System.Net (HttpWebRequest) tracing without using files or app.config?

Question

I want to capture certain, but not all, HttpWebRequest traffic in my application for debugging purposes. It's a web service hosted by IIS.

I have read How to: Configure Network Tracing. This works great, but I don't want to direct the trace to a file, due to possible permission problems on the file system, data sensitivity, etc. I would like to capture directly to a something in-memory that I can subsequently inspect or encrypt and email. Preferably, this would not involve any changes to the app.config file.

I tried the following, but obviously I am missing a step to tie the TextWriterTraceListener into System.Net. How can I capture the System.Net traffic into my StringWriter?

StringWriter sw = new StringWriter();
TextWriterTraceListener myListener = new TextWriterTraceListener(sw);
Trace.Listeners.Add(myListener);
HttpWebRequest req = (HttpWebRequest) WebRequest.Create("http://www.microsoft.com");
HttpWebResponse resp = (HttpWebResponse) req.GetResponse();
Stream s = resp.GetResponseStream();

byte[] buf = new byte[4096];
while (s.Read(buf, 0, buf.Length) > 0) ;
s.Close();

myListener.Flush();
sw.Flush();

Edit: Specifically, I want to do the equivalent of this at runtime, except that I don't want output to go to network.log, I want it to go to a string buffer I've set up for this purpose.

<configuration>

<system.diagnostics>

<sources>
  <source name="System.Net.Sockets" tracemode="includehex">
    <listeners>
      <add name="System.Net.Sockets" type="System.Diagnostics.TextWriterTraceListener" initializeData="network.log" />
    </listeners>
  </source>
</sources>

<switches>
  <add name="System.Net.Sockets" value="Verbose"/>
</switches>

<trace autoflush="true" />
</system.diagnostics>
</configuration>

Answer 1

Well, for starters let me say say that all the settings that you can configure or modify in the App.Config you should also be able to configure or modify programmatically.

Second, in order to enable tracing in the System.Net namespace (which contains HttpWebRequest) you have to specify this in the App.config, or do the same in code. Then map listeners to each source. From what I can see looking at your code it seems you are missing the source mapping so I would look at the SourceFilter class.

Also, I would suggest getting the tracing to work using the App.config first and then trying to replicate the behavior in code. Here is a link that shows how to enable System.Net tracing using the config file.

Answer 2

You can create your own TraceListener implementation. The example(s) I have found online that configure things at run-time do not show working with the system trace sources. If you don't mind getting your hands dirty you could try using reflection to toggle the private static bool System.Net.Logging.s_LoggingEnabled (.NET 2).

Take the example in the following article and switch it from sending e-mails to publishing a static event that you can subscribe to when you're interested in receiving trace messages:

Extending System.Diagnostics

This does cause a performance hit since logging is enabled all the time (all or nothing as configured in the web.config). (See this article and comments explaining the importance of removing the default trace to improve performance.)