Captures output from System Diagnostics Trace and redirects to NLog Targets.

• DisableFlush - Ignore flush operations from System.Diagnostics.Trace (Default = True)
• DefaultLogLevel - Use this default LogLevel for all LogEvents without any LogLevel.
• ForceLogLevel - Always use this LogLevel for all LogEvents (independent on the one provided).
• AutoLoggerName - Always capture StackTrace for each LogEvent and resolve Logger-name from callsite (Default = False)

Update app.config to redirect from the WCF ServiceModel-source to NLog Target output:

  <system.diagnostics>
    <sources>
      <source name="System.ServiceModel.MessageLogging" switchValue="All">
        <listeners>
          <add name="nlog" />
        </listeners>
      </source>
    </sources>
    <sharedListeners>
      <add name="nlog" type="NLog.NLogTraceListener, NLog"  />
    </sharedListeners>
  </system.diagnostics>

and

  <system.serviceModel>
    <diagnostics>
        <messageLogging logEntireMessage="true"
                        logMalformedMessages="true"
                        logMessagesAtServiceLevel="true"
                        logMessagesAtTransportLevel="true"
                        />
    </diagnostics>
  </system.serviceModel>

System.Diagnostics.Trace.Listeners.Clear();
System.Diagnostics.Trace.Listeners.Add(new NLog.NLogTraceListener { Name = "NLog" });
System.Diagnostics.Trace.WriteLine("Hello World");

NLogTraceListener is threadsafe and supports multithreading. To improve concurrency then ensure useGlobalLock is false (Default = true). See also LowLevelDesign.org - Case of deadlock

NLogTraceListener does not need help with flushing, since this is handled automatically by the NLog engine. To improve performance then ensure autoflush is false (Default = false).

  <system.diagnostics>
    <trace useGlobalLock="false" />
    <trace autoflush="false" />
  </system.diagnostics>

If having setup NLogTraceListener and at the same time using custom NLog Target that depends on System.Diagnostics.Trace for diagnostics tracing, then one can experience StackOverflowException. Since it is just like calling NLog Logger from NLog Target, which is also forbidden.

Possible solution is to setup filtering of the particular Trace-source, so it doesn't become a recursive loop.