Multiplexing Log Output to Several Frameworks

This article shows how to send PostSharp logging output to two or more logging frameworks using MultiplexerBackend.

Using the multiplexer

The MultiplexerBackend is a LoggingBackend that sends logging events to two or more other logging backends ("child backends"). This way, you can log to multiple outputs or frameworks at the same time. For example, you could send output to console and Application Insights at the same time.

To set it up, create two or more logging backends in your initialization code, pass them as arguments to the constructor of the multiplexer, and then use the multiplexer as your backend, for example:

// Set up the first logging backend (console):
LoggingBackend backend1 = new ConsoleLoggingBackend();

// Set up the second logging backend:
Gibraltar.Agent.Log.StartSession();
LoggingBackend backend2 = new ApplicationInsightsBackend();

// Configure PostSharp Logging to use both backends:
LoggingServices.DefaultBackend = new MultiplexerBackend(backend1, backend2);

Configuring the backends

You can still configure options, such as verbosity, logging of details and backend-specific options. You should do this configuration on the child backends, not the multiplexer backend itself.

If you attempt to set the minimum verbosity for a role, namespace or type on the multiplexer itself, a NotSupportedException is thrown. Any other options you set on the multiplexer (for example, IncludeManualLoggingSourceLineInfo) have no effect. Set them on the child backends instead.

For example, you can configure one backend to receive all logging events and a second backend to receive only warnings like this:

// Set up the first logging backend (console):
LoggingBackend backend1 = new ConsoleLoggingBackend();
backend1.DefaultVerbosity.SetMinimalLevel(LogLevel.Trace);

// Set up the second logging backend:
Gibraltar.Agent.Log.StartSession();
LoggingBackend backend2 = new ApplicationInsightsBackend();
backend2.DefaultVerbosity.SetMinimalLevel(LogLevel.Warning);

// Configure PostSharp Logging to use both backends:
LoggingServices.DefaultBackend = new MultiplexerBackend(backend1, backend2);

Handling logging errors

If an exception occurs in logging, only the LoggingBackend responsible for the failure is disabled. The other backends in the multiplexer will continue to log events.

If you need a different behavior (for example, you need to disable all logging backends in that case, or conversely, you don't want any backends disabled), you can override this default exception handling behavior. See Handling Logging Exceptions for details.

See Also

Reference

MultiplexerBackend
Other Resources

Handling Logging Exceptions