Not being able to trace through your code while doing a Mono port of an ASP.NET application can seriously hamper productivity. Until the Mono debugger is finally ready for prime time, we'll have to debug the old-school way.
One easy way of getting debug output from a Mono application is to simply use Console.WriteLine. If you're running your ASP.NET application through XSP2, the console output will be visible from the terminal that XSP was run in.
.NET supports using TraceListeners for capturing System.Configuration.Debug output. There is a handy ConsoleTraceListener that will convert all calls to Debug.WriteLine to console calls. This would be fantastic for Mono usage, but alas,
Mono does not appear to support TraceListeners at all! My tests have shown that the overridden abstract methods in a TraceLister descendant are never called.
UPDATE: Seems my assumptions about TraceListeners not working in Mono was a bit premature, but not all that far off the mark.
As it turns out, TraceListeners do work, but only when you're running an application that has debugging enabled. This is the expected behaviour, and .NET follows the same guidelines.
However, when running a "Web Site" project (one that hasn't been pre-compiled), Mono still seems to have some issues. If you set the <compilation debug="true"> flag in the Web.config file, the application should be build with debug symbols and all debug output should function as expected. I've confirmed this to work on .NET, but am unable to get this working with XSP2 (Windows or Linux). The debug output does work however if you use a pre-compiled web site (i.e. ASP.NET Web Application in Visual Studio) compiled under the Debug configuration.
The Mono ASP.NET page suggests doing the following:
$ MONO_OPTIONS=--debug xsp2
Listening on port: 8080 (non-secure)
Listening on address: 0.0.0.0
Root directory: /tmp/us
Hit Return to stop the server.
This hasn't worked for me however. If anyone knows what I'm doing wrong here, please drop me a line and let me know!