Fix ExeUnit interaction in architecture-snapshot

arch-snapshot/arch.md

@@ -2247,40 +2247,19 @@ time.
   over the Internet –
   [ya-runtime-http-auth](https://github.com/golemfactory/ya-runtime-http-auth).
 
-#### Interaction between Golem Node and ExeUnits
-ExeUnits are controlled by the Golem Node using GSB, the same message-passing
-protocol that is used for internal implementation of the Node as well as
-inter-node communication.
-
-In case of the Generic ExeUnits the GSB messages are split into two services:
-- Counters Service
-  - `GetCounters` returns the Usage Counters relevant for the pricing according
-    to the choosen payment model.
-  - `SetCounter` overrides the value of a specific counter.
-  - `Shutdown` informs the service of imminent shutdown.
-- Transfer Service
-  - `DeployImage` transfers the GVMI image and starts the underlying Runtime.*
-  - `TransferResource` transfers a resource (usually a file) between
-    the Provider and the Runtime.*
-  - `AddVolumes` creates additional points within Runtime filesystem writing
-    to which will allow files to be accessed via `TransferResource` by the
-    Requestor. That is, `TransferResource` cannot operate on arbitrary paths
-    when accessing Runtime data, but is instead limited to the *Volumes*
-    created by this GSB call.
-  - `AbortTransfers` cancels all ongoing transfers.
-  - `Shutdown` informs the service of imminent shutdown.
-
-*Note regarding transfers: The destination of a transfer must always implement
-a specific GSB-based interface, but the source can be either a symmetric GSB-API
-*or* an HTTP resource. For the details of the GSB Transfer APIs, see
-[gftp implementation](https://github.com/golemfactory/yagna/tree/master/core/gftp).
-
-Additionally, some GSB endpoints are exposed directly to the Requestor Agent,
-such as:
+#### Interaction between Requestor and ExeUnit
+ExeUnits expose 4 GSB endpoints to be directly called by the Provider:
 - `Exec`
+  - Executes the ExeScript on the ExeUnit, see [ExeUnit Commands](#exeunit-commands).
 - `GetExecBatchResults`
+  - Returns the results of the batch.
+- `StreamExecBatchResults`
+  - Streams the results of the batch as it progresses.
+- `GetRunningCommand`
+  - Returns the currently running command from the batch
 
-(Details below)
+#### Interaction between Provider and ExeUnit
+- Periodic reporting of Counters' values to the Provider via GSB
 
 #### ExeUnit Commands
 The Requestor Agent does not control the ExeUnit by GSB, but by using
@@ -2290,6 +2269,11 @@ to the `Exec` GSB message that is then sent directly to the ExeUnit.
 The specification of the command (so-called `ExeScriptCommand`) can be found
 in [ya-client OpenAPI Activity Specification](https://github.com/golemfactory/ya-client/blob/master/specs/activity-api.yaml).
 
+Note regarding `Transfer` command: The destination of a transfer must always
+implement a specific GSB-based interface, but the source can be either
+a symmetric GSB-API *or* an HTTP resource. For the details of the GSB Transfer
+APIs, see [gftp implementation](https://github.com/golemfactory/yagna/tree/master/core/gftp).
+
 ##### Batches
 Commands are to be sent in *Batches* which are considered done after each
 command has completed in order.