Added NLog 4.6 is live post

_posts/2019-02-30-nlog-4-6-is-live.md

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+---
+layout: post
+title: NLog 4.6 is live!
+---
+
+NLog 4.6 contains lots of new features and performance improvements.
+
+## Main features
+
+### DatabaseTarget supports parameter types
+It is now possible to configure the type for the DatabaseTarget parameters.
+Instead of always sending string-value then one can write the actual value-type.
+
+```xml
+<target name="db" xsi:type="Database" connectionstring="..." >
+  <commandtext>INSERT INTO FooBar VALUES(@ts, @lvl, @msg)</commandtext>
+  <parameter name="@ts" layout="${date}" dbType="SqlDbType.DateTime2" />
+  <parameter name="@lvl" layout="${level}" dbType="DbType.Int32" />
+  <parameter name="@msg" layout="${message}" dbType="SqlDbType.VarChar" size="-1" parameterType="String" />
+</target>
+```
+
+When using a non-string DbType then it will attempt to convert the raw value directly to the expected type.
+When using special DbType like `SqlDbType.SmallInt` then one can specify `parameterType="Int16"` to help.
+
+This will skip the overhead of first rendering to string, and parsing the string into the expected type.
+
+If wanting to use non-string DbType but want the value parsed from string, then one can do this: `${date:format=yyyy-MM-dd:norawvalue=true}` or specify `parameterType="String"`.
+
+### NetworkTarget supports SSL & TLS
+NetworkTarget can now perform SSL/TLS handshake for the TCP-protocol:
+
+```xml
+<target name="net" type="network" address="tcp://127.0.0.1" sslProtocols="Tls12" />
+```
+
+NetworkTarget has also received a new TCP option for activating KeepAliveTime. **keepAliveTimeSeconds="30"** can be used to keep TCP connection going when no traffic (with very little overhead).
+
+### New XmlLayout
+XmlLayout is now available for creating XML files.
+
+Just like with JsonLayout then XmlLayout supports object reflection, so it can be used in combination with structured logging.
+
+```xml
+      <layout xsi:type="XmlLayout" includeAllProperties="True" elementName='logevent'>
+              <attribute name="time" layout="${longdate}" />
+              <attribute name="level" layout="${level:upperCase=true}"/>
+              <element name="message" layout="${message}" />
+      </layout>
+```
+
+Will write:
+
+```xml
+<logevent time="2010-01-01 12:34:56.0000" level="ERROR">
+   <message>hello, world</message>
+</logevent>
+```
+
+This can also be used together with the DatabaseTarget for writing XML to a database:
+
+```xml
+<parameter name="@props" dbType="SqlDbType.Xml">
+   <layout type="xmllayout" includeAllProperties="true" />
+</parameter>
+```
+
+
+### Variables in level attributes
+In the XML configuration you could now variables in the level attributes (minlevel, maxlevel, level and levels),
+
+ e.g.
+
+```xml
+<nlog>
+   <variable name='myLevel' value='debug'/>
+    <rules>
+      <logger minLevel='${myLevel}'/>
+    </rules>
+</nlog>
+```
+
+Note: for performance reasons, ${var:myLevel} or other layout renderers won't work.
+
+### Added default action for filtering
+
+Currently the default action for filtering - when not matching any rule - is "neutral". 
+
+This is a bit tricky. This could be now configured with the attribute defaultAction. Possible values: Neutral, Ignore,  Log,  LogFinal, IgnoreFinal
+
+```xml
+<rules>
+    <logger name='*' level='Warn' writeTo='myTarget'>
+        <filters defaultAction='Ignore'>
+            <when condition=""starts-with(message, 't')"" action='Log' />
+        </filters>
+    </logger>
+</rules>
+```
+
+In NLog 5 the default will be probably changed to "ignore"
+
+### Substring, left and right
+
+New layout renders has been added:
+
+```
+${substring:${level}:start=2:length=2}    // from index 2, length 2
+${substring:${level}:start=-2:length=2}   // from end -2, length 2
+${left:${level}:length=2}    // from start, length 2
+${right:${level}:length=2}   // from end, length 2
+```
+
+### Name filter: support for multiple wildcards and in any position
+In NLog 4.5 and before, the wildcards in the name filter of the <rule> element was limited. 
+
+- `?` was not supported
+- Only one `*` was allowed the name filter. 
+
+With a new implementation, those restrictions are now gone and `?` wildcard has been added.
+
+- `*` - matches 0 or more characters
+- `?` - matches exactly 1 character
+
+Examples
+
+```xml
+  <logger name="*.Library.*" minlevel="Warn" writeTo="f3" />
+  <logger name="*TcpTestServer[*].Connection[??].*" writeTo="logconsole" />
+```
+
+
+### InternalLogFile variables
+
+The internalLogFile attribute is for stability limited in features, no layout renderers where allowed. 
+
+In NLog 4.6 we added support for: ${currentdir}, ${basedir} & ${tempdir}, and for environment variables, like `%myPath%` 
+
+example:
+
+```xml
+<nlog internalLogFile="${basedir}\log.txt" internalLogLevel="Trace">
+   <targets>
+      <!-- target configuration here -->
+   </targets>
+   <rules>
+      <!-- log routing rules -->
+   </rules>
+</nlog>
+```
+
+
+### AsyncWrapper uses ConcurrentQueue
+ConcurrentQueue has been optimized with .NET Standard 2.0, so it provides high performance and little allocation.
+
+NLog AsyncWrapper will now automatically make use of ConcurrentQueue when running on .NET Core 2 platform.
+This will greatly reduce the congestion overhead of having multiple threads writing to the same AsyncWrapper.
+
+### AsyncWrapper with faster timer
+AsyncWrapper no longer schedules a timer every 50 ms even if nothing to write. Instead it will schedule a single
+timer on first write and the timer will trigger after 1 ms.
+
+This allows the AsyncWrapper to handle high loads out of the box, but will also make it more aggressive on the
+target it is wrapping. Instead of writing 40000 msgs/sec then it will handle 400000 msgs/sec.
+
+### ColoredConsoleTarget supports Ansi output
+Console coloring now also works on VS Code or other console terminal using ANSI color escape sequences.
+
+```xml
+<target name="console" xsi:type="ColoredConsole" enableAnsiOutput="true" />
+```
+
+### AppSetting without NLog.Extended
+NLog.Extended was needed when wanting to use `${appsetting}` on .NET Framework. But it also had
+dependencies on System.Messaging (MSMQ). Since NLog already dependends on System.Configuration
+then it didn't make sense also to need NLog.Extended for reading app.config / web.config.
+
+### NLog configuration inside appsettings.json
+NLog LoggingConfiguration have always been highly configurable through XML. It is now also possible
+to configure NLog to parse the configuration from other sources.
+
+NLog.Extension.Logging is now able to load NLog LoggingConfiguration from Microsoft Extension ConfigurationSection.
+
+This can be used for loading NLog-configuration from appsettings.json:
+
+```c#
+var config = new ConfigurationBuilder()
+  .SetBasePath(System.IO.Directory.GetCurrentDirectory())
+  .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
+  .Build();
+
+var nlogSection = config.GetSection("NLog");
+LogManager.Configuration = new NLog.Extensions.Logging.ExtensionLoggingConfiguration(nlogSection);
+```
+
+```json
+{
+    "NLog": {
+        "internalLogLevel": "Info",
+        "internalLogFile": "c:/temp/console-example-internal.log",
+        "throwConfigExceptions": "True",
+        "targets": {
+            "console": {
+                "type": "Console",
+                "layout": "${longdate}|${level:uppercase=true}|${logger}|${message}${exception:format=tostring}"
+            }
+        },
+        "rules": [
+            {
+                "logger": "*",
+                "minLevel": "Trace",
+                "writeTo": "File,Console"
+            }
+        ]
+    }
+}
+```
+
+### LibLog Breaking change
+[damianh/LibLog#181](https://github.com/damianh/LibLog/pull/181) - Sub-components using LibLog ver. 5.0.3 (or newer)
+will now use MDLC + NDLC (Instead of MDC + NDC) when detecting application is using NLog ver. 4.6.
+- Make sure to update NLog.config to match this change.
+- Make sure that all sub-components have upgraded to LibLog ver. 5.0.3 (or newer) if they make use of `OpenNestedContext` or `OpenMappedContext`.
+
+## Many other improvements
+
+For a full list of all the enhancements and performance improvements: [NLog 4.6 Release Notes](https://github.com/NLog/NLog/blob/master/CHANGELOG.md)