WebAPI 2.2 and Trace.axd - asp.net-web-api

Question

I'm using WebApi 2.2 and have installed the WebApi 2.2 Tracing package.
In my WebApiConfig.Register method, I have added this line:
config.EnableSystemDiagnosticsTracing();
I'd like to write out some information to trace.axd in my action methods, like what I used to do with ASP.NET webform.
Something like:
[Route("getCurrentUser")]
[HttpPost]
public IHttpActionResult GetCurrentUser()
{
Trace.WriteLine("GetCurrentUser"); // doesn't work
Configuration.Services.GetTraceWriter().Warn(
Request, "AccountController", "GetCurrentUser"); // doesn't work either
}
However I'm not seeing anything in trace.axd.
I do see the info logged in visual studio though, when I debug it, but it's writing out too much information which I don't need.
What I really want is to only see the trace information I specifically write in my action methods.
Thanks!!

Answer 1

When you enable that, it creates a new instance of SystemDiagnosticsTraceWriter class. The default TraceLevel is Info so your Warn should work.
By default, the SystemDiagnosticsTraceWriter writes traces to System.Diagnostics.Trace and they are written in the Output window of the Visual Studio. So you should register additional Trace Listeners.
You should configure it in your web config where to write the tracing logic to?
I'm guessing the Trace.axd is the ASP.NET Trace Viewer and works with ASP.NET Pages. not sure whether it can work with Web API.
But you can configure a different trace listener e.g. to Event Log or Console, or File or your custom trace writer:
<system.diagnostics>
<trace autoflush="false" indentsize="4">
<listeners>
<add name="eventLogListener"
type="System.Diagnostics.EventLogTraceListener"
initializeData="TraceListenerLog" />
<add name="logFileListener"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="E:\CompressedLogs\Service1-WebApi-TraceOutput.log" />
<remove name="Default" />
</listeners>
</trace>
</system.diagnostics>

Answer 2

Great question, I'm choosing an Web API tracing component and the first one that pops to mind is ASP.NET Tracing, as it is easy to enable/disable and secure. There's no need to install additional packages; the ASP.NET Trace can be used through System.Web.HttpContext.Current:
using System.Web;
...
catch(Exception e)
{
HttpContext.Current.Trace.Warn("MyWebAPI", string.Format("[ERROR] {0}", e));
}
Remember to enable trace in web.config:
<trace enabled="true" pageOutput="false" localOnly="true" requestLimit="200" />
I aways use pageOutput="false" localOnly="true" because I think it's the most secure trace configuration (other than being disabled ;-): there's no trace output on the pages, and the trace can be viewed only by a browser running on the server.
If you need to view the trace on production enviroments, remember to turn it off after you use it.