(GENERATING_DOCUMENTATION)
 
 /**
@@ -176,6 +191,21 @@ typedef basic_yield_context<
  */
 /*@{*/
 
+/// Start a new stackful coroutine, calling the specified handler when it
+/// completes.
+/**
+ * This function is used to launch a new coroutine.
+ *
+ * @param function The coroutine function. The function must have the signature:
+ * @code void function(basic_yield_context<Handler> yield); @endcode
+ *
+ * @param attributes Boost.Coroutine attributes used to customise the coroutine.
+ */
+template <typename Function>
+void spawn(BOOST_ASIO_MOVE_ARG(Function) function,
+    const boost::coroutines::attributes& attributes
+      = boost::coroutines::attributes());
+
 /// Start a new stackful coroutine, calling the specified handler when it
 /// completes.
 /**
@@ -195,7 +225,9 @@ template <typename Handler, typename Function>
 void spawn(BOOST_ASIO_MOVE_ARG(Handler) handler,
     BOOST_ASIO_MOVE_ARG(Function) function,
     const boost::coroutines::attributes& attributes
-      = boost::coroutines::attributes());
+      = boost::coroutines::attributes(),
+    typename enable_if<!is_executor<typename decay<Handler>::type>::value &&
+      !is_convertible<Handler&, execution_context&>::value>::type* = 0);
 
 /// Start a new stackful coroutine, inheriting the execution context of another.
 /**
@@ -218,31 +250,49 @@ void spawn(basic_yield_context<Handler> ctx,
     const boost::coroutines::attributes& attributes
       = boost::coroutines::attributes());
 
-/// Start a new stackful coroutine that executes in the context of a strand.
+/// Start a new stackful coroutine that executes on a given executor.
 /**
  * This function is used to launch a new coroutine.
  *
- * @param strand Identifies a strand. By starting multiple coroutines on the
- * same strand, the implementation ensures that none of those coroutines can
- * execute simultaneously.
+ * @param ex Identifies the executor that will run the coroutine. The new
+ * coroutine is implicitly given its own strand within this executor.
  *
  * @param function The coroutine function. The function must have the signature:
  * @code void function(yield_context yield); @endcode
  *
  * @param attributes Boost.Coroutine attributes used to customise the coroutine.
  */
-template <typename Function>
-void spawn(boost::asio::io_service::strand strand,
+template <typename Function, typename Executor>
+void spawn(const Executor& ex,
+    BOOST_ASIO_MOVE_ARG(Function) function,
+    const boost::coroutines::attributes& attributes
+      = boost::coroutines::attributes(),
+    typename enable_if<is_executor<Executor>::value>::type* = 0);
+
+/// Start a new stackful coroutine that executes on a given strand.
+/**
+ * This function is used to launch a new coroutine.
+ *
+ * @param ex Identifies the strand that will run the coroutine.
+ *
+ * @param function The coroutine function. The function must have the signature:
+ * @code void function(yield_context yield); @endcode
+ *
+ * @param attributes Boost.Coroutine attributes used to customise the coroutine.
+ */
+template <typename Function, typename Executor>
+void spawn(const strand<Executor>& ex,
     BOOST_ASIO_MOVE_ARG(Function) function,
     const boost::coroutines::attributes& attributes
       = boost::coroutines::attributes());
 
-/// Start a new stackful coroutine that executes on a given io_service.
+/// Start a new stackful coroutine that executes in the context of a strand.
 /**
  * This function is used to launch a new coroutine.
  *
- * @param io_service Identifies the io_service that will run the coroutine. The
- * new coroutine is implicitly given its own strand within this io_service.
+ * @param s Identifies a strand. By starting multiple coroutines on the same
+ * strand, the implementation ensures that none of those coroutines can execute
+ * simultaneously.
  *
  * @param function The coroutine function. The function must have the signature:
  * @code void function(yield_context yield); @endcode
@@ -250,11 +300,32 @@ void spawn(boost::asio::io_service::strand strand,
  * @param attributes Boost.Coroutine attributes used to customise the coroutine.
  */
 template <typename Function>
-void spawn(boost::asio::io_service& io_service,
+void spawn(const boost::asio::io_context::strand& s,
     BOOST_ASIO_MOVE_ARG(Function) function,
     const boost::coroutines::attributes& attributes
       = boost::coroutines::attributes());
 
+/// Start a new stackful coroutine that executes on a given execution context.
+/**
+ * This function is used to launch a new coroutine.
+ *
+ * @param ctx Identifies the execution context that will run the coroutine. The
+ * new coroutine is implicitly given its own strand within this execution
+ * context.
+ *
+ * @param function The coroutine function. The function must have the signature:
+ * @code void function(yield_context yield); @endcode
+ *
+ * @param attributes Boost.Coroutine attributes used to customise the coroutine.
+ */
+template <typename Function, typename ExecutionContext>
+void spawn(ExecutionContext& ctx,
+    BOOST_ASIO_MOVE_ARG(Function) function,
+    const boost::coroutines::attributes& attributes
+      = boost::coroutines::attributes(),
+    typename enable_if<is_convertible<
+      ExecutionContext&, execution_context&>::value>::type* = 0);
+
 /*@}*/
 
 } // namespace asio
diff --git a/include/boost/asio/ssl.hpp b/include/boost/asio/ssl.hpp
index f82bdc043d..6fc10a92f3 100644
--- a/include/boost/asio/ssl.hpp
+++ b/include/boost/asio/ssl.hpp
@@ -15,15 +15,12 @@
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
-#include <boost/asio/ssl/basic_context.hpp>
 #include <boost/asio/ssl/context.hpp>
 #include <boost/asio/ssl/context_base.hpp>
-#include <boost/asio/ssl/context_service.hpp>
 #include <boost/asio/ssl/error.hpp>
 #include <boost/asio/ssl/rfc2818_verification.hpp>
 #include <boost/asio/ssl/stream.hpp>
 #include <boost/asio/ssl/stream_base.hpp>
-#include <boost/asio/ssl/stream_service.hpp>
 #include <boost/asio/ssl/verify_context.hpp>
 #include <boost/asio/ssl/verify_mode.hpp>
 
diff --git a/include/boost/asio/ssl/context.hpp b/include/boost/asio/ssl/context.hpp
index 8bab40ab3e..6869c0f011 100644
--- a/include/boost/asio/ssl/context.hpp
+++ b/include/boost/asio/ssl/context.hpp
@@ -17,20 +17,15 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/basic_context.hpp>
-# include <boost/asio/ssl/context_service.hpp>
-#else // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <string>
-# include <boost/asio/buffer.hpp>
-# include <boost/asio/io_service.hpp>
-# include <boost/asio/ssl/context_base.hpp>
-# include <boost/asio/ssl/detail/openssl_types.hpp>
-# include <boost/asio/ssl/detail/openssl_init.hpp>
-# include <boost/asio/ssl/detail/password_callback.hpp>
-# include <boost/asio/ssl/detail/verify_callback.hpp>
-# include <boost/asio/ssl/verify_mode.hpp>
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <string>
+#include <boost/asio/buffer.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/ssl/context_base.hpp>
+#include <boost/asio/ssl/detail/openssl_types.hpp>
+#include <boost/asio/ssl/detail/openssl_init.hpp>
+#include <boost/asio/ssl/detail/password_callback.hpp>
+#include <boost/asio/ssl/detail/verify_callback.hpp>
+#include <boost/asio/ssl/verify_mode.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -38,13 +33,6 @@ namespace boost {
 namespace asio {
 namespace ssl {
 
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-/// Typedef for the typical usage of context.
-typedef basic_context<context_service> context;
-
-#else // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 class context
   : public context_base,
     private noncopyable
@@ -53,15 +41,9 @@ class context
   /// The native handle type of the SSL context.
   typedef SSL_CTX* native_handle_type;
 
-  /// (Deprecated: Use native_handle_type.) The native type of the SSL context.
-  typedef SSL_CTX* impl_type;
-
   /// Constructor.
   BOOST_ASIO_DECL explicit context(method m);
 
-  /// Deprecated constructor taking a reference to an io_service object.
-  BOOST_ASIO_DECL context(boost::asio::io_service&, method m);
-
 #if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
   /// Move-construct a context from another.
   /**
@@ -101,15 +83,6 @@ class context
    */
   BOOST_ASIO_DECL native_handle_type native_handle();
 
-  /// (Deprecated: Use native_handle().) Get the underlying implementation in
-  /// the native type.
-  /**
-   * This function may be used to obtain the underlying implementation of the
-   * context. This is intended to allow access to context functionality that is
-   * not otherwise provided.
-   */
-  BOOST_ASIO_DECL impl_type impl();
-
   /// Clear options on the context.
   /**
    * This function may be used to configure the SSL options used by the context.
@@ -136,7 +109,7 @@ class context
    *
    * @note Calls @c SSL_CTX_clear_options.
    */
-  BOOST_ASIO_DECL boost::system::error_code clear_options(options o,
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID clear_options(options o,
       boost::system::error_code& ec);
 
   /// Set options on the context.
@@ -165,7 +138,7 @@ class context
    *
    * @note Calls @c SSL_CTX_set_options.
    */
-  BOOST_ASIO_DECL boost::system::error_code set_options(options o,
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID set_options(options o,
       boost::system::error_code& ec);
 
   /// Set the peer verification mode.
@@ -194,7 +167,7 @@ class context
    *
    * @note Calls @c SSL_CTX_set_verify.
    */
-  BOOST_ASIO_DECL boost::system::error_code set_verify_mode(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID set_verify_mode(
       verify_mode v, boost::system::error_code& ec);
 
   /// Set the peer verification depth.
@@ -223,7 +196,7 @@ class context
    *
    * @note Calls @c SSL_CTX_set_verify_depth.
    */
-  BOOST_ASIO_DECL boost::system::error_code set_verify_depth(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID set_verify_depth(
       int depth, boost::system::error_code& ec);
 
   /// Set the callback used to verify peer certificates.
@@ -266,7 +239,7 @@ class context
    * @note Calls @c SSL_CTX_set_verify.
    */
   template <typename VerifyCallback>
-  boost::system::error_code set_verify_callback(VerifyCallback callback,
+  BOOST_ASIO_SYNC_OP_VOID set_verify_callback(VerifyCallback callback,
       boost::system::error_code& ec);
 
   /// Load a certification authority file for performing verification.
@@ -295,7 +268,7 @@ class context
    *
    * @note Calls @c SSL_CTX_load_verify_locations.
    */
-  BOOST_ASIO_DECL boost::system::error_code load_verify_file(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID load_verify_file(
       const std::string& filename, boost::system::error_code& ec);
 
   /// Add certification authority for performing verification.
@@ -324,7 +297,7 @@ class context
    *
    * @note Calls @c SSL_CTX_get_cert_store and @c X509_STORE_add_cert.
    */
-  BOOST_ASIO_DECL boost::system::error_code add_certificate_authority(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID add_certificate_authority(
       const const_buffer& ca, boost::system::error_code& ec);
 
   /// Configures the context to use the default directories for finding
@@ -351,7 +324,7 @@ class context
    *
    * @note Calls @c SSL_CTX_set_default_verify_paths.
    */
-  BOOST_ASIO_DECL boost::system::error_code set_default_verify_paths(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID set_default_verify_paths(
       boost::system::error_code& ec);
 
   /// Add a directory containing certificate authority files to be used for
@@ -384,7 +357,7 @@ class context
    *
    * @note Calls @c SSL_CTX_load_verify_locations.
    */
-  BOOST_ASIO_DECL boost::system::error_code add_verify_path(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID add_verify_path(
       const std::string& path, boost::system::error_code& ec);
 
   /// Use a certificate from a memory buffer.
@@ -414,7 +387,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_certificate or SSL_CTX_use_certificate_ASN1.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_certificate(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_certificate(
       const const_buffer& certificate, file_format format,
       boost::system::error_code& ec);
 
@@ -445,7 +418,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_certificate_file.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_certificate_file(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_certificate_file(
       const std::string& filename, file_format format,
       boost::system::error_code& ec);
 
@@ -475,7 +448,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_certificate and SSL_CTX_add_extra_chain_cert.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_certificate_chain(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_certificate_chain(
       const const_buffer& chain, boost::system::error_code& ec);
 
   /// Use a certificate chain from a file.
@@ -504,7 +477,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_certificate_chain_file.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_certificate_chain_file(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_certificate_chain_file(
       const std::string& filename, boost::system::error_code& ec);
 
   /// Use a private key from a memory buffer.
@@ -534,7 +507,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_PrivateKey or SSL_CTX_use_PrivateKey_ASN1.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_private_key(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_private_key(
       const const_buffer& private_key, file_format format,
       boost::system::error_code& ec);
 
@@ -565,7 +538,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_PrivateKey_file.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_private_key_file(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_private_key_file(
       const std::string& filename, file_format format,
       boost::system::error_code& ec);
 
@@ -598,7 +571,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_RSAPrivateKey or SSL_CTX_use_RSAPrivateKey_ASN1.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_rsa_private_key(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_rsa_private_key(
       const const_buffer& private_key, file_format format,
       boost::system::error_code& ec);
 
@@ -631,7 +604,7 @@ class context
    *
    * @note Calls @c SSL_CTX_use_RSAPrivateKey_file.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_rsa_private_key_file(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_rsa_private_key_file(
       const std::string& filename, file_format format,
       boost::system::error_code& ec);
 
@@ -663,7 +636,7 @@ class context
    *
    * @note Calls @c SSL_CTX_set_tmp_dh.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_tmp_dh(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_tmp_dh(
       const const_buffer& dh, boost::system::error_code& ec);
 
   /// Use the specified file to obtain the temporary Diffie-Hellman parameters.
@@ -692,7 +665,7 @@ class context
    *
    * @note Calls @c SSL_CTX_set_tmp_dh.
    */
-  BOOST_ASIO_DECL boost::system::error_code use_tmp_dh_file(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID use_tmp_dh_file(
       const std::string& filename, boost::system::error_code& ec);
 
   /// Set the password callback.
@@ -733,7 +706,7 @@ class context
    * @note Calls @c SSL_CTX_set_default_passwd_cb.
    */
   template <typename PasswordCallback>
-  boost::system::error_code set_password_callback(PasswordCallback callback,
+  BOOST_ASIO_SYNC_OP_VOID set_password_callback(PasswordCallback callback,
       boost::system::error_code& ec);
 
 private:
@@ -744,7 +717,7 @@ class context
   struct dh_cleanup;
 
   // Helper function used to set a peer certificate verification callback.
-  BOOST_ASIO_DECL boost::system::error_code do_set_verify_callback(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID do_set_verify_callback(
       detail::verify_callback_base* callback, boost::system::error_code& ec);
 
   // Callback used when the SSL implementation wants to verify a certificate.
@@ -752,7 +725,7 @@ class context
       int preverified, X509_STORE_CTX* ctx);
 
   // Helper function used to set a password callback.
-  BOOST_ASIO_DECL boost::system::error_code do_set_password_callback(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID do_set_password_callback(
       detail::password_callback_base* callback, boost::system::error_code& ec);
 
   // Callback used when the SSL implementation wants a password.
@@ -760,7 +733,7 @@ class context
       char* buf, int size, int purpose, void* data);
 
   // Helper function to set the temporary Diffie-Hellman parameters from a BIO.
-  BOOST_ASIO_DECL boost::system::error_code do_use_tmp_dh(
+  BOOST_ASIO_DECL BOOST_ASIO_SYNC_OP_VOID do_use_tmp_dh(
       BIO* bio, boost::system::error_code& ec);
 
   // Helper function to make a BIO from a memory buffer.
@@ -773,8 +746,6 @@ class context
   boost::asio::ssl::detail::openssl_init<> init_;
 };
 
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace ssl
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/ssl/context_service.hpp b/include/boost/asio/ssl/context_service.hpp
deleted file mode 100644
index b0a31f3750..0000000000
--- a/include/boost/asio/ssl/context_service.hpp
+++ /dev/null
@@ -1,42 +0,0 @@
-//
-// ssl/context_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_CONTEXT_SERVICE_HPP
-#define BOOST_ASIO_SSL_CONTEXT_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-  
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/old/context_service.hpp>
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-using boost::asio::ssl::old::context_service;
-
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_CONTEXT_SERVICE_HPP
diff --git a/include/boost/asio/ssl/detail/buffered_handshake_op.hpp b/include/boost/asio/ssl/detail/buffered_handshake_op.hpp
index b40fe5d69d..926e896ae9 100644
--- a/include/boost/asio/ssl/detail/buffered_handshake_op.hpp
+++ b/include/boost/asio/ssl/detail/buffered_handshake_op.hpp
@@ -17,9 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/detail/engine.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/ssl/detail/engine.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -28,8 +26,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 template <typename ConstBufferSequence>
 class buffered_handshake_op
 {
@@ -46,8 +42,27 @@ class buffered_handshake_op
       boost::system::error_code& ec,
       std::size_t& bytes_transferred) const
   {
-    typename ConstBufferSequence::const_iterator iter = buffers_.begin();
-    typename ConstBufferSequence::const_iterator end = buffers_.end();
+    return this->process(eng, ec, bytes_transferred,
+        boost::asio::buffer_sequence_begin(buffers_),
+        boost::asio::buffer_sequence_end(buffers_));
+  }
+
+  template <typename Handler>
+  void call_handler(Handler& handler,
+      const boost::system::error_code& ec,
+      const std::size_t& bytes_transferred) const
+  {
+    handler(ec, bytes_transferred);
+  }
+
+private:
+  template <typename Iterator>
+  engine::want process(engine& eng,
+      boost::system::error_code& ec,
+      std::size_t& bytes_transferred,
+      Iterator begin, Iterator end) const
+  {
+    Iterator iter = begin;
     std::size_t accumulated_size = 0;
 
     for (;;)
@@ -63,9 +78,9 @@ class buffered_handshake_op
         const_buffer buffer(*iter);
 
         // Skip over any buffers which have already been consumed by the engine.
-        if (bytes_transferred >= accumulated_size + buffer_size(buffer))
+        if (bytes_transferred >= accumulated_size + buffer.size())
         {
-          accumulated_size += buffer_size(buffer);
+          accumulated_size += buffer.size();
           ++iter;
           continue;
         }
@@ -78,30 +93,19 @@ class buffered_handshake_op
 
         // Pass the buffer to the engine, and update the bytes transferred to
         // reflect the total number of bytes consumed so far.
-        bytes_transferred += buffer_size(buffer);
+        bytes_transferred += buffer.size();
         buffer = eng.put_input(buffer);
-        bytes_transferred -= buffer_size(buffer);
+        bytes_transferred -= buffer.size();
         break;
       }
     }
   }
 
-  template <typename Handler>
-  void call_handler(Handler& handler,
-      const boost::system::error_code& ec,
-      const std::size_t& bytes_transferred) const
-  {
-    handler(ec, bytes_transferred);
-  }
-
-private:
   stream_base::handshake_type type_;
   ConstBufferSequence buffers_;
   std::size_t total_buffer_size_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/engine.hpp b/include/boost/asio/ssl/detail/engine.hpp
index f31a4a7287..bcd516dc49 100644
--- a/include/boost/asio/ssl/detail/engine.hpp
+++ b/include/boost/asio/ssl/detail/engine.hpp
@@ -17,14 +17,12 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/buffer.hpp>
-# include <boost/asio/detail/static_mutex.hpp>
-# include <boost/asio/ssl/detail/openssl_types.hpp>
-# include <boost/asio/ssl/detail/verify_callback.hpp>
-# include <boost/asio/ssl/stream_base.hpp>
-# include <boost/asio/ssl/verify_mode.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/buffer.hpp>
+#include <boost/asio/detail/static_mutex.hpp>
+#include <boost/asio/ssl/detail/openssl_types.hpp>
+#include <boost/asio/ssl/detail/verify_callback.hpp>
+#include <boost/asio/ssl/stream_base.hpp>
+#include <boost/asio/ssl/verify_mode.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -33,8 +31,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 class engine
 {
 public:
@@ -98,7 +94,7 @@ class engine
       boost::system::error_code& ec, std::size_t& bytes_transferred);
 
   // Get output data to be written to the transport.
-  BOOST_ASIO_DECL boost::asio::mutable_buffers_1 get_output(
+  BOOST_ASIO_DECL boost::asio::mutable_buffer get_output(
       const boost::asio::mutable_buffer& data);
 
   // Put input data that was read from the transport.
@@ -120,9 +116,11 @@ class engine
   BOOST_ASIO_DECL static int verify_callback_function(
       int preverified, X509_STORE_CTX* ctx);
 
+#if (OPENSSL_VERSION_NUMBER < 0x10000000L)
   // The SSL_accept function may not be thread safe. This mutex is used to
   // protect all calls to the SSL_accept function.
   BOOST_ASIO_DECL static boost::asio::detail::static_mutex& accept_mutex();
+#endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
 
   // Perform one operation. Returns >= 0 on success or error, want_read if the
   // operation needs more input, or want_write if it needs to write some output
@@ -150,8 +148,6 @@ class engine
   BIO* ext_bio_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/handshake_op.hpp b/include/boost/asio/ssl/detail/handshake_op.hpp
index dc61b702f0..de947520f3 100644
--- a/include/boost/asio/ssl/detail/handshake_op.hpp
+++ b/include/boost/asio/ssl/detail/handshake_op.hpp
@@ -17,9 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/detail/engine.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/ssl/detail/engine.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -28,8 +26,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 class handshake_op
 {
 public:
@@ -58,8 +54,6 @@ class handshake_op
   stream_base::handshake_type type_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/impl/engine.ipp b/include/boost/asio/ssl/detail/impl/engine.ipp
index f7d869c56d..35852b6ec3 100644
--- a/include/boost/asio/ssl/detail/impl/engine.ipp
+++ b/include/boost/asio/ssl/detail/impl/engine.ipp
@@ -17,13 +17,11 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/detail/throw_error.hpp>
-# include <boost/asio/error.hpp>
-# include <boost/asio/ssl/detail/engine.hpp>
-# include <boost/asio/ssl/error.hpp>
-# include <boost/asio/ssl/verify_context.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/ssl/detail/engine.hpp>
+#include <boost/asio/ssl/error.hpp>
+#include <boost/asio/ssl/verify_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -32,8 +30,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 engine::engine(SSL_CTX* context)
   : ssl_(::SSL_new(context))
 {
@@ -45,7 +41,9 @@ engine::engine(SSL_CTX* context)
     boost::asio::detail::throw_error(ec, "engine");
   }
 
+#if (OPENSSL_VERSION_NUMBER < 0x10000000L)
   accept_mutex().init();
+#endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
 
   ::SSL_set_mode(ssl_, SSL_MODE_ENABLE_PARTIAL_WRITE);
   ::SSL_set_mode(ssl_, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
@@ -146,37 +144,35 @@ engine::want engine::shutdown(boost::system::error_code& ec)
 engine::want engine::write(const boost::asio::const_buffer& data,
     boost::system::error_code& ec, std::size_t& bytes_transferred)
 {
-  if (boost::asio::buffer_size(data) == 0)
+  if (data.size() == 0)
   {
     ec = boost::system::error_code();
     return engine::want_nothing;
   }
 
   return perform(&engine::do_write,
-      const_cast<void*>(boost::asio::buffer_cast<const void*>(data)),
-      boost::asio::buffer_size(data), ec, &bytes_transferred);
+      const_cast<void*>(data.data()),
+      data.size(), ec, &bytes_transferred);
 }
 
 engine::want engine::read(const boost::asio::mutable_buffer& data,
     boost::system::error_code& ec, std::size_t& bytes_transferred)
 {
-  if (boost::asio::buffer_size(data) == 0)
+  if (data.size() == 0)
   {
     ec = boost::system::error_code();
     return engine::want_nothing;
   }
 
-  return perform(&engine::do_read,
-      boost::asio::buffer_cast<void*>(data),
-      boost::asio::buffer_size(data), ec, &bytes_transferred);
+  return perform(&engine::do_read, data.data(),
+      data.size(), ec, &bytes_transferred);
 }
 
-boost::asio::mutable_buffers_1 engine::get_output(
+boost::asio::mutable_buffer engine::get_output(
     const boost::asio::mutable_buffer& data)
 {
   int length = ::BIO_read(ext_bio_,
-      boost::asio::buffer_cast<void*>(data),
-      static_cast<int>(boost::asio::buffer_size(data)));
+      data.data(), static_cast<int>(data.size()));
 
   return boost::asio::buffer(data,
       length > 0 ? static_cast<std::size_t>(length) : 0);
@@ -186,8 +182,7 @@ boost::asio::const_buffer engine::put_input(
     const boost::asio::const_buffer& data)
 {
   int length = ::BIO_write(ext_bio_,
-      boost::asio::buffer_cast<const void*>(data),
-      static_cast<int>(boost::asio::buffer_size(data)));
+      data.data(), static_cast<int>(data.size()));
 
   return boost::asio::buffer(data +
       (length > 0 ? static_cast<std::size_t>(length) : 0));
@@ -223,11 +218,13 @@ const boost::system::error_code& engine::map_error_code(
   return ec;
 }
 
+#if (OPENSSL_VERSION_NUMBER < 0x10000000L)
 boost::asio::detail::static_mutex& engine::accept_mutex()
 {
   static boost::asio::detail::static_mutex mutex = BOOST_ASIO_STATIC_MUTEX_INIT;
   return mutex;
 }
+#endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
 
 engine::want engine::perform(int (engine::* op)(void*, std::size_t),
     void* data, std::size_t length, boost::system::error_code& ec,
@@ -286,7 +283,9 @@ engine::want engine::perform(int (engine::* op)(void*, std::size_t),
 
 int engine::do_accept(void*, std::size_t)
 {
+#if (OPENSSL_VERSION_NUMBER < 0x10000000L)
   boost::asio::detail::static_mutex::scoped_lock lock(accept_mutex());
+#endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
   return ::SSL_accept(ssl_);
 }
 
@@ -315,8 +314,6 @@ int engine::do_write(void* data, std::size_t length)
       length < INT_MAX ? static_cast<int>(length) : INT_MAX);
 }
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/impl/openssl_init.ipp b/include/boost/asio/ssl/detail/impl/openssl_init.ipp
index 725f5a75ee..dd3dd328b5 100644
--- a/include/boost/asio/ssl/detail/impl/openssl_init.ipp
+++ b/include/boost/asio/ssl/detail/impl/openssl_init.ipp
@@ -79,9 +79,8 @@ public:
 #elif (OPENSSL_VERSION_NUMBER < 0x10100000L)
     ::ERR_remove_thread_state(NULL);
 #endif // (OPENSSL_VERSION_NUMBER < 0x10000000L)
-#if !defined(SSL_OP_NO_COMPRESSION) \
-  && (OPENSSL_VERSION_NUMBER >= 0x10002000L) \
-  && (OPENSSL_VERSION_NUMBER < 0x10100000L)
+#if (OPENSSL_VERSION_NUMBER >= 0x10002000L) \
+    && (OPENSSL_VERSION_NUMBER < 0x10100000L)
     ::SSL_COMP_free_compression_methods();
 #endif // (OPENSSL_VERSION_NUMBER >= 0x10002000L)
        // && (OPENSSL_VERSION_NUMBER < 0x10100000L)
diff --git a/include/boost/asio/ssl/detail/io.hpp b/include/boost/asio/ssl/detail/io.hpp
index 3dbe4520ef..ec1464cce8 100644
--- a/include/boost/asio/ssl/detail/io.hpp
+++ b/include/boost/asio/ssl/detail/io.hpp
@@ -17,11 +17,9 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/detail/engine.hpp>
-# include <boost/asio/ssl/detail/stream_core.hpp>
-# include <boost/asio/write.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/ssl/detail/engine.hpp>
+#include <boost/asio/ssl/detail/stream_core.hpp>
+#include <boost/asio/write.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -30,8 +28,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 template <typename Stream, typename Operation>
 std::size_t io(Stream& next_layer, stream_core& core,
     const Operation& op, boost::system::error_code& ec)
@@ -43,7 +39,7 @@ std::size_t io(Stream& next_layer, stream_core& core,
 
     // If the input buffer is empty then we need to read some more data from
     // the underlying transport.
-    if (boost::asio::buffer_size(core.input_) == 0)
+    if (core.input_.size() == 0)
       core.input_ = boost::asio::buffer(core.input_buffer_,
           next_layer.read_some(core.input_buffer_, ec));
 
@@ -143,7 +139,7 @@ class io_op
 
           // If the input buffer already has data in it we can pass it to the
           // engine and then retry the operation immediately.
-          if (boost::asio::buffer_size(core_.input_) != 0)
+          if (core_.input_.size() != 0)
           {
             core_.input_ = core_.engine_.put_input(core_.input_);
             continue;
@@ -153,7 +149,7 @@ class io_op
           // cannot allow more than one read operation at a time on the
           // underlying transport. The pending_read_ timer's expiry is set to
           // pos_infin if a read is in progress, and neg_infin otherwise.
-          if (core_.pending_read_.expires_at() == core_.neg_infin())
+          if (core_.expiry(core_.pending_read_) == core_.neg_infin())
           {
             // Prevent other read operations from being started.
             core_.pending_read_.expires_at(core_.pos_infin());
@@ -180,7 +176,7 @@ class io_op
           // cannot allow more than one write operation at a time on the
           // underlying transport. The pending_write_ timer's expiry is set to
           // pos_infin if a write is in progress, and neg_infin otherwise.
-          if (core_.pending_write_.expires_at() == core_.neg_infin())
+          if (core_.expiry(core_.pending_write_) == core_.neg_infin())
           {
             // Prevent other write operations from being started.
             core_.pending_write_.expires_at(core_.pos_infin());
@@ -206,7 +202,7 @@ class io_op
           // have to keep in mind that this function might be being called from
           // the async operation's initiating function. In this case we're not
           // allowed to call the handler directly. Instead, issue a zero-sized
-          // read so the handler runs "as-if" posted using io_service::post().
+          // read so the handler runs "as-if" posted using io_context::post().
           if (start)
           {
             next_layer_.async_read_some(
@@ -288,7 +284,7 @@ class io_op
   Handler handler_;
 };
 
-template <typename Stream, typename Operation,  typename Handler>
+template <typename Stream, typename Operation, typename Handler>
 inline void* asio_handler_allocate(std::size_t size,
     io_op<Stream, Operation, Handler>* this_handler)
 {
@@ -339,10 +335,37 @@ inline void async_io(Stream& next_layer, stream_core& core,
       boost::system::error_code(), 0, 1);
 }
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
+
+template <typename Stream, typename Operation,
+    typename Handler, typename Allocator>
+struct associated_allocator<
+    ssl::detail::io_op<Stream, Operation, Handler>, Allocator>
+{
+  typedef typename associated_allocator<Handler, Allocator>::type type;
+
+  static type get(const ssl::detail::io_op<Stream, Operation, Handler>& h,
+      const Allocator& a = Allocator()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_allocator<Handler, Allocator>::get(h.handler_, a);
+  }
+};
+
+template <typename Stream, typename Operation,
+    typename Handler, typename Executor>
+struct associated_executor<
+    ssl::detail::io_op<Stream, Operation, Handler>, Executor>
+{
+  typedef typename associated_executor<Handler, Executor>::type type;
+
+  static type get(const ssl::detail::io_op<Stream, Operation, Handler>& h,
+      const Executor& ex = Executor()) BOOST_ASIO_NOEXCEPT
+  {
+    return associated_executor<Handler, Executor>::get(h.handler_, ex);
+  }
+};
+
 } // namespace asio
 } // namespace boost
 
diff --git a/include/boost/asio/ssl/detail/openssl_init.hpp b/include/boost/asio/ssl/detail/openssl_init.hpp
index fd0432e589..d23febd4a6 100644
--- a/include/boost/asio/ssl/detail/openssl_init.hpp
+++ b/include/boost/asio/ssl/detail/openssl_init.hpp
@@ -17,8 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <cstring>
+#include <boost/asio/detail/memory.hpp>
 #include <boost/asio/detail/noncopyable.hpp>
-#include <boost/asio/detail/shared_ptr.hpp>
 #include <boost/asio/ssl/detail/openssl_types.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
diff --git a/include/boost/asio/ssl/detail/password_callback.hpp b/include/boost/asio/ssl/detail/password_callback.hpp
index 5df01946ba..707670c8d4 100644
--- a/include/boost/asio/ssl/detail/password_callback.hpp
+++ b/include/boost/asio/ssl/detail/password_callback.hpp
@@ -17,11 +17,9 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <cstddef>
-# include <string>
-# include <boost/asio/ssl/context_base.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <cstddef>
+#include <string>
+#include <boost/asio/ssl/context_base.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -30,8 +28,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 class password_callback_base
 {
 public:
@@ -62,8 +58,6 @@ class password_callback : public password_callback_base
   PasswordCallback callback_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/read_op.hpp b/include/boost/asio/ssl/detail/read_op.hpp
index f0b5d6ddf9..d465f0ce15 100644
--- a/include/boost/asio/ssl/detail/read_op.hpp
+++ b/include/boost/asio/ssl/detail/read_op.hpp
@@ -17,10 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/detail/buffer_sequence_adapter.hpp>
-# include <boost/asio/ssl/detail/engine.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/ssl/detail/engine.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -29,8 +27,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 template <typename MutableBufferSequence>
 class read_op
 {
@@ -63,8 +59,6 @@ class read_op
   MutableBufferSequence buffers_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/shutdown_op.hpp b/include/boost/asio/ssl/detail/shutdown_op.hpp
index 3a3f761c08..91acc9fb2a 100644
--- a/include/boost/asio/ssl/detail/shutdown_op.hpp
+++ b/include/boost/asio/ssl/detail/shutdown_op.hpp
@@ -17,9 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/detail/engine.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/ssl/detail/engine.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -28,8 +26,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 class shutdown_op
 {
 public:
@@ -50,8 +46,6 @@ class shutdown_op
   }
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/stream_core.hpp b/include/boost/asio/ssl/detail/stream_core.hpp
index 70d1feddbb..95993e5f4e 100644
--- a/include/boost/asio/ssl/detail/stream_core.hpp
+++ b/include/boost/asio/ssl/detail/stream_core.hpp
@@ -17,15 +17,13 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-#  include <boost/asio/deadline_timer.hpp>
-# else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-#  include <boost/asio/steady_timer.hpp>
-# endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
-# include <boost/asio/ssl/detail/engine.hpp>
-# include <boost/asio/buffer.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+# include <boost/asio/deadline_timer.hpp>
+#else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+# include <boost/asio/steady_timer.hpp>
+#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+#include <boost/asio/ssl/detail/engine.hpp>
+#include <boost/asio/buffer.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -34,18 +32,16 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 struct stream_core
 {
   // According to the OpenSSL documentation, this is the buffer size that is
   // sufficient to hold the largest possible TLS record.
   enum { max_tls_record_size = 17 * 1024 };
 
-  stream_core(SSL_CTX* context, boost::asio::io_service& io_service)
+  stream_core(SSL_CTX* context, boost::asio::io_context& io_context)
     : engine_(context),
-      pending_read_(io_service),
-      pending_write_(io_service),
+      pending_read_(io_context),
+      pending_write_(io_context),
       output_buffer_space_(max_tls_record_size),
       output_buffer_(boost::asio::buffer(output_buffer_space_)),
       input_buffer_space_(max_tls_record_size),
@@ -80,6 +76,13 @@ struct stream_core
   {
     return boost::posix_time::pos_infin;
   }
+
+  // Helper function to get a timer's expiry time.
+  static boost::asio::deadline_timer::time_type expiry(
+      const boost::asio::deadline_timer& timer)
+  {
+    return timer.expires_at();
+  }
 #else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
   // Timer used for storing queued read operations.
   boost::asio::steady_timer pending_read_;
@@ -98,26 +101,31 @@ struct stream_core
   {
     return (boost::asio::steady_timer::time_point::max)();
   }
+
+  // Helper function to get a timer's expiry time.
+  static boost::asio::steady_timer::time_point expiry(
+      const boost::asio::steady_timer& timer)
+  {
+    return timer.expiry();
+  }
 #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 
   // Buffer space used to prepare output intended for the transport.
   std::vector<unsigned char> output_buffer_space_;
 
   // A buffer that may be used to prepare output intended for the transport.
-  const boost::asio::mutable_buffers_1 output_buffer_;
+  const boost::asio::mutable_buffer output_buffer_;
 
   // Buffer space used to read input intended for the engine.
   std::vector<unsigned char> input_buffer_space_;
 
   // A buffer that may be used to read input intended for the engine.
-  const boost::asio::mutable_buffers_1 input_buffer_;
+  const boost::asio::mutable_buffer input_buffer_;
 
   // The buffer pointing to the engine's unconsumed input.
   boost::asio::const_buffer input_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/verify_callback.hpp b/include/boost/asio/ssl/detail/verify_callback.hpp
index c4bea7c215..ea1a436b22 100644
--- a/include/boost/asio/ssl/detail/verify_callback.hpp
+++ b/include/boost/asio/ssl/detail/verify_callback.hpp
@@ -17,9 +17,7 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/verify_context.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/ssl/verify_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -28,8 +26,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 class verify_callback_base
 {
 public:
@@ -58,8 +54,6 @@ class verify_callback : public verify_callback_base
   VerifyCallback callback_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/detail/write_op.hpp b/include/boost/asio/ssl/detail/write_op.hpp
index c04eda86d2..b30f0c3787 100644
--- a/include/boost/asio/ssl/detail/write_op.hpp
+++ b/include/boost/asio/ssl/detail/write_op.hpp
@@ -17,10 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/detail/buffer_sequence_adapter.hpp>
-# include <boost/asio/ssl/detail/engine.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/ssl/detail/engine.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -29,8 +27,6 @@ namespace asio {
 namespace ssl {
 namespace detail {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 template <typename ConstBufferSequence>
 class write_op
 {
@@ -63,8 +59,6 @@ class write_op
   ConstBufferSequence buffers_;
 };
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace detail
 } // namespace ssl
 } // namespace asio
diff --git a/include/boost/asio/ssl/impl/context.hpp b/include/boost/asio/ssl/impl/context.hpp
index 52547d0437..a207a73fa7 100644
--- a/include/boost/asio/ssl/impl/context.hpp
+++ b/include/boost/asio/ssl/impl/context.hpp
@@ -18,9 +18,7 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/detail/throw_error.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/detail/throw_error.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -28,8 +26,6 @@ namespace boost {
 namespace asio {
 namespace ssl {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 template <typename VerifyCallback>
 void context::set_verify_callback(VerifyCallback callback)
 {
@@ -39,11 +35,12 @@ void context::set_verify_callback(VerifyCallback callback)
 }
 
 template <typename VerifyCallback>
-boost::system::error_code context::set_verify_callback(
+BOOST_ASIO_SYNC_OP_VOID context::set_verify_callback(
     VerifyCallback callback, boost::system::error_code& ec)
 {
-  return do_set_verify_callback(
+  do_set_verify_callback(
       new detail::verify_callback<VerifyCallback>(callback), ec);
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 template <typename PasswordCallback>
@@ -55,15 +52,14 @@ void context::set_password_callback(PasswordCallback callback)
 }
 
 template <typename PasswordCallback>
-boost::system::error_code context::set_password_callback(
+BOOST_ASIO_SYNC_OP_VOID context::set_password_callback(
     PasswordCallback callback, boost::system::error_code& ec)
 {
-  return do_set_password_callback(
+  do_set_password_callback(
       new detail::password_callback<PasswordCallback>(callback), ec);
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace ssl
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/ssl/impl/context.ipp b/include/boost/asio/ssl/impl/context.ipp
index a1fb9a578b..f50ce454ea 100644
--- a/include/boost/asio/ssl/impl/context.ipp
+++ b/include/boost/asio/ssl/impl/context.ipp
@@ -18,13 +18,11 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <cstring>
-# include <boost/asio/detail/throw_error.hpp>
-# include <boost/asio/error.hpp>
-# include <boost/asio/ssl/context.hpp>
-# include <boost/asio/ssl/error.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <cstring>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/ssl/context.hpp>
+#include <boost/asio/ssl/error.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -32,8 +30,6 @@ namespace boost {
 namespace asio {
 namespace ssl {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 struct context::bio_cleanup
 {
   BIO* p;
@@ -326,14 +322,6 @@ context::context(context::method m)
   set_options(no_compression);
 }
 
-context::context(boost::asio::io_service&, context::method m)
-  : handle_(0)
-{
-  context tmp(m);
-  handle_ = tmp.handle_;
-  tmp.handle_ = 0;
-}
-
 #if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 context::context(context&& other)
 {
@@ -390,11 +378,6 @@ context::native_handle_type context::native_handle()
   return handle_;
 }
 
-context::impl_type context::impl()
-{
-  return handle_;
-}
-
 void context::clear_options(context::options o)
 {
   boost::system::error_code ec;
@@ -402,7 +385,7 @@ void context::clear_options(context::options o)
   boost::asio::detail::throw_error(ec, "clear_options");
 }
 
-boost::system::error_code context::clear_options(
+BOOST_ASIO_SYNC_OP_VOID context::clear_options(
     context::options o, boost::system::error_code& ec)
 {
 #if (OPENSSL_VERSION_NUMBER >= 0x009080DFL) \
@@ -426,7 +409,7 @@ boost::system::error_code context::clear_options(
   ec = boost::asio::error::operation_not_supported;
 #endif // (OPENSSL_VERSION_NUMBER >= 0x009080DFL)
        //   && (OPENSSL_VERSION_NUMBER != 0x00909000L)
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::set_options(context::options o)
@@ -436,7 +419,7 @@ void context::set_options(context::options o)
   boost::asio::detail::throw_error(ec, "set_options");
 }
 
-boost::system::error_code context::set_options(
+BOOST_ASIO_SYNC_OP_VOID context::set_options(
     context::options o, boost::system::error_code& ec)
 {
 #if !defined(SSL_OP_NO_COMPRESSION)
@@ -453,7 +436,7 @@ boost::system::error_code context::set_options(
   ::SSL_CTX_set_options(handle_, o);
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::set_verify_mode(verify_mode v)
@@ -463,13 +446,13 @@ void context::set_verify_mode(verify_mode v)
   boost::asio::detail::throw_error(ec, "set_verify_mode");
 }
 
-boost::system::error_code context::set_verify_mode(
+BOOST_ASIO_SYNC_OP_VOID context::set_verify_mode(
     verify_mode v, boost::system::error_code& ec)
 {
   ::SSL_CTX_set_verify(handle_, v, ::SSL_CTX_get_verify_callback(handle_));
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::set_verify_depth(int depth)
@@ -479,13 +462,13 @@ void context::set_verify_depth(int depth)
   boost::asio::detail::throw_error(ec, "set_verify_depth");
 }
 
-boost::system::error_code context::set_verify_depth(
+BOOST_ASIO_SYNC_OP_VOID context::set_verify_depth(
     int depth, boost::system::error_code& ec)
 {
   ::SSL_CTX_set_verify_depth(handle_, depth);
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::load_verify_file(const std::string& filename)
@@ -495,7 +478,7 @@ void context::load_verify_file(const std::string& filename)
   boost::asio::detail::throw_error(ec, "load_verify_file");
 }
 
-boost::system::error_code context::load_verify_file(
+BOOST_ASIO_SYNC_OP_VOID context::load_verify_file(
     const std::string& filename, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -505,11 +488,11 @@ boost::system::error_code context::load_verify_file(
     ec = boost::system::error_code(
         static_cast<int>(::ERR_get_error()),
         boost::asio::error::get_ssl_category());
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::add_certificate_authority(const const_buffer& ca)
@@ -519,7 +502,7 @@ void context::add_certificate_authority(const const_buffer& ca)
   boost::asio::detail::throw_error(ec, "add_certificate_authority");
 }
 
-boost::system::error_code context::add_certificate_authority(
+BOOST_ASIO_SYNC_OP_VOID context::add_certificate_authority(
     const const_buffer& ca, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -535,7 +518,7 @@ boost::system::error_code context::add_certificate_authority(
         if (::X509_STORE_add_cert(store, cert.p) == 1)
         {
           ec = boost::system::error_code();
-          return ec;
+          BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
         }
       }
     }
@@ -544,7 +527,7 @@ boost::system::error_code context::add_certificate_authority(
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::set_default_verify_paths()
@@ -554,7 +537,7 @@ void context::set_default_verify_paths()
   boost::asio::detail::throw_error(ec, "set_default_verify_paths");
 }
 
-boost::system::error_code context::set_default_verify_paths(
+BOOST_ASIO_SYNC_OP_VOID context::set_default_verify_paths(
     boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -564,11 +547,11 @@ boost::system::error_code context::set_default_verify_paths(
     ec = boost::system::error_code(
         static_cast<int>(::ERR_get_error()),
         boost::asio::error::get_ssl_category());
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::add_verify_path(const std::string& path)
@@ -578,7 +561,7 @@ void context::add_verify_path(const std::string& path)
   boost::asio::detail::throw_error(ec, "add_verify_path");
 }
 
-boost::system::error_code context::add_verify_path(
+BOOST_ASIO_SYNC_OP_VOID context::add_verify_path(
     const std::string& path, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -588,11 +571,11 @@ boost::system::error_code context::add_verify_path(
     ec = boost::system::error_code(
         static_cast<int>(::ERR_get_error()),
         boost::asio::error::get_ssl_category());
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_certificate(
@@ -603,7 +586,7 @@ void context::use_certificate(
   boost::asio::detail::throw_error(ec, "use_certificate");
 }
 
-boost::system::error_code context::use_certificate(
+BOOST_ASIO_SYNC_OP_VOID context::use_certificate(
     const const_buffer& certificate, file_format format,
     boost::system::error_code& ec)
 {
@@ -612,11 +595,11 @@ boost::system::error_code context::use_certificate(
   if (format == context_base::asn1)
   {
     if (::SSL_CTX_use_certificate_ASN1(handle_,
-          static_cast<int>(buffer_size(certificate)),
-          buffer_cast<const unsigned char*>(certificate)) == 1)
+          static_cast<int>(certificate.size()),
+          static_cast<const unsigned char*>(certificate.data())) == 1)
     {
       ec = boost::system::error_code();
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
   }
   else if (format == context_base::pem)
@@ -630,7 +613,7 @@ boost::system::error_code context::use_certificate(
         if (::SSL_CTX_use_certificate(handle_, cert.p) == 1)
         {
           ec = boost::system::error_code();
-          return ec;
+          BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
         }
       }
     }
@@ -638,13 +621,13 @@ boost::system::error_code context::use_certificate(
   else
   {
     ec = boost::asio::error::invalid_argument;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_certificate_file(
@@ -655,7 +638,7 @@ void context::use_certificate_file(
   boost::asio::detail::throw_error(ec, "use_certificate_file");
 }
 
-boost::system::error_code context::use_certificate_file(
+BOOST_ASIO_SYNC_OP_VOID context::use_certificate_file(
     const std::string& filename, file_format format,
     boost::system::error_code& ec)
 {
@@ -671,7 +654,7 @@ boost::system::error_code context::use_certificate_file(
   default:
     {
       ec = boost::asio::error::invalid_argument;
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
   }
 
@@ -682,11 +665,11 @@ boost::system::error_code context::use_certificate_file(
     ec = boost::system::error_code(
         static_cast<int>(::ERR_get_error()),
         boost::asio::error::get_ssl_category());
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_certificate_chain(const const_buffer& chain)
@@ -696,7 +679,7 @@ void context::use_certificate_chain(const const_buffer& chain)
   boost::asio::detail::throw_error(ec, "use_certificate_chain");
 }
 
-boost::system::error_code context::use_certificate_chain(
+BOOST_ASIO_SYNC_OP_VOID context::use_certificate_chain(
     const const_buffer& chain, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -719,7 +702,7 @@ boost::system::error_code context::use_certificate_chain(
     {
       ec = boost::system::error_code(ERR_R_PEM_LIB,
           boost::asio::error::get_ssl_category());
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
 
     int result = ::SSL_CTX_use_certificate(handle_, cert.p);
@@ -728,7 +711,7 @@ boost::system::error_code context::use_certificate_chain(
       ec = boost::system::error_code(
           static_cast<int>(::ERR_get_error()),
           boost::asio::error::get_ssl_category());
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
 
 #if (OPENSSL_VERSION_NUMBER >= 0x10002000L) && !defined(LIBRESSL_VERSION_NUMBER)
@@ -750,7 +733,7 @@ boost::system::error_code context::use_certificate_chain(
         ec = boost::system::error_code(
             static_cast<int>(::ERR_get_error()),
             boost::asio::error::get_ssl_category());
-        return ec;
+        BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
       }
     }
   
@@ -760,14 +743,14 @@ boost::system::error_code context::use_certificate_chain(
     {
       ::ERR_clear_error();
       ec = boost::system::error_code();
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
   }
 
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_certificate_chain_file(const std::string& filename)
@@ -777,7 +760,7 @@ void context::use_certificate_chain_file(const std::string& filename)
   boost::asio::detail::throw_error(ec, "use_certificate_chain_file");
 }
 
-boost::system::error_code context::use_certificate_chain_file(
+BOOST_ASIO_SYNC_OP_VOID context::use_certificate_chain_file(
     const std::string& filename, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -787,11 +770,11 @@ boost::system::error_code context::use_certificate_chain_file(
     ec = boost::system::error_code(
         static_cast<int>(::ERR_get_error()),
         boost::asio::error::get_ssl_category());
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_private_key(
@@ -802,7 +785,7 @@ void context::use_private_key(
   boost::asio::detail::throw_error(ec, "use_private_key");
 }
 
-boost::system::error_code context::use_private_key(
+BOOST_ASIO_SYNC_OP_VOID context::use_private_key(
     const const_buffer& private_key, context::file_format format,
     boost::system::error_code& ec)
 {
@@ -833,7 +816,7 @@ boost::system::error_code context::use_private_key(
     default:
       {
         ec = boost::asio::error::invalid_argument;
-        return ec;
+        BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
       }
     }
 
@@ -842,7 +825,7 @@ boost::system::error_code context::use_private_key(
       if (::SSL_CTX_use_PrivateKey(handle_, evp_private_key.p) == 1)
       {
         ec = boost::system::error_code();
-        return ec;
+        BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
       }
     }
   }
@@ -850,7 +833,7 @@ boost::system::error_code context::use_private_key(
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_private_key_file(
@@ -869,7 +852,7 @@ void context::use_rsa_private_key(
   boost::asio::detail::throw_error(ec, "use_rsa_private_key");
 }
 
-boost::system::error_code context::use_rsa_private_key(
+BOOST_ASIO_SYNC_OP_VOID context::use_rsa_private_key(
     const const_buffer& private_key, context::file_format format,
     boost::system::error_code& ec)
 {
@@ -900,7 +883,7 @@ boost::system::error_code context::use_rsa_private_key(
     default:
       {
         ec = boost::asio::error::invalid_argument;
-        return ec;
+        BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
       }
     }
 
@@ -909,7 +892,7 @@ boost::system::error_code context::use_rsa_private_key(
       if (::SSL_CTX_use_RSAPrivateKey(handle_, rsa_private_key.p) == 1)
       {
         ec = boost::system::error_code();
-        return ec;
+        BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
       }
     }
   }
@@ -917,10 +900,10 @@ boost::system::error_code context::use_rsa_private_key(
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code context::use_private_key_file(
+BOOST_ASIO_SYNC_OP_VOID context::use_private_key_file(
     const std::string& filename, context::file_format format,
     boost::system::error_code& ec)
 {
@@ -936,7 +919,7 @@ boost::system::error_code context::use_private_key_file(
   default:
     {
       ec = boost::asio::error::invalid_argument;
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
   }
 
@@ -947,11 +930,11 @@ boost::system::error_code context::use_private_key_file(
     ec = boost::system::error_code(
         static_cast<int>(::ERR_get_error()),
         boost::asio::error::get_ssl_category());
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_rsa_private_key_file(
@@ -962,7 +945,7 @@ void context::use_rsa_private_key_file(
   boost::asio::detail::throw_error(ec, "use_rsa_private_key_file");
 }
 
-boost::system::error_code context::use_rsa_private_key_file(
+BOOST_ASIO_SYNC_OP_VOID context::use_rsa_private_key_file(
     const std::string& filename, context::file_format format,
     boost::system::error_code& ec)
 {
@@ -978,7 +961,7 @@ boost::system::error_code context::use_rsa_private_key_file(
   default:
     {
       ec = boost::asio::error::invalid_argument;
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
   }
 
@@ -990,11 +973,11 @@ boost::system::error_code context::use_rsa_private_key_file(
     ec = boost::system::error_code(
         static_cast<int>(::ERR_get_error()),
         boost::asio::error::get_ssl_category());
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_tmp_dh(const const_buffer& dh)
@@ -1004,7 +987,7 @@ void context::use_tmp_dh(const const_buffer& dh)
   boost::asio::detail::throw_error(ec, "use_tmp_dh");
 }
 
-boost::system::error_code context::use_tmp_dh(
+BOOST_ASIO_SYNC_OP_VOID context::use_tmp_dh(
     const const_buffer& dh, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -1018,7 +1001,7 @@ boost::system::error_code context::use_tmp_dh(
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 void context::use_tmp_dh_file(const std::string& filename)
@@ -1028,7 +1011,7 @@ void context::use_tmp_dh_file(const std::string& filename)
   boost::asio::detail::throw_error(ec, "use_tmp_dh_file");
 }
 
-boost::system::error_code context::use_tmp_dh_file(
+BOOST_ASIO_SYNC_OP_VOID context::use_tmp_dh_file(
     const std::string& filename, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -1042,10 +1025,10 @@ boost::system::error_code context::use_tmp_dh_file(
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code context::do_use_tmp_dh(
+BOOST_ASIO_SYNC_OP_VOID context::do_use_tmp_dh(
     BIO* bio, boost::system::error_code& ec)
 {
   ::ERR_clear_error();
@@ -1056,17 +1039,17 @@ boost::system::error_code context::do_use_tmp_dh(
     if (::SSL_CTX_set_tmp_dh(handle_, dh.p) == 1)
     {
       ec = boost::system::error_code();
-      return ec;
+      BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
     }
   }
 
   ec = boost::system::error_code(
       static_cast<int>(::ERR_get_error()),
       boost::asio::error::get_ssl_category());
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
-boost::system::error_code context::do_set_verify_callback(
+BOOST_ASIO_SYNC_OP_VOID context::do_set_verify_callback(
     detail::verify_callback_base* callback, boost::system::error_code& ec)
 {
   if (SSL_CTX_get_app_data(handle_))
@@ -1082,7 +1065,7 @@ boost::system::error_code context::do_set_verify_callback(
       &context::verify_callback_function);
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 int context::verify_callback_function(int preverified, X509_STORE_CTX* ctx)
@@ -1111,7 +1094,7 @@ int context::verify_callback_function(int preverified, X509_STORE_CTX* ctx)
   return 0;
 }
 
-boost::system::error_code context::do_set_password_callback(
+BOOST_ASIO_SYNC_OP_VOID context::do_set_password_callback(
     detail::password_callback_base* callback, boost::system::error_code& ec)
 {
 #if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
@@ -1129,7 +1112,7 @@ boost::system::error_code context::do_set_password_callback(
   SSL_CTX_set_default_passwd_cb(handle_, &context::password_callback_function);
 
   ec = boost::system::error_code();
-  return ec;
+  BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
 }
 
 int context::password_callback_function(
@@ -1162,12 +1145,10 @@ int context::password_callback_function(
 BIO* context::make_buffer_bio(const const_buffer& b)
 {
   return ::BIO_new_mem_buf(
-      const_cast<void*>(buffer_cast<const void*>(b)),
-      static_cast<int>(buffer_size(b)));
+      const_cast<void*>(b.data()),
+      static_cast<int>(b.size()));
 }
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace ssl
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/ssl/impl/rfc2818_verification.ipp b/include/boost/asio/ssl/impl/rfc2818_verification.ipp
index 7f22806735..d759ce567c 100644
--- a/include/boost/asio/ssl/impl/rfc2818_verification.ipp
+++ b/include/boost/asio/ssl/impl/rfc2818_verification.ipp
@@ -17,13 +17,11 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <cctype>
-# include <cstring>
-# include <boost/asio/ip/address.hpp>
-# include <boost/asio/ssl/rfc2818_verification.hpp>
-# include <boost/asio/ssl/detail/openssl_types.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <cctype>
+#include <cstring>
+#include <boost/asio/ip/address.hpp>
+#include <boost/asio/ssl/rfc2818_verification.hpp>
+#include <boost/asio/ssl/detail/openssl_types.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -31,8 +29,6 @@ namespace boost {
 namespace asio {
 namespace ssl {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 bool rfc2818_verification::operator()(
     bool preverified, verify_context& ctx) const
 {
@@ -50,7 +46,7 @@ bool rfc2818_verification::operator()(
   // Try converting the host name to an address. If it is an address then we
   // need to look for an IP address in the certificate rather than a host name.
   boost::system::error_code ec;
-  ip::address address = ip::address::from_string(host_, ec);
+  ip::address address = ip::make_address(host_, ec);
   bool is_address = !ec;
 
   X509* cert = X509_STORE_CTX_get_current_cert(ctx.native_handle());
@@ -157,8 +153,6 @@ bool rfc2818_verification::match_pattern(const char* pattern,
   return p == p_end && !*h;
 }
 
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace ssl
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/ssl/old/basic_context.hpp b/include/boost/asio/ssl/old/basic_context.hpp
deleted file mode 100644
index d8703b21ae..0000000000
--- a/include/boost/asio/ssl/old/basic_context.hpp
+++ /dev/null
@@ -1,436 +0,0 @@
-//
-// ssl/old/basic_context.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2005 Voipster / Indrek dot Juhani at voipster dot com
-// Copyright (c) 2005-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_OLD_BASIC_CONTEXT_HPP
-#define BOOST_ASIO_SSL_OLD_BASIC_CONTEXT_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <string>
-#include <boost/noncopyable.hpp>
-#include <boost/asio/detail/throw_error.hpp>
-#include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ssl/context_base.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-namespace old {
-
-/// SSL context.
-template <typename Service>
-class basic_context
-  : public context_base,
-    private boost::noncopyable
-{
-public:
-  /// The type of the service that will be used to provide context operations.
-  typedef Service service_type;
-
-  /// The native implementation type of the SSL context.
-  typedef typename service_type::impl_type impl_type;
-
-  /// Constructor.
-  basic_context(boost::asio::io_service& io_service, method m)
-    : service_(boost::asio::use_service<Service>(io_service)),
-      impl_(service_.null())
-  {
-    service_.create(impl_, m);
-  }
-
-  /// Destructor.
-  ~basic_context()
-  {
-    service_.destroy(impl_);
-  }
-
-  /// Get the underlying implementation in the native type.
-  /**
-   * This function may be used to obtain the underlying implementation of the
-   * context. This is intended to allow access to context functionality that is
-   * not otherwise provided.
-   */
-  impl_type impl()
-  {
-    return impl_;
-  }
-
-  /// Set options on the context.
-  /**
-   * This function may be used to configure the SSL options used by the context.
-   *
-   * @param o A bitmask of options. The available option values are defined in
-   * the context_base class. The options are bitwise-ored with any existing
-   * value for the options.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void set_options(options o)
-  {
-    boost::system::error_code ec;
-    service_.set_options(impl_, o, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Set options on the context.
-  /**
-   * This function may be used to configure the SSL options used by the context.
-   *
-   * @param o A bitmask of options. The available option values are defined in
-   * the context_base class. The options are bitwise-ored with any existing
-   * value for the options.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code set_options(options o,
-      boost::system::error_code& ec)
-  {
-    return service_.set_options(impl_, o, ec);
-  }
-
-  /// Set the peer verification mode.
-  /**
-   * This function may be used to configure the peer verification mode used by
-   * the context.
-   *
-   * @param v A bitmask of peer verification modes. The available verify_mode
-   * values are defined in the context_base class.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void set_verify_mode(verify_mode v)
-  {
-    boost::system::error_code ec;
-    service_.set_verify_mode(impl_, v, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Set the peer verification mode.
-  /**
-   * This function may be used to configure the peer verification mode used by
-   * the context.
-   *
-   * @param v A bitmask of peer verification modes. The available verify_mode
-   * values are defined in the context_base class.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code set_verify_mode(verify_mode v,
-      boost::system::error_code& ec)
-  {
-    return service_.set_verify_mode(impl_, v, ec);
-  }
-
-  /// Load a certification authority file for performing verification.
-  /**
-   * This function is used to load one or more trusted certification authorities
-   * from a file.
-   *
-   * @param filename The name of a file containing certification authority
-   * certificates in PEM format.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void load_verify_file(const std::string& filename)
-  {
-    boost::system::error_code ec;
-    service_.load_verify_file(impl_, filename, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Load a certification authority file for performing verification.
-  /**
-   * This function is used to load the certificates for one or more trusted
-   * certification authorities from a file.
-   *
-   * @param filename The name of a file containing certification authority
-   * certificates in PEM format.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code load_verify_file(const std::string& filename,
-      boost::system::error_code& ec)
-  {
-    return service_.load_verify_file(impl_, filename, ec);
-  }
-
-  /// Add a directory containing certificate authority files to be used for
-  /// performing verification.
-  /**
-   * This function is used to specify the name of a directory containing
-   * certification authority certificates. Each file in the directory must
-   * contain a single certificate. The files must be named using the subject
-   * name's hash and an extension of ".0".
-   *
-   * @param path The name of a directory containing the certificates.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void add_verify_path(const std::string& path)
-  {
-    boost::system::error_code ec;
-    service_.add_verify_path(impl_, path, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Add a directory containing certificate authority files to be used for
-  /// performing verification.
-  /**
-   * This function is used to specify the name of a directory containing
-   * certification authority certificates. Each file in the directory must
-   * contain a single certificate. The files must be named using the subject
-   * name's hash and an extension of ".0".
-   *
-   * @param path The name of a directory containing the certificates.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code add_verify_path(const std::string& path,
-      boost::system::error_code& ec)
-  {
-    return service_.add_verify_path(impl_, path, ec);
-  }
-
-  /// Use a certificate from a file.
-  /**
-   * This function is used to load a certificate into the context from a file.
-   *
-   * @param filename The name of the file containing the certificate.
-   *
-   * @param format The file format (ASN.1 or PEM).
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void use_certificate_file(const std::string& filename, file_format format)
-  {
-    boost::system::error_code ec;
-    service_.use_certificate_file(impl_, filename, format, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Use a certificate from a file.
-  /**
-   * This function is used to load a certificate into the context from a file.
-   *
-   * @param filename The name of the file containing the certificate.
-   *
-   * @param format The file format (ASN.1 or PEM).
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code use_certificate_file(const std::string& filename,
-      file_format format, boost::system::error_code& ec)
-  {
-    return service_.use_certificate_file(impl_, filename, format, ec);
-  }
-
-  /// Use a certificate chain from a file.
-  /**
-   * This function is used to load a certificate chain into the context from a
-   * file.
-   *
-   * @param filename The name of the file containing the certificate. The file
-   * must use the PEM format.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void use_certificate_chain_file(const std::string& filename)
-  {
-    boost::system::error_code ec;
-    service_.use_certificate_chain_file(impl_, filename, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Use a certificate chain from a file.
-  /**
-   * This function is used to load a certificate chain into the context from a
-   * file.
-   *
-   * @param filename The name of the file containing the certificate. The file
-   * must use the PEM format.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code use_certificate_chain_file(
-      const std::string& filename, boost::system::error_code& ec)
-  {
-    return service_.use_certificate_chain_file(impl_, filename, ec);
-  }
-
-  /// Use a private key from a file.
-  /**
-   * This function is used to load a private key into the context from a file.
-   *
-   * @param filename The name of the file containing the private key.
-   *
-   * @param format The file format (ASN.1 or PEM).
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void use_private_key_file(const std::string& filename, file_format format)
-  {
-    boost::system::error_code ec;
-    service_.use_private_key_file(impl_, filename, format, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Use a private key from a file.
-  /**
-   * This function is used to load a private key into the context from a file.
-   *
-   * @param filename The name of the file containing the private key.
-   *
-   * @param format The file format (ASN.1 or PEM).
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code use_private_key_file(const std::string& filename,
-      file_format format, boost::system::error_code& ec)
-  {
-    return service_.use_private_key_file(impl_, filename, format, ec);
-  }
-
-  /// Use an RSA private key from a file.
-  /**
-   * This function is used to load an RSA private key into the context from a
-   * file.
-   *
-   * @param filename The name of the file containing the RSA private key.
-   *
-   * @param format The file format (ASN.1 or PEM).
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void use_rsa_private_key_file(const std::string& filename, file_format format)
-  {
-    boost::system::error_code ec;
-    service_.use_rsa_private_key_file(impl_, filename, format, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Use an RSA private key from a file.
-  /**
-   * This function is used to load an RSA private key into the context from a
-   * file.
-   *
-   * @param filename The name of the file containing the RSA private key.
-   *
-   * @param format The file format (ASN.1 or PEM).
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code use_rsa_private_key_file(
-      const std::string& filename, file_format format,
-      boost::system::error_code& ec)
-  {
-    return service_.use_rsa_private_key_file(impl_, filename, format, ec);
-  }
-
-  /// Use the specified file to obtain the temporary Diffie-Hellman parameters.
-  /**
-   * This function is used to load Diffie-Hellman parameters into the context
-   * from a file.
-   *
-   * @param filename The name of the file containing the Diffie-Hellman
-   * parameters. The file must use the PEM format.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void use_tmp_dh_file(const std::string& filename)
-  {
-    boost::system::error_code ec;
-    service_.use_tmp_dh_file(impl_, filename, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Use the specified file to obtain the temporary Diffie-Hellman parameters.
-  /**
-   * This function is used to load Diffie-Hellman parameters into the context
-   * from a file.
-   *
-   * @param filename The name of the file containing the Diffie-Hellman
-   * parameters. The file must use the PEM format.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code use_tmp_dh_file(const std::string& filename,
-      boost::system::error_code& ec)
-  {
-    return service_.use_tmp_dh_file(impl_, filename, ec);
-  }
-
-  /// Set the password callback.
-  /**
-   * This function is used to specify a callback function to obtain password
-   * information about an encrypted key in PEM format.
-   *
-   * @param callback The function object to be used for obtaining the password.
-   * The function signature of the handler must be:
-   * @code std::string password_callback(
-   *   std::size_t max_length,  // The maximum size for a password.
-   *   password_purpose purpose // Whether password is for reading or writing.
-   * ); @endcode
-   * The return value of the callback is a string containing the password.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  template <typename PasswordCallback>
-  void set_password_callback(PasswordCallback callback)
-  {
-    boost::system::error_code ec;
-    service_.set_password_callback(impl_, callback, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Set the password callback.
-  /**
-   * This function is used to specify a callback function to obtain password
-   * information about an encrypted key in PEM format.
-   *
-   * @param callback The function object to be used for obtaining the password.
-   * The function signature of the handler must be:
-   * @code std::string password_callback(
-   *   std::size_t max_length,  // The maximum size for a password.
-   *   password_purpose purpose // Whether password is for reading or writing.
-   * ); @endcode
-   * The return value of the callback is a string containing the password.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  template <typename PasswordCallback>
-  boost::system::error_code set_password_callback(PasswordCallback callback,
-      boost::system::error_code& ec)
-  {
-    return service_.set_password_callback(impl_, callback, ec);
-  }
-
-private:
-  /// The backend service implementation.
-  service_type& service_;
-
-  /// The underlying native implementation.
-  impl_type impl_;
-};
-
-} // namespace old
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_OLD_BASIC_CONTEXT_HPP
diff --git a/include/boost/asio/ssl/old/context_service.hpp b/include/boost/asio/ssl/old/context_service.hpp
deleted file mode 100644
index 1d9fbc0751..0000000000
--- a/include/boost/asio/ssl/old/context_service.hpp
+++ /dev/null
@@ -1,176 +0,0 @@
-//
-// ssl/old/context_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2005 Voipster / Indrek dot Juhani at voipster dot com
-// Copyright (c) 2005-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_OLD_CONTEXT_SERVICE_HPP
-#define BOOST_ASIO_SSL_OLD_CONTEXT_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <string>
-#include <boost/noncopyable.hpp>
-#include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ssl/context_base.hpp>
-#include <boost/asio/ssl/old/detail/openssl_context_service.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-namespace old {
-
-/// Default service implementation for a context.
-class context_service
-#if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
-#else
-  : public boost::asio::detail::service_base<context_service>
-#endif
-{
-private:
-  // The type of the platform-specific implementation.
-  typedef old::detail::openssl_context_service service_impl_type;
-
-public:
-#if defined(GENERATING_DOCUMENTATION)
-  /// The unique service identifier.
-  static boost::asio::io_service::id id;
-#endif
-
-  /// The type of the context.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined impl_type;
-#else
-  typedef service_impl_type::impl_type impl_type;
-#endif
-
-  /// Constructor.
-  explicit context_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<context_service>(io_service),
-      service_impl_(boost::asio::use_service<service_impl_type>(io_service))
-  {
-  }
-
-  /// Return a null context implementation.
-  impl_type null() const
-  {
-    return service_impl_.null();
-  }
-
-  /// Create a new context implementation.
-  void create(impl_type& impl, context_base::method m)
-  {
-    service_impl_.create(impl, m);
-  }
-
-  /// Destroy a context implementation.
-  void destroy(impl_type& impl)
-  {
-    service_impl_.destroy(impl);
-  }
-
-  /// Set options on the context.
-  boost::system::error_code set_options(impl_type& impl,
-      context_base::options o, boost::system::error_code& ec)
-  {
-    return service_impl_.set_options(impl, o, ec);
-  }
-
-  /// Set peer verification mode.
-  boost::system::error_code set_verify_mode(impl_type& impl,
-      context_base::verify_mode v, boost::system::error_code& ec)
-  {
-    return service_impl_.set_verify_mode(impl, v, ec);
-  }
-
-  /// Load a certification authority file for performing verification.
-  boost::system::error_code load_verify_file(impl_type& impl,
-      const std::string& filename, boost::system::error_code& ec)
-  {
-    return service_impl_.load_verify_file(impl, filename, ec);
-  }
-
-  /// Add a directory containing certification authority files to be used for
-  /// performing verification.
-  boost::system::error_code add_verify_path(impl_type& impl,
-      const std::string& path, boost::system::error_code& ec)
-  {
-    return service_impl_.add_verify_path(impl, path, ec);
-  }
-
-  /// Use a certificate from a file.
-  boost::system::error_code use_certificate_file(impl_type& impl,
-      const std::string& filename, context_base::file_format format,
-      boost::system::error_code& ec)
-  {
-    return service_impl_.use_certificate_file(impl, filename, format, ec);
-  }
-
-  /// Use a certificate chain from a file.
-  boost::system::error_code use_certificate_chain_file(impl_type& impl,
-      const std::string& filename, boost::system::error_code& ec)
-  {
-    return service_impl_.use_certificate_chain_file(impl, filename, ec);
-  }
-
-  /// Use a private key from a file.
-  boost::system::error_code use_private_key_file(impl_type& impl,
-      const std::string& filename, context_base::file_format format,
-      boost::system::error_code& ec)
-  {
-    return service_impl_.use_private_key_file(impl, filename, format, ec);
-  }
-
-  /// Use an RSA private key from a file.
-  boost::system::error_code use_rsa_private_key_file(impl_type& impl,
-      const std::string& filename, context_base::file_format format,
-      boost::system::error_code& ec)
-  {
-    return service_impl_.use_rsa_private_key_file(impl, filename, format, ec);
-  }
-
-  /// Use the specified file to obtain the temporary Diffie-Hellman parameters.
-  boost::system::error_code use_tmp_dh_file(impl_type& impl,
-      const std::string& filename, boost::system::error_code& ec)
-  {
-    return service_impl_.use_tmp_dh_file(impl, filename, ec);
-  }
-
-  /// Set the password callback.
-  template <typename PasswordCallback>
-  boost::system::error_code set_password_callback(impl_type& impl,
-      PasswordCallback callback, boost::system::error_code& ec)
-  {
-    return service_impl_.set_password_callback(impl, callback, ec);
-  }
-
-private:
-  // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
-  {
-  }
-
-  // The service that provides the platform-specific implementation.
-  service_impl_type& service_impl_;
-};
-
-} // namespace old
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_OLD_CONTEXT_SERVICE_HPP
diff --git a/include/boost/asio/ssl/old/detail/openssl_context_service.hpp b/include/boost/asio/ssl/old/detail/openssl_context_service.hpp
deleted file mode 100644
index dd54c3297b..0000000000
--- a/include/boost/asio/ssl/old/detail/openssl_context_service.hpp
+++ /dev/null
@@ -1,396 +0,0 @@
-//
-// ssl/old/detail/openssl_context_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2005 Voipster / Indrek dot Juhani at voipster dot com
-// Copyright (c) 2005-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_CONTEXT_SERVICE_HPP
-#define BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_CONTEXT_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <cstring>
-#include <string>
-#include <boost/function.hpp>
-#include <boost/asio/detail/throw_error.hpp>
-#include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ssl/context_base.hpp>
-#include <boost/asio/ssl/detail/openssl_init.hpp>
-#include <boost/asio/ssl/detail/openssl_types.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-namespace old {
-namespace detail {
-
-class openssl_context_service
-  : public boost::asio::detail::service_base<openssl_context_service>
-{
-public:
-  // The native type of the context.
-  typedef ::SSL_CTX* impl_type;
-
-  // The type for the password callback function object.
-  typedef boost::function<std::string(std::size_t,
-      context_base::password_purpose)> password_callback_type;
-
-  // Constructor.
-  openssl_context_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<openssl_context_service>(io_service)
-  {
-  }
-
-  // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
-  {
-  }
-
-  // Return a null context implementation.
-  static impl_type null()
-  {
-    return 0;
-  }
-
-  // Create a new context implementation.
-  void create(impl_type& impl, context_base::method m)
-  {
-    switch (m)
-    {
-#if defined(OPENSSL_NO_SSL2)
-    case context_base::sslv2:
-    case context_base::sslv2_client:
-    case context_base::sslv2_server:
-      boost::asio::detail::throw_error(boost::asio::error::invalid_argument);
-      break;
-#else // defined(OPENSSL_NO_SSL2)
-    case context_base::sslv2:
-      impl = ::SSL_CTX_new(::SSLv2_method());
-      break;
-    case context_base::sslv2_client:
-      impl = ::SSL_CTX_new(::SSLv2_client_method());
-      break;
-    case context_base::sslv2_server:
-      impl = ::SSL_CTX_new(::SSLv2_server_method());
-      break;
-#endif // defined(OPENSSL_NO_SSL2)
-#if defined(OPENSSL_NO_SSL3)
-    case context_base::sslv3:
-    case context_base::sslv3_client:
-    case context_base::sslv3_server:
-      boost::asio::detail::throw_error(boost::asio::error::invalid_argument);
-      break;
-#else // defined(OPENSSL_NO_SSL3)
-    case context_base::sslv3:
-      impl = ::SSL_CTX_new(::SSLv3_method());
-      break;
-    case context_base::sslv3_client:
-      impl = ::SSL_CTX_new(::SSLv3_client_method());
-      break;
-    case context_base::sslv3_server:
-      impl = ::SSL_CTX_new(::SSLv3_server_method());
-      break;
-#endif // defined(OPENSSL_NO_SSL3)
-    case context_base::tlsv1:
-      impl = ::SSL_CTX_new(::TLSv1_method());
-      break;
-    case context_base::tlsv1_client:
-      impl = ::SSL_CTX_new(::TLSv1_client_method());
-      break;
-    case context_base::tlsv1_server:
-      impl = ::SSL_CTX_new(::TLSv1_server_method());
-      break;
-    case context_base::sslv23:
-      impl = ::SSL_CTX_new(::SSLv23_method());
-      break;
-    case context_base::sslv23_client:
-      impl = ::SSL_CTX_new(::SSLv23_client_method());
-      break;
-    case context_base::sslv23_server:
-      impl = ::SSL_CTX_new(::SSLv23_server_method());
-      break;
-    default:
-      impl = ::SSL_CTX_new(0);
-      break;
-    }
-  }
-
-  // Destroy a context implementation.
-  void destroy(impl_type& impl)
-  {
-    if (impl != null())
-    {
-      if (impl->default_passwd_callback_userdata)
-      {
-        password_callback_type* callback =
-          static_cast<password_callback_type*>(
-              impl->default_passwd_callback_userdata);
-        delete callback;
-        impl->default_passwd_callback_userdata = 0;
-      }
-
-      ::SSL_CTX_free(impl);
-      impl = null();
-    }
-  }
-
-  // Set options on the context.
-  boost::system::error_code set_options(impl_type& impl,
-      context_base::options o, boost::system::error_code& ec)
-  {
-    ::SSL_CTX_set_options(impl, o);
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Set peer verification mode.
-  boost::system::error_code set_verify_mode(impl_type& impl,
-      context_base::verify_mode v, boost::system::error_code& ec)
-  {
-    ::SSL_CTX_set_verify(impl, v, 0);
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Load a certification authority file for performing verification.
-  boost::system::error_code load_verify_file(impl_type& impl,
-      const std::string& filename, boost::system::error_code& ec)
-  {
-    if (::SSL_CTX_load_verify_locations(impl, filename.c_str(), 0) != 1)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Add a directory containing certification authority files to be used for
-  // performing verification.
-  boost::system::error_code add_verify_path(impl_type& impl,
-      const std::string& path, boost::system::error_code& ec)
-  {
-    if (::SSL_CTX_load_verify_locations(impl, 0, path.c_str()) != 1)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Use a certificate from a file.
-  boost::system::error_code use_certificate_file(impl_type& impl,
-      const std::string& filename, context_base::file_format format,
-      boost::system::error_code& ec)
-  {
-    int file_type;
-    switch (format)
-    {
-    case context_base::asn1:
-      file_type = SSL_FILETYPE_ASN1;
-      break;
-    case context_base::pem:
-      file_type = SSL_FILETYPE_PEM;
-      break;
-    default:
-      {
-        ec = boost::asio::error::invalid_argument;
-        return ec;
-      }
-    }
-
-    if (::SSL_CTX_use_certificate_file(impl, filename.c_str(), file_type) != 1)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Use a certificate chain from a file.
-  boost::system::error_code use_certificate_chain_file(impl_type& impl,
-      const std::string& filename, boost::system::error_code& ec)
-  {
-    if (::SSL_CTX_use_certificate_chain_file(impl, filename.c_str()) != 1)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Use a private key from a file.
-  boost::system::error_code use_private_key_file(impl_type& impl,
-      const std::string& filename, context_base::file_format format,
-      boost::system::error_code& ec)
-  {
-    int file_type;
-    switch (format)
-    {
-    case context_base::asn1:
-      file_type = SSL_FILETYPE_ASN1;
-      break;
-    case context_base::pem:
-      file_type = SSL_FILETYPE_PEM;
-      break;
-    default:
-      {
-        ec = boost::asio::error::invalid_argument;
-        return ec;
-      }
-    }
-
-    if (::SSL_CTX_use_PrivateKey_file(impl, filename.c_str(), file_type) != 1)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Use an RSA private key from a file.
-  boost::system::error_code use_rsa_private_key_file(impl_type& impl,
-      const std::string& filename, context_base::file_format format,
-      boost::system::error_code& ec)
-  {
-    int file_type;
-    switch (format)
-    {
-    case context_base::asn1:
-      file_type = SSL_FILETYPE_ASN1;
-      break;
-    case context_base::pem:
-      file_type = SSL_FILETYPE_PEM;
-      break;
-    default:
-      {
-        ec = boost::asio::error::invalid_argument;
-        return ec;
-      }
-    }
-
-    if (::SSL_CTX_use_RSAPrivateKey_file(
-          impl, filename.c_str(), file_type) != 1)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Use the specified file to obtain the temporary Diffie-Hellman parameters.
-  boost::system::error_code use_tmp_dh_file(impl_type& impl,
-      const std::string& filename, boost::system::error_code& ec)
-  {
-    ::BIO* bio = ::BIO_new_file(filename.c_str(), "r");
-    if (!bio)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ::DH* dh = ::PEM_read_bio_DHparams(bio, 0, 0, 0);
-    if (!dh)
-    {
-      ::BIO_free(bio);
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ::BIO_free(bio);
-    int result = ::SSL_CTX_set_tmp_dh(impl, dh);
-    ::DH_free(dh);
-    if (result != 1)
-    {
-      ec = boost::asio::error::invalid_argument;
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  static int password_callback(char* buf, int size, int purpose, void* data)
-  {
-    using namespace std; // For strncat and strlen.
-
-    if (data)
-    {
-      password_callback_type* callback =
-        static_cast<password_callback_type*>(data);
-      std::string passwd = (*callback)(static_cast<std::size_t>(size),
-          purpose ? context_base::for_writing : context_base::for_reading);
-      *buf = '\0';
-      strncat(buf, passwd.c_str(), size);
-      return strlen(buf);
-    }
-
-    return 0;
-  }
-
-  // Set the password callback.
-  template <typename Password_Callback>
-  boost::system::error_code set_password_callback(impl_type& impl,
-      Password_Callback callback, boost::system::error_code& ec)
-  {
-    // Allocate callback function object if not already present.
-    if (impl->default_passwd_callback_userdata)
-    {
-      password_callback_type* callback_function =
-        static_cast<password_callback_type*>(
-            impl->default_passwd_callback_userdata);
-      *callback_function = callback;
-    }
-    else
-    {
-      password_callback_type* callback_function =
-        new password_callback_type(callback);
-      impl->default_passwd_callback_userdata = callback_function;
-    }
-
-    // Set the password callback.
-    SSL_CTX_set_default_passwd_cb(impl,
-        &openssl_context_service::password_callback);
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-private:
-  // Ensure openssl is initialised.
-  boost::asio::ssl::detail::openssl_init<> init_;
-};
-
-} // namespace detail
-} // namespace old
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_CONTEXT_SERVICE_HPP
diff --git a/include/boost/asio/ssl/old/detail/openssl_operation.hpp b/include/boost/asio/ssl/old/detail/openssl_operation.hpp
deleted file mode 100644
index 6835f5ff6a..0000000000
--- a/include/boost/asio/ssl/old/detail/openssl_operation.hpp
+++ /dev/null
@@ -1,526 +0,0 @@
-//
-// ssl/old/detail/openssl_operation.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2005 Voipster / Indrek dot Juhani at voipster dot com
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_OPERATION_HPP
-#define BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_OPERATION_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <boost/function.hpp>
-#include <boost/bind.hpp>
-#include <boost/asio/buffer.hpp>
-#include <boost/asio/detail/assert.hpp>
-#include <boost/asio/detail/socket_ops.hpp>
-#include <boost/asio/placeholders.hpp>
-#include <boost/asio/ssl/detail/openssl_types.hpp>
-#include <boost/asio/ssl/error.hpp>
-#include <boost/asio/strand.hpp>
-#include <boost/system/system_error.hpp>
-#include <boost/asio/write.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-namespace old {
-namespace detail {
-
-typedef boost::function<int (::SSL*)> ssl_primitive_func; 
-typedef boost::function<void (const boost::system::error_code&, int)>
-  user_handler_func;
-
-// Network send_/recv buffer implementation
-//
-//
-class net_buffer
-{
-  static const int  NET_BUF_SIZE = 16*1024 + 256; // SSL record size + spare
-
-  unsigned char buf_[NET_BUF_SIZE];
-  unsigned char* data_start_;
-  unsigned char* data_end_;
-
-public:
-  net_buffer()
-  {
-    data_start_ = data_end_ = buf_;
-  }
-  unsigned char* get_unused_start() { return data_end_; }
-  unsigned char* get_data_start() { return data_start_; }
-  size_t get_unused_len() { return (NET_BUF_SIZE - (data_end_ - buf_)); }    
-  size_t get_data_len() { return (data_end_ - data_start_); }    
-  void data_added(size_t count)
-  { 
-    data_end_ += count; 
-    data_end_ = data_end_ > (buf_ + NET_BUF_SIZE)? 
-      (buf_ + NET_BUF_SIZE):
-      data_end_; 
-  }
-  void data_removed(size_t count) 
-  { 
-    data_start_ += count; 
-    if (data_start_ >= data_end_) reset(); 
-  }
-  void reset() { data_start_ = buf_; data_end_ = buf_; }               
-  bool has_data() { return (data_start_ < data_end_); }
-}; // class net_buffer
-
-//
-// Operation class
-//
-//
-template <typename Stream>
-class openssl_operation
-{
-public:
-
-  // Constructor for asynchronous operations
-  openssl_operation(ssl_primitive_func primitive,
-                    Stream& socket,
-                    net_buffer& recv_buf,
-                    SSL* session,
-                    BIO* ssl_bio,
-                    user_handler_func  handler,
-                    boost::asio::io_service::strand& strand
-                    )
-    : primitive_(primitive)
-    , user_handler_(handler)
-    , strand_(&strand)
-    , recv_buf_(recv_buf)
-    , socket_(socket)
-    , ssl_bio_(ssl_bio)
-    , session_(session)
-  {
-    write_ = boost::bind(
-      &openssl_operation::do_async_write, 
-      this, boost::arg<1>(), boost::arg<2>()
-    );
-    read_ = boost::bind(
-      &openssl_operation::do_async_read, 
-      this
-    );
-    handler_= boost::bind(
-      &openssl_operation::async_user_handler, 
-      this, boost::arg<1>(), boost::arg<2>()
-    );
-  }
-
-  // Constructor for synchronous operations
-  openssl_operation(ssl_primitive_func primitive,
-                    Stream& socket,
-                    net_buffer& recv_buf,
-                    SSL* session,
-                    BIO* ssl_bio)
-    : primitive_(primitive)
-    , strand_(0)
-    , recv_buf_(recv_buf)
-    , socket_(socket)
-    , ssl_bio_(ssl_bio)
-    , session_(session)
-  {      
-    write_ = boost::bind(
-      &openssl_operation::do_sync_write, 
-      this, boost::arg<1>(), boost::arg<2>()
-    );
-    read_ = boost::bind(
-      &openssl_operation::do_sync_read, 
-      this
-    );
-    handler_ = boost::bind(
-      &openssl_operation::sync_user_handler, 
-      this, boost::arg<1>(), boost::arg<2>()
-      );
-  }
-
-  // Start operation
-  // In case of asynchronous it returns 0, in sync mode returns success code
-  // or throws an error...
-  int start()
-  {
-    int rc = primitive_( session_ );
-
-    bool is_operation_done = (rc > 0);  
-                // For connect/accept/shutdown, the operation
-                // is done, when return code is 1
-                // for write, it is done, when is retcode > 0
-                // for read, it is done when retcode > 0
-
-    int error_code =  !is_operation_done ?
-          ::SSL_get_error( session_, rc ) :
-          0;        
-    int sys_error_code = ERR_get_error();
-
-    if (error_code == SSL_ERROR_SSL)
-      return handler_(boost::system::error_code(
-            sys_error_code, boost::asio::error::get_ssl_category()), rc);
-
-    bool is_read_needed = (error_code == SSL_ERROR_WANT_READ);
-    bool is_write_needed = (error_code == SSL_ERROR_WANT_WRITE ||
-                              ::BIO_ctrl_pending( ssl_bio_ ));
-    bool is_shut_down_received = 
-      ((::SSL_get_shutdown( session_ ) & SSL_RECEIVED_SHUTDOWN) == 
-          SSL_RECEIVED_SHUTDOWN);
-    bool is_shut_down_sent = 
-      ((::SSL_get_shutdown( session_ ) & SSL_SENT_SHUTDOWN) ==
-            SSL_SENT_SHUTDOWN);
-
-    if (is_shut_down_sent && is_shut_down_received
-        && is_operation_done && !is_write_needed)
-      // SSL connection is shut down cleanly
-      return handler_(boost::system::error_code(), 1);
-
-    if (is_shut_down_received && !is_operation_done)
-      // Shutdown has been requested, while we were reading or writing...
-      // abort our action...
-      return handler_(boost::asio::error::shut_down, 0);
-
-    if (!is_operation_done && !is_read_needed && !is_write_needed 
-      && !is_shut_down_sent)
-    {
-      // The operation has failed... It is not completed and does 
-      // not want network communication nor does want to send shutdown out...
-      if (error_code == SSL_ERROR_SYSCALL)
-      {
-        return handler_(boost::system::error_code(
-              sys_error_code, boost::asio::error::system_category), rc); 
-      }
-      else
-      {
-        return handler_(boost::system::error_code(
-              sys_error_code, boost::asio::error::get_ssl_category()), rc); 
-      }
-    }
-
-    if (!is_operation_done && !is_write_needed)
-    {
-      // We may have left over data that we can pass to SSL immediately
-      if (recv_buf_.get_data_len() > 0)
-      {
-        // Pass the buffered data to SSL
-        int written = ::BIO_write
-        ( 
-          ssl_bio_, 
-          recv_buf_.get_data_start(), 
-          recv_buf_.get_data_len() 
-        );
-
-        if (written > 0)
-        {
-          recv_buf_.data_removed(written);
-        }
-        else if (written < 0)
-        {
-          if (!BIO_should_retry(ssl_bio_))
-          {
-            // Some serios error with BIO....
-            return handler_(boost::asio::error::no_recovery, 0);
-          }
-        }
-
-        return start();
-      }
-      else if (is_read_needed || (is_shut_down_sent && !is_shut_down_received))
-      {
-        return read_();
-      }
-    }
-
-    // Continue with operation, flush any SSL data out to network...
-    return write_(is_operation_done, rc); 
-  }
-
-// Private implementation
-private:
-  typedef boost::function<int (const boost::system::error_code&, int)>
-    int_handler_func;
-  typedef boost::function<int (bool, int)> write_func;
-  typedef boost::function<int ()> read_func;
-
-  ssl_primitive_func  primitive_;
-  user_handler_func  user_handler_;
-  boost::asio::io_service::strand* strand_;
-  write_func  write_;
-  read_func  read_;
-  int_handler_func handler_;
-    
-  net_buffer send_buf_; // buffers for network IO
-
-  // The recv buffer is owned by the stream, not the operation, since there can
-  // be left over bytes after passing the data up to the application, and these
-  // bytes need to be kept around for the next read operation issued by the
-  // application.
-  net_buffer& recv_buf_;
-
-  Stream& socket_;
-  BIO*    ssl_bio_;
-  SSL*    session_;
-
-  //
-  int sync_user_handler(const boost::system::error_code& error, int rc)
-  {
-    if (!error)
-      return rc;
-
-    throw boost::system::system_error(error);
-  }
-    
-  int async_user_handler(boost::system::error_code error, int rc)
-  {
-    if (rc < 0)
-    {
-      if (!error)
-        error = boost::asio::error::no_recovery;
-      rc = 0;
-    }
-
-    user_handler_(error, rc);
-    return 0;
-  }
-
-  // Writes bytes asynchronously from SSL to NET
-  int  do_async_write(bool is_operation_done, int rc) 
-  {
-    int len = ::BIO_ctrl_pending( ssl_bio_ );
-    if ( len )
-    { 
-      // There is something to write into net, do it...
-      len = (int)send_buf_.get_unused_len() > len? 
-        len: 
-        send_buf_.get_unused_len();
-        
-      if (len == 0)
-      {
-        // In case our send buffer is full, we have just to wait until 
-        // previous send to complete...
-        return 0;
-      }
-
-      // Read outgoing data from bio
-      len = ::BIO_read( ssl_bio_, send_buf_.get_unused_start(), len); 
-         
-      if (len > 0)
-      {
-        unsigned char *data_start = send_buf_.get_unused_start();
-        send_buf_.data_added(len);
- 
-        BOOST_ASIO_ASSERT(strand_);
-        boost::asio::async_write
-        ( 
-          socket_, 
-          boost::asio::buffer(data_start, len),
-          strand_->wrap
-          (
-            boost::bind
-            (
-              &openssl_operation::async_write_handler, 
-              this, 
-              is_operation_done,
-              rc, 
-              boost::asio::placeholders::error, 
-              boost::asio::placeholders::bytes_transferred
-            )
-          )
-        );
-                  
-        return 0;
-      }
-      else if (!BIO_should_retry(ssl_bio_))
-      {
-        // Seems like fatal error
-        // reading from SSL BIO has failed...
-        handler_(boost::asio::error::no_recovery, 0);
-        return 0;
-      }
-    }
-    
-    if (is_operation_done)
-    {
-      // Finish the operation, with success
-      handler_(boost::system::error_code(), rc);
-      return 0;
-    }
-    
-    // OPeration is not done and writing to net has been made...
-    // start operation again
-    start();
-          
-    return 0;
-  }
-
-  void async_write_handler(bool is_operation_done, int rc, 
-    const boost::system::error_code& error, size_t bytes_sent)
-  {
-    if (!error)
-    {
-      // Remove data from send buffer
-      send_buf_.data_removed(bytes_sent);
-
-      if (is_operation_done)
-        handler_(boost::system::error_code(), rc);
-      else
-        // Since the operation was not completed, try it again...
-        start();
-    }
-    else 
-      handler_(error, rc);
-  }
-
-  int do_async_read()
-  {
-    // Wait for new data
-    BOOST_ASIO_ASSERT(strand_);
-    socket_.async_read_some
-    ( 
-      boost::asio::buffer(recv_buf_.get_unused_start(),
-        recv_buf_.get_unused_len()),
-      strand_->wrap
-      (
-        boost::bind
-        (
-          &openssl_operation::async_read_handler, 
-          this, 
-          boost::asio::placeholders::error, 
-          boost::asio::placeholders::bytes_transferred
-        )
-      )
-    );
-    return 0;
-  }
-
-  void async_read_handler(const boost::system::error_code& error,
-      size_t bytes_recvd)
-  {
-    if (!error)
-    {
-      recv_buf_.data_added(bytes_recvd);
-
-      // Pass the received data to SSL
-      int written = ::BIO_write
-      ( 
-        ssl_bio_, 
-        recv_buf_.get_data_start(), 
-        recv_buf_.get_data_len() 
-      );
-
-      if (written > 0)
-      {
-        recv_buf_.data_removed(written);
-      }
-      else if (written < 0)
-      {
-        if (!BIO_should_retry(ssl_bio_))
-        {
-          // Some serios error with BIO....
-          handler_(boost::asio::error::no_recovery, 0);
-          return;
-        }
-      }
-
-      // and try the SSL primitive again
-      start();
-    }
-    else
-    {
-      // Error in network level...
-      // SSL can't continue either...
-      handler_(error, 0);
-    }
-  }
-
-  // Syncronous functions...
-  int do_sync_write(bool is_operation_done, int rc)
-  {
-    int len = ::BIO_ctrl_pending( ssl_bio_ );
-    if ( len )
-    { 
-      // There is something to write into net, do it...
-      len = (int)send_buf_.get_unused_len() > len? 
-        len: 
-        send_buf_.get_unused_len();
-        
-      // Read outgoing data from bio
-      len = ::BIO_read( ssl_bio_, send_buf_.get_unused_start(), len); 
-         
-      if (len > 0)
-      {
-        size_t sent_len = boost::asio::write( 
-                  socket_, 
-                  boost::asio::buffer(send_buf_.get_unused_start(), len)
-                  );
-
-        send_buf_.data_added(len);
-        send_buf_.data_removed(sent_len);
-      }          
-      else if (!BIO_should_retry(ssl_bio_))
-      {
-        // Seems like fatal error
-        // reading from SSL BIO has failed...
-        throw boost::system::system_error(boost::asio::error::no_recovery);
-      }
-    }
-    
-    if (is_operation_done)
-      // Finish the operation, with success
-      return rc;
-                
-    // Operation is not finished, start again.
-    return start();
-  }
-
-  int do_sync_read()
-  {
-    size_t len = socket_.read_some
-      ( 
-        boost::asio::buffer(recv_buf_.get_unused_start(),
-          recv_buf_.get_unused_len())
-      );
-
-    // Write data to ssl
-    recv_buf_.data_added(len);
-
-    // Pass the received data to SSL
-    int written = ::BIO_write
-    ( 
-      ssl_bio_, 
-      recv_buf_.get_data_start(), 
-      recv_buf_.get_data_len() 
-    );
-
-    if (written > 0)
-    {
-      recv_buf_.data_removed(written);
-    }
-    else if (written < 0)
-    {
-      if (!BIO_should_retry(ssl_bio_))
-      {
-        // Some serios error with BIO....
-        throw boost::system::system_error(boost::asio::error::no_recovery);
-      }
-    }
-
-    // Try the operation again
-    return start();
-  }
-}; // class openssl_operation
-
-} // namespace detail
-} // namespace old
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_OPERATION_HPP
diff --git a/include/boost/asio/ssl/old/detail/openssl_stream_service.hpp b/include/boost/asio/ssl/old/detail/openssl_stream_service.hpp
deleted file mode 100644
index afccf3652a..0000000000
--- a/include/boost/asio/ssl/old/detail/openssl_stream_service.hpp
+++ /dev/null
@@ -1,573 +0,0 @@
-//
-// ssl/old/detail/stream_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2005 Voipster / Indrek dot Juhani at voipster dot com
-// Copyright (c) 2005-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_STREAM_SERVICE_HPP
-#define BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_STREAM_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <cstddef>
-#include <climits>
-#include <memory>
-#include <boost/config.hpp>
-#include <boost/noncopyable.hpp>
-#include <boost/function.hpp>
-#include <boost/bind.hpp>
-#include <boost/asio/detail/buffer_sequence_adapter.hpp>
-#include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ssl/basic_context.hpp>
-#include <boost/asio/ssl/stream_base.hpp>
-#include <boost/asio/ssl/old/detail/openssl_operation.hpp>
-#include <boost/asio/ssl/detail/openssl_types.hpp>
-#include <boost/asio/strand.hpp>
-#include <boost/system/system_error.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-namespace old {
-namespace detail {
-
-class openssl_stream_service
-  : public boost::asio::detail::service_base<openssl_stream_service>
-{
-private:
-  enum { max_buffer_size = INT_MAX };
-
-  //Base handler for asyncrhonous operations
-  template <typename Stream>
-  class base_handler
-  {
-  public:
-    typedef boost::function<
-      void (const boost::system::error_code&, size_t)> func_t;
-
-    base_handler(boost::asio::io_service& io_service)
-      : op_(NULL)
-      , io_service_(io_service)
-      , work_(io_service)
-    {}
-    
-    void do_func(const boost::system::error_code& error, size_t size)
-    {
-      func_(error, size);
-    }
-        
-    void set_operation(openssl_operation<Stream>* op) { op_ = op; }
-    void set_func(func_t func) { func_ = func; }
-
-    ~base_handler()
-    {
-      delete op_;
-    }
-
-  private:
-    func_t func_;
-    openssl_operation<Stream>* op_;
-    boost::asio::io_service& io_service_;
-    boost::asio::io_service::work work_;
-  };  // class base_handler
-
-  // Handler for asynchronous IO (write/read) operations
-  template<typename Stream, typename Handler>
-  class io_handler 
-    : public base_handler<Stream>
-  {
-  public:
-    io_handler(Handler handler, boost::asio::io_service& io_service)
-      : base_handler<Stream>(io_service)
-      , handler_(handler)
-    {
-      this->set_func(boost::bind(
-        &io_handler<Stream, Handler>::handler_impl, 
-        this, boost::arg<1>(), boost::arg<2>() ));
-    }
-
-  private:
-    Handler handler_;
-    void handler_impl(const boost::system::error_code& error, size_t size)
-    {
-      std::auto_ptr<io_handler<Stream, Handler> > this_ptr(this);
-      handler_(error, size);
-    }
-  };  // class io_handler 
-
-  // Handler for asyncrhonous handshake (connect, accept) functions
-  template <typename Stream, typename Handler>
-  class handshake_handler
-    : public base_handler<Stream>
-  {
-  public:
-    handshake_handler(Handler handler, boost::asio::io_service& io_service)
-      : base_handler<Stream>(io_service)
-      , handler_(handler)
-    {
-      this->set_func(boost::bind(
-        &handshake_handler<Stream, Handler>::handler_impl, 
-        this, boost::arg<1>(), boost::arg<2>() ));
-    }
-
-  private:
-    Handler handler_;
-    void handler_impl(const boost::system::error_code& error, size_t)
-    {
-      std::auto_ptr<handshake_handler<Stream, Handler> > this_ptr(this);
-      handler_(error);
-    }
-
-  };  // class handshake_handler
-
-  // Handler for asyncrhonous shutdown
-  template <typename Stream, typename Handler>
-  class shutdown_handler
-    : public base_handler<Stream>
-  {
-  public:
-    shutdown_handler(Handler handler, boost::asio::io_service& io_service)
-      : base_handler<Stream>(io_service),
-        handler_(handler)
-    { 
-      this->set_func(boost::bind(
-        &shutdown_handler<Stream, Handler>::handler_impl, 
-        this, boost::arg<1>(), boost::arg<2>() ));
-    }
-
-  private:
-    Handler handler_;
-    void handler_impl(const boost::system::error_code& error, size_t)
-    {
-      std::auto_ptr<shutdown_handler<Stream, Handler> > this_ptr(this);
-      handler_(error);
-    }
-  };  // class shutdown_handler
-
-public:
-  // The implementation type.
-  typedef struct impl_struct
-  {
-    ::SSL* ssl;
-    ::BIO* ext_bio;
-    net_buffer recv_buf;
-  } * impl_type;
-
-  // Construct a new stream socket service for the specified io_service.
-  explicit openssl_stream_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<openssl_stream_service>(io_service),
-      strand_(io_service)
-  {
-  }
-
-  // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
-  {
-  }
-
-  // Return a null stream implementation.
-  impl_type null() const
-  {
-    return 0;
-  }
-
-  // Create a new stream implementation.
-  template <typename Stream, typename Context_Service>
-  void create(impl_type& impl, Stream& /*next_layer*/,
-      basic_context<Context_Service>& context)
-  {
-    impl = new impl_struct;
-    impl->ssl = ::SSL_new(context.impl());
-    ::SSL_set_mode(impl->ssl, SSL_MODE_ENABLE_PARTIAL_WRITE);
-    ::SSL_set_mode(impl->ssl, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
-    ::BIO* int_bio = 0;
-    impl->ext_bio = 0;
-    ::BIO_new_bio_pair(&int_bio, 8192, &impl->ext_bio, 8192);
-    ::SSL_set_bio(impl->ssl, int_bio, int_bio);
-  }
-
-  // Destroy a stream implementation.
-  template <typename Stream>
-  void destroy(impl_type& impl, Stream& /*next_layer*/)
-  {
-    if (impl != 0)
-    {
-      ::BIO_free(impl->ext_bio);
-      ::SSL_free(impl->ssl);
-      delete impl;
-      impl = 0;
-    }
-  }
-
-  // Perform SSL handshaking.
-  template <typename Stream>
-  boost::system::error_code handshake(impl_type& impl, Stream& next_layer,
-      stream_base::handshake_type type, boost::system::error_code& ec)
-  {
-    try
-    {
-      openssl_operation<Stream> op(
-        type == stream_base::client ?
-          &ssl_wrap<mutex_type>::SSL_connect:
-          &ssl_wrap<mutex_type>::SSL_accept,
-        next_layer,
-        impl->recv_buf,
-        impl->ssl,
-        impl->ext_bio);
-      op.start();
-    }
-    catch (boost::system::system_error& e)
-    {
-      ec = e.code();
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Start an asynchronous SSL handshake.
-  template <typename Stream, typename Handler>
-  void async_handshake(impl_type& impl, Stream& next_layer,
-      stream_base::handshake_type type, Handler handler)
-  {
-    typedef handshake_handler<Stream, Handler> connect_handler;
-
-    connect_handler* local_handler = 
-      new connect_handler(handler, get_io_service());
-
-    openssl_operation<Stream>* op = new openssl_operation<Stream>
-    (
-      type == stream_base::client ?
-        &ssl_wrap<mutex_type>::SSL_connect:
-        &ssl_wrap<mutex_type>::SSL_accept,
-      next_layer,
-      impl->recv_buf,
-      impl->ssl,
-      impl->ext_bio,
-      boost::bind
-      (
-        &base_handler<Stream>::do_func, 
-        local_handler,
-        boost::arg<1>(),
-        boost::arg<2>()
-      ),
-      strand_
-    );
-    local_handler->set_operation(op);
-
-    strand_.post(boost::bind(&openssl_operation<Stream>::start, op));
-  }
-
-  // Shut down SSL on the stream.
-  template <typename Stream>
-  boost::system::error_code shutdown(impl_type& impl, Stream& next_layer,
-      boost::system::error_code& ec)
-  {
-    try
-    {
-      openssl_operation<Stream> op(
-        &ssl_wrap<mutex_type>::SSL_shutdown,
-        next_layer,
-        impl->recv_buf,
-        impl->ssl,
-        impl->ext_bio);
-      op.start();
-    }
-    catch (boost::system::system_error& e)
-    {
-      ec = e.code();
-      return ec;
-    }
-
-    ec = boost::system::error_code();
-    return ec;
-  }
-
-  // Asynchronously shut down SSL on the stream.
-  template <typename Stream, typename Handler>
-  void async_shutdown(impl_type& impl, Stream& next_layer, Handler handler)
-  {
-    typedef shutdown_handler<Stream, Handler> disconnect_handler;
-
-    disconnect_handler* local_handler = 
-      new disconnect_handler(handler, get_io_service());
-
-    openssl_operation<Stream>* op = new openssl_operation<Stream>
-    (
-      &ssl_wrap<mutex_type>::SSL_shutdown,
-      next_layer,
-      impl->recv_buf,
-      impl->ssl,
-      impl->ext_bio,
-      boost::bind
-      (
-        &base_handler<Stream>::do_func, 
-        local_handler, 
-        boost::arg<1>(),
-        boost::arg<2>()
-      ),
-      strand_
-    );
-    local_handler->set_operation(op);
-
-    strand_.post(boost::bind(&openssl_operation<Stream>::start, op));        
-  }
-
-  // Write some data to the stream.
-  template <typename Stream, typename Const_Buffers>
-  std::size_t write_some(impl_type& impl, Stream& next_layer,
-      const Const_Buffers& buffers, boost::system::error_code& ec)
-  {
-    size_t bytes_transferred = 0;
-    try
-    {
-      boost::asio::const_buffer buffer =
-        boost::asio::detail::buffer_sequence_adapter<
-          boost::asio::const_buffer, Const_Buffers>::first(buffers);
-
-      std::size_t buffer_size = boost::asio::buffer_size(buffer);
-      if (buffer_size > max_buffer_size)
-        buffer_size = max_buffer_size;
-      else if (buffer_size == 0)
-      {
-        ec = boost::system::error_code();
-        return 0;
-      }
-
-      boost::function<int (SSL*)> send_func =
-        boost::bind(boost::type<int>(), &::SSL_write, boost::arg<1>(),  
-            boost::asio::buffer_cast<const void*>(buffer),
-            static_cast<int>(buffer_size));
-      openssl_operation<Stream> op(
-        send_func,
-        next_layer,
-        impl->recv_buf,
-        impl->ssl,
-        impl->ext_bio
-      );
-      bytes_transferred = static_cast<size_t>(op.start());
-    }
-    catch (boost::system::system_error& e)
-    {
-      ec = e.code();
-      return 0;
-    }
-
-    ec = boost::system::error_code();
-    return bytes_transferred;
-  }
-
-  // Start an asynchronous write.
-  template <typename Stream, typename Const_Buffers, typename Handler>
-  void async_write_some(impl_type& impl, Stream& next_layer,
-      const Const_Buffers& buffers, Handler handler)
-  {
-    typedef io_handler<Stream, Handler> send_handler;
-
-    boost::asio::const_buffer buffer =
-      boost::asio::detail::buffer_sequence_adapter<
-        boost::asio::const_buffer, Const_Buffers>::first(buffers);
-
-    std::size_t buffer_size = boost::asio::buffer_size(buffer);
-    if (buffer_size > max_buffer_size)
-      buffer_size = max_buffer_size;
-    else if (buffer_size == 0)
-    {
-      get_io_service().post(boost::asio::detail::bind_handler(
-            handler, boost::system::error_code(), 0));
-      return;
-    }
-
-    send_handler* local_handler = new send_handler(handler, get_io_service());
-
-    boost::function<int (SSL*)> send_func =
-      boost::bind(boost::type<int>(), &::SSL_write, boost::arg<1>(),
-          boost::asio::buffer_cast<const void*>(buffer),
-          static_cast<int>(buffer_size));
-
-    openssl_operation<Stream>* op = new openssl_operation<Stream>
-    (
-      send_func,
-      next_layer,
-      impl->recv_buf,
-      impl->ssl,
-      impl->ext_bio,
-      boost::bind
-      (
-        &base_handler<Stream>::do_func, 
-        local_handler, 
-        boost::arg<1>(),
-        boost::arg<2>()
-      ),
-      strand_
-    );
-    local_handler->set_operation(op);
-
-    strand_.post(boost::bind(&openssl_operation<Stream>::start, op));        
-  }
-
-  // Read some data from the stream.
-  template <typename Stream, typename Mutable_Buffers>
-  std::size_t read_some(impl_type& impl, Stream& next_layer,
-      const Mutable_Buffers& buffers, boost::system::error_code& ec)
-  {
-    size_t bytes_transferred = 0;
-    try
-    {
-      boost::asio::mutable_buffer buffer =
-        boost::asio::detail::buffer_sequence_adapter<
-          boost::asio::mutable_buffer, Mutable_Buffers>::first(buffers);
-
-      std::size_t buffer_size = boost::asio::buffer_size(buffer);
-      if (buffer_size > max_buffer_size)
-        buffer_size = max_buffer_size;
-      else if (buffer_size == 0)
-      {
-        ec = boost::system::error_code();
-        return 0;
-      }
-
-      boost::function<int (SSL*)> recv_func =
-        boost::bind(boost::type<int>(), &::SSL_read, boost::arg<1>(),
-            boost::asio::buffer_cast<void*>(buffer),
-            static_cast<int>(buffer_size));
-      openssl_operation<Stream> op(recv_func,
-        next_layer,
-        impl->recv_buf,
-        impl->ssl,
-        impl->ext_bio
-      );
-
-      bytes_transferred = static_cast<size_t>(op.start());
-    }
-    catch (boost::system::system_error& e)
-    {
-      ec = e.code();
-      return 0;
-    }
-
-    ec = boost::system::error_code();
-    return bytes_transferred;
-  }
-
-  // Start an asynchronous read.
-  template <typename Stream, typename Mutable_Buffers, typename Handler>
-  void async_read_some(impl_type& impl, Stream& next_layer,
-      const Mutable_Buffers& buffers, Handler handler)
-  {
-    typedef io_handler<Stream, Handler> recv_handler;
-
-    boost::asio::mutable_buffer buffer =
-      boost::asio::detail::buffer_sequence_adapter<
-        boost::asio::mutable_buffer, Mutable_Buffers>::first(buffers);
-
-    std::size_t buffer_size = boost::asio::buffer_size(buffer);
-    if (buffer_size > max_buffer_size)
-      buffer_size = max_buffer_size;
-    else if (buffer_size == 0)
-    {
-      get_io_service().post(boost::asio::detail::bind_handler(
-            handler, boost::system::error_code(), 0));
-      return;
-    }
-
-    recv_handler* local_handler = new recv_handler(handler, get_io_service());
-
-    boost::function<int (SSL*)> recv_func =
-      boost::bind(boost::type<int>(), &::SSL_read, boost::arg<1>(),
-          boost::asio::buffer_cast<void*>(buffer),
-          static_cast<int>(buffer_size));
-
-    openssl_operation<Stream>* op = new openssl_operation<Stream>
-    (
-      recv_func,
-      next_layer,
-      impl->recv_buf,
-      impl->ssl,
-      impl->ext_bio,
-      boost::bind
-      (
-        &base_handler<Stream>::do_func, 
-        local_handler, 
-        boost::arg<1>(),
-        boost::arg<2>()
-      ),
-      strand_
-    );
-    local_handler->set_operation(op);
-
-    strand_.post(boost::bind(&openssl_operation<Stream>::start, op));        
-  }
-
-  // Peek at the incoming data on the stream.
-  template <typename Stream, typename Mutable_Buffers>
-  std::size_t peek(impl_type& /*impl*/, Stream& /*next_layer*/,
-      const Mutable_Buffers& /*buffers*/, boost::system::error_code& ec)
-  {
-    ec = boost::system::error_code();
-    return 0;
-  }
-
-  // Determine the amount of data that may be read without blocking.
-  template <typename Stream>
-  std::size_t in_avail(impl_type& /*impl*/, Stream& /*next_layer*/,
-      boost::system::error_code& ec)
-  {
-    ec = boost::system::error_code();
-    return 0;
-  }
-
-private:  
-  boost::asio::io_service::strand strand_;
-
-  typedef boost::asio::detail::mutex mutex_type;
-  
-  template<typename Mutex>
-  struct ssl_wrap
-  {
-    static Mutex ssl_mutex_;
-
-    static int SSL_accept(SSL *ssl)
-    {
-      typename Mutex::scoped_lock lock(ssl_mutex_);
-      return ::SSL_accept(ssl);
-    }
-  
-    static int SSL_connect(SSL *ssl)
-    {
-      typename Mutex::scoped_lock lock(ssl_mutex_);
-      return ::SSL_connect(ssl);
-    }
-  
-    static int SSL_shutdown(SSL *ssl)
-    {
-      typename Mutex::scoped_lock lock(ssl_mutex_);
-      return ::SSL_shutdown(ssl);  
-    }    
-  };  
-};
-
-template<typename Mutex>
-Mutex openssl_stream_service::ssl_wrap<Mutex>::ssl_mutex_;
-
-} // namespace detail
-} // namespace old
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_OLD_DETAIL_OPENSSL_STREAM_SERVICE_HPP
diff --git a/include/boost/asio/ssl/old/stream.hpp b/include/boost/asio/ssl/old/stream.hpp
deleted file mode 100644
index a8c570ee08..0000000000
--- a/include/boost/asio/ssl/old/stream.hpp
+++ /dev/null
@@ -1,503 +0,0 @@
-//
-// ssl/old/stream.hpp
-// ~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2005 Voipster / Indrek dot Juhani at voipster dot com
-// Copyright (c) 2005-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_OLD_STREAM_HPP
-#define BOOST_ASIO_SSL_OLD_STREAM_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <cstddef>
-#include <boost/noncopyable.hpp>
-#include <boost/asio/detail/throw_error.hpp>
-#include <boost/asio/detail/type_traits.hpp>
-#include <boost/asio/error.hpp>
-#include <boost/asio/ssl/basic_context.hpp>
-#include <boost/asio/ssl/stream_base.hpp>
-#include <boost/asio/ssl/stream_service.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-namespace old {
-
-/// Provides stream-oriented functionality using SSL.
-/**
- * The stream class template provides asynchronous and blocking stream-oriented
- * functionality using SSL.
- *
- * @par Thread Safety
- * @e Distinct @e objects: Safe.@n
- * @e Shared @e objects: Unsafe.
- *
- * @par Example
- * To use the SSL stream template with an ip::tcp::socket, you would write:
- * @code
- * boost::asio::io_service io_service;
- * boost::asio::ssl::context context(io_service, boost::asio::ssl::context::sslv23);
- * boost::asio::ssl::stream<boost::asio::ip::tcp::socket> sock(io_service, context);
- * @endcode
- *
- * @par Concepts:
- * AsyncReadStream, AsyncWriteStream, Stream, SyncRead_Stream, SyncWriteStream.
- */
-template <typename Stream, typename Service = old::stream_service>
-class stream
-  : public stream_base,
-    private boost::noncopyable
-{
-public:
-  /// The type of the next layer.
-  typedef typename remove_reference<Stream>::type next_layer_type;
-
-  /// The type of the lowest layer.
-  typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
-
-  /// The type of the service that will be used to provide stream operations.
-  typedef Service service_type;
-
-  /// The native implementation type of the stream.
-  typedef typename service_type::impl_type impl_type;
-
-  /// Construct a stream.
-  /**
-   * This constructor creates a stream and initialises the underlying stream
-   * object.
-   *
-   * @param arg The argument to be passed to initialise the underlying stream.
-   *
-   * @param context The SSL context to be used for the stream.
-   */
-  template <typename Arg, typename Context_Service>
-  explicit stream(Arg& arg, basic_context<Context_Service>& context)
-    : next_layer_(arg),
-      service_(boost::asio::use_service<Service>(next_layer_.get_io_service())),
-      impl_(service_.null())
-  {
-    service_.create(impl_, next_layer_, context);
-  }
-
-  /// Destructor.
-  ~stream()
-  {
-    service_.destroy(impl_, next_layer_);
-  }
-
-  /// Get the io_service associated with the object.
-  /**
-   * This function may be used to obtain the io_service object that the stream
-   * uses to dispatch handlers for asynchronous operations.
-   *
-   * @return A reference to the io_service object that stream will use to
-   * dispatch handlers. Ownership is not transferred to the caller.
-   */
-  boost::asio::io_service& get_io_service()
-  {
-    return next_layer_.get_io_service();
-  }
-
-  /// Get a reference to the next layer.
-  /**
-   * This function returns a reference to the next layer in a stack of stream
-   * layers.
-   *
-   * @return A reference to the next layer in the stack of stream layers.
-   * Ownership is not transferred to the caller.
-   */
-  next_layer_type& next_layer()
-  {
-    return next_layer_;
-  }
-
-  /// Get a reference to the lowest layer.
-  /**
-   * This function returns a reference to the lowest layer in a stack of
-   * stream layers.
-   *
-   * @return A reference to the lowest layer in the stack of stream layers.
-   * Ownership is not transferred to the caller.
-   */
-  lowest_layer_type& lowest_layer()
-  {
-    return next_layer_.lowest_layer();
-  }
-
-  /// Get a const reference to the lowest layer.
-  /**
-   * This function returns a const reference to the lowest layer in a stack of
-   * stream layers.
-   *
-   * @return A const reference to the lowest layer in the stack of stream
-   * layers. Ownership is not transferred to the caller.
-   */
-  const lowest_layer_type& lowest_layer() const
-  {
-    return next_layer_.lowest_layer();
-  }
-
-  /// Get the underlying implementation in the native type.
-  /**
-   * This function may be used to obtain the underlying implementation of the
-   * context. This is intended to allow access to stream functionality that is
-   * not otherwise provided.
-   */
-  impl_type impl()
-  {
-    return impl_;
-  }
-
-  /// Perform SSL handshaking.
-  /**
-   * This function is used to perform SSL handshaking on the stream. The
-   * function call will block until handshaking is complete or an error occurs.
-   *
-   * @param type The type of handshaking to be performed, i.e. as a client or as
-   * a server.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void handshake(handshake_type type)
-  {
-    boost::system::error_code ec;
-    service_.handshake(impl_, next_layer_, type, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Perform SSL handshaking.
-  /**
-   * This function is used to perform SSL handshaking on the stream. The
-   * function call will block until handshaking is complete or an error occurs.
-   *
-   * @param type The type of handshaking to be performed, i.e. as a client or as
-   * a server.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code handshake(handshake_type type,
-      boost::system::error_code& ec)
-  {
-    return service_.handshake(impl_, next_layer_, type, ec);
-  }
-
-  /// Start an asynchronous SSL handshake.
-  /**
-   * This function is used to asynchronously perform an SSL handshake on the
-   * stream. This function call always returns immediately.
-   *
-   * @param type The type of handshaking to be performed, i.e. as a client or as
-   * a server.
-   *
-   * @param handler The handler to be called when the handshake operation
-   * completes. Copies will be made of the handler as required. The equivalent
-   * function signature of the handler must be:
-   * @code void handler(
-   *   const boost::system::error_code& error // Result of operation.
-   * ); @endcode
-   */
-  template <typename HandshakeHandler>
-  void async_handshake(handshake_type type, HandshakeHandler handler)
-  {
-    service_.async_handshake(impl_, next_layer_, type, handler);
-  }
-
-  /// Shut down SSL on the stream.
-  /**
-   * This function is used to shut down SSL on the stream. The function call
-   * will block until SSL has been shut down or an error occurs.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  void shutdown()
-  {
-    boost::system::error_code ec;
-    service_.shutdown(impl_, next_layer_, ec);
-    boost::asio::detail::throw_error(ec);
-  }
-
-  /// Shut down SSL on the stream.
-  /**
-   * This function is used to shut down SSL on the stream. The function call
-   * will block until SSL has been shut down or an error occurs.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   */
-  boost::system::error_code shutdown(boost::system::error_code& ec)
-  {
-    return service_.shutdown(impl_, next_layer_, ec);
-  }
-
-  /// Asynchronously shut down SSL on the stream.
-  /**
-   * This function is used to asynchronously shut down SSL on the stream. This
-   * function call always returns immediately.
-   *
-   * @param handler The handler to be called when the handshake operation
-   * completes. Copies will be made of the handler as required. The equivalent
-   * function signature of the handler must be:
-   * @code void handler(
-   *   const boost::system::error_code& error // Result of operation.
-   * ); @endcode
-   */
-  template <typename ShutdownHandler>
-  void async_shutdown(ShutdownHandler handler)
-  {
-    service_.async_shutdown(impl_, next_layer_, handler);
-  }
-
-  /// Write some data to the stream.
-  /**
-   * This function is used to write data on the stream. The function call will
-   * block until one or more bytes of data has been written successfully, or
-   * until an error occurs.
-   *
-   * @param buffers The data to be written.
-   *
-   * @returns The number of bytes written.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   *
-   * @note The write_some operation may not transmit all of the data to the
-   * peer. Consider using the @ref write function if you need to ensure that all
-   * data is written before the blocking operation completes.
-   */
-  template <typename ConstBufferSequence>
-  std::size_t write_some(const ConstBufferSequence& buffers)
-  {
-    boost::system::error_code ec;
-    std::size_t s = service_.write_some(impl_, next_layer_, buffers, ec);
-    boost::asio::detail::throw_error(ec);
-    return s;
-  }
-
-  /// Write some data to the stream.
-  /**
-   * This function is used to write data on the stream. The function call will
-   * block until one or more bytes of data has been written successfully, or
-   * until an error occurs.
-   *
-   * @param buffers The data to be written to the stream.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   *
-   * @returns The number of bytes written. Returns 0 if an error occurred.
-   *
-   * @note The write_some operation may not transmit all of the data to the
-   * peer. Consider using the @ref write function if you need to ensure that all
-   * data is written before the blocking operation completes.
-   */
-  template <typename ConstBufferSequence>
-  std::size_t write_some(const ConstBufferSequence& buffers,
-      boost::system::error_code& ec)
-  {
-    return service_.write_some(impl_, next_layer_, buffers, ec);
-  }
-
-  /// Start an asynchronous write.
-  /**
-   * This function is used to asynchronously write one or more bytes of data to
-   * the stream. The function call always returns immediately.
-   *
-   * @param buffers The data to be written to the stream. Although the buffers
-   * object may be copied as necessary, ownership of the underlying buffers is
-   * retained by the caller, which must guarantee that they remain valid until
-   * the handler is called.
-   *
-   * @param handler The handler to be called when the write operation completes.
-   * Copies will be made of the handler as required. The equivalent function
-   * signature of the handler must be:
-   * @code void handler(
-   *   const boost::system::error_code& error, // Result of operation.
-   *   std::size_t bytes_transferred           // Number of bytes written.
-   * ); @endcode
-   *
-   * @note The async_write_some operation may not transmit all of the data to
-   * the peer. Consider using the @ref async_write function if you need to
-   * ensure that all data is written before the blocking operation completes.
-   */
-  template <typename ConstBufferSequence, typename WriteHandler>
-  void async_write_some(const ConstBufferSequence& buffers,
-      WriteHandler handler)
-  {
-    service_.async_write_some(impl_, next_layer_, buffers, handler);
-  }
-
-  /// Read some data from the stream.
-  /**
-   * This function is used to read data from the stream. The function call will
-   * block until one or more bytes of data has been read successfully, or until
-   * an error occurs.
-   *
-   * @param buffers The buffers into which the data will be read.
-   *
-   * @returns The number of bytes read.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   *
-   * @note The read_some operation may not read all of the requested number of
-   * bytes. Consider using the @ref read function if you need to ensure that the
-   * requested amount of data is read before the blocking operation completes.
-   */
-  template <typename MutableBufferSequence>
-  std::size_t read_some(const MutableBufferSequence& buffers)
-  {
-    boost::system::error_code ec;
-    std::size_t s = service_.read_some(impl_, next_layer_, buffers, ec);
-    boost::asio::detail::throw_error(ec);
-    return s;
-  }
-
-  /// Read some data from the stream.
-  /**
-   * This function is used to read data from the stream. The function call will
-   * block until one or more bytes of data has been read successfully, or until
-   * an error occurs.
-   *
-   * @param buffers The buffers into which the data will be read.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   *
-   * @returns The number of bytes read. Returns 0 if an error occurred.
-   *
-   * @note The read_some operation may not read all of the requested number of
-   * bytes. Consider using the @ref read function if you need to ensure that the
-   * requested amount of data is read before the blocking operation completes.
-   */
-  template <typename MutableBufferSequence>
-  std::size_t read_some(const MutableBufferSequence& buffers,
-      boost::system::error_code& ec)
-  {
-    return service_.read_some(impl_, next_layer_, buffers, ec);
-  }
-
-  /// Start an asynchronous read.
-  /**
-   * This function is used to asynchronously read one or more bytes of data from
-   * the stream. The function call always returns immediately.
-   *
-   * @param buffers The buffers into which the data will be read. Although the
-   * buffers object may be copied as necessary, ownership of the underlying
-   * buffers is retained by the caller, which must guarantee that they remain
-   * valid until the handler is called.
-   *
-   * @param handler The handler to be called when the read operation completes.
-   * Copies will be made of the handler as required. The equivalent function
-   * signature of the handler must be:
-   * @code void handler(
-   *   const boost::system::error_code& error, // Result of operation.
-   *   std::size_t bytes_transferred           // Number of bytes read.
-   * ); @endcode
-   *
-   * @note The async_read_some operation may not read all of the requested
-   * number of bytes. Consider using the @ref async_read function if you need to
-   * ensure that the requested amount of data is read before the asynchronous
-   * operation completes.
-   */
-  template <typename MutableBufferSequence, typename ReadHandler>
-  void async_read_some(const MutableBufferSequence& buffers,
-      ReadHandler handler)
-  {
-    service_.async_read_some(impl_, next_layer_, buffers, handler);
-  }
-
-  /// Peek at the incoming data on the stream.
-  /**
-   * This function is used to peek at the incoming data on the stream, without
-   * removing it from the input queue. The function call will block until data
-   * has been read successfully or an error occurs.
-   *
-   * @param buffers The buffers into which the data will be read.
-   *
-   * @returns The number of bytes read.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  template <typename MutableBufferSequence>
-  std::size_t peek(const MutableBufferSequence& buffers)
-  {
-    boost::system::error_code ec;
-    std::size_t s = service_.peek(impl_, next_layer_, buffers, ec);
-    boost::asio::detail::throw_error(ec);
-    return s;
-  }
-
-  /// Peek at the incoming data on the stream.
-  /**
-   * This function is used to peek at the incoming data on the stream, withoutxi
-   * removing it from the input queue. The function call will block until data
-   * has been read successfully or an error occurs.
-   *
-   * @param buffers The buffers into which the data will be read.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   *
-   * @returns The number of bytes read. Returns 0 if an error occurred.
-   */
-  template <typename MutableBufferSequence>
-  std::size_t peek(const MutableBufferSequence& buffers,
-      boost::system::error_code& ec)
-  {
-    return service_.peek(impl_, next_layer_, buffers, ec);
-  }
-
-  /// Determine the amount of data that may be read without blocking.
-  /**
-   * This function is used to determine the amount of data, in bytes, that may
-   * be read from the stream without blocking.
-   *
-   * @returns The number of bytes of data that can be read without blocking.
-   *
-   * @throws boost::system::system_error Thrown on failure.
-   */
-  std::size_t in_avail()
-  {
-    boost::system::error_code ec;
-    std::size_t s = service_.in_avail(impl_, next_layer_, ec);
-    boost::asio::detail::throw_error(ec);
-    return s;
-  }
-
-  /// Determine the amount of data that may be read without blocking.
-  /**
-   * This function is used to determine the amount of data, in bytes, that may
-   * be read from the stream without blocking.
-   *
-   * @param ec Set to indicate what error occurred, if any.
-   *
-   * @returns The number of bytes of data that can be read without blocking.
-   */
-  std::size_t in_avail(boost::system::error_code& ec)
-  {
-    return service_.in_avail(impl_, next_layer_, ec);
-  }
-
-private:
-  /// The next layer.
-  Stream next_layer_;
-
-  /// The backend service implementation.
-  service_type& service_;
-
-  /// The underlying native implementation.
-  impl_type impl_;
-};
-
-} // namespace old
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_OLD_STREAM_HPP
diff --git a/include/boost/asio/ssl/old/stream_service.hpp b/include/boost/asio/ssl/old/stream_service.hpp
deleted file mode 100644
index 282687c2ea..0000000000
--- a/include/boost/asio/ssl/old/stream_service.hpp
+++ /dev/null
@@ -1,186 +0,0 @@
-//
-// ssl/old/stream_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2005 Voipster / Indrek dot Juhani at voipster dot com
-// Copyright (c) 2005-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_OLD_STREAM_SERVICE_HPP
-#define BOOST_ASIO_SSL_OLD_STREAM_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-#include <cstddef>
-#include <boost/noncopyable.hpp>
-#include <boost/asio/io_service.hpp>
-#include <boost/asio/ssl/basic_context.hpp>
-#include <boost/asio/ssl/old/detail/openssl_stream_service.hpp>
-#include <boost/asio/ssl/stream_base.hpp>
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-namespace old {
-
-/// Default service implementation for an SSL stream.
-class stream_service
-#if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
-#else
-  : public boost::asio::detail::service_base<stream_service>
-#endif
-{
-private:
-  // The type of the platform-specific implementation.
-  typedef old::detail::openssl_stream_service service_impl_type;
-
-public:
-#if defined(GENERATING_DOCUMENTATION)
-  /// The unique service identifier.
-  static boost::asio::io_service::id id;
-#endif
-
-  /// The type of a stream implementation.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined impl_type;
-#else
-  typedef service_impl_type::impl_type impl_type;
-#endif
-
-  /// Construct a new stream service for the specified io_service.
-  explicit stream_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<stream_service>(io_service),
-      service_impl_(boost::asio::use_service<service_impl_type>(io_service))
-  {
-  }
-
-  /// Return a null stream implementation.
-  impl_type null() const
-  {
-    return service_impl_.null();
-  }
-
-  /// Create a new stream implementation.
-  template <typename Stream, typename Context_Service>
-  void create(impl_type& impl, Stream& next_layer,
-      basic_context<Context_Service>& context)
-  {
-    service_impl_.create(impl, next_layer, context);
-  }
-
-  /// Destroy a stream implementation.
-  template <typename Stream>
-  void destroy(impl_type& impl, Stream& next_layer)
-  {
-    service_impl_.destroy(impl, next_layer);
-  }
-
-  /// Perform SSL handshaking.
-  template <typename Stream>
-  boost::system::error_code handshake(impl_type& impl, Stream& next_layer,
-      stream_base::handshake_type type, boost::system::error_code& ec)
-  {
-    return service_impl_.handshake(impl, next_layer, type, ec);
-  }
-
-  /// Start an asynchronous SSL handshake.
-  template <typename Stream, typename HandshakeHandler>
-  void async_handshake(impl_type& impl, Stream& next_layer,
-      stream_base::handshake_type type, HandshakeHandler handler)
-  {
-    service_impl_.async_handshake(impl, next_layer, type, handler);
-  }
-
-  /// Shut down SSL on the stream.
-  template <typename Stream>
-  boost::system::error_code shutdown(impl_type& impl, Stream& next_layer,
-      boost::system::error_code& ec)
-  {
-    return service_impl_.shutdown(impl, next_layer, ec);
-  }
-
-  /// Asynchronously shut down SSL on the stream.
-  template <typename Stream, typename ShutdownHandler>
-  void async_shutdown(impl_type& impl, Stream& next_layer,
-      ShutdownHandler handler)
-  {
-    service_impl_.async_shutdown(impl, next_layer, handler);
-  }
-
-  /// Write some data to the stream.
-  template <typename Stream, typename ConstBufferSequence>
-  std::size_t write_some(impl_type& impl, Stream& next_layer,
-      const ConstBufferSequence& buffers, boost::system::error_code& ec)
-  {
-    return service_impl_.write_some(impl, next_layer, buffers, ec);
-  }
-
-  /// Start an asynchronous write.
-  template <typename Stream, typename ConstBufferSequence,
-      typename WriteHandler>
-  void async_write_some(impl_type& impl, Stream& next_layer,
-      const ConstBufferSequence& buffers, WriteHandler handler)
-  {
-    service_impl_.async_write_some(impl, next_layer, buffers, handler);
-  }
-
-  /// Read some data from the stream.
-  template <typename Stream, typename MutableBufferSequence>
-  std::size_t read_some(impl_type& impl, Stream& next_layer,
-      const MutableBufferSequence& buffers, boost::system::error_code& ec)
-  {
-    return service_impl_.read_some(impl, next_layer, buffers, ec);
-  }
-
-  /// Start an asynchronous read.
-  template <typename Stream, typename MutableBufferSequence,
-      typename ReadHandler>
-  void async_read_some(impl_type& impl, Stream& next_layer,
-      const MutableBufferSequence& buffers, ReadHandler handler)
-  {
-    service_impl_.async_read_some(impl, next_layer, buffers, handler);
-  }
-
-  /// Peek at the incoming data on the stream.
-  template <typename Stream, typename MutableBufferSequence>
-  std::size_t peek(impl_type& impl, Stream& next_layer,
-      const MutableBufferSequence& buffers, boost::system::error_code& ec)
-  {
-    return service_impl_.peek(impl, next_layer, buffers, ec);
-  }
-
-  /// Determine the amount of data that may be read without blocking.
-  template <typename Stream>
-  std::size_t in_avail(impl_type& impl, Stream& next_layer,
-      boost::system::error_code& ec)
-  {
-    return service_impl_.in_avail(impl, next_layer, ec);
-  }
-
-private:
-  // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
-  {
-  }
-
-  // The service that provides the platform-specific implementation.
-  service_impl_type& service_impl_;
-};
-
-} // namespace old
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_OLD_STREAM_SERVICE_HPP
diff --git a/include/boost/asio/ssl/rfc2818_verification.hpp b/include/boost/asio/ssl/rfc2818_verification.hpp
index 21b0bca317..62919d79bf 100644
--- a/include/boost/asio/ssl/rfc2818_verification.hpp
+++ b/include/boost/asio/ssl/rfc2818_verification.hpp
@@ -17,11 +17,9 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <string>
-# include <boost/asio/ssl/detail/openssl_types.hpp>
-# include <boost/asio/ssl/verify_context.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <string>
+#include <boost/asio/ssl/detail/openssl_types.hpp>
+#include <boost/asio/ssl/verify_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -29,8 +27,6 @@ namespace boost {
 namespace asio {
 namespace ssl {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 /// Verifies a certificate against a hostname according to the rules described
 /// in RFC 2818.
 /**
@@ -47,9 +43,9 @@ namespace ssl {
  * ctx.set_default_verify_paths();
  *
  * // Open a socket and connect it to the remote host.
- * boost::asio::io_service io_service;
- * ssl_socket sock(io_service, ctx);
- * tcp::resolver resolver(io_service);
+ * boost::asio::io_context io_context;
+ * ssl_socket sock(io_context, ctx);
+ * tcp::resolver resolver(io_context);
  * tcp::resolver::query query("host.name", "https");
  * boost::asio::connect(sock.lowest_layer(), resolver.resolve(query));
  * sock.lowest_layer().set_option(tcp::no_delay(true));
@@ -87,8 +83,6 @@ class rfc2818_verification
   std::string host_;
 };
 
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace ssl
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/ssl/stream.hpp b/include/boost/asio/ssl/stream.hpp
index 1b883d3245..860538156c 100644
--- a/include/boost/asio/ssl/stream.hpp
+++ b/include/boost/asio/ssl/stream.hpp
@@ -17,24 +17,20 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/old/stream.hpp>
-#else // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/async_result.hpp>
-# include <boost/asio/detail/buffer_sequence_adapter.hpp>
-# include <boost/asio/detail/handler_type_requirements.hpp>
-# include <boost/asio/detail/noncopyable.hpp>
-# include <boost/asio/detail/type_traits.hpp>
-# include <boost/asio/ssl/context.hpp>
-# include <boost/asio/ssl/detail/buffered_handshake_op.hpp>
-# include <boost/asio/ssl/detail/handshake_op.hpp>
-# include <boost/asio/ssl/detail/io.hpp>
-# include <boost/asio/ssl/detail/read_op.hpp>
-# include <boost/asio/ssl/detail/shutdown_op.hpp>
-# include <boost/asio/ssl/detail/stream_core.hpp>
-# include <boost/asio/ssl/detail/write_op.hpp>
-# include <boost/asio/ssl/stream_base.hpp>
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/detail/buffer_sequence_adapter.hpp>
+#include <boost/asio/detail/handler_type_requirements.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+#include <boost/asio/ssl/context.hpp>
+#include <boost/asio/ssl/detail/buffered_handshake_op.hpp>
+#include <boost/asio/ssl/detail/handshake_op.hpp>
+#include <boost/asio/ssl/detail/io.hpp>
+#include <boost/asio/ssl/detail/read_op.hpp>
+#include <boost/asio/ssl/detail/shutdown_op.hpp>
+#include <boost/asio/ssl/detail/stream_core.hpp>
+#include <boost/asio/ssl/detail/write_op.hpp>
+#include <boost/asio/ssl/stream_base.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -42,12 +38,6 @@ namespace boost {
 namespace asio {
 namespace ssl {
 
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-using boost::asio::ssl::old::stream;
-
-#else // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 /// Provides stream-oriented functionality using SSL.
 /**
  * The stream class template provides asynchronous and blocking stream-oriented
@@ -62,9 +52,9 @@ using boost::asio::ssl::old::stream;
  * @par Example
  * To use the SSL stream template with an ip::tcp::socket, you would write:
  * @code
- * boost::asio::io_service io_service;
+ * boost::asio::io_context io_context;
  * boost::asio::ssl::context ctx(boost::asio::ssl::context::sslv23);
- * boost::asio::ssl::stream<asio:ip::tcp::socket> sock(io_service, ctx);
+ * boost::asio::ssl::stream<asio:ip::tcp::socket> sock(io_context, ctx);
  * @endcode
  *
  * @par Concepts:
@@ -85,15 +75,16 @@ class stream :
     SSL* ssl;
   };
 
-  /// (Deprecated: Use native_handle_type.) The underlying implementation type.
-  typedef impl_struct* impl_type;
-
   /// The type of the next layer.
   typedef typename remove_reference<Stream>::type next_layer_type;
 
   /// The type of the lowest layer.
   typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
 
+  /// The type of the executor associated with the object.
+  typedef typename lowest_layer_type::executor_type executor_type;
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
   /// Construct a stream.
   /**
    * This constructor creates a stream and initialises the underlying stream
@@ -104,30 +95,58 @@ class stream :
    * @param ctx The SSL context to be used for the stream.
    */
   template <typename Arg>
+  stream(Arg&& arg, context& ctx)
+    : next_layer_(BOOST_ASIO_MOVE_CAST(Arg)(arg)),
+      core_(ctx.native_handle(),
+          next_layer_.lowest_layer().get_executor().context())
+  {
+  }
+#else // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  template <typename Arg>
   stream(Arg& arg, context& ctx)
     : next_layer_(arg),
-      core_(ctx.native_handle(), next_layer_.lowest_layer().get_io_service())
+      core_(ctx.native_handle(),
+          next_layer_.lowest_layer().get_executor().context())
   {
-    backwards_compatible_impl_.ssl = core_.engine_.native_handle();
   }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 
   /// Destructor.
+  /**
+   * @note A @c stream object must not be destroyed while there are pending
+   * asynchronous operations associated with it.
+   */
   ~stream()
   {
   }
 
-  /// Get the io_service associated with the object.
+  /// Get the executor associated with the object.
   /**
-   * This function may be used to obtain the io_service object that the stream
+   * This function may be used to obtain the executor object that the stream
    * uses to dispatch handlers for asynchronous operations.
    *
-   * @return A reference to the io_service object that stream will use to
-   * dispatch handlers. Ownership is not transferred to the caller.
+   * @return A copy of the executor that stream will use to dispatch handlers.
    */
-  boost::asio::io_service& get_io_service()
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return next_layer_.lowest_layer().get_executor();
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_context()
+  {
+    return next_layer_.lowest_layer().get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  boost::asio::io_context& get_io_service()
   {
     return next_layer_.lowest_layer().get_io_service();
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   /// Get the underlying implementation in the native type.
   /**
@@ -140,7 +159,7 @@ class stream :
    * suitable for passing to functions such as @c SSL_get_verify_result and
    * @c SSL_get_peer_certificate:
    * @code
-   * boost::asio::ssl::stream<asio:ip::tcp::socket> sock(io_service, ctx);
+   * boost::asio::ssl::stream<asio:ip::tcp::socket> sock(io_context, ctx);
    *
    * // ... establish connection and perform handshake ...
    *
@@ -158,18 +177,6 @@ class stream :
     return core_.engine_.native_handle();
   }
 
-  /// (Deprecated: Use native_handle().) Get the underlying implementation in
-  /// the native type.
-  /**
-   * This function may be used to obtain the underlying implementation of the
-   * context. This is intended to allow access to stream functionality that is
-   * not otherwise provided.
-   */
-  impl_type impl()
-  {
-    return &backwards_compatible_impl_;
-  }
-
   /// Get a reference to the next layer.
   /**
    * This function returns a reference to the next layer in a stack of stream
@@ -253,10 +260,11 @@ class stream :
    *
    * @note Calls @c SSL_set_verify.
    */
-  boost::system::error_code set_verify_mode(
+  BOOST_ASIO_SYNC_OP_VOID set_verify_mode(
       verify_mode v, boost::system::error_code& ec)
   {
-    return core_.engine_.set_verify_mode(v, ec);
+    core_.engine_.set_verify_mode(v, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Set the peer verification depth.
@@ -290,10 +298,11 @@ class stream :
    *
    * @note Calls @c SSL_set_verify_depth.
    */
-  boost::system::error_code set_verify_depth(
+  BOOST_ASIO_SYNC_OP_VOID set_verify_depth(
       int depth, boost::system::error_code& ec)
   {
-    return core_.engine_.set_verify_depth(depth, ec);
+    core_.engine_.set_verify_depth(depth, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Set the callback used to verify peer certificates.
@@ -341,11 +350,12 @@ class stream :
    * @note Calls @c SSL_set_verify.
    */
   template <typename VerifyCallback>
-  boost::system::error_code set_verify_callback(VerifyCallback callback,
+  BOOST_ASIO_SYNC_OP_VOID set_verify_callback(VerifyCallback callback,
       boost::system::error_code& ec)
   {
-    return core_.engine_.set_verify_callback(
+    core_.engine_.set_verify_callback(
         new detail::verify_callback<VerifyCallback>(callback), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform SSL handshaking.
@@ -375,11 +385,11 @@ class stream :
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code handshake(handshake_type type,
+  BOOST_ASIO_SYNC_OP_VOID handshake(handshake_type type,
       boost::system::error_code& ec)
   {
     detail::io(next_layer_, core_, detail::handshake_op(type), ec);
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform SSL handshaking.
@@ -415,12 +425,12 @@ class stream :
    * @param ec Set to indicate what error occurred, if any.
    */
   template <typename ConstBufferSequence>
-  boost::system::error_code handshake(handshake_type type,
+  BOOST_ASIO_SYNC_OP_VOID handshake(handshake_type type,
       const ConstBufferSequence& buffers, boost::system::error_code& ec)
   {
     detail::io(next_layer_, core_,
         detail::buffered_handshake_op<ConstBufferSequence>(type, buffers), ec);
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous SSL handshake.
@@ -448,12 +458,11 @@ class stream :
     // not meet the documented type requirements for a HandshakeHandler.
     BOOST_ASIO_HANDSHAKE_HANDLER_CHECK(HandshakeHandler, handler) type_check;
 
-    boost::asio::detail::async_result_init<
-      HandshakeHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(HandshakeHandler)(handler));
+    boost::asio::async_completion<HandshakeHandler,
+      void (boost::system::error_code)> init(handler);
 
     detail::async_io(next_layer_, core_,
-        detail::handshake_op(type), init.handler);
+        detail::handshake_op(type), init.completion_handler);
 
     return init.result.get();
   }
@@ -490,13 +499,12 @@ class stream :
     BOOST_ASIO_BUFFERED_HANDSHAKE_HANDLER_CHECK(
         BufferedHandshakeHandler, handler) type_check;
 
-    boost::asio::detail::async_result_init<BufferedHandshakeHandler,
-      void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(BufferedHandshakeHandler)(handler));
+    boost::asio::async_completion<BufferedHandshakeHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     detail::async_io(next_layer_, core_,
         detail::buffered_handshake_op<ConstBufferSequence>(type, buffers),
-        init.handler);
+        init.completion_handler);
 
     return init.result.get();
   }
@@ -522,10 +530,10 @@ class stream :
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code shutdown(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID shutdown(boost::system::error_code& ec)
   {
     detail::io(next_layer_, core_, detail::shutdown_op(), ec);
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Asynchronously shut down SSL on the stream.
@@ -549,11 +557,11 @@ class stream :
     // not meet the documented type requirements for a ShutdownHandler.
     BOOST_ASIO_SHUTDOWN_HANDLER_CHECK(ShutdownHandler, handler) type_check;
 
-    boost::asio::detail::async_result_init<
-      ShutdownHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(ShutdownHandler)(handler));
+    boost::asio::async_completion<ShutdownHandler,
+      void (boost::system::error_code)> init(handler);
 
-    detail::async_io(next_layer_, core_, detail::shutdown_op(), init.handler);
+    detail::async_io(next_layer_, core_, detail::shutdown_op(),
+        init.completion_handler);
 
     return init.result.get();
   }
@@ -639,12 +647,12 @@ class stream :
     // not meet the documented type requirements for a WriteHandler.
     BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
 
-    boost::asio::detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    boost::asio::async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     detail::async_io(next_layer_, core_,
-        detail::write_op<ConstBufferSequence>(buffers), init.handler);
+        detail::write_op<ConstBufferSequence>(buffers),
+        init.completion_handler);
 
     return init.result.get();
   }
@@ -731,12 +739,12 @@ class stream :
     // not meet the documented type requirements for a ReadHandler.
     BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
-    boost::asio::detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    boost::asio::async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
     detail::async_io(next_layer_, core_,
-        detail::read_op<MutableBufferSequence>(buffers), init.handler);
+        detail::read_op<MutableBufferSequence>(buffers),
+        init.completion_handler);
 
     return init.result.get();
   }
@@ -744,11 +752,8 @@ class stream :
 private:
   Stream next_layer_;
   detail::stream_core core_;
-  impl_struct backwards_compatible_impl_;
 };
 
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace ssl
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/ssl/stream_service.hpp b/include/boost/asio/ssl/stream_service.hpp
deleted file mode 100644
index 39e39f539c..0000000000
--- a/include/boost/asio/ssl/stream_service.hpp
+++ /dev/null
@@ -1,42 +0,0 @@
-//
-// ssl/stream_service.hpp
-// ~~~~~~~~~~~~~~~~~~~~~~
-//
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
-//
-// Distributed under the Boost Software License, Version 1.0. (See accompanying
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-//
-
-#ifndef BOOST_ASIO_SSL_STREAM_SERVICE_HPP
-#define BOOST_ASIO_SSL_STREAM_SERVICE_HPP
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1200)
-# pragma once
-#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
-#include <boost/asio/detail/config.hpp>
-
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/ssl/old/stream_service.hpp>
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-#include <boost/asio/detail/push_options.hpp>
-
-namespace boost {
-namespace asio {
-namespace ssl {
-
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-using boost::asio::ssl::old::stream_service;
-
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-} // namespace ssl
-} // namespace asio
-} // namespace boost
-
-#include <boost/asio/detail/pop_options.hpp>
-
-#endif // BOOST_ASIO_SSL_STREAM_SERVICE_HPP
diff --git a/include/boost/asio/ssl/verify_context.hpp b/include/boost/asio/ssl/verify_context.hpp
index 6b7a884e77..4daf0c7e23 100644
--- a/include/boost/asio/ssl/verify_context.hpp
+++ b/include/boost/asio/ssl/verify_context.hpp
@@ -17,10 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-# include <boost/asio/detail/noncopyable.hpp>
-# include <boost/asio/ssl/detail/openssl_types.hpp>
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/ssl/detail/openssl_types.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -28,8 +26,6 @@ namespace boost {
 namespace asio {
 namespace ssl {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 /// A simple wrapper around the X509_STORE_CTX type, used during verification of
 /// a peer certificate.
 /**
@@ -64,8 +60,6 @@ class verify_context
   native_handle_type handle_;
 };
 
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
 } // namespace ssl
 } // namespace asio
 } // namespace boost
diff --git a/include/boost/asio/steady_timer.hpp b/include/boost/asio/steady_timer.hpp
index f18ce399ae..af72adbf6e 100644
--- a/include/boost/asio/steady_timer.hpp
+++ b/include/boost/asio/steady_timer.hpp
@@ -17,22 +17,14 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_HAS_STD_CHRONO) \
-  || defined(BOOST_ASIO_HAS_BOOST_CHRONO) \
-  || defined(GENERATING_DOCUMENTATION)
-
-#if defined(BOOST_ASIO_HAS_STD_CHRONO)
-# include <chrono>
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-# include <boost/chrono/system_clocks.hpp>
-#endif
+#if defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
 
 #include <boost/asio/basic_waitable_timer.hpp>
+#include <boost/asio/detail/chrono.hpp>
 
 namespace boost {
 namespace asio {
 
-#if defined(GENERATING_DOCUMENTATION)
 /// Typedef for a timer based on the steady clock.
 /**
  * This typedef uses the C++11 @c &lt;chrono&gt; standard library facility, if
@@ -43,21 +35,10 @@ namespace asio {
  * @endcode
  */
 typedef basic_waitable_timer<chrono::steady_clock> steady_timer;
-#elif defined(BOOST_ASIO_HAS_STD_CHRONO)
-# if defined(BOOST_ASIO_HAS_STD_CHRONO_MONOTONIC_CLOCK)
-typedef basic_waitable_timer<std::chrono::monotonic_clock> steady_timer;
-# else // defined(BOOST_ASIO_HAS_STD_CHRONO_MONOTONIC_CLOCK)
-typedef basic_waitable_timer<std::chrono::steady_clock> steady_timer;
-# endif // defined(BOOST_ASIO_HAS_STD_CHRONO_MONOTONIC_CLOCK)
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-typedef basic_waitable_timer<boost::chrono::steady_clock> steady_timer;
-#endif
 
 } // namespace asio
 } // namespace boost
 
-#endif // defined(BOOST_ASIO_HAS_STD_CHRONO) 
-       //   || defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-       //   || defined(GENERATING_DOCUMENTATION)
+#endif // defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
 
 #endif // BOOST_ASIO_STEADY_TIMER_HPP
diff --git a/include/boost/asio/strand.hpp b/include/boost/asio/strand.hpp
index a4f3797e6a..9d0ad058f3 100644
--- a/include/boost/asio/strand.hpp
+++ b/include/boost/asio/strand.hpp
@@ -16,239 +16,273 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
-#include <boost/asio/async_result.hpp>
-#include <boost/asio/detail/handler_type_requirements.hpp>
-#include <boost/asio/detail/strand_service.hpp>
-#include <boost/asio/detail/wrapped_handler.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/detail/strand_executor_service.hpp>
+#include <boost/asio/detail/type_traits.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
-/// Provides serialised handler execution.
-/**
- * The io_service::strand class provides the ability to post and dispatch
- * handlers with the guarantee that none of those handlers will execute
- * concurrently.
- *
- * @par Order of handler invocation
- * Given:
- *
- * @li a strand object @c s
- *
- * @li an object @c a meeting completion handler requirements
- *
- * @li an object @c a1 which is an arbitrary copy of @c a made by the
- * implementation
- *
- * @li an object @c b meeting completion handler requirements
- *
- * @li an object @c b1 which is an arbitrary copy of @c b made by the
- * implementation
- *
- * if any of the following conditions are true:
- *
- * @li @c s.post(a) happens-before @c s.post(b)
- * 
- * @li @c s.post(a) happens-before @c s.dispatch(b), where the latter is
- * performed outside the strand
- * 
- * @li @c s.dispatch(a) happens-before @c s.post(b), where the former is
- * performed outside the strand
- * 
- * @li @c s.dispatch(a) happens-before @c s.dispatch(b), where both are
- * performed outside the strand
- *   
- * then @c asio_handler_invoke(a1, &a1) happens-before
- * @c asio_handler_invoke(b1, &b1).
- * 
- * Note that in the following case:
- * @code async_op_1(..., s.wrap(a));
- * async_op_2(..., s.wrap(b)); @endcode
- * the completion of the first async operation will perform @c s.dispatch(a),
- * and the second will perform @c s.dispatch(b), but the order in which those
- * are performed is unspecified. That is, you cannot state whether one
- * happens-before the other. Therefore none of the above conditions are met and
- * no ordering guarantee is made.
- *
- * @note The implementation makes no guarantee that handlers posted or
- * dispatched through different @c strand objects will be invoked concurrently.
- *
- * @par Thread Safety
- * @e Distinct @e objects: Safe.@n
- * @e Shared @e objects: Safe.
- *
- * @par Concepts:
- * Dispatcher.
- */
-class io_service::strand
+/// Provides serialised function invocation for any executor type.
+template <typename Executor>
+class strand
 {
 public:
-  /// Constructor.
+  /// The type of the underlying executor.
+  typedef Executor inner_executor_type;
+
+  /// Default constructor.
   /**
-   * Constructs the strand.
-   *
-   * @param io_service The io_service object that the strand will use to
-   * dispatch handlers that are ready to be run.
+   * This constructor is only valid if the underlying executor type is default
+   * constructible.
    */
-  explicit strand(boost::asio::io_service& io_service)
-    : service_(boost::asio::use_service<
-        boost::asio::detail::strand_service>(io_service))
+  strand()
+    : executor_(),
+      impl_(use_service<detail::strand_executor_service>(
+            executor_.context()).create_implementation())
   {
-    service_.construct(impl_);
   }
 
-  /// Destructor.
+  /// Construct a strand for the specified executor.
+  explicit strand(const Executor& e)
+    : executor_(e),
+      impl_(use_service<detail::strand_executor_service>(
+            executor_.context()).create_implementation())
+  {
+  }
+
+  /// Copy constructor.
+  strand(const strand& other) BOOST_ASIO_NOEXCEPT
+    : executor_(other.executor_),
+      impl_(other.impl_)
+  {
+  }
+
+  /// Converting constructor.
   /**
-   * Destroys a strand.
-   *
-   * Handlers posted through the strand that have not yet been invoked will
-   * still be dispatched in a way that meets the guarantee of non-concurrency.
+   * This constructor is only valid if the @c OtherExecutor type is convertible
+   * to @c Executor.
    */
-  ~strand()
+  template <class OtherExecutor>
+  strand(
+      const strand<OtherExecutor>& other) BOOST_ASIO_NOEXCEPT
+    : executor_(other.executor_),
+      impl_(other.impl_)
+  {
+  }
+
+  /// Assignment operator.
+  strand& operator=(const strand& other) BOOST_ASIO_NOEXCEPT
   {
+    executor_ = other.executor_;
+    impl_ = other.impl_;
+    return *this;
   }
 
-  /// Get the io_service associated with the strand.
+  /// Converting assignment operator.
   /**
-   * This function may be used to obtain the io_service object that the strand
-   * uses to dispatch handlers for asynchronous operations.
-   *
-   * @return A reference to the io_service object that the strand will use to
-   * dispatch handlers. Ownership is not transferred to the caller.
+   * This assignment operator is only valid if the @c OtherExecutor type is
+   * convertible to @c Executor.
    */
-  boost::asio::io_service& get_io_service()
+  template <class OtherExecutor>
+  strand& operator=(
+      const strand<OtherExecutor>& other) BOOST_ASIO_NOEXCEPT
+  {
+    executor_ = other.executor_;
+    impl_ = other.impl_;
+    return *this;
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move constructor.
+  strand(strand&& other) BOOST_ASIO_NOEXCEPT
+    : executor_(BOOST_ASIO_MOVE_CAST(Executor)(other.executor_)),
+      impl_(BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_))
   {
-    return service_.get_io_service();
   }
 
-  /// Request the strand to invoke the given handler.
+  /// Converting move constructor.
   /**
-   * This function is used to ask the strand to execute the given handler.
-   *
-   * The strand object guarantees that handlers posted or dispatched through
-   * the strand will not be executed concurrently. The handler may be executed
-   * inside this function if the guarantee can be met. If this function is
-   * called from within a handler that was posted or dispatched through the same
-   * strand, then the new handler will be executed immediately.
-   *
-   * The strand's guarantee is in addition to the guarantee provided by the
-   * underlying io_service. The io_service guarantees that the handler will only
-   * be called in a thread in which the io_service's run member function is
-   * currently being invoked.
-   *
-   * @param handler The handler to be called. The strand will make a copy of the
-   * handler object as required. The function signature of the handler must be:
-   * @code void handler(); @endcode
+   * This constructor is only valid if the @c OtherExecutor type is convertible
+   * to @c Executor.
    */
-  template <typename CompletionHandler>
-  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
-  dispatch(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
+  template <class OtherExecutor>
+  strand(strand<OtherExecutor>&& other) BOOST_ASIO_NOEXCEPT
+    : executor_(BOOST_ASIO_MOVE_CAST(OtherExecutor)(other)),
+      impl_(BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_))
   {
-    // If you get an error on the following line it means that your handler does
-    // not meet the documented type requirements for a CompletionHandler.
-    BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
+  }
 
-    detail::async_result_init<
-      CompletionHandler, void ()> init(
-        BOOST_ASIO_MOVE_CAST(CompletionHandler)(handler));
+  /// Move assignment operator.
+  strand& operator=(strand&& other) BOOST_ASIO_NOEXCEPT
+  {
+    executor_ = BOOST_ASIO_MOVE_CAST(Executor)(other);
+    impl_ = BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_);
+    return *this;
+  }
 
-    service_.dispatch(impl_, init.handler);
+  /// Converting move assignment operator.
+  /**
+   * This assignment operator is only valid if the @c OtherExecutor type is
+   * convertible to @c Executor.
+   */
+  template <class OtherExecutor>
+  strand& operator=(
+      const strand<OtherExecutor>&& other) BOOST_ASIO_NOEXCEPT
+  {
+    executor_ = BOOST_ASIO_MOVE_CAST(OtherExecutor)(other);
+    impl_ = BOOST_ASIO_MOVE_CAST(implementation_type)(other.impl_);
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Destructor.
+  ~strand()
+  {
+  }
 
-    return init.result.get();
+  /// Obtain the underlying executor.
+  inner_executor_type get_inner_executor() const BOOST_ASIO_NOEXCEPT
+  {
+    return executor_;
   }
 
-  /// Request the strand to invoke the given handler and return
-  /// immediately.
+  /// Obtain the underlying execution context.
+  execution_context& context() const BOOST_ASIO_NOEXCEPT
+  {
+    return executor_.context();
+  }
+
+  /// Inform the strand that it has some outstanding work to do.
   /**
-   * This function is used to ask the strand to execute the given handler, but
-   * without allowing the strand to call the handler from inside this function.
-   *
-   * The strand object guarantees that handlers posted or dispatched through
-   * the strand will not be executed concurrently. The strand's guarantee is in
-   * addition to the guarantee provided by the underlying io_service. The
-   * io_service guarantees that the handler will only be called in a thread in
-   * which the io_service's run member function is currently being invoked.
-   *
-   * @param handler The handler to be called. The strand will make a copy of the
-   * handler object as required. The function signature of the handler must be:
-   * @code void handler(); @endcode
+   * The strand delegates this call to its underlying executor.
    */
-  template <typename CompletionHandler>
-  BOOST_ASIO_INITFN_RESULT_TYPE(CompletionHandler, void ())
-  post(BOOST_ASIO_MOVE_ARG(CompletionHandler) handler)
+  void on_work_started() const BOOST_ASIO_NOEXCEPT
   {
-    // If you get an error on the following line it means that your handler does
-    // not meet the documented type requirements for a CompletionHandler.
-    BOOST_ASIO_COMPLETION_HANDLER_CHECK(CompletionHandler, handler) type_check;
+    executor_.on_work_started();
+  }
 
-    detail::async_result_init<
-      CompletionHandler, void ()> init(
-        BOOST_ASIO_MOVE_CAST(CompletionHandler)(handler));
+  /// Inform the strand that some work is no longer outstanding.
+  /**
+   * The strand delegates this call to its underlying executor.
+   */
+  void on_work_finished() const BOOST_ASIO_NOEXCEPT
+  {
+    executor_.on_work_finished();
+  }
 
-    service_.post(impl_, init.handler);
+  /// Request the strand to invoke the given function object.
+  /**
+   * This function is used to ask the strand to execute the given function
+   * object on its underlying executor. The function object will be executed
+   * inside this function if the strand is not otherwise busy and if the
+   * underlying executor's @c dispatch() function is also able to execute the
+   * function before returning.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+  {
+    detail::strand_executor_service::dispatch(impl_,
+        executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
+  }
 
-    return init.result.get();
+  /// Request the strand to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object will never be executed inside this function.
+   * Instead, it will be scheduled by the underlying executor's defer function.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
+  {
+    detail::strand_executor_service::post(impl_,
+        executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
   }
 
-  /// Create a new handler that automatically dispatches the wrapped handler
-  /// on the strand.
+  /// Request the strand to invoke the given function object.
   /**
-   * This function is used to create a new handler function object that, when
-   * invoked, will automatically pass the wrapped handler to the strand's
-   * dispatch function.
+   * This function is used to ask the executor to execute the given function
+   * object. The function object will never be executed inside this function.
+   * Instead, it will be scheduled by the underlying executor's defer function.
    *
-   * @param handler The handler to be wrapped. The strand will make a copy of
-   * the handler object as required. The function signature of the handler must
-   * be: @code void handler(A1 a1, ... An an); @endcode
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
    *
-   * @return A function object that, when invoked, passes the wrapped handler to
-   * the strand's dispatch function. Given a function object with the signature:
-   * @code R f(A1 a1, ... An an); @endcode
-   * If this function object is passed to the wrap function like so:
-   * @code strand.wrap(f); @endcode
-   * then the return value is a function object with the signature
-   * @code void g(A1 a1, ... An an); @endcode
-   * that, when invoked, executes code equivalent to:
-   * @code strand.dispatch(boost::bind(f, a1, ... an)); @endcode
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
    */
-  template <typename Handler>
-#if defined(GENERATING_DOCUMENTATION)
-  unspecified
-#else
-  detail::wrapped_handler<strand, Handler, detail::is_continuation_if_running>
-#endif
-  wrap(Handler handler)
+  template <typename Function, typename Allocator>
+  void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const
   {
-    return detail::wrapped_handler<io_service::strand, Handler,
-        detail::is_continuation_if_running>(*this, handler);
+    detail::strand_executor_service::defer(impl_,
+        executor_, BOOST_ASIO_MOVE_CAST(Function)(f), a);
   }
 
   /// Determine whether the strand is running in the current thread.
   /**
-   * @return @c true if the current thread is executing a handler that was
-   * submitted to the strand using post(), dispatch() or wrap(). Otherwise
+   * @return @c true if the current thread is executing a function that was
+   * submitted to the strand using post(), dispatch() or defer(). Otherwise
    * returns @c false.
    */
-  bool running_in_this_thread() const
+  bool running_in_this_thread() const BOOST_ASIO_NOEXCEPT
+  {
+    return detail::strand_executor_service::running_in_this_thread(impl_);
+  }
+
+  /// Compare two strands for equality.
+  /**
+   * Two strands are equal if they refer to the same ordered, non-concurrent
+   * state.
+   */
+  friend bool operator==(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
+  {
+    return a.impl_ == b.impl_;
+  }
+
+  /// Compare two strands for inequality.
+  /**
+   * Two strands are equal if they refer to the same ordered, non-concurrent
+   * state.
+   */
+  friend bool operator!=(const strand& a, const strand& b) BOOST_ASIO_NOEXCEPT
   {
-    return service_.running_in_this_thread(impl_);
+    return a.impl_ != b.impl_;
   }
 
 private:
-  boost::asio::detail::strand_service& service_;
-  boost::asio::detail::strand_service::implementation_type impl_;
+  Executor executor_;
+  typedef detail::strand_executor_service::implementation_type
+    implementation_type;
+  implementation_type impl_;
 };
 
-/// (Deprecated: Use boost::asio::io_service::strand.) Typedef for backwards
-/// compatibility.
-typedef boost::asio::io_service::strand strand;
-
 } // namespace asio
 } // namespace boost
 
 #include <boost/asio/detail/pop_options.hpp>
 
+// If both io_context.hpp and strand.hpp have been included, automatically
+// include the header file needed for the io_context::strand class.
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+# if defined(BOOST_ASIO_IO_CONTEXT_HPP)
+#  include <boost/asio/io_context_strand.hpp>
+# endif // defined(BOOST_ASIO_IO_CONTEXT_HPP)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 #endif // BOOST_ASIO_STRAND_HPP
diff --git a/include/boost/asio/stream_socket_service.hpp b/include/boost/asio/stream_socket_service.hpp
index 09463f4718..534ce6528b 100644
--- a/include/boost/asio/stream_socket_service.hpp
+++ b/include/boost/asio/stream_socket_service.hpp
@@ -16,11 +16,14 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/winrt_ssocket_service.hpp>
@@ -39,7 +42,7 @@ namespace asio {
 template <typename Protocol>
 class stream_socket_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<stream_socket_service<Protocol> >
 #endif
@@ -47,7 +50,7 @@ class stream_socket_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The protocol type.
@@ -74,13 +77,6 @@ class stream_socket_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native socket type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef typename service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native socket type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -88,11 +84,11 @@ class stream_socket_service
   typedef typename service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new stream socket service for the specified io_service.
-  explicit stream_socket_service(boost::asio::io_service& io_service)
+  /// Construct a new stream socket service for the specified io_context.
+  explicit stream_socket_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        stream_socket_service<Protocol> >(io_service),
-      service_impl_(io_service)
+        stream_socket_service<Protocol> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -143,22 +139,23 @@ class stream_socket_service
   }
 
   /// Open a stream socket.
-  boost::system::error_code open(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID open(implementation_type& impl,
       const protocol_type& protocol, boost::system::error_code& ec)
   {
     if (protocol.type() == BOOST_ASIO_OS_DEF(SOCK_STREAM))
       service_impl_.open(impl, protocol, ec);
     else
       ec = boost::asio::error::invalid_argument;
-    return ec;
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Assign an existing native socket to a stream socket.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const protocol_type& protocol, const native_handle_type& native_socket,
       boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, protocol, native_socket, ec);
+    service_impl_.assign(impl, protocol, native_socket, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is open.
@@ -168,16 +165,18 @@ class stream_socket_service
   }
 
   /// Close a stream socket implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
-  /// (Deprecated: Use native_handle().) Get the native socket implementation.
-  native_type native(implementation_type& impl)
+  /// Release ownership of the underlying socket.
+  native_handle_type release(implementation_type& impl,
+      boost::system::error_code& ec)
   {
-    return service_impl_.native_handle(impl);
+    return service_impl_.release(impl, ec);
   }
 
   /// Get the native socket implementation.
@@ -187,10 +186,11 @@ class stream_socket_service
   }
 
   /// Cancel all asynchronous operations associated with the socket.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the socket is at the out-of-band data mark.
@@ -208,17 +208,19 @@ class stream_socket_service
   }
 
   /// Bind the stream socket to the specified local endpoint.
-  boost::system::error_code bind(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID bind(implementation_type& impl,
       const endpoint_type& endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.bind(impl, endpoint, ec);
+    service_impl_.bind(impl, endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Connect the stream socket to the specified endpoint.
-  boost::system::error_code connect(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID connect(implementation_type& impl,
       const endpoint_type& peer_endpoint, boost::system::error_code& ec)
   {
-    return service_impl_.connect(impl, peer_endpoint, ec);
+    service_impl_.connect(impl, peer_endpoint, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous connect.
@@ -229,37 +231,39 @@ class stream_socket_service
       const endpoint_type& peer_endpoint,
       BOOST_ASIO_MOVE_ARG(ConnectHandler) handler)
   {
-    detail::async_result_init<
-      ConnectHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(ConnectHandler)(handler));
+    async_completion<ConnectHandler,
+      void (boost::system::error_code)> init(handler);
 
-    service_impl_.async_connect(impl, peer_endpoint, init.handler);
+    service_impl_.async_connect(impl, peer_endpoint, init.completion_handler);
 
     return init.result.get();
   }
 
   /// Set a socket option.
   template <typename SettableSocketOption>
-  boost::system::error_code set_option(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID set_option(implementation_type& impl,
       const SettableSocketOption& option, boost::system::error_code& ec)
   {
-    return service_impl_.set_option(impl, option, ec);
+    service_impl_.set_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get a socket option.
   template <typename GettableSocketOption>
-  boost::system::error_code get_option(const implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID get_option(const implementation_type& impl,
       GettableSocketOption& option, boost::system::error_code& ec) const
   {
-    return service_impl_.get_option(impl, option, ec);
+    service_impl_.get_option(impl, option, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Perform an IO control command on the socket.
   template <typename IoControlCommand>
-  boost::system::error_code io_control(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID io_control(implementation_type& impl,
       IoControlCommand& command, boost::system::error_code& ec)
   {
-    return service_impl_.io_control(impl, command, ec);
+    service_impl_.io_control(impl, command, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the socket.
@@ -269,10 +273,11 @@ class stream_socket_service
   }
 
   /// Sets the non-blocking mode of the socket.
-  boost::system::error_code non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.non_blocking(impl, mode, ec);
+    service_impl_.non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Gets the non-blocking mode of the native socket implementation.
@@ -282,10 +287,11 @@ class stream_socket_service
   }
 
   /// Sets the non-blocking mode of the native socket implementation.
-  boost::system::error_code native_non_blocking(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID native_non_blocking(implementation_type& impl,
       bool mode, boost::system::error_code& ec)
   {
-    return service_impl_.native_non_blocking(impl, mode, ec);
+    service_impl_.native_non_blocking(impl, mode, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the local endpoint.
@@ -303,10 +309,36 @@ class stream_socket_service
   }
 
   /// Disable sends or receives on the socket.
-  boost::system::error_code shutdown(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID shutdown(implementation_type& impl,
       socket_base::shutdown_type what, boost::system::error_code& ec)
   {
-    return service_impl_.shutdown(impl, what, ec);
+    service_impl_.shutdown(impl, what, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Wait for the socket to become ready to read, ready to write, or to have
+  /// pending error conditions.
+  BOOST_ASIO_SYNC_OP_VOID wait(implementation_type& impl,
+      socket_base::wait_type w, boost::system::error_code& ec)
+  {
+    service_impl_.wait(impl, w, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Asynchronously wait for the socket to become ready to read, ready to
+  /// write, or to have pending error conditions.
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(implementation_type& impl, socket_base::wait_type w,
+      BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    service_impl_.async_wait(impl, w, init.completion_handler);
+
+    return init.result.get();
   }
 
   /// Send the given data to the peer.
@@ -327,11 +359,10 @@ class stream_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_send(impl, buffers, flags, init.handler);
+    service_impl_.async_send(impl, buffers, flags, init.completion_handler);
 
     return init.result.get();
   }
@@ -354,20 +385,19 @@ class stream_socket_service
       socket_base::message_flags flags,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_receive(impl, buffers, flags, init.handler);
+    service_impl_.async_receive(impl, buffers, flags, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -379,4 +409,6 @@ class stream_socket_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_STREAM_SOCKET_SERVICE_HPP
diff --git a/include/boost/asio/system_context.hpp b/include/boost/asio/system_context.hpp
new file mode 100644
index 0000000000..a630c3d961
--- /dev/null
+++ b/include/boost/asio/system_context.hpp
@@ -0,0 +1,81 @@
+//
+// system_context.hpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_SYSTEM_CONTEXT_HPP
+#define BOOST_ASIO_SYSTEM_CONTEXT_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/scheduler.hpp>
+#include <boost/asio/detail/thread_group.hpp>
+#include <boost/asio/execution_context.hpp>
+#include <boost/asio/system_executor.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// The executor context for the system executor.
+class system_context : public execution_context
+{
+public:
+  /// The executor type associated with the context.
+  typedef system_executor executor_type;
+
+  /// Destructor shuts down all threads in the system thread pool.
+  BOOST_ASIO_DECL ~system_context();
+
+  /// Obtain an executor for the context.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return system_executor();
+  }
+
+  /// Signal all threads in the system thread pool to stop.
+  BOOST_ASIO_DECL void stop();
+
+  /// Determine whether the system thread pool has been stopped.
+  BOOST_ASIO_DECL bool stopped() const BOOST_ASIO_NOEXCEPT;
+
+  /// Join all threads in the system thread pool.
+  BOOST_ASIO_DECL void join();
+
+#if defined(GENERATING_DOCUMENTATION)
+private:
+#endif // defined(GENERATING_DOCUMENTATION)
+  // Constructor creates all threads in the system thread pool.
+  BOOST_ASIO_DECL system_context();
+
+private:
+  friend class system_executor;
+
+  struct thread_function;
+
+  // The underlying scheduler.
+  detail::scheduler& scheduler_;
+
+  // The threads in the system thread pool.
+  detail::thread_group threads_;
+};
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/impl/system_context.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+#endif // BOOST_ASIO_SYSTEM_CONTEXT_HPP
diff --git a/include/boost/asio/system_executor.hpp b/include/boost/asio/system_executor.hpp
new file mode 100644
index 0000000000..0d8eb0a535
--- /dev/null
+++ b/include/boost/asio/system_executor.hpp
@@ -0,0 +1,131 @@
+//
+// system_executor.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_SYSTEM_EXECUTOR_HPP
+#define BOOST_ASIO_SYSTEM_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+class system_context;
+
+/// An executor that uses arbitrary threads.
+/**
+ * The system executor represents an execution context where functions are
+ * permitted to run on arbitrary threads. The post() and defer() functions
+ * schedule the function to run on an unspecified system thread pool, and
+ * dispatch() invokes the function immediately.
+ */
+class system_executor
+{
+public:
+  /// Obtain the underlying execution context.
+  system_context& context() const BOOST_ASIO_NOEXCEPT;
+
+  /// Inform the executor that it has some outstanding work to do.
+  /**
+   * For the system executor, this is a no-op.
+   */
+  void on_work_started() const BOOST_ASIO_NOEXCEPT
+  {
+  }
+
+  /// Inform the executor that some work is no longer outstanding.
+  /**
+   * For the system executor, this is a no-op.
+   */
+  void on_work_finished() const BOOST_ASIO_NOEXCEPT
+  {
+  }
+
+  /// Request the system executor to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object will always be executed inside this function.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the system executor to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object will never be executed inside this function.
+   * Instead, it will be scheduled to run on an unspecified system thread pool.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the system executor to invoke the given function object.
+  /**
+   * This function is used to ask the executor to execute the given function
+   * object. The function object will never be executed inside this function.
+   * Instead, it will be scheduled to run on an unspecified system thread pool.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Compare two executors for equality.
+  /**
+   * System executors always compare equal.
+   */
+  friend bool operator==(const system_executor&,
+      const system_executor&) BOOST_ASIO_NOEXCEPT
+  {
+    return true;
+  }
+
+  /// Compare two executors for inequality.
+  /**
+   * System executors always compare equal.
+   */
+  friend bool operator!=(const system_executor&,
+      const system_executor&) BOOST_ASIO_NOEXCEPT
+  {
+    return false;
+  }
+};
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/system_executor.hpp>
+
+#endif // BOOST_ASIO_SYSTEM_EXECUTOR_HPP
diff --git a/include/boost/asio/system_timer.hpp b/include/boost/asio/system_timer.hpp
index e95370dbbc..95c04409b5 100644
--- a/include/boost/asio/system_timer.hpp
+++ b/include/boost/asio/system_timer.hpp
@@ -17,22 +17,14 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_HAS_STD_CHRONO) \
-  || defined(BOOST_ASIO_HAS_BOOST_CHRONO) \
-  || defined(GENERATING_DOCUMENTATION)
-
-#if defined(BOOST_ASIO_HAS_STD_CHRONO)
-# include <chrono>
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-# include <boost/chrono/system_clocks.hpp>
-#endif
+#if defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
 
 #include <boost/asio/basic_waitable_timer.hpp>
+#include <boost/asio/detail/chrono.hpp>
 
 namespace boost {
 namespace asio {
 
-#if defined(GENERATING_DOCUMENTATION)
 /// Typedef for a timer based on the system clock.
 /**
  * This typedef uses the C++11 @c &lt;chrono&gt; standard library facility, if
@@ -43,17 +35,10 @@ namespace asio {
  * @endcode
  */
 typedef basic_waitable_timer<chrono::system_clock> system_timer;
-#elif defined(BOOST_ASIO_HAS_STD_CHRONO)
-typedef basic_waitable_timer<std::chrono::system_clock> system_timer;
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-typedef basic_waitable_timer<boost::chrono::system_clock> system_timer;
-#endif
 
 } // namespace asio
 } // namespace boost
 
-#endif // defined(BOOST_ASIO_HAS_STD_CHRONO) 
-       //   || defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-       //   || defined(GENERATING_DOCUMENTATION)
+#endif // defined(BOOST_ASIO_HAS_CHRONO) || defined(GENERATING_DOCUMENTATION)
 
 #endif // BOOST_ASIO_SYSTEM_TIMER_HPP
diff --git a/include/boost/asio/thread_pool.hpp b/include/boost/asio/thread_pool.hpp
new file mode 100644
index 0000000000..014cd1f99b
--- /dev/null
+++ b/include/boost/asio/thread_pool.hpp
@@ -0,0 +1,204 @@
+//
+// thread_pool.hpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_THREAD_POOL_HPP
+#define BOOST_ASIO_THREAD_POOL_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/noncopyable.hpp>
+#include <boost/asio/detail/scheduler.hpp>
+#include <boost/asio/detail/thread_group.hpp>
+#include <boost/asio/execution_context.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// A simple fixed-size thread pool.
+/**
+ * The thread pool class is an execution context where functions are permitted
+ * to run on one of a fixed number of threads.
+ */
+class thread_pool
+  : public execution_context
+{
+public:
+  class executor_type;
+
+  /// Constructs a pool with an automatically determined number of threads.
+  BOOST_ASIO_DECL thread_pool();
+
+  /// Constructs a pool with a specified number of threads.
+  BOOST_ASIO_DECL thread_pool(std::size_t num_threads);
+
+  /// Destructor.
+  /**
+   * Automatically stops and joins the pool, if not explicitly done beforehand.
+   */
+  BOOST_ASIO_DECL ~thread_pool();
+
+  /// Obtains the executor associated with the pool.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT;
+
+  /// Stops the threads.
+  /**
+   * This function stops the threads as soon as possible. As a result of calling
+   * @c stop(), pending function objects may be never be invoked.
+   */
+  BOOST_ASIO_DECL void stop();
+
+  /// Joins the threads.
+  /**
+   * This function blocks until the threads in the pool have completed. If @c
+   * stop() is not called prior to @c join(), the @c join() call will wait
+   * until the pool has no more outstanding work.
+   */
+  BOOST_ASIO_DECL void join();
+
+private:
+  friend class executor_type;
+  struct thread_function;
+
+  // The underlying scheduler.
+  detail::scheduler& scheduler_;
+
+  // The threads in the pool.
+  detail::thread_group threads_;
+};
+
+/// Executor used to submit functions to a thread pool.
+class thread_pool::executor_type
+{
+public:
+  /// Obtain the underlying execution context.
+  thread_pool& context() const BOOST_ASIO_NOEXCEPT;
+
+  /// Inform the thread pool that it has some outstanding work to do.
+  /**
+   * This function is used to inform the thread pool that some work has begun.
+   * This ensures that the thread pool's join() function will not return while
+   * the work is underway.
+   */
+  void on_work_started() const BOOST_ASIO_NOEXCEPT;
+
+  /// Inform the thread pool that some work is no longer outstanding.
+  /**
+   * This function is used to inform the thread pool that some work has
+   * finished. Once the count of unfinished work reaches zero, the thread
+   * pool's join() function is permitted to exit.
+   */
+  void on_work_finished() const BOOST_ASIO_NOEXCEPT;
+
+  /// Request the thread pool to invoke the given function object.
+  /**
+   * This function is used to ask the thread pool to execute the given function
+   * object. If the current thread belongs to the pool, @c dispatch() executes
+   * the function before returning. Otherwise, the function will be scheduled
+   * to run on the thread pool.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void dispatch(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the thread pool to invoke the given function object.
+  /**
+   * This function is used to ask the thread pool to execute the given function
+   * object. The function object will never be executed inside @c post().
+   * Instead, it will be scheduled to run on the thread pool.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void post(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Request the thread pool to invoke the given function object.
+  /**
+   * This function is used to ask the thread pool to execute the given function
+   * object. The function object will never be executed inside @c defer().
+   * Instead, it will be scheduled to run on the thread pool.
+   *
+   * If the current thread belongs to the thread pool, @c defer() will delay
+   * scheduling the function object until the current thread returns control to
+   * the pool.
+   *
+   * @param f The function object to be called. The executor will make
+   * a copy of the handler object as required. The function signature of the
+   * function object must be: @code void function(); @endcode
+   *
+   * @param a An allocator that may be used by the executor to allocate the
+   * internal storage needed for function invocation.
+   */
+  template <typename Function, typename Allocator>
+  void defer(BOOST_ASIO_MOVE_ARG(Function) f, const Allocator& a) const;
+
+  /// Determine whether the thread pool is running in the current thread.
+  /**
+   * @return @c true if the current thread belongs to the pool. Otherwise
+   * returns @c false.
+   */
+  bool running_in_this_thread() const BOOST_ASIO_NOEXCEPT;
+
+  /// Compare two executors for equality.
+  /**
+   * Two executors are equal if they refer to the same underlying thread pool.
+   */
+  friend bool operator==(const executor_type& a,
+      const executor_type& b) BOOST_ASIO_NOEXCEPT
+  {
+    return &a.pool_ == &b.pool_;
+  }
+
+  /// Compare two executors for inequality.
+  /**
+   * Two executors are equal if they refer to the same underlying thread pool.
+   */
+  friend bool operator!=(const executor_type& a,
+      const executor_type& b) BOOST_ASIO_NOEXCEPT
+  {
+    return &a.pool_ != &b.pool_;
+  }
+
+private:
+  friend class thread_pool;
+
+  // Constructor.
+  explicit executor_type(thread_pool& p) : pool_(p) {}
+
+  // The underlying thread pool.
+  thread_pool& pool_;
+};
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#include <boost/asio/impl/thread_pool.hpp>
+#if defined(BOOST_ASIO_HEADER_ONLY)
+# include <boost/asio/impl/thread_pool.ipp>
+#endif // defined(BOOST_ASIO_HEADER_ONLY)
+
+#endif // BOOST_ASIO_THREAD_POOL_HPP
diff --git a/include/boost/asio/use_future.hpp b/include/boost/asio/use_future.hpp
index e4ce7f7975..68df9a9e95 100644
--- a/include/boost/asio/use_future.hpp
+++ b/include/boost/asio/use_future.hpp
@@ -16,12 +16,26 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_HAS_STD_FUTURE) \
+  || defined(GENERATING_DOCUMENTATION)
+
 #include <memory>
+#include <boost/asio/detail/type_traits.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
+namespace detail {
+
+template <typename Function, typename Allocator>
+class packaged_token;
+
+template <typename Function, typename Allocator, typename Result>
+class packaged_handler;
+
+} // namespace detail
 
 /// Class used to specify that an asynchronous operation should return a future.
 /**
@@ -57,12 +71,21 @@ class use_future_t
   {
   }
 
-  /// Specify an alternate allocator.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use rebind().) Specify an alternate allocator.
   template <typename OtherAllocator>
   use_future_t<OtherAllocator> operator[](const OtherAllocator& allocator) const
   {
     return use_future_t<OtherAllocator>(allocator);
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Specify an alternate allocator.
+  template <typename OtherAllocator>
+  use_future_t<OtherAllocator> rebind(const OtherAllocator& allocator) const
+  {
+    return use_future_t<OtherAllocator>(allocator);
+  }
 
   /// Obtain allocator.
   allocator_type get_allocator() const
@@ -70,6 +93,31 @@ class use_future_t
     return allocator_;
   }
 
+  /// Wrap a function object in a packaged task.
+  /**
+   * The @c package function is used to adapt a function object as a packaged
+   * task. When this adapter is passed as a completion token to an asynchronous
+   * operation, the result of the function object is retuned via a std::future.
+   *
+   * @par Example
+   *
+   * @code std::future<std::size_t> fut =
+   *   my_socket.async_read_some(buffer,
+   *     use_future([](boost::system::error_code ec, std::size_t n)
+   *       {
+   *         return ec ? 0 : n;
+   *       }));
+   * ...
+   * std::size_t n = fut.get(); @endcode
+   */
+  template <typename Function>
+#if defined(GENERATING_DOCUMENTATION)
+  unspecified
+#else // defined(GENERATING_DOCUMENTATION)
+  detail::packaged_token<typename decay<Function>::type, Allocator>
+#endif // defined(GENERATING_DOCUMENTATION)
+  operator()(BOOST_ASIO_MOVE_ARG(Function) f) const;
+
 private:
   Allocator allocator_;
 };
@@ -91,4 +139,7 @@ constexpr use_future_t<> use_future;
 
 #include <boost/asio/impl/use_future.hpp>
 
+#endif // defined(BOOST_ASIO_HAS_STD_FUTURE)
+       //   || defined(GENERATING_DOCUMENTATION)
+
 #endif // BOOST_ASIO_USE_FUTURE_HPP
diff --git a/include/boost/asio/uses_executor.hpp b/include/boost/asio/uses_executor.hpp
new file mode 100644
index 0000000000..0951a86a2d
--- /dev/null
+++ b/include/boost/asio/uses_executor.hpp
@@ -0,0 +1,73 @@
+//
+// uses_executor.hpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_USES_EXECUTOR_HPP
+#define BOOST_ASIO_USES_EXECUTOR_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/detail/type_traits.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+
+/// A special type, similar to std::nothrow_t, used to disambiguate
+/// constructors that accept executor arguments.
+/**
+ * The executor_arg_t struct is an empty structure type used as a unique type
+ * to disambiguate constructor and function overloading. Specifically, some
+ * types have constructors with executor_arg_t as the first argument,
+ * immediately followed by an argument of a type that satisfies the Executor
+ * type requirements.
+ */
+struct executor_arg_t
+{
+  /// Constructor.
+  BOOST_ASIO_CONSTEXPR executor_arg_t() BOOST_ASIO_NOEXCEPT
+  {
+  }
+};
+
+/// A special value, similar to std::nothrow, used to disambiguate constructors
+/// that accept executor arguments.
+/**
+ * See boost::asio::executor_arg_t and boost::asio::uses_executor
+ * for more information.
+ */
+#if defined(BOOST_ASIO_HAS_CONSTEXPR) || defined(GENERATING_DOCUMENTATION)
+constexpr executor_arg_t executor_arg;
+#elif defined(BOOST_ASIO_MSVC)
+__declspec(selectany) executor_arg_t executor_arg;
+#endif
+
+/// The uses_executor trait detects whether a type T has an associated executor
+/// that is convertible from type Executor.
+/**
+ * Meets the BinaryTypeTrait requirements. The Asio library provides a
+ * definition that is derived from false_type. A program may specialize this
+ * template to derive from true_type for a user-defined type T that can be
+ * constructed with an executor, where the first argument of a constructor has
+ * type executor_arg_t and the second argument is convertible from type
+ * Executor.
+ */
+template <typename T, typename Executor>
+struct uses_executor : false_type {};
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_USES_EXECUTOR_HPP
diff --git a/include/boost/asio/version.hpp b/include/boost/asio/version.hpp
index 76b6440b01..98fab16124 100644
--- a/include/boost/asio/version.hpp
+++ b/include/boost/asio/version.hpp
@@ -18,6 +18,6 @@
 // BOOST_ASIO_VERSION % 100 is the sub-minor version
 // BOOST_ASIO_VERSION / 100 % 1000 is the minor version
 // BOOST_ASIO_VERSION / 100000 is the major version
-#define BOOST_ASIO_VERSION 101010 // 1.10.10
+#define BOOST_ASIO_VERSION 101100 // 1.11.0
 
 #endif // BOOST_ASIO_VERSION_HPP
diff --git a/include/boost/asio/wait_traits.hpp b/include/boost/asio/wait_traits.hpp
index f1a3c18243..76b8593c34 100644
--- a/include/boost/asio/wait_traits.hpp
+++ b/include/boost/asio/wait_traits.hpp
@@ -25,7 +25,7 @@ template <typename Clock>
 struct wait_traits
 {
   /// Convert a clock duration into a duration used for waiting.
-  /** 
+  /**
    * @returns @c d.
    */
   static typename Clock::duration to_wait_duration(
@@ -33,6 +33,21 @@ struct wait_traits
   {
     return d;
   }
+
+  /// Convert a clock duration into a duration used for waiting.
+  /**
+   * @returns @c d.
+   */
+  static typename Clock::duration to_wait_duration(
+      const typename Clock::time_point& t)
+  {
+    typename Clock::time_point now = Clock::now();
+    if (now + (Clock::duration::max)() < t)
+      return (Clock::duration::max)();
+    if (now + (Clock::duration::min)() > t)
+      return (Clock::duration::min)();
+    return t - now;
+  }
 };
 
 } // namespace asio
diff --git a/include/boost/asio/waitable_timer_service.hpp b/include/boost/asio/waitable_timer_service.hpp
index 139d124ec5..882c6be66a 100644
--- a/include/boost/asio/waitable_timer_service.hpp
+++ b/include/boost/asio/waitable_timer_service.hpp
@@ -16,11 +16,14 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/chrono_time_traits.hpp>
 #include <boost/asio/detail/deadline_timer_service.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/wait_traits.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
@@ -33,7 +36,7 @@ template <typename Clock,
     typename WaitTraits = boost::asio::wait_traits<Clock> >
 class waitable_timer_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<
       waitable_timer_service<Clock, WaitTraits> >
@@ -42,7 +45,7 @@ class waitable_timer_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
   /// The clock type.
@@ -70,11 +73,11 @@ class waitable_timer_service
   typedef typename service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// Construct a new timer service for the specified io_service.
-  explicit waitable_timer_service(boost::asio::io_service& io_service)
+  /// Construct a new timer service for the specified io_context.
+  explicit waitable_timer_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        waitable_timer_service<Clock, WaitTraits> >(io_service),
-      service_impl_(io_service)
+        waitable_timer_service<Clock, WaitTraits> >(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -90,6 +93,23 @@ class waitable_timer_service
     service_impl_.destroy(impl);
   }
 
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a new timer implementation.
+  void move_construct(implementation_type& impl,
+      implementation_type& other_impl)
+  {
+    service_impl_.move_construct(impl, other_impl);
+  }
+
+  /// Move-assign from another timer implementation.
+  void move_assign(implementation_type& impl,
+      waitable_timer_service& other_service,
+      implementation_type& other_impl)
+  {
+    service_impl_.move_assign(impl, other_service.service_impl_, other_impl);
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
   /// Cancel any asynchronous wait operations associated with the timer.
   std::size_t cancel(implementation_type& impl, boost::system::error_code& ec)
   {
@@ -103,10 +123,19 @@ class waitable_timer_service
     return service_impl_.cancel_one(impl, ec);
   }
 
-  /// Get the expiry time for the timer as an absolute time.
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use expiry().) Get the expiry time for the timer as an
+  /// absolute time.
   time_point expires_at(const implementation_type& impl) const
   {
-    return service_impl_.expires_at(impl);
+    return service_impl_.expiry(impl);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the expiry time for the timer as an absolute time.
+  time_point expiry(const implementation_type& impl) const
+  {
+    return service_impl_.expiry(impl);
   }
 
   /// Set the expiry time for the timer as an absolute time.
@@ -116,18 +145,30 @@ class waitable_timer_service
     return service_impl_.expires_at(impl, expiry_time, ec);
   }
 
-  /// Get the expiry time for the timer relative to now.
+  /// Set the expiry time for the timer relative to now.
+  std::size_t expires_after(implementation_type& impl,
+      const duration& expiry_time, boost::system::error_code& ec)
+  {
+    return service_impl_.expires_after(impl, expiry_time, ec);
+  }
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use expiry().) Get the expiry time for the timer relative to
+  /// now.
   duration expires_from_now(const implementation_type& impl) const
   {
-    return service_impl_.expires_from_now(impl);
+    typedef detail::chrono_time_traits<Clock, WaitTraits> traits;
+    return traits::subtract(service_impl_.expiry(impl), traits::now());
   }
 
-  /// Set the expiry time for the timer relative to now.
+  /// (Deprecated: Use expires_after().) Set the expiry time for the timer
+  /// relative to now.
   std::size_t expires_from_now(implementation_type& impl,
       const duration& expiry_time, boost::system::error_code& ec)
   {
-    return service_impl_.expires_from_now(impl, expiry_time, ec);
+    return service_impl_.expires_after(impl, expiry_time, ec);
   }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   // Perform a blocking wait on the timer.
   void wait(implementation_type& impl, boost::system::error_code& ec)
@@ -142,20 +183,19 @@ class waitable_timer_service
   async_wait(implementation_type& impl,
       BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
   {
-    detail::async_result_init<
-      WaitHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
+    async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
 
-    service_impl_.async_wait(impl, init.handler);
+    service_impl_.async_wait(impl, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -167,4 +207,6 @@ class waitable_timer_service
 
 #include <boost/asio/detail/pop_options.hpp>
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WAITABLE_TIMER_SERVICE_HPP
diff --git a/include/boost/asio/windows/basic_handle.hpp b/include/boost/asio/windows/basic_handle.hpp
index 6f903fd454..d0eda784e5 100644
--- a/include/boost/asio/windows/basic_handle.hpp
+++ b/include/boost/asio/windows/basic_handle.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE) \
   || defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE) \
   || defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE) \
@@ -46,10 +48,6 @@ class basic_handle
   : public basic_io_object<HandleService>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// handle.
-  typedef typename HandleService::native_handle_type native_type;
-
   /// The native representation of a handle.
   typedef typename HandleService::native_handle_type native_handle_type;
 
@@ -60,11 +58,11 @@ class basic_handle
   /**
    * This constructor creates a handle without opening it.
    *
-   * @param io_service The io_service object that the handle will use to
+   * @param io_context The io_context object that the handle will use to
    * dispatch handlers for any asynchronous operations performed on the handle.
    */
-  explicit basic_handle(boost::asio::io_service& io_service)
-    : basic_io_object<HandleService>(io_service)
+  explicit basic_handle(boost::asio::io_context& io_context)
+    : basic_io_object<HandleService>(io_context)
   {
   }
 
@@ -72,16 +70,16 @@ class basic_handle
   /**
    * This constructor creates a handle object to hold an existing native handle.
    *
-   * @param io_service The io_service object that the handle will use to
+   * @param io_context The io_context object that the handle will use to
    * dispatch handlers for any asynchronous operations performed on the handle.
    *
    * @param handle A native handle.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_handle(boost::asio::io_service& io_service,
+  basic_handle(boost::asio::io_context& io_context,
       const native_handle_type& handle)
-    : basic_io_object<HandleService>(io_service)
+    : basic_io_object<HandleService>(io_context)
   {
     boost::system::error_code ec;
     this->get_service().assign(this->get_implementation(), handle, ec);
@@ -96,7 +94,7 @@ class basic_handle
    * @param other The other basic_handle object from which the move will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_handle(io_service&) constructor.
+   * constructed using the @c basic_handle(io_context&) constructor.
    */
   basic_handle(basic_handle&& other)
     : basic_io_object<HandleService>(
@@ -111,7 +109,7 @@ class basic_handle
    * @param other The other basic_handle object from which the move will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_handle(io_service&) constructor.
+   * constructed using the @c basic_handle(io_context&) constructor.
    */
   basic_handle& operator=(basic_handle&& other)
   {
@@ -172,10 +170,11 @@ class basic_handle
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code assign(const native_handle_type& handle,
+  BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& handle,
       boost::system::error_code& ec)
   {
-    return this->get_service().assign(this->get_implementation(), handle, ec);
+    this->get_service().assign(this->get_implementation(), handle, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the handle is open.
@@ -207,20 +206,10 @@ class basic_handle
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code close(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
-    return this->get_service().close(this->get_implementation(), ec);
-  }
-
-  /// (Deprecated: Use native_handle().) Get the native handle representation.
-  /**
-   * This function may be used to obtain the underlying representation of the
-   * handle. This is intended to allow access to native handle functionality
-   * that is not otherwise provided.
-   */
-  native_type native()
-  {
-    return this->get_service().native_handle(this->get_implementation());
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native handle representation.
@@ -257,9 +246,10 @@ class basic_handle
    *
    * @param ec Set to indicate what error occurred, if any.
    */
-  boost::system::error_code cancel(boost::system::error_code& ec)
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
-    return this->get_service().cancel(this->get_implementation(), ec);
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
 protected:
@@ -280,4 +270,6 @@ class basic_handle
        //   || defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WINDOWS_BASIC_HANDLE_HPP
diff --git a/include/boost/asio/windows/basic_object_handle.hpp b/include/boost/asio/windows/basic_object_handle.hpp
index c82c2a7039..0f2f278592 100644
--- a/include/boost/asio/windows/basic_object_handle.hpp
+++ b/include/boost/asio/windows/basic_object_handle.hpp
@@ -18,6 +18,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -53,11 +55,11 @@ class basic_object_handle
   /**
    * This constructor creates an object handle without opening it.
    *
-   * @param io_service The io_service object that the object handle will use to
+   * @param io_context The io_context object that the object handle will use to
    * dispatch handlers for any asynchronous operations performed on the handle.
    */
-  explicit basic_object_handle(boost::asio::io_service& io_service)
-    : basic_handle<ObjectHandleService>(io_service)
+  explicit basic_object_handle(boost::asio::io_context& io_context)
+    : basic_handle<ObjectHandleService>(io_context)
   {
   }
 
@@ -66,16 +68,16 @@ class basic_object_handle
    * This constructor creates an object handle object to hold an existing native
    * handle.
    *
-   * @param io_service The io_service object that the object handle will use to
+   * @param io_context The io_context object that the object handle will use to
    * dispatch handlers for any asynchronous operations performed on the handle.
    *
    * @param native_handle The new underlying handle implementation.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_object_handle(boost::asio::io_service& io_service,
+  basic_object_handle(boost::asio::io_context& io_context,
       const native_handle_type& native_handle)
-    : basic_handle<ObjectHandleService>(io_service, native_handle)
+    : basic_handle<ObjectHandleService>(io_context, native_handle)
   {
   }
 
@@ -88,7 +90,7 @@ class basic_object_handle
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_object_handle(io_service&) constructor.
+   * constructed using the @c basic_object_handle(io_context&) constructor.
    */
   basic_object_handle(basic_object_handle&& other)
     : basic_handle<ObjectHandleService>(
@@ -104,7 +106,7 @@ class basic_object_handle
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_object_handle(io_service&) constructor.
+   * constructed using the @c basic_object_handle(io_context&) constructor.
    */
   basic_object_handle& operator=(basic_object_handle&& other)
   {
@@ -156,7 +158,7 @@ class basic_object_handle
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    */
   template <typename WaitHandler>
   BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
@@ -177,4 +179,6 @@ class basic_object_handle
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WINDOWS_BASIC_OBJECT_HANDLE_HPP
diff --git a/include/boost/asio/windows/basic_random_access_handle.hpp b/include/boost/asio/windows/basic_random_access_handle.hpp
index 0d4184fb64..ae071896f8 100644
--- a/include/boost/asio/windows/basic_random_access_handle.hpp
+++ b/include/boost/asio/windows/basic_random_access_handle.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -47,10 +49,6 @@ class basic_random_access_handle
   : public basic_handle<RandomAccessHandleService>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// handle.
-  typedef typename RandomAccessHandleService::native_handle_type native_type;
-
   /// The native representation of a handle.
   typedef typename RandomAccessHandleService::native_handle_type
     native_handle_type;
@@ -60,12 +58,12 @@ class basic_random_access_handle
    * This constructor creates a random-access handle without opening it. The
    * handle needs to be opened before data can be written to or read from it.
    *
-   * @param io_service The io_service object that the random-access handle will
+   * @param io_context The io_context object that the random-access handle will
    * use to dispatch handlers for any asynchronous operations performed on the
    * handle.
    */
-  explicit basic_random_access_handle(boost::asio::io_service& io_service)
-    : basic_handle<RandomAccessHandleService>(io_service)
+  explicit basic_random_access_handle(boost::asio::io_context& io_context)
+    : basic_handle<RandomAccessHandleService>(io_context)
   {
   }
 
@@ -74,7 +72,7 @@ class basic_random_access_handle
    * This constructor creates a random-access handle object to hold an existing
    * native handle.
    *
-   * @param io_service The io_service object that the random-access handle will
+   * @param io_context The io_context object that the random-access handle will
    * use to dispatch handlers for any asynchronous operations performed on the
    * handle.
    *
@@ -82,9 +80,9 @@ class basic_random_access_handle
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_random_access_handle(boost::asio::io_service& io_service,
+  basic_random_access_handle(boost::asio::io_context& io_context,
       const native_handle_type& handle)
-    : basic_handle<RandomAccessHandleService>(io_service, handle)
+    : basic_handle<RandomAccessHandleService>(io_context, handle)
   {
   }
 
@@ -97,7 +95,7 @@ class basic_random_access_handle
    * move will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_random_access_handle(io_service&)
+   * constructed using the @c basic_random_access_handle(io_context&)
    * constructor.
    */
   basic_random_access_handle(basic_random_access_handle&& other)
@@ -115,7 +113,7 @@ class basic_random_access_handle
    * move will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_random_access_handle(io_service&)
+   * constructed using the @c basic_random_access_handle(io_context&)
    * constructor.
    */
   basic_random_access_handle& operator=(basic_random_access_handle&& other)
@@ -214,7 +212,7 @@ class basic_random_access_handle
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The write operation may not transmit all of the data to the peer.
    * Consider using the @ref async_write_at function if you need to ensure that
@@ -334,7 +332,7 @@ class basic_random_access_handle
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The read operation may not read all of the requested number of bytes.
    * Consider using the @ref async_read_at function if you need to ensure that
@@ -375,4 +373,6 @@ class basic_random_access_handle
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WINDOWS_BASIC_RANDOM_ACCESS_HANDLE_HPP
diff --git a/include/boost/asio/windows/basic_stream_handle.hpp b/include/boost/asio/windows/basic_stream_handle.hpp
index 1b954fffbd..2270847670 100644
--- a/include/boost/asio/windows/basic_stream_handle.hpp
+++ b/include/boost/asio/windows/basic_stream_handle.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -50,10 +52,6 @@ class basic_stream_handle
   : public basic_handle<StreamHandleService>
 {
 public:
-  /// (Deprecated: Use native_handle_type.) The native representation of a
-  /// handle.
-  typedef typename StreamHandleService::native_handle_type native_type;
-
   /// The native representation of a handle.
   typedef typename StreamHandleService::native_handle_type native_handle_type;
 
@@ -63,11 +61,11 @@ class basic_stream_handle
    * needs to be opened and then connected or accepted before data can be sent
    * or received on it.
    *
-   * @param io_service The io_service object that the stream handle will use to
+   * @param io_context The io_context object that the stream handle will use to
    * dispatch handlers for any asynchronous operations performed on the handle.
    */
-  explicit basic_stream_handle(boost::asio::io_service& io_service)
-    : basic_handle<StreamHandleService>(io_service)
+  explicit basic_stream_handle(boost::asio::io_context& io_context)
+    : basic_handle<StreamHandleService>(io_context)
   {
   }
 
@@ -76,16 +74,16 @@ class basic_stream_handle
    * This constructor creates a stream handle object to hold an existing native
    * handle.
    *
-   * @param io_service The io_service object that the stream handle will use to
+   * @param io_context The io_context object that the stream handle will use to
    * dispatch handlers for any asynchronous operations performed on the handle.
    *
    * @param handle The new underlying handle implementation.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
-  basic_stream_handle(boost::asio::io_service& io_service,
+  basic_stream_handle(boost::asio::io_context& io_context,
       const native_handle_type& handle)
-    : basic_handle<StreamHandleService>(io_service, handle)
+    : basic_handle<StreamHandleService>(io_context, handle)
   {
   }
 
@@ -98,7 +96,7 @@ class basic_stream_handle
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_handle(io_service&) constructor.
+   * constructed using the @c basic_stream_handle(io_context&) constructor.
    */
   basic_stream_handle(basic_stream_handle&& other)
     : basic_handle<StreamHandleService>(
@@ -115,7 +113,7 @@ class basic_stream_handle
    * will occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
-   * constructed using the @c basic_stream_handle(io_service&) constructor.
+   * constructed using the @c basic_stream_handle(io_context&) constructor.
    */
   basic_stream_handle& operator=(basic_stream_handle&& other)
   {
@@ -206,7 +204,7 @@ class basic_stream_handle
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The write operation may not transmit all of the data to the peer.
    * Consider using the @ref async_write function if you need to ensure that all
@@ -318,7 +316,7 @@ class basic_stream_handle
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the handler will not be invoked from within this function. Invocation
    * of the handler will be performed in a manner equivalent to using
-   * boost::asio::io_service::post().
+   * boost::asio::io_context::post().
    *
    * @note The read operation may not read all of the requested number of bytes.
    * Consider using the @ref async_read function if you need to ensure that the
@@ -358,4 +356,6 @@ class basic_stream_handle
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WINDOWS_BASIC_STREAM_HANDLE_HPP
diff --git a/include/boost/asio/windows/object_handle.hpp b/include/boost/asio/windows/object_handle.hpp
index 614cc6bf3e..33b252d495 100644
--- a/include/boost/asio/windows/object_handle.hpp
+++ b/include/boost/asio/windows/object_handle.hpp
@@ -21,19 +21,362 @@
 #if defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
-#include <boost/asio/windows/basic_object_handle.hpp>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/basic_io_object.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/detail/win_object_handle_service.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/windows/basic_object_handle.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#define BOOST_ASIO_SVC_T boost::asio::detail::win_object_handle_service
+
+#include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 namespace windows {
 
-/// Typedef for the typical usage of an object handle.
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+// Typedef for the typical usage of an object handle.
 typedef basic_object_handle<> object_handle;
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+/// Provides object-oriented handle functionality.
+/**
+ * The windows::object_handle class provides asynchronous and blocking
+ * object-oriented handle functionality.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+class object_handle
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>
+{
+public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
+  /// The native representation of a handle.
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef BOOST_ASIO_SVC_T::native_handle_type native_handle_type;
+#endif
+
+  /// An object_handle is always the lowest layer.
+  typedef object_handle lowest_layer_type;
+
+  /// Construct an object_handle without opening it.
+  /**
+   * This constructor creates an object handle without opening it.
+   *
+   * @param io_context The io_context object that the object handle will use to
+   * dispatch handlers for any asynchronous operations performed on the handle.
+   */
+  explicit object_handle(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+  }
+
+  /// Construct an object_handle on an existing native handle.
+  /**
+   * This constructor creates an object handle object to hold an existing native
+   * handle.
+   *
+   * @param io_context The io_context object that the object handle will use to
+   * dispatch handlers for any asynchronous operations performed on the handle.
+   *
+   * @param native_handle The new underlying handle implementation.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  object_handle(boost::asio::io_context& io_context,
+      const native_handle_type& native_handle)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(), native_handle, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct an object_handle from another.
+  /**
+   * This constructor moves an object handle from one object to another.
+   *
+   * @param other The other object_handle object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c object_handle(io_context&) constructor.
+   */
+  object_handle(object_handle&& other)
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
+  {
+  }
+
+  /// Move-assign an object_handle from another.
+  /**
+   * This assignment operator moves an object handle from one object to another.
+   *
+   * @param other The other object_handle object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c object_handle(io_context&) constructor.
+   */
+  object_handle& operator=(object_handle&& other)
+  {
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+
+  /// Get a reference to the lowest layer.
+  /**
+   * This function returns a reference to the lowest layer in a stack of
+   * layers. Since an object_handle cannot contain any further layers, it simply
+   * returns a reference to itself.
+   *
+   * @return A reference to the lowest layer in the stack of layers. Ownership
+   * is not transferred to the caller.
+   */
+  lowest_layer_type& lowest_layer()
+  {
+    return *this;
+  }
+
+  /// Get a const reference to the lowest layer.
+  /**
+   * This function returns a const reference to the lowest layer in a stack of
+   * layers. Since an object_handle cannot contain any further layers, it simply
+   * returns a reference to itself.
+   *
+   * @return A const reference to the lowest layer in the stack of layers.
+   * Ownership is not transferred to the caller.
+   */
+  const lowest_layer_type& lowest_layer() const
+  {
+    return *this;
+  }
+
+  /// Assign an existing native handle to the handle.
+  /*
+   * This function opens the handle to hold an existing native handle.
+   *
+   * @param handle A native handle.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void assign(const native_handle_type& handle)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(), handle, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+  /// Assign an existing native handle to the handle.
+  /*
+   * This function opens the handle to hold an existing native handle.
+   *
+   * @param handle A native handle.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& handle,
+      boost::system::error_code& ec)
+  {
+    this->get_service().assign(this->get_implementation(), handle, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Determine whether the handle is open.
+  bool is_open() const
+  {
+    return this->get_service().is_open(this->get_implementation());
+  }
+
+  /// Close the handle.
+  /**
+   * This function is used to close the handle. Any asynchronous read or write
+   * operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void close()
+  {
+    boost::system::error_code ec;
+    this->get_service().close(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "close");
+  }
+
+  /// Close the handle.
+  /**
+   * This function is used to close the handle. Any asynchronous read or write
+   * operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
+  {
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Get the native handle representation.
+  /**
+   * This function may be used to obtain the underlying representation of the
+   * handle. This is intended to allow access to native handle functionality
+   * that is not otherwise provided.
+   */
+  native_handle_type native_handle()
+  {
+    return this->get_service().native_handle(this->get_implementation());
+  }
+
+  /// Cancel all asynchronous operations associated with the handle.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void cancel()
+  {
+    boost::system::error_code ec;
+    this->get_service().cancel(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "cancel");
+  }
+
+  /// Cancel all asynchronous operations associated with the handle.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
+  {
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Perform a blocking wait on the object handle.
+  /**
+   * This function is used to wait for the object handle to be set to the
+   * signalled state. This function blocks and does not return until the object
+   * handle has been set to the signalled state.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void wait()
+  {
+    boost::system::error_code ec;
+    this->get_service().wait(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "wait");
+  }
+
+  /// Perform a blocking wait on the object handle.
+  /**
+   * This function is used to wait for the object handle to be set to the
+   * signalled state. This function blocks and does not return until the object
+   * handle has been set to the signalled state.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  void wait(boost::system::error_code& ec)
+  {
+    this->get_service().wait(this->get_implementation(), ec);
+  }
+
+  /// Start an asynchronous wait on the object handle.
+  /**
+   * This function is be used to initiate an asynchronous wait against the
+   * object handle. It always returns immediately.
+   *
+   * @param handler The handler to be called when the object handle is set to
+   * the signalled state. Copies will be made of the handler as required. The
+   * function signature of the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error // Result of operation.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   */
+  template <typename WaitHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WaitHandler,
+      void (boost::system::error_code))
+  async_wait(BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
+  {
+    boost::asio::async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
+
+    this->get_service().async_wait(this->get_implementation(),
+        init.completion_handler);
+
+    return init.result.get();
+  }
+};
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 } // namespace windows
 } // namespace asio
 } // namespace boost
 
+#include <boost/asio/detail/pop_options.hpp>
+
+#undef BOOST_ASIO_SVC_T
+
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
diff --git a/include/boost/asio/windows/object_handle_service.hpp b/include/boost/asio/windows/object_handle_service.hpp
index 26ef6ed507..6932d43c2b 100644
--- a/include/boost/asio/windows/object_handle_service.hpp
+++ b/include/boost/asio/windows/object_handle_service.hpp
@@ -18,13 +18,15 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/win_object_handle_service.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -35,7 +37,7 @@ namespace windows {
 /// Default service implementation for an object handle.
 class object_handle_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<object_handle_service>
 #endif
@@ -43,7 +45,7 @@ class object_handle_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
 private:
@@ -65,10 +67,10 @@ class object_handle_service
   typedef service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new object handle service for the specified io_service.
-  explicit object_handle_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<object_handle_service>(io_service),
-      service_impl_(io_service)
+  /// Construct a new object handle service for the specified io_context.
+  explicit object_handle_service(boost::asio::io_context& io_context)
+    : boost::asio::detail::service_base<object_handle_service>(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -102,10 +104,11 @@ class object_handle_service
   }
 
   /// Assign an existing native handle to an object handle.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const native_handle_type& handle, boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, handle, ec);
+    service_impl_.assign(impl, handle, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the handle is open.
@@ -115,10 +118,11 @@ class object_handle_service
   }
 
   /// Close an object handle implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native handle implementation.
@@ -128,10 +132,11 @@ class object_handle_service
   }
 
   /// Cancel all asynchronous operations associated with the handle.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   // Wait for a signaled state.
@@ -147,20 +152,19 @@ class object_handle_service
   async_wait(implementation_type& impl,
       BOOST_ASIO_MOVE_ARG(WaitHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      WaitHandler, void (boost::system::error_code)> init(
-        BOOST_ASIO_MOVE_CAST(WaitHandler)(handler));
+    boost::asio::async_completion<WaitHandler,
+      void (boost::system::error_code)> init(handler);
 
-    service_impl_.async_wait(impl, init.handler);
+    service_impl_.async_wait(impl, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -176,4 +180,6 @@ class object_handle_service
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_OBJECT_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WINDOWS_OBJECT_HANDLE_SERVICE_HPP
diff --git a/include/boost/asio/windows/overlapped_handle.hpp b/include/boost/asio/windows/overlapped_handle.hpp
new file mode 100644
index 0000000000..a21e11e965
--- /dev/null
+++ b/include/boost/asio/windows/overlapped_handle.hpp
@@ -0,0 +1,333 @@
+//
+// windows/overlapped_handle.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BOOST_ASIO_WINDOWS_OVERLAPPED_HANDLE_HPP
+#define BOOST_ASIO_WINDOWS_OVERLAPPED_HANDLE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+
+#if !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#if defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE) \
+  || defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE) \
+  || defined(GENERATING_DOCUMENTATION)
+
+#include <cstddef>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/basic_io_object.hpp>
+#include <boost/asio/detail/throw_error.hpp>
+#include <boost/asio/detail/win_iocp_handle_service.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+# include <utility>
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+#define BOOST_ASIO_SVC_T boost::asio::detail::win_iocp_handle_service
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace windows {
+
+/// Provides Windows handle functionality for objects that support
+/// overlapped I/O.
+/**
+ * The windows::overlapped_handle class provides the ability to wrap a Windows
+ * handle. The underlying object referred to by the handle must support
+ * overlapped I/O.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+class overlapped_handle
+  : BOOST_ASIO_SVC_ACCESS basic_io_object<BOOST_ASIO_SVC_T>
+{
+public:
+  /// The type of the executor associated with the object.
+  typedef io_context::executor_type executor_type;
+
+  /// The native representation of a handle.
+#if defined(GENERATING_DOCUMENTATION)
+  typedef implementation_defined native_handle_type;
+#else
+  typedef BOOST_ASIO_SVC_T::native_handle_type native_handle_type;
+#endif
+
+  /// An overlapped_handle is always the lowest layer.
+  typedef overlapped_handle lowest_layer_type;
+
+  /// Construct an overlapped_handle without opening it.
+  /**
+   * This constructor creates a handle without opening it.
+   *
+   * @param io_context The io_context object that the handle will use to
+   * dispatch handlers for any asynchronous operations performed on the handle.
+   */
+  explicit overlapped_handle(boost::asio::io_context& io_context)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+  }
+
+  /// Construct an overlapped_handle on an existing native handle.
+  /**
+   * This constructor creates a handle object to hold an existing native handle.
+   *
+   * @param io_context The io_context object that the handle will use to
+   * dispatch handlers for any asynchronous operations performed on the handle.
+   *
+   * @param handle A native handle.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  overlapped_handle(boost::asio::io_context& io_context,
+      const native_handle_type& handle)
+    : basic_io_object<BOOST_ASIO_SVC_T>(io_context)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(), handle, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct an overlapped_handle from another.
+  /**
+   * This constructor moves a handle from one object to another.
+   *
+   * @param other The other overlapped_handle object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c overlapped_handle(io_context&) constructor.
+   */
+  overlapped_handle(overlapped_handle&& other)
+    : basic_io_object<BOOST_ASIO_SVC_T>(std::move(other))
+  {
+  }
+
+  /// Move-assign an overlapped_handle from another.
+  /**
+   * This assignment operator moves a handle from one object to another.
+   *
+   * @param other The other overlapped_handle object from which the move will
+   * occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c overlapped_handle(io_context&) constructor.
+   */
+  overlapped_handle& operator=(overlapped_handle&& other)
+  {
+    basic_io_object<BOOST_ASIO_SVC_T>::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_context()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_context();
+  }
+
+  /// (Deprecated: Use get_executor().) Get the io_context associated with the
+  /// object.
+  /**
+   * This function may be used to obtain the io_context object that the I/O
+   * object uses to dispatch handlers for asynchronous operations.
+   *
+   * @return A reference to the io_context object that the I/O object will use
+   * to dispatch handlers. Ownership is not transferred to the caller.
+   */
+  boost::asio::io_context& get_io_service()
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_io_service();
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
+  {
+    return basic_io_object<BOOST_ASIO_SVC_T>::get_executor();
+  }
+
+  /// Get a reference to the lowest layer.
+  /**
+   * This function returns a reference to the lowest layer in a stack of
+   * layers. Since an overlapped_handle cannot contain any further layers, it
+   * simply returns a reference to itself.
+   *
+   * @return A reference to the lowest layer in the stack of layers. Ownership
+   * is not transferred to the caller.
+   */
+  lowest_layer_type& lowest_layer()
+  {
+    return *this;
+  }
+
+  /// Get a const reference to the lowest layer.
+  /**
+   * This function returns a const reference to the lowest layer in a stack of
+   * layers. Since an overlapped_handle cannot contain any further layers, it
+   * simply returns a reference to itself.
+   *
+   * @return A const reference to the lowest layer in the stack of layers.
+   * Ownership is not transferred to the caller.
+   */
+  const lowest_layer_type& lowest_layer() const
+  {
+    return *this;
+  }
+
+  /// Assign an existing native handle to the handle.
+  /*
+   * This function opens the handle to hold an existing native handle.
+   *
+   * @param handle A native handle.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void assign(const native_handle_type& handle)
+  {
+    boost::system::error_code ec;
+    this->get_service().assign(this->get_implementation(), handle, ec);
+    boost::asio::detail::throw_error(ec, "assign");
+  }
+
+  /// Assign an existing native handle to the handle.
+  /*
+   * This function opens the handle to hold an existing native handle.
+   *
+   * @param handle A native handle.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& handle,
+      boost::system::error_code& ec)
+  {
+    this->get_service().assign(this->get_implementation(), handle, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Determine whether the handle is open.
+  bool is_open() const
+  {
+    return this->get_service().is_open(this->get_implementation());
+  }
+
+  /// Close the handle.
+  /**
+   * This function is used to close the handle. Any asynchronous read or write
+   * operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void close()
+  {
+    boost::system::error_code ec;
+    this->get_service().close(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "close");
+  }
+
+  /// Close the handle.
+  /**
+   * This function is used to close the handle. Any asynchronous read or write
+   * operations will be cancelled immediately, and will complete with the
+   * boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
+  {
+    this->get_service().close(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Get the native handle representation.
+  /**
+   * This function may be used to obtain the underlying representation of the
+   * handle. This is intended to allow access to native handle functionality
+   * that is not otherwise provided.
+   */
+  native_handle_type native_handle()
+  {
+    return this->get_service().native_handle(this->get_implementation());
+  }
+
+  /// Cancel all asynchronous operations associated with the handle.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  void cancel()
+  {
+    boost::system::error_code ec;
+    this->get_service().cancel(this->get_implementation(), ec);
+    boost::asio::detail::throw_error(ec, "cancel");
+  }
+
+  /// Cancel all asynchronous operations associated with the handle.
+  /**
+   * This function causes all outstanding asynchronous read or write operations
+   * to finish immediately, and the handlers for cancelled operations will be
+   * passed the boost::asio::error::operation_aborted error.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   */
+  BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
+  {
+    this->get_service().cancel(this->get_implementation(), ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+protected:
+  /// Protected destructor to prevent deletion through this type.
+  /**
+   * This function destroys the handle, cancelling any outstanding asynchronous
+   * wait operations associated with the handle as if by calling @c cancel.
+   */
+  ~overlapped_handle()
+  {
+  }
+};
+
+} // namespace windows
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#undef BOOST_ASIO_SVC_T
+
+#endif // defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE)
+       //   || defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE)
+       //   || defined(GENERATING_DOCUMENTATION)
+
+#endif // !defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#endif // BOOST_ASIO_WINDOWS_OVERLAPPED_HANDLE_HPP
diff --git a/include/boost/asio/windows/overlapped_ptr.hpp b/include/boost/asio/windows/overlapped_ptr.hpp
index fa9fb3d200..5c6ce3a541 100644
--- a/include/boost/asio/windows/overlapped_ptr.hpp
+++ b/include/boost/asio/windows/overlapped_ptr.hpp
@@ -22,7 +22,7 @@
 
 #include <boost/asio/detail/noncopyable.hpp>
 #include <boost/asio/detail/win_iocp_overlapped_ptr.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -51,9 +51,9 @@ class overlapped_ptr
 
   /// Construct an overlapped_ptr to contain the specified handler.
   template <typename Handler>
-  explicit overlapped_ptr(boost::asio::io_service& io_service,
+  explicit overlapped_ptr(boost::asio::io_context& io_context,
       BOOST_ASIO_MOVE_ARG(Handler) handler)
-    : impl_(io_service, BOOST_ASIO_MOVE_CAST(Handler)(handler))
+    : impl_(io_context, BOOST_ASIO_MOVE_CAST(Handler)(handler))
   {
   }
 
@@ -71,10 +71,10 @@ class overlapped_ptr
   /// Reset to contain the specified handler, freeing any current OVERLAPPED
   /// object.
   template <typename Handler>
-  void reset(boost::asio::io_service& io_service,
+  void reset(boost::asio::io_context& io_context,
       BOOST_ASIO_MOVE_ARG(Handler) handler)
   {
-    impl_.reset(io_service, BOOST_ASIO_MOVE_CAST(Handler)(handler));
+    impl_.reset(io_context, BOOST_ASIO_MOVE_CAST(Handler)(handler));
   }
 
   /// Get the contained OVERLAPPED object.
diff --git a/include/boost/asio/windows/random_access_handle.hpp b/include/boost/asio/windows/random_access_handle.hpp
index 993e193278..76d2bd7010 100644
--- a/include/boost/asio/windows/random_access_handle.hpp
+++ b/include/boost/asio/windows/random_access_handle.hpp
@@ -16,23 +16,364 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <boost/asio/windows/overlapped_handle.hpp>
 
 #if defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
-#include <boost/asio/windows/basic_random_access_handle.hpp>
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/windows/basic_random_access_handle.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 namespace windows {
 
-/// Typedef for the typical usage of a random-access handle.
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+// Typedef for the typical usage of a random-access handle.
 typedef basic_random_access_handle<> random_access_handle;
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+/// Provides random-access handle functionality.
+/**
+ * The windows::random_access_handle class provides asynchronous and
+ * blocking random-access handle functionality.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ */
+class random_access_handle
+  : public overlapped_handle
+{
+public:
+  /// Construct a random_access_handle without opening it.
+  /**
+   * This constructor creates a random-access handle without opening it. The
+   * handle needs to be opened before data can be written to or read from it.
+   *
+   * @param io_context The io_context object that the random-access handle will
+   * use to dispatch handlers for any asynchronous operations performed on the
+   * handle.
+   */
+  explicit random_access_handle(boost::asio::io_context& io_context)
+    : overlapped_handle(io_context)
+  {
+  }
+
+  /// Construct a random_access_handle on an existing native handle.
+  /**
+   * This constructor creates a random-access handle object to hold an existing
+   * native handle.
+   *
+   * @param io_context The io_context object that the random-access handle will
+   * use to dispatch handlers for any asynchronous operations performed on the
+   * handle.
+   *
+   * @param handle The new underlying handle implementation.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  random_access_handle(boost::asio::io_context& io_context,
+      const native_handle_type& handle)
+    : overlapped_handle(io_context, handle)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a random_access_handle from another.
+  /**
+   * This constructor moves a random-access handle from one object to another.
+   *
+   * @param other The other random_access_handle object from which the
+   * move will occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c random_access_handle(io_context&)
+   * constructor.
+   */
+  random_access_handle(random_access_handle&& other)
+    : overlapped_handle(std::move(other))
+  {
+  }
+
+  /// Move-assign a random_access_handle from another.
+  /**
+   * This assignment operator moves a random-access handle from one object to
+   * another.
+   *
+   * @param other The other random_access_handle object from which the
+   * move will occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c random_access_handle(io_context&)
+   * constructor.
+   */
+  random_access_handle& operator=(random_access_handle&& other)
+  {
+    overlapped_handle::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Write some data to the handle at the specified offset.
+  /**
+   * This function is used to write data to the random-access handle. The
+   * function call will block until one or more bytes of the data has been
+   * written successfully, or until an error occurs.
+   *
+   * @param offset The offset at which the data will be written.
+   *
+   * @param buffers One or more data buffers to be written to the handle.
+   *
+   * @returns The number of bytes written.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The write_some_at operation may not write all of the data. Consider
+   * using the @ref write_at function if you need to ensure that all data is
+   * written before the blocking operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.write_some_at(42, boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some_at(uint64_t offset,
+      const ConstBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().write_some_at(
+        this->get_implementation(), offset, buffers, ec);
+    boost::asio::detail::throw_error(ec, "write_some_at");
+    return s;
+  }
+
+  /// Write some data to the handle at the specified offset.
+  /**
+   * This function is used to write data to the random-access handle. The
+   * function call will block until one or more bytes of the data has been
+   * written successfully, or until an error occurs.
+   *
+   * @param offset The offset at which the data will be written.
+   *
+   * @param buffers One or more data buffers to be written to the handle.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes written. Returns 0 if an error occurred.
+   *
+   * @note The write_some operation may not transmit all of the data to the
+   * peer. Consider using the @ref write_at function if you need to ensure that
+   * all data is written before the blocking operation completes.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some_at(uint64_t offset,
+      const ConstBufferSequence& buffers, boost::system::error_code& ec)
+  {
+    return this->get_service().write_some_at(
+        this->get_implementation(), offset, buffers, ec);
+  }
+
+  /// Start an asynchronous write at the specified offset.
+  /**
+   * This function is used to asynchronously write data to the random-access
+   * handle. The function call always returns immediately.
+   *
+   * @param offset The offset at which the data will be written.
+   *
+   * @param buffers One or more data buffers to be written to the handle.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the write operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes written.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The write operation may not transmit all of the data to the peer.
+   * Consider using the @ref async_write_at function if you need to ensure that
+   * all data is written before the asynchronous operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.async_write_some_at(42, boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence, typename WriteHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+      void (boost::system::error_code, std::size_t))
+  async_write_some_at(uint64_t offset,
+      const ConstBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WriteHandler.
+    BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
+
+    boost::asio::async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_write_some_at(this->get_implementation(),
+        offset, buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+
+  /// Read some data from the handle at the specified offset.
+  /**
+   * This function is used to read data from the random-access handle. The
+   * function call will block until one or more bytes of data has been read
+   * successfully, or until an error occurs.
+   *
+   * @param offset The offset at which the data will be read.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @returns The number of bytes read.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read_at function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.read_some_at(42, boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some_at(uint64_t offset,
+      const MutableBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().read_some_at(
+        this->get_implementation(), offset, buffers, ec);
+    boost::asio::detail::throw_error(ec, "read_some_at");
+    return s;
+  }
+
+  /// Read some data from the handle at the specified offset.
+  /**
+   * This function is used to read data from the random-access handle. The
+   * function call will block until one or more bytes of data has been read
+   * successfully, or until an error occurs.
+   *
+   * @param offset The offset at which the data will be read.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes read. Returns 0 if an error occurred.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read_at function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some_at(uint64_t offset,
+      const MutableBufferSequence& buffers, boost::system::error_code& ec)
+  {
+    return this->get_service().read_some_at(
+        this->get_implementation(), offset, buffers, ec);
+  }
+
+  /// Start an asynchronous read at the specified offset.
+  /**
+   * This function is used to asynchronously read data from the random-access
+   * handle. The function call always returns immediately.
+   *
+   * @param offset The offset at which the data will be read.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the read operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes read.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The read operation may not read all of the requested number of bytes.
+   * Consider using the @ref async_read_at function if you need to ensure that
+   * the requested amount of data is read before the asynchronous operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.async_read_some_at(42, boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence, typename ReadHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+      void (boost::system::error_code, std::size_t))
+  async_read_some_at(uint64_t offset,
+      const MutableBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a ReadHandler.
+    BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
+
+    boost::asio::async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_read_some_at(this->get_implementation(),
+        offset, buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+};
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 } // namespace windows
 } // namespace asio
 } // namespace boost
 
+#include <boost/asio/detail/pop_options.hpp>
+
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
diff --git a/include/boost/asio/windows/random_access_handle_service.hpp b/include/boost/asio/windows/random_access_handle_service.hpp
index 15a808f69a..a49a3955bd 100644
--- a/include/boost/asio/windows/random_access_handle_service.hpp
+++ b/include/boost/asio/windows/random_access_handle_service.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -25,7 +27,7 @@
 #include <boost/asio/detail/cstdint.hpp>
 #include <boost/asio/detail/win_iocp_handle_service.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -36,7 +38,7 @@ namespace windows {
 /// Default service implementation for a random-access handle.
 class random_access_handle_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<random_access_handle_service>
 #endif
@@ -44,7 +46,7 @@ class random_access_handle_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
 private:
@@ -59,13 +61,6 @@ class random_access_handle_service
   typedef service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native handle type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native handle type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -73,11 +68,11 @@ class random_access_handle_service
   typedef service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new random-access handle service for the specified io_service.
-  explicit random_access_handle_service(boost::asio::io_service& io_service)
+  /// Construct a new random-access handle service for the specified io_context.
+  explicit random_access_handle_service(boost::asio::io_context& io_context)
     : boost::asio::detail::service_base<
-        random_access_handle_service>(io_service),
-      service_impl_(io_service)
+        random_access_handle_service>(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -111,10 +106,11 @@ class random_access_handle_service
   }
 
   /// Assign an existing native handle to a random-access handle.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const native_handle_type& handle, boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, handle, ec);
+    service_impl_.assign(impl, handle, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the handle is open.
@@ -124,16 +120,11 @@ class random_access_handle_service
   }
 
   /// Close a random-access handle implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
-  }
-
-  /// (Deprecated: Use native_handle().) Get the native handle implementation.
-  native_type native(implementation_type& impl)
-  {
-    return service_impl_.native_handle(impl);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native handle implementation.
@@ -143,10 +134,11 @@ class random_access_handle_service
   }
 
   /// Cancel all asynchronous operations associated with the handle.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Write the given data at the specified offset.
@@ -165,11 +157,11 @@ class random_access_handle_service
       uint64_t offset, const ConstBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    boost::asio::async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_write_some_at(impl, offset, buffers, init.handler);
+    service_impl_.async_write_some_at(impl,
+        offset, buffers, init.completion_handler);
 
     return init.result.get();
   }
@@ -190,20 +182,20 @@ class random_access_handle_service
       uint64_t offset, const MutableBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    boost::asio::async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_read_some_at(impl, offset, buffers, init.handler);
+    service_impl_.async_read_some_at(impl,
+        offset, buffers, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -219,4 +211,6 @@ class random_access_handle_service
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WINDOWS_RANDOM_ACCESS_HANDLE_SERVICE_HPP
diff --git a/include/boost/asio/windows/stream_handle.hpp b/include/boost/asio/windows/stream_handle.hpp
index e52b8a16a6..1c7646a266 100644
--- a/include/boost/asio/windows/stream_handle.hpp
+++ b/include/boost/asio/windows/stream_handle.hpp
@@ -16,23 +16,348 @@
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
+#include <boost/asio/windows/overlapped_handle.hpp>
 
 #if defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
-#include <boost/asio/windows/basic_stream_handle.hpp>
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+# include <boost/asio/windows/basic_stream_handle.hpp>
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
+#include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 namespace windows {
 
-/// Typedef for the typical usage of a stream-oriented handle.
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+// Typedef for the typical usage of a stream-oriented handle.
 typedef basic_stream_handle<> stream_handle;
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+/// Provides stream-oriented handle functionality.
+/**
+ * The windows::stream_handle class provides asynchronous and blocking
+ * stream-oriented handle functionality.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ *
+ * @par Concepts:
+ * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream.
+ */
+class stream_handle
+  : public overlapped_handle
+{
+public:
+  /// Construct a stream_handle without opening it.
+  /**
+   * This constructor creates a stream handle without opening it. The handle
+   * needs to be opened and then connected or accepted before data can be sent
+   * or received on it.
+   *
+   * @param io_context The io_context object that the stream handle will use to
+   * dispatch handlers for any asynchronous operations performed on the handle.
+   */
+  explicit stream_handle(boost::asio::io_context& io_context)
+    : overlapped_handle(io_context)
+  {
+  }
+
+  /// Construct a stream_handle on an existing native handle.
+  /**
+   * This constructor creates a stream handle object to hold an existing native
+   * handle.
+   *
+   * @param io_context The io_context object that the stream handle will use to
+   * dispatch handlers for any asynchronous operations performed on the handle.
+   *
+   * @param handle The new underlying handle implementation.
+   *
+   * @throws boost::system::system_error Thrown on failure.
+   */
+  stream_handle(boost::asio::io_context& io_context,
+      const native_handle_type& handle)
+    : overlapped_handle(io_context, handle)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+  /// Move-construct a stream_handle from another.
+  /**
+   * This constructor moves a stream handle from one object to another.
+   *
+   * @param other The other stream_handle object from which the move
+   * will occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c stream_handle(io_context&) constructor.
+   */
+  stream_handle(stream_handle&& other)
+    : overlapped_handle(std::move(other))
+  {
+  }
+
+  /// Move-assign a stream_handle from another.
+  /**
+   * This assignment operator moves a stream handle from one object to
+   * another.
+   *
+   * @param other The other stream_handle object from which the move
+   * will occur.
+   *
+   * @note Following the move, the moved-from object is in the same state as if
+   * constructed using the @c stream_handle(io_context&) constructor.
+   */
+  stream_handle& operator=(stream_handle&& other)
+  {
+    overlapped_handle::operator=(std::move(other));
+    return *this;
+  }
+#endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
+
+  /// Write some data to the handle.
+  /**
+   * This function is used to write data to the stream handle. The function call
+   * will block until one or more bytes of the data has been written
+   * successfully, or until an error occurs.
+   *
+   * @param buffers One or more data buffers to be written to the handle.
+   *
+   * @returns The number of bytes written.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The write_some operation may not transmit all of the data to the
+   * peer. Consider using the @ref write function if you need to ensure that
+   * all data is written before the blocking operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.write_some(boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().write_some(
+        this->get_implementation(), buffers, ec);
+    boost::asio::detail::throw_error(ec, "write_some");
+    return s;
+  }
+
+  /// Write some data to the handle.
+  /**
+   * This function is used to write data to the stream handle. The function call
+   * will block until one or more bytes of the data has been written
+   * successfully, or until an error occurs.
+   *
+   * @param buffers One or more data buffers to be written to the handle.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes written. Returns 0 if an error occurred.
+   *
+   * @note The write_some operation may not transmit all of the data to the
+   * peer. Consider using the @ref write function if you need to ensure that
+   * all data is written before the blocking operation completes.
+   */
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers,
+      boost::system::error_code& ec)
+  {
+    return this->get_service().write_some(
+        this->get_implementation(), buffers, ec);
+  }
+
+  /// Start an asynchronous write.
+  /**
+   * This function is used to asynchronously write data to the stream handle.
+   * The function call always returns immediately.
+   *
+   * @param buffers One or more data buffers to be written to the handle.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the write operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes written.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The write operation may not transmit all of the data to the peer.
+   * Consider using the @ref async_write function if you need to ensure that all
+   * data is written before the asynchronous operation completes.
+   *
+   * @par Example
+   * To write a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.async_write_some(boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on writing multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename ConstBufferSequence, typename WriteHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+      void (boost::system::error_code, std::size_t))
+  async_write_some(const ConstBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a WriteHandler.
+    BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
+
+    boost::asio::async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_write_some(
+        this->get_implementation(), buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+
+  /// Read some data from the handle.
+  /**
+   * This function is used to read data from the stream handle. The function
+   * call will block until one or more bytes of data has been read successfully,
+   * or until an error occurs.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @returns The number of bytes read.
+   *
+   * @throws boost::system::system_error Thrown on failure. An error code of
+   * boost::asio::error::eof indicates that the connection was closed by the
+   * peer.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.read_some(boost::asio::buffer(data, size));
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers)
+  {
+    boost::system::error_code ec;
+    std::size_t s = this->get_service().read_some(
+        this->get_implementation(), buffers, ec);
+    boost::asio::detail::throw_error(ec, "read_some");
+    return s;
+  }
+
+  /// Read some data from the handle.
+  /**
+   * This function is used to read data from the stream handle. The function
+   * call will block until one or more bytes of data has been read successfully,
+   * or until an error occurs.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   *
+   * @param ec Set to indicate what error occurred, if any.
+   *
+   * @returns The number of bytes read. Returns 0 if an error occurred.
+   *
+   * @note The read_some operation may not read all of the requested number of
+   * bytes. Consider using the @ref read function if you need to ensure that
+   * the requested amount of data is read before the blocking operation
+   * completes.
+   */
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers,
+      boost::system::error_code& ec)
+  {
+    return this->get_service().read_some(
+        this->get_implementation(), buffers, ec);
+  }
+
+  /// Start an asynchronous read.
+  /**
+   * This function is used to asynchronously read data from the stream handle.
+   * The function call always returns immediately.
+   *
+   * @param buffers One or more buffers into which the data will be read.
+   * Although the buffers object may be copied as necessary, ownership of the
+   * underlying memory blocks is retained by the caller, which must guarantee
+   * that they remain valid until the handler is called.
+   *
+   * @param handler The handler to be called when the read operation completes.
+   * Copies will be made of the handler as required. The function signature of
+   * the handler must be:
+   * @code void handler(
+   *   const boost::system::error_code& error, // Result of operation.
+   *   std::size_t bytes_transferred           // Number of bytes read.
+   * ); @endcode
+   * Regardless of whether the asynchronous operation completes immediately or
+   * not, the handler will not be invoked from within this function. Invocation
+   * of the handler will be performed in a manner equivalent to using
+   * boost::asio::io_context::post().
+   *
+   * @note The read operation may not read all of the requested number of bytes.
+   * Consider using the @ref async_read function if you need to ensure that the
+   * requested amount of data is read before the asynchronous operation
+   * completes.
+   *
+   * @par Example
+   * To read into a single data buffer use the @ref buffer function as follows:
+   * @code
+   * handle.async_read_some(boost::asio::buffer(data, size), handler);
+   * @endcode
+   * See the @ref buffer documentation for information on reading into multiple
+   * buffers in one go, and how to use it with arrays, boost::array or
+   * std::vector.
+   */
+  template <typename MutableBufferSequence, typename ReadHandler>
+  BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
+      void (boost::system::error_code, std::size_t))
+  async_read_some(const MutableBufferSequence& buffers,
+      BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
+  {
+    // If you get an error on the following line it means that your handler does
+    // not meet the documented type requirements for a ReadHandler.
+    BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
+
+    boost::asio::async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
+
+    this->get_service().async_read_some(
+        this->get_implementation(), buffers, init.completion_handler);
+
+    return init.result.get();
+  }
+};
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
 
 } // namespace windows
 } // namespace asio
 } // namespace boost
 
+#include <boost/asio/detail/pop_options.hpp>
+
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
diff --git a/include/boost/asio/windows/stream_handle_service.hpp b/include/boost/asio/windows/stream_handle_service.hpp
index 5adcfaed1b..438954723c 100644
--- a/include/boost/asio/windows/stream_handle_service.hpp
+++ b/include/boost/asio/windows/stream_handle_service.hpp
@@ -17,6 +17,8 @@
 
 #include <boost/asio/detail/config.hpp>
 
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #if defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE) \
   || defined(GENERATING_DOCUMENTATION)
 
@@ -24,7 +26,7 @@
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/win_iocp_handle_service.hpp>
 #include <boost/asio/error.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
@@ -35,7 +37,7 @@ namespace windows {
 /// Default service implementation for a stream handle.
 class stream_handle_service
 #if defined(GENERATING_DOCUMENTATION)
-  : public boost::asio::io_service::service
+  : public boost::asio::io_context::service
 #else
   : public boost::asio::detail::service_base<stream_handle_service>
 #endif
@@ -43,7 +45,7 @@ class stream_handle_service
 public:
 #if defined(GENERATING_DOCUMENTATION)
   /// The unique service identifier.
-  static boost::asio::io_service::id id;
+  static boost::asio::io_context::id id;
 #endif
 
 private:
@@ -58,13 +60,6 @@ class stream_handle_service
   typedef service_impl_type::implementation_type implementation_type;
 #endif
 
-  /// (Deprecated: Use native_handle_type.) The native handle type.
-#if defined(GENERATING_DOCUMENTATION)
-  typedef implementation_defined native_type;
-#else
-  typedef service_impl_type::native_handle_type native_type;
-#endif
-
   /// The native handle type.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
@@ -72,10 +67,10 @@ class stream_handle_service
   typedef service_impl_type::native_handle_type native_handle_type;
 #endif
 
-  /// Construct a new stream handle service for the specified io_service.
-  explicit stream_handle_service(boost::asio::io_service& io_service)
-    : boost::asio::detail::service_base<stream_handle_service>(io_service),
-      service_impl_(io_service)
+  /// Construct a new stream handle service for the specified io_context.
+  explicit stream_handle_service(boost::asio::io_context& io_context)
+    : boost::asio::detail::service_base<stream_handle_service>(io_context),
+      service_impl_(io_context)
   {
   }
 
@@ -109,10 +104,11 @@ class stream_handle_service
   }
 
   /// Assign an existing native handle to a stream handle.
-  boost::system::error_code assign(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID assign(implementation_type& impl,
       const native_handle_type& handle, boost::system::error_code& ec)
   {
-    return service_impl_.assign(impl, handle, ec);
+    service_impl_.assign(impl, handle, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the handle is open.
@@ -122,16 +118,11 @@ class stream_handle_service
   }
 
   /// Close a stream handle implementation.
-  boost::system::error_code close(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID close(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.close(impl, ec);
-  }
-
-  /// (Deprecated: Use native_handle().) Get the native handle implementation.
-  native_type native(implementation_type& impl)
-  {
-    return service_impl_.native_handle(impl);
+    service_impl_.close(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Get the native handle implementation.
@@ -141,10 +132,11 @@ class stream_handle_service
   }
 
   /// Cancel all asynchronous operations associated with the handle.
-  boost::system::error_code cancel(implementation_type& impl,
+  BOOST_ASIO_SYNC_OP_VOID cancel(implementation_type& impl,
       boost::system::error_code& ec)
   {
-    return service_impl_.cancel(impl, ec);
+    service_impl_.cancel(impl, ec);
+    BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Write the given data to the stream.
@@ -163,11 +155,10 @@ class stream_handle_service
       const ConstBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      WriteHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(WriteHandler)(handler));
+    boost::asio::async_completion<WriteHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_write_some(impl, buffers, init.handler);
+    service_impl_.async_write_some(impl, buffers, init.completion_handler);
 
     return init.result.get();
   }
@@ -188,20 +179,19 @@ class stream_handle_service
       const MutableBufferSequence& buffers,
       BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
   {
-    boost::asio::detail::async_result_init<
-      ReadHandler, void (boost::system::error_code, std::size_t)> init(
-        BOOST_ASIO_MOVE_CAST(ReadHandler)(handler));
+    boost::asio::async_completion<ReadHandler,
+      void (boost::system::error_code, std::size_t)> init(handler);
 
-    service_impl_.async_read_some(impl, buffers, init.handler);
+    service_impl_.async_read_some(impl, buffers, init.completion_handler);
 
     return init.result.get();
   }
 
 private:
   // Destroy all user-defined handler objects owned by the service.
-  void shutdown_service()
+  void shutdown()
   {
-    service_impl_.shutdown_service();
+    service_impl_.shutdown();
   }
 
   // The platform-specific implementation.
@@ -217,4 +207,6 @@ class stream_handle_service
 #endif // defined(BOOST_ASIO_HAS_WINDOWS_STREAM_HANDLE)
        //   || defined(GENERATING_DOCUMENTATION)
 
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+
 #endif // BOOST_ASIO_WINDOWS_STREAM_HANDLE_SERVICE_HPP
diff --git a/include/boost/asio/write.hpp b/include/boost/asio/write.hpp
index b70e6f5bf5..87187c3d06 100644
--- a/include/boost/asio/write.hpp
+++ b/include/boost/asio/write.hpp
@@ -18,9 +18,13 @@
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
-#include <boost/asio/basic_streambuf_fwd.hpp>
+#include <boost/asio/buffer.hpp>
 #include <boost/asio/error.hpp>
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+# include <boost/asio/basic_streambuf_fwd.hpp>
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -70,7 +74,10 @@ namespace asio {
  *     boost::asio::transfer_all()); @endcode
  */
 template <typename SyncWriteStream, typename ConstBufferSequence>
-std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers);
+std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type* = 0);
 
 /// Write all of the supplied data to a stream before returning.
 /**
@@ -110,7 +117,10 @@ std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers);
  */
 template <typename SyncWriteStream, typename ConstBufferSequence>
 std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
-    boost::system::error_code& ec);
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type* = 0);
 
 /// Write a certain amount of data to a stream before returning.
 /**
@@ -161,7 +171,10 @@ std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
 template <typename SyncWriteStream, typename ConstBufferSequence,
     typename CompletionCondition>
 std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
-    CompletionCondition completion_condition);
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type* = 0);
 
 /// Write a certain amount of data to a stream before returning.
 /**
@@ -205,8 +218,172 @@ std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
 template <typename SyncWriteStream, typename ConstBufferSequence,
     typename CompletionCondition>
 std::size_t write(SyncWriteStream& s, const ConstBufferSequence& buffers,
-    CompletionCondition completion_condition, boost::system::error_code& ec);
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type* = 0);
+
+/// Write all of the supplied data to a stream before returning.
+/**
+ * This function is used to write a certain number of bytes of data to a stream.
+ * The call will block until one of the following conditions is true:
+ *
+ * @li All of the data in the supplied dynamic buffer sequence has been written.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * write_some function.
+ *
+ * @param s The stream to which the data is to be written. The type must support
+ * the SyncWriteStream concept.
+ *
+ * @param buffers The dynamic buffer sequence from which data will be written.
+ * Successfully written data is automatically consumed from the buffers.
+ *
+ * @returns The number of bytes transferred.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ *
+ * @note This overload is equivalent to calling:
+ * @code boost::asio::write(
+ *     s, buffers,
+ *     boost::asio::transfer_all()); @endcode
+ */
+template <typename SyncWriteStream, typename DynamicBuffer>
+std::size_t write(SyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+/// Write all of the supplied data to a stream before returning.
+/**
+ * This function is used to write a certain number of bytes of data to a stream.
+ * The call will block until one of the following conditions is true:
+ *
+ * @li All of the data in the supplied dynamic buffer sequence has been written.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * write_some function.
+ *
+ * @param s The stream to which the data is to be written. The type must support
+ * the SyncWriteStream concept.
+ *
+ * @param buffers The dynamic buffer sequence from which data will be written.
+ * Successfully written data is automatically consumed from the buffers.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes transferred.
+ *
+ * @note This overload is equivalent to calling:
+ * @code boost::asio::write(
+ *     s, buffers,
+ *     boost::asio::transfer_all(), ec); @endcode
+ */
+template <typename SyncWriteStream, typename DynamicBuffer>
+std::size_t write(SyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+/// Write a certain amount of data to a stream before returning.
+/**
+ * This function is used to write a certain number of bytes of data to a stream.
+ * The call will block until one of the following conditions is true:
+ *
+ * @li All of the data in the supplied dynamic buffer sequence has been written.
+ *
+ * @li The completion_condition function object returns 0.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * write_some function.
+ *
+ * @param s The stream to which the data is to be written. The type must support
+ * the SyncWriteStream concept.
+ *
+ * @param buffers The dynamic buffer sequence from which data will be written.
+ * Successfully written data is automatically consumed from the buffers.
+ *
+ * @param completion_condition The function object to be called to determine
+ * whether the write operation is complete. The signature of the function object
+ * must be:
+ * @code std::size_t completion_condition(
+ *   // Result of latest write_some operation.
+ *   const boost::system::error_code& error,
+ *
+ *   // Number of bytes transferred so far.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * A return value of 0 indicates that the write operation is complete. A
+ * non-zero return value indicates the maximum number of bytes to be written on
+ * the next call to the stream's write_some function.
+ *
+ * @returns The number of bytes transferred.
+ *
+ * @throws boost::system::system_error Thrown on failure.
+ */
+template <typename SyncWriteStream, typename DynamicBuffer,
+    typename CompletionCondition>
+std::size_t write(SyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+/// Write a certain amount of data to a stream before returning.
+/**
+ * This function is used to write a certain number of bytes of data to a stream.
+ * The call will block until one of the following conditions is true:
+ *
+ * @li All of the data in the supplied dynamic buffer sequence has been written.
+ *
+ * @li The completion_condition function object returns 0.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * write_some function.
+ *
+ * @param s The stream to which the data is to be written. The type must support
+ * the SyncWriteStream concept.
+ *
+ * @param buffers The dynamic buffer sequence from which data will be written.
+ * Successfully written data is automatically consumed from the buffers.
+ *
+ * @param completion_condition The function object to be called to determine
+ * whether the write operation is complete. The signature of the function object
+ * must be:
+ * @code std::size_t completion_condition(
+ *   // Result of latest write_some operation.
+ *   const boost::system::error_code& error,
+ *
+ *   // Number of bytes transferred so far.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * A return value of 0 indicates that the write operation is complete. A
+ * non-zero return value indicates the maximum number of bytes to be written on
+ * the next call to the stream's write_some function.
+ *
+ * @param ec Set to indicate what error occurred, if any.
+ *
+ * @returns The number of bytes written. If an error occurs, returns the total
+ * number of bytes successfully transferred prior to the error.
+ */
+template <typename SyncWriteStream, typename DynamicBuffer,
+    typename CompletionCondition>
+std::size_t write(SyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition, boost::system::error_code& ec,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Write all of the supplied data to a stream before returning.
@@ -350,6 +527,7 @@ std::size_t write(SyncWriteStream& s, basic_streambuf<Allocator>& b,
     CompletionCondition completion_condition, boost::system::error_code& ec);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 /**
@@ -401,7 +579,7 @@ std::size_t write(SyncWriteStream& s, basic_streambuf<Allocator>& b,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To write a single data buffer use the @ref buffer function as follows:
@@ -417,7 +595,10 @@ template <typename AsyncWriteStream, typename ConstBufferSequence,
 BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
     void (boost::system::error_code, std::size_t))
 async_write(AsyncWriteStream& s, const ConstBufferSequence& buffers,
-    BOOST_ASIO_MOVE_ARG(WriteHandler) handler);
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type* = 0);
 
 /// Start an asynchronous operation to write a certain amount of data to a
 /// stream.
@@ -474,7 +655,7 @@ async_write(AsyncWriteStream& s, const ConstBufferSequence& buffers,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To write a single data buffer use the @ref buffer function as follows:
@@ -492,8 +673,135 @@ BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
     void (boost::system::error_code, std::size_t))
 async_write(AsyncWriteStream& s, const ConstBufferSequence& buffers,
     CompletionCondition completion_condition,
-    BOOST_ASIO_MOVE_ARG(WriteHandler) handler);
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_const_buffer_sequence<ConstBufferSequence>::value
+    >::type* = 0);
+
+/// Start an asynchronous operation to write all of the supplied data to a
+/// stream.
+/**
+ * This function is used to asynchronously write a certain number of bytes of
+ * data to a stream. The function call always returns immediately. The
+ * asynchronous operation will continue until one of the following conditions
+ * is true:
+ *
+ * @li All of the data in the supplied dynamic buffer sequence has been written.
+ *
+ * @li An error occurred.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * async_write_some function, and is known as a <em>composed operation</em>. The
+ * program must ensure that the stream performs no other write operations (such
+ * as async_write, the stream's async_write_some function, or any other composed
+ * operations that perform writes) until this operation completes.
+ *
+ * @param s The stream to which the data is to be written. The type must support
+ * the AsyncWriteStream concept.
+ *
+ * @param buffers The dynamic buffer sequence from which data will be written.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called. Successfully written
+ * data is automatically consumed from the buffers.
+ *
+ * @param handler The handler to be called when the write operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   const boost::system::error_code& error, // Result of operation.
+ *
+ *   std::size_t bytes_transferred           // Number of bytes written from the
+ *                                           // buffers. If an error occurred,
+ *                                           // this will be less than the sum
+ *                                           // of the buffer sizes.
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
+ */
+template <typename AsyncWriteStream,
+    typename DynamicBuffer, typename WriteHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+    void (boost::system::error_code, std::size_t))
+async_write(AsyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
+
+/// Start an asynchronous operation to write a certain amount of data to a
+/// stream.
+/**
+ * This function is used to asynchronously write a certain number of bytes of
+ * data to a stream. The function call always returns immediately. The
+ * asynchronous operation will continue until one of the following conditions
+ * is true:
+ *
+ * @li All of the data in the supplied dynamic buffer sequence has been written.
+ *
+ * @li The completion_condition function object returns 0.
+ *
+ * This operation is implemented in terms of zero or more calls to the stream's
+ * async_write_some function, and is known as a <em>composed operation</em>. The
+ * program must ensure that the stream performs no other write operations (such
+ * as async_write, the stream's async_write_some function, or any other composed
+ * operations that perform writes) until this operation completes.
+ *
+ * @param s The stream to which the data is to be written. The type must support
+ * the AsyncWriteStream concept.
+ *
+ * @param buffers The dynamic buffer sequence from which data will be written.
+ * Although the buffers object may be copied as necessary, ownership of the
+ * underlying memory blocks is retained by the caller, which must guarantee
+ * that they remain valid until the handler is called. Successfully written
+ * data is automatically consumed from the buffers.
+ *
+ * @param completion_condition The function object to be called to determine
+ * whether the write operation is complete. The signature of the function object
+ * must be:
+ * @code std::size_t completion_condition(
+ *   // Result of latest async_write_some operation.
+ *   const boost::system::error_code& error,
+ *
+ *   // Number of bytes transferred so far.
+ *   std::size_t bytes_transferred
+ * ); @endcode
+ * A return value of 0 indicates that the write operation is complete. A
+ * non-zero return value indicates the maximum number of bytes to be written on
+ * the next call to the stream's async_write_some function.
+ *
+ * @param handler The handler to be called when the write operation completes.
+ * Copies will be made of the handler as required. The function signature of the
+ * handler must be:
+ * @code void handler(
+ *   const boost::system::error_code& error, // Result of operation.
+ *
+ *   std::size_t bytes_transferred           // Number of bytes written from the
+ *                                           // buffers. If an error occurred,
+ *                                           // this will be less than the sum
+ *                                           // of the buffer sizes.
+ * ); @endcode
+ * Regardless of whether the asynchronous operation completes immediately or
+ * not, the handler will not be invoked from within this function. Invocation of
+ * the handler will be performed in a manner equivalent to using
+ * boost::asio::io_context::post().
+ */
+template <typename AsyncWriteStream, typename DynamicBuffer,
+    typename CompletionCondition, typename WriteHandler>
+BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
+    void (boost::system::error_code, std::size_t))
+async_write(AsyncWriteStream& s,
+    BOOST_ASIO_MOVE_ARG(DynamicBuffer) buffers,
+    CompletionCondition completion_condition,
+    BOOST_ASIO_MOVE_ARG(WriteHandler) handler,
+    typename enable_if<
+      is_dynamic_buffer<DynamicBuffer>::value
+    >::type* = 0);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Start an asynchronous operation to write all of the supplied data to a
@@ -535,7 +843,7 @@ async_write(AsyncWriteStream& s, const ConstBufferSequence& buffers,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  */
 template <typename AsyncWriteStream, typename Allocator, typename WriteHandler>
 BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
@@ -596,7 +904,7 @@ async_write(AsyncWriteStream& s, basic_streambuf<Allocator>& b,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  */
 template <typename AsyncWriteStream, typename Allocator,
     typename CompletionCondition, typename WriteHandler>
@@ -607,6 +915,7 @@ async_write(AsyncWriteStream& s, basic_streambuf<Allocator>& b,
     BOOST_ASIO_MOVE_ARG(WriteHandler) handler);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 
diff --git a/include/boost/asio/write_at.hpp b/include/boost/asio/write_at.hpp
index 266fc5bcaf..91eb52ef34 100644
--- a/include/boost/asio/write_at.hpp
+++ b/include/boost/asio/write_at.hpp
@@ -18,10 +18,13 @@
 #include <boost/asio/detail/config.hpp>
 #include <cstddef>
 #include <boost/asio/async_result.hpp>
-#include <boost/asio/basic_streambuf_fwd.hpp>
 #include <boost/asio/detail/cstdint.hpp>
 #include <boost/asio/error.hpp>
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
+# include <boost/asio/basic_streambuf_fwd.hpp>
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
+
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
@@ -225,6 +228,7 @@ std::size_t write_at(SyncRandomAccessWriteDevice& d,
     uint64_t offset, const ConstBufferSequence& buffers,
     CompletionCondition completion_condition, boost::system::error_code& ec);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Write all of the supplied data at the specified offset before returning.
@@ -383,6 +387,7 @@ std::size_t write_at(SyncRandomAccessWriteDevice& d, uint64_t offset,
     boost::system::error_code& ec);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 /**
@@ -438,7 +443,7 @@ std::size_t write_at(SyncRandomAccessWriteDevice& d, uint64_t offset,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To write a single data buffer use the @ref buffer function as follows:
@@ -516,7 +521,7 @@ async_write_at(AsyncRandomAccessWriteDevice& d, uint64_t offset,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  *
  * @par Example
  * To write a single data buffer use the @ref buffer function as follows:
@@ -537,6 +542,7 @@ async_write_at(AsyncRandomAccessWriteDevice& d,
     CompletionCondition completion_condition,
     BOOST_ASIO_MOVE_ARG(WriteHandler) handler);
 
+#if !defined(BOOST_ASIO_NO_EXTENSIONS)
 #if !defined(BOOST_ASIO_NO_IOSTREAM)
 
 /// Start an asynchronous operation to write all of the supplied data at the
@@ -582,7 +588,7 @@ async_write_at(AsyncRandomAccessWriteDevice& d,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  */
 template <typename AsyncRandomAccessWriteDevice, typename Allocator,
     typename WriteHandler>
@@ -648,7 +654,7 @@ async_write_at(AsyncRandomAccessWriteDevice& d, uint64_t offset,
  * Regardless of whether the asynchronous operation completes immediately or
  * not, the handler will not be invoked from within this function. Invocation of
  * the handler will be performed in a manner equivalent to using
- * boost::asio::io_service::post().
+ * boost::asio::io_context::post().
  */
 template <typename AsyncRandomAccessWriteDevice, typename Allocator,
     typename CompletionCondition, typename WriteHandler>
@@ -659,6 +665,7 @@ async_write_at(AsyncRandomAccessWriteDevice& d, uint64_t offset,
     BOOST_ASIO_MOVE_ARG(WriteHandler) handler);
 
 #endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+#endif // !defined(BOOST_ASIO_NO_EXTENSIONS)
 
 /*@}*/
 
diff --git a/test/Jamfile b/test/Jamfile
index fb499a22f4..28e9edf11d 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -62,7 +62,7 @@ test-suite "asio"
   [ run generic/raw_protocol.cpp <template>asio_unit_test ]
   [ run generic/seq_packet_protocol.cpp <template>asio_unit_test ]
   [ run generic/stream_protocol.cpp <template>asio_unit_test ]
-  [ run io_service.cpp <template>asio_unit_test ]
+  [ run io_context.cpp <template>asio_unit_test ]
   [ run ip/address.cpp <template>asio_unit_test ]
   [ run ip/address_v4.cpp <template>asio_unit_test ]
   [ run ip/address_v6.cpp <template>asio_unit_test ]
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 8cd33b9ea9..5b0db56685 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -118,8 +118,8 @@ test-suite "asio" :
   [ link generic/stream_protocol.cpp : $(USE_SELECT) : generic_stream_protocol_select ]
   [ link high_resolution_timer.cpp ]
   [ link high_resolution_timer.cpp : $(USE_SELECT) : high_resolution_timer_select ]
-  [ run io_service.cpp ]
-  [ run io_service.cpp : : : $(USE_SELECT) : io_service_select ]
+  [ run io_context.cpp ]
+  [ run io_context.cpp : : : $(USE_SELECT) : io_context_select ]
   [ link ip/address.cpp : : ip_address ]
   [ link ip/address.cpp : $(USE_SELECT) : ip_address_select ]
   [ link ip/address_v4.cpp : : ip_address_v4 ]
diff --git a/test/archetypes/async_ops.hpp b/test/archetypes/async_ops.hpp
new file mode 100644
index 0000000000..4060081071
--- /dev/null
+++ b/test/archetypes/async_ops.hpp
@@ -0,0 +1,415 @@
+//
+// async_ops.hpp
+// ~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ARCHETYPES_ASYNC_OPS_HPP
+#define ARCHETYPES_ASYNC_OPS_HPP
+
+#include <boost/asio/associated_allocator.hpp>
+#include <boost/asio/associated_executor.hpp>
+#include <boost/asio/async_result.hpp>
+#include <boost/asio/error.hpp>
+
+#if defined(BOOST_ASIO_HAS_BOOST_BIND)
+# include <boost/bind.hpp>
+#else // defined(BOOST_ASIO_HAS_BOOST_BIND)
+# include <functional>
+#endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
+
+namespace archetypes {
+
+#if defined(BOOST_ASIO_HAS_BOOST_BIND)
+namespace bindns = boost;
+#else // defined(BOOST_ASIO_HAS_BOOST_BIND)
+namespace bindns = std;
+#endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void())
+async_op_0(BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void()>::completion_handler_type handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void()> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  ex.post(BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler), a);
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void(boost::system::error_code))
+async_op_ec_0(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code)>::completion_handler_type handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code()), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code(boost::asio::error::operation_aborted)), a);
+  }
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void(std::exception_ptr))
+async_op_ex_0(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr)>::completion_handler_type handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::exception_ptr()), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::make_exception_ptr(std::runtime_error("blah"))), a);
+  }
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void(int))
+async_op_1(BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(int)>::completion_handler_type handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(int)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  ex.post(
+      bindns::bind(
+        BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+        42), a);
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken,
+    void(boost::system::error_code, int))
+async_op_ec_1(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code, int)>::completion_handler_type
+      handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code, int)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code(), 42), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code(boost::asio::error::operation_aborted),
+          0), a);
+  }
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void(std::exception_ptr, int))
+async_op_ex_1(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr, int)>::completion_handler_type
+      handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr, int)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::exception_ptr(), 42), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::make_exception_ptr(std::runtime_error("blah")), 0), a);
+  }
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void(int, double))
+async_op_2(BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(int, double)>::completion_handler_type handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(int, double)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  ex.post(
+      bindns::bind(
+        BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+        42, 2.0), a);
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken,
+    void(boost::system::error_code, int, double))
+async_op_ec_2(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code, int, double)>::completion_handler_type
+      handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code, int, double)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code(), 42, 2.0), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code(boost::asio::error::operation_aborted),
+          0, 0.0), a);
+  }
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken,
+    void(std::exception_ptr, int, double))
+async_op_ex_2(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr, int, double)>::completion_handler_type
+      handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr, int, double)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::exception_ptr(), 42, 2.0), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::make_exception_ptr(std::runtime_error("blah")), 0, 0.0), a);
+  }
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken, void(int, double, char))
+async_op_3(BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(int, double, char)>::completion_handler_type handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(int, double, char)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  ex.post(
+      bindns::bind(
+        BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+        42, 2.0, 'a'), a);
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken,
+    void(boost::system::error_code, int, double, char))
+async_op_ec_3(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code, int, double, char)>::completion_handler_type
+      handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(boost::system::error_code, int, double, char)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code(), 42, 2.0, 'a'), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          boost::system::error_code(boost::asio::error::operation_aborted),
+          0, 0.0, 'z'), a);
+  }
+
+  return completion.result.get();
+}
+
+template <typename CompletionToken>
+BOOST_ASIO_INITFN_RESULT_TYPE(CompletionToken,
+    void(std::exception_ptr, int, double, char))
+async_op_ex_3(bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr, int, double, char)>::completion_handler_type
+      handler_type;
+
+  boost::asio::async_completion<CompletionToken,
+    void(std::exception_ptr, int, double, char)> completion(token);
+
+  typename boost::asio::associated_allocator<handler_type>::type a
+    = boost::asio::get_associated_allocator(completion.completion_handler);
+
+  typename boost::asio::associated_executor<handler_type>::type ex
+    = boost::asio::get_associated_executor(completion.completion_handler);
+
+  if (ok)
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::exception_ptr(), 42, 2.0, 'a'), a);
+  }
+  else
+  {
+    ex.post(
+        bindns::bind(
+          BOOST_ASIO_MOVE_CAST(handler_type)(completion.completion_handler),
+          std::make_exception_ptr(std::runtime_error("blah")),
+          0, 0.0, 'z'), a);
+  }
+
+  return completion.result.get();
+}
+
+} // namespace archetypes
+
+#endif // ARCHETYPES_ASYNC_OPS_HPP
diff --git a/test/archetypes/async_result.hpp b/test/archetypes/async_result.hpp
index b1e2218c85..8cb1771841 100644
--- a/test/archetypes/async_result.hpp
+++ b/test/archetypes/async_result.hpp
@@ -12,7 +12,6 @@
 #define ARCHETYPES_ASYNC_RESULT_HPP
 
 #include <boost/asio/async_result.hpp>
-#include <boost/asio/handler_type.hpp>
 
 namespace archetypes {
 
@@ -35,6 +34,12 @@ struct concrete_handler
   void operator()(Arg1, Arg2)
   {
   }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  concrete_handler(concrete_handler&&) {}
+private:
+  concrete_handler(const concrete_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 };
 
 } // namespace archetypes
@@ -43,28 +48,30 @@ namespace boost {
 namespace asio {
 
 template <typename Signature>
-struct handler_type<archetypes::lazy_handler, Signature>
-{
-  typedef archetypes::concrete_handler type;
-};
-
-template <>
-class async_result<archetypes::concrete_handler>
+class async_result<archetypes::lazy_handler, Signature>
 {
 public:
+  // The concrete completion handler type.
+  typedef archetypes::concrete_handler completion_handler_type;
+
   // The return type of the initiating function.
-  typedef int type;
+  typedef int return_type;
 
   // Construct an async_result from a given handler.
-  explicit async_result(archetypes::concrete_handler&)
+  explicit async_result(completion_handler_type&)
   {
   }
 
   // Obtain the value to be returned from the initiating function.
-  type get()
+  return_type get()
   {
     return 42;
   }
+
+private:
+  // Disallow copying and assignment.
+  async_result(const async_result&) BOOST_ASIO_DELETED;
+  async_result& operator=(const async_result&) BOOST_ASIO_DELETED;
 };
 
 } // namespace asio
diff --git a/test/archetypes/deprecated_async_ops.hpp b/test/archetypes/deprecated_async_ops.hpp
new file mode 100644
index 0000000000..332640849b
--- /dev/null
+++ b/test/archetypes/deprecated_async_ops.hpp
@@ -0,0 +1,345 @@
+//
+// deprecated_async_ops.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ARCHETYPES_DEPRECATED_ASYNC_OPS_HPP
+#define ARCHETYPES_DEPRECATED_ASYNC_OPS_HPP
+
+#include <boost/asio/async_result.hpp>
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+#include <boost/asio/handler_type.hpp>
+#include <boost/asio/error.hpp>
+#include <boost/asio/io_context.hpp>
+
+#if defined(BOOST_ASIO_HAS_BOOST_BIND)
+# include <boost/bind.hpp>
+#else // defined(BOOST_ASIO_HAS_BOOST_BIND)
+# include <functional>
+#endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
+
+namespace archetypes {
+
+#if defined(BOOST_ASIO_HAS_BOOST_BIND)
+namespace bindns = boost;
+#else // defined(BOOST_ASIO_HAS_BOOST_BIND)
+namespace bindns = std;
+#endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void()>::type>::type
+deprecated_async_op_0(boost::asio::io_context& ctx,
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void()>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler)));
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code)>::type>::type
+deprecated_async_op_ec_0(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code()));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code(boost::asio::error::operation_aborted)));
+  }
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr)>::type>::type
+deprecated_async_op_ex_0(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::exception_ptr()));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::make_exception_ptr(std::runtime_error("blah"))));
+  }
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(int)>::type>::type
+deprecated_async_op_1(boost::asio::io_context& ctx,
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(int)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler), 42));
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code, int)>::type>::type
+deprecated_async_op_ec_1(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code, int)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code(), 42));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code(boost::asio::error::operation_aborted), 0));
+  }
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr, int)>::type>::type
+deprecated_async_op_ex_1(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr, int)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::exception_ptr(), 42));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::make_exception_ptr(std::runtime_error("blah")), 0));
+  }
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(int, double)>::type>::type
+deprecated_async_op_2(boost::asio::io_context& ctx,
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(int, double)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+        42, 2.0));
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code, int, double)>::type>::type
+deprecated_async_op_ec_2(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code, int, double)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code(), 42, 2.0));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code(boost::asio::error::operation_aborted),
+          0, 0.0));
+  }
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr, int, double)>::type>::type
+deprecated_async_op_ex_2(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr, int, double)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::exception_ptr(), 42, 2.0));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::make_exception_ptr(std::runtime_error("blah")), 0, 0.0));
+  }
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(int, double, char)>::type>::type
+deprecated_async_op_3(boost::asio::io_context& ctx,
+    BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(int, double, char)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+        42, 2.0, 'a'));
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code, int, double, char)>::type>::type
+deprecated_async_op_ec_3(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(boost::system::error_code, int, double, char)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code(), 42, 2.0, 'a'));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          boost::system::error_code(boost::asio::error::operation_aborted),
+          0, 0.0, 'z'));
+  }
+
+  return result.get();
+}
+
+template <typename CompletionToken>
+typename boost::asio::async_result<
+  typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr, int, double, char)>::type>::type
+deprecated_async_op_ex_3(boost::asio::io_context& ctx,
+    bool ok, BOOST_ASIO_MOVE_ARG(CompletionToken) token)
+{
+  typedef typename boost::asio::handler_type<CompletionToken,
+    void(std::exception_ptr, int, double, char)>::type handler_type;
+
+  handler_type handler(BOOST_ASIO_MOVE_CAST(CompletionToken)(token));
+
+  boost::asio::async_result<handler_type> result(handler);
+
+  if (ok)
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::exception_ptr(), 42, 2.0, 'a'));
+  }
+  else
+  {
+    ctx.post(bindns::bind(BOOST_ASIO_MOVE_CAST(handler_type)(handler),
+          std::make_exception_ptr(std::runtime_error("blah")),
+          0, 0.0, 'z'));
+  }
+
+  return result.get();
+}
+
+} // namespace archetypes
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+#endif // ARCHETYPES_DEPRECATED_ASYNC_OPS_HPP
diff --git a/test/archetypes/deprecated_async_result.hpp b/test/archetypes/deprecated_async_result.hpp
new file mode 100644
index 0000000000..fbf56a673e
--- /dev/null
+++ b/test/archetypes/deprecated_async_result.hpp
@@ -0,0 +1,84 @@
+//
+// async_result.hpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ARCHETYPES_DEPRECATED_ASYNC_RESULT_HPP
+#define ARCHETYPES_DEPRECATED_ASYNC_RESULT_HPP
+
+#include <boost/asio/async_result.hpp>
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
+#include <boost/asio/handler_type.hpp>
+
+namespace archetypes {
+
+struct deprecated_lazy_handler
+{
+};
+
+struct deprecated_concrete_handler
+{
+  deprecated_concrete_handler(deprecated_lazy_handler)
+  {
+  }
+
+  template <typename Arg1>
+  void operator()(Arg1)
+  {
+  }
+
+  template <typename Arg1, typename Arg2>
+  void operator()(Arg1, Arg2)
+  {
+  }
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+  deprecated_concrete_handler(deprecated_concrete_handler&&) {}
+private:
+  deprecated_concrete_handler(const deprecated_concrete_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
+
+} // namespace archetypes
+
+namespace boost {
+namespace asio {
+
+template <typename Signature>
+struct handler_type<archetypes::deprecated_lazy_handler, Signature>
+{
+  typedef archetypes::deprecated_concrete_handler type;
+};
+
+template <>
+class async_result<archetypes::deprecated_concrete_handler>
+{
+public:
+  // The return type of the initiating function.
+  typedef double type;
+
+  // Construct an async_result from a given handler.
+  explicit async_result(archetypes::deprecated_concrete_handler&)
+  {
+  }
+
+  // Obtain the value to be returned from the initiating function.
+  type get()
+  {
+    return 42;
+  }
+};
+
+} // namespace asio
+} // namespace boost
+
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+#endif // ARCHETYPES_DEPRECATED_ASYNC_RESULT_HPP
diff --git a/test/associated_allocator.cpp b/test/associated_allocator.cpp
new file mode 100644
index 0000000000..a26ec693b9
--- /dev/null
+++ b/test/associated_allocator.cpp
@@ -0,0 +1,25 @@
+//
+// associated_allocator.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/associated_allocator.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "associated_allocator",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/associated_executor.cpp b/test/associated_executor.cpp
new file mode 100644
index 0000000000..5288943da8
--- /dev/null
+++ b/test/associated_executor.cpp
@@ -0,0 +1,25 @@
+//
+// associated_executor.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/associated_executor.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "associated_executor",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/ssl/stream_service.cpp b/test/async_result.cpp
similarity index 77%
rename from test/ssl/stream_service.cpp
rename to test/async_result.cpp
index 0180b274ac..d8011f9626 100644
--- a/test/ssl/stream_service.cpp
+++ b/test/async_result.cpp
@@ -1,6 +1,6 @@
 //
-// stream_service.cpp
-// ~~~~~~~~~~~~~~~~~~
+// async_result.cpp
+// ~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -14,12 +14,12 @@
 #endif // !defined(BOOST_ALL_NO_LIB)
 
 // Test that header file is self-contained.
-#include <boost/asio/ssl/stream_service.hpp>
+#include <boost/asio/async_result.hpp>
 
-#include "../unit_test.hpp"
+#include "unit_test.hpp"
 
 BOOST_ASIO_TEST_SUITE
 (
-  "ssl/stream_service",
+  "async_result",
   BOOST_ASIO_TEST_CASE(null_test)
 )
diff --git a/test/ssl/context_service.cpp b/test/bind_executor.cpp
similarity index 77%
rename from test/ssl/context_service.cpp
rename to test/bind_executor.cpp
index 0591a0e176..c70446b21b 100644
--- a/test/ssl/context_service.cpp
+++ b/test/bind_executor.cpp
@@ -1,6 +1,6 @@
 //
-// context_service.cpp
-// ~~~~~~~~~~~~~~~~~~~
+// bind_executor.cpp
+// ~~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -14,12 +14,12 @@
 #endif // !defined(BOOST_ALL_NO_LIB)
 
 // Test that header file is self-contained.
-#include <boost/asio/ssl/context_service.hpp>
+#include <boost/asio/bind_executor.hpp>
 
-#include "../unit_test.hpp"
+#include "unit_test.hpp"
 
 BOOST_ASIO_TEST_SUITE
 (
-  "ssl/context_service",
+  "bind_executor",
   BOOST_ASIO_TEST_CASE(null_test)
 )
diff --git a/test/buffer.cpp b/test/buffer.cpp
index 0a18e8bdc0..a8c593d5a7 100644
--- a/test/buffer.cpp
+++ b/test/buffer.cpp
@@ -57,9 +57,17 @@ void test()
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
     std::vector<char> vector_data(1024);
     const std::vector<char>& const_vector_data = vector_data;
-    const std::string string_data(1024, ' ');
+    std::string string_data(1024, ' ');
+    const std::string const_string_data(1024, ' ');
     std::vector<mutable_buffer> mutable_buffer_sequence;
     std::vector<const_buffer> const_buffer_sequence;
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_data(string_data);
+# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::string_view string_view_data(string_data);
+# endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
 
     // mutable_buffer constructors.
 
@@ -67,11 +75,22 @@ void test()
     mutable_buffer mb2(void_ptr_data, 1024);
     mutable_buffer mb3(mb1);
 
+    // mutable_buffer functions.
+
+    void* ptr1 = mb1.data();
+    (void)ptr1;
+
+    std::size_t n1 = mb1.size();
+    (void)n1;
+
     // mutable_buffer operators.
 
+    mb1 += 128;
     mb1 = mb2 + 128;
     mb1 = 128 + mb2;
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
     // mutable_buffers_1 constructors.
 
     mutable_buffers_1 mbc1(mb1);
@@ -84,6 +103,8 @@ void test()
     mutable_buffers_1::const_iterator iter2 = mbc1.end();
     (void)iter2;
 
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
     // const_buffer constructors.
 
     const_buffer cb1;
@@ -91,11 +112,22 @@ void test()
     const_buffer cb3(cb1);
     const_buffer cb4(mb1);
 
+    // const_buffer functions.
+
+    const void* ptr2 = cb1.data();
+    (void)ptr2;
+
+    std::size_t n2 = cb1.size();
+    (void)n2;
+
     // const_buffer operators.
 
+    cb1 += 128;
     cb1 = cb2 + 128;
     cb1 = 128 + cb2;
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+
     // const_buffers_1 constructors.
 
     const_buffers_1 cbc1(cb1);
@@ -108,16 +140,20 @@ void test()
     const_buffers_1::const_iterator iter4 = cbc1.end();
     (void)iter4;
 
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
     // buffer_size function overloads.
 
     std::size_t size1 = buffer_size(mb1);
     (void)size1;
     std::size_t size2 = buffer_size(cb1);
     (void)size2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size3 = buffer_size(mbc1);
     (void)size3;
     std::size_t size4 = buffer_size(cbc1);
     (void)size4;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size5 = buffer_size(mutable_buffer_sequence);
     (void)size5;
     std::size_t size6 = buffer_size(const_buffer_sequence);
@@ -125,10 +161,12 @@ void test()
 
     // buffer_cast function overloads.
 
-    void* ptr1 = buffer_cast<void*>(mb1);
-    (void)ptr1;
-    const void* ptr2 = buffer_cast<const void*>(cb1);
-    (void)ptr2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    void* ptr3 = buffer_cast<void*>(mb1);
+    (void)ptr3;
+    const void* ptr4 = buffer_cast<const void*>(cb1);
+    (void)ptr4;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // buffer function overloads.
 
@@ -162,21 +200,32 @@ void test()
     mb1 = buffer(vector_data, 1024);
     cb1 = buffer(const_vector_data);
     cb1 = buffer(const_vector_data, 1024);
-    cb1 = buffer(string_data);
-    cb1 = buffer(string_data, 1024);
+    mb1 = buffer(string_data);
+    mb1 = buffer(string_data, 1024);
+    cb1 = buffer(const_string_data);
+    cb1 = buffer(const_string_data, 1024);
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+    cb1 = buffer(string_view_data);
+    cb1 = buffer(string_view_data, 1024);
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
 
     // buffer_copy function overloads.
 
     std::size_t size7 = buffer_copy(mb1, cb2);
     (void)size7;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size8 = buffer_copy(mb1, cbc2);
     (void)size8;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size9 = buffer_copy(mb1, mb2);
     (void)size9;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size10 = buffer_copy(mb1, mbc2);
     (void)size10;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size11 = buffer_copy(mb1, const_buffer_sequence);
     (void)size11;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size12 = buffer_copy(mbc1, cb2);
     (void)size12;
     std::size_t size13 = buffer_copy(mbc1, cbc2);
@@ -187,27 +236,37 @@ void test()
     (void)size15;
     std::size_t size16 = buffer_copy(mbc1, const_buffer_sequence);
     (void)size16;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size17 = buffer_copy(mutable_buffer_sequence, cb2);
     (void)size17;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size18 = buffer_copy(mutable_buffer_sequence, cbc2);
     (void)size18;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size19 = buffer_copy(mutable_buffer_sequence, mb2);
     (void)size19;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size20 = buffer_copy(mutable_buffer_sequence, mbc2);
     (void)size20;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size21 = buffer_copy(
         mutable_buffer_sequence, const_buffer_sequence);
     (void)size21;
     std::size_t size22 = buffer_copy(mb1, cb2, 128);
     (void)size22;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size23 = buffer_copy(mb1, cbc2, 128);
     (void)size23;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size24 = buffer_copy(mb1, mb2, 128);
     (void)size24;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size25 = buffer_copy(mb1, mbc2, 128);
     (void)size25;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size26 = buffer_copy(mb1, const_buffer_sequence, 128);
     (void)size26;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size27 = buffer_copy(mbc1, cb2, 128);
     (void)size27;
     std::size_t size28 = buffer_copy(mbc1, cbc2, 128);
@@ -218,17 +277,71 @@ void test()
     (void)size30;
     std::size_t size31 = buffer_copy(mbc1, const_buffer_sequence, 128);
     (void)size31;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size32 = buffer_copy(mutable_buffer_sequence, cb2, 128);
     (void)size32;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size33 = buffer_copy(mutable_buffer_sequence, cbc2, 128);
     (void)size33;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size34 = buffer_copy(mutable_buffer_sequence, mb2, 128);
     (void)size34;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size35 = buffer_copy(mutable_buffer_sequence, mbc2, 128);
     (void)size35;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     std::size_t size36 = buffer_copy(
         mutable_buffer_sequence, const_buffer_sequence, 128);
     (void)size36;
+
+    // dynamic_buffer function overloads.
+
+    dynamic_string_buffer<char, std::string::traits_type,
+      std::string::allocator_type> db1 = dynamic_buffer(string_data);
+    (void)db1;
+    dynamic_string_buffer<char, std::string::traits_type,
+      std::string::allocator_type> db2 = dynamic_buffer(string_data, 1024);
+    (void)db2;
+    dynamic_vector_buffer<char, std::allocator<char> >
+      db3 = dynamic_buffer(vector_data);
+    (void)db3;
+    dynamic_vector_buffer<char, std::allocator<char> >
+      db4 = dynamic_buffer(vector_data, 1024);
+    (void)db4;
+
+    // dynamic_buffer member functions.
+
+    std::size_t size37 = db1.size();
+    (void)size37;
+    std::size_t size38 = db3.size();
+    (void)size38;
+
+    std::size_t size39 = db1.max_size();
+    (void)size39;
+    std::size_t size40 = db3.max_size();
+    (void)size40;
+
+    dynamic_string_buffer<char, std::string::traits_type,
+      std::string::allocator_type>::const_buffers_type
+        cb5 = db1.data();
+    (void)cb5;
+    dynamic_vector_buffer<char, std::allocator<char> >::const_buffers_type
+      cb6 = db3.data();
+    (void)cb6;
+
+    dynamic_string_buffer<char, std::string::traits_type,
+      std::string::allocator_type>::mutable_buffers_type mb5
+        = db1.prepare(1024);
+    (void)mb5;
+    dynamic_vector_buffer<char, std::allocator<char> >::mutable_buffers_type
+      mb6 = db3.prepare(1024);
+    (void)mb6;
+
+    db1.commit(1024);
+    db3.commit(1024);
+
+    db1.consume(1024);
+    db3.consume(1024);
   }
   catch (std::exception&)
   {
@@ -239,8 +352,216 @@ void test()
 
 //------------------------------------------------------------------------------
 
+namespace buffer_copy_runtime {
+
+using namespace boost::asio;
+using namespace std;
+
+void test()
+{
+  char dest_data[256];
+  char source_data[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mutable_buffer mb1 = boost::asio::buffer(dest_data);
+  mutable_buffer mb2 = boost::asio::buffer(source_data);
+  std::size_t n = buffer_copy(mb1, mb2);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  const_buffer cb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mb1, cb1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  mutable_buffers_1 mbc1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mb1, mbc1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  const_buffers_1 cbc1 = const_buffers_1(boost::asio::buffer(source_data));
+  n = buffer_copy(mb1, cbc1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  mb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mbc1, mb1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  cb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mbc1, cb1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  mutable_buffers_1 mbc2 = boost::asio::buffer(source_data);
+  n = buffer_copy(mbc1, mbc2);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  cbc1 = const_buffers_1(boost::asio::buffer(source_data));
+  n = buffer_copy(mbc1, cbc1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  std::vector<mutable_buffer> mv1;
+  mv1.push_back(boost::asio::buffer(source_data, 5));
+  mv1.push_back(boost::asio::buffer(source_data) + 5);
+  n = buffer_copy(mb1, mv1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  std::vector<const_buffer> cv1;
+  cv1.push_back(boost::asio::buffer(source_data, 6));
+  cv1.push_back(boost::asio::buffer(source_data) + 6);
+  n = buffer_copy(mb1, cv1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mv1.clear();
+  mv1.push_back(boost::asio::buffer(dest_data, 7));
+  mv1.push_back(boost::asio::buffer(dest_data) + 7);
+  cb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mv1, cb1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mv1.clear();
+  mv1.push_back(boost::asio::buffer(dest_data, 7));
+  mv1.push_back(boost::asio::buffer(dest_data) + 7);
+  cv1.clear();
+  cv1.push_back(boost::asio::buffer(source_data, 8));
+  cv1.push_back(boost::asio::buffer(source_data) + 8);
+  n = buffer_copy(mv1, cv1);
+  BOOST_ASIO_CHECK(n == sizeof(source_data));
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  mb2 = boost::asio::buffer(source_data);
+  n = buffer_copy(mb1, mb2, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  cb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mb1, cb1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  mbc1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mb1, mbc1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  cbc1 = const_buffers_1(boost::asio::buffer(source_data));
+  n = buffer_copy(mb1, cbc1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  mb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mbc1, mb1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  cb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mbc1, cb1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  mbc2 = boost::asio::buffer(source_data);
+  n = buffer_copy(mbc1, mbc2, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mbc1 = boost::asio::buffer(dest_data);
+  cbc1 = const_buffers_1(boost::asio::buffer(source_data));
+  n = buffer_copy(mbc1, cbc1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  mv1.clear();
+  mv1.push_back(boost::asio::buffer(source_data, 5));
+  mv1.push_back(boost::asio::buffer(source_data) + 5);
+  n = buffer_copy(mb1, mv1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mb1 = boost::asio::buffer(dest_data);
+  cv1.clear();
+  cv1.push_back(boost::asio::buffer(source_data, 6));
+  cv1.push_back(boost::asio::buffer(source_data) + 6);
+  n = buffer_copy(mb1, cv1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mv1.clear();
+  mv1.push_back(boost::asio::buffer(dest_data, 7));
+  mv1.push_back(boost::asio::buffer(dest_data) + 7);
+  cb1 = boost::asio::buffer(source_data);
+  n = buffer_copy(mv1, cb1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+
+  memset(dest_data, 0, sizeof(dest_data));
+  mv1.clear();
+  mv1.push_back(boost::asio::buffer(dest_data, 7));
+  mv1.push_back(boost::asio::buffer(dest_data) + 7);
+  cv1.clear();
+  cv1.push_back(boost::asio::buffer(source_data, 8));
+  cv1.push_back(boost::asio::buffer(source_data) + 8);
+  n = buffer_copy(mv1, cv1, 10);
+  BOOST_ASIO_CHECK(n == 10);
+  BOOST_ASIO_CHECK(memcmp(dest_data, source_data, n) == 0);
+}
+
+} // namespace buffer_copy_runtime
+
+//------------------------------------------------------------------------------
+
 BOOST_ASIO_TEST_SUITE
 (
   "buffer",
   BOOST_ASIO_COMPILE_TEST_CASE(buffer_compile::test)
+  BOOST_ASIO_TEST_CASE(buffer_copy_runtime::test)
 )
diff --git a/test/buffered_read_stream.cpp b/test/buffered_read_stream.cpp
index 0fa2175ea7..462c10cebf 100644
--- a/test/buffered_read_stream.cpp
+++ b/test/buffered_read_stream.cpp
@@ -19,7 +19,7 @@
 #include <cstring>
 #include "archetypes/async_result.hpp"
 #include <boost/asio/buffer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/system/system_error.hpp>
 #include "unit_test.hpp"
@@ -63,7 +63,7 @@ void test_compile()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     array<boost::asio::mutable_buffer, 2> mutable_buffers = {{
@@ -75,11 +75,19 @@ void test_compile()
     archetypes::lazy_handler lazy;
     boost::system::error_code ec;
 
-    stream_type stream1(ios);
-    stream_type stream2(ios, 1024);
+    stream_type stream1(ioc);
+    stream_type stream2(ioc, 1024);
 
-    io_service& ios_ref = stream1.get_io_service();
-    (void)ios_ref;
+    stream_type::executor_type ex = stream1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = stream1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = stream1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     stream_type::lowest_layer_type& lowest_layer = stream1.lowest_layer();
     (void)lowest_layer;
@@ -144,17 +152,17 @@ void test_sync_operations()
 {
   using namespace std; // For memcmp.
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
-  boost::asio::ip::tcp::acceptor acceptor(io_service,
+  boost::asio::ip::tcp::acceptor acceptor(io_context,
       boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 0));
   boost::asio::ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(boost::asio::ip::address_v4::loopback());
 
-  stream_type client_socket(io_service);
+  stream_type client_socket(io_context);
   client_socket.lowest_layer().connect(server_endpoint);
 
-  stream_type server_socket(io_service);
+  stream_type server_socket(io_context);
   acceptor.accept(server_socket.lowest_layer());
 
   const char write_data[]
@@ -255,20 +263,20 @@ void test_async_operations()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
-  boost::asio::ip::tcp::acceptor acceptor(io_service,
+  boost::asio::ip::tcp::acceptor acceptor(io_context,
       boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 0));
   boost::asio::ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(boost::asio::ip::address_v4::loopback());
 
-  stream_type client_socket(io_service);
+  stream_type client_socket(io_context);
   client_socket.lowest_layer().connect(server_endpoint);
 
-  stream_type server_socket(io_service);
+  stream_type server_socket(io_context);
   acceptor.async_accept(server_socket.lowest_layer(), &handle_accept);
-  io_service.run();
-  io_service.reset();
+  io_context.run();
+  io_context.restart();
 
   const char write_data[]
     = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
@@ -280,8 +288,8 @@ void test_async_operations()
     client_socket.async_write_some(
         boost::asio::buffer(write_buf + bytes_written),
         bindns::bind(handle_write, _1, _2, &bytes_written));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   char read_data[sizeof(write_data)];
@@ -293,8 +301,8 @@ void test_async_operations()
     server_socket.async_read_some(
         boost::asio::buffer(read_buf + bytes_read),
         bindns::bind(handle_read, _1, _2, &bytes_read));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   BOOST_ASIO_CHECK(bytes_written == sizeof(write_data));
@@ -307,8 +315,8 @@ void test_async_operations()
     server_socket.async_write_some(
         boost::asio::buffer(write_buf + bytes_written),
         bindns::bind(handle_write, _1, _2, &bytes_written));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   bytes_read = 0;
@@ -317,8 +325,8 @@ void test_async_operations()
     client_socket.async_read_some(
         boost::asio::buffer(read_buf + bytes_read),
         bindns::bind(handle_read, _1, _2, &bytes_read));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   BOOST_ASIO_CHECK(bytes_written == sizeof(write_data));
diff --git a/test/buffered_stream.cpp b/test/buffered_stream.cpp
index cd5d721759..f39401546c 100644
--- a/test/buffered_stream.cpp
+++ b/test/buffered_stream.cpp
@@ -19,7 +19,7 @@
 #include <cstring>
 #include "archetypes/async_result.hpp"
 #include <boost/asio/buffer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/system/system_error.hpp>
 #include "unit_test.hpp"
@@ -67,7 +67,7 @@ void test_compile()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     array<boost::asio::mutable_buffer, 2> mutable_buffers = {{
@@ -79,11 +79,19 @@ void test_compile()
     archetypes::lazy_handler lazy;
     boost::system::error_code ec;
 
-    stream_type stream1(ios);
-    stream_type stream2(ios, 1024, 1024);
+    stream_type stream1(ioc);
+    stream_type stream2(ioc, 1024, 1024);
 
-    io_service& ios_ref = stream1.get_io_service();
-    (void)ios_ref;
+    stream_type::executor_type ex = stream1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = stream1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = stream1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     stream_type::lowest_layer_type& lowest_layer = stream1.lowest_layer();
     (void)lowest_layer;
@@ -155,17 +163,17 @@ void test_sync_operations()
 {
   using namespace std; // For memcmp.
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
-  boost::asio::ip::tcp::acceptor acceptor(io_service,
+  boost::asio::ip::tcp::acceptor acceptor(io_context,
       boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 0));
   boost::asio::ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(boost::asio::ip::address_v4::loopback());
 
-  stream_type client_socket(io_service);
+  stream_type client_socket(io_context);
   client_socket.lowest_layer().connect(server_endpoint);
 
-  stream_type server_socket(io_service);
+  stream_type server_socket(io_context);
   acceptor.accept(server_socket.lowest_layer());
 
   const char write_data[]
@@ -273,20 +281,20 @@ void test_async_operations()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
-  boost::asio::ip::tcp::acceptor acceptor(io_service,
+  boost::asio::ip::tcp::acceptor acceptor(io_context,
       boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 0));
   boost::asio::ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(boost::asio::ip::address_v4::loopback());
 
-  stream_type client_socket(io_service);
+  stream_type client_socket(io_context);
   client_socket.lowest_layer().connect(server_endpoint);
 
-  stream_type server_socket(io_service);
+  stream_type server_socket(io_context);
   acceptor.async_accept(server_socket.lowest_layer(), &handle_accept);
-  io_service.run();
-  io_service.reset();
+  io_context.run();
+  io_context.restart();
 
   const char write_data[]
     = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
@@ -298,12 +306,12 @@ void test_async_operations()
     client_socket.async_write_some(
         boost::asio::buffer(write_buf + bytes_written),
         bindns::bind(handle_write, _1, _2, &bytes_written));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
     client_socket.async_flush(
         bindns::bind(handle_flush, _1));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   char read_data[sizeof(write_data)];
@@ -315,8 +323,8 @@ void test_async_operations()
     server_socket.async_read_some(
         boost::asio::buffer(read_buf + bytes_read),
         bindns::bind(handle_read, _1, _2, &bytes_read));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   BOOST_ASIO_CHECK(bytes_written == sizeof(write_data));
@@ -329,12 +337,12 @@ void test_async_operations()
     server_socket.async_write_some(
         boost::asio::buffer(write_buf + bytes_written),
         bindns::bind(handle_write, _1, _2, &bytes_written));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
     server_socket.async_flush(
         bindns::bind(handle_flush, _1));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   bytes_read = 0;
@@ -343,8 +351,8 @@ void test_async_operations()
     client_socket.async_read_some(
         boost::asio::buffer(read_buf + bytes_read),
         bindns::bind(handle_read, _1, _2, &bytes_read));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   BOOST_ASIO_CHECK(bytes_written == sizeof(write_data));
diff --git a/test/buffered_write_stream.cpp b/test/buffered_write_stream.cpp
index 02e4e6b265..f75a9f65c2 100644
--- a/test/buffered_write_stream.cpp
+++ b/test/buffered_write_stream.cpp
@@ -19,7 +19,7 @@
 #include <cstring>
 #include "archetypes/async_result.hpp"
 #include <boost/asio/buffer.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/system/system_error.hpp>
 #include "unit_test.hpp"
@@ -63,7 +63,7 @@ void test_compile()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     array<boost::asio::mutable_buffer, 2> mutable_buffers = {{
@@ -75,11 +75,19 @@ void test_compile()
     archetypes::lazy_handler lazy;
     boost::system::error_code ec;
 
-    stream_type stream1(ios);
-    stream_type stream2(ios, 1024);
+    stream_type stream1(ioc);
+    stream_type stream2(ioc, 1024);
 
-    io_service& ios_ref = stream1.get_io_service();
-    (void)ios_ref;
+    stream_type::executor_type ex = stream1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = stream1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = stream1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     stream_type::lowest_layer_type& lowest_layer = stream1.lowest_layer();
     (void)lowest_layer;
@@ -144,17 +152,17 @@ void test_sync_operations()
 {
   using namespace std; // For memcmp.
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
-  boost::asio::ip::tcp::acceptor acceptor(io_service,
+  boost::asio::ip::tcp::acceptor acceptor(io_context,
       boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 0));
   boost::asio::ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(boost::asio::ip::address_v4::loopback());
 
-  stream_type client_socket(io_service);
+  stream_type client_socket(io_context);
   client_socket.lowest_layer().connect(server_endpoint);
 
-  stream_type server_socket(io_service);
+  stream_type server_socket(io_context);
   acceptor.accept(server_socket.lowest_layer());
 
   const char write_data[]
@@ -262,20 +270,20 @@ void test_async_operations()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
-  boost::asio::ip::tcp::acceptor acceptor(io_service,
+  boost::asio::ip::tcp::acceptor acceptor(io_context,
       boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 0));
   boost::asio::ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(boost::asio::ip::address_v4::loopback());
 
-  stream_type client_socket(io_service);
+  stream_type client_socket(io_context);
   client_socket.lowest_layer().connect(server_endpoint);
 
-  stream_type server_socket(io_service);
+  stream_type server_socket(io_context);
   acceptor.async_accept(server_socket.lowest_layer(), &handle_accept);
-  io_service.run();
-  io_service.reset();
+  io_context.run();
+  io_context.restart();
 
   const char write_data[]
     = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
@@ -287,12 +295,12 @@ void test_async_operations()
     client_socket.async_write_some(
         boost::asio::buffer(write_buf + bytes_written),
         bindns::bind(handle_write, _1, _2, &bytes_written));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
     client_socket.async_flush(
         bindns::bind(handle_flush, _1));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   char read_data[sizeof(write_data)];
@@ -304,8 +312,8 @@ void test_async_operations()
     server_socket.async_read_some(
         boost::asio::buffer(read_buf + bytes_read),
         bindns::bind(handle_read, _1, _2, &bytes_read));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   BOOST_ASIO_CHECK(bytes_written == sizeof(write_data));
@@ -318,12 +326,12 @@ void test_async_operations()
     server_socket.async_write_some(
         boost::asio::buffer(write_buf + bytes_written),
         bindns::bind(handle_write, _1, _2, &bytes_written));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
     server_socket.async_flush(
         bindns::bind(handle_flush, _1));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   bytes_read = 0;
@@ -332,8 +340,8 @@ void test_async_operations()
     client_socket.async_read_some(
         boost::asio::buffer(read_buf + bytes_read),
         bindns::bind(handle_read, _1, _2, &bytes_read));
-    io_service.run();
-    io_service.reset();
+    io_context.run();
+    io_context.restart();
   }
 
   BOOST_ASIO_CHECK(bytes_written == sizeof(write_data));
diff --git a/test/buffers_iterator.cpp b/test/buffers_iterator.cpp
index 60a302242c..0ad82c5c9d 100644
--- a/test/buffers_iterator.cpp
+++ b/test/buffers_iterator.cpp
@@ -50,11 +50,11 @@ void test()
   {
     char data1[16], data2[16];
     const char cdata1[16] = "", cdata2[16] = "";
-    mutable_buffers_1 mb1 = buffer(data1);
+    mutable_buffer mb1 = buffer(data1);
     array<mutable_buffer, 2> mb2 = {{ buffer(data1), buffer(data2) }};
     std::vector<mutable_buffer> mb3;
     mb3.push_back(buffer(data1));
-    const_buffers_1 cb1 = buffer(cdata1);
+    const_buffer cb1 = buffer(cdata1);
     array<const_buffer, 2> cb2 = {{ buffer(cdata1), buffer(cdata2) }};
     vector<const_buffer> cb3;
     cb3.push_back(buffer(cdata1));
@@ -62,23 +62,23 @@ void test()
 
     // buffers_iterator constructors.
 
-    buffers_iterator<mutable_buffers_1, char> bi1;
-    buffers_iterator<mutable_buffers_1, const char> bi2;
+    buffers_iterator<mutable_buffer, char> bi1;
+    buffers_iterator<mutable_buffer, const char> bi2;
     buffers_iterator<array<mutable_buffer, 2>, char> bi3;
     buffers_iterator<array<mutable_buffer, 2>, const char> bi4;
     buffers_iterator<vector<mutable_buffer>, char> bi5;
     buffers_iterator<vector<mutable_buffer>, const char> bi6;
-    buffers_iterator<const_buffers_1, char> bi7;
-    buffers_iterator<const_buffers_1, const char> bi8;
+    buffers_iterator<const_buffer, char> bi7;
+    buffers_iterator<const_buffer, const char> bi8;
     buffers_iterator<array<const_buffer, 2>, char> bi9;
     buffers_iterator<array<const_buffer, 2>, const char> bi10;
     buffers_iterator<vector<const_buffer>, char> bi11;
     buffers_iterator<vector<const_buffer>, const char> bi12;
 
-    buffers_iterator<mutable_buffers_1, char> bi13(
-        buffers_iterator<mutable_buffers_1, char>::begin(mb1));
-    buffers_iterator<mutable_buffers_1, const char> bi14(
-        buffers_iterator<mutable_buffers_1, const char>::begin(mb1));
+    buffers_iterator<mutable_buffer, char> bi13(
+        buffers_iterator<mutable_buffer, char>::begin(mb1));
+    buffers_iterator<mutable_buffer, const char> bi14(
+        buffers_iterator<mutable_buffer, const char>::begin(mb1));
     buffers_iterator<array<mutable_buffer, 2>, char> bi15(
         buffers_iterator<array<mutable_buffer, 2>, char>::begin(mb2));
     buffers_iterator<array<mutable_buffer, 2>, const char> bi16(
@@ -87,10 +87,10 @@ void test()
         buffers_iterator<vector<mutable_buffer>, char>::begin(mb3));
     buffers_iterator<vector<mutable_buffer>, const char> bi18(
         buffers_iterator<vector<mutable_buffer>, const char>::begin(mb3));
-    buffers_iterator<const_buffers_1, char> bi19(
-        buffers_iterator<const_buffers_1, char>::begin(cb1));
-    buffers_iterator<const_buffers_1, const char> bi20(
-        buffers_iterator<const_buffers_1, const char>::begin(cb1));
+    buffers_iterator<const_buffer, char> bi19(
+        buffers_iterator<const_buffer, char>::begin(cb1));
+    buffers_iterator<const_buffer, const char> bi20(
+        buffers_iterator<const_buffer, const char>::begin(cb1));
     buffers_iterator<array<const_buffer, 2>, char> bi21(
         buffers_iterator<array<const_buffer, 2>, char>::begin(cb2));
     buffers_iterator<array<const_buffer, 2>, const char> bi22(
@@ -102,27 +102,27 @@ void test()
 
     // buffers_iterator member functions.
 
-    bi1 = buffers_iterator<mutable_buffers_1, char>::begin(mb1);
-    bi2 = buffers_iterator<mutable_buffers_1, const char>::begin(mb1);
+    bi1 = buffers_iterator<mutable_buffer, char>::begin(mb1);
+    bi2 = buffers_iterator<mutable_buffer, const char>::begin(mb1);
     bi3 = buffers_iterator<array<mutable_buffer, 2>, char>::begin(mb2);
     bi4 = buffers_iterator<array<mutable_buffer, 2>, const char>::begin(mb2);
     bi5 = buffers_iterator<vector<mutable_buffer>, char>::begin(mb3);
     bi6 = buffers_iterator<vector<mutable_buffer>, const char>::begin(mb3);
-    bi7 = buffers_iterator<const_buffers_1, char>::begin(cb1);
-    bi8 = buffers_iterator<const_buffers_1, const char>::begin(cb1);
+    bi7 = buffers_iterator<const_buffer, char>::begin(cb1);
+    bi8 = buffers_iterator<const_buffer, const char>::begin(cb1);
     bi9 = buffers_iterator<array<const_buffer, 2>, char>::begin(cb2);
     bi10 = buffers_iterator<array<const_buffer, 2>, const char>::begin(cb2);
     bi11 = buffers_iterator<vector<const_buffer>, char>::begin(cb3);
     bi12 = buffers_iterator<vector<const_buffer>, const char>::begin(cb3);
 
-    bi1 = buffers_iterator<mutable_buffers_1, char>::end(mb1);
-    bi2 = buffers_iterator<mutable_buffers_1, const char>::end(mb1);
+    bi1 = buffers_iterator<mutable_buffer, char>::end(mb1);
+    bi2 = buffers_iterator<mutable_buffer, const char>::end(mb1);
     bi3 = buffers_iterator<array<mutable_buffer, 2>, char>::end(mb2);
     bi4 = buffers_iterator<array<mutable_buffer, 2>, const char>::end(mb2);
     bi5 = buffers_iterator<vector<mutable_buffer>, char>::end(mb3);
     bi6 = buffers_iterator<vector<mutable_buffer>, const char>::end(mb3);
-    bi7 = buffers_iterator<const_buffers_1, char>::end(cb1);
-    bi8 = buffers_iterator<const_buffers_1, const char>::end(cb1);
+    bi7 = buffers_iterator<const_buffer, char>::end(cb1);
+    bi8 = buffers_iterator<const_buffer, const char>::end(cb1);
     bi9 = buffers_iterator<array<const_buffer, 2>, char>::end(cb2);
     bi10 = buffers_iterator<array<const_buffer, 2>, const char>::end(cb2);
     bi11 = buffers_iterator<vector<const_buffer>, char>::end(cb3);
diff --git a/test/deadline_timer.cpp b/test/deadline_timer.cpp
index ebc3ebc3f8..2fc769ed5e 100644
--- a/test/deadline_timer.cpp
+++ b/test/deadline_timer.cpp
@@ -22,7 +22,8 @@
 
 #include <boost/bind.hpp>
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/executor_work_guard.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/placeholders.hpp>
 #include <boost/asio/detail/thread.hpp>
 
@@ -79,12 +80,12 @@ ptime now()
 
 void deadline_timer_test()
 {
-  boost::asio::io_service ios;
+  boost::asio::io_context ioc;
   int count = 0;
 
   ptime start = now();
 
-  boost::asio::deadline_timer t1(ios, seconds(1));
+  boost::asio::deadline_timer t1(ioc, seconds(1));
   t1.wait();
 
   // The timer must block until after its expiry time.
@@ -94,7 +95,7 @@ void deadline_timer_test()
 
   start = now();
 
-  boost::asio::deadline_timer t2(ios, seconds(1) + microseconds(500000));
+  boost::asio::deadline_timer t2(ioc, seconds(1) + microseconds(500000));
   t2.wait();
 
   // The timer must block until after its expiry time.
@@ -122,13 +123,13 @@ void deadline_timer_test()
 
   start = now();
 
-  boost::asio::deadline_timer t3(ios, seconds(5));
+  boost::asio::deadline_timer t3(ioc, seconds(5));
   t3.async_wait(boost::bind(increment, &count));
 
   // No completions can be delivered until run() is called.
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all operations have finished, and
   // this should not be until after the timer's expiry time.
@@ -140,14 +141,14 @@ void deadline_timer_test()
   count = 3;
   start = now();
 
-  boost::asio::deadline_timer t4(ios, seconds(1));
+  boost::asio::deadline_timer t4(ioc, seconds(1));
   t4.async_wait(boost::bind(decrement_to_zero, &t4, &count));
 
   // No completions can be delivered until run() is called.
   BOOST_ASIO_CHECK(count == 3);
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // The run() call will not return until all operations have finished, and
   // this should not be until after the timer's final expiry time.
@@ -159,17 +160,17 @@ void deadline_timer_test()
   count = 0;
   start = now();
 
-  boost::asio::deadline_timer t5(ios, seconds(10));
+  boost::asio::deadline_timer t5(ioc, seconds(10));
   t5.async_wait(boost::bind(increment_if_not_cancelled, &count,
         boost::asio::placeholders::error));
-  boost::asio::deadline_timer t6(ios, seconds(1));
+  boost::asio::deadline_timer t6(ioc, seconds(1));
   t6.async_wait(boost::bind(cancel_timer, &t5));
 
   // No completions can be delivered until run() is called.
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // The timer should have been cancelled, so count should not have changed.
   // The total run time should not have been much more than 1 second (and
@@ -184,8 +185,8 @@ void deadline_timer_test()
   t5.async_wait(boost::bind(increment_if_not_cancelled, &count,
         boost::asio::placeholders::error));
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // The timer should not have been cancelled, so count should have changed.
   // The total time since the timer was created should be more than 10 seconds.
@@ -200,16 +201,16 @@ void deadline_timer_test()
   // Start two waits on a timer, one of which will be cancelled. The one
   // which is not cancelled should still run to completion and increment the
   // counter.
-  boost::asio::deadline_timer t7(ios, seconds(3));
+  boost::asio::deadline_timer t7(ioc, seconds(3));
   t7.async_wait(boost::bind(increment_if_not_cancelled, &count,
         boost::asio::placeholders::error));
   t7.async_wait(boost::bind(increment_if_not_cancelled, &count,
         boost::asio::placeholders::error));
-  boost::asio::deadline_timer t8(ios, seconds(1));
+  boost::asio::deadline_timer t8(ioc, seconds(1));
   t8.async_wait(boost::bind(cancel_one_timer, &t7));
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // One of the waits should not have been cancelled, so count should have
   // changed. The total time since the timer was created should be more than 3
@@ -226,11 +227,11 @@ void timer_handler(const boost::system::error_code&)
 
 void deadline_timer_cancel_test()
 {
-  static boost::asio::io_service io_service;
+  static boost::asio::io_context io_context;
   struct timer
   {
     boost::asio::deadline_timer t;
-    timer() : t(io_service) { t.expires_at(boost::posix_time::pos_infin); }
+    timer() : t(io_context) { t.expires_at(boost::posix_time::pos_infin); }
   } timers[50];
 
   timers[2].t.async_wait(&timer_handler);
@@ -267,11 +268,11 @@ void asio_handler_deallocate(void* pointer, std::size_t,
 
 void deadline_timer_custom_allocation_test()
 {
-  static boost::asio::io_service io_service;
+  static boost::asio::io_context io_context;
   struct timer
   {
     boost::asio::deadline_timer t;
-    timer() : t(io_service) {}
+    timer() : t(io_context) {}
   } timers[100];
 
   int allocation_count = 0;
@@ -291,25 +292,26 @@ void deadline_timer_custom_allocation_test()
   for (int i = 0; i < 50; ++i)
     timers[i].t.cancel();
 
-  io_service.run();
+  io_context.run();
 
   BOOST_ASIO_CHECK(allocation_count == 0);
 }
 
-void io_service_run(boost::asio::io_service* ios)
+void io_context_run(boost::asio::io_context* ioc)
 {
-  ios->run();
+  ioc->run();
 }
 
 void deadline_timer_thread_test()
 {
-  boost::asio::io_service ios;
-  boost::asio::io_service::work w(ios);
-  boost::asio::deadline_timer t1(ios);
-  boost::asio::deadline_timer t2(ios);
+  boost::asio::io_context ioc;
+  boost::asio::executor_work_guard<boost::asio::io_context::executor_type> work
+    = boost::asio::make_work_guard(ioc);
+  boost::asio::deadline_timer t1(ioc);
+  boost::asio::deadline_timer t2(ioc);
   int count = 0;
 
-  boost::asio::detail::thread th(boost::bind(io_service_run, &ios));
+  boost::asio::detail::thread th(boost::bind(io_context_run, &ioc));
 
   t2.expires_from_now(boost::posix_time::seconds(2));
   t2.wait();
@@ -320,7 +322,7 @@ void deadline_timer_thread_test()
   t2.expires_from_now(boost::posix_time::seconds(4));
   t2.wait();
 
-  ios.stop();
+  ioc.stop();
   th.join();
 
   BOOST_ASIO_CHECK(count == 1);
@@ -328,14 +330,47 @@ void deadline_timer_thread_test()
 
 void deadline_timer_async_result_test()
 {
-  boost::asio::io_service ios;
-  boost::asio::deadline_timer t1(ios);
+  boost::asio::io_context ioc;
+  boost::asio::deadline_timer t1(ioc);
 
   t1.expires_from_now(boost::posix_time::seconds(1));
   int i = t1.async_wait(archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
 
-  ios.run();
+  ioc.run();
+}
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+boost::asio::deadline_timer make_timer(boost::asio::io_context& ioc, int* count)
+{
+  boost::asio::deadline_timer t(ioc);
+  t.expires_from_now(boost::posix_time::seconds(1));
+  t.async_wait(boost::bind(increment, count));
+  return t;
+}
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+void deadline_timer_move_test()
+{
+#if defined(BOOST_ASIO_HAS_MOVE)
+  boost::asio::io_context io_context1;
+  boost::asio::io_context io_context2;
+  int count = 0;
+
+  boost::asio::deadline_timer t1 = make_timer(io_context1, &count);
+  boost::asio::deadline_timer t2 = make_timer(io_context2, &count);
+  boost::asio::deadline_timer t3 = std::move(t1);
+
+  t2 = std::move(t1);
+
+  io_context2.run();
+
+  BOOST_ASIO_CHECK(count == 1);
+
+  io_context1.run();
+
+  BOOST_ASIO_CHECK(count == 2);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 }
 
 BOOST_ASIO_TEST_SUITE
@@ -346,6 +381,7 @@ BOOST_ASIO_TEST_SUITE
   BOOST_ASIO_TEST_CASE(deadline_timer_custom_allocation_test)
   BOOST_ASIO_TEST_CASE(deadline_timer_thread_test)
   BOOST_ASIO_TEST_CASE(deadline_timer_async_result_test)
+  BOOST_ASIO_TEST_CASE(deadline_timer_move_test)
 )
 #else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 BOOST_ASIO_TEST_SUITE
diff --git a/test/defer.cpp b/test/defer.cpp
new file mode 100644
index 0000000000..107ff9fd16
--- /dev/null
+++ b/test/defer.cpp
@@ -0,0 +1,25 @@
+//
+// defer.cpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/defer.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "defer",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/dispatch.cpp b/test/dispatch.cpp
new file mode 100644
index 0000000000..45444e4ab9
--- /dev/null
+++ b/test/dispatch.cpp
@@ -0,0 +1,25 @@
+//
+// dispatch.cpp
+// ~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/dispatch.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "dispatch",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/execution_context.cpp b/test/execution_context.cpp
new file mode 100644
index 0000000000..71186c3be3
--- /dev/null
+++ b/test/execution_context.cpp
@@ -0,0 +1,25 @@
+//
+// execution_context.cpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/execution_context.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "execution_context",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/executor.cpp b/test/executor.cpp
new file mode 100644
index 0000000000..95e557ed9f
--- /dev/null
+++ b/test/executor.cpp
@@ -0,0 +1,25 @@
+//
+// executor.cpp
+// ~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/executor.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "executor",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/executor_work_guard.cpp b/test/executor_work_guard.cpp
new file mode 100644
index 0000000000..4f587f1b7f
--- /dev/null
+++ b/test/executor_work_guard.cpp
@@ -0,0 +1,25 @@
+//
+// executor_work_guard.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/executor_work_guard.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "executor_work_guard",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/generic/datagram_protocol.cpp b/test/generic/datagram_protocol.cpp
index f57380c0a3..38b4afdedd 100644
--- a/test/generic/datagram_protocol.cpp
+++ b/test/generic/datagram_protocol.cpp
@@ -17,7 +17,7 @@
 #include <boost/asio/generic/datagram_protocol.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include "../unit_test.hpp"
 
@@ -59,7 +59,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     socket_base::message_flags in_flags = 0;
@@ -69,33 +69,41 @@ void test()
 
     // basic_datagram_socket constructors.
 
-    dp::socket socket1(ios);
-    dp::socket socket2(ios, dp(af_inet, ipproto_udp));
-    dp::socket socket3(ios, dp::endpoint());
+    dp::socket socket1(ioc);
+    dp::socket socket2(ioc, dp(af_inet, ipproto_udp));
+    dp::socket socket3(ioc, dp::endpoint());
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
     dp::socket::native_handle_type native_socket1
       = ::socket(af_inet, sock_dgram, 0);
-    dp::socket socket4(ios, dp(af_inet, ipproto_udp), native_socket1);
+    dp::socket socket4(ioc, dp(af_inet, ipproto_udp), native_socket1);
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #if defined(BOOST_ASIO_HAS_MOVE)
     dp::socket socket5(std::move(socket4));
-    boost::asio::ip::udp::socket udp_socket(ios);
+    boost::asio::ip::udp::socket udp_socket(ioc);
     dp::socket socket6(std::move(udp_socket));
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_datagram_socket operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    socket1 = dp::socket(ios);
+    socket1 = dp::socket(ioc);
     socket1 = std::move(socket2);
-    socket1 = boost::asio::ip::udp::socket(ios);
+    socket1 = boost::asio::ip::udp::socket(ioc);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+    dp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = socket1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // basic_socket functions.
 
@@ -120,7 +128,7 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    dp::socket::native_type native_socket4 = socket1.native();
+    dp::socket::native_handle_type native_socket4 = socket1.native_handle();
     (void)native_socket4;
 
     socket1.cancel();
diff --git a/test/generic/raw_protocol.cpp b/test/generic/raw_protocol.cpp
index 3117a22b90..40da057d16 100644
--- a/test/generic/raw_protocol.cpp
+++ b/test/generic/raw_protocol.cpp
@@ -17,7 +17,7 @@
 #include <boost/asio/generic/raw_protocol.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/icmp.hpp>
 #include "../unit_test.hpp"
 
@@ -59,7 +59,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     socket_base::message_flags in_flags = 0;
@@ -69,33 +69,41 @@ void test()
 
     // basic_raw_socket constructors.
 
-    rp::socket socket1(ios);
-    rp::socket socket2(ios, rp(af_inet, ipproto_icmp));
-    rp::socket socket3(ios, rp::endpoint());
+    rp::socket socket1(ioc);
+    rp::socket socket2(ioc, rp(af_inet, ipproto_icmp));
+    rp::socket socket3(ioc, rp::endpoint());
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
     rp::socket::native_handle_type native_socket1
       = ::socket(af_inet, sock_raw, 0);
-    rp::socket socket4(ios, rp(af_inet, ipproto_icmp), native_socket1);
+    rp::socket socket4(ioc, rp(af_inet, ipproto_icmp), native_socket1);
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #if defined(BOOST_ASIO_HAS_MOVE)
     rp::socket socket5(std::move(socket4));
-    boost::asio::ip::icmp::socket icmp_socket(ios);
+    boost::asio::ip::icmp::socket icmp_socket(ioc);
     rp::socket socket6(std::move(icmp_socket));
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_datagram_socket operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    socket1 = rp::socket(ios);
+    socket1 = rp::socket(ioc);
     socket1 = std::move(socket2);
-    socket1 = boost::asio::ip::icmp::socket(ios);
+    socket1 = boost::asio::ip::icmp::socket(ioc);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+    rp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = socket1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // basic_socket functions.
 
@@ -120,7 +128,7 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    rp::socket::native_type native_socket4 = socket1.native();
+    rp::socket::native_handle_type native_socket4 = socket1.native_handle();
     (void)native_socket4;
 
     socket1.cancel();
diff --git a/test/generic/seq_packet_protocol.cpp b/test/generic/seq_packet_protocol.cpp
index 89809bf2a7..1033e0ea7c 100644
--- a/test/generic/seq_packet_protocol.cpp
+++ b/test/generic/seq_packet_protocol.cpp
@@ -17,7 +17,7 @@
 #include <boost/asio/generic/seq_packet_protocol.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../unit_test.hpp"
 
 #if defined(__cplusplus_cli) || defined(__cplusplus_winrt)
@@ -57,7 +57,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     const socket_base::message_flags in_flags = 0;
@@ -68,13 +68,13 @@ void test()
 
     // basic_seq_packet_socket constructors.
 
-    spp::socket socket1(ios);
-    spp::socket socket2(ios, spp(af_inet, 0));
-    spp::socket socket3(ios, spp::endpoint());
+    spp::socket socket1(ioc);
+    spp::socket socket2(ioc, spp(af_inet, 0));
+    spp::socket socket3(ioc, spp::endpoint());
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
     spp::socket::native_handle_type native_socket1
       = ::socket(af_inet, sock_seqpacket, 0);
-    spp::socket socket4(ios, spp(af_inet, 0), native_socket1);
+    spp::socket socket4(ioc, spp(af_inet, 0), native_socket1);
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #if defined(BOOST_ASIO_HAS_MOVE)
@@ -84,14 +84,22 @@ void test()
     // basic_seq_packet_socket operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    socket1 = spp::socket(ios);
+    socket1 = spp::socket(ioc);
     socket1 = std::move(socket2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+    spp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = socket1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // basic_socket functions.
 
@@ -116,7 +124,7 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    spp::socket::native_type native_socket4 = socket1.native();
+    spp::socket::native_handle_type native_socket4 = socket1.native_handle();
     (void)native_socket4;
 
     socket1.cancel();
diff --git a/test/generic/stream_protocol.cpp b/test/generic/stream_protocol.cpp
index 0f28b7b5b4..3ab99260f8 100644
--- a/test/generic/stream_protocol.cpp
+++ b/test/generic/stream_protocol.cpp
@@ -17,7 +17,7 @@
 #include <boost/asio/generic/stream_protocol.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include "../unit_test.hpp"
 
@@ -67,7 +67,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     socket_base::message_flags in_flags = 0;
@@ -77,35 +77,43 @@ void test()
 
     // basic_stream_socket constructors.
 
-    sp::socket socket1(ios);
-    sp::socket socket2(ios, sp(af_inet, ipproto_tcp));
-    sp::socket socket3(ios, sp::endpoint());
+    sp::socket socket1(ioc);
+    sp::socket socket2(ioc, sp(af_inet, ipproto_tcp));
+    sp::socket socket3(ioc, sp::endpoint());
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
     Windows::Networking::Sockets::StreamSocket^ native_socket1 = nullptr;
 #else // defined(BOOST_ASIO_WINDOWS_RUNTIME)
     sp::socket::native_handle_type native_socket1
       = ::socket(af_inet, sock_stream, 0);
 #endif // defined(BOOST_ASIO_WINDOWS_RUNTIME)
-    sp::socket socket4(ios, sp(af_inet, ipproto_tcp), native_socket1);
+    sp::socket socket4(ioc, sp(af_inet, ipproto_tcp), native_socket1);
 
 #if defined(BOOST_ASIO_HAS_MOVE)
     sp::socket socket5(std::move(socket4));
-    boost::asio::ip::tcp::socket tcp_socket(ios);
+    boost::asio::ip::tcp::socket tcp_socket(ioc);
     sp::socket socket6(std::move(tcp_socket));
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_stream_socket operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    socket1 = sp::socket(ios);
+    socket1 = sp::socket(ioc);
     socket1 = std::move(socket2);
-    socket1 = boost::asio::ip::tcp::socket(ios);
+    socket1 = boost::asio::ip::tcp::socket(ioc);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+    sp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = socket1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // basic_socket functions.
 
@@ -136,7 +144,7 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    sp::socket::native_type native_socket4 = socket1.native();
+    sp::socket::native_handle_type native_socket4 = socket1.native_handle();
     (void)native_socket4;
 
     socket1.cancel();
diff --git a/test/io_service.cpp b/test/io_context.cpp
similarity index 50%
rename from test/io_service.cpp
rename to test/io_context.cpp
index 80e76d115d..5ed369bc45 100644
--- a/test/io_service.cpp
+++ b/test/io_context.cpp
@@ -1,5 +1,5 @@
 //
-// io_service.cpp
+// io_context.cpp
 // ~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
@@ -14,9 +14,12 @@
 #endif // !defined(BOOST_ALL_NO_LIB)
 
 // Test that header file is self-contained.
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 
 #include <sstream>
+#include <boost/asio/bind_executor.hpp>
+#include <boost/asio/dispatch.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/detail/thread.hpp>
 #include "unit_test.hpp"
 
@@ -43,12 +46,9 @@ namespace bindns = std;
 #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 typedef deadline_timer timer;
 namespace chronons = boost::posix_time;
-#elif defined(BOOST_ASIO_HAS_STD_CHRONO)
+#elif defined(BOOST_ASIO_HAS_CHRONO)
 typedef steady_timer timer;
-namespace chronons = std::chrono;
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-typedef steady_timer timer;
-namespace chronons = boost::chrono;
+namespace chronons = boost::asio::chrono;
 #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 
 void increment(int* count)
@@ -56,50 +56,51 @@ void increment(int* count)
   ++(*count);
 }
 
-void decrement_to_zero(io_service* ios, int* count)
+void decrement_to_zero(io_context* ioc, int* count)
 {
   if (*count > 0)
   {
     --(*count);
 
     int before_value = *count;
-    ios->post(bindns::bind(decrement_to_zero, ios, count));
+    boost::asio::post(*ioc, bindns::bind(decrement_to_zero, ioc, count));
 
     // Handler execution cannot nest, so count value should remain unchanged.
     BOOST_ASIO_CHECK(*count == before_value);
   }
 }
 
-void nested_decrement_to_zero(io_service* ios, int* count)
+void nested_decrement_to_zero(io_context* ioc, int* count)
 {
   if (*count > 0)
   {
     --(*count);
 
-    ios->dispatch(bindns::bind(nested_decrement_to_zero, ios, count));
+    boost::asio::dispatch(*ioc,
+        bindns::bind(nested_decrement_to_zero, ioc, count));
 
     // Handler execution is nested, so count value should now be zero.
     BOOST_ASIO_CHECK(*count == 0);
   }
 }
 
-void sleep_increment(io_service* ios, int* count)
+void sleep_increment(io_context* ioc, int* count)
 {
-  timer t(*ios, chronons::seconds(2));
+  timer t(*ioc, chronons::seconds(2));
   t.wait();
 
   if (++(*count) < 3)
-    ios->post(bindns::bind(sleep_increment, ios, count));
+    boost::asio::post(*ioc, bindns::bind(sleep_increment, ioc, count));
 }
 
-void start_sleep_increments(io_service* ios, int* count)
+void start_sleep_increments(io_context* ioc, int* count)
 {
   // Give all threads a chance to start.
-  timer t(*ios, chronons::seconds(2));
+  timer t(*ioc, chronons::seconds(2));
   t.wait();
 
   // Start the first of three increments.
-  ios->post(bindns::bind(sleep_increment, ios, count));
+  boost::asio::post(*ioc, bindns::bind(sleep_increment, ioc, count));
 }
 
 void throw_exception()
@@ -107,158 +108,160 @@ void throw_exception()
   throw 1;
 }
 
-void io_service_run(io_service* ios)
+void io_context_run(io_context* ioc)
 {
-  ios->run();
+  ioc->run();
 }
 
-void io_service_test()
+void io_context_test()
 {
-  io_service ios;
+  io_context ioc;
   int count = 0;
 
-  ios.post(bindns::bind(increment, &count));
+  boost::asio::post(ioc, bindns::bind(increment, &count));
 
   // No handlers can be called until run() is called.
-  BOOST_ASIO_CHECK(!ios.stopped());
+  BOOST_ASIO_CHECK(!ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 1);
 
   count = 0;
-  ios.reset();
-  ios.post(bindns::bind(increment, &count));
-  ios.post(bindns::bind(increment, &count));
-  ios.post(bindns::bind(increment, &count));
-  ios.post(bindns::bind(increment, &count));
-  ios.post(bindns::bind(increment, &count));
+  ioc.restart();
+  boost::asio::post(ioc, bindns::bind(increment, &count));
+  boost::asio::post(ioc, bindns::bind(increment, &count));
+  boost::asio::post(ioc, bindns::bind(increment, &count));
+  boost::asio::post(ioc, bindns::bind(increment, &count));
+  boost::asio::post(ioc, bindns::bind(increment, &count));
 
   // No handlers can be called until run() is called.
-  BOOST_ASIO_CHECK(!ios.stopped());
+  BOOST_ASIO_CHECK(!ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 5);
 
   count = 0;
-  ios.reset();
-  io_service::work* w = new io_service::work(ios);
-  ios.post(bindns::bind(&io_service::stop, &ios));
-  BOOST_ASIO_CHECK(!ios.stopped());
-  ios.run();
+  ioc.restart();
+  executor_work_guard<io_context::executor_type> w = make_work_guard(ioc);
+  boost::asio::post(ioc, bindns::bind(&io_context::stop, &ioc));
+  BOOST_ASIO_CHECK(!ioc.stopped());
+  ioc.run();
 
   // The only operation executed should have been to stop run().
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.reset();
-  ios.post(bindns::bind(increment, &count));
-  delete w;
+  ioc.restart();
+  boost::asio::post(ioc, bindns::bind(increment, &count));
+  w.reset();
 
   // No handlers can be called until run() is called.
-  BOOST_ASIO_CHECK(!ios.stopped());
+  BOOST_ASIO_CHECK(!ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 1);
 
   count = 10;
-  ios.reset();
-  ios.post(bindns::bind(decrement_to_zero, &ios, &count));
+  ioc.restart();
+  boost::asio::post(ioc, bindns::bind(decrement_to_zero, &ioc, &count));
 
   // No handlers can be called until run() is called.
-  BOOST_ASIO_CHECK(!ios.stopped());
+  BOOST_ASIO_CHECK(!ioc.stopped());
   BOOST_ASIO_CHECK(count == 10);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
 
   count = 10;
-  ios.reset();
-  ios.post(bindns::bind(nested_decrement_to_zero, &ios, &count));
+  ioc.restart();
+  boost::asio::post(ioc, bindns::bind(nested_decrement_to_zero, &ioc, &count));
 
   // No handlers can be called until run() is called.
-  BOOST_ASIO_CHECK(!ios.stopped());
+  BOOST_ASIO_CHECK(!ioc.stopped());
   BOOST_ASIO_CHECK(count == 10);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
 
   count = 10;
-  ios.reset();
-  ios.dispatch(bindns::bind(nested_decrement_to_zero, &ios, &count));
+  ioc.restart();
+  boost::asio::dispatch(ioc,
+      bindns::bind(nested_decrement_to_zero, &ioc, &count));
 
   // No handlers can be called until run() is called, even though nested
   // delivery was specifically allowed in the previous call.
-  BOOST_ASIO_CHECK(!ios.stopped());
+  BOOST_ASIO_CHECK(!ioc.stopped());
   BOOST_ASIO_CHECK(count == 10);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
 
   count = 0;
   int count2 = 0;
-  ios.reset();
-  BOOST_ASIO_CHECK(!ios.stopped());
-  ios.post(bindns::bind(start_sleep_increments, &ios, &count));
-  ios.post(bindns::bind(start_sleep_increments, &ios, &count2));
-  boost::asio::detail::thread thread1(bindns::bind(io_service_run, &ios));
-  boost::asio::detail::thread thread2(bindns::bind(io_service_run, &ios));
+  ioc.restart();
+  BOOST_ASIO_CHECK(!ioc.stopped());
+  boost::asio::post(ioc, bindns::bind(start_sleep_increments, &ioc, &count));
+  boost::asio::post(ioc, bindns::bind(start_sleep_increments, &ioc, &count2));
+  boost::asio::detail::thread thread1(bindns::bind(io_context_run, &ioc));
+  boost::asio::detail::thread thread2(bindns::bind(io_context_run, &ioc));
   thread1.join();
   thread2.join();
 
   // The run() calls will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 3);
   BOOST_ASIO_CHECK(count2 == 3);
 
   count = 10;
-  io_service ios2;
-  ios.dispatch(ios2.wrap(bindns::bind(decrement_to_zero, &ios2, &count)));
-  ios.reset();
-  BOOST_ASIO_CHECK(!ios.stopped());
-  ios.run();
+  io_context ioc2;
+  boost::asio::dispatch(ioc, boost::asio::bind_executor(ioc2,
+        bindns::bind(decrement_to_zero, &ioc2, &count)));
+  ioc.restart();
+  BOOST_ASIO_CHECK(!ioc.stopped());
+  ioc.run();
 
   // No decrement_to_zero handlers can be called until run() is called on the
-  // second io_service object.
-  BOOST_ASIO_CHECK(ios.stopped());
+  // second io_context object.
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 10);
 
-  ios2.run();
+  ioc2.run();
 
   // The run() call will not return until all work has finished.
   BOOST_ASIO_CHECK(count == 0);
 
   count = 0;
   int exception_count = 0;
-  ios.reset();
-  ios.post(&throw_exception);
-  ios.post(bindns::bind(increment, &count));
-  ios.post(bindns::bind(increment, &count));
-  ios.post(&throw_exception);
-  ios.post(bindns::bind(increment, &count));
+  ioc.restart();
+  boost::asio::post(ioc, &throw_exception);
+  boost::asio::post(ioc, bindns::bind(increment, &count));
+  boost::asio::post(ioc, bindns::bind(increment, &count));
+  boost::asio::post(ioc, &throw_exception);
+  boost::asio::post(ioc, bindns::bind(increment, &count));
 
   // No handlers can be called until run() is called.
-  BOOST_ASIO_CHECK(!ios.stopped());
+  BOOST_ASIO_CHECK(!ioc.stopped());
   BOOST_ASIO_CHECK(count == 0);
   BOOST_ASIO_CHECK(exception_count == 0);
 
@@ -266,7 +269,7 @@ void io_service_test()
   {
     try
     {
-      ios.run();
+      ioc.run();
       break;
     }
     catch (int)
@@ -276,39 +279,39 @@ void io_service_test()
   }
 
   // The run() calls will not return until all work has finished.
-  BOOST_ASIO_CHECK(ios.stopped());
+  BOOST_ASIO_CHECK(ioc.stopped());
   BOOST_ASIO_CHECK(count == 3);
   BOOST_ASIO_CHECK(exception_count == 2);
 }
 
-class test_service : public boost::asio::io_service::service
+class test_service : public boost::asio::io_context::service
 {
 public:
-  static boost::asio::io_service::id id;
-  test_service(boost::asio::io_service& s)
-    : boost::asio::io_service::service(s) {}
+  static boost::asio::io_context::id id;
+  test_service(boost::asio::io_context& s)
+    : boost::asio::io_context::service(s) {}
 private:
   virtual void shutdown_service() {}
 };
 
-boost::asio::io_service::id test_service::id;
+boost::asio::io_context::id test_service::id;
 
-void io_service_service_test()
+void io_context_service_test()
 {
-  boost::asio::io_service ios1;
-  boost::asio::io_service ios2;
-  boost::asio::io_service ios3;
+  boost::asio::io_context ioc1;
+  boost::asio::io_context ioc2;
+  boost::asio::io_context ioc3;
 
   // Implicit service registration.
 
-  boost::asio::use_service<test_service>(ios1);
+  boost::asio::use_service<test_service>(ioc1);
 
-  BOOST_ASIO_CHECK(boost::asio::has_service<test_service>(ios1));
+  BOOST_ASIO_CHECK(boost::asio::has_service<test_service>(ioc1));
 
-  test_service* svc1 = new test_service(ios1);
+  test_service* svc1 = new test_service(ioc1);
   try
   {
-    boost::asio::add_service(ios1, svc1);
+    boost::asio::add_service(ioc1, svc1);
     BOOST_ASIO_ERROR("add_service did not throw");
   }
   catch (boost::asio::service_already_exists&)
@@ -318,16 +321,16 @@ void io_service_service_test()
 
   // Explicit service registration.
 
-  test_service* svc2 = new test_service(ios2);
-  boost::asio::add_service(ios2, svc2);
+  test_service* svc2 = new test_service(ioc2);
+  boost::asio::add_service(ioc2, svc2);
 
-  BOOST_ASIO_CHECK(boost::asio::has_service<test_service>(ios2));
-  BOOST_ASIO_CHECK(&boost::asio::use_service<test_service>(ios2) == svc2);
+  BOOST_ASIO_CHECK(boost::asio::has_service<test_service>(ioc2));
+  BOOST_ASIO_CHECK(&boost::asio::use_service<test_service>(ioc2) == svc2);
 
-  test_service* svc3 = new test_service(ios2);
+  test_service* svc3 = new test_service(ioc2);
   try
   {
-    boost::asio::add_service(ios2, svc3);
+    boost::asio::add_service(ioc2, svc3);
     BOOST_ASIO_ERROR("add_service did not throw");
   }
   catch (boost::asio::service_already_exists&)
@@ -337,10 +340,10 @@ void io_service_service_test()
 
   // Explicit registration with invalid owner.
 
-  test_service* svc4 = new test_service(ios2);
+  test_service* svc4 = new test_service(ioc2);
   try
   {
-    boost::asio::add_service(ios3, svc4);
+    boost::asio::add_service(ioc3, svc4);
     BOOST_ASIO_ERROR("add_service did not throw");
   }
   catch (boost::asio::invalid_service_owner&)
@@ -348,12 +351,12 @@ void io_service_service_test()
   }
   delete svc4;
 
-  BOOST_ASIO_CHECK(!boost::asio::has_service<test_service>(ios3));
+  BOOST_ASIO_CHECK(!boost::asio::has_service<test_service>(ioc3));
 }
 
 BOOST_ASIO_TEST_SUITE
 (
-  "io_service",
-  BOOST_ASIO_TEST_CASE(io_service_test)
-  BOOST_ASIO_TEST_CASE(io_service_service_test)
+  "io_context",
+  BOOST_ASIO_TEST_CASE(io_context_test)
+  BOOST_ASIO_TEST_CASE(io_context_service_test)
 )
diff --git a/test/ip/address.cpp b/test/ip/address.cpp
index d8cf8000a9..cd18b0cf41 100644
--- a/test/ip/address.cpp
+++ b/test/ip/address.cpp
@@ -69,14 +69,18 @@ void test()
     (void)addr_v6_value;
 
     std::string string_value = addr1.to_string();
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     string_value = addr1.to_string(ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // address static functions.
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     addr1 = ip::address::from_string("127.0.0.1");
     addr1 = ip::address::from_string("127.0.0.1", ec);
     addr1 = ip::address::from_string(string_value);
     addr1 = ip::address::from_string(string_value, ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // address comparisons.
 
@@ -98,6 +102,22 @@ void test()
     b = (addr1 >= addr2);
     (void)b;
 
+    // address creation functions.
+
+    addr1 = ip::make_address("127.0.0.1");
+    addr1 = ip::make_address("127.0.0.1", ec);
+    addr1 = ip::make_address(string_value);
+    addr1 = ip::make_address(string_value, ec);
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_value("127.0.0.1");
+# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::string_view string_view_value("127.0.0.1");
+# endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    addr1 = ip::make_address(string_view_value);
+    addr1 = ip::make_address(string_view_value, ec);
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
     // address I/O.
 
     std::ostringstream os;
diff --git a/test/ip/address_v4.cpp b/test/ip/address_v4.cpp
index 85d2ab5ae9..ab3770b509 100644
--- a/test/ip/address_v4.cpp
+++ b/test/ip/address_v4.cpp
@@ -53,6 +53,7 @@ void test()
     b = addr1.is_unspecified();
     (void)b;
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     b = addr1.is_class_a();
     (void)b;
 
@@ -61,6 +62,7 @@ void test()
 
     b = addr1.is_class_c();
     (void)b;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     b = addr1.is_multicast();
     (void)b;
@@ -68,18 +70,27 @@ void test()
     ip::address_v4::bytes_type bytes_value = addr1.to_bytes();
     (void)bytes_value;
 
+    ip::address_v4::uint_type uint_value = addr1.to_uint();
+    (void)uint_value;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     unsigned long ulong_value = addr1.to_ulong();
     (void)ulong_value;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     std::string string_value = addr1.to_string();
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     string_value = addr1.to_string(ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // address_v4 static functions.
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     addr1 = ip::address_v4::from_string("127.0.0.1");
     addr1 = ip::address_v4::from_string("127.0.0.1", ec);
     addr1 = ip::address_v4::from_string(string_value);
     addr1 = ip::address_v4::from_string(string_value, ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     addr1 = ip::address_v4::any();
 
@@ -87,9 +98,11 @@ void test()
 
     addr1 = ip::address_v4::broadcast();
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     addr1 = ip::address_v4::broadcast(addr2, addr3);
 
     addr1 = ip::address_v4::netmask(addr2);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // address_v4 comparisons.
 
@@ -111,6 +124,24 @@ void test()
     b = (addr1 >= addr2);
     (void)b;
 
+    // address_v4 creation functions.
+
+    addr1 = ip::make_address_v4(const_bytes_value);
+    addr1 = ip::make_address_v4(const_ulong_value);
+    addr1 = ip::make_address_v4("127.0.0.1");
+    addr1 = ip::make_address_v4("127.0.0.1", ec);
+    addr1 = ip::make_address_v4(string_value);
+    addr1 = ip::make_address_v4(string_value, ec);
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_value("127.0.0.1");
+# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::string_view string_view_value("127.0.0.1");
+# endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    addr1 = ip::make_address_v4(string_view_value);
+    addr1 = ip::make_address_v4(string_view_value, ec);
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
     // address_v4 I/O.
 
     std::ostringstream os;
@@ -146,7 +177,10 @@ void test()
   BOOST_ASIO_CHECK(a1.to_bytes()[1] == 0);
   BOOST_ASIO_CHECK(a1.to_bytes()[2] == 0);
   BOOST_ASIO_CHECK(a1.to_bytes()[3] == 0);
+  BOOST_ASIO_CHECK(a1.to_uint() == 0);
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(a1.to_ulong() == 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   address_v4::bytes_type b1 = {{ 1, 2, 3, 4 }};
   address_v4 a2(b1);
@@ -154,17 +188,26 @@ void test()
   BOOST_ASIO_CHECK(a2.to_bytes()[1] == 2);
   BOOST_ASIO_CHECK(a2.to_bytes()[2] == 3);
   BOOST_ASIO_CHECK(a2.to_bytes()[3] == 4);
+  BOOST_ASIO_CHECK(((a2.to_uint() >> 24) & 0xFF) == b1[0]);
+  BOOST_ASIO_CHECK(((a2.to_uint() >> 16) & 0xFF) == b1[1]);
+  BOOST_ASIO_CHECK(((a2.to_uint() >> 8) & 0xFF) == b1[2]);
+  BOOST_ASIO_CHECK((a2.to_uint() & 0xFF) == b1[3]);
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(((a2.to_ulong() >> 24) & 0xFF) == b1[0]);
   BOOST_ASIO_CHECK(((a2.to_ulong() >> 16) & 0xFF) == b1[1]);
   BOOST_ASIO_CHECK(((a2.to_ulong() >> 8) & 0xFF) == b1[2]);
   BOOST_ASIO_CHECK((a2.to_ulong() & 0xFF) == b1[3]);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   address_v4 a3(0x01020304);
   BOOST_ASIO_CHECK(a3.to_bytes()[0] == 1);
   BOOST_ASIO_CHECK(a3.to_bytes()[1] == 2);
   BOOST_ASIO_CHECK(a3.to_bytes()[2] == 3);
   BOOST_ASIO_CHECK(a3.to_bytes()[3] == 4);
+  BOOST_ASIO_CHECK(a3.to_uint() == 0x01020304);
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(a3.to_ulong() == 0x01020304);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   BOOST_ASIO_CHECK(address_v4(0x7F000001).is_loopback());
   BOOST_ASIO_CHECK(address_v4(0x7F000002).is_loopback());
@@ -175,6 +218,7 @@ void test()
   BOOST_ASIO_CHECK(!address_v4(0x7F000001).is_unspecified());
   BOOST_ASIO_CHECK(!address_v4(0x01020304).is_unspecified());
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(address_v4(0x01000000).is_class_a());
   BOOST_ASIO_CHECK(address_v4(0x7F000000).is_class_a());
   BOOST_ASIO_CHECK(!address_v4(0x80000000).is_class_a());
@@ -207,6 +251,7 @@ void test()
   BOOST_ASIO_CHECK(!address_v4(0xEFFFFFFF).is_class_c());
   BOOST_ASIO_CHECK(!address_v4(0xF0000000).is_class_c());
   BOOST_ASIO_CHECK(!address_v4(0xFFFFFFFF).is_class_c());
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   BOOST_ASIO_CHECK(!address_v4(0x01000000).is_multicast());
   BOOST_ASIO_CHECK(!address_v4(0x7F000000).is_multicast());
@@ -224,22 +269,32 @@ void test()
   BOOST_ASIO_CHECK(a4.to_bytes()[1] == 0);
   BOOST_ASIO_CHECK(a4.to_bytes()[2] == 0);
   BOOST_ASIO_CHECK(a4.to_bytes()[3] == 0);
+  BOOST_ASIO_CHECK(a4.to_uint() == 0);
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(a4.to_ulong() == 0);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   address_v4 a5 = address_v4::loopback();
   BOOST_ASIO_CHECK(a5.to_bytes()[0] == 0x7F);
   BOOST_ASIO_CHECK(a5.to_bytes()[1] == 0);
   BOOST_ASIO_CHECK(a5.to_bytes()[2] == 0);
   BOOST_ASIO_CHECK(a5.to_bytes()[3] == 0x01);
+  BOOST_ASIO_CHECK(a5.to_uint() == 0x7F000001);
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(a5.to_ulong() == 0x7F000001);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   address_v4 a6 = address_v4::broadcast();
   BOOST_ASIO_CHECK(a6.to_bytes()[0] == 0xFF);
   BOOST_ASIO_CHECK(a6.to_bytes()[1] == 0xFF);
   BOOST_ASIO_CHECK(a6.to_bytes()[2] == 0xFF);
   BOOST_ASIO_CHECK(a6.to_bytes()[3] == 0xFF);
+  BOOST_ASIO_CHECK(a6.to_uint() == 0xFFFFFFFF);
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(a6.to_ulong() == 0xFFFFFFFF);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   address_v4 class_a_net(0xFF000000);
   address_v4 class_b_net(0xFFFF0000);
   address_v4 class_c_net(0xFFFFFF00);
@@ -254,6 +309,7 @@ void test()
   BOOST_ASIO_CHECK(address_v4::netmask(address_v4(0xEFFFFFFF)) == other_net);
   BOOST_ASIO_CHECK(address_v4::netmask(address_v4(0xF0000000)) == other_net);
   BOOST_ASIO_CHECK(address_v4::netmask(address_v4(0xFFFFFFFF)) == other_net);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 }
 
 } // namespace ip_address_v4_runtime
diff --git a/test/ip/address_v4_iterator.cpp b/test/ip/address_v4_iterator.cpp
new file mode 100644
index 0000000000..6984694572
--- /dev/null
+++ b/test/ip/address_v4_iterator.cpp
@@ -0,0 +1,27 @@
+//
+// address_v4_iterator.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/ip/address_v4_iterator.hpp>
+
+#include "../unit_test.hpp"
+
+//------------------------------------------------------------------------------
+
+BOOST_ASIO_TEST_SUITE
+(
+  "ip/address_v4_iterator",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/ip/address_v4_range.cpp b/test/ip/address_v4_range.cpp
new file mode 100644
index 0000000000..9732e161c8
--- /dev/null
+++ b/test/ip/address_v4_range.cpp
@@ -0,0 +1,27 @@
+//
+// address_v4_range.cpp
+// ~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/ip/address_v4_range.hpp>
+
+#include "../unit_test.hpp"
+
+//------------------------------------------------------------------------------
+
+BOOST_ASIO_TEST_SUITE
+(
+  "ip/address_v4_range",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/ip/address_v6.cpp b/test/ip/address_v6.cpp
index 0cd464c999..9243f1e438 100644
--- a/test/ip/address_v6.cpp
+++ b/test/ip/address_v6.cpp
@@ -66,8 +66,10 @@ void test()
     b = addr1.is_v4_mapped();
     (void)b;
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     b = addr1.is_v4_compatible();
     (void)b;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     b = addr1.is_multicast_node_local();
     (void)b;
@@ -88,24 +90,32 @@ void test()
     (void)bytes_value;
 
     std::string string_value = addr1.to_string();
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     string_value = addr1.to_string(ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     ip::address_v4 addr3 = addr1.to_v4();
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // address_v6 static functions.
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     addr1 = ip::address_v6::from_string("0::0");
     addr1 = ip::address_v6::from_string("0::0", ec);
     addr1 = ip::address_v6::from_string(string_value);
     addr1 = ip::address_v6::from_string(string_value, ec);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     addr1 = ip::address_v6::any();
 
     addr1 = ip::address_v6::loopback();
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     addr1 = ip::address_v6::v4_mapped(addr3);
 
     addr1 = ip::address_v6::v4_compatible(addr3);
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // address_v6 comparisons.
 
@@ -127,6 +137,30 @@ void test()
     b = (addr1 >= addr2);
     (void)b;
 
+    // address_v6 creation functions.
+
+    addr1 = ip::make_address_v6(const_bytes_value, scope_id);
+    addr1 = ip::make_address_v6("0::0");
+    addr1 = ip::make_address_v6("0::0", ec);
+    addr1 = ip::make_address_v6(string_value);
+    addr1 = ip::make_address_v6(string_value, ec);
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_value("0::0");
+# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::string_view string_view_value("0::0");
+# endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    addr1 = ip::make_address_v6(string_view_value);
+    addr1 = ip::make_address_v6(string_view_value, ec);
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+    // address_v6 IPv4-mapped conversion.
+#if defined(BOOST_ASIO_NO_DEPRECATED)
+    ip::address_v4 addr3;
+#endif // defined(BOOST_ASIO_NO_DEPRECATED)
+    addr1 = ip::make_address_v6(ip::v4_mapped, addr3);
+    addr3 = ip::make_address_v4(ip::v4_mapped, addr1);
+
     // address_v6 I/O.
 
     std::ostringstream os;
@@ -274,6 +308,7 @@ void test()
   BOOST_ASIO_CHECK(!mcast_org_local_address.is_v4_mapped());
   BOOST_ASIO_CHECK(!mcast_site_local_address.is_v4_mapped());
 
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
   BOOST_ASIO_CHECK(!unspecified_address.is_v4_compatible());
   BOOST_ASIO_CHECK(!loopback_address.is_v4_compatible());
   BOOST_ASIO_CHECK(!link_local_address.is_v4_compatible());
@@ -285,6 +320,7 @@ void test()
   BOOST_ASIO_CHECK(!mcast_node_local_address.is_v4_compatible());
   BOOST_ASIO_CHECK(!mcast_org_local_address.is_v4_compatible());
   BOOST_ASIO_CHECK(!mcast_site_local_address.is_v4_compatible());
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
   BOOST_ASIO_CHECK(!unspecified_address.is_multicast());
   BOOST_ASIO_CHECK(!loopback_address.is_multicast());
diff --git a/test/ip/address_v6_iterator.cpp b/test/ip/address_v6_iterator.cpp
new file mode 100644
index 0000000000..06a201a995
--- /dev/null
+++ b/test/ip/address_v6_iterator.cpp
@@ -0,0 +1,27 @@
+//
+// address_v6_iterator.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/ip/address_v6_iterator.hpp>
+
+#include "../unit_test.hpp"
+
+//------------------------------------------------------------------------------
+
+BOOST_ASIO_TEST_SUITE
+(
+  "ip/address_v6_iterator",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/ip/address_v6_range.cpp b/test/ip/address_v6_range.cpp
new file mode 100644
index 0000000000..c6ea878a14
--- /dev/null
+++ b/test/ip/address_v6_range.cpp
@@ -0,0 +1,27 @@
+//
+// address_v6_range.cpp
+// ~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/ip/address_v6_range.hpp>
+
+#include "../unit_test.hpp"
+
+//------------------------------------------------------------------------------
+
+BOOST_ASIO_TEST_SUITE
+(
+  "ip/address_v6_range",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/ip/icmp.cpp b/test/ip/icmp.cpp
index bd563c4a34..0c5206effc 100644
--- a/test/ip/icmp.cpp
+++ b/test/ip/icmp.cpp
@@ -17,34 +17,56 @@
 #include <boost/asio/ip/icmp.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/placeholders.hpp>
 #include "../unit_test.hpp"
-#include "../archetypes/gettable_socket_option.hpp"
 #include "../archetypes/async_result.hpp"
+#include "../archetypes/deprecated_async_result.hpp"
+#include "../archetypes/gettable_socket_option.hpp"
 #include "../archetypes/io_control_command.hpp"
 #include "../archetypes/settable_socket_option.hpp"
 
 //------------------------------------------------------------------------------
 
 // ip_icmp_socket_compile test
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // The following test checks that all public member functions on the class
 // ip::icmp::socket compile and link correctly. Runtime failures are ignored.
 
 namespace ip_icmp_socket_compile {
 
-void connect_handler(const boost::system::error_code&)
+struct connect_handler
 {
-}
+  connect_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  connect_handler(connect_handler&&) {}
+private:
+  connect_handler(const connect_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void send_handler(const boost::system::error_code&, std::size_t)
+struct send_handler
 {
-}
+  send_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  send_handler(send_handler&&) {}
+private:
+  send_handler(const send_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void receive_handler(const boost::system::error_code&, std::size_t)
+struct receive_handler
 {
-}
+  receive_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  receive_handler(receive_handler&&) {}
+private:
+  receive_handler(const receive_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void test()
 {
@@ -53,7 +75,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     socket_base::message_flags in_flags = 0;
@@ -65,19 +87,22 @@ void test()
     archetypes::gettable_socket_option<double> gettable_socket_option3;
     archetypes::io_control_command io_control_command;
     archetypes::lazy_handler lazy;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    archetypes::deprecated_lazy_handler dlazy;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     boost::system::error_code ec;
 
     // basic_datagram_socket constructors.
 
-    ip::icmp::socket socket1(ios);
-    ip::icmp::socket socket2(ios, ip::icmp::v4());
-    ip::icmp::socket socket3(ios, ip::icmp::v6());
-    ip::icmp::socket socket4(ios, ip::icmp::endpoint(ip::icmp::v4(), 0));
-    ip::icmp::socket socket5(ios, ip::icmp::endpoint(ip::icmp::v6(), 0));
+    ip::icmp::socket socket1(ioc);
+    ip::icmp::socket socket2(ioc, ip::icmp::v4());
+    ip::icmp::socket socket3(ioc, ip::icmp::v6());
+    ip::icmp::socket socket4(ioc, ip::icmp::endpoint(ip::icmp::v4(), 0));
+    ip::icmp::socket socket5(ioc, ip::icmp::endpoint(ip::icmp::v6(), 0));
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
     ip::icmp::socket::native_handle_type native_socket1
       = ::socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
-    ip::icmp::socket socket6(ios, ip::icmp::v4(), native_socket1);
+    ip::icmp::socket socket6(ioc, ip::icmp::v4(), native_socket1);
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #if defined(BOOST_ASIO_HAS_MOVE)
@@ -87,14 +112,19 @@ void test()
     // basic_datagram_socket operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    socket1 = ip::icmp::socket(ios);
+    socket1 = ip::icmp::socket(ioc);
     socket1 = std::move(socket2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::icmp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
 
     // basic_socket functions.
 
@@ -126,12 +156,12 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    ip::icmp::socket::native_type native_socket4 = socket1.native();
-    (void)native_socket4;
+    socket1.release();
+    socket1.release(ec);
 
-    ip::icmp::socket::native_handle_type native_socket5
+    ip::icmp::socket::native_handle_type native_socket4
       = socket1.native_handle();
-    (void)native_socket5;
+    (void)native_socket4;
 
     socket1.cancel();
     socket1.cancel(ec);
@@ -157,13 +187,21 @@ void test()
     socket1.connect(ip::icmp::endpoint(ip::icmp::v6(), 0), ec);
 
     socket1.async_connect(ip::icmp::endpoint(ip::icmp::v4(), 0),
-        &connect_handler);
+        connect_handler());
     socket1.async_connect(ip::icmp::endpoint(ip::icmp::v6(), 0),
-        &connect_handler);
+        connect_handler());
     int i1 = socket1.async_connect(ip::icmp::endpoint(ip::icmp::v4(), 0), lazy);
     (void)i1;
     int i2 = socket1.async_connect(ip::icmp::endpoint(ip::icmp::v6(), 0), lazy);
     (void)i2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d1 = socket1.async_connect(
+        ip::icmp::endpoint(ip::icmp::v4(), 0), dlazy);
+    (void)d1;
+    double d2 = socket1.async_connect(
+        ip::icmp::endpoint(ip::icmp::v6(), 0), dlazy);
+    (void)d2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.set_option(settable_socket_option1);
     socket1.set_option(settable_socket_option1, ec);
@@ -213,12 +251,12 @@ void test()
     socket1.send(buffer(const_char_buffer), in_flags, ec);
     socket1.send(null_buffers(), in_flags, ec);
 
-    socket1.async_send(buffer(mutable_char_buffer), &send_handler);
-    socket1.async_send(buffer(const_char_buffer), &send_handler);
-    socket1.async_send(null_buffers(), &send_handler);
-    socket1.async_send(buffer(mutable_char_buffer), in_flags, &send_handler);
-    socket1.async_send(buffer(const_char_buffer), in_flags, &send_handler);
-    socket1.async_send(null_buffers(), in_flags, &send_handler);
+    socket1.async_send(buffer(mutable_char_buffer), send_handler());
+    socket1.async_send(buffer(const_char_buffer), send_handler());
+    socket1.async_send(null_buffers(), send_handler());
+    socket1.async_send(buffer(mutable_char_buffer), in_flags, send_handler());
+    socket1.async_send(buffer(const_char_buffer), in_flags, send_handler());
+    socket1.async_send(null_buffers(), in_flags, send_handler());
     int i3 = socket1.async_send(buffer(mutable_char_buffer), lazy);
     (void)i3;
     int i4 = socket1.async_send(buffer(const_char_buffer), lazy);
@@ -231,6 +269,21 @@ void test()
     (void)i7;
     int i8 = socket1.async_send(null_buffers(), in_flags, lazy);
     (void)i8;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d3 = socket1.async_send(buffer(mutable_char_buffer), dlazy);
+    (void)d3;
+    double d4 = socket1.async_send(buffer(const_char_buffer), dlazy);
+    (void)d4;
+    double d5 = socket1.async_send(null_buffers(), dlazy);
+    (void)d5;
+    double d6 = socket1.async_send(
+        buffer(mutable_char_buffer), in_flags, dlazy);
+    (void)d6;
+    double d7 = socket1.async_send(buffer(const_char_buffer), in_flags, dlazy);
+    (void)d7;
+    double d8 = socket1.async_send(null_buffers(), in_flags, dlazy);
+    (void)d8;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.send_to(buffer(mutable_char_buffer),
         ip::icmp::endpoint(ip::icmp::v4(), 0));
@@ -270,29 +323,29 @@ void test()
         ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, ec);
 
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v4(), 0), &send_handler);
+        ip::icmp::endpoint(ip::icmp::v4(), 0), send_handler());
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v6(), 0), &send_handler);
+        ip::icmp::endpoint(ip::icmp::v6(), 0), send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v4(), 0), &send_handler);
+        ip::icmp::endpoint(ip::icmp::v4(), 0), send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v6(), 0), &send_handler);
+        ip::icmp::endpoint(ip::icmp::v6(), 0), send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::icmp::endpoint(ip::icmp::v4(), 0), &send_handler);
+        ip::icmp::endpoint(ip::icmp::v4(), 0), send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::icmp::endpoint(ip::icmp::v6(), 0), &send_handler);
+        ip::icmp::endpoint(ip::icmp::v6(), 0), send_handler());
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, &send_handler);
+        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, send_handler());
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, &send_handler);
+        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, &send_handler);
+        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, &send_handler);
+        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, &send_handler);
+        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, &send_handler);
+        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, send_handler());
     int i9 = socket1.async_send_to(buffer(mutable_char_buffer),
         ip::icmp::endpoint(ip::icmp::v4(), 0), lazy);
     (void)i9;
@@ -329,6 +382,44 @@ void test()
     int i20 = socket1.async_send_to(null_buffers(),
         ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, lazy);
     (void)i20;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d9 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v4(), 0), dlazy);
+    (void)d9;
+    double d10 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v6(), 0), dlazy);
+    (void)d10;
+    double d11 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v4(), 0), dlazy);
+    (void)d11;
+    double d12 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v6(), 0), dlazy);
+    (void)d12;
+    double d13 = socket1.async_send_to(null_buffers(),
+        ip::icmp::endpoint(ip::icmp::v4(), 0), dlazy);
+    (void)d13;
+    double d14 = socket1.async_send_to(null_buffers(),
+        ip::icmp::endpoint(ip::icmp::v6(), 0), dlazy);
+    (void)d14;
+    double d15 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, dlazy);
+    (void)d15;
+    double d16 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, dlazy);
+    (void)d16;
+    double d17 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, dlazy);
+    (void)d17;
+    double d18 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, dlazy);
+    (void)d18;
+    double d19 = socket1.async_send_to(null_buffers(),
+        ip::icmp::endpoint(ip::icmp::v4(), 0), in_flags, dlazy);
+    (void)d19;
+    double d20 = socket1.async_send_to(null_buffers(),
+        ip::icmp::endpoint(ip::icmp::v6(), 0), in_flags, dlazy);
+    (void)d20;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.receive(buffer(mutable_char_buffer));
     socket1.receive(null_buffers());
@@ -337,11 +428,11 @@ void test()
     socket1.receive(buffer(mutable_char_buffer), in_flags, ec);
     socket1.receive(null_buffers(), in_flags, ec);
 
-    socket1.async_receive(buffer(mutable_char_buffer), &receive_handler);
-    socket1.async_receive(null_buffers(), &receive_handler);
+    socket1.async_receive(buffer(mutable_char_buffer), receive_handler());
+    socket1.async_receive(null_buffers(), receive_handler());
     socket1.async_receive(buffer(mutable_char_buffer), in_flags,
-        &receive_handler);
-    socket1.async_receive(null_buffers(), in_flags, &receive_handler);
+        receive_handler());
+    socket1.async_receive(null_buffers(), in_flags, receive_handler());
     int i21 = socket1.async_receive(buffer(mutable_char_buffer), lazy);
     (void)i21;
     int i22 = socket1.async_receive(null_buffers(), lazy);
@@ -351,6 +442,17 @@ void test()
     (void)i23;
     int i24 = socket1.async_receive(null_buffers(), in_flags, lazy);
     (void)i24;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d21 = socket1.async_receive(buffer(mutable_char_buffer), dlazy);
+    (void)d21;
+    double d22 = socket1.async_receive(null_buffers(), dlazy);
+    (void)d22;
+    double d23 = socket1.async_receive(buffer(mutable_char_buffer),
+        in_flags, dlazy);
+    (void)d23;
+    double d24 = socket1.async_receive(null_buffers(), in_flags, dlazy);
+    (void)d24;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     ip::icmp::endpoint endpoint;
     socket1.receive_from(buffer(mutable_char_buffer), endpoint);
@@ -361,13 +463,13 @@ void test()
     socket1.receive_from(null_buffers(), endpoint, in_flags, ec);
 
     socket1.async_receive_from(buffer(mutable_char_buffer),
-        endpoint, &receive_handler);
+        endpoint, receive_handler());
     socket1.async_receive_from(null_buffers(),
-        endpoint, &receive_handler);
+        endpoint, receive_handler());
     socket1.async_receive_from(buffer(mutable_char_buffer),
-        endpoint, in_flags, &receive_handler);
+        endpoint, in_flags, receive_handler());
     socket1.async_receive_from(null_buffers(),
-        endpoint, in_flags, &receive_handler);
+        endpoint, in_flags, receive_handler());
     int i25 = socket1.async_receive_from(buffer(mutable_char_buffer),
         endpoint, lazy);
     (void)i25;
@@ -380,6 +482,20 @@ void test()
     int i28 = socket1.async_receive_from(null_buffers(),
         endpoint, in_flags, lazy);
     (void)i28;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d25 = socket1.async_receive_from(buffer(mutable_char_buffer),
+        endpoint, dlazy);
+    (void)d25;
+    double d26 = socket1.async_receive_from(null_buffers(),
+        endpoint, dlazy);
+    (void)d26;
+    double d27 = socket1.async_receive_from(buffer(mutable_char_buffer),
+        endpoint, in_flags, dlazy);
+    (void)d27;
+    double d28 = socket1.async_receive_from(null_buffers(),
+        endpoint, in_flags, dlazy);
+    (void)d28;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
   }
   catch (std::exception&)
   {
@@ -397,10 +513,17 @@ void test()
 
 namespace ip_icmp_resolver_compile {
 
-void resolve_handler(const boost::system::error_code&,
-    boost::asio::ip::icmp::resolver::iterator)
+struct resolve_handler
 {
-}
+  resolve_handler() {}
+  void operator()(const boost::system::error_code&,
+      boost::asio::ip::icmp::resolver::results_type) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  resolve_handler(resolve_handler&&) {}
+private:
+  resolve_handler(const resolve_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void test()
 {
@@ -409,44 +532,143 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     archetypes::lazy_handler lazy;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    archetypes::deprecated_lazy_handler dlazy;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     boost::system::error_code ec;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     ip::icmp::resolver::query q(ip::icmp::v4(), "localhost", "0");
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     ip::icmp::endpoint e(ip::address_v4::loopback(), 0);
 
     // basic_resolver constructors.
 
-    ip::icmp::resolver resolver(ios);
+    ip::icmp::resolver resolver(ioc);
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    ip::icmp::resolver resolver2(std::move(resolver));
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+    // basic_resolver operators.
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    resolver = ip::icmp::resolver(ioc);
+    resolver = std::move(resolver2);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = resolver.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = resolver.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::icmp::resolver::executor_type ex = resolver.get_executor();
+    (void)ex;
 
     // basic_resolver functions.
 
     resolver.cancel();
 
-    ip::icmp::resolver::iterator iter1 = resolver.resolve(q);
-    (void)iter1;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    ip::icmp::resolver::results_type results1 = resolver.resolve(q);
+    (void)results1;
+
+    ip::icmp::resolver::results_type results2 = resolver.resolve(q, ec);
+    (void)results2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::icmp::resolver::results_type results3 = resolver.resolve("", "");
+    (void)results3;
+
+    ip::icmp::resolver::results_type results4 = resolver.resolve("", "", ec);
+    (void)results4;
 
-    ip::icmp::resolver::iterator iter2 = resolver.resolve(q, ec);
-    (void)iter2;
+    ip::icmp::resolver::results_type results5 =
+      resolver.resolve("", "", ip::icmp::resolver::flags());
+    (void)results5;
 
-    ip::icmp::resolver::iterator iter3 = resolver.resolve(e);
-    (void)iter3;
+    ip::icmp::resolver::results_type results6 =
+      resolver.resolve("", "", ip::icmp::resolver::flags(), ec);
+    (void)results6;
 
-    ip::icmp::resolver::iterator iter4 = resolver.resolve(e, ec);
-    (void)iter4;
+    ip::icmp::resolver::results_type results7 =
+      resolver.resolve(ip::icmp::v4(), "", "");
+    (void)results7;
 
-    resolver.async_resolve(q, &resolve_handler);
+    ip::icmp::resolver::results_type results8 =
+      resolver.resolve(ip::icmp::v4(), "", "", ec);
+    (void)results8;
+
+    ip::icmp::resolver::results_type results9 =
+      resolver.resolve(ip::icmp::v4(), "", "", ip::icmp::resolver::flags());
+    (void)results9;
+
+    ip::icmp::resolver::results_type results10 =
+      resolver.resolve(ip::icmp::v4(), "", "", ip::icmp::resolver::flags(), ec);
+    (void)results10;
+
+    ip::icmp::resolver::results_type results11 = resolver.resolve(e);
+    (void)results11;
+
+    ip::icmp::resolver::results_type results12 = resolver.resolve(e, ec);
+    (void)results12;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    resolver.async_resolve(q, resolve_handler());
     int i1 = resolver.async_resolve(q, lazy);
     (void)i1;
+    double d1 = resolver.async_resolve(q, dlazy);
+    (void)d1;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-    resolver.async_resolve(e, &resolve_handler);
-    int i2 = resolver.async_resolve(e, lazy);
+    resolver.async_resolve("", "", resolve_handler());
+    int i2 = resolver.async_resolve("", "", lazy);
     (void)i2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d2 = resolver.async_resolve("", "", dlazy);
+    (void)d2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve("", "",
+        ip::icmp::resolver::flags(), resolve_handler());
+    int i3 = resolver.async_resolve("", "",
+        ip::icmp::resolver::flags(), lazy);
+    (void)i3;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d3 = resolver.async_resolve("", "",
+        ip::icmp::resolver::flags(), dlazy);
+    (void)d3;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(ip::icmp::v4(), "", "", resolve_handler());
+    int i4 = resolver.async_resolve(ip::icmp::v4(), "", "", lazy);
+    (void)i4;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d4 = resolver.async_resolve(ip::icmp::v4(), "", "", dlazy);
+    (void)d4;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(ip::icmp::v4(),
+        "", "", ip::icmp::resolver::flags(), resolve_handler());
+    int i5 = resolver.async_resolve(ip::icmp::v4(),
+        "", "", ip::icmp::resolver::flags(), lazy);
+    (void)i5;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d5 = resolver.async_resolve(ip::icmp::v4(),
+        "", "", ip::icmp::resolver::flags(), dlazy);
+    (void)d5;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(e, resolve_handler());
+    int i6 = resolver.async_resolve(e, lazy);
+    (void)i6;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d6 = resolver.async_resolve(e, dlazy);
+    (void)d6;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
   }
   catch (std::exception&)
   {
diff --git a/test/ip/multicast.cpp b/test/ip/multicast.cpp
index 9982bbebac..77c2578985 100644
--- a/test/ip/multicast.cpp
+++ b/test/ip/multicast.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/ip/multicast.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include "../unit_test.hpp"
 
@@ -36,8 +36,8 @@ void test()
 
   try
   {
-    io_service ios;
-    ip::udp::socket sock(ios);
+    io_context ioc;
+    ip::udp::socket sock(ioc);
     const ip::address address;
     const ip::address_v4 address_v4;
     const ip::address_v6 address_v6;
@@ -116,17 +116,17 @@ void test()
   using namespace boost::asio;
   namespace ip = boost::asio::ip;
 
-  io_service ios;
+  io_context ioc;
   boost::system::error_code ec;
 
   ip::udp::endpoint ep_v4(ip::address_v4::loopback(), 0);
-  ip::udp::socket sock_v4(ios);
+  ip::udp::socket sock_v4(ioc);
   sock_v4.open(ep_v4.protocol(), ec);
   sock_v4.bind(ep_v4, ec);
   bool have_v4 = !ec;
 
   ip::udp::endpoint ep_v6(ip::address_v6::loopback(), 0);
-  ip::udp::socket sock_v6(ios);
+  ip::udp::socket sock_v6(ioc);
   sock_v6.open(ep_v6.protocol(), ec);
   sock_v6.bind(ep_v6, ec);
   bool have_v6 = !ec;
@@ -137,11 +137,9 @@ void test()
   // Windows CE seems to have problems with some multicast group addresses.
   // The following address works on CE, but as it is not a private multicast
   // address it will not be used on other platforms.
-  const ip::address multicast_address_v4 =
-    ip::address::from_string("239.0.0.4", ec);
+  const ip::address multicast_address_v4 = ip::make_address("239.0.0.4", ec);
 #else // defined(BOOST_ASIO_WINDOWS) && defined(UNDER_CE)
-  const ip::address multicast_address_v4 =
-    ip::address::from_string("239.255.0.1", ec);
+  const ip::address multicast_address_v4 = ip::make_address("239.255.0.1", ec);
 #endif // defined(BOOST_ASIO_WINDOWS) && defined(UNDER_CE)
   BOOST_ASIO_CHECK(!have_v4 || !ec);
 
@@ -149,14 +147,12 @@ void test()
   || defined(__FreeBSD__) \
   || defined(__NetBSD__) \
   || defined(__OpenBSD__)
-  const ip::address multicast_address_v6 =
-    ip::address::from_string("ff02::1%lo0", ec);
+  const ip::address multicast_address_v6 = ip::make_address("ff02::1%lo0", ec);
 #else // (defined(__MACH__) && defined(__APPLE__))
       //   || defined(__FreeBSD__)
       //   || defined(__NetBSD__)
       //   || defined(__OpenBSD__)
-  const ip::address multicast_address_v6 =
-    ip::address::from_string("ff01::1", ec);
+  const ip::address multicast_address_v6 = ip::make_address("ff01::1", ec);
 #endif // (defined(__MACH__) && defined(__APPLE__))
        //   || defined(__FreeBSD__)
        //   || defined(__NetBSD__)
diff --git a/test/ip/network_v4.cpp b/test/ip/network_v4.cpp
new file mode 100644
index 0000000000..24d354d7e0
--- /dev/null
+++ b/test/ip/network_v4.cpp
@@ -0,0 +1,301 @@
+//
+// network_v4.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/ip/network_v4.hpp>
+
+#include "../unit_test.hpp"
+#include <sstream>
+
+//------------------------------------------------------------------------------
+
+// ip_network_v4_compile test
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+// The following test checks that all public member functions on the class
+// ip::network_v4 compile and link correctly. Runtime failures are ignored.
+
+namespace ip_network_v4_compile {
+
+void test()
+{
+  using namespace boost::asio;
+  namespace ip = boost::asio::ip;
+
+  try
+  {
+    boost::system::error_code ec;
+
+    // network_v4 constructors.
+
+    ip::network_v4 net1(ip::make_address_v4("192.168.1.0"), 32);
+    ip::network_v4 net2(ip::make_address_v4("192.168.1.0"),
+        ip::make_address_v4("255.255.255.0"));
+
+    // network_v4 functions.
+
+    ip::address_v4 addr1 = net1.address();
+    (void)addr1;
+
+    unsigned short prefix_len = net1.prefix_length();
+    (void)prefix_len;
+
+    ip::address_v4 addr2 = net1.netmask();
+    (void)addr2;
+
+    ip::address_v4 addr3 = net1.network();
+    (void)addr3;
+
+    ip::address_v4 addr4 = net1.broadcast();
+    (void)addr4;
+
+    ip::address_v4_range hosts = net1.hosts();
+    (void)hosts;
+
+    ip::network_v4 net3 = net1.canonical();
+    (void)net3;
+
+    bool b1 = net1.is_host();
+    (void)b1;
+
+    bool b2 = net1.is_subnet_of(net2);
+    (void)b2;
+
+    std::string s1 = net1.to_string();
+    (void)s1;
+
+    std::string s2 = net1.to_string(ec);
+    (void)s2;
+
+    // network_v4 comparisons.
+
+    bool b3 = (net1 == net2);
+    (void)b3;
+
+    bool b4 = (net1 != net2);
+    (void)b4;
+
+    // network_v4 creation functions.
+
+    net1 = ip::make_network_v4(ip::address_v4(), 24);
+    net1 = ip::make_network_v4(ip::address_v4(), ip::address_v4());
+    net1 = ip::make_network_v4("10.0.0.0/8");
+    net1 = ip::make_network_v4("10.0.0.0/8", ec);
+    net1 = ip::make_network_v4(s1);
+    net1 = ip::make_network_v4(s1, ec);
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_value("10.0.0.0/8");
+# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::string_view string_view_value("10.0.0.0/8");
+# endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    net1 = ip::make_network_v4(string_view_value);
+    net1 = ip::make_network_v4(string_view_value, ec);
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+    // network_v4 I/O.
+
+    std::ostringstream os;
+    os << net1;
+
+#if !defined(BOOST_NO_STD_WSTREAMBUF)
+    std::wostringstream wos;
+    wos << net1;
+#endif // !defined(BOOST_NO_STD_WSTREAMBUF)
+  }
+  catch (std::exception&)
+  {
+  }
+}
+
+} // namespace ip_network_v4_compile
+
+//------------------------------------------------------------------------------
+
+// ip_network_v4_runtime test
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+// The following test checks that the various public member functions meet the
+// necessary postconditions.
+
+namespace ip_network_v4_runtime {
+
+void test()
+{
+  using boost::asio::ip::address_v4;
+  using boost::asio::ip::make_address_v4;
+  using boost::asio::ip::network_v4;
+  using boost::asio::ip::make_network_v4;
+
+  address_v4 addr = make_address_v4("1.2.3.4");
+
+  // calculate prefix length
+
+  network_v4 net1(addr, make_address_v4("255.255.255.0"));
+  BOOST_ASIO_CHECK(net1.prefix_length() == 24);
+
+  network_v4 net2(addr, make_address_v4("255.255.255.192"));
+  BOOST_ASIO_CHECK(net2.prefix_length() == 26);
+
+  network_v4 net3(addr, make_address_v4("128.0.0.0"));
+  BOOST_ASIO_CHECK(net3.prefix_length() == 1);
+
+  std::string msg;
+  try
+  {
+    make_network_v4(addr, make_address_v4("255.255.255.1"));
+  }
+  catch(std::exception& ex)
+  {
+    msg = ex.what();
+  }
+  BOOST_ASIO_CHECK(msg == std::string("non-contiguous netmask"));
+
+  msg.clear();
+  try
+  {
+    make_network_v4(addr, make_address_v4("0.255.255.0"));
+  }
+  catch(std::exception& ex)
+  {
+    msg = ex.what();
+  }
+  BOOST_ASIO_CHECK(msg == std::string("non-contiguous netmask"));
+
+  // calculate netmask
+
+  network_v4 net4(addr, 23);
+  BOOST_ASIO_CHECK(net4.netmask() == make_address_v4("255.255.254.0"));
+
+  network_v4 net5(addr, 12);
+  BOOST_ASIO_CHECK(net5.netmask() == make_address_v4("255.240.0.0"));
+
+  network_v4 net6(addr, 24);
+  BOOST_ASIO_CHECK(net6.netmask() == make_address_v4("255.255.255.0"));
+
+  network_v4 net7(addr, 16);
+  BOOST_ASIO_CHECK(net7.netmask() == make_address_v4("255.255.0.0"));
+
+  network_v4 net8(addr, 8);
+  BOOST_ASIO_CHECK(net8.netmask() == make_address_v4("255.0.0.0"));
+
+  network_v4 net9(addr, 32);
+  BOOST_ASIO_CHECK(net9.netmask() == make_address_v4("255.255.255.255"));
+
+  network_v4 net10(addr, 1);
+  BOOST_ASIO_CHECK(net10.netmask() == make_address_v4("128.0.0.0"));
+
+  network_v4 net11(addr, 0);
+  BOOST_ASIO_CHECK(net11.netmask() == make_address_v4("0.0.0.0"));
+
+  msg.clear();
+  try
+  {
+    make_network_v4(addr, 33);
+  }
+  catch(std::out_of_range& ex)
+  {
+    msg = ex.what();
+  }
+  BOOST_ASIO_CHECK(msg == std::string("prefix length too large"));
+
+  // construct address range from address and prefix length
+  BOOST_ASIO_CHECK(network_v4(make_address_v4("192.168.77.100"), 32).network() == make_address_v4("192.168.77.100"));
+  BOOST_ASIO_CHECK(network_v4(make_address_v4("192.168.77.100"), 24).network() == make_address_v4("192.168.77.0"));
+  BOOST_ASIO_CHECK(network_v4(make_address_v4("192.168.77.128"), 25).network() == make_address_v4("192.168.77.128"));
+
+  // construct address range from string in CIDR notation
+  BOOST_ASIO_CHECK(make_network_v4("192.168.77.100/32").network() == make_address_v4("192.168.77.100"));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.77.100/24").network() == make_address_v4("192.168.77.0"));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.77.128/25").network() == make_address_v4("192.168.77.128"));
+
+  // prefix length
+  BOOST_ASIO_CHECK(make_network_v4("193.99.144.80/24").prefix_length() == 24);
+  BOOST_ASIO_CHECK(network_v4(make_address_v4("193.99.144.80"), 24).prefix_length() == 24);
+  BOOST_ASIO_CHECK(network_v4(make_address_v4("192.168.77.0"), make_address_v4("255.255.255.0")).prefix_length() == 24);
+
+  // to string
+  std::string a("192.168.77.0/32");
+  BOOST_ASIO_CHECK(make_network_v4(a.c_str()).to_string() == a);
+  BOOST_ASIO_CHECK(network_v4(make_address_v4("192.168.77.10"), 24).to_string() == std::string("192.168.77.10/24"));
+
+  // return host part
+  BOOST_ASIO_CHECK(make_network_v4("192.168.77.11/24").address() == make_address_v4("192.168.77.11"));
+
+  // return host in CIDR notation
+  BOOST_ASIO_CHECK(make_network_v4("192.168.78.30/20").address().to_string() == "192.168.78.30");
+
+  // return network in CIDR notation
+  BOOST_ASIO_CHECK(make_network_v4("192.168.78.30/20").canonical().to_string() == "192.168.64.0/20");
+
+  // is host
+  BOOST_ASIO_CHECK(make_network_v4("192.168.77.0/32").is_host());
+  BOOST_ASIO_CHECK(!make_network_v4("192.168.77.0/31").is_host());
+
+  // is real subnet of
+  BOOST_ASIO_CHECK(make_network_v4("192.168.0.192/24").is_subnet_of(make_network_v4("192.168.0.0/16")));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.0.0/24").is_subnet_of(make_network_v4("192.168.192.168/16")));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.0.192/24").is_subnet_of(make_network_v4("192.168.192.168/16")));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.0.0/24").is_subnet_of(make_network_v4("192.168.0.0/16")));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.0.0/24").is_subnet_of(make_network_v4("192.168.0.0/23")));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.0.0/24").is_subnet_of(make_network_v4("192.168.0.0/0")));
+  BOOST_ASIO_CHECK(make_network_v4("192.168.0.0/32").is_subnet_of(make_network_v4("192.168.0.0/24")));
+
+  BOOST_ASIO_CHECK(!make_network_v4("192.168.0.0/32").is_subnet_of(make_network_v4("192.168.0.0/32")));
+  BOOST_ASIO_CHECK(!make_network_v4("192.168.0.0/24").is_subnet_of(make_network_v4("192.168.1.0/24")));
+  BOOST_ASIO_CHECK(!make_network_v4("192.168.0.0/16").is_subnet_of(make_network_v4("192.168.1.0/24")));
+
+  network_v4 r(make_network_v4("192.168.0.0/24"));
+  BOOST_ASIO_CHECK(!r.is_subnet_of(r));
+
+  network_v4 net12(make_network_v4("192.168.0.2/24"));
+  network_v4 net13(make_network_v4("192.168.1.1/28"));
+  network_v4 net14(make_network_v4("192.168.1.21/28"));
+  // network
+  BOOST_ASIO_CHECK(net12.network() == make_address_v4("192.168.0.0"));
+  BOOST_ASIO_CHECK(net13.network() == make_address_v4("192.168.1.0"));
+  BOOST_ASIO_CHECK(net14.network() == make_address_v4("192.168.1.16"));
+  // netmask
+  BOOST_ASIO_CHECK(net12.netmask() == make_address_v4("255.255.255.0"));
+  BOOST_ASIO_CHECK(net13.netmask() == make_address_v4("255.255.255.240"));
+  BOOST_ASIO_CHECK(net14.netmask() == make_address_v4("255.255.255.240"));
+  // broadcast
+  BOOST_ASIO_CHECK(net12.broadcast() == make_address_v4("192.168.0.255"));
+  BOOST_ASIO_CHECK(net13.broadcast() == make_address_v4("192.168.1.15"));
+  BOOST_ASIO_CHECK(net14.broadcast() == make_address_v4("192.168.1.31"));
+  // iterator
+  BOOST_ASIO_CHECK(std::distance(net12.hosts().begin(),net12.hosts().end()) == 254);
+  BOOST_ASIO_CHECK(*net12.hosts().begin() == make_address_v4("192.168.0.1"));
+  BOOST_ASIO_CHECK(net12.hosts().end() != net12.hosts().find(make_address_v4("192.168.0.10")));
+  BOOST_ASIO_CHECK(net12.hosts().end() == net12.hosts().find(make_address_v4("192.168.1.10")));
+  BOOST_ASIO_CHECK(std::distance(net13.hosts().begin(),net13.hosts().end()) == 14);
+  BOOST_ASIO_CHECK(*net13.hosts().begin() == make_address_v4("192.168.1.1"));
+  BOOST_ASIO_CHECK(net13.hosts().end() != net13.hosts().find(make_address_v4("192.168.1.14")));
+  BOOST_ASIO_CHECK(net13.hosts().end() == net13.hosts().find(make_address_v4("192.168.1.15")));
+  BOOST_ASIO_CHECK(std::distance(net14.hosts().begin(),net14.hosts().end()) == 14);
+  BOOST_ASIO_CHECK(*net14.hosts().begin() == make_address_v4("192.168.1.17"));
+  BOOST_ASIO_CHECK(net14.hosts().end() != net14.hosts().find(make_address_v4("192.168.1.30")));
+  BOOST_ASIO_CHECK(net14.hosts().end() == net14.hosts().find(make_address_v4("192.168.1.31")));
+}
+
+} // namespace ip_network_v4_runtime
+
+//------------------------------------------------------------------------------
+
+BOOST_ASIO_TEST_SUITE
+(
+  "ip/network_v4",
+  BOOST_ASIO_TEST_CASE(ip_network_v4_compile::test)
+  BOOST_ASIO_TEST_CASE(ip_network_v4_runtime::test)
+)
diff --git a/test/ip/network_v6.cpp b/test/ip/network_v6.cpp
new file mode 100644
index 0000000000..3b6b386a52
--- /dev/null
+++ b/test/ip/network_v6.cpp
@@ -0,0 +1,225 @@
+//
+// network_v6.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2014 Oliver Kowalke (oliver dot kowalke at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/ip/network_v6.hpp>
+
+#include "../unit_test.hpp"
+#include <sstream>
+
+//------------------------------------------------------------------------------
+
+// ip_network_v6_compile test
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+// The following test checks that all public member functions on the class
+// ip::network_v6 compile and link correctly. Runtime failures are ignored.
+
+namespace ip_network_v6_compile {
+
+void test()
+{
+  using namespace boost::asio;
+  namespace ip = boost::asio::ip;
+
+  try
+  {
+    boost::system::error_code ec;
+
+    // network_v6 constructors.
+
+    ip::network_v6 net1(ip::make_address_v6("2001:370::10:7344"), 64);
+    ip::network_v6 net2(ip::make_address_v6("2001:370::10:7345"), 96);
+
+    // network_v6 functions.
+
+    ip::address_v6 addr1 = net1.address();
+    (void)addr1;
+
+    unsigned short prefix_len = net1.prefix_length();
+    (void)prefix_len;
+
+    ip::address_v6 addr3 = net1.network();
+    (void)addr3;
+
+    ip::address_v6_range hosts = net1.hosts();
+    (void)hosts;
+
+    ip::network_v6 net3 = net1.canonical();
+    (void)net3;
+
+    bool b1 = net1.is_host();
+    (void)b1;
+
+    bool b2 = net1.is_subnet_of(net2);
+    (void)b2;
+
+    std::string s1 = net1.to_string();
+    (void)s1;
+
+    std::string s2 = net1.to_string(ec);
+    (void)s2;
+
+    // network_v6 comparisons.
+
+    bool b3 = (net1 == net2);
+    (void)b3;
+
+    bool b4 = (net1 != net2);
+    (void)b4;
+
+    // network_v6 creation functions.
+
+    net1 = ip::make_network_v6(ip::address_v6(), 24);
+    net1 = ip::make_network_v6("10.0.0.0/8");
+    net1 = ip::make_network_v6("10.0.0.0/8", ec);
+    net1 = ip::make_network_v6(s1);
+    net1 = ip::make_network_v6(s1, ec);
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_value("0::0/8");
+# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::string_view string_view_value("0::0/8");
+# endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    net1 = ip::make_network_v6(string_view_value);
+    net1 = ip::make_network_v6(string_view_value, ec);
+#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+    // network_v6 I/O.
+
+    std::ostringstream os;
+    os << net1;
+
+#if !defined(BOOST_NO_STD_WSTREAMBUF)
+    std::wostringstream wos;
+    wos << net1;
+#endif // !defined(BOOST_NO_STD_WSTREAMBUF)
+  }
+  catch (std::exception&)
+  {
+  }
+}
+
+} // namespace ip_network_v6_compile
+
+//------------------------------------------------------------------------------
+
+// ip_network_v6_runtime test
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+// The following test checks that the various public member functions meet the
+// necessary postconditions.
+
+namespace ip_network_v6_runtime {
+
+void test()
+{
+  using boost::asio::ip::address_v6;
+  using boost::asio::ip::make_address_v6;
+  using boost::asio::ip::network_v6;
+  using boost::asio::ip::make_network_v6;
+
+  address_v6 addr = make_address_v6("2001:370::10:7344");
+
+  std::string msg;
+  try
+  {
+    make_network_v6(addr, 129);
+  }
+  catch(std::out_of_range& ex)
+  {
+    msg = ex.what();
+  }
+  BOOST_ASIO_CHECK(msg == std::string("prefix length too large"));
+
+  // construct address range from address and prefix length
+  BOOST_ASIO_CHECK(network_v6(make_address_v6("2001:370::10:7344"), 128).network() == make_address_v6("2001:370::10:7344"));
+  BOOST_ASIO_CHECK(network_v6(make_address_v6("2001:370::10:7344"), 64).network() == make_address_v6("2001:370::"));
+  BOOST_ASIO_CHECK(network_v6(make_address_v6("2001:370::10:7344"), 27).network() == make_address_v6("2001:360::"));
+
+  // construct address range from string in CIDR notation
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/128").network() == make_address_v6("2001:370::10:7344"));
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/64").network() == make_address_v6("2001:370::"));
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/27").network() == make_address_v6("2001:360::"));
+
+  // prefix length
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/128").prefix_length() == 128);
+  BOOST_ASIO_CHECK(network_v6(make_address_v6("2001:370::10:7344"), 27).prefix_length() == 27);
+
+  // to string
+  std::string a("2001:370::10:7344/64");
+  BOOST_ASIO_CHECK(make_network_v6(a.c_str()).to_string() == a);
+  BOOST_ASIO_CHECK(network_v6(make_address_v6("2001:370::10:7344"), 27).to_string() == std::string("2001:370::10:7344/27"));
+
+  // return host part
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/64").address() == make_address_v6("2001:370::10:7344"));
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/27").address().to_string() == "2001:370::10:7344");
+
+  // return network in CIDR notation
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/27").canonical().to_string() == "2001:360::/27");
+
+  // is host
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:7344/128").is_host());
+  BOOST_ASIO_CHECK(!make_network_v6("2001:370::10:7344/127").is_host());
+
+  // is real subnet of
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::10:3744/64").is_subnet_of(make_network_v6("2001:370::/16")));
+  BOOST_ASIO_CHECK(make_network_v6("2001:370::/64").is_subnet_of(make_network_v6("2001:370::/16")));
+  BOOST_ASIO_CHECK(make_network_v6("2001:0db8:85a3::/64").is_subnet_of(make_network_v6("2001:0d00::/24")));
+
+  BOOST_ASIO_CHECK(!make_network_v6("2001:370::10:3744/128").is_subnet_of(make_network_v6("2001:370::10:3744/128")));
+  BOOST_ASIO_CHECK(make_network_v6("2001:0db8:85a3::/64").is_subnet_of(make_network_v6("2001:0dc0::/24")));
+
+  network_v6 r(make_network_v6("2001:370::/64"));
+  BOOST_ASIO_CHECK(!r.is_subnet_of(r));
+
+  network_v6 net12(make_network_v6("2001:370::10:7344/64"));
+  network_v6 net13(make_network_v6("2001:0db8::/127"));
+  network_v6 net14(make_network_v6("2001:0db8::/125"));
+  network_v6 net15(make_network_v6("2001:0db8::/119"));
+
+  // network
+  BOOST_ASIO_CHECK(net12.network() == make_address_v6("2001:370::"));
+  BOOST_ASIO_CHECK(net13.network() == make_address_v6("2001:0db8::"));
+  BOOST_ASIO_CHECK(net14.network() == make_address_v6("2001:0db8::"));
+  BOOST_ASIO_CHECK(net15.network() == make_address_v6("2001:0db8::"));
+
+  // iterator
+  //BOOST_ASIO_CHECK(std::distance(net12.hosts().begin(),net12.hosts().end()) == 18446744073709552000);
+  BOOST_ASIO_CHECK(std::distance(net13.hosts().begin(),net13.hosts().end()) == 2);
+  BOOST_ASIO_CHECK(std::distance(net14.hosts().begin(),net14.hosts().end()) == 8);
+  BOOST_ASIO_CHECK(std::distance(net15.hosts().begin(),net15.hosts().end()) == 512);
+  BOOST_ASIO_CHECK(*net12.hosts().begin() == make_address_v6("2001:0370::"));
+  BOOST_ASIO_CHECK(net12.hosts().end() != net12.hosts().find(make_address_v6("2001:0370::ffff:ffff:ffff:ffff")));
+  BOOST_ASIO_CHECK(*net13.hosts().begin() == make_address_v6("2001:0db8::"));
+  BOOST_ASIO_CHECK(net13.hosts().end() != net13.hosts().find(make_address_v6("2001:0db8::1")));
+  BOOST_ASIO_CHECK(net13.hosts().end() == net13.hosts().find(make_address_v6("2001:0db8::2")));
+  BOOST_ASIO_CHECK(*net14.hosts().begin() == make_address_v6("2001:0db8::"));
+  BOOST_ASIO_CHECK(net14.hosts().end() != net14.hosts().find(make_address_v6("2001:0db8::7")));
+  BOOST_ASIO_CHECK(net14.hosts().end() == net14.hosts().find(make_address_v6("2001:0db8::8")));
+  BOOST_ASIO_CHECK(*net15.hosts().begin() == make_address_v6("2001:0db8::"));
+  BOOST_ASIO_CHECK(net15.hosts().end() != net15.hosts().find(make_address_v6("2001:0db8::01ff")));
+  BOOST_ASIO_CHECK(net15.hosts().end() == net15.hosts().find(make_address_v6("2001:0db8::0200")));
+}
+
+} // namespace ip_network_v6_runtime
+
+//------------------------------------------------------------------------------
+
+BOOST_ASIO_TEST_SUITE
+(
+  "ip/network_v6",
+  BOOST_ASIO_TEST_CASE(ip_network_v6_compile::test)
+  BOOST_ASIO_TEST_CASE(ip_network_v6_runtime::test)
+)
diff --git a/test/ip/tcp.cpp b/test/ip/tcp.cpp
index ae8e5807ef..981eb96c2d 100644
--- a/test/ip/tcp.cpp
+++ b/test/ip/tcp.cpp
@@ -20,12 +20,13 @@
 #include <boost/asio/ip/tcp.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/read.hpp>
 #include <boost/asio/write.hpp>
 #include "../unit_test.hpp"
-#include "../archetypes/gettable_socket_option.hpp"
 #include "../archetypes/async_result.hpp"
+#include "../archetypes/deprecated_async_result.hpp"
+#include "../archetypes/gettable_socket_option.hpp"
 #include "../archetypes/io_control_command.hpp"
 #include "../archetypes/settable_socket_option.hpp"
 
@@ -57,8 +58,8 @@ void test()
 
   try
   {
-    io_service ios;
-    ip::tcp::socket sock(ios);
+    io_context ioc;
+    ip::tcp::socket sock(ioc);
 
     // no_delay class.
 
@@ -91,8 +92,8 @@ void test()
   using namespace boost::asio;
   namespace ip = boost::asio::ip;
 
-  io_service ios;
-  ip::tcp::socket sock(ios, ip::tcp::v4());
+  io_context ioc;
+  ip::tcp::socket sock(ioc, ip::tcp::v4());
   boost::system::error_code ec;
 
   // no_delay class.
@@ -137,25 +138,71 @@ void test()
 
 namespace ip_tcp_socket_compile {
 
-void connect_handler(const boost::system::error_code&)
+struct connect_handler
 {
-}
+  connect_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  connect_handler(connect_handler&&) {}
+private:
+  connect_handler(const connect_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void send_handler(const boost::system::error_code&, std::size_t)
+struct wait_handler
 {
-}
+  wait_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  wait_handler(wait_handler&&) {}
+private:
+  wait_handler(const wait_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void receive_handler(const boost::system::error_code&, std::size_t)
+struct send_handler
 {
-}
+  send_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  send_handler(send_handler&&) {}
+private:
+  send_handler(const send_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void write_some_handler(const boost::system::error_code&, std::size_t)
+struct receive_handler
 {
-}
+  receive_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  receive_handler(receive_handler&&) {}
+private:
+  receive_handler(const receive_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void read_some_handler(const boost::system::error_code&, std::size_t)
+struct write_some_handler
 {
-}
+  write_some_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  write_some_handler(write_some_handler&&) {}
+private:
+  write_some_handler(const write_some_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
+
+struct read_some_handler
+{
+  read_some_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  read_some_handler(read_some_handler&&) {}
+private:
+  read_some_handler(const read_some_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void test()
 {
@@ -170,7 +217,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     array<boost::asio::mutable_buffer, 2> mutable_buffers = {{
@@ -188,19 +235,22 @@ void test()
     archetypes::gettable_socket_option<double> gettable_socket_option3;
     archetypes::io_control_command io_control_command;
     archetypes::lazy_handler lazy;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    archetypes::deprecated_lazy_handler dlazy;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     boost::system::error_code ec;
 
     // basic_stream_socket constructors.
 
-    ip::tcp::socket socket1(ios);
-    ip::tcp::socket socket2(ios, ip::tcp::v4());
-    ip::tcp::socket socket3(ios, ip::tcp::v6());
-    ip::tcp::socket socket4(ios, ip::tcp::endpoint(ip::tcp::v4(), 0));
-    ip::tcp::socket socket5(ios, ip::tcp::endpoint(ip::tcp::v6(), 0));
+    ip::tcp::socket socket1(ioc);
+    ip::tcp::socket socket2(ioc, ip::tcp::v4());
+    ip::tcp::socket socket3(ioc, ip::tcp::v6());
+    ip::tcp::socket socket4(ioc, ip::tcp::endpoint(ip::tcp::v4(), 0));
+    ip::tcp::socket socket5(ioc, ip::tcp::endpoint(ip::tcp::v6(), 0));
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
     ip::tcp::socket::native_handle_type native_socket1
       = ::socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
-    ip::tcp::socket socket6(ios, ip::tcp::v4(), native_socket1);
+    ip::tcp::socket socket6(ioc, ip::tcp::v4(), native_socket1);
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #if defined(BOOST_ASIO_HAS_MOVE)
@@ -210,14 +260,19 @@ void test()
     // basic_stream_socket operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    socket1 = ip::tcp::socket(ios);
+    socket1 = ip::tcp::socket(ioc);
     socket1 = std::move(socket2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::tcp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
 
     // basic_socket functions.
 
@@ -249,12 +304,12 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    ip::tcp::socket::native_type native_socket4 = socket1.native();
-    (void)native_socket4;
+    socket1.release();
+    socket1.release(ec);
 
-    ip::tcp::socket::native_handle_type native_socket5
+    ip::tcp::socket::native_handle_type native_socket4
       = socket1.native_handle();
-    (void)native_socket5;
+    (void)native_socket4;
 
     socket1.cancel();
     socket1.cancel(ec);
@@ -280,13 +335,21 @@ void test()
     socket1.connect(ip::tcp::endpoint(ip::tcp::v6(), 0), ec);
 
     socket1.async_connect(ip::tcp::endpoint(ip::tcp::v4(), 0),
-        &connect_handler);
+        connect_handler());
     socket1.async_connect(ip::tcp::endpoint(ip::tcp::v6(), 0),
-        &connect_handler);
+        connect_handler());
     int i1 = socket1.async_connect(ip::tcp::endpoint(ip::tcp::v4(), 0), lazy);
     (void)i1;
     int i2 = socket1.async_connect(ip::tcp::endpoint(ip::tcp::v6(), 0), lazy);
     (void)i2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d1 = socket1.async_connect(
+        ip::tcp::endpoint(ip::tcp::v4(), 0), dlazy);
+    (void)d1;
+    double d2 = socket1.async_connect(
+        ip::tcp::endpoint(ip::tcp::v6(), 0), dlazy);
+    (void)d2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.set_option(settable_socket_option1);
     socket1.set_option(settable_socket_option1, ec);
@@ -324,6 +387,17 @@ void test()
     socket1.shutdown(socket_base::shutdown_both);
     socket1.shutdown(socket_base::shutdown_both, ec);
 
+    socket1.wait(socket_base::wait_read);
+    socket1.wait(socket_base::wait_write, ec);
+
+    socket1.async_wait(socket_base::wait_read, wait_handler());
+    int i3 = socket1.async_wait(socket_base::wait_write, lazy);
+    (void)i3;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d3 = socket1.async_wait(socket_base::wait_write, dlazy);
+    (void)d3;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
     // basic_stream_socket functions.
 
     socket1.send(buffer(mutable_char_buffer));
@@ -342,36 +416,59 @@ void test()
     socket1.send(const_buffers, in_flags, ec);
     socket1.send(null_buffers(), in_flags, ec);
 
-    socket1.async_send(buffer(mutable_char_buffer), &send_handler);
-    socket1.async_send(buffer(const_char_buffer), &send_handler);
-    socket1.async_send(mutable_buffers, &send_handler);
-    socket1.async_send(const_buffers, &send_handler);
-    socket1.async_send(null_buffers(), &send_handler);
-    socket1.async_send(buffer(mutable_char_buffer), in_flags, &send_handler);
-    socket1.async_send(buffer(const_char_buffer), in_flags, &send_handler);
-    socket1.async_send(mutable_buffers, in_flags, &send_handler);
-    socket1.async_send(const_buffers, in_flags, &send_handler);
-    socket1.async_send(null_buffers(), in_flags, &send_handler);
-    int i3 = socket1.async_send(buffer(mutable_char_buffer), lazy);
-    (void)i3;
-    int i4 = socket1.async_send(buffer(const_char_buffer), lazy);
+    socket1.async_send(buffer(mutable_char_buffer), send_handler());
+    socket1.async_send(buffer(const_char_buffer), send_handler());
+    socket1.async_send(mutable_buffers, send_handler());
+    socket1.async_send(const_buffers, send_handler());
+    socket1.async_send(null_buffers(), send_handler());
+    socket1.async_send(buffer(mutable_char_buffer), in_flags, send_handler());
+    socket1.async_send(buffer(const_char_buffer), in_flags, send_handler());
+    socket1.async_send(mutable_buffers, in_flags, send_handler());
+    socket1.async_send(const_buffers, in_flags, send_handler());
+    socket1.async_send(null_buffers(), in_flags, send_handler());
+    int i4 = socket1.async_send(buffer(mutable_char_buffer), lazy);
     (void)i4;
-    int i5 = socket1.async_send(mutable_buffers, lazy);
+    int i5 = socket1.async_send(buffer(const_char_buffer), lazy);
     (void)i5;
-    int i6 = socket1.async_send(const_buffers, lazy);
+    int i6 = socket1.async_send(mutable_buffers, lazy);
     (void)i6;
-    int i7 = socket1.async_send(null_buffers(), lazy);
+    int i7 = socket1.async_send(const_buffers, lazy);
     (void)i7;
-    int i8 = socket1.async_send(buffer(mutable_char_buffer), in_flags, lazy);
+    int i8 = socket1.async_send(null_buffers(), lazy);
     (void)i8;
-    int i9 = socket1.async_send(buffer(const_char_buffer), in_flags, lazy);
+    int i9 = socket1.async_send(buffer(mutable_char_buffer), in_flags, lazy);
     (void)i9;
-    int i10 = socket1.async_send(mutable_buffers, in_flags, lazy);
+    int i10 = socket1.async_send(buffer(const_char_buffer), in_flags, lazy);
     (void)i10;
-    int i11 = socket1.async_send(const_buffers, in_flags, lazy);
+    int i11 = socket1.async_send(mutable_buffers, in_flags, lazy);
     (void)i11;
-    int i12 = socket1.async_send(null_buffers(), in_flags, lazy);
+    int i12 = socket1.async_send(const_buffers, in_flags, lazy);
     (void)i12;
+    int i13 = socket1.async_send(null_buffers(), in_flags, lazy);
+    (void)i13;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d4 = socket1.async_send(buffer(mutable_char_buffer), dlazy);
+    (void)d4;
+    double d5 = socket1.async_send(buffer(const_char_buffer), dlazy);
+    (void)d5;
+    double d6 = socket1.async_send(mutable_buffers, dlazy);
+    (void)d6;
+    double d7 = socket1.async_send(const_buffers, dlazy);
+    (void)d7;
+    double d8 = socket1.async_send(null_buffers(), dlazy);
+    (void)d8;
+    double d9 = socket1.async_send(
+        buffer(mutable_char_buffer), in_flags, dlazy);
+    (void)d9;
+    double d10 = socket1.async_send(buffer(const_char_buffer), in_flags, dlazy);
+    (void)d10;
+    double d11 = socket1.async_send(mutable_buffers, in_flags, dlazy);
+    (void)d11;
+    double d12 = socket1.async_send(const_buffers, in_flags, dlazy);
+    (void)d12;
+    double d13 = socket1.async_send(null_buffers(), in_flags, dlazy);
+    (void)d13;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.receive(buffer(mutable_char_buffer));
     socket1.receive(mutable_buffers);
@@ -383,26 +480,41 @@ void test()
     socket1.receive(mutable_buffers, in_flags, ec);
     socket1.receive(null_buffers(), in_flags, ec);
 
-    socket1.async_receive(buffer(mutable_char_buffer), &receive_handler);
-    socket1.async_receive(mutable_buffers, &receive_handler);
-    socket1.async_receive(null_buffers(), &receive_handler);
+    socket1.async_receive(buffer(mutable_char_buffer), receive_handler());
+    socket1.async_receive(mutable_buffers, receive_handler());
+    socket1.async_receive(null_buffers(), receive_handler());
     socket1.async_receive(buffer(mutable_char_buffer), in_flags,
-        &receive_handler);
-    socket1.async_receive(mutable_buffers, in_flags, &receive_handler);
-    socket1.async_receive(null_buffers(), in_flags, &receive_handler);
-    int i13 = socket1.async_receive(buffer(mutable_char_buffer), lazy);
-    (void)i13;
-    int i14 = socket1.async_receive(mutable_buffers, lazy);
+        receive_handler());
+    socket1.async_receive(mutable_buffers, in_flags, receive_handler());
+    socket1.async_receive(null_buffers(), in_flags, receive_handler());
+    int i14 = socket1.async_receive(buffer(mutable_char_buffer), lazy);
     (void)i14;
-    int i15 = socket1.async_receive(null_buffers(), lazy);
+    int i15 = socket1.async_receive(mutable_buffers, lazy);
     (void)i15;
-    int i16 = socket1.async_receive(buffer(mutable_char_buffer), in_flags,
-        lazy);
+    int i16 = socket1.async_receive(null_buffers(), lazy);
     (void)i16;
-    int i17 = socket1.async_receive(mutable_buffers, in_flags, lazy);
+    int i17 = socket1.async_receive(buffer(mutable_char_buffer), in_flags,
+        lazy);
     (void)i17;
-    int i18 = socket1.async_receive(null_buffers(), in_flags, lazy);
+    int i18 = socket1.async_receive(mutable_buffers, in_flags, lazy);
     (void)i18;
+    int i19 = socket1.async_receive(null_buffers(), in_flags, lazy);
+    (void)i19;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d14 = socket1.async_receive(buffer(mutable_char_buffer), dlazy);
+    (void)d14;
+    double d15 = socket1.async_receive(mutable_buffers, dlazy);
+    (void)d15;
+    double d16 = socket1.async_receive(null_buffers(), dlazy);
+    (void)d16;
+    double d17 = socket1.async_receive(buffer(mutable_char_buffer), in_flags,
+        dlazy);
+    (void)d17;
+    double d18 = socket1.async_receive(mutable_buffers, in_flags, dlazy);
+    (void)d18;
+    double d19 = socket1.async_receive(null_buffers(), in_flags, dlazy);
+    (void)d19;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.write_some(buffer(mutable_char_buffer));
     socket1.write_some(buffer(const_char_buffer));
@@ -415,21 +527,33 @@ void test()
     socket1.write_some(const_buffers, ec);
     socket1.write_some(null_buffers(), ec);
 
-    socket1.async_write_some(buffer(mutable_char_buffer), &write_some_handler);
-    socket1.async_write_some(buffer(const_char_buffer), &write_some_handler);
-    socket1.async_write_some(mutable_buffers, &write_some_handler);
-    socket1.async_write_some(const_buffers, &write_some_handler);
-    socket1.async_write_some(null_buffers(), &write_some_handler);
-    int i19 = socket1.async_write_some(buffer(mutable_char_buffer), lazy);
-    (void)i19;
-    int i20 = socket1.async_write_some(buffer(const_char_buffer), lazy);
+    socket1.async_write_some(buffer(mutable_char_buffer), write_some_handler());
+    socket1.async_write_some(buffer(const_char_buffer), write_some_handler());
+    socket1.async_write_some(mutable_buffers, write_some_handler());
+    socket1.async_write_some(const_buffers, write_some_handler());
+    socket1.async_write_some(null_buffers(), write_some_handler());
+    int i20 = socket1.async_write_some(buffer(mutable_char_buffer), lazy);
     (void)i20;
-    int i21 = socket1.async_write_some(mutable_buffers, lazy);
+    int i21 = socket1.async_write_some(buffer(const_char_buffer), lazy);
     (void)i21;
-    int i22 = socket1.async_write_some(const_buffers, lazy);
+    int i22 = socket1.async_write_some(mutable_buffers, lazy);
     (void)i22;
-    int i23 = socket1.async_write_some(null_buffers(), lazy);
+    int i23 = socket1.async_write_some(const_buffers, lazy);
     (void)i23;
+    int i24 = socket1.async_write_some(null_buffers(), lazy);
+    (void)i24;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d20 = socket1.async_write_some(buffer(mutable_char_buffer), dlazy);
+    (void)d20;
+    double d21 = socket1.async_write_some(buffer(const_char_buffer), dlazy);
+    (void)d21;
+    double d22 = socket1.async_write_some(mutable_buffers, dlazy);
+    (void)d22;
+    double d23 = socket1.async_write_some(const_buffers, dlazy);
+    (void)d23;
+    double d24 = socket1.async_write_some(null_buffers(), dlazy);
+    (void)d24;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.read_some(buffer(mutable_char_buffer));
     socket1.read_some(mutable_buffers);
@@ -438,15 +562,23 @@ void test()
     socket1.read_some(mutable_buffers, ec);
     socket1.read_some(null_buffers(), ec);
 
-    socket1.async_read_some(buffer(mutable_char_buffer), &read_some_handler);
-    socket1.async_read_some(mutable_buffers, &read_some_handler);
-    socket1.async_read_some(null_buffers(), &read_some_handler);
-    int i24 = socket1.async_read_some(buffer(mutable_char_buffer), lazy);
-    (void)i24;
-    int i25 = socket1.async_read_some(mutable_buffers, lazy);
+    socket1.async_read_some(buffer(mutable_char_buffer), read_some_handler());
+    socket1.async_read_some(mutable_buffers, read_some_handler());
+    socket1.async_read_some(null_buffers(), read_some_handler());
+    int i25 = socket1.async_read_some(buffer(mutable_char_buffer), lazy);
     (void)i25;
-    int i26 = socket1.async_read_some(null_buffers(), lazy);
+    int i26 = socket1.async_read_some(mutable_buffers, lazy);
     (void)i26;
+    int i27 = socket1.async_read_some(null_buffers(), lazy);
+    (void)i27;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d25 = socket1.async_read_some(buffer(mutable_char_buffer), dlazy);
+    (void)d25;
+    double d26 = socket1.async_read_some(mutable_buffers, dlazy);
+    (void)d26;
+    double d27 = socket1.async_read_some(null_buffers(), dlazy);
+    (void)d27;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
   }
   catch (std::exception&)
   {
@@ -528,14 +660,14 @@ void test()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  io_service ios;
+  io_context ioc;
 
-  ip::tcp::acceptor acceptor(ios, ip::tcp::endpoint(ip::tcp::v4(), 0));
+  ip::tcp::acceptor acceptor(ioc, ip::tcp::endpoint(ip::tcp::v4(), 0));
   ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(ip::address_v4::loopback());
 
-  ip::tcp::socket client_side_socket(ios);
-  ip::tcp::socket server_side_socket(ios);
+  ip::tcp::socket client_side_socket(ioc);
+  ip::tcp::socket server_side_socket(ioc);
 
   client_side_socket.connect(server_endpoint);
   acceptor.accept(server_side_socket);
@@ -544,23 +676,23 @@ void test()
 
   bool read_noop_completed = false;
   client_side_socket.async_read_some(
-      boost::asio::mutable_buffers_1(0, 0),
+      boost::asio::mutable_buffer(0, 0),
       bindns::bind(handle_read_noop,
         _1, _2, &read_noop_completed));
 
-  ios.run();
+  ioc.run();
   BOOST_ASIO_CHECK(read_noop_completed);
 
   // No-op write.
 
   bool write_noop_completed = false;
   client_side_socket.async_write_some(
-      boost::asio::const_buffers_1(0, 0),
+      boost::asio::const_buffer(0, 0),
       bindns::bind(handle_write_noop,
         _1, _2, &write_noop_completed));
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(write_noop_completed);
 
   // Read and write to transfer data.
@@ -578,8 +710,8 @@ void test()
       bindns::bind(handle_write,
         _1, _2, &write_completed));
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(read_completed);
   BOOST_ASIO_CHECK(write_completed);
   BOOST_ASIO_CHECK(memcmp(read_buffer, write_data, sizeof(write_data)) == 0);
@@ -592,14 +724,14 @@ void test()
       bindns::bind(handle_read_cancel,
         _1, _2, &read_cancel_completed));
 
-  ios.reset();
-  ios.poll();
+  ioc.restart();
+  ioc.poll();
   BOOST_ASIO_CHECK(!read_cancel_completed);
 
   server_side_socket.cancel();
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(read_cancel_completed);
 
   // A read when the peer closes socket should fail with eof.
@@ -612,8 +744,8 @@ void test()
 
   server_side_socket.close();
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(read_eof_completed);
 }
 
@@ -628,9 +760,39 @@ void test()
 
 namespace ip_tcp_acceptor_compile {
 
-void accept_handler(const boost::system::error_code&)
+struct wait_handler
 {
-}
+  wait_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  wait_handler(wait_handler&&) {}
+private:
+  wait_handler(const wait_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
+
+struct accept_handler
+{
+  accept_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  accept_handler(accept_handler&&) {}
+private:
+  accept_handler(const accept_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+struct move_accept_handler
+{
+  move_accept_handler() {}
+  void operator()(
+      const boost::system::error_code&, boost::asio::ip::tcp::socket) {}
+  move_accept_handler(move_accept_handler&&) {}
+private:
+  move_accept_handler(const move_accept_handler&) {}
+};
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
 void test()
 {
@@ -639,8 +801,8 @@ void test()
 
   try
   {
-    io_service ios;
-    ip::tcp::socket peer_socket(ios);
+    io_context ioc;
+    ip::tcp::socket peer_socket(ioc);
     ip::tcp::endpoint peer_endpoint;
     archetypes::settable_socket_option<void> settable_socket_option1;
     archetypes::settable_socket_option<int> settable_socket_option2;
@@ -650,19 +812,22 @@ void test()
     archetypes::gettable_socket_option<double> gettable_socket_option3;
     archetypes::io_control_command io_control_command;
     archetypes::lazy_handler lazy;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    archetypes::deprecated_lazy_handler dlazy;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     boost::system::error_code ec;
 
     // basic_socket_acceptor constructors.
 
-    ip::tcp::acceptor acceptor1(ios);
-    ip::tcp::acceptor acceptor2(ios, ip::tcp::v4());
-    ip::tcp::acceptor acceptor3(ios, ip::tcp::v6());
-    ip::tcp::acceptor acceptor4(ios, ip::tcp::endpoint(ip::tcp::v4(), 0));
-    ip::tcp::acceptor acceptor5(ios, ip::tcp::endpoint(ip::tcp::v6(), 0));
+    ip::tcp::acceptor acceptor1(ioc);
+    ip::tcp::acceptor acceptor2(ioc, ip::tcp::v4());
+    ip::tcp::acceptor acceptor3(ioc, ip::tcp::v6());
+    ip::tcp::acceptor acceptor4(ioc, ip::tcp::endpoint(ip::tcp::v4(), 0));
+    ip::tcp::acceptor acceptor5(ioc, ip::tcp::endpoint(ip::tcp::v6(), 0));
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
     ip::tcp::acceptor::native_handle_type native_acceptor1
       = ::socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
-    ip::tcp::acceptor acceptor6(ios, ip::tcp::v4(), native_acceptor1);
+    ip::tcp::acceptor acceptor6(ioc, ip::tcp::v4(), native_acceptor1);
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #if defined(BOOST_ASIO_HAS_MOVE)
@@ -672,14 +837,19 @@ void test()
     // basic_socket_acceptor operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    acceptor1 = ip::tcp::acceptor(ios);
+    acceptor1 = ip::tcp::acceptor(ioc);
     acceptor1 = std::move(acceptor2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = acceptor1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = acceptor1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::tcp::acceptor::executor_type ex = acceptor1.get_executor();
+    (void)ex;
 
     // basic_socket_acceptor functions.
 
@@ -703,12 +873,12 @@ void test()
     acceptor1.close();
     acceptor1.close(ec);
 
-    ip::tcp::acceptor::native_type native_acceptor4 = acceptor1.native();
-    (void)native_acceptor4;
+    acceptor1.release();
+    acceptor1.release(ec);
 
-    ip::tcp::acceptor::native_handle_type native_acceptor5
+    ip::tcp::acceptor::native_handle_type native_acceptor4
       = acceptor1.native_handle();
-    (void)native_acceptor5;
+    (void)native_acceptor4;
 
     acceptor1.cancel();
     acceptor1.cancel(ec);
@@ -748,17 +918,49 @@ void test()
     ip::tcp::endpoint endpoint1 = acceptor1.local_endpoint();
     ip::tcp::endpoint endpoint2 = acceptor1.local_endpoint(ec);
 
+    acceptor1.wait(socket_base::wait_read);
+    acceptor1.wait(socket_base::wait_write, ec);
+
+    acceptor1.async_wait(socket_base::wait_read, wait_handler());
+    int i1 = acceptor1.async_wait(socket_base::wait_write, lazy);
+    (void)i1;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d1 = acceptor1.async_wait(socket_base::wait_write, dlazy);
+    (void)d1;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
     acceptor1.accept(peer_socket);
     acceptor1.accept(peer_socket, ec);
     acceptor1.accept(peer_socket, peer_endpoint);
     acceptor1.accept(peer_socket, peer_endpoint, ec);
 
-    acceptor1.async_accept(peer_socket, &accept_handler);
-    acceptor1.async_accept(peer_socket, peer_endpoint, &accept_handler);
-    int i1 = acceptor1.async_accept(peer_socket, lazy);
-    (void)i1;
-    int i2 = acceptor1.async_accept(peer_socket, peer_endpoint, lazy);
+#if defined(BOOST_ASIO_HAS_MOVE)
+    peer_socket = acceptor1.accept();
+    peer_socket = acceptor1.accept(ioc);
+    peer_socket = acceptor1.accept(peer_endpoint);
+    peer_socket = acceptor1.accept(ioc, peer_endpoint);
+    (void)peer_socket;
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+    acceptor1.async_accept(peer_socket, accept_handler());
+    acceptor1.async_accept(peer_socket, peer_endpoint, accept_handler());
+    int i2 = acceptor1.async_accept(peer_socket, lazy);
     (void)i2;
+    int i3 = acceptor1.async_accept(peer_socket, peer_endpoint, lazy);
+    (void)i3;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d2 = acceptor1.async_accept(peer_socket, dlazy);
+    (void)d2;
+    double d3 = acceptor1.async_accept(peer_socket, peer_endpoint, dlazy);
+    (void)d3;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    acceptor1.async_accept(move_accept_handler());
+    acceptor1.async_accept(ioc, move_accept_handler());
+    acceptor1.async_accept(peer_endpoint, move_accept_handler());
+    acceptor1.async_accept(ioc, peer_endpoint, move_accept_handler());
+#endif // defined(BOOST_ASIO_HAS_MOVE)
   }
   catch (std::exception&)
   {
@@ -791,14 +993,14 @@ void test()
   using namespace boost::asio;
   namespace ip = boost::asio::ip;
 
-  io_service ios;
+  io_context ioc;
 
-  ip::tcp::acceptor acceptor(ios, ip::tcp::endpoint(ip::tcp::v4(), 0));
+  ip::tcp::acceptor acceptor(ioc, ip::tcp::endpoint(ip::tcp::v4(), 0));
   ip::tcp::endpoint server_endpoint = acceptor.local_endpoint();
   server_endpoint.address(ip::address_v4::loopback());
 
-  ip::tcp::socket client_side_socket(ios);
-  ip::tcp::socket server_side_socket(ios);
+  ip::tcp::socket client_side_socket(ioc);
+  ip::tcp::socket server_side_socket(ioc);
 
   client_side_socket.connect(server_endpoint);
   acceptor.accept(server_side_socket);
@@ -810,9 +1012,6 @@ void test()
   ip::tcp::endpoint client_endpoint;
   acceptor.accept(server_side_socket, client_endpoint);
 
-  ip::tcp::acceptor::non_blocking_io command(false);
-  acceptor.io_control(command);
-
   ip::tcp::endpoint client_side_local_endpoint
     = client_side_socket.local_endpoint();
   BOOST_ASIO_CHECK(client_side_local_endpoint.port() == client_endpoint.port());
@@ -828,7 +1027,7 @@ void test()
   acceptor.async_accept(server_side_socket, &handle_accept);
   client_side_socket.async_connect(server_endpoint, &handle_connect);
 
-  ios.run();
+  ioc.run();
 
   client_side_socket.close();
   server_side_socket.close();
@@ -836,8 +1035,8 @@ void test()
   acceptor.async_accept(server_side_socket, client_endpoint, &handle_accept);
   client_side_socket.async_connect(server_endpoint, &handle_connect);
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   client_side_local_endpoint = client_side_socket.local_endpoint();
   BOOST_ASIO_CHECK(client_side_local_endpoint.port() == client_endpoint.port());
@@ -858,10 +1057,17 @@ void test()
 
 namespace ip_tcp_resolver_compile {
 
-void resolve_handler(const boost::system::error_code&,
-    boost::asio::ip::tcp::resolver::iterator)
+struct resolve_handler
 {
-}
+  resolve_handler() {}
+  void operator()(const boost::system::error_code&,
+      boost::asio::ip::tcp::resolver::results_type) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  resolve_handler(resolve_handler&&) {}
+private:
+  resolve_handler(const resolve_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void test()
 {
@@ -870,44 +1076,143 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     archetypes::lazy_handler lazy;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    archetypes::deprecated_lazy_handler dlazy;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     boost::system::error_code ec;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     ip::tcp::resolver::query q(ip::tcp::v4(), "localhost", "0");
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     ip::tcp::endpoint e(ip::address_v4::loopback(), 0);
 
     // basic_resolver constructors.
 
-    ip::tcp::resolver resolver(ios);
+    ip::tcp::resolver resolver(ioc);
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    ip::tcp::resolver resolver2(std::move(resolver));
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+    // basic_resolver operators.
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    resolver = ip::tcp::resolver(ioc);
+    resolver = std::move(resolver2);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = resolver.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = resolver.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::tcp::resolver::executor_type ex = resolver.get_executor();
+    (void)ex;
 
     // basic_resolver functions.
 
     resolver.cancel();
 
-    ip::tcp::resolver::iterator iter1 = resolver.resolve(q);
-    (void)iter1;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    ip::tcp::resolver::results_type results1 = resolver.resolve(q);
+    (void)results1;
+
+    ip::tcp::resolver::results_type results2 = resolver.resolve(q, ec);
+    (void)results2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-    ip::tcp::resolver::iterator iter2 = resolver.resolve(q, ec);
-    (void)iter2;
+    ip::tcp::resolver::results_type results3 = resolver.resolve("", "");
+    (void)results3;
 
-    ip::tcp::resolver::iterator iter3 = resolver.resolve(e);
-    (void)iter3;
+    ip::tcp::resolver::results_type results4 = resolver.resolve("", "", ec);
+    (void)results4;
 
-    ip::tcp::resolver::iterator iter4 = resolver.resolve(e, ec);
-    (void)iter4;
+    ip::tcp::resolver::results_type results5 =
+      resolver.resolve("", "", ip::tcp::resolver::flags());
+    (void)results5;
 
-    resolver.async_resolve(q, &resolve_handler);
+    ip::tcp::resolver::results_type results6 =
+      resolver.resolve("", "", ip::tcp::resolver::flags(), ec);
+    (void)results6;
+
+    ip::tcp::resolver::results_type results7 =
+      resolver.resolve(ip::tcp::v4(), "", "");
+    (void)results7;
+
+    ip::tcp::resolver::results_type results8 =
+      resolver.resolve(ip::tcp::v4(), "", "", ec);
+    (void)results8;
+
+    ip::tcp::resolver::results_type results9 =
+      resolver.resolve(ip::tcp::v4(), "", "", ip::tcp::resolver::flags());
+    (void)results9;
+
+    ip::tcp::resolver::results_type results10 =
+      resolver.resolve(ip::tcp::v4(), "", "", ip::tcp::resolver::flags(), ec);
+    (void)results10;
+
+    ip::tcp::resolver::results_type results11 = resolver.resolve(e);
+    (void)results11;
+
+    ip::tcp::resolver::results_type results12 = resolver.resolve(e, ec);
+    (void)results12;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    resolver.async_resolve(q, resolve_handler());
     int i1 = resolver.async_resolve(q, lazy);
     (void)i1;
+    double d1 = resolver.async_resolve(q, dlazy);
+    (void)d1;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-    resolver.async_resolve(e, &resolve_handler);
-    int i2 = resolver.async_resolve(e, lazy);
+    resolver.async_resolve("", "", resolve_handler());
+    int i2 = resolver.async_resolve("", "", lazy);
     (void)i2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d2 = resolver.async_resolve("", "", dlazy);
+    (void)d2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve("", "",
+        ip::tcp::resolver::flags(), resolve_handler());
+    int i3 = resolver.async_resolve("", "",
+        ip::tcp::resolver::flags(), lazy);
+    (void)i3;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d3 = resolver.async_resolve("", "",
+        ip::tcp::resolver::flags(), dlazy);
+    (void)d3;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(ip::tcp::v4(), "", "", resolve_handler());
+    int i4 = resolver.async_resolve(ip::tcp::v4(), "", "", lazy);
+    (void)i4;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d4 = resolver.async_resolve(ip::tcp::v4(), "", "", dlazy);
+    (void)d4;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(ip::tcp::v4(),
+        "", "", ip::tcp::resolver::flags(), resolve_handler());
+    int i5 = resolver.async_resolve(ip::tcp::v4(),
+        "", "", ip::tcp::resolver::flags(), lazy);
+    (void)i5;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d5 = resolver.async_resolve(ip::tcp::v4(),
+        "", "", ip::tcp::resolver::flags(), dlazy);
+    (void)d5;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(e, resolve_handler());
+    int i6 = resolver.async_resolve(e, lazy);
+    (void)i6;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d6 = resolver.async_resolve(e, dlazy);
+    (void)d6;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
   }
   catch (std::exception&)
   {
@@ -918,6 +1223,145 @@ void test()
 
 //------------------------------------------------------------------------------
 
+// ip_tcp_resolver_entry_compile test
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// The following test checks that all public member functions on the class
+// ip::tcp::resolver::entry compile and link correctly. Runtime failures are
+// ignored.
+
+namespace ip_tcp_resolver_entry_compile {
+
+void test()
+{
+  using namespace boost::asio;
+  namespace ip = boost::asio::ip;
+  const ip::tcp::endpoint endpoint;
+  const std::string host_name;
+  const std::string service_name;
+  const std::allocator<char> alloc;
+
+  try
+  {
+    // basic_resolver_entry constructors.
+
+    const ip::basic_resolver_entry<ip::tcp> entry1;
+    ip::basic_resolver_entry<ip::tcp> entry2(endpoint, host_name, service_name);
+    ip::basic_resolver_entry<ip::tcp> entry3(entry1);
+#if defined(BOOST_ASIO_HAS_MOVE)
+    ip::basic_resolver_entry<ip::tcp> entry4(std::move(entry2));
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+    // basic_resolver_entry functions.
+
+    ip::tcp::endpoint e1 = entry1.endpoint();
+    (void)e1;
+
+    ip::tcp::endpoint e2 = entry1;
+    (void)e2;
+
+    std::string s1 = entry1.host_name();
+    (void)s1;
+
+    std::string s2 = entry1.host_name(alloc);
+    (void)s2;
+
+    std::string s3 = entry1.service_name();
+    (void)s3;
+
+    std::string s4 = entry1.service_name(alloc);
+    (void)s4;
+  }
+  catch (std::exception&)
+  {
+  }
+}
+
+} // namespace ip_tcp_resolver_entry_compile
+
+//------------------------------------------------------------------------------
+
+// ip_tcp_iostream_compile test
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// The following test checks that all public types and member functions on the
+// class ip::tcp::iostream compile and link correctly. Runtime failures are
+// ignored.
+
+namespace ip_tcp_iostream_compile {
+
+void test()
+{
+#if !defined(BOOST_ASIO_NO_IOSTREAM)
+  using namespace boost::asio;
+  namespace ip = boost::asio::ip;
+
+  boost::asio::io_context ioc;
+  boost::asio::ip::tcp::socket sock(ioc);
+
+  // basic_socket_iostream typedefs.
+
+  (void)static_cast<ip::tcp::iostream::protocol_type*>(0);
+  (void)static_cast<ip::tcp::iostream::endpoint_type*>(0);
+  (void)static_cast<ip::tcp::iostream::clock_type*>(0);
+  (void)static_cast<ip::tcp::iostream::time_point*>(0);
+  (void)static_cast<ip::tcp::iostream::duration*>(0);
+  (void)static_cast<ip::tcp::iostream::traits_type*>(0);
+
+  // basic_socket_iostream constructors.
+
+  ip::tcp::iostream ios1;
+
+#if defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)
+  ip::tcp::iostream ios2(std::move(sock));
+#endif // defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)
+
+  ip::tcp::iostream ios3("hostname", "service");
+
+  // basic_socket_iostream operators.
+
+#if defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)
+  ios1 = ip::tcp::iostream();
+
+  ios2 = std::move(ios1);
+#endif // defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)
+
+  // basic_socket_iostream members.
+
+  ios1.connect("hostname", "service");
+
+  ios1.close();
+
+  (void)static_cast<std::streambuf*>(ios1.rdbuf());
+
+#if defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  basic_socket<ip::tcp, stream_socket_service<ip::tcp> >& sref = ios1.socket();
+#else // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  basic_socket<ip::tcp>& sref = ios1.socket();
+#endif // defined(BOOST_ASIO_ENABLE_OLD_SERVICES)
+  (void)sref;
+
+  boost::system::error_code ec = ios1.error();
+  (void)ec;
+
+  ip::tcp::iostream::time_point tp = ios1.expiry();
+  (void)tp;
+
+  ios1.expires_at(tp);
+
+  ip::tcp::iostream::duration d;
+  ios1.expires_after(d);
+
+  // iostream operators.
+
+  int i = 0;
+  ios1 >> i;
+  ios1 << i;
+#endif // !defined(BOOST_ASIO_NO_IOSTREAM)
+}
+
+} // namespace ip_tcp_iostream_compile
+
+//------------------------------------------------------------------------------
+
 BOOST_ASIO_TEST_SUITE
 (
   "ip/tcp",
@@ -928,4 +1372,7 @@ BOOST_ASIO_TEST_SUITE
   BOOST_ASIO_TEST_CASE(ip_tcp_acceptor_compile::test)
   BOOST_ASIO_TEST_CASE(ip_tcp_acceptor_runtime::test)
   BOOST_ASIO_TEST_CASE(ip_tcp_resolver_compile::test)
+  BOOST_ASIO_TEST_CASE(ip_tcp_resolver_entry_compile::test)
+  BOOST_ASIO_TEST_CASE(ip_tcp_resolver_entry_compile::test)
+  BOOST_ASIO_COMPILE_TEST_CASE(ip_tcp_iostream_compile::test)
 )
diff --git a/test/ip/udp.cpp b/test/ip/udp.cpp
index 620f81a80a..c413681e32 100644
--- a/test/ip/udp.cpp
+++ b/test/ip/udp.cpp
@@ -17,10 +17,11 @@
 #include <boost/asio/ip/udp.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../unit_test.hpp"
-#include "../archetypes/gettable_socket_option.hpp"
 #include "../archetypes/async_result.hpp"
+#include "../archetypes/deprecated_async_result.hpp"
+#include "../archetypes/gettable_socket_option.hpp"
 #include "../archetypes/io_control_command.hpp"
 #include "../archetypes/settable_socket_option.hpp"
 
@@ -39,17 +40,49 @@
 
 namespace ip_udp_socket_compile {
 
-void connect_handler(const boost::system::error_code&)
+struct connect_handler
 {
-}
+  connect_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  connect_handler(connect_handler&&) {}
+private:
+  connect_handler(const connect_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void send_handler(const boost::system::error_code&, std::size_t)
+struct wait_handler
 {
-}
+  wait_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  wait_handler(wait_handler&&) {}
+private:
+  wait_handler(const wait_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void receive_handler(const boost::system::error_code&, std::size_t)
+struct send_handler
 {
-}
+  send_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  send_handler(send_handler&&) {}
+private:
+  send_handler(const send_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
+
+struct receive_handler
+{
+  receive_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  receive_handler(receive_handler&&) {}
+private:
+  receive_handler(const receive_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void test()
 {
@@ -58,7 +91,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     socket_base::message_flags in_flags = 0;
@@ -70,19 +103,22 @@ void test()
     archetypes::gettable_socket_option<double> gettable_socket_option3;
     archetypes::io_control_command io_control_command;
     archetypes::lazy_handler lazy;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    archetypes::deprecated_lazy_handler dlazy;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     boost::system::error_code ec;
 
     // basic_datagram_socket constructors.
 
-    ip::udp::socket socket1(ios);
-    ip::udp::socket socket2(ios, ip::udp::v4());
-    ip::udp::socket socket3(ios, ip::udp::v6());
-    ip::udp::socket socket4(ios, ip::udp::endpoint(ip::udp::v4(), 0));
-    ip::udp::socket socket5(ios, ip::udp::endpoint(ip::udp::v6(), 0));
+    ip::udp::socket socket1(ioc);
+    ip::udp::socket socket2(ioc, ip::udp::v4());
+    ip::udp::socket socket3(ioc, ip::udp::v6());
+    ip::udp::socket socket4(ioc, ip::udp::endpoint(ip::udp::v4(), 0));
+    ip::udp::socket socket5(ioc, ip::udp::endpoint(ip::udp::v6(), 0));
 #if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
     ip::udp::socket::native_handle_type native_socket1
       = ::socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
-    ip::udp::socket socket6(ios, ip::udp::v4(), native_socket1);
+    ip::udp::socket socket6(ioc, ip::udp::v4(), native_socket1);
 #endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
 #if defined(BOOST_ASIO_HAS_MOVE)
@@ -92,14 +128,19 @@ void test()
     // basic_datagram_socket operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    socket1 = ip::udp::socket(ios);
+    socket1 = ip::udp::socket(ioc);
     socket1 = std::move(socket2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::udp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
 
     // basic_socket functions.
 
@@ -131,12 +172,12 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    ip::udp::socket::native_type native_socket4 = socket1.native();
-    (void)native_socket4;
+    socket1.release();
+    socket1.release(ec);
 
-    ip::udp::socket::native_handle_type native_socket5
+    ip::udp::socket::native_handle_type native_socket4
       = socket1.native_handle();
-    (void)native_socket5;
+    (void)native_socket4;
 
     socket1.cancel();
     socket1.cancel(ec);
@@ -162,13 +203,21 @@ void test()
     socket1.connect(ip::udp::endpoint(ip::udp::v6(), 0), ec);
 
     socket1.async_connect(ip::udp::endpoint(ip::udp::v4(), 0),
-        &connect_handler);
+        connect_handler());
     socket1.async_connect(ip::udp::endpoint(ip::udp::v6(), 0),
-        &connect_handler);
+        connect_handler());
     int i1 = socket1.async_connect(ip::udp::endpoint(ip::udp::v4(), 0), lazy);
     (void)i1;
     int i2 = socket1.async_connect(ip::udp::endpoint(ip::udp::v6(), 0), lazy);
     (void)i2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d1 = socket1.async_connect(
+        ip::udp::endpoint(ip::udp::v4(), 0), dlazy);
+    (void)d1;
+    double d2 = socket1.async_connect(
+        ip::udp::endpoint(ip::udp::v6(), 0), dlazy);
+    (void)d2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.set_option(settable_socket_option1);
     socket1.set_option(settable_socket_option1, ec);
@@ -206,6 +255,17 @@ void test()
     socket1.shutdown(socket_base::shutdown_both);
     socket1.shutdown(socket_base::shutdown_both, ec);
 
+    socket1.wait(socket_base::wait_read);
+    socket1.wait(socket_base::wait_write, ec);
+
+    socket1.async_wait(socket_base::wait_read, wait_handler());
+    int i3 = socket1.async_wait(socket_base::wait_write, lazy);
+    (void)i3;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d3 = socket1.async_wait(socket_base::wait_write, dlazy);
+    (void)d3;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
     // basic_datagram_socket functions.
 
     socket1.send(buffer(mutable_char_buffer));
@@ -218,24 +278,39 @@ void test()
     socket1.send(buffer(const_char_buffer), in_flags, ec);
     socket1.send(null_buffers(), in_flags, ec);
 
-    socket1.async_send(buffer(mutable_char_buffer), &send_handler);
-    socket1.async_send(buffer(const_char_buffer), &send_handler);
-    socket1.async_send(null_buffers(), &send_handler);
-    socket1.async_send(buffer(mutable_char_buffer), in_flags, &send_handler);
-    socket1.async_send(buffer(const_char_buffer), in_flags, &send_handler);
-    socket1.async_send(null_buffers(), in_flags, &send_handler);
-    int i3 = socket1.async_send(buffer(mutable_char_buffer), lazy);
-    (void)i3;
-    int i4 = socket1.async_send(buffer(const_char_buffer), lazy);
+    socket1.async_send(buffer(mutable_char_buffer), send_handler());
+    socket1.async_send(buffer(const_char_buffer), send_handler());
+    socket1.async_send(null_buffers(), send_handler());
+    socket1.async_send(buffer(mutable_char_buffer), in_flags, send_handler());
+    socket1.async_send(buffer(const_char_buffer), in_flags, send_handler());
+    socket1.async_send(null_buffers(), in_flags, send_handler());
+    int i4 = socket1.async_send(buffer(mutable_char_buffer), lazy);
     (void)i4;
-    int i5 = socket1.async_send(null_buffers(), lazy);
+    int i5 = socket1.async_send(buffer(const_char_buffer), lazy);
     (void)i5;
-    int i6 = socket1.async_send(buffer(mutable_char_buffer), in_flags, lazy);
+    int i6 = socket1.async_send(null_buffers(), lazy);
     (void)i6;
-    int i7 = socket1.async_send(buffer(const_char_buffer), in_flags, lazy);
+    int i7 = socket1.async_send(buffer(mutable_char_buffer), in_flags, lazy);
     (void)i7;
-    int i8 = socket1.async_send(null_buffers(), in_flags, lazy);
+    int i8 = socket1.async_send(buffer(const_char_buffer), in_flags, lazy);
     (void)i8;
+    int i9 = socket1.async_send(null_buffers(), in_flags, lazy);
+    (void)i9;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d4 = socket1.async_send(buffer(mutable_char_buffer), dlazy);
+    (void)d4;
+    double d5 = socket1.async_send(buffer(const_char_buffer), dlazy);
+    (void)d5;
+    double d6 = socket1.async_send(null_buffers(), dlazy);
+    (void)d6;
+    double d7 = socket1.async_send(
+        buffer(mutable_char_buffer), in_flags, dlazy);
+    (void)d7;
+    double d8 = socket1.async_send(buffer(const_char_buffer), in_flags, dlazy);
+    (void)d8;
+    double d9 = socket1.async_send(null_buffers(), in_flags, dlazy);
+    (void)d9;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.send_to(buffer(mutable_char_buffer),
         ip::udp::endpoint(ip::udp::v4(), 0));
@@ -275,65 +350,103 @@ void test()
         ip::udp::endpoint(ip::udp::v6(), 0), in_flags, ec);
 
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v4(), 0), &send_handler);
+        ip::udp::endpoint(ip::udp::v4(), 0), send_handler());
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), &send_handler);
+        ip::udp::endpoint(ip::udp::v6(), 0), send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::udp::endpoint(ip::udp::v4(), 0), &send_handler);
+        ip::udp::endpoint(ip::udp::v4(), 0), send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), &send_handler);
+        ip::udp::endpoint(ip::udp::v6(), 0), send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::udp::endpoint(ip::udp::v4(), 0), &send_handler);
+        ip::udp::endpoint(ip::udp::v4(), 0), send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::udp::endpoint(ip::udp::v6(), 0), &send_handler);
+        ip::udp::endpoint(ip::udp::v6(), 0), send_handler());
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, &send_handler);
+        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, send_handler());
     socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, &send_handler);
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, &send_handler);
+        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, send_handler());
     socket1.async_send_to(buffer(const_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, &send_handler);
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, &send_handler);
+        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, send_handler());
     socket1.async_send_to(null_buffers(),
-        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, &send_handler);
-    int i9 = socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v4(), 0), lazy);
-    (void)i9;
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, send_handler());
     int i10 = socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), lazy);
-    (void)i10;
-    int i11 = socket1.async_send_to(buffer(const_char_buffer),
         ip::udp::endpoint(ip::udp::v4(), 0), lazy);
+    (void)i10;
+    int i11 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), lazy);
     (void)i11;
     int i12 = socket1.async_send_to(buffer(const_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), lazy);
-    (void)i12;
-    int i13 = socket1.async_send_to(null_buffers(),
         ip::udp::endpoint(ip::udp::v4(), 0), lazy);
+    (void)i12;
+    int i13 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), lazy);
     (void)i13;
     int i14 = socket1.async_send_to(null_buffers(),
-        ip::udp::endpoint(ip::udp::v6(), 0), lazy);
+        ip::udp::endpoint(ip::udp::v4(), 0), lazy);
     (void)i14;
-    int i15 = socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, lazy);
+    int i15 = socket1.async_send_to(null_buffers(),
+        ip::udp::endpoint(ip::udp::v6(), 0), lazy);
     (void)i15;
     int i16 = socket1.async_send_to(buffer(mutable_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, lazy);
-    (void)i16;
-    int i17 = socket1.async_send_to(buffer(const_char_buffer),
         ip::udp::endpoint(ip::udp::v4(), 0), in_flags, lazy);
+    (void)i16;
+    int i17 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, lazy);
     (void)i17;
     int i18 = socket1.async_send_to(buffer(const_char_buffer),
-        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, lazy);
-    (void)i18;
-    int i19 = socket1.async_send_to(null_buffers(),
         ip::udp::endpoint(ip::udp::v4(), 0), in_flags, lazy);
+    (void)i18;
+    int i19 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, lazy);
     (void)i19;
     int i20 = socket1.async_send_to(null_buffers(),
-        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, lazy);
+        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, lazy);
     (void)i20;
+    int i21 = socket1.async_send_to(null_buffers(),
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, lazy);
+    (void)i21;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d10 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::udp::endpoint(ip::udp::v4(), 0), dlazy);
+    (void)d10;
+    double d11 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), dlazy);
+    (void)d11;
+    double d12 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::udp::endpoint(ip::udp::v4(), 0), dlazy);
+    (void)d12;
+    double d13 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), dlazy);
+    (void)d13;
+    double d14 = socket1.async_send_to(null_buffers(),
+        ip::udp::endpoint(ip::udp::v4(), 0), dlazy);
+    (void)d14;
+    double d15 = socket1.async_send_to(null_buffers(),
+        ip::udp::endpoint(ip::udp::v6(), 0), dlazy);
+    (void)d15;
+    double d16 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, dlazy);
+    (void)d16;
+    double d17 = socket1.async_send_to(buffer(mutable_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, dlazy);
+    (void)d17;
+    double d18 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, dlazy);
+    (void)d18;
+    double d19 = socket1.async_send_to(buffer(const_char_buffer),
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, dlazy);
+    (void)d19;
+    double d20 = socket1.async_send_to(null_buffers(),
+        ip::udp::endpoint(ip::udp::v4(), 0), in_flags, dlazy);
+    (void)d20;
+    double d21 = socket1.async_send_to(null_buffers(),
+        ip::udp::endpoint(ip::udp::v6(), 0), in_flags, dlazy);
+    (void)d21;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     socket1.receive(buffer(mutable_char_buffer));
     socket1.receive(null_buffers());
@@ -342,20 +455,31 @@ void test()
     socket1.receive(buffer(mutable_char_buffer), in_flags, ec);
     socket1.receive(null_buffers(), in_flags, ec);
 
-    socket1.async_receive(buffer(mutable_char_buffer), &receive_handler);
-    socket1.async_receive(null_buffers(), &receive_handler);
+    socket1.async_receive(buffer(mutable_char_buffer), receive_handler());
+    socket1.async_receive(null_buffers(), receive_handler());
     socket1.async_receive(buffer(mutable_char_buffer), in_flags,
-        &receive_handler);
-    socket1.async_receive(null_buffers(), in_flags, &receive_handler);
-    int i21 = socket1.async_receive(buffer(mutable_char_buffer), lazy);
-    (void)i21;
-    int i22 = socket1.async_receive(null_buffers(), lazy);
+        receive_handler());
+    socket1.async_receive(null_buffers(), in_flags, receive_handler());
+    int i22 = socket1.async_receive(buffer(mutable_char_buffer), lazy);
     (void)i22;
-    int i23 = socket1.async_receive(buffer(mutable_char_buffer),
-        in_flags, lazy);
+    int i23 = socket1.async_receive(null_buffers(), lazy);
     (void)i23;
-    int i24 = socket1.async_receive(null_buffers(), in_flags, lazy);
+    int i24 = socket1.async_receive(buffer(mutable_char_buffer),
+        in_flags, lazy);
     (void)i24;
+    int i25 = socket1.async_receive(null_buffers(), in_flags, lazy);
+    (void)i25;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d22 = socket1.async_receive(buffer(mutable_char_buffer), dlazy);
+    (void)d22;
+    double d23 = socket1.async_receive(null_buffers(), dlazy);
+    (void)d23;
+    double d24 = socket1.async_receive(buffer(mutable_char_buffer),
+        in_flags, dlazy);
+    (void)d24;
+    double d25 = socket1.async_receive(null_buffers(), in_flags, dlazy);
+    (void)d25;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     ip::udp::endpoint endpoint;
     socket1.receive_from(buffer(mutable_char_buffer), endpoint);
@@ -366,25 +490,39 @@ void test()
     socket1.receive_from(null_buffers(), endpoint, in_flags, ec);
 
     socket1.async_receive_from(buffer(mutable_char_buffer),
-        endpoint, &receive_handler);
+        endpoint, receive_handler());
     socket1.async_receive_from(null_buffers(),
-        endpoint, &receive_handler);
+        endpoint, receive_handler());
     socket1.async_receive_from(buffer(mutable_char_buffer),
-        endpoint, in_flags, &receive_handler);
+        endpoint, in_flags, receive_handler());
     socket1.async_receive_from(null_buffers(),
-        endpoint, in_flags, &receive_handler);
-    int i25 = socket1.async_receive_from(buffer(mutable_char_buffer),
-        endpoint, lazy);
-    (void)i25;
-    int i26 = socket1.async_receive_from(null_buffers(),
+        endpoint, in_flags, receive_handler());
+    int i26 = socket1.async_receive_from(buffer(mutable_char_buffer),
         endpoint, lazy);
     (void)i26;
-    int i27 = socket1.async_receive_from(buffer(mutable_char_buffer),
-        endpoint, in_flags, lazy);
+    int i27 = socket1.async_receive_from(null_buffers(),
+        endpoint, lazy);
     (void)i27;
-    int i28 = socket1.async_receive_from(null_buffers(),
+    int i28 = socket1.async_receive_from(buffer(mutable_char_buffer),
         endpoint, in_flags, lazy);
     (void)i28;
+    int i29 = socket1.async_receive_from(null_buffers(),
+        endpoint, in_flags, lazy);
+    (void)i29;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d26 = socket1.async_receive_from(buffer(mutable_char_buffer),
+        endpoint, dlazy);
+    (void)d26;
+    double d27 = socket1.async_receive_from(null_buffers(),
+        endpoint, dlazy);
+    (void)d27;
+    double d28 = socket1.async_receive_from(buffer(mutable_char_buffer),
+        endpoint, in_flags, dlazy);
+    (void)d28;
+    double d29 = socket1.async_receive_from(null_buffers(),
+        endpoint, in_flags, dlazy);
+    (void)d29;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
   }
   catch (std::exception&)
   {
@@ -429,13 +567,13 @@ void test()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  io_service ios;
+  io_context ioc;
 
-  ip::udp::socket s1(ios, ip::udp::endpoint(ip::udp::v4(), 0));
+  ip::udp::socket s1(ioc, ip::udp::endpoint(ip::udp::v4(), 0));
   ip::udp::endpoint target_endpoint = s1.local_endpoint();
   target_endpoint.address(ip::address_v4::loopback());
 
-  ip::udp::socket s2(ios);
+  ip::udp::socket s2(ioc);
   s2.open(ip::udp::v4());
   s2.bind(ip::udp::endpoint(ip::udp::v4(), 0));
   char send_msg[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
@@ -457,7 +595,7 @@ void test()
   s2.async_receive_from(buffer(recv_msg, sizeof(recv_msg)), sender_endpoint,
       bindns::bind(handle_recv, sizeof(recv_msg), _1, _2));
 
-  ios.run();
+  ioc.run();
 
   BOOST_ASIO_CHECK(memcmp(send_msg, recv_msg, sizeof(send_msg)) == 0);
 }
@@ -473,10 +611,17 @@ void test()
 
 namespace ip_udp_resolver_compile {
 
-void resolve_handler(const boost::system::error_code&,
-    boost::asio::ip::udp::resolver::iterator)
+struct resolve_handler
 {
-}
+  resolve_handler() {}
+  void operator()(const boost::system::error_code&,
+      boost::asio::ip::udp::resolver::results_type) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  resolve_handler(resolve_handler&&) {}
+private:
+  resolve_handler(const resolve_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void test()
 {
@@ -485,44 +630,143 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     archetypes::lazy_handler lazy;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    archetypes::deprecated_lazy_handler dlazy;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     boost::system::error_code ec;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
     ip::udp::resolver::query q(ip::udp::v4(), "localhost", "0");
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
     ip::udp::endpoint e(ip::address_v4::loopback(), 0);
 
     // basic_resolver constructors.
 
-    ip::udp::resolver resolver(ios);
+    ip::udp::resolver resolver(ioc);
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    ip::udp::resolver resolver2(std::move(resolver));
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+
+    // basic_resolver operators.
+
+#if defined(BOOST_ASIO_HAS_MOVE)
+    resolver = ip::udp::resolver(ioc);
+    resolver = std::move(resolver2);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = resolver.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = resolver.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::udp::resolver::executor_type ex = resolver.get_executor();
+    (void)ex;
 
     // basic_resolver functions.
 
     resolver.cancel();
 
-    ip::udp::resolver::iterator iter1 = resolver.resolve(q);
-    (void)iter1;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    ip::udp::resolver::results_type results1 = resolver.resolve(q);
+    (void)results1;
+
+    ip::udp::resolver::results_type results2 = resolver.resolve(q, ec);
+    (void)results2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    ip::udp::resolver::results_type results3 = resolver.resolve("", "");
+    (void)results3;
 
-    ip::udp::resolver::iterator iter2 = resolver.resolve(q, ec);
-    (void)iter2;
+    ip::udp::resolver::results_type results4 = resolver.resolve("", "", ec);
+    (void)results4;
 
-    ip::udp::resolver::iterator iter3 = resolver.resolve(e);
-    (void)iter3;
+    ip::udp::resolver::results_type results5 =
+      resolver.resolve("", "", ip::udp::resolver::flags());
+    (void)results5;
 
-    ip::udp::resolver::iterator iter4 = resolver.resolve(e, ec);
-    (void)iter4;
+    ip::udp::resolver::results_type results6 =
+      resolver.resolve("", "", ip::udp::resolver::flags(), ec);
+    (void)results6;
 
-    resolver.async_resolve(q, &resolve_handler);
+    ip::udp::resolver::results_type results7 =
+      resolver.resolve(ip::udp::v4(), "", "");
+    (void)results7;
+
+    ip::udp::resolver::results_type results8 =
+      resolver.resolve(ip::udp::v4(), "", "", ec);
+    (void)results8;
+
+    ip::udp::resolver::results_type results9 =
+      resolver.resolve(ip::udp::v4(), "", "", ip::udp::resolver::flags());
+    (void)results9;
+
+    ip::udp::resolver::results_type results10 =
+      resolver.resolve(ip::udp::v4(), "", "", ip::udp::resolver::flags(), ec);
+    (void)results10;
+
+    ip::udp::resolver::results_type results11 = resolver.resolve(e);
+    (void)results11;
+
+    ip::udp::resolver::results_type results12 = resolver.resolve(e, ec);
+    (void)results12;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    resolver.async_resolve(q, resolve_handler());
     int i1 = resolver.async_resolve(q, lazy);
     (void)i1;
+    double d1 = resolver.async_resolve(q, dlazy);
+    (void)d1;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
-    resolver.async_resolve(e, &resolve_handler);
-    int i2 = resolver.async_resolve(e, lazy);
+    resolver.async_resolve("", "", resolve_handler());
+    int i2 = resolver.async_resolve("", "", lazy);
     (void)i2;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d2 = resolver.async_resolve("", "", dlazy);
+    (void)d2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve("", "",
+        ip::udp::resolver::flags(), resolve_handler());
+    int i3 = resolver.async_resolve("", "",
+        ip::udp::resolver::flags(), lazy);
+    (void)i3;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d3 = resolver.async_resolve("", "",
+        ip::udp::resolver::flags(), dlazy);
+    (void)d3;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(ip::udp::v4(), "", "", resolve_handler());
+    int i4 = resolver.async_resolve(ip::udp::v4(), "", "", lazy);
+    (void)i4;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d4 = resolver.async_resolve(ip::udp::v4(), "", "", dlazy);
+    (void)d4;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(ip::udp::v4(),
+        "", "", ip::udp::resolver::flags(), resolve_handler());
+    int i5 = resolver.async_resolve(ip::udp::v4(),
+        "", "", ip::udp::resolver::flags(), lazy);
+    (void)i5;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d5 = resolver.async_resolve(ip::udp::v4(),
+        "", "", ip::udp::resolver::flags(), dlazy);
+    (void)d5;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    resolver.async_resolve(e, resolve_handler());
+    int i6 = resolver.async_resolve(e, lazy);
+    (void)i6;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    double d6 = resolver.async_resolve(e, dlazy);
+    (void)d6;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
   }
   catch (std::exception&)
   {
diff --git a/test/ip/unicast.cpp b/test/ip/unicast.cpp
index 47d88abe46..ad66d0cd7a 100644
--- a/test/ip/unicast.cpp
+++ b/test/ip/unicast.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/ip/unicast.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include "../unit_test.hpp"
 
@@ -36,8 +36,8 @@ void test()
 
   try
   {
-    io_service ios;
-    ip::udp::socket sock(ios);
+    io_context ioc;
+    ip::udp::socket sock(ioc);
 
     // hops class.
 
@@ -69,17 +69,17 @@ void test()
   using namespace boost::asio;
   namespace ip = boost::asio::ip;
 
-  io_service ios;
+  io_context ioc;
   boost::system::error_code ec;
 
   ip::udp::endpoint ep_v4(ip::address_v4::loopback(), 0);
-  ip::udp::socket sock_v4(ios);
+  ip::udp::socket sock_v4(ioc);
   sock_v4.open(ep_v4.protocol(), ec);
   sock_v4.bind(ep_v4, ec);
   bool have_v4 = !ec;
 
   ip::udp::endpoint ep_v6(ip::address_v6::loopback(), 0);
-  ip::udp::socket sock_v6(ios);
+  ip::udp::socket sock_v6(ioc);
   sock_v6.open(ep_v6.protocol(), ec);
   sock_v6.bind(ep_v6, ec);
   bool have_v6 = !ec;
diff --git a/test/ip/v6_only.cpp b/test/ip/v6_only.cpp
index a94b580575..1486190d55 100644
--- a/test/ip/v6_only.cpp
+++ b/test/ip/v6_only.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/ip/v6_only.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include "../unit_test.hpp"
@@ -37,8 +37,8 @@ void test()
 
   try
   {
-    io_service ios;
-    ip::udp::socket sock(ios);
+    io_context ioc;
+    ip::udp::socket sock(ioc);
 
     // v6_only class.
 
@@ -72,11 +72,11 @@ void test()
   using namespace boost::asio;
   namespace ip = boost::asio::ip;
 
-  io_service ios;
+  io_context ioc;
   boost::system::error_code ec;
 
   ip::tcp::endpoint ep_v6(ip::address_v6::loopback(), 0);
-  ip::tcp::acceptor acceptor_v6(ios);
+  ip::tcp::acceptor acceptor_v6(ioc);
   acceptor_v6.open(ep_v6.protocol(), ec);
   acceptor_v6.bind(ep_v6, ec);
   bool have_v6 = !ec;
diff --git a/test/is_read_buffered.cpp b/test/is_read_buffered.cpp
index a73f40a84a..6d345d755f 100644
--- a/test/is_read_buffered.cpp
+++ b/test/is_read_buffered.cpp
@@ -18,7 +18,7 @@
 
 #include <boost/asio/buffered_read_stream.hpp>
 #include <boost/asio/buffered_write_stream.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include "unit_test.hpp"
 
@@ -27,18 +27,20 @@ using namespace std; // For memcmp, memcpy and memset.
 class test_stream
 {
 public:
-  typedef boost::asio::io_service io_service_type;
+  typedef boost::asio::io_context io_context_type;
 
   typedef test_stream lowest_layer_type;
 
-  test_stream(boost::asio::io_service& io_service)
-    : io_service_(io_service)
+  typedef io_context_type::executor_type executor_type;
+
+  test_stream(boost::asio::io_context& io_context)
+    : io_context_(io_context)
   {
   }
 
-  io_service_type& io_service()
+  io_context_type& io_context()
   {
-    return io_service_;
+    return io_context_;
   }
 
   lowest_layer_type& lowest_layer()
@@ -63,7 +65,8 @@ class test_stream
   void async_write(const Const_Buffers&, Handler handler)
   {
     boost::system::error_code error;
-    io_service_.post(boost::asio::detail::bind_handler(handler, error, 0));
+    boost::asio::post(io_context_,
+        boost::asio::detail::bind_handler(handler, error, 0));
   }
 
   template <typename Mutable_Buffers>
@@ -83,11 +86,12 @@ class test_stream
   void async_read(const Mutable_Buffers&, Handler handler)
   {
     boost::system::error_code error;
-    io_service_.post(boost::asio::detail::bind_handler(handler, error, 0));
+    boost::asio::post(io_context_,
+        boost::asio::detail::bind_handler(handler, error, 0));
   }
 
 private:
-  io_service_type& io_service_;
+  io_context_type& io_context_;
 };
 
 void is_read_buffered_test()
diff --git a/test/is_write_buffered.cpp b/test/is_write_buffered.cpp
index 1a48ca04a6..69122e2dc9 100644
--- a/test/is_write_buffered.cpp
+++ b/test/is_write_buffered.cpp
@@ -18,7 +18,7 @@
 
 #include <boost/asio/buffered_read_stream.hpp>
 #include <boost/asio/buffered_write_stream.hpp>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include "unit_test.hpp"
 
@@ -27,18 +27,20 @@ using namespace std; // For memcmp, memcpy and memset.
 class test_stream
 {
 public:
-  typedef boost::asio::io_service io_service_type;
+  typedef boost::asio::io_context io_context_type;
 
   typedef test_stream lowest_layer_type;
 
-  test_stream(boost::asio::io_service& io_service)
-    : io_service_(io_service)
+  typedef io_context_type::executor_type executor_type;
+
+  test_stream(boost::asio::io_context& io_context)
+    : io_context_(io_context)
   {
   }
 
-  io_service_type& io_service()
+  io_context_type& io_context()
   {
-    return io_service_;
+    return io_context_;
   }
 
   lowest_layer_type& lowest_layer()
@@ -63,7 +65,8 @@ class test_stream
   void async_write(const Const_Buffers&, Handler handler)
   {
     boost::system::error_code error;
-    io_service_.post(boost::asio::detail::bind_handler(handler, error, 0));
+    boost::asio::post(io_context_,
+        boost::asio::detail::bind_handler(handler, error, 0));
   }
 
   template <typename Mutable_Buffers>
@@ -83,11 +86,12 @@ class test_stream
   void async_read(const Mutable_Buffers&, Handler handler)
   {
     boost::system::error_code error;
-    io_service_.post(boost::asio::detail::bind_handler(handler, error, 0));
+    boost::asio::post(io_context_,
+        boost::asio::detail::bind_handler(handler, error, 0));
   }
 
 private:
-  io_service_type& io_service_;
+  io_context_type& io_context_;
 };
 
 void is_write_buffered_test()
diff --git a/test/latency/tcp_client.cpp b/test/latency/tcp_client.cpp
index 0978f78ba8..8779810af2 100644
--- a/test/latency/tcp_client.cpp
+++ b/test/latency/tcp_client.cpp
@@ -50,22 +50,21 @@ int main(int argc, char* argv[])
   std::size_t buf_size = static_cast<std::size_t>(std::atoi(argv[4]));
   bool spin = (std::strcmp(argv[5], "spin") == 0);
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
   std::vector<boost::shared_ptr<tcp::socket> > sockets;
 
   for (int i = 0; i < num_connections; ++i)
   {
-    boost::shared_ptr<tcp::socket> s(new tcp::socket(io_service));
+    boost::shared_ptr<tcp::socket> s(new tcp::socket(io_context));
 
-    tcp::endpoint target(boost::asio::ip::address::from_string(ip), port);
+    tcp::endpoint target(boost::asio::ip::make_address(ip), port);
     s->connect(target);
 
     s->set_option(tcp::no_delay(true));
 
     if (spin)
     {
-      tcp::socket::non_blocking_io nbio(true);
-      s->io_control(nbio);
+      s->non_blocking(true);
     }
 
     sockets.push_back(s);
diff --git a/test/latency/tcp_server.cpp b/test/latency/tcp_server.cpp
index 51b30bee50..c461ded5e8 100644
--- a/test/latency/tcp_server.cpp
+++ b/test/latency/tcp_server.cpp
@@ -8,7 +8,7 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/read.hpp>
 #include <boost/asio/write.hpp>
@@ -27,7 +27,7 @@ class tcp_server : coroutine
 public:
   tcp_server(tcp::acceptor& acceptor, std::size_t buf_size) :
     acceptor_(acceptor),
-    socket_(acceptor_.get_io_service()),
+    socket_(acceptor_.get_executor().context()),
     buffer_(buf_size)
   {
   }
@@ -96,8 +96,8 @@ int main(int argc, char* argv[])
   std::size_t buf_size = std::atoi(argv[3]);
   bool spin = (std::strcmp(argv[4], "spin") == 0);
 
-  boost::asio::io_service io_service(1);
-  tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), port));
+  boost::asio::io_context io_context(1);
+  tcp::acceptor acceptor(io_context, tcp::endpoint(tcp::v4(), port));
   std::vector<boost::shared_ptr<tcp_server> > servers;
 
   for (int i = 0; i < max_connections; ++i)
@@ -108,7 +108,7 @@ int main(int argc, char* argv[])
   }
 
   if (spin)
-    for (;;) io_service.poll();
+    for (;;) io_context.poll();
   else
-    io_service.run();
+    io_context.run();
 }
diff --git a/test/latency/udp_client.cpp b/test/latency/udp_client.cpp
index e3dcbf9b7a..62f4817f68 100644
--- a/test/latency/udp_client.cpp
+++ b/test/latency/udp_client.cpp
@@ -39,17 +39,16 @@ int main(int argc, char* argv[])
   std::size_t buf_size = static_cast<std::size_t>(std::atoi(argv[4]));
   bool spin = (std::strcmp(argv[5], "spin") == 0);
 
-  boost::asio::io_service io_service;
+  boost::asio::io_context io_context;
 
-  udp::socket socket(io_service, udp::endpoint(udp::v4(), 0));
+  udp::socket socket(io_context, udp::endpoint(udp::v4(), 0));
 
   if (spin)
   {
-    udp::socket::non_blocking_io nbio(true);
-    socket.io_control(nbio);
+    socket.non_blocking(true);
   }
 
-  udp::endpoint target(boost::asio::ip::address::from_string(ip), first_port);
+  udp::endpoint target(boost::asio::ip::make_address(ip), first_port);
   unsigned short last_port = first_port + num_ports - 1;
   std::vector<unsigned char> write_buf(buf_size);
   std::vector<unsigned char> read_buf(buf_size);
diff --git a/test/latency/udp_server.cpp b/test/latency/udp_server.cpp
index 81b186ddef..407872027e 100644
--- a/test/latency/udp_server.cpp
+++ b/test/latency/udp_server.cpp
@@ -8,7 +8,7 @@
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include <boost/shared_ptr.hpp>
 #include <cstdio>
@@ -24,9 +24,9 @@ using boost::asio::ip::udp;
 class udp_server : coroutine
 {
 public:
-  udp_server(boost::asio::io_service& io_service,
+  udp_server(boost::asio::io_context& io_context,
       unsigned short port, std::size_t buf_size) :
-    socket_(io_service, udp::endpoint(udp::v4(), port)),
+    socket_(io_context, udp::endpoint(udp::v4(), port)),
     buffer_(buf_size)
   {
   }
@@ -107,19 +107,19 @@ int main(int argc, char* argv[])
   std::size_t buf_size = std::atoi(argv[3]);
   bool spin = (std::strcmp(argv[4], "spin") == 0);
 
-  boost::asio::io_service io_service(1);
+  boost::asio::io_context io_context(1);
   std::vector<boost::shared_ptr<udp_server> > servers;
 
   for (unsigned short i = 0; i < num_ports; ++i)
   {
     unsigned short port = first_port + i;
-    boost::shared_ptr<udp_server> s(new udp_server(io_service, port, buf_size));
+    boost::shared_ptr<udp_server> s(new udp_server(io_context, port, buf_size));
     servers.push_back(s);
     (*s)(boost::system::error_code());
   }
 
   if (spin)
-    for (;;) io_service.poll();
+    for (;;) io_context.poll();
   else
-    io_service.run();
+    io_context.run();
 }
diff --git a/test/local/connect_pair.cpp b/test/local/connect_pair.cpp
index b3b04643c1..e36c48fff4 100644
--- a/test/local/connect_pair.cpp
+++ b/test/local/connect_pair.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/local/connect_pair.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/local/datagram_protocol.hpp>
 #include <boost/asio/local/stream_protocol.hpp>
 #include "../unit_test.hpp"
@@ -40,25 +40,24 @@ void test()
 
   try
   {
-    boost::asio::io_service io_service;
+    boost::asio::io_context io_context;
     boost::system::error_code ec1;
-    boost::system::error_code ec2;
 
-    dp::socket s1(io_service);
-    dp::socket s2(io_service);
+    dp::socket s1(io_context);
+    dp::socket s2(io_context);
     local::connect_pair(s1, s2);
 
-    dp::socket s3(io_service);
-    dp::socket s4(io_service);
-    ec1 = local::connect_pair(s3, s4, ec2);
+    dp::socket s3(io_context);
+    dp::socket s4(io_context);
+    local::connect_pair(s3, s4, ec1);
 
-    sp::socket s5(io_service);
-    sp::socket s6(io_service);
+    sp::socket s5(io_context);
+    sp::socket s6(io_context);
     local::connect_pair(s5, s6);
 
-    sp::socket s7(io_service);
-    sp::socket s8(io_service);
-    ec1 = local::connect_pair(s7, s8, ec2);
+    sp::socket s7(io_context);
+    sp::socket s8(io_context);
+    local::connect_pair(s7, s8, ec1);
   }
   catch (std::exception&)
   {
diff --git a/test/local/datagram_protocol.cpp b/test/local/datagram_protocol.cpp
index a6172f13f2..20ceac8cc6 100644
--- a/test/local/datagram_protocol.cpp
+++ b/test/local/datagram_protocol.cpp
@@ -17,7 +17,7 @@
 #include <boost/asio/local/datagram_protocol.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../unit_test.hpp"
 
 //------------------------------------------------------------------------------
@@ -51,7 +51,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     socket_base::message_flags in_flags = 0;
@@ -61,16 +61,21 @@ void test()
 
     // basic_datagram_socket constructors.
 
-    dp::socket socket1(ios);
-    dp::socket socket2(ios, dp());
-    dp::socket socket3(ios, dp::endpoint(""));
+    dp::socket socket1(ioc);
+    dp::socket socket2(ioc, dp());
+    dp::socket socket3(ioc, dp::endpoint(""));
     int native_socket1 = ::socket(AF_UNIX, SOCK_DGRAM, 0);
-    dp::socket socket4(ios, dp(), native_socket1);
+    dp::socket socket4(ioc, dp(), native_socket1);
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    dp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
 
     // basic_socket functions.
 
@@ -91,7 +96,7 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    dp::socket::native_type native_socket4 = socket1.native();
+    dp::socket::native_handle_type native_socket4 = socket1.native_handle();
     (void)native_socket4;
 
     socket1.cancel();
diff --git a/test/local/stream_protocol.cpp b/test/local/stream_protocol.cpp
index f19858b89a..7be5ae4ce6 100644
--- a/test/local/stream_protocol.cpp
+++ b/test/local/stream_protocol.cpp
@@ -17,7 +17,7 @@
 #include <boost/asio/local/stream_protocol.hpp>
 
 #include <cstring>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../unit_test.hpp"
 
 //------------------------------------------------------------------------------
@@ -59,7 +59,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     socket_base::message_flags in_flags = 0;
@@ -69,16 +69,21 @@ void test()
 
     // basic_stream_socket constructors.
 
-    sp::socket socket1(ios);
-    sp::socket socket2(ios, sp());
-    sp::socket socket3(ios, sp::endpoint(""));
+    sp::socket socket1(ioc);
+    sp::socket socket2(ioc, sp());
+    sp::socket socket3(ioc, sp::endpoint(""));
     int native_socket1 = ::socket(AF_UNIX, SOCK_STREAM, 0);
-    sp::socket socket4(ios, sp(), native_socket1);
+    sp::socket socket4(ioc, sp(), native_socket1);
 
     // basic_io_object functions.
 
-    io_service& ios_ref = socket1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = socket1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    sp::socket::executor_type ex = socket1.get_executor();
+    (void)ex;
 
     // basic_socket functions.
 
@@ -99,7 +104,7 @@ void test()
     socket1.close();
     socket1.close(ec);
 
-    sp::socket::native_type native_socket4 = socket1.native();
+    sp::socket::native_handle_type native_socket4 = socket1.native_handle();
     (void)native_socket4;
 
     socket1.cancel();
diff --git a/test/packaged_task.cpp b/test/packaged_task.cpp
new file mode 100644
index 0000000000..4a0b6481c3
--- /dev/null
+++ b/test/packaged_task.cpp
@@ -0,0 +1,25 @@
+//
+// packaged_task.cpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/packaged_task.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "packaged_task",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/ssl/basic_context.cpp b/test/posix/descriptor.cpp
similarity index 82%
rename from test/ssl/basic_context.cpp
rename to test/posix/descriptor.cpp
index 4da4c22aeb..683c477635 100644
--- a/test/ssl/basic_context.cpp
+++ b/test/posix/descriptor.cpp
@@ -1,6 +1,6 @@
 //
-// basic_context.cpp
-// ~~~~~~~~~~~~~~~~~
+// descriptor.cpp
+// ~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
@@ -14,12 +14,12 @@
 #endif // !defined(BOOST_ALL_NO_LIB)
 
 // Test that header file is self-contained.
-#include <boost/asio/ssl/basic_context.hpp>
+#include <boost/asio/posix/descriptor.hpp>
 
 #include "../unit_test.hpp"
 
 BOOST_ASIO_TEST_SUITE
 (
-  "ssl/basic_context",
+  "posix/descriptor",
   BOOST_ASIO_TEST_CASE(null_test)
 )
diff --git a/test/posix/stream_descriptor.cpp b/test/posix/stream_descriptor.cpp
index 625b20b41f..0a70679cf7 100644
--- a/test/posix/stream_descriptor.cpp
+++ b/test/posix/stream_descriptor.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/posix/stream_descriptor.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../archetypes/async_result.hpp"
 #include "../unit_test.hpp"
 
@@ -30,6 +30,10 @@
 
 namespace posix_stream_descriptor_compile {
 
+void wait_handler(const boost::system::error_code&)
+{
+}
+
 void write_some_handler(const boost::system::error_code&, std::size_t)
 {
 }
@@ -46,7 +50,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     posix::descriptor_base::bytes_readable io_control_command;
@@ -55,25 +59,30 @@ void test()
 
     // basic_stream_descriptor constructors.
 
-    posix::stream_descriptor descriptor1(ios);
+    posix::stream_descriptor descriptor1(ioc);
     int native_descriptor1 = -1;
-    posix::stream_descriptor descriptor2(ios, native_descriptor1);
+    posix::stream_descriptor descriptor2(ioc, native_descriptor1);
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    posix::stream_descriptor descriptor3(std::move(descriptor3));
+    posix::stream_descriptor descriptor3(std::move(descriptor2));
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_stream_descriptor operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    descriptor1 = posix::stream_descriptor(ios);
+    descriptor1 = posix::stream_descriptor(ioc);
     descriptor1 = std::move(descriptor2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = descriptor1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = descriptor1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    posix::stream_descriptor::executor_type ex = descriptor1.get_executor();
+    (void)ex;
 
     // basic_descriptor functions.
 
@@ -95,17 +104,13 @@ void test()
     descriptor1.close();
     descriptor1.close(ec);
 
-    posix::stream_descriptor::native_type native_descriptor3
-      = descriptor1.native();
+    posix::stream_descriptor::native_handle_type native_descriptor3
+      = descriptor1.native_handle();
     (void)native_descriptor3;
 
     posix::stream_descriptor::native_handle_type native_descriptor4
-      = descriptor1.native_handle();
-    (void)native_descriptor4;
-
-    posix::stream_descriptor::native_handle_type native_descriptor5
       = descriptor1.release();
-    (void)native_descriptor5;
+    (void)native_descriptor4;
 
     descriptor1.cancel();
     descriptor1.cancel(ec);
@@ -123,6 +128,13 @@ void test()
     descriptor1.native_non_blocking(true);
     descriptor1.native_non_blocking(false, ec);
 
+    descriptor1.wait(posix::descriptor_base::wait_read);
+    descriptor1.wait(posix::descriptor_base::wait_write, ec);
+
+    descriptor1.async_wait(posix::descriptor_base::wait_read, &wait_handler);
+    int i1 = descriptor1.async_wait(posix::descriptor_base::wait_write, lazy);
+    (void)i1;
+
     // basic_stream_descriptor functions.
 
     descriptor1.write_some(buffer(mutable_char_buffer));
@@ -138,12 +150,12 @@ void test()
         write_some_handler);
     descriptor1.async_write_some(null_buffers(),
         write_some_handler);
-    int i1 = descriptor1.async_write_some(buffer(mutable_char_buffer), lazy);
-    (void)i1;
-    int i2 = descriptor1.async_write_some(buffer(const_char_buffer), lazy);
+    int i2 = descriptor1.async_write_some(buffer(mutable_char_buffer), lazy);
     (void)i2;
-    int i3 = descriptor1.async_write_some(null_buffers(), lazy);
+    int i3 = descriptor1.async_write_some(buffer(const_char_buffer), lazy);
     (void)i3;
+    int i4 = descriptor1.async_write_some(null_buffers(), lazy);
+    (void)i4;
 
     descriptor1.read_some(buffer(mutable_char_buffer));
     descriptor1.read_some(buffer(mutable_char_buffer), ec);
@@ -151,10 +163,10 @@ void test()
 
     descriptor1.async_read_some(buffer(mutable_char_buffer), read_some_handler);
     descriptor1.async_read_some(null_buffers(), read_some_handler);
-    int i4 = descriptor1.async_read_some(buffer(mutable_char_buffer), lazy);
-    (void)i4;
-    int i5 = descriptor1.async_read_some(null_buffers(), lazy);
+    int i5 = descriptor1.async_read_some(buffer(mutable_char_buffer), lazy);
     (void)i5;
+    int i6 = descriptor1.async_read_some(null_buffers(), lazy);
+    (void)i6;
   }
   catch (std::exception&)
   {
diff --git a/test/post.cpp b/test/post.cpp
new file mode 100644
index 0000000000..913d8de3ed
--- /dev/null
+++ b/test/post.cpp
@@ -0,0 +1,25 @@
+//
+// post.cpp
+// ~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/post.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "post",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/read.cpp b/test/read.cpp
index a77143d87d..4a7a3570c7 100644
--- a/test/read.cpp
+++ b/test/read.cpp
@@ -19,7 +19,8 @@
 #include <cstring>
 #include <vector>
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/streambuf.hpp>
 #include "unit_test.hpp"
 
@@ -42,19 +43,19 @@ using namespace std; // For memcmp, memcpy and memset.
 class test_stream
 {
 public:
-  typedef boost::asio::io_service io_service_type;
+  typedef boost::asio::io_context::executor_type executor_type;
 
-  test_stream(boost::asio::io_service& io_service)
-    : io_service_(io_service),
+  test_stream(boost::asio::io_context& io_context)
+    : io_context_(io_context),
       length_(0),
       position_(0),
       next_read_length_(0)
   {
   }
 
-  io_service_type& get_io_service()
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
   {
-    return io_service_;
+    return io_context_.get_executor();
   }
 
   void reset(const void* data, size_t length)
@@ -72,22 +73,20 @@ class test_stream
     next_read_length_ = length;
   }
 
-  template <typename Const_Buffers>
-  bool check_buffers(const Const_Buffers& buffers, size_t length)
+  template <typename Iterator>
+  bool check_buffers(Iterator begin, Iterator end, size_t length)
   {
     if (length != position_)
       return false;
 
-    typename Const_Buffers::const_iterator iter = buffers.begin();
-    typename Const_Buffers::const_iterator end = buffers.end();
+    Iterator iter = begin;
     size_t checked_length = 0;
     for (; iter != end && checked_length < length; ++iter)
     {
       size_t buffer_length = boost::asio::buffer_size(*iter);
       if (buffer_length > length - checked_length)
         buffer_length = length - checked_length;
-      if (memcmp(data_ + checked_length,
-            boost::asio::buffer_cast<const void*>(*iter), buffer_length) != 0)
+      if (memcmp(data_ + checked_length, iter->data(), buffer_length) != 0)
         return false;
       checked_length += buffer_length;
     }
@@ -95,6 +94,13 @@ class test_stream
     return true;
   }
 
+  template <typename Const_Buffers>
+  bool check_buffers(const Const_Buffers& buffers, size_t length)
+  {
+    return check_buffers(boost::asio::buffer_sequence_begin(buffers),
+        boost::asio::buffer_sequence_end(buffers), length);
+  }
+
   template <typename Mutable_Buffers>
   size_t read_some(const Mutable_Buffers& buffers)
   {
@@ -117,12 +123,14 @@ class test_stream
   void async_read_some(const Mutable_Buffers& buffers, Handler handler)
   {
     size_t bytes_transferred = read_some(buffers);
-    io_service_.post(boost::asio::detail::bind_handler(
-          handler, boost::system::error_code(), bytes_transferred));
+    boost::asio::post(get_executor(),
+        boost::asio::detail::bind_handler(
+          BOOST_ASIO_MOVE_CAST(Handler)(handler),
+          boost::system::error_code(), bytes_transferred));
   }
 
 private:
-  io_service_type& io_service_;
+  boost::asio::io_context& io_context_;
   enum { max_length = 8192 };
   char data_[max_length];
   size_t length_;
@@ -135,20 +143,20 @@ static const char read_data[]
 
 void test_2_arg_zero_buffers_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::mutable_buffer> buffers;
 
   size_t bytes_transferred = boost::asio::read(s, buffers);
   BOOST_ASIO_CHECK(bytes_transferred == 0);
 }
 
-void test_2_arg_mutable_buffers_1_read()
+void test_2_arg_mutable_buffer_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -174,12 +182,13 @@ void test_2_arg_mutable_buffers_1_read()
 
 void test_2_arg_vector_buffers_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
-  buffers.push_back(boost::asio::buffer(read_buf) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf, 39) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf) + 39);
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -204,8 +213,8 @@ void test_2_arg_vector_buffers_read()
 
 void test_2_arg_streambuf_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -234,8 +243,8 @@ void test_2_arg_streambuf_read()
 
 void test_3_arg_nothrow_zero_buffers_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::mutable_buffer> buffers;
 
   boost::system::error_code error;
@@ -244,12 +253,12 @@ void test_3_arg_nothrow_zero_buffers_read()
   BOOST_ASIO_CHECK(!error);
 }
 
-void test_3_arg_nothrow_mutable_buffers_1_read()
+void test_3_arg_nothrow_mutable_buffer_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -279,12 +288,13 @@ void test_3_arg_nothrow_mutable_buffers_1_read()
 
 void test_3_arg_nothrow_vector_buffers_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
-  buffers.push_back(boost::asio::buffer(read_buf) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf, 39) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf) + 39);
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -313,8 +323,8 @@ void test_3_arg_nothrow_vector_buffers_read()
 
 void test_3_arg_nothrow_streambuf_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -357,12 +367,12 @@ size_t short_transfer(const boost::system::error_code& ec,
   return !!ec ? 0 : 3;
 }
 
-void test_3_arg_mutable_buffers_1_read()
+void test_3_arg_mutable_buffer_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -569,12 +579,13 @@ void test_3_arg_mutable_buffers_1_read()
 
 void test_3_arg_vector_buffers_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
-  buffers.push_back(boost::asio::buffer(read_buf) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf, 39) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf) + 39);
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -780,8 +791,8 @@ void test_3_arg_vector_buffers_read()
 
 void test_3_arg_streambuf_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -1013,12 +1024,12 @@ void test_3_arg_streambuf_read()
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
 }
 
-void test_4_arg_mutable_buffers_1_read()
+void test_4_arg_mutable_buffer_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -1280,12 +1291,13 @@ void test_4_arg_mutable_buffers_1_read()
 
 void test_4_arg_vector_buffers_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
-  buffers.push_back(boost::asio::buffer(read_buf) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf, 39) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf) + 39);
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -1546,8 +1558,8 @@ void test_4_arg_vector_buffers_read()
 
 void test_4_arg_streambuf_read()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -1842,7 +1854,7 @@ void async_read_handler(const boost::system::error_code& e,
   BOOST_ASIO_CHECK(bytes_transferred == expected_bytes_transferred);
 }
 
-void test_3_arg_mutable_buffers_1_async_read()
+void test_3_arg_mutable_buffer_async_read()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -1852,10 +1864,10 @@ void test_3_arg_mutable_buffers_1_async_read()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -1864,8 +1876,8 @@ void test_3_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -1876,8 +1888,8 @@ void test_3_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -1888,8 +1900,8 @@ void test_3_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -1897,8 +1909,8 @@ void test_3_arg_mutable_buffers_1_async_read()
   memset(read_buf, 0, sizeof(read_buf));
   int i = boost::asio::async_read(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 }
 
@@ -1913,8 +1925,8 @@ void test_3_arg_boost_array_buffers_async_read()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   boost::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -1926,8 +1938,8 @@ void test_3_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -1938,8 +1950,8 @@ void test_3_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -1950,8 +1962,8 @@ void test_3_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -1959,8 +1971,8 @@ void test_3_arg_boost_array_buffers_async_read()
   memset(read_buf, 0, sizeof(read_buf));
   int i = boost::asio::async_read(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -1976,8 +1988,8 @@ void test_3_arg_std_array_buffers_async_read()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -1989,8 +2001,8 @@ void test_3_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2001,8 +2013,8 @@ void test_3_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2013,8 +2025,8 @@ void test_3_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2022,8 +2034,8 @@ void test_3_arg_std_array_buffers_async_read()
   memset(read_buf, 0, sizeof(read_buf));
   int i = boost::asio::async_read(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -2038,12 +2050,13 @@ void test_3_arg_vector_buffers_async_read()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
-  buffers.push_back(boost::asio::buffer(read_buf) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf, 39) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf) + 39);
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -2051,8 +2064,8 @@ void test_3_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2063,8 +2076,8 @@ void test_3_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2075,8 +2088,8 @@ void test_3_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2084,8 +2097,8 @@ void test_3_arg_vector_buffers_async_read()
   memset(read_buf, 0, sizeof(read_buf));
   int i = boost::asio::async_read(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 }
 
@@ -2099,8 +2112,8 @@ void test_3_arg_streambuf_async_read()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -2109,8 +2122,8 @@ void test_3_arg_streambuf_async_read()
   boost::asio::async_read(s, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -2122,8 +2135,8 @@ void test_3_arg_streambuf_async_read()
   boost::asio::async_read(s, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -2135,8 +2148,8 @@ void test_3_arg_streambuf_async_read()
   boost::asio::async_read(s, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -2145,13 +2158,13 @@ void test_3_arg_streambuf_async_read()
   sb.consume(sb.size());
   int i = boost::asio::async_read(s, sb, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
 }
 
-void test_4_arg_mutable_buffers_1_async_read()
+void test_4_arg_mutable_buffer_async_read()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -2161,10 +2174,10 @@ void test_4_arg_mutable_buffers_1_async_read()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -2173,8 +2186,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2185,8 +2198,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2197,8 +2210,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2208,8 +2221,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2220,8 +2233,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2232,8 +2245,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2243,8 +2256,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2255,8 +2268,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2267,8 +2280,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2278,8 +2291,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2290,8 +2303,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2302,8 +2315,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -2313,8 +2326,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2325,8 +2338,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2337,8 +2350,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2348,8 +2361,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2360,8 +2373,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2372,8 +2385,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2383,8 +2396,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2395,8 +2408,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2407,8 +2420,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2418,8 +2431,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2430,8 +2443,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2442,8 +2455,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2453,8 +2466,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2465,8 +2478,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2477,8 +2490,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2487,8 +2500,8 @@ void test_4_arg_mutable_buffers_1_async_read()
   int i = boost::asio::async_read(s, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 }
 
@@ -2503,8 +2516,8 @@ void test_4_arg_boost_array_buffers_async_read()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   boost::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -2516,8 +2529,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2528,8 +2541,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2540,8 +2553,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2551,8 +2564,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2563,8 +2576,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2575,8 +2588,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2586,8 +2599,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2598,8 +2611,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2610,8 +2623,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2621,8 +2634,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2633,8 +2646,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2645,8 +2658,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -2656,8 +2669,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2668,8 +2681,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2680,8 +2693,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2691,8 +2704,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2703,8 +2716,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2715,8 +2728,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2726,8 +2739,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2738,8 +2751,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2750,8 +2763,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2761,8 +2774,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2773,8 +2786,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2785,8 +2798,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2796,8 +2809,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2808,8 +2821,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2820,8 +2833,8 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2830,8 +2843,8 @@ void test_4_arg_boost_array_buffers_async_read()
   int i = boost::asio::async_read(s, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -2847,8 +2860,8 @@ void test_4_arg_std_array_buffers_async_read()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -2860,8 +2873,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2872,8 +2885,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2884,8 +2897,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2895,8 +2908,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2907,8 +2920,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2919,8 +2932,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2930,8 +2943,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2942,8 +2955,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2954,8 +2967,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2965,8 +2978,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -2977,8 +2990,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2989,8 +3002,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -3000,8 +3013,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3012,8 +3025,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3024,8 +3037,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3035,8 +3048,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3047,8 +3060,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3059,8 +3072,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3070,8 +3083,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3082,8 +3095,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3094,8 +3107,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3105,8 +3118,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3117,8 +3130,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3129,8 +3142,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3140,8 +3153,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3152,8 +3165,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3164,8 +3177,8 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3174,8 +3187,8 @@ void test_4_arg_std_array_buffers_async_read()
   int i = boost::asio::async_read(s, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -3190,12 +3203,13 @@ void test_4_arg_vector_buffers_async_read()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
-  buffers.push_back(boost::asio::buffer(read_buf) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf, 39) + 32);
+  buffers.push_back(boost::asio::buffer(read_buf) + 39);
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -3203,8 +3217,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3215,8 +3229,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3227,8 +3241,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3238,8 +3252,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3250,8 +3264,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3262,8 +3276,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3273,8 +3287,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3285,8 +3299,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3297,8 +3311,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3308,8 +3322,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3320,8 +3334,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3332,8 +3346,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -3343,8 +3357,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3355,8 +3369,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3367,8 +3381,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3378,8 +3392,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3390,8 +3404,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3402,8 +3416,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3413,8 +3427,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3425,8 +3439,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3437,8 +3451,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3448,8 +3462,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3460,8 +3474,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3472,8 +3486,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3483,8 +3497,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3495,8 +3509,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3507,8 +3521,8 @@ void test_4_arg_vector_buffers_async_read()
   boost::asio::async_read(s, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 
@@ -3517,8 +3531,8 @@ void test_4_arg_vector_buffers_async_read()
   int i = boost::asio::async_read(s, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(read_data)));
 }
 
@@ -3532,8 +3546,8 @@ void test_4_arg_streambuf_async_read()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -3542,8 +3556,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3555,8 +3569,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3568,8 +3582,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3580,8 +3594,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3593,8 +3607,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 1));
@@ -3606,8 +3620,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 10));
@@ -3618,8 +3632,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3631,8 +3645,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 10));
@@ -3644,8 +3658,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 10));
@@ -3656,8 +3670,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3669,8 +3683,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 42));
@@ -3682,8 +3696,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 50);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 50));
@@ -3694,8 +3708,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 1));
@@ -3707,8 +3721,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 1));
@@ -3720,8 +3734,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 1));
@@ -3732,8 +3746,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 10));
@@ -3745,8 +3759,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 10));
@@ -3758,8 +3772,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 10));
@@ -3770,8 +3784,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 42));
@@ -3783,8 +3797,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 42));
@@ -3796,8 +3810,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), 42));
@@ -3808,8 +3822,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3821,8 +3835,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3834,8 +3848,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3846,8 +3860,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3859,8 +3873,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3872,8 +3886,8 @@ void test_4_arg_streambuf_async_read()
   boost::asio::async_read(s, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
@@ -3883,8 +3897,8 @@ void test_4_arg_streambuf_async_read()
   int i = boost::asio::async_read(s, sb,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(sb.data(), sizeof(read_data)));
 }
@@ -3893,25 +3907,25 @@ BOOST_ASIO_TEST_SUITE
 (
   "read",
   BOOST_ASIO_TEST_CASE(test_2_arg_zero_buffers_read)
-  BOOST_ASIO_TEST_CASE(test_2_arg_mutable_buffers_1_read)
+  BOOST_ASIO_TEST_CASE(test_2_arg_mutable_buffer_read)
   BOOST_ASIO_TEST_CASE(test_2_arg_vector_buffers_read)
   BOOST_ASIO_TEST_CASE(test_2_arg_streambuf_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_zero_buffers_read)
-  BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_mutable_buffers_1_read)
+  BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_mutable_buffer_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_vector_buffers_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_streambuf_read)
-  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffers_1_read)
+  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffer_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_vector_buffers_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_streambuf_read)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_read)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_read)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_read)
   BOOST_ASIO_TEST_CASE(test_4_arg_streambuf_read)
-  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffers_1_async_read)
+  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffer_async_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_boost_array_buffers_async_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_std_array_buffers_async_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_vector_buffers_async_read)
   BOOST_ASIO_TEST_CASE(test_3_arg_streambuf_async_read)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_async_read)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_async_read)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_async_read)
   BOOST_ASIO_TEST_CASE(test_4_arg_boost_array_buffers_async_read)
   BOOST_ASIO_TEST_CASE(test_4_arg_std_array_buffers_async_read)
diff --git a/test/read_at.cpp b/test/read_at.cpp
index 1f9fc2d570..6d9a9e1d4f 100644
--- a/test/read_at.cpp
+++ b/test/read_at.cpp
@@ -18,7 +18,8 @@
 
 #include <cstring>
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/streambuf.hpp>
 #include "unit_test.hpp"
 
@@ -41,18 +42,18 @@ using namespace std; // For memcmp, memcpy and memset.
 class test_random_access_device
 {
 public:
-  typedef boost::asio::io_service io_service_type;
+  typedef boost::asio::io_context::executor_type executor_type;
 
-  test_random_access_device(boost::asio::io_service& io_service)
-    : io_service_(io_service),
+  test_random_access_device(boost::asio::io_context& io_context)
+    : io_context_(io_context),
       length_(0),
       next_read_length_(0)
   {
   }
 
-  io_service_type& get_io_service()
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
   {
-    return io_service_;
+    return io_context_.get_executor();
   }
 
   void reset(const void* data, size_t length)
@@ -74,15 +75,14 @@ class test_random_access_device
     next_read_length_ = length;
   }
 
-  template <typename Const_Buffers>
+  template <typename Iterator>
   bool check_buffers(boost::asio::uint64_t offset,
-      const Const_Buffers& buffers, size_t length)
+      Iterator begin, Iterator end, size_t length)
   {
     if (offset + length > max_length)
       return false;
 
-    typename Const_Buffers::const_iterator iter = buffers.begin();
-    typename Const_Buffers::const_iterator end = buffers.end();
+    Iterator iter = begin;
     size_t checked_length = 0;
     for (; iter != end && checked_length < length; ++iter)
     {
@@ -90,7 +90,7 @@ class test_random_access_device
       if (buffer_length > length - checked_length)
         buffer_length = length - checked_length;
       if (memcmp(data_ + offset + checked_length,
-            boost::asio::buffer_cast<const void*>(*iter), buffer_length) != 0)
+            iter->data(), buffer_length) != 0)
         return false;
       checked_length += buffer_length;
     }
@@ -98,6 +98,14 @@ class test_random_access_device
     return true;
   }
 
+  template <typename Const_Buffers>
+  bool check_buffers(boost::asio::uint64_t offset,
+      const Const_Buffers& buffers, size_t length)
+  {
+    return check_buffers(offset, boost::asio::buffer_sequence_begin(buffers),
+        boost::asio::buffer_sequence_end(buffers), length);
+  }
+
   template <typename Mutable_Buffers>
   size_t read_some_at(boost::asio::uint64_t offset,
       const Mutable_Buffers& buffers)
@@ -120,12 +128,14 @@ class test_random_access_device
       const Mutable_Buffers& buffers, Handler handler)
   {
     size_t bytes_transferred = read_some_at(offset, buffers);
-    io_service_.post(boost::asio::detail::bind_handler(
-          handler, boost::system::error_code(), bytes_transferred));
+    boost::asio::post(get_executor(),
+        boost::asio::detail::bind_handler(
+          BOOST_ASIO_MOVE_CAST(Handler)(handler),
+          boost::system::error_code(), bytes_transferred));
   }
 
 private:
-  io_service_type& io_service_;
+  boost::asio::io_context& io_context_;
   enum { max_length = 8192 };
   char data_[max_length];
   size_t length_;
@@ -135,12 +145,12 @@ class test_random_access_device
 static const char read_data[]
   = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 
-void test_3_arg_mutable_buffers_1_read_at()
+void test_3_arg_mutable_buffer_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -186,8 +196,8 @@ void test_3_arg_mutable_buffers_1_read_at()
 
 void test_3_arg_vector_buffers_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
@@ -236,8 +246,8 @@ void test_3_arg_vector_buffers_read_at()
 
 void test_3_arg_streambuf_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -287,12 +297,12 @@ void test_3_arg_streambuf_read_at()
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
 }
 
-void test_4_arg_nothrow_mutable_buffers_1_read_at()
+void test_4_arg_nothrow_mutable_buffer_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -345,8 +355,8 @@ void test_4_arg_nothrow_mutable_buffers_1_read_at()
 
 void test_4_arg_nothrow_vector_buffers_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
@@ -402,8 +412,8 @@ void test_4_arg_nothrow_vector_buffers_read_at()
 
 void test_4_arg_nothrow_streambuf_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -472,12 +482,12 @@ size_t short_transfer(const boost::system::error_code& ec,
   return !!ec ? 0 : 3;
 }
 
-void test_4_arg_mutable_buffers_1_read_at()
+void test_4_arg_mutable_buffer_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -891,8 +901,8 @@ void test_4_arg_mutable_buffers_1_read_at()
 
 void test_4_arg_vector_buffers_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
@@ -1309,8 +1319,8 @@ void test_4_arg_vector_buffers_read_at()
 
 void test_4_arg_streambuf_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -1776,12 +1786,12 @@ void test_4_arg_streambuf_read_at()
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
 }
 
-void test_5_arg_mutable_buffers_1_read_at()
+void test_5_arg_mutable_buffer_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -2304,8 +2314,8 @@ void test_5_arg_mutable_buffers_1_read_at()
 
 void test_5_arg_vector_buffers_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
@@ -2831,8 +2841,8 @@ void test_5_arg_vector_buffers_read_at()
 
 void test_5_arg_streambuf_read_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -3415,7 +3425,7 @@ void async_read_handler(const boost::system::error_code& e,
   BOOST_ASIO_CHECK(bytes_transferred == expected_bytes_transferred);
 }
 
-void test_4_arg_mutable_buffers_1_async_read_at()
+void test_4_arg_mutable_buffer_async_read_at()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -3425,10 +3435,10 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -3437,8 +3447,8 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3448,8 +3458,8 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3460,8 +3470,8 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3472,8 +3482,8 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3484,8 +3494,8 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3496,8 +3506,8 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3506,8 +3516,8 @@ void test_4_arg_mutable_buffers_1_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 }
 
@@ -3522,8 +3532,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   boost::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -3535,8 +3545,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3546,8 +3556,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3558,8 +3568,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3570,8 +3580,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3582,8 +3592,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3594,8 +3604,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3604,8 +3614,8 @@ void test_4_arg_boost_array_buffers_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -3621,8 +3631,8 @@ void test_4_arg_std_array_buffers_async_read_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -3634,8 +3644,8 @@ void test_4_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3645,8 +3655,8 @@ void test_4_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3657,8 +3667,8 @@ void test_4_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3669,8 +3679,8 @@ void test_4_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3681,8 +3691,8 @@ void test_4_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3693,8 +3703,8 @@ void test_4_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3703,8 +3713,8 @@ void test_4_arg_std_array_buffers_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -3719,8 +3729,8 @@ void test_4_arg_vector_buffers_async_read_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
@@ -3732,8 +3742,8 @@ void test_4_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3743,8 +3753,8 @@ void test_4_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3755,8 +3765,8 @@ void test_4_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3767,8 +3777,8 @@ void test_4_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3779,8 +3789,8 @@ void test_4_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3791,8 +3801,8 @@ void test_4_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3801,8 +3811,8 @@ void test_4_arg_vector_buffers_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 }
 
@@ -3816,8 +3826,8 @@ void test_4_arg_streambuf_async_read_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -3826,8 +3836,8 @@ void test_4_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -3838,8 +3848,8 @@ void test_4_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -3851,8 +3861,8 @@ void test_4_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -3864,8 +3874,8 @@ void test_4_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -3877,8 +3887,8 @@ void test_4_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -3890,8 +3900,8 @@ void test_4_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -3901,12 +3911,12 @@ void test_4_arg_streambuf_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, sb,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
 }
 
-void test_5_arg_mutable_buffers_1_async_read_at()
+void test_5_arg_mutable_buffer_async_read_at()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -3916,10 +3926,10 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(read_buf, sizeof(read_buf));
 
   s.reset(read_data, sizeof(read_data));
@@ -3929,8 +3939,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3941,8 +3951,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3954,8 +3964,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3967,8 +3977,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -3980,8 +3990,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -3993,8 +4003,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4005,8 +4015,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4017,8 +4027,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4030,8 +4040,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4043,8 +4053,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4056,8 +4066,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4069,8 +4079,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4081,8 +4091,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4093,8 +4103,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4106,8 +4116,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4119,8 +4129,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4132,8 +4142,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4145,8 +4155,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4157,8 +4167,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4169,8 +4179,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4182,8 +4192,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4195,8 +4205,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4208,8 +4218,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -4221,8 +4231,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -4233,8 +4243,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4245,8 +4255,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4258,8 +4268,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4271,8 +4281,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4284,8 +4294,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4297,8 +4307,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4309,8 +4319,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4321,8 +4331,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4334,8 +4344,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4347,8 +4357,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4360,8 +4370,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4373,8 +4383,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4385,8 +4395,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4397,8 +4407,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4410,8 +4420,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4423,8 +4433,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4436,8 +4446,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4449,8 +4459,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4460,8 +4470,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4471,8 +4481,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4483,8 +4493,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4495,8 +4505,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4507,8 +4517,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4519,8 +4529,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4530,8 +4540,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4541,8 +4551,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4553,8 +4563,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4565,8 +4575,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4577,8 +4587,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4589,8 +4599,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4599,8 +4609,8 @@ void test_5_arg_mutable_buffers_1_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 }
 
@@ -4615,8 +4625,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   boost::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -4629,8 +4639,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4641,8 +4651,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4654,8 +4664,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4667,8 +4677,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4680,8 +4690,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4693,8 +4703,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4705,8 +4715,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4717,8 +4727,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4730,8 +4740,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4743,8 +4753,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4756,8 +4766,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4769,8 +4779,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4781,8 +4791,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4793,8 +4803,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4806,8 +4816,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4819,8 +4829,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4832,8 +4842,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4845,8 +4855,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4857,8 +4867,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -4869,8 +4879,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -4882,8 +4892,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4895,8 +4905,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4908,8 +4918,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -4921,8 +4931,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -4933,8 +4943,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4945,8 +4955,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4958,8 +4968,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4971,8 +4981,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4984,8 +4994,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4997,8 +5007,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5009,8 +5019,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5021,8 +5031,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5034,8 +5044,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5047,8 +5057,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5060,8 +5070,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5073,8 +5083,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5085,8 +5095,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5097,8 +5107,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5110,8 +5120,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5123,8 +5133,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5136,8 +5146,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5149,8 +5159,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5160,8 +5170,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5171,8 +5181,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5183,8 +5193,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5195,8 +5205,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5207,8 +5217,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5219,8 +5229,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5230,8 +5240,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5241,8 +5251,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5253,8 +5263,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5265,8 +5275,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5277,8 +5287,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5289,8 +5299,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5299,8 +5309,8 @@ void test_5_arg_boost_array_buffers_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -5316,8 +5326,8 @@ void test_5_arg_std_array_buffers_async_read_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::array<boost::asio::mutable_buffer, 2> buffers = { {
     boost::asio::buffer(read_buf, 32),
@@ -5330,8 +5340,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5342,8 +5352,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5355,8 +5365,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5368,8 +5378,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5381,8 +5391,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5394,8 +5404,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5406,8 +5416,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5418,8 +5428,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5431,8 +5441,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5444,8 +5454,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5457,8 +5467,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5470,8 +5480,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5482,8 +5492,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5494,8 +5504,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5507,8 +5517,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5520,8 +5530,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5533,8 +5543,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5546,8 +5556,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5558,8 +5568,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5570,8 +5580,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5583,8 +5593,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5596,8 +5606,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5609,8 +5619,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -5622,8 +5632,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -5634,8 +5644,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5646,8 +5656,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5659,8 +5669,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5672,8 +5682,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5685,8 +5695,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5698,8 +5708,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5710,8 +5720,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5722,8 +5732,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5735,8 +5745,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5748,8 +5758,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5761,8 +5771,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5774,8 +5784,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5786,8 +5796,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5798,8 +5808,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5811,8 +5821,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5824,8 +5834,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5837,8 +5847,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5850,8 +5860,8 @@ void test_5_arg_std_array_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5861,8 +5871,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5872,8 +5882,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5884,8 +5894,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5896,8 +5906,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5908,8 +5918,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5920,8 +5930,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5931,8 +5941,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5942,8 +5952,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5954,8 +5964,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5966,8 +5976,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -5978,8 +5988,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -5990,8 +6000,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6000,8 +6010,8 @@ void test_5_arg_std_array_buffers_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -6016,8 +6026,8 @@ void test_5_arg_vector_buffers_async_read_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
   std::vector<boost::asio::mutable_buffer> buffers;
   buffers.push_back(boost::asio::buffer(read_buf, 32));
@@ -6030,8 +6040,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6042,8 +6052,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6055,8 +6065,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6068,8 +6078,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6081,8 +6091,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6094,8 +6104,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6106,8 +6116,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6118,8 +6128,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6131,8 +6141,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6144,8 +6154,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6157,8 +6167,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6170,8 +6180,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6182,8 +6192,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6194,8 +6204,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6207,8 +6217,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6220,8 +6230,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6233,8 +6243,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6246,8 +6256,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6258,8 +6268,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6270,8 +6280,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6283,8 +6293,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6296,8 +6306,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6309,8 +6319,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -6322,8 +6332,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -6334,8 +6344,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6346,8 +6356,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6359,8 +6369,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6372,8 +6382,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6385,8 +6395,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6398,8 +6408,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6410,8 +6420,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6422,8 +6432,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6435,8 +6445,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6448,8 +6458,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6461,8 +6471,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6474,8 +6484,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6486,8 +6496,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6498,8 +6508,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6511,8 +6521,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6524,8 +6534,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6537,8 +6547,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6550,8 +6560,8 @@ void test_5_arg_vector_buffers_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6561,8 +6571,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6572,8 +6582,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6584,8 +6594,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6596,8 +6606,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6608,8 +6618,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6620,8 +6630,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6631,8 +6641,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6642,8 +6652,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6654,8 +6664,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6666,8 +6676,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6678,8 +6688,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 0, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(read_data)));
 
@@ -6690,8 +6700,8 @@ void test_5_arg_vector_buffers_async_read_at()
   boost::asio::async_read_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 
@@ -6700,8 +6710,8 @@ void test_5_arg_vector_buffers_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, buffers,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(read_data)));
 }
 
@@ -6715,8 +6725,8 @@ void test_5_arg_streambuf_async_read_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb(sizeof(read_data));
 
   s.reset(read_data, sizeof(read_data));
@@ -6726,8 +6736,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -6739,8 +6749,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -6753,8 +6763,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -6767,8 +6777,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -6781,8 +6791,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -6795,8 +6805,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_all(),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -6808,8 +6818,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -6821,8 +6831,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -6835,8 +6845,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 1));
@@ -6849,8 +6859,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 1));
@@ -6863,8 +6873,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 10));
@@ -6877,8 +6887,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 10));
@@ -6890,8 +6900,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -6903,8 +6913,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -6917,8 +6927,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 10));
@@ -6931,8 +6941,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 10));
@@ -6945,8 +6955,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 10));
@@ -6959,8 +6969,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 10));
@@ -6972,8 +6982,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -6985,8 +6995,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -6999,8 +7009,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 42));
@@ -7013,8 +7023,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 42));
@@ -7027,8 +7037,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 50);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 50));
@@ -7041,8 +7051,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_read_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 50);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 50));
@@ -7054,8 +7064,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 1));
@@ -7067,8 +7077,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 1));
@@ -7081,8 +7091,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 1));
@@ -7095,8 +7105,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 1));
@@ -7109,8 +7119,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 1));
@@ -7123,8 +7133,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_read_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 1);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 1));
@@ -7136,8 +7146,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 10));
@@ -7149,8 +7159,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 10));
@@ -7163,8 +7173,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 10));
@@ -7177,8 +7187,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 10));
@@ -7191,8 +7201,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 10));
@@ -7205,8 +7215,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_read_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 10);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 10));
@@ -7218,8 +7228,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 42));
@@ -7231,8 +7241,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 42));
@@ -7245,8 +7255,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 42));
@@ -7259,8 +7269,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 42));
@@ -7273,8 +7283,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), 42));
@@ -7287,8 +7297,8 @@ void test_5_arg_streambuf_async_read_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_read_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == 42);
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), 42));
@@ -7299,8 +7309,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -7311,8 +7321,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -7324,8 +7334,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -7337,8 +7347,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -7350,8 +7360,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -7363,8 +7373,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb, old_style_transfer_all,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -7375,8 +7385,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -7387,8 +7397,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -7400,8 +7410,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -7413,8 +7423,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -7426,8 +7436,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 0, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(0, sb.data(), sizeof(read_data)));
@@ -7439,8 +7449,8 @@ void test_5_arg_streambuf_async_read_at()
   boost::asio::async_read_at(s, 1234, sb, short_transfer,
       bindns::bind(async_read_handler,
         _1, _2, sizeof(read_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(sb.size() == sizeof(read_data));
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
@@ -7450,32 +7460,32 @@ void test_5_arg_streambuf_async_read_at()
   int i = boost::asio::async_read_at(s, 1234, sb,
       short_transfer, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(1234, sb.data(), sizeof(read_data)));
 }
 
 BOOST_ASIO_TEST_SUITE
 (
   "read_at",
-  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffers_1_read_at)
+  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffer_read_at)
   BOOST_ASIO_TEST_CASE(test_3_arg_vector_buffers_read_at)
   BOOST_ASIO_TEST_CASE(test_3_arg_streambuf_read_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_mutable_buffers_1_read_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_mutable_buffer_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_vector_buffers_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_streambuf_read_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_read_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_streambuf_read_at)
-  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffers_1_read_at)
+  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffer_read_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_vector_buffers_read_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_streambuf_read_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_async_read_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_async_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_boost_array_buffers_async_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_std_array_buffers_async_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_async_read_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_streambuf_async_read_at)
-  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffers_1_async_read_at)
+  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffer_async_read_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_boost_array_buffers_async_read_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_std_array_buffers_async_read_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_vector_buffers_async_read_at)
diff --git a/test/read_until.cpp b/test/read_until.cpp
index be52ce381a..eb0e25c028 100644
--- a/test/read_until.cpp
+++ b/test/read_until.cpp
@@ -18,7 +18,8 @@
 
 #include <cstring>
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/streambuf.hpp>
 #include "unit_test.hpp"
 
@@ -31,19 +32,19 @@
 class test_stream
 {
 public:
-  typedef boost::asio::io_service io_service_type;
+  typedef boost::asio::io_context::executor_type executor_type;
 
-  test_stream(boost::asio::io_service& io_service)
-    : io_service_(io_service),
+  test_stream(boost::asio::io_context& io_context)
+    : io_context_(io_context),
       length_(0),
       position_(0),
       next_read_length_(0)
   {
   }
 
-  io_service_type& get_io_service()
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
   {
-    return io_service_;
+    return io_context_.get_executor();
   }
 
   void reset(const void* data, size_t length)
@@ -85,12 +86,14 @@ class test_stream
   void async_read_some(const Mutable_Buffers& buffers, Handler handler)
   {
     size_t bytes_transferred = read_some(buffers);
-    io_service_.post(boost::asio::detail::bind_handler(
-          handler, boost::system::error_code(), bytes_transferred));
+    boost::asio::post(get_executor(),
+        boost::asio::detail::bind_handler(
+          BOOST_ASIO_MOVE_CAST(Handler)(handler),
+          boost::system::error_code(), bytes_transferred));
   }
 
 private:
-  io_service_type& io_service_;
+  boost::asio::io_context& io_context_;
   enum { max_length = 8192 };
   char data_[max_length];
   size_t length_;
@@ -103,8 +106,8 @@ static const char read_data[]
 
 void test_char_read_until()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb1;
   boost::asio::streambuf sb2(25);
   boost::system::error_code ec;
@@ -189,8 +192,8 @@ void test_char_read_until()
 
 void test_string_read_until()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb1;
   boost::asio::streambuf sb2(25);
   boost::system::error_code ec;
@@ -304,8 +307,8 @@ namespace asio {
 
 void test_match_condition_read_until()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb1;
   boost::asio::streambuf sb2(25);
   boost::system::error_code ec;
@@ -407,8 +410,8 @@ void test_char_async_read_until()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb1;
   boost::asio::streambuf sb2(25);
   boost::system::error_code ec;
@@ -423,8 +426,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb1, 'Z',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -438,8 +441,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb1, 'Z',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -453,8 +456,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb1, 'Z',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -467,8 +470,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb2, 'Z',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -482,8 +485,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb2, 'Z',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -497,8 +500,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb2, 'Z',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -511,8 +514,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb2, 'Y',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -526,8 +529,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb2, 'Y',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -541,8 +544,8 @@ void test_char_async_read_until()
   boost::asio::async_read_until(s, sb2, 'Y',
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -552,8 +555,8 @@ void test_char_async_read_until()
   int i = boost::asio::async_read_until(s, sb2, 'Y',
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 }
 
 void test_string_async_read_until()
@@ -566,8 +569,8 @@ void test_string_async_read_until()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb1;
   boost::asio::streambuf sb2(25);
   boost::system::error_code ec;
@@ -582,8 +585,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb1, "XYZ",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -597,8 +600,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb1, "XYZ",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -612,8 +615,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb1, "XYZ",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -626,8 +629,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb2, "XYZ",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -641,8 +644,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb2, "XYZ",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -656,8 +659,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb2, "XYZ",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -670,8 +673,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb2, "WXY",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -685,8 +688,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb2, "WXY",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -700,8 +703,8 @@ void test_string_async_read_until()
   boost::asio::async_read_until(s, sb2, "WXY",
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -711,8 +714,8 @@ void test_string_async_read_until()
   int i = boost::asio::async_read_until(s, sb2, "WXY",
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 }
 
 void test_match_condition_async_read_until()
@@ -725,8 +728,8 @@ void test_match_condition_async_read_until()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb1;
   boost::asio::streambuf sb2(25);
   boost::system::error_code ec;
@@ -741,8 +744,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb1, match_char('Z'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -756,8 +759,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb1, match_char('Z'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -771,8 +774,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb1, match_char('Z'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 26);
@@ -785,8 +788,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb2, match_char('Z'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -800,8 +803,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb2, match_char('Z'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -815,8 +818,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb2, match_char('Z'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(ec == boost::asio::error::not_found);
   BOOST_ASIO_CHECK(length == 0);
@@ -829,8 +832,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb2, match_char('Y'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -844,8 +847,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb2, match_char('Y'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -859,8 +862,8 @@ void test_match_condition_async_read_until()
   boost::asio::async_read_until(s, sb2, match_char('Y'),
       bindns::bind(async_read_handler, _1, &ec,
         _2, &length, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(!ec);
   BOOST_ASIO_CHECK(length == 25);
@@ -870,8 +873,8 @@ void test_match_condition_async_read_until()
   int i = boost::asio::async_read_until(s, sb2, match_char('Y'),
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 }
 
 BOOST_ASIO_TEST_SUITE
diff --git a/test/serial_port.cpp b/test/serial_port.cpp
index d8048d84be..a2ba204d35 100644
--- a/test/serial_port.cpp
+++ b/test/serial_port.cpp
@@ -18,7 +18,7 @@
 #include <boost/asio/serial_port.hpp>
 
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "unit_test.hpp"
 
 //------------------------------------------------------------------------------
@@ -30,13 +30,27 @@
 
 namespace serial_port_compile {
 
-void write_some_handler(const boost::system::error_code&, std::size_t)
+struct write_some_handler
 {
-}
+  write_some_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  write_some_handler(write_some_handler&&) {}
+private:
+  write_some_handler(const write_some_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
-void read_some_handler(const boost::system::error_code&, std::size_t)
+struct read_some_handler
 {
-}
+  read_some_handler() {}
+  void operator()(const boost::system::error_code&, std::size_t) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  read_some_handler(read_some_handler&&) {}
+private:
+  read_some_handler(const read_some_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void test()
 {
@@ -45,7 +59,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     serial_port::baud_rate serial_port_option;
@@ -54,10 +68,10 @@ void test()
 
     // basic_serial_port constructors.
 
-    serial_port port1(ios);
-    serial_port port2(ios, "null");
+    serial_port port1(ioc);
+    serial_port port2(ioc, "null");
     serial_port::native_handle_type native_port1 = port1.native_handle();
-    serial_port port3(ios, native_port1);
+    serial_port port3(ioc, native_port1);
 
 #if defined(BOOST_ASIO_HAS_MOVE)
     serial_port port4(std::move(port3));
@@ -66,14 +80,22 @@ void test()
     // basic_serial_port operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    port1 = serial_port(ios);
+    port1 = serial_port(ioc);
     port1 = std::move(port2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = port1.get_io_service();
-    (void)ios_ref;
+    serial_port::executor_type ex = port1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = port1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = port1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // basic_serial_port functions.
 
@@ -98,12 +120,9 @@ void test()
     port1.close();
     port1.close(ec);
 
-    serial_port::native_type native_port4 = port1.native();
+    serial_port::native_handle_type native_port4 = port1.native_handle();
     (void)native_port4;
 
-    serial_port::native_handle_type native_port5 = port1.native_handle();
-    (void)native_port5;
-
     port1.cancel();
     port1.cancel(ec);
 
@@ -121,8 +140,8 @@ void test()
     port1.write_some(buffer(mutable_char_buffer), ec);
     port1.write_some(buffer(const_char_buffer), ec);
 
-    port1.async_write_some(buffer(mutable_char_buffer), &write_some_handler);
-    port1.async_write_some(buffer(const_char_buffer), &write_some_handler);
+    port1.async_write_some(buffer(mutable_char_buffer), write_some_handler());
+    port1.async_write_some(buffer(const_char_buffer), write_some_handler());
     int i1 = port1.async_write_some(buffer(mutable_char_buffer), lazy);
     (void)i1;
     int i2 = port1.async_write_some(buffer(const_char_buffer), lazy);
@@ -131,7 +150,7 @@ void test()
     port1.read_some(buffer(mutable_char_buffer));
     port1.read_some(buffer(mutable_char_buffer), ec);
 
-    port1.async_read_some(buffer(mutable_char_buffer), &read_some_handler);
+    port1.async_read_some(buffer(mutable_char_buffer), read_some_handler());
     int i3 = port1.async_read_some(buffer(mutable_char_buffer), lazy);
     (void)i3;
   }
diff --git a/test/serial_port_base.cpp b/test/serial_port_base.cpp
index b619f22c79..7f53b7d81d 100644
--- a/test/serial_port_base.cpp
+++ b/test/serial_port_base.cpp
@@ -17,7 +17,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/serial_port_base.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/serial_port.hpp>
 #include "unit_test.hpp"
 
@@ -37,8 +37,8 @@ void test()
 
   try
   {
-    io_service ios;
-    serial_port port(ios);
+    io_context ioc;
+    serial_port port(ioc);
 
     // baud_rate class.
 
diff --git a/test/signal_set.cpp b/test/signal_set.cpp
index 7d1dfddd66..f04f194d5c 100644
--- a/test/signal_set.cpp
+++ b/test/signal_set.cpp
@@ -17,7 +17,7 @@
 #include <boost/asio/signal_set.hpp>
 
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "unit_test.hpp"
 
 //------------------------------------------------------------------------------
@@ -39,21 +39,29 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     archetypes::lazy_handler lazy;
     boost::system::error_code ec;
 
     // basic_signal_set constructors.
 
-    signal_set set1(ios);
-    signal_set set2(ios, 1);
-    signal_set set3(ios, 1, 2);
-    signal_set set4(ios, 1, 2, 3);
+    signal_set set1(ioc);
+    signal_set set2(ioc, 1);
+    signal_set set3(ioc, 1, 2);
+    signal_set set4(ioc, 1, 2, 3);
 
     // basic_io_object functions.
 
-    io_service& ios_ref = set1.get_io_service();
-    (void)ios_ref;
+    signal_set::executor_type ex = set1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = set1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = set1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // basic_signal_set functions.
 
diff --git a/test/socket_base.cpp b/test/socket_base.cpp
index ee4824fee0..37fbe5fb73 100644
--- a/test/socket_base.cpp
+++ b/test/socket_base.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/socket_base.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/ip/tcp.hpp>
 #include <boost/asio/ip/udp.hpp>
 #include "unit_test.hpp"
@@ -37,8 +37,8 @@ void test()
 
   try
   {
-    io_service ios;
-    ip::tcp::socket sock(ios);
+    io_context ioc;
+    ip::tcp::socket sock(ioc);
     char buf[1024];
 
     // shutdown_type enumeration.
@@ -155,6 +155,17 @@ void test()
     linger1.timeout(1);
     (void)static_cast<int>(linger1.timeout());
 
+    // out_of_band_inline class.
+
+    socket_base::out_of_band_inline out_of_band_inline1(true);
+    sock.set_option(out_of_band_inline1);
+    socket_base::out_of_band_inline out_of_band_inline2;
+    sock.get_option(out_of_band_inline2);
+    out_of_band_inline1 = true;
+    (void)static_cast<bool>(out_of_band_inline1);
+    (void)static_cast<bool>(!out_of_band_inline1);
+    (void)static_cast<bool>(out_of_band_inline1.value());
+
     // enable_connection_aborted class.
 
     socket_base::enable_connection_aborted enable_connection_aborted1(true);
@@ -166,11 +177,6 @@ void test()
     (void)static_cast<bool>(!enable_connection_aborted1);
     (void)static_cast<bool>(enable_connection_aborted1.value());
 
-    // non_blocking_io class.
-
-    socket_base::non_blocking_io non_blocking_io(true);
-    sock.io_control(non_blocking_io);
-
     // bytes_readable class.
 
     socket_base::bytes_readable bytes_readable;
@@ -199,10 +205,10 @@ void test()
   using namespace boost::asio;
   namespace ip = boost::asio::ip;
 
-  io_service ios;
-  ip::udp::socket udp_sock(ios, ip::udp::v4());
-  ip::tcp::socket tcp_sock(ios, ip::tcp::v4());
-  ip::tcp::acceptor tcp_acceptor(ios, ip::tcp::v4());
+  io_context ioc;
+  ip::udp::socket udp_sock(ioc, ip::udp::v4());
+  ip::tcp::socket tcp_sock(ioc, ip::tcp::v4());
+  ip::tcp::acceptor tcp_acceptor(ioc, ip::tcp::v4());
   boost::system::error_code ec;
 
   // broadcast class.
@@ -625,16 +631,6 @@ void test()
   BOOST_ASIO_CHECK(!static_cast<bool>(enable_connection_aborted4));
   BOOST_ASIO_CHECK(!enable_connection_aborted4);
 
-  // non_blocking_io class.
-
-  socket_base::non_blocking_io non_blocking_io1(true);
-  tcp_sock.io_control(non_blocking_io1, ec);
-  BOOST_ASIO_CHECK_MESSAGE(!ec, ec.value() << ", " << ec.message());
-
-  socket_base::non_blocking_io non_blocking_io2(false);
-  tcp_sock.io_control(non_blocking_io2, ec);
-  BOOST_ASIO_CHECK_MESSAGE(!ec, ec.value() << ", " << ec.message());
-
   // bytes_readable class.
 
   socket_base::bytes_readable bytes_readable;
diff --git a/test/ssl/Jamfile b/test/ssl/Jamfile
index bf716c1202..77a4bf8fa7 100644
--- a/test/ssl/Jamfile
+++ b/test/ssl/Jamfile
@@ -35,12 +35,9 @@ template unit_test
     $(SOCKET_LIBS)
   ;
 
-run basic_context.cpp <template>unit_test ;
 run context_base.cpp <template>unit_test ;
-run context_service.cpp <template>unit_test ;
 run context.cpp <template>unit_test ;
 run error.cpp <template>unit_test ;
 run rfc2818_verification.cpp <template>unit_test ;
 run stream_base.cpp <template>unit_test ;
-run stream_service.cpp <template>unit_test ;
 run stream.cpp <template>unit_test ;
diff --git a/test/ssl/Jamfile.v2 b/test/ssl/Jamfile.v2
index 1e54e55546..67dd3aaec4 100644
--- a/test/ssl/Jamfile.v2
+++ b/test/ssl/Jamfile.v2
@@ -54,22 +54,16 @@ project
   ;
 
 test-suite "asio-ssl" :
-  [ compile basic_context.cpp ]
-  [ compile basic_context.cpp : $(USE_SELECT) : basic_context_select ]
   [ compile context_base.cpp ]
   [ compile context_base.cpp : $(USE_SELECT) : context_base_select ]
-  [ compile context_service.cpp ]
-  [ compile context_service.cpp : $(USE_SELECT) : context_service_select ]
   [ compile context.cpp ]
   [ compile context.cpp : $(USE_SELECT) : context_select ]
   [ compile error.cpp ]
-  [ compile error.cpp : $(USE_SELECT) : context_select ]
+  [ compile error.cpp : $(USE_SELECT) : error_select ]
   [ compile rfc2818_verification.cpp ]
   [ compile rfc2818_verification.cpp : $(USE_SELECT) : rfc2818_verification_select ]
   [ compile stream_base.cpp ]
   [ compile stream_base.cpp : $(USE_SELECT) : stream_base_select ]
-  [ compile stream_service.cpp ]
-  [ compile stream_service.cpp : $(USE_SELECT) : stream_service_select ]
   [ compile stream.cpp ]
   [ compile stream.cpp : $(USE_SELECT) : stream_select ]
   ;
diff --git a/test/ssl/stream.cpp b/test/ssl/stream.cpp
index ac9f3bd586..3b7b820644 100644
--- a/test/ssl/stream.cpp
+++ b/test/ssl/stream.cpp
@@ -30,12 +30,10 @@
 
 namespace ssl_stream_compile {
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
 bool verify_callback(bool, boost::asio::ssl::verify_context&)
 {
   return false;
 }
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
 
 void handshake_handler(const boost::system::error_code&)
 {
@@ -64,33 +62,36 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
-    boost::asio::ssl::context context(ios, boost::asio::ssl::context::sslv23);
+    boost::asio::ssl::context context(boost::asio::ssl::context::sslv23);
     archetypes::lazy_handler lazy;
     boost::system::error_code ec;
 
     // ssl::stream constructors.
 
-    ssl::stream<ip::tcp::socket> stream1(ios, context);
-    ip::tcp::socket socket1(ios, ip::tcp::v4());
+    ssl::stream<ip::tcp::socket> stream1(ioc, context);
+    ip::tcp::socket socket1(ioc, ip::tcp::v4());
     ssl::stream<ip::tcp::socket&> stream2(socket1, context);
 
     // basic_io_object functions.
 
-    io_service& ios_ref = stream1.get_io_service();
-    (void)ios_ref;
+    ssl::stream<ip::tcp::socket>::executor_type ex = stream1.get_executor();
+    (void)ex;
+
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = stream1.get_io_context();
+    (void)ioc_ref;
+
+    io_context& ioc_ref2 = stream1.get_io_service();
+    (void)ioc_ref2;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
 
     // ssl::stream functions.
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
     SSL* ssl1 = stream1.native_handle();
     (void)ssl1;
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
-
-    SSL* ssl2 = stream1.impl()->ssl;
-    (void)ssl2;
 
     ssl::stream<ip::tcp::socket>::lowest_layer_type& lowest_layer
       = stream1.lowest_layer();
@@ -101,7 +102,6 @@ void test()
       = stream3.lowest_layer();
     (void)lowest_layer2;
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
     stream1.set_verify_mode(ssl::verify_none);
     stream1.set_verify_mode(ssl::verify_none, ec);
 
@@ -110,14 +110,12 @@ void test()
 
     stream1.set_verify_callback(verify_callback);
     stream1.set_verify_callback(verify_callback, ec);
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
 
     stream1.handshake(ssl::stream_base::client);
     stream1.handshake(ssl::stream_base::server);
     stream1.handshake(ssl::stream_base::client, ec);
     stream1.handshake(ssl::stream_base::server, ec);
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
     stream1.handshake(ssl::stream_base::client, buffer(mutable_char_buffer));
     stream1.handshake(ssl::stream_base::server, buffer(mutable_char_buffer));
     stream1.handshake(ssl::stream_base::client, buffer(const_char_buffer));
@@ -130,7 +128,6 @@ void test()
         buffer(const_char_buffer), ec);
     stream1.handshake(ssl::stream_base::server,
         buffer(const_char_buffer), ec);
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
 
     stream1.async_handshake(ssl::stream_base::client, handshake_handler);
     stream1.async_handshake(ssl::stream_base::server, handshake_handler);
@@ -139,7 +136,6 @@ void test()
     int i2 = stream1.async_handshake(ssl::stream_base::server, lazy);
     (void)i2;
 
-#if !defined(BOOST_ASIO_ENABLE_OLD_SSL)
     stream1.async_handshake(ssl::stream_base::client,
         buffer(mutable_char_buffer), buffered_handshake_handler);
     stream1.async_handshake(ssl::stream_base::server,
@@ -160,7 +156,6 @@ void test()
     int i6 = stream1.async_handshake(ssl::stream_base::server,
         buffer(const_char_buffer), lazy);
     (void)i6;
-#endif // !defined(BOOST_ASIO_ENABLE_OLD_SSL)
 
     stream1.shutdown();
     stream1.shutdown(ec);
@@ -187,16 +182,6 @@ void test()
     stream1.async_read_some(buffer(mutable_char_buffer), read_some_handler);
     int i10 = stream1.async_read_some(buffer(mutable_char_buffer), lazy);
     (void)i10;
-
-#if defined(BOOST_ASIO_ENABLE_OLD_SSL)
-    stream1.peek(buffer(mutable_char_buffer));
-    stream1.peek(buffer(mutable_char_buffer), ec);
-
-    std::size_t in_avail1 = stream1.in_avail();
-    (void)in_avail1;
-    std::size_t in_avail2 = stream1.in_avail(ec);
-    (void)in_avail2;
-#endif // defined(BOOST_ASIO_ENABLE_OLD_SSL)
   }
   catch (std::exception&)
   {
diff --git a/test/strand.cpp b/test/strand.cpp
index a311e9174b..f0b2cfd796 100644
--- a/test/strand.cpp
+++ b/test/strand.cpp
@@ -17,7 +17,9 @@
 #include <boost/asio/strand.hpp>
 
 #include <sstream>
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/dispatch.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/detail/thread.hpp>
 #include "unit_test.hpp"
 
@@ -44,12 +46,9 @@ namespace bindns = std;
 #if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 typedef deadline_timer timer;
 namespace chronons = boost::posix_time;
-#elif defined(BOOST_ASIO_HAS_STD_CHRONO)
+#elif defined(BOOST_ASIO_HAS_CHRONO)
 typedef steady_timer timer;
-namespace chronons = std::chrono;
-#elif defined(BOOST_ASIO_HAS_BOOST_CHRONO)
-typedef steady_timer timer;
-namespace chronons = boost::chrono;
+namespace chronons = boost::asio::chrono;
 #endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
 
 void increment(int* count)
@@ -57,50 +56,50 @@ void increment(int* count)
   ++(*count);
 }
 
-void increment_without_lock(io_service::strand* s, int* count)
+void increment_without_lock(io_context::strand* s, int* count)
 {
   BOOST_ASIO_CHECK(!s->running_in_this_thread());
 
   int original_count = *count;
 
-  s->dispatch(bindns::bind(increment, count));
+  dispatch(*s, bindns::bind(increment, count));
 
   // No other functions are currently executing through the locking dispatcher,
   // so the previous call to dispatch should have successfully nested.
   BOOST_ASIO_CHECK(*count == original_count + 1);
 }
 
-void increment_with_lock(io_service::strand* s, int* count)
+void increment_with_lock(io_context::strand* s, int* count)
 {
   BOOST_ASIO_CHECK(s->running_in_this_thread());
 
   int original_count = *count;
 
-  s->dispatch(bindns::bind(increment, count));
+  dispatch(*s, bindns::bind(increment, count));
 
   // The current function already holds the strand's lock, so the
   // previous call to dispatch should have successfully nested.
   BOOST_ASIO_CHECK(*count == original_count + 1);
 }
 
-void sleep_increment(io_service* ios, int* count)
+void sleep_increment(io_context* ioc, int* count)
 {
-  timer t(*ios, chronons::seconds(2));
+  timer t(*ioc, chronons::seconds(2));
   t.wait();
 
   ++(*count);
 }
 
-void start_sleep_increments(io_service* ios, io_service::strand* s, int* count)
+void start_sleep_increments(io_context* ioc, io_context::strand* s, int* count)
 {
   // Give all threads a chance to start.
-  timer t(*ios, chronons::seconds(2));
+  timer t(*ioc, chronons::seconds(2));
   t.wait();
 
   // Start three increments.
-  s->post(bindns::bind(sleep_increment, ios, count));
-  s->post(bindns::bind(sleep_increment, ios, count));
-  s->post(bindns::bind(sleep_increment, ios, count));
+  post(*s, bindns::bind(sleep_increment, ioc, count));
+  post(*s, bindns::bind(sleep_increment, ioc, count));
+  post(*s, bindns::bind(sleep_increment, ioc, count));
 }
 
 void throw_exception()
@@ -108,53 +107,61 @@ void throw_exception()
   throw 1;
 }
 
-void io_service_run(io_service* ios)
+void io_context_run(io_context* ioc)
 {
-  ios->run();
+  ioc->run();
 }
 
 void strand_test()
 {
-  io_service ios;
-  io_service::strand s(ios);
+  io_context ioc;
+  io_context::strand s(ioc);
   int count = 0;
 
-  ios.post(bindns::bind(increment_without_lock, &s, &count));
+  post(ioc, bindns::bind(increment_without_lock, &s, &count));
 
   // No handlers can be called until run() is called.
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
   BOOST_ASIO_CHECK(count == 1);
 
   count = 0;
-  ios.reset();
-  s.post(bindns::bind(increment_with_lock, &s, &count));
+  ioc.restart();
+  post(s, bindns::bind(increment_with_lock, &s, &count));
 
   // No handlers can be called until run() is called.
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all work has finished.
   BOOST_ASIO_CHECK(count == 1);
 
   count = 0;
-  ios.reset();
-  ios.post(bindns::bind(start_sleep_increments, &ios, &s, &count));
-  boost::asio::detail::thread thread1(bindns::bind(io_service_run, &ios));
-  boost::asio::detail::thread thread2(bindns::bind(io_service_run, &ios));
+  ioc.restart();
+  post(ioc, bindns::bind(start_sleep_increments, &ioc, &s, &count));
+  boost::asio::detail::thread thread1(bindns::bind(io_context_run, &ioc));
+  boost::asio::detail::thread thread2(bindns::bind(io_context_run, &ioc));
 
   // Check all events run one after another even though there are two threads.
-  timer timer1(ios, chronons::seconds(3));
+  timer timer1(ioc, chronons::seconds(3));
   timer1.wait();
   BOOST_ASIO_CHECK(count == 0);
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
   timer1.expires_at(timer1.expires_at() + chronons::seconds(2));
+#else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+  timer1.expires_at(timer1.expiry() + chronons::seconds(2));
+#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
   timer1.wait();
   BOOST_ASIO_CHECK(count == 1);
+#if defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
   timer1.expires_at(timer1.expires_at() + chronons::seconds(2));
+#else // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
+  timer1.expires_at(timer1.expiry() + chronons::seconds(2));
+#endif // defined(BOOST_ASIO_HAS_BOOST_DATE_TIME)
   timer1.wait();
   BOOST_ASIO_CHECK(count == 2);
 
@@ -166,12 +173,12 @@ void strand_test()
 
   count = 0;
   int exception_count = 0;
-  ios.reset();
-  s.post(throw_exception);
-  s.post(bindns::bind(increment, &count));
-  s.post(bindns::bind(increment, &count));
-  s.post(throw_exception);
-  s.post(bindns::bind(increment, &count));
+  ioc.restart();
+  post(s, throw_exception);
+  post(s, bindns::bind(increment, &count));
+  post(s, bindns::bind(increment, &count));
+  post(s, throw_exception);
+  post(s, bindns::bind(increment, &count));
 
   // No handlers can be called until run() is called.
   BOOST_ASIO_CHECK(count == 0);
@@ -181,7 +188,7 @@ void strand_test()
   {
     try
     {
-      ios.run();
+      ioc.run();
       break;
     }
     catch (int)
@@ -195,15 +202,15 @@ void strand_test()
   BOOST_ASIO_CHECK(exception_count == 2);
 
   count = 0;
-  ios.reset();
+  ioc.restart();
 
   // Check for clean shutdown when handlers posted through an orphaned strand
   // are abandoned.
   {
-    strand s2(ios);
-    s2.post(bindns::bind(increment, &count));
-    s2.post(bindns::bind(increment, &count));
-    s2.post(bindns::bind(increment, &count));
+    io_context::strand s2(ioc);
+    post(s2, bindns::bind(increment, &count));
+    post(s2, bindns::bind(increment, &count));
+    post(s2, bindns::bind(increment, &count));
   }
 
   // No handlers can be called until run() is called.
diff --git a/test/system_timer.cpp b/test/system_timer.cpp
index 38e53e2fa2..3b8f80cb5d 100644
--- a/test/system_timer.cpp
+++ b/test/system_timer.cpp
@@ -25,7 +25,8 @@
 
 #if defined(BOOST_ASIO_HAS_STD_CHRONO)
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/executor_work_guard.hpp>
+#include <boost/asio/io_context.hpp>
 #include <boost/asio/detail/thread.hpp>
 
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
@@ -40,8 +41,6 @@ namespace bindns = boost;
 namespace bindns = std;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-namespace chronons = std::chrono;
-
 void increment(int* count)
 {
   ++(*count);
@@ -55,7 +54,7 @@ void decrement_to_zero(boost::asio::system_timer* t, int* count)
 
     int before_value = *count;
 
-    t->expires_at(t->expires_at() + chronons::seconds(1));
+    t->expires_at(t->expiry() + boost::asio::chrono::seconds(1));
     t->async_wait(bindns::bind(decrement_to_zero, t, count));
 
     // Completion cannot nest, so count value should remain unchanged.
@@ -89,19 +88,19 @@ boost::asio::system_timer::time_point now()
 
 void system_timer_test()
 {
-  using chronons::seconds;
-  using chronons::microseconds;
+  using boost::asio::chrono::seconds;
+  using boost::asio::chrono::microseconds;
 #if !defined(BOOST_ASIO_HAS_BOOST_BIND)
   using std::placeholders::_1;
   using std::placeholders::_2;
 #endif // !defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
+  boost::asio::io_context ioc;
   int count = 0;
 
   boost::asio::system_timer::time_point start = now();
 
-  boost::asio::system_timer t1(ios, seconds(1));
+  boost::asio::system_timer t1(ioc, seconds(1));
   t1.wait();
 
   // The timer must block until after its expiry time.
@@ -111,7 +110,7 @@ void system_timer_test()
 
   start = now();
 
-  boost::asio::system_timer t2(ios, seconds(1) + microseconds(500000));
+  boost::asio::system_timer t2(ioc, seconds(1) + microseconds(500000));
   t2.wait();
 
   // The timer must block until after its expiry time.
@@ -119,7 +118,7 @@ void system_timer_test()
   expected_end = start + seconds(1) + microseconds(500000);
   BOOST_ASIO_CHECK(expected_end < end || expected_end == end);
 
-  t2.expires_at(t2.expires_at() + seconds(1));
+  t2.expires_at(t2.expiry() + seconds(1));
   t2.wait();
 
   // The timer must block until after its expiry time.
@@ -129,7 +128,7 @@ void system_timer_test()
 
   start = now();
 
-  t2.expires_from_now(seconds(1) + microseconds(200000));
+  t2.expires_after(seconds(1) + microseconds(200000));
   t2.wait();
 
   // The timer must block until after its expiry time.
@@ -139,13 +138,13 @@ void system_timer_test()
 
   start = now();
 
-  boost::asio::system_timer t3(ios, seconds(5));
+  boost::asio::system_timer t3(ioc, seconds(5));
   t3.async_wait(bindns::bind(increment, &count));
 
   // No completions can be delivered until run() is called.
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.run();
+  ioc.run();
 
   // The run() call will not return until all operations have finished, and
   // this should not be until after the timer's expiry time.
@@ -157,14 +156,14 @@ void system_timer_test()
   count = 3;
   start = now();
 
-  boost::asio::system_timer t4(ios, seconds(1));
+  boost::asio::system_timer t4(ioc, seconds(1));
   t4.async_wait(bindns::bind(decrement_to_zero, &t4, &count));
 
   // No completions can be delivered until run() is called.
   BOOST_ASIO_CHECK(count == 3);
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // The run() call will not return until all operations have finished, and
   // this should not be until after the timer's final expiry time.
@@ -176,16 +175,16 @@ void system_timer_test()
   count = 0;
   start = now();
 
-  boost::asio::system_timer t5(ios, seconds(10));
+  boost::asio::system_timer t5(ioc, seconds(10));
   t5.async_wait(bindns::bind(increment_if_not_cancelled, &count, _1));
-  boost::asio::system_timer t6(ios, seconds(1));
+  boost::asio::system_timer t6(ioc, seconds(1));
   t6.async_wait(bindns::bind(cancel_timer, &t5));
 
   // No completions can be delivered until run() is called.
   BOOST_ASIO_CHECK(count == 0);
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // The timer should have been cancelled, so count should not have changed.
   // The total run time should not have been much more than 1 second (and
@@ -199,8 +198,8 @@ void system_timer_test()
   // wait should run to completion and increment the counter.
   t5.async_wait(bindns::bind(increment_if_not_cancelled, &count, _1));
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // The timer should not have been cancelled, so count should have changed.
   // The total time since the timer was created should be more than 10 seconds.
@@ -215,14 +214,14 @@ void system_timer_test()
   // Start two waits on a timer, one of which will be cancelled. The one
   // which is not cancelled should still run to completion and increment the
   // counter.
-  boost::asio::system_timer t7(ios, seconds(3));
+  boost::asio::system_timer t7(ioc, seconds(3));
   t7.async_wait(bindns::bind(increment_if_not_cancelled, &count, _1));
   t7.async_wait(bindns::bind(increment_if_not_cancelled, &count, _1));
-  boost::asio::system_timer t8(ios, seconds(1));
+  boost::asio::system_timer t8(ioc, seconds(1));
   t8.async_wait(bindns::bind(cancel_one_timer, &t7));
 
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
 
   // One of the waits should not have been cancelled, so count should have
   // changed. The total time since the timer was created should be more than 3
@@ -233,26 +232,33 @@ void system_timer_test()
   BOOST_ASIO_CHECK(expected_end < end || expected_end == end);
 }
 
-void timer_handler(const boost::system::error_code&)
+struct timer_handler
 {
-}
+  timer_handler() {}
+  void operator()(const boost::system::error_code&) {}
+#if defined(BOOST_ASIO_HAS_MOVE)
+  timer_handler(timer_handler&&) {}
+private:
+  timer_handler(const timer_handler&);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+};
 
 void system_timer_cancel_test()
 {
-  static boost::asio::io_service io_service;
+  static boost::asio::io_context io_context;
   struct timer
   {
     boost::asio::system_timer t;
-    timer() : t(io_service)
+    timer() : t(io_context)
     {
       t.expires_at((boost::asio::system_timer::time_point::max)());
     }
   } timers[50];
 
-  timers[2].t.async_wait(&timer_handler);
-  timers[41].t.async_wait(&timer_handler);
+  timers[2].t.async_wait(timer_handler());
+  timers[41].t.async_wait(timer_handler());
   for (int i = 10; i < 20; ++i)
-    timers[i].t.async_wait(&timer_handler);
+    timers[i].t.async_wait(timer_handler());
 
   BOOST_ASIO_CHECK(timers[2].t.cancel() == 1);
   BOOST_ASIO_CHECK(timers[41].t.cancel() == 1);
@@ -283,11 +289,11 @@ void asio_handler_deallocate(void* pointer, std::size_t,
 
 void system_timer_custom_allocation_test()
 {
-  static boost::asio::io_service io_service;
+  static boost::asio::io_context io_context;
   struct timer
   {
     boost::asio::system_timer t;
-    timer() : t(io_service) {}
+    timer() : t(io_context) {}
   } timers[100];
 
   int allocation_count = 0;
@@ -307,41 +313,75 @@ void system_timer_custom_allocation_test()
   for (int i = 0; i < 50; ++i)
     timers[i].t.cancel();
 
-  io_service.run();
+  io_context.run();
 
   BOOST_ASIO_CHECK(allocation_count == 0);
 }
 
-void io_service_run(boost::asio::io_service* ios)
+void io_context_run(boost::asio::io_context* ioc)
 {
-  ios->run();
+  ioc->run();
 }
 
 void system_timer_thread_test()
 {
-  boost::asio::io_service ios;
-  boost::asio::io_service::work w(ios);
-  boost::asio::system_timer t1(ios);
-  boost::asio::system_timer t2(ios);
+  boost::asio::io_context ioc;
+  boost::asio::executor_work_guard<boost::asio::io_context::executor_type> work
+    = boost::asio::make_work_guard(ioc);
+  boost::asio::system_timer t1(ioc);
+  boost::asio::system_timer t2(ioc);
   int count = 0;
 
-  boost::asio::detail::thread th(bindns::bind(io_service_run, &ios));
+  boost::asio::detail::thread th(bindns::bind(io_context_run, &ioc));
 
-  t2.expires_from_now(chronons::seconds(2));
+  t2.expires_after(boost::asio::chrono::seconds(2));
   t2.wait();
 
-  t1.expires_from_now(chronons::seconds(2));
+  t1.expires_after(boost::asio::chrono::seconds(2));
   t1.async_wait(bindns::bind(increment, &count));
 
-  t2.expires_from_now(chronons::seconds(4));
+  t2.expires_after(boost::asio::chrono::seconds(4));
   t2.wait();
 
-  ios.stop();
+  ioc.stop();
   th.join();
 
   BOOST_ASIO_CHECK(count == 1);
 }
 
+#if defined(BOOST_ASIO_HAS_MOVE)
+boost::asio::system_timer make_timer(boost::asio::io_context& ioc, int* count)
+{
+  boost::asio::system_timer t(ioc);
+  t.expires_after(boost::asio::chrono::seconds(1));
+  t.async_wait(bindns::bind(increment, count));
+  return t;
+}
+#endif
+
+void system_timer_move_test()
+{
+#if defined(BOOST_ASIO_HAS_MOVE)
+  boost::asio::io_context io_context1;
+  boost::asio::io_context io_context2;
+  int count = 0;
+
+  boost::asio::system_timer t1 = make_timer(io_context1, &count);
+  boost::asio::system_timer t2 = make_timer(io_context2, &count);
+  boost::asio::system_timer t3 = std::move(t1);
+
+  t2 = std::move(t1);
+
+  io_context2.run();
+
+  BOOST_ASIO_CHECK(count == 1);
+
+  io_context1.run();
+
+  BOOST_ASIO_CHECK(count == 2);
+#endif // defined(BOOST_ASIO_HAS_MOVE)
+}
+
 BOOST_ASIO_TEST_SUITE
 (
   "system_timer",
@@ -349,6 +389,7 @@ BOOST_ASIO_TEST_SUITE
   BOOST_ASIO_TEST_CASE(system_timer_cancel_test)
   BOOST_ASIO_TEST_CASE(system_timer_custom_allocation_test)
   BOOST_ASIO_TEST_CASE(system_timer_thread_test)
+  BOOST_ASIO_TEST_CASE(system_timer_move_test)
 )
 #else // defined(BOOST_ASIO_HAS_STD_CHRONO)
 BOOST_ASIO_TEST_SUITE
diff --git a/test/use_future.cpp b/test/use_future.cpp
new file mode 100644
index 0000000000..7e773c176e
--- /dev/null
+++ b/test/use_future.cpp
@@ -0,0 +1,1346 @@
+//
+// use_future.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/use_future.hpp>
+
+#include <string>
+#include "unit_test.hpp"
+
+#if defined(BOOST_ASIO_HAS_STD_FUTURE)
+
+#include "archetypes/async_ops.hpp"
+#include "archetypes/deprecated_async_ops.hpp"
+
+void use_future_0_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<void> f;
+
+  f = async_op_0(use_future);
+  try
+  {
+    f.get();
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_0(true, use_future);
+  try
+  {
+    f.get();
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_0(false, use_future);
+  try
+  {
+    f.get();
+    BOOST_ASIO_CHECK(false);
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_0(true, use_future);
+  try
+  {
+    f.get();
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_0(false, use_future);
+  try
+  {
+    f.get();
+    BOOST_ASIO_CHECK(false);
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+void use_future_1_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+
+  f = async_op_1(use_future);
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_1(true, use_future);
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_1(false, use_future);
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)i;
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_1(true, use_future);
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_1(false, use_future);
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)i;
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+void use_future_2_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<std::tuple<int, double>> f;
+
+  f = async_op_2(use_future);
+  try
+  {
+    int i;
+    double d;
+    std::tie(i, d) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_2(true, use_future);
+  try
+  {
+    int i;
+    double d;
+    std::tie(i, d) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_2(false, use_future);
+  try
+  {
+    std::tuple<int, double> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_2(true, use_future);
+  try
+  {
+    int i;
+    double d;
+    std::tie(i, d) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_2(false, use_future);
+  try
+  {
+    std::tuple<int, double> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+void use_future_3_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<std::tuple<int, double, char>> f;
+
+  f = async_op_3(use_future);
+  try
+  {
+    int i;
+    double d;
+    char c;
+    std::tie(i, d, c) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+    BOOST_ASIO_CHECK(c == 'a');
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_3(true, use_future);
+  try
+  {
+    int i;
+    double d;
+    char c;
+    std::tie(i, d, c) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+    BOOST_ASIO_CHECK(c == 'a');
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_3(false, use_future);
+  try
+  {
+    std::tuple<int, double, char> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_3(true, use_future);
+  try
+  {
+    int i;
+    double d;
+    char c;
+    std::tie(i, d, c) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+    BOOST_ASIO_CHECK(c == 'a');
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_3(false, use_future);
+  try
+  {
+    std::tuple<int, double, char> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+int package_0()
+{
+  return 42;
+}
+
+int package_ec_0(boost::system::error_code ec)
+{
+  return ec ? 0 : 42;
+}
+
+int package_ex_0(std::exception_ptr ex)
+{
+  return ex ? 0 : 42;
+}
+
+void use_future_package_0_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+
+  f = async_op_0(use_future(package_0));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_0(true, use_future(&package_ec_0));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_0(false, use_future(package_ec_0));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_0(true, use_future(package_ex_0));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_0(false, use_future(package_ex_0));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+int package_1(int i)
+{
+  return i;
+}
+
+int package_ec_1(boost::system::error_code ec, int i)
+{
+  return ec ? 0 : i;
+}
+
+int package_ex_1(std::exception_ptr ex, int i)
+{
+  return ex ? 0 : i;
+}
+
+void use_future_package_1_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+
+  f = async_op_1(use_future(package_1));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_1(true, use_future(package_ec_1));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_1(false, use_future(package_ec_1));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_1(true, use_future(package_ex_1));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_1(false, use_future(package_ex_1));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+int package_2(int i, double)
+{
+  return i;
+}
+
+int package_ec_2(boost::system::error_code ec, int i, double)
+{
+  return ec ? 0 : i;
+}
+
+int package_ex_2(std::exception_ptr ex, int i, double)
+{
+  return ex ? 0 : i;
+}
+
+void use_future_package_2_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+
+  f = async_op_2(use_future(package_2));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_2(true, use_future(package_ec_2));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_2(false, use_future(package_ec_2));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_2(true, use_future(package_ex_2));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_2(false, use_future(package_ex_2));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+int package_3(int i, double, char)
+{
+  return i;
+}
+
+int package_ec_3(boost::system::error_code ec, int i, double, char)
+{
+  return ec ? 0 : i;
+}
+
+int package_ex_3(std::exception_ptr ex, int i, double, char)
+{
+  return ex ? 0 : i;
+}
+
+void use_future_package_3_test()
+{
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+
+  f = async_op_3(use_future(package_3));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_3(true, use_future(package_ec_3));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ec_3(false, use_future(package_ec_3));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_3(true, use_future(package_ex_3));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_3(false, use_future(package_ex_3));
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+}
+
+void deprecated_use_future_0_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<void> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_0(ctx, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    f.get();
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_0(ctx, true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    f.get();
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_0(ctx, false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    f.get();
+    BOOST_ASIO_CHECK(false);
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_0(true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    f.get();
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = async_op_ex_0(false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    f.get();
+    BOOST_ASIO_CHECK(false);
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+void deprecated_use_future_1_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_1(ctx, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_1(ctx, true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_1(ctx, false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)i;
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_1(ctx, true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_1(ctx, false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)i;
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+void deprecated_use_future_2_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<std::tuple<int, double>> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_2(ctx, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i;
+    double d;
+    std::tie(i, d) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_2(ctx, true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i;
+    double d;
+    std::tie(i, d) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_2(ctx, false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    std::tuple<int, double> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_2(ctx, true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i;
+    double d;
+    std::tie(i, d) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_2(ctx, false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    std::tuple<int, double> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+void deprecated_use_future_3_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<std::tuple<int, double, char>> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_3(ctx, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i;
+    double d;
+    char c;
+    std::tie(i, d, c) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+    BOOST_ASIO_CHECK(c == 'a');
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_3(ctx, true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i;
+    double d;
+    char c;
+    std::tie(i, d, c) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+    BOOST_ASIO_CHECK(c == 'a');
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_3(ctx, false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    std::tuple<int, double, char> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (boost::system::system_error& e)
+  {
+    BOOST_ASIO_CHECK(e.code() == boost::asio::error::operation_aborted);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_3(ctx, true, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i;
+    double d;
+    char c;
+    std::tie(i, d, c) = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+    BOOST_ASIO_CHECK(d == 2.0);
+    BOOST_ASIO_CHECK(c == 'a');
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_3(ctx, false, use_future);
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    std::tuple<int, double, char> t = f.get();
+    BOOST_ASIO_CHECK(false);
+    (void)t;
+  }
+  catch (std::exception& e)
+  {
+    BOOST_ASIO_CHECK(e.what() == std::string("blah"));
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+void deprecated_use_future_package_0_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_0(ctx, use_future(package_0));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_0(ctx, true, use_future(&package_ec_0));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_0(ctx, false, use_future(package_ec_0));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_0(ctx, true, use_future(package_ex_0));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_0(ctx, false, use_future(package_ex_0));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+void deprecated_use_future_package_1_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_1(ctx, use_future(package_1));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_1(ctx, true, use_future(package_ec_1));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_1(ctx, false, use_future(package_ec_1));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_1(ctx, true, use_future(package_ex_1));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_1(ctx, false, use_future(package_ex_1));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+void deprecated_use_future_package_2_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_2(ctx, use_future(package_2));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_2(ctx, true, use_future(package_ec_2));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_2(ctx, false, use_future(package_ec_2));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_2(ctx, true, use_future(package_ex_2));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_2(ctx, false, use_future(package_ex_2));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+void deprecated_use_future_package_3_test()
+{
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+  using boost::asio::use_future;
+  using namespace archetypes;
+
+  std::future<int> f;
+  boost::asio::io_context ctx;
+
+  f = deprecated_async_op_3(ctx, use_future(package_3));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_3(ctx, true, use_future(package_ec_3));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ec_3(ctx, false, use_future(package_ec_3));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_3(ctx, true, use_future(package_ex_3));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 42);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+
+  f = deprecated_async_op_ex_3(ctx, false, use_future(package_ex_3));
+  ctx.restart();
+  ctx.run();
+  try
+  {
+    int i = f.get();
+    BOOST_ASIO_CHECK(i == 0);
+  }
+  catch (...)
+  {
+    BOOST_ASIO_CHECK(false);
+  }
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+}
+
+BOOST_ASIO_TEST_SUITE
+(
+  "use_future",
+  BOOST_ASIO_TEST_CASE(use_future_0_test)
+  BOOST_ASIO_TEST_CASE(use_future_1_test)
+  BOOST_ASIO_TEST_CASE(use_future_2_test)
+  BOOST_ASIO_TEST_CASE(use_future_3_test)
+  BOOST_ASIO_TEST_CASE(use_future_package_0_test)
+  BOOST_ASIO_TEST_CASE(use_future_package_1_test)
+  BOOST_ASIO_TEST_CASE(use_future_package_2_test)
+  BOOST_ASIO_TEST_CASE(use_future_package_3_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_0_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_1_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_2_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_3_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_package_0_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_package_1_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_package_2_test)
+  BOOST_ASIO_TEST_CASE(deprecated_use_future_package_3_test)
+)
+
+#else // defined(BOOST_ASIO_HAS_STD_FUTURE)
+
+BOOST_ASIO_TEST_SUITE
+(
+  "use_future",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
+
+#endif // defined(BOOST_ASIO_HAS_STD_FUTURE)
diff --git a/test/uses_executor.cpp b/test/uses_executor.cpp
new file mode 100644
index 0000000000..d12f3d5bb0
--- /dev/null
+++ b/test/uses_executor.cpp
@@ -0,0 +1,25 @@
+//
+// uses_executor.cpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/uses_executor.hpp>
+
+#include "unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "uses_executor",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/windows/object_handle.cpp b/test/windows/object_handle.cpp
index 8b0f10b608..243542b4da 100644
--- a/test/windows/object_handle.cpp
+++ b/test/windows/object_handle.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/windows/object_handle.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../archetypes/async_result.hpp"
 #include "../unit_test.hpp"
 
@@ -42,15 +42,15 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     archetypes::lazy_handler lazy;
     boost::system::error_code ec;
 
     // basic_object_handle constructors.
 
-    win::object_handle handle1(ios);
+    win::object_handle handle1(ioc);
     HANDLE native_handle1 = INVALID_HANDLE_VALUE;
-    win::object_handle handle2(ios, native_handle1);
+    win::object_handle handle2(ioc, native_handle1);
 
 #if defined(BOOST_ASIO_HAS_MOVE)
     win::object_handle handle3(std::move(handle2));
@@ -59,14 +59,19 @@ void test()
     // basic_object_handle operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    handle1 = win::object_handle(ios);
+    handle1 = win::object_handle(ioc);
     handle1 = std::move(handle2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = handle1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = handle1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    io_context::executor_type ex = handle1.get_executor();
+    (void)ex;
 
     // basic_handle functions.
 
diff --git a/test/windows/overlapped_handle.cpp b/test/windows/overlapped_handle.cpp
new file mode 100644
index 0000000000..4b3f79cc7b
--- /dev/null
+++ b/test/windows/overlapped_handle.cpp
@@ -0,0 +1,26 @@
+//
+// overlapped_handle.cpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Disable autolinking for unit tests.
+#if !defined(BOOST_ALL_NO_LIB)
+#define BOOST_ALL_NO_LIB 1
+#endif // !defined(BOOST_ALL_NO_LIB)
+
+// Test that header file is self-contained.
+#include <boost/asio/windows/overlapped_handle.hpp>
+
+#include <boost/asio.hpp>
+#include "../unit_test.hpp"
+
+BOOST_ASIO_TEST_SUITE
+(
+  "windows/overlapped_handle",
+  BOOST_ASIO_TEST_CASE(null_test)
+)
diff --git a/test/windows/overlapped_ptr.cpp b/test/windows/overlapped_ptr.cpp
index 806fc5c567..c6cf8fee98 100644
--- a/test/windows/overlapped_ptr.cpp
+++ b/test/windows/overlapped_ptr.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/windows/overlapped_ptr.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../unit_test.hpp"
 
 //------------------------------------------------------------------------------
@@ -48,21 +48,21 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
 
     // basic_overlapped_ptr constructors.
 
     win::overlapped_ptr ptr1;
 
-    win::overlapped_ptr ptr2(ios, &overlapped_handler_1);
-    win::overlapped_ptr ptr3(ios, overlapped_handler_2());
+    win::overlapped_ptr ptr2(ioc, &overlapped_handler_1);
+    win::overlapped_ptr ptr3(ioc, overlapped_handler_2());
 
     // overlapped_ptr functions.
 
     ptr1.reset();
 
-    ptr2.reset(ios, &overlapped_handler_1);
-    ptr3.reset(ios, overlapped_handler_2());
+    ptr2.reset(ioc, &overlapped_handler_1);
+    ptr3.reset(ioc, overlapped_handler_2());
 
     OVERLAPPED* ov1 = ptr1.get();
     (void)ov1;
diff --git a/test/windows/random_access_handle.cpp b/test/windows/random_access_handle.cpp
index 856a848022..fd2116d502 100644
--- a/test/windows/random_access_handle.cpp
+++ b/test/windows/random_access_handle.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/windows/random_access_handle.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../archetypes/async_result.hpp"
 #include "../unit_test.hpp"
 
@@ -46,7 +46,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     boost::asio::uint64_t offset = 0;
@@ -55,9 +55,9 @@ void test()
 
     // basic_random_access_handle constructors.
 
-    win::random_access_handle handle1(ios);
+    win::random_access_handle handle1(ioc);
     HANDLE native_handle1 = INVALID_HANDLE_VALUE;
-    win::random_access_handle handle2(ios, native_handle1);
+    win::random_access_handle handle2(ioc, native_handle1);
 
 #if defined(BOOST_ASIO_HAS_MOVE)
     win::random_access_handle handle3(std::move(handle2));
@@ -66,14 +66,19 @@ void test()
     // basic_random_access_handle operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    handle1 = win::random_access_handle(ios);
+    handle1 = win::random_access_handle(ioc);
     handle1 = std::move(handle2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = handle1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = handle1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    io_context::executor_type ex = handle1.get_executor();
+    (void)ex;
 
     // basic_handle functions.
 
@@ -95,12 +100,9 @@ void test()
     handle1.close();
     handle1.close(ec);
 
-    win::random_access_handle::native_type native_handle3 = handle1.native();
-    (void)native_handle3;
-
-    win::random_access_handle::native_handle_type native_handle4
+    win::random_access_handle::native_handle_type native_handle3
       = handle1.native_handle();
-    (void)native_handle4;
+    (void)native_handle3;
 
     handle1.cancel();
     handle1.cancel(ec);
diff --git a/test/windows/stream_handle.cpp b/test/windows/stream_handle.cpp
index 4a18636489..af44e6a1f2 100644
--- a/test/windows/stream_handle.cpp
+++ b/test/windows/stream_handle.cpp
@@ -16,7 +16,7 @@
 // Test that header file is self-contained.
 #include <boost/asio/windows/stream_handle.hpp>
 
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
 #include "../archetypes/async_result.hpp"
 #include "../unit_test.hpp"
 
@@ -46,7 +46,7 @@ void test()
 
   try
   {
-    io_service ios;
+    io_context ioc;
     char mutable_char_buffer[128] = "";
     const char const_char_buffer[128] = "";
     archetypes::lazy_handler lazy;
@@ -54,9 +54,9 @@ void test()
 
     // basic_stream_handle constructors.
 
-    win::stream_handle handle1(ios);
+    win::stream_handle handle1(ioc);
     HANDLE native_handle1 = INVALID_HANDLE_VALUE;
-    win::stream_handle handle2(ios, native_handle1);
+    win::stream_handle handle2(ioc, native_handle1);
 
 #if defined(BOOST_ASIO_HAS_MOVE)
     win::stream_handle handle3(std::move(handle2));
@@ -65,14 +65,19 @@ void test()
     // basic_stream_handle operators.
 
 #if defined(BOOST_ASIO_HAS_MOVE)
-    handle1 = win::stream_handle(ios);
+    handle1 = win::stream_handle(ioc);
     handle1 = std::move(handle2);
 #endif // defined(BOOST_ASIO_HAS_MOVE)
 
     // basic_io_object functions.
 
-    io_service& ios_ref = handle1.get_io_service();
-    (void)ios_ref;
+#if !defined(BOOST_ASIO_NO_DEPRECATED)
+    io_context& ioc_ref = handle1.get_io_context();
+    (void)ioc_ref;
+#endif // !defined(BOOST_ASIO_NO_DEPRECATED)
+
+    io_context::executor_type ex = handle1.get_executor();
+    (void)ex;
 
     // basic_handle functions.
 
@@ -94,12 +99,9 @@ void test()
     handle1.close();
     handle1.close(ec);
 
-    win::stream_handle::native_type native_handle3 = handle1.native();
-    (void)native_handle3;
-
-    win::stream_handle::native_handle_type native_handle4
+    win::stream_handle::native_handle_type native_handle3
       = handle1.native_handle();
-    (void)native_handle4;
+    (void)native_handle3;
 
     handle1.cancel();
     handle1.cancel(ec);
diff --git a/test/write.cpp b/test/write.cpp
index 36535cea5f..0e68e82e60 100644
--- a/test/write.cpp
+++ b/test/write.cpp
@@ -19,7 +19,8 @@
 #include <cstring>
 #include <vector>
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/streambuf.hpp>
 #include "unit_test.hpp"
 
@@ -42,10 +43,10 @@ using namespace std; // For memcmp, memcpy and memset.
 class test_stream
 {
 public:
-  typedef boost::asio::io_service io_service_type;
+  typedef boost::asio::io_context::executor_type executor_type;
 
-  test_stream(boost::asio::io_service& io_service)
-    : io_service_(io_service),
+  test_stream(boost::asio::io_context& io_context)
+    : io_context_(io_context),
       length_(max_length),
       position_(0),
       next_write_length_(max_length)
@@ -53,9 +54,9 @@ class test_stream
     memset(data_, 0, max_length);
   }
 
-  io_service_type& get_io_service()
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
   {
-    return io_service_;
+    return io_context_.get_executor();
   }
 
   void reset(size_t length = max_length)
@@ -73,22 +74,20 @@ class test_stream
     next_write_length_ = length;
   }
 
-  template <typename Const_Buffers>
-  bool check_buffers(const Const_Buffers& buffers, size_t length)
+  template <typename Iterator>
+  bool check_buffers(Iterator begin, Iterator end, size_t length)
   {
     if (length != position_)
       return false;
 
-    typename Const_Buffers::const_iterator iter = buffers.begin();
-    typename Const_Buffers::const_iterator end = buffers.end();
+    Iterator iter = begin;
     size_t checked_length = 0;
     for (; iter != end && checked_length < length; ++iter)
     {
       size_t buffer_length = boost::asio::buffer_size(*iter);
       if (buffer_length > length - checked_length)
         buffer_length = length - checked_length;
-      if (memcmp(data_ + checked_length,
-            boost::asio::buffer_cast<const void*>(*iter), buffer_length) != 0)
+      if (memcmp(data_ + checked_length, iter->data(), buffer_length) != 0)
         return false;
       checked_length += buffer_length;
     }
@@ -96,6 +95,13 @@ class test_stream
     return true;
   }
 
+  template <typename Const_Buffers>
+  bool check_buffers(const Const_Buffers& buffers, size_t length)
+  {
+    return check_buffers(boost::asio::buffer_sequence_begin(buffers),
+        boost::asio::buffer_sequence_end(buffers), length);
+  }
+
   template <typename Const_Buffers>
   size_t write_some(const Const_Buffers& buffers)
   {
@@ -117,12 +123,14 @@ class test_stream
   void async_write_some(const Const_Buffers& buffers, Handler handler)
   {
     size_t bytes_transferred = write_some(buffers);
-    io_service_.post(boost::asio::detail::bind_handler(
-          handler, boost::system::error_code(), bytes_transferred));
+    boost::asio::post(get_executor(),
+        boost::asio::detail::bind_handler(
+          BOOST_ASIO_MOVE_CAST(Handler)(handler),
+          boost::system::error_code(), bytes_transferred));
   }
 
 private:
-  io_service_type& io_service_;
+  boost::asio::io_context& io_context_;
   enum { max_length = 8192 };
   char data_[max_length];
   size_t length_;
@@ -137,19 +145,19 @@ static char mutable_write_data[]
 
 void test_2_arg_zero_buffers_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
 
   size_t bytes_transferred = boost::asio::write(s, buffers);
   BOOST_ASIO_CHECK(bytes_transferred == 0);
 }
 
-void test_2_arg_const_buffers_1_write()
+void test_2_arg_const_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -170,11 +178,11 @@ void test_2_arg_const_buffers_1_write()
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
-void test_2_arg_mutable_buffers_1_write()
+void test_2_arg_mutable_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -197,11 +205,12 @@ void test_2_arg_mutable_buffers_1_write()
 
 void test_2_arg_vector_buffers_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
-  buffers.push_back(boost::asio::buffer(write_data) + 32);
+  buffers.push_back(boost::asio::buffer(write_data, 39) + 32);
+  buffers.push_back(boost::asio::buffer(write_data) + 39);
 
   s.reset();
   size_t bytes_transferred = boost::asio::write(s, buffers);
@@ -223,8 +232,8 @@ void test_2_arg_vector_buffers_write()
 
 void test_3_arg_nothrow_zero_buffers_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
 
   boost::system::error_code error;
@@ -233,11 +242,11 @@ void test_3_arg_nothrow_zero_buffers_write()
   BOOST_ASIO_CHECK(!error);
 }
 
-void test_3_arg_nothrow_const_buffers_1_write()
+void test_3_arg_nothrow_const_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -262,11 +271,11 @@ void test_3_arg_nothrow_const_buffers_1_write()
   BOOST_ASIO_CHECK(!error);
 }
 
-void test_3_arg_nothrow_mutable_buffers_1_write()
+void test_3_arg_nothrow_mutable_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -293,11 +302,12 @@ void test_3_arg_nothrow_mutable_buffers_1_write()
 
 void test_3_arg_nothrow_vector_buffers_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
-  buffers.push_back(boost::asio::buffer(write_data) + 32);
+  buffers.push_back(boost::asio::buffer(write_data, 39) + 32);
+  buffers.push_back(boost::asio::buffer(write_data) + 39);
 
   s.reset();
   boost::system::error_code error;
@@ -333,11 +343,11 @@ size_t short_transfer(const boost::system::error_code& ec,
   return !!ec ? 0 : 3;
 }
 
-void test_3_arg_const_buffers_1_write()
+void test_3_arg_const_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -515,11 +525,11 @@ void test_3_arg_const_buffers_1_write()
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
-void test_3_arg_mutable_buffers_1_write()
+void test_3_arg_mutable_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -699,11 +709,12 @@ void test_3_arg_mutable_buffers_1_write()
 
 void test_3_arg_vector_buffers_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
-  buffers.push_back(boost::asio::buffer(write_data) + 32);
+  buffers.push_back(boost::asio::buffer(write_data, 39) + 32);
+  buffers.push_back(boost::asio::buffer(write_data) + 39);
 
   s.reset();
   size_t bytes_transferred = boost::asio::write(s, buffers,
@@ -880,11 +891,11 @@ void test_3_arg_vector_buffers_write()
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
-void test_4_arg_const_buffers_1_write()
+void test_4_arg_const_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -1117,11 +1128,11 @@ void test_4_arg_const_buffers_1_write()
   BOOST_ASIO_CHECK(!error);
 }
 
-void test_4_arg_mutable_buffers_1_write()
+void test_4_arg_mutable_buffer_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -1356,11 +1367,12 @@ void test_4_arg_mutable_buffers_1_write()
 
 void test_4_arg_vector_buffers_write()
 {
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
-  buffers.push_back(boost::asio::buffer(write_data) + 32);
+  buffers.push_back(boost::asio::buffer(write_data, 39) + 32);
+  buffers.push_back(boost::asio::buffer(write_data) + 39);
 
   s.reset();
   boost::system::error_code error;
@@ -1600,7 +1612,7 @@ void async_write_handler(const boost::system::error_code& e,
   BOOST_ASIO_CHECK(bytes_transferred == expected_bytes_transferred);
 }
 
-void test_3_arg_const_buffers_1_async_write()
+void test_3_arg_const_buffer_async_write()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -1610,9 +1622,9 @@ void test_3_arg_const_buffers_1_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -1620,8 +1632,8 @@ void test_3_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1631,8 +1643,8 @@ void test_3_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1642,20 +1654,20 @@ void test_3_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
   s.reset();
   int i = boost::asio::async_write(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
-void test_3_arg_mutable_buffers_1_async_write()
+void test_3_arg_mutable_buffer_async_write()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -1665,9 +1677,9 @@ void test_3_arg_mutable_buffers_1_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -1675,8 +1687,8 @@ void test_3_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -1686,8 +1698,8 @@ void test_3_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -1697,16 +1709,16 @@ void test_3_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
   s.reset();
   int i = boost::asio::async_write(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 }
 
@@ -1721,8 +1733,8 @@ void test_3_arg_boost_array_buffers_async_write()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -1732,8 +1744,8 @@ void test_3_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1743,8 +1755,8 @@ void test_3_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1754,16 +1766,16 @@ void test_3_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
   s.reset();
   int i = boost::asio::async_write(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -1779,8 +1791,8 @@ void test_3_arg_std_array_buffers_async_write()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -1790,8 +1802,8 @@ void test_3_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1801,8 +1813,8 @@ void test_3_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1812,16 +1824,16 @@ void test_3_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
   s.reset();
   int i = boost::asio::async_write(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -1836,19 +1848,20 @@ void test_3_arg_vector_buffers_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
-  buffers.push_back(boost::asio::buffer(write_data) + 32);
+  buffers.push_back(boost::asio::buffer(write_data, 39) + 32);
+  buffers.push_back(boost::asio::buffer(write_data) + 39);
 
   s.reset();
   bool called = false;
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1858,8 +1871,8 @@ void test_3_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1869,16 +1882,16 @@ void test_3_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
   s.reset();
   int i = boost::asio::async_write(s, buffers, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
@@ -1892,10 +1905,10 @@ void test_3_arg_streambuf_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb;
-  boost::asio::const_buffers_1 buffers
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -1905,8 +1918,8 @@ void test_3_arg_streambuf_async_write()
   boost::asio::async_write(s, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1918,8 +1931,8 @@ void test_3_arg_streambuf_async_write()
   boost::asio::async_write(s, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1931,8 +1944,8 @@ void test_3_arg_streambuf_async_write()
   boost::asio::async_write(s, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1941,12 +1954,12 @@ void test_3_arg_streambuf_async_write()
   sb.sputn(write_data, sizeof(write_data));
   int i = boost::asio::async_write(s, sb, archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
-void test_4_arg_const_buffers_1_async_write()
+void test_4_arg_const_buffer_async_write()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -1956,9 +1969,9 @@ void test_4_arg_const_buffers_1_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -1966,8 +1979,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1977,8 +1990,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1988,8 +2001,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -1998,8 +2011,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2009,8 +2022,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2020,8 +2033,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2030,8 +2043,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2041,8 +2054,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2052,8 +2065,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2062,8 +2075,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2073,8 +2086,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2084,8 +2097,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -2094,8 +2107,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2105,8 +2118,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2116,8 +2129,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2126,8 +2139,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2137,8 +2150,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2148,8 +2161,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2158,8 +2171,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2169,8 +2182,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2180,8 +2193,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2190,8 +2203,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2201,8 +2214,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2212,8 +2225,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2222,8 +2235,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2233,8 +2246,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2244,8 +2257,8 @@ void test_4_arg_const_buffers_1_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2253,12 +2266,12 @@ void test_4_arg_const_buffers_1_async_write()
   int i = boost::asio::async_write(s, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
-void test_4_arg_mutable_buffers_1_async_write()
+void test_4_arg_mutable_buffer_async_write()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -2268,9 +2281,9 @@ void test_4_arg_mutable_buffers_1_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -2278,8 +2291,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2289,8 +2302,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2300,8 +2313,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2310,8 +2323,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2321,8 +2334,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2332,8 +2345,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2342,8 +2355,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2353,8 +2366,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2364,8 +2377,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2374,8 +2387,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2385,8 +2398,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2396,8 +2409,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -2406,8 +2419,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2417,8 +2430,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2428,8 +2441,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2438,8 +2451,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2449,8 +2462,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2460,8 +2473,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2470,8 +2483,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2481,8 +2494,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2492,8 +2505,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2502,8 +2515,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2513,8 +2526,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2524,8 +2537,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2534,8 +2547,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2545,8 +2558,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2556,8 +2569,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(mutable_write_data)));
 
@@ -2565,8 +2578,8 @@ void test_4_arg_mutable_buffers_1_async_write()
   int i = boost::asio::async_write(s, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
@@ -2581,8 +2594,8 @@ void test_4_arg_boost_array_buffers_async_write()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -2592,8 +2605,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2603,8 +2616,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2614,8 +2627,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2624,8 +2637,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2635,8 +2648,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2646,8 +2659,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2656,8 +2669,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2667,8 +2680,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2678,8 +2691,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2688,8 +2701,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2699,8 +2712,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2710,8 +2723,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -2720,8 +2733,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2731,8 +2744,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2742,8 +2755,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2752,8 +2765,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2763,8 +2776,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2774,8 +2787,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2784,8 +2797,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2795,8 +2808,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2806,8 +2819,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -2816,8 +2829,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2827,8 +2840,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2838,8 +2851,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2848,8 +2861,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2859,8 +2872,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2870,8 +2883,8 @@ void test_4_arg_boost_array_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2879,8 +2892,8 @@ void test_4_arg_boost_array_buffers_async_write()
   int i = boost::asio::async_write(s, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -2896,8 +2909,8 @@ void test_4_arg_std_array_buffers_async_write()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -2907,8 +2920,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2918,8 +2931,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2929,8 +2942,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2939,8 +2952,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2950,8 +2963,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -2961,8 +2974,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2971,8 +2984,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -2982,8 +2995,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -2993,8 +3006,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3003,8 +3016,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3014,8 +3027,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3025,8 +3038,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -3035,8 +3048,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3046,8 +3059,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3057,8 +3070,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3067,8 +3080,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3078,8 +3091,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3089,8 +3102,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3099,8 +3112,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3110,8 +3123,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3121,8 +3134,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3131,8 +3144,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3142,8 +3155,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3153,8 +3166,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3163,8 +3176,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3174,8 +3187,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3185,8 +3198,8 @@ void test_4_arg_std_array_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3194,8 +3207,8 @@ void test_4_arg_std_array_buffers_async_write()
   int i = boost::asio::async_write(s, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -3210,19 +3223,20 @@ void test_4_arg_vector_buffers_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
-  buffers.push_back(boost::asio::buffer(write_data) + 32);
+  buffers.push_back(boost::asio::buffer(write_data, 39) + 32);
+  buffers.push_back(boost::asio::buffer(write_data) + 39);
 
   s.reset();
   bool called = false;
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3232,8 +3246,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3243,8 +3257,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3253,8 +3267,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3264,8 +3278,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3275,8 +3289,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3285,8 +3299,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3296,8 +3310,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3307,8 +3321,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3317,8 +3331,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3328,8 +3342,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3339,8 +3353,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -3349,8 +3363,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3360,8 +3374,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3371,8 +3385,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3381,8 +3395,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3392,8 +3406,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3403,8 +3417,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3413,8 +3427,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3424,8 +3438,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3435,8 +3449,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3445,8 +3459,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3456,8 +3470,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3467,8 +3481,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3477,8 +3491,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3488,8 +3502,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3499,8 +3513,8 @@ void test_4_arg_vector_buffers_async_write()
   boost::asio::async_write(s, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3508,8 +3522,8 @@ void test_4_arg_vector_buffers_async_write()
   int i = boost::asio::async_write(s, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
@@ -3523,10 +3537,10 @@ void test_4_arg_streambuf_async_write()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_stream s(ios);
+  boost::asio::io_context ioc;
+  test_stream s(ioc);
   boost::asio::streambuf sb;
-  boost::asio::const_buffers_1 buffers
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -3536,8 +3550,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3549,8 +3563,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3562,8 +3576,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3574,8 +3588,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3587,8 +3601,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3600,8 +3614,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3612,8 +3626,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3625,8 +3639,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3638,8 +3652,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3650,8 +3664,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3663,8 +3677,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3676,8 +3690,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 50));
 
@@ -3688,8 +3702,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3701,8 +3715,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3714,8 +3728,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 1));
 
@@ -3726,8 +3740,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3739,8 +3753,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3752,8 +3766,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 10));
 
@@ -3764,8 +3778,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3777,8 +3791,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3790,8 +3804,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, 42));
 
@@ -3802,8 +3816,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3815,8 +3829,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3828,8 +3842,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3840,8 +3854,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3853,8 +3867,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3866,8 +3880,8 @@ void test_4_arg_streambuf_async_write()
   boost::asio::async_write(s, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 
@@ -3877,8 +3891,8 @@ void test_4_arg_streambuf_async_write()
   int i = boost::asio::async_write(s, sb, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(buffers, sizeof(write_data)));
 }
 
@@ -3886,27 +3900,27 @@ BOOST_ASIO_TEST_SUITE
 (
   "write",
   BOOST_ASIO_TEST_CASE(test_2_arg_zero_buffers_write)
-  BOOST_ASIO_TEST_CASE(test_2_arg_const_buffers_1_write)
-  BOOST_ASIO_TEST_CASE(test_2_arg_mutable_buffers_1_write)
+  BOOST_ASIO_TEST_CASE(test_2_arg_const_buffer_write)
+  BOOST_ASIO_TEST_CASE(test_2_arg_mutable_buffer_write)
   BOOST_ASIO_TEST_CASE(test_2_arg_vector_buffers_write)
   BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_zero_buffers_write)
-  BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_const_buffers_1_write)
-  BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_mutable_buffers_1_write)
+  BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_const_buffer_write)
+  BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_mutable_buffer_write)
   BOOST_ASIO_TEST_CASE(test_3_arg_nothrow_vector_buffers_write)
-  BOOST_ASIO_TEST_CASE(test_3_arg_const_buffers_1_write)
-  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffers_1_write)
+  BOOST_ASIO_TEST_CASE(test_3_arg_const_buffer_write)
+  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffer_write)
   BOOST_ASIO_TEST_CASE(test_3_arg_vector_buffers_write)
-  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffers_1_write)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_write)
+  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffer_write)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_write)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_write)
-  BOOST_ASIO_TEST_CASE(test_3_arg_const_buffers_1_async_write)
-  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffers_1_async_write)
+  BOOST_ASIO_TEST_CASE(test_3_arg_const_buffer_async_write)
+  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffer_async_write)
   BOOST_ASIO_TEST_CASE(test_3_arg_boost_array_buffers_async_write)
   BOOST_ASIO_TEST_CASE(test_3_arg_std_array_buffers_async_write)
   BOOST_ASIO_TEST_CASE(test_3_arg_vector_buffers_async_write)
   BOOST_ASIO_TEST_CASE(test_3_arg_streambuf_async_write)
-  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffers_1_async_write)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_async_write)
+  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffer_async_write)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_async_write)
   BOOST_ASIO_TEST_CASE(test_4_arg_boost_array_buffers_async_write)
   BOOST_ASIO_TEST_CASE(test_4_arg_std_array_buffers_async_write)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_async_write)
diff --git a/test/write_at.cpp b/test/write_at.cpp
index 57fa636f2c..ef96f1e994 100644
--- a/test/write_at.cpp
+++ b/test/write_at.cpp
@@ -18,7 +18,8 @@
 
 #include <cstring>
 #include "archetypes/async_result.hpp"
-#include <boost/asio/io_service.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/post.hpp>
 #include <boost/asio/streambuf.hpp>
 #include "unit_test.hpp"
 
@@ -41,19 +42,19 @@ using namespace std; // For memcmp, memcpy and memset.
 class test_random_access_device
 {
 public:
-  typedef boost::asio::io_service io_service_type;
+  typedef boost::asio::io_context::executor_type executor_type;
 
-  test_random_access_device(boost::asio::io_service& io_service)
-    : io_service_(io_service),
+  test_random_access_device(boost::asio::io_context& io_context)
+    : io_context_(io_context),
       length_(max_length),
       next_write_length_(max_length)
   {
     memset(data_, 0, max_length);
   }
 
-  io_service_type& get_io_service()
+  executor_type get_executor() BOOST_ASIO_NOEXCEPT
   {
-    return io_service_;
+    return io_context_.get_executor();
   }
 
   void reset()
@@ -67,15 +68,14 @@ class test_random_access_device
     next_write_length_ = length;
   }
 
-  template <typename Const_Buffers>
+  template <typename Iterator>
   bool check_buffers(boost::asio::uint64_t offset,
-      const Const_Buffers& buffers, size_t length)
+      Iterator begin, Iterator end, size_t length)
   {
     if (offset + length > max_length)
       return false;
 
-    typename Const_Buffers::const_iterator iter = buffers.begin();
-    typename Const_Buffers::const_iterator end = buffers.end();
+    Iterator iter = begin;
     size_t checked_length = 0;
     for (; iter != end && checked_length < length; ++iter)
     {
@@ -83,7 +83,7 @@ class test_random_access_device
       if (buffer_length > length - checked_length)
         buffer_length = length - checked_length;
       if (memcmp(data_ + offset + checked_length,
-            boost::asio::buffer_cast<const void*>(*iter), buffer_length) != 0)
+            iter->data(), buffer_length) != 0)
         return false;
       checked_length += buffer_length;
     }
@@ -91,6 +91,14 @@ class test_random_access_device
     return true;
   }
 
+  template <typename Const_Buffers>
+  bool check_buffers(boost::asio::uint64_t offset,
+      const Const_Buffers& buffers, size_t length)
+  {
+    return check_buffers(offset, boost::asio::buffer_sequence_begin(buffers),
+        boost::asio::buffer_sequence_end(buffers), length);
+  }
+
   template <typename Const_Buffers>
   size_t write_some_at(boost::asio::uint64_t offset,
       const Const_Buffers& buffers)
@@ -113,12 +121,14 @@ class test_random_access_device
       const Const_Buffers& buffers, Handler handler)
   {
     size_t bytes_transferred = write_some_at(offset, buffers);
-    io_service_.post(boost::asio::detail::bind_handler(
-          handler, boost::system::error_code(), bytes_transferred));
+    boost::asio::post(get_executor(),
+        boost::asio::detail::bind_handler(
+          BOOST_ASIO_MOVE_CAST(Handler)(handler),
+          boost::system::error_code(), bytes_transferred));
   }
 
 private:
-  io_service_type& io_service_;
+  boost::asio::io_context& io_context_;
   enum { max_length = 8192 };
   char data_[max_length];
   size_t length_;
@@ -130,11 +140,11 @@ static const char write_data[]
 static char mutable_write_data[]
   = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 
-void test_3_arg_const_buffers_1_write_at()
+void test_3_arg_const_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -172,11 +182,11 @@ void test_3_arg_const_buffers_1_write_at()
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 }
 
-void test_3_arg_mutable_buffers_1_write_at()
+void test_3_arg_mutable_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -216,8 +226,8 @@ void test_3_arg_mutable_buffers_1_write_at()
 
 void test_3_arg_vector_buffers_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
   buffers.push_back(boost::asio::buffer(write_data) + 32);
@@ -257,11 +267,11 @@ void test_3_arg_vector_buffers_write_at()
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 }
 
-void test_4_arg_nothrow_const_buffers_1_write_at()
+void test_4_arg_nothrow_const_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -306,11 +316,11 @@ void test_4_arg_nothrow_const_buffers_1_write_at()
   BOOST_ASIO_CHECK(!error);
 }
 
-void test_4_arg_nothrow_mutable_buffers_1_write_at()
+void test_4_arg_nothrow_mutable_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -357,8 +367,8 @@ void test_4_arg_nothrow_mutable_buffers_1_write_at()
 
 void test_4_arg_nothrow_vector_buffers_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
   buffers.push_back(boost::asio::buffer(write_data) + 32);
@@ -417,11 +427,11 @@ size_t short_transfer(const boost::system::error_code& ec,
   return !!ec ? 0 : 3;
 }
 
-void test_4_arg_const_buffers_1_write_at()
+void test_4_arg_const_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -779,11 +789,11 @@ void test_4_arg_const_buffers_1_write_at()
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 }
 
-void test_4_arg_mutable_buffers_1_write_at()
+void test_4_arg_mutable_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -1143,8 +1153,8 @@ void test_4_arg_mutable_buffers_1_write_at()
 
 void test_4_arg_vector_buffers_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
   buffers.push_back(boost::asio::buffer(write_data) + 32);
@@ -1504,11 +1514,11 @@ void test_4_arg_vector_buffers_write_at()
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 }
 
-void test_5_arg_const_buffers_1_write_at()
+void test_5_arg_const_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -1975,11 +1985,11 @@ void test_5_arg_const_buffers_1_write_at()
   BOOST_ASIO_CHECK(!error);
 }
 
-void test_5_arg_mutable_buffers_1_write_at()
+void test_5_arg_mutable_buffer_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -2448,8 +2458,8 @@ void test_5_arg_mutable_buffers_1_write_at()
 
 void test_5_arg_vector_buffers_write_at()
 {
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
   buffers.push_back(boost::asio::buffer(write_data) + 32);
@@ -2926,7 +2936,7 @@ void async_write_handler(const boost::system::error_code& e,
   BOOST_ASIO_CHECK(bytes_transferred == expected_bytes_transferred);
 }
 
-void test_4_arg_const_buffers_1_async_write_at()
+void test_4_arg_const_buffer_async_write_at()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -2936,9 +2946,9 @@ void test_4_arg_const_buffers_1_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -2946,8 +2956,8 @@ void test_4_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -2956,8 +2966,8 @@ void test_4_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -2967,8 +2977,8 @@ void test_4_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -2978,8 +2988,8 @@ void test_4_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -2989,8 +2999,8 @@ void test_4_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3000,8 +3010,8 @@ void test_4_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3011,8 +3021,8 @@ void test_4_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3020,12 +3030,12 @@ void test_4_arg_const_buffers_1_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
-void test_4_arg_mutable_buffers_1_async_write_at()
+void test_4_arg_mutable_buffer_async_write_at()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -3035,9 +3045,9 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -3045,8 +3055,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -3055,8 +3065,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -3066,8 +3076,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -3077,8 +3087,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -3088,8 +3098,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -3099,8 +3109,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -3110,8 +3120,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -3119,8 +3129,8 @@ void test_4_arg_mutable_buffers_1_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
@@ -3135,8 +3145,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -3146,8 +3156,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3156,8 +3166,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3167,8 +3177,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3178,8 +3188,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3189,8 +3199,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3200,8 +3210,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3211,8 +3221,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3220,8 +3230,8 @@ void test_4_arg_boost_array_buffers_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -3237,8 +3247,8 @@ void test_4_arg_std_array_buffers_async_write_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -3248,8 +3258,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3258,8 +3268,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3269,8 +3279,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3280,8 +3290,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3291,8 +3301,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3302,8 +3312,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3313,8 +3323,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3322,8 +3332,8 @@ void test_4_arg_std_array_buffers_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -3338,8 +3348,8 @@ void test_4_arg_vector_buffers_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
   buffers.push_back(boost::asio::buffer(write_data) + 32);
@@ -3349,8 +3359,8 @@ void test_4_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3359,8 +3369,8 @@ void test_4_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3370,8 +3380,8 @@ void test_4_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3381,8 +3391,8 @@ void test_4_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3392,8 +3402,8 @@ void test_4_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3403,8 +3413,8 @@ void test_4_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3414,8 +3424,8 @@ void test_4_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3423,8 +3433,8 @@ void test_4_arg_vector_buffers_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
@@ -3438,10 +3448,10 @@ void test_4_arg_streambuf_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb;
-  boost::asio::const_buffers_1 buffers
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -3451,8 +3461,8 @@ void test_4_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3463,8 +3473,8 @@ void test_4_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3476,8 +3486,8 @@ void test_4_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3489,8 +3499,8 @@ void test_4_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3502,8 +3512,8 @@ void test_4_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3515,8 +3525,8 @@ void test_4_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3528,8 +3538,8 @@ void test_4_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3539,12 +3549,12 @@ void test_4_arg_streambuf_async_write_at()
   int i = boost::asio::async_write_at(s, 0, sb,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
-void test_5_arg_const_buffers_1_async_write_at()
+void test_5_arg_const_buffer_async_write_at()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -3554,9 +3564,9 @@ void test_5_arg_const_buffers_1_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::const_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -3565,8 +3575,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3576,8 +3586,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3588,8 +3598,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3600,8 +3610,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3612,8 +3622,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3624,8 +3634,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3635,8 +3645,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3646,8 +3656,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3658,8 +3668,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -3670,8 +3680,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -3682,8 +3692,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -3694,8 +3704,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -3705,8 +3715,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3716,8 +3726,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3728,8 +3738,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -3740,8 +3750,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -3752,8 +3762,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -3764,8 +3774,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -3775,8 +3785,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -3786,8 +3796,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -3798,8 +3808,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -3810,8 +3820,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -3822,8 +3832,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -3834,8 +3844,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -3845,8 +3855,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -3856,8 +3866,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -3868,8 +3878,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -3880,8 +3890,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -3892,8 +3902,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -3904,8 +3914,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -3915,8 +3925,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -3926,8 +3936,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -3938,8 +3948,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -3950,8 +3960,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -3962,8 +3972,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -3974,8 +3984,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -3985,8 +3995,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -3996,8 +4006,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4008,8 +4018,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4020,8 +4030,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4032,8 +4042,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4044,8 +4054,8 @@ void test_5_arg_const_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4054,8 +4064,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4064,8 +4074,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4075,8 +4085,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4086,8 +4096,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4097,8 +4107,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4108,8 +4118,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4118,8 +4128,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4128,8 +4138,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4139,8 +4149,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4150,8 +4160,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4161,8 +4171,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4172,8 +4182,8 @@ void test_5_arg_const_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4181,12 +4191,12 @@ void test_5_arg_const_buffers_1_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
-void test_5_arg_mutable_buffers_1_async_write_at()
+void test_5_arg_mutable_buffer_async_write_at()
 {
 #if defined(BOOST_ASIO_HAS_BOOST_BIND)
   namespace bindns = boost;
@@ -4196,9 +4206,9 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
-  boost::asio::mutable_buffers_1 buffers
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
+  boost::asio::mutable_buffer buffers
     = boost::asio::buffer(mutable_write_data, sizeof(mutable_write_data));
 
   s.reset();
@@ -4207,8 +4217,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4218,8 +4228,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4230,8 +4240,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4242,8 +4252,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4254,8 +4264,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4266,8 +4276,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4277,8 +4287,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4288,8 +4298,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4300,8 +4310,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4312,8 +4322,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4324,8 +4334,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4336,8 +4346,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4347,8 +4357,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4358,8 +4368,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4370,8 +4380,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4382,8 +4392,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4394,8 +4404,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4406,8 +4416,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4417,8 +4427,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4428,8 +4438,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4440,8 +4450,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4452,8 +4462,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4464,8 +4474,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -4476,8 +4486,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -4487,8 +4497,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4498,8 +4508,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4510,8 +4520,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4522,8 +4532,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4534,8 +4544,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4546,8 +4556,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4557,8 +4567,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4568,8 +4578,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4580,8 +4590,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4592,8 +4602,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4604,8 +4614,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4616,8 +4626,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4627,8 +4637,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4638,8 +4648,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4650,8 +4660,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4662,8 +4672,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4674,8 +4684,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -4686,8 +4696,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -4696,8 +4706,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4706,8 +4716,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4717,8 +4727,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4728,8 +4738,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4739,8 +4749,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4750,8 +4760,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4760,8 +4770,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4770,8 +4780,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4781,8 +4791,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4792,8 +4802,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4803,8 +4813,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(mutable_write_data)));
 
@@ -4814,8 +4824,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(mutable_write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(mutable_write_data)));
 
@@ -4823,8 +4833,8 @@ void test_5_arg_mutable_buffers_1_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
@@ -4839,8 +4849,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -4851,8 +4861,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4862,8 +4872,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4874,8 +4884,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4886,8 +4896,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4898,8 +4908,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4910,8 +4920,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4921,8 +4931,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -4932,8 +4942,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -4944,8 +4954,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -4956,8 +4966,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -4968,8 +4978,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -4980,8 +4990,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -4991,8 +5001,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5002,8 +5012,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5014,8 +5024,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5026,8 +5036,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5038,8 +5048,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5050,8 +5060,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5061,8 +5071,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5072,8 +5082,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5084,8 +5094,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5096,8 +5106,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5108,8 +5118,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -5120,8 +5130,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -5131,8 +5141,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5142,8 +5152,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5154,8 +5164,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5166,8 +5176,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5178,8 +5188,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5190,8 +5200,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5201,8 +5211,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5212,8 +5222,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5224,8 +5234,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5236,8 +5246,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5248,8 +5258,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5260,8 +5270,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5271,8 +5281,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5282,8 +5292,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5294,8 +5304,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5306,8 +5316,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5318,8 +5328,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5330,8 +5340,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5340,8 +5350,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5350,8 +5360,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5361,8 +5371,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5372,8 +5382,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5383,8 +5393,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5394,8 +5404,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5404,8 +5414,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5414,8 +5424,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5425,8 +5435,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5436,8 +5446,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5447,8 +5457,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5458,8 +5468,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5467,8 +5477,8 @@ void test_5_arg_boost_array_buffers_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 }
@@ -5484,8 +5494,8 @@ void test_5_arg_std_array_buffers_async_write_at()
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::array<boost::asio::const_buffer, 2> buffers = { {
     boost::asio::buffer(write_data, 32),
     boost::asio::buffer(write_data) + 32 } };
@@ -5496,8 +5506,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5507,8 +5517,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5519,8 +5529,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5531,8 +5541,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5543,8 +5553,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5555,8 +5565,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5566,8 +5576,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5577,8 +5587,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5589,8 +5599,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5601,8 +5611,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5613,8 +5623,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5625,8 +5635,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5636,8 +5646,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5647,8 +5657,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5659,8 +5669,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5671,8 +5681,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5683,8 +5693,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5695,8 +5705,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5706,8 +5716,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5717,8 +5727,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -5729,8 +5739,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5741,8 +5751,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5753,8 +5763,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -5765,8 +5775,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -5776,8 +5786,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5787,8 +5797,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5799,8 +5809,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5811,8 +5821,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5823,8 +5833,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -5835,8 +5845,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -5846,8 +5856,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5857,8 +5867,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5869,8 +5879,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5881,8 +5891,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5893,8 +5903,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -5905,8 +5915,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -5916,8 +5926,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5927,8 +5937,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5939,8 +5949,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5951,8 +5961,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5963,8 +5973,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -5975,8 +5985,8 @@ void test_5_arg_std_array_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -5985,8 +5995,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -5995,8 +6005,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6006,8 +6016,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6017,8 +6027,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6028,8 +6038,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6039,8 +6049,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6049,8 +6059,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6059,8 +6069,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6070,8 +6080,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6081,8 +6091,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6092,8 +6102,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6103,8 +6113,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6112,8 +6122,8 @@ void test_5_arg_std_array_buffers_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
 }
@@ -6128,8 +6138,8 @@ void test_5_arg_vector_buffers_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   std::vector<boost::asio::const_buffer> buffers;
   buffers.push_back(boost::asio::buffer(write_data, 32));
   buffers.push_back(boost::asio::buffer(write_data) + 32);
@@ -6140,8 +6150,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6151,8 +6161,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6163,8 +6173,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6175,8 +6185,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6187,8 +6197,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6199,8 +6209,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6210,8 +6220,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6221,8 +6231,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6233,8 +6243,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6245,8 +6255,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6257,8 +6267,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6269,8 +6279,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6280,8 +6290,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6291,8 +6301,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6303,8 +6313,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6315,8 +6325,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6327,8 +6337,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6339,8 +6349,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6350,8 +6360,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6361,8 +6371,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6373,8 +6383,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6385,8 +6395,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6397,8 +6407,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -6409,8 +6419,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -6420,8 +6430,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6431,8 +6441,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6443,8 +6453,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6455,8 +6465,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6467,8 +6477,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6479,8 +6489,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6490,8 +6500,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6501,8 +6511,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6513,8 +6523,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6525,8 +6535,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6537,8 +6547,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6549,8 +6559,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6560,8 +6570,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6571,8 +6581,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6583,8 +6593,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6595,8 +6605,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6607,8 +6617,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -6619,8 +6629,8 @@ void test_5_arg_vector_buffers_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -6629,8 +6639,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6639,8 +6649,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6650,8 +6660,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6661,8 +6671,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6672,8 +6682,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6683,8 +6693,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6693,8 +6703,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6703,8 +6713,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6714,8 +6724,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6725,8 +6735,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6736,8 +6746,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 0, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6747,8 +6757,8 @@ void test_5_arg_vector_buffers_async_write_at()
   boost::asio::async_write_at(s, 1234, buffers, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6756,8 +6766,8 @@ void test_5_arg_vector_buffers_async_write_at()
   int i = boost::asio::async_write_at(s, 0, buffers, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
@@ -6771,10 +6781,10 @@ void test_5_arg_streambuf_async_write_at()
   using std::placeholders::_2;
 #endif // defined(BOOST_ASIO_HAS_BOOST_BIND)
 
-  boost::asio::io_service ios;
-  test_random_access_device s(ios);
+  boost::asio::io_context ioc;
+  test_random_access_device s(ioc);
   boost::asio::streambuf sb;
-  boost::asio::const_buffers_1 buffers
+  boost::asio::const_buffer buffers
     = boost::asio::buffer(write_data, sizeof(write_data));
 
   s.reset();
@@ -6785,8 +6795,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6798,8 +6808,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6812,8 +6822,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6826,8 +6836,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6840,8 +6850,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6854,8 +6864,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_all(),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6867,8 +6877,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6880,8 +6890,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6894,8 +6904,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -6908,8 +6918,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -6922,8 +6932,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6936,8 +6946,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(1),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -6949,8 +6959,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -6962,8 +6972,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -6976,8 +6986,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -6990,8 +7000,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -7004,8 +7014,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -7018,8 +7028,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -7031,8 +7041,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -7044,8 +7054,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -7058,8 +7068,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -7072,8 +7082,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -7086,8 +7096,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 50));
 
@@ -7100,8 +7110,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_at_least(42),
       bindns::bind(async_write_handler,
         _1, _2, 50, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 50));
 
@@ -7113,8 +7123,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -7126,8 +7136,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -7140,8 +7150,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -7154,8 +7164,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -7168,8 +7178,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 1));
 
@@ -7182,8 +7192,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(1),
       bindns::bind(async_write_handler,
         _1, _2, 1, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 1));
 
@@ -7195,8 +7205,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -7208,8 +7218,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -7222,8 +7232,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -7236,8 +7246,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -7250,8 +7260,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 10));
 
@@ -7264,8 +7274,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(10),
       bindns::bind(async_write_handler,
         _1, _2, 10, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 10));
 
@@ -7277,8 +7287,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -7290,8 +7300,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -7304,8 +7314,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -7318,8 +7328,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -7332,8 +7342,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, 42));
 
@@ -7346,8 +7356,8 @@ void test_5_arg_streambuf_async_write_at()
       boost::asio::transfer_exactly(42),
       bindns::bind(async_write_handler,
         _1, _2, 42, &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, 42));
 
@@ -7358,8 +7368,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -7370,8 +7380,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -7383,8 +7393,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -7396,8 +7406,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -7409,8 +7419,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -7422,8 +7432,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb, old_style_transfer_all,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -7434,8 +7444,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -7446,8 +7456,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -7459,8 +7469,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -7472,8 +7482,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -7485,8 +7495,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 0, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 
@@ -7498,8 +7508,8 @@ void test_5_arg_streambuf_async_write_at()
   boost::asio::async_write_at(s, 1234, sb, short_transfer,
       bindns::bind(async_write_handler,
         _1, _2, sizeof(write_data), &called));
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(called);
   BOOST_ASIO_CHECK(s.check_buffers(1234, buffers, sizeof(write_data)));
 
@@ -7509,34 +7519,34 @@ void test_5_arg_streambuf_async_write_at()
   int i = boost::asio::async_write_at(s, 0, sb, short_transfer,
       archetypes::lazy_handler());
   BOOST_ASIO_CHECK(i == 42);
-  ios.reset();
-  ios.run();
+  ioc.restart();
+  ioc.run();
   BOOST_ASIO_CHECK(s.check_buffers(0, buffers, sizeof(write_data)));
 }
 
 BOOST_ASIO_TEST_SUITE
 (
   "write_at",
-  BOOST_ASIO_TEST_CASE(test_3_arg_const_buffers_1_write_at)
-  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffers_1_write_at)
+  BOOST_ASIO_TEST_CASE(test_3_arg_const_buffer_write_at)
+  BOOST_ASIO_TEST_CASE(test_3_arg_mutable_buffer_write_at)
   BOOST_ASIO_TEST_CASE(test_3_arg_vector_buffers_write_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_const_buffers_1_write_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_mutable_buffers_1_write_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_const_buffer_write_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_mutable_buffer_write_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_nothrow_vector_buffers_write_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffers_1_write_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_write_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffer_write_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_write_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_write_at)
-  BOOST_ASIO_TEST_CASE(test_5_arg_const_buffers_1_write_at)
-  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffers_1_write_at)
+  BOOST_ASIO_TEST_CASE(test_5_arg_const_buffer_write_at)
+  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffer_write_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_vector_buffers_write_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffers_1_async_write_at)
-  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffers_1_async_write_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_const_buffer_async_write_at)
+  BOOST_ASIO_TEST_CASE(test_4_arg_mutable_buffer_async_write_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_boost_array_buffers_async_write_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_std_array_buffers_async_write_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_vector_buffers_async_write_at)
   BOOST_ASIO_TEST_CASE(test_4_arg_streambuf_async_write_at)
-  BOOST_ASIO_TEST_CASE(test_5_arg_const_buffers_1_async_write_at)
-  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffers_1_async_write_at)
+  BOOST_ASIO_TEST_CASE(test_5_arg_const_buffer_async_write_at)
+  BOOST_ASIO_TEST_CASE(test_5_arg_mutable_buffer_async_write_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_boost_array_buffers_async_write_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_std_array_buffers_async_write_at)
   BOOST_ASIO_TEST_CASE(test_5_arg_vector_buffers_async_write_at)