Net capture of the HttpListener BeginGetContext method

Question

I am using HttpListener and using BeginGetContext to get my context object. I want to cleanly close my HttpListener, but if I try to do Close on the listener, I get an exception and this causes my program to exit.

using System; using System.Net; namespace Sandbox_Console { class Program { public static void Main() { if (!HttpListener.IsSupported) { Console.WriteLine("Windows XP SP2 or Server 2003 is required to use the HttpListener class."); return; } // Create a listener. HttpListener listener = new HttpListener(); listener.Prefixes.Add("http://vwdev.vw.local:8081/BitsTest/"); listener.Start(); Console.WriteLine("Listening..."); listener.BeginGetContext(Context, listener); Console.ReadLine(); listener.Close(); //Exception on this line, but not shown in Visual Studio Console.WriteLine("Stopped Listening..."); //This line is never reached. Console.ReadLine(); } static void Context(IAsyncResult result) { HttpListener listener = (HttpListener)result.AsyncState; HttpListenerContext context = listener.EndGetContext(result); context.Response.Close(); listener.BeginGetContext(Context, listener); } } } 

The program throws an exception in listener.Close() , however the error is never displayed in Visual Studio, the only note I get is the following on the Debug output screen:

The first random error occurred in System.dll such as "System.ObjectDisposedException" The program '[2568] Sandbox Console.vshost.exe: Managed (v4.0.30319)' exited with code 0 (0x0).

I managed to get real performance from Event Viewer windows

 Application: Sandbox Console.exe
 Framework Version: v4.0.30319
 Description: The process was terminated due to an unhandled exception.
 Exception Info: System.ObjectDisposedException
 Stack:
    at System.Net.HttpListener.EndGetContext (System.IAsyncResult)
    at Sandbox_Console.Program.Context (System.IAsyncResult)
    at System.Net.LazyAsyncResult.Complete (IntPtr)
    at System.Net.ListenerAsyncResult.WaitCallback (UInt32, UInt32, System.Threading.NativeOverlapped *)
    at System.Threading._IOCompletionCallback.PerformIOCompletionCallback (UInt32, UInt32, System.Threading.NativeOverlapped *)

What do I need to do so that I can close my HttpListener cleanly?

Answer 1

The context is called the last time you call Close, you must handle the exception of the object that can be thrown

 static void Context(IAsyncResult result) { HttpListener listener = (HttpListener)result.AsyncState; try { //If we are not listening this line throws a ObjectDisposedException. HttpListenerContext context = listener.EndGetContext(result); context.Response.Close(); listener.BeginGetContext(Context, listener); } catch (ObjectDisposedException) { //Intentionally not doing anything with the exception. } } 

Answer 2

You can add this line

 if (!listener.IsListening) { return; } HttpListenerContext context = listener.EndGetContext(ctx);