public class NotifyCallbackHelper
    {
      private string  callBackUrl = string.Empty;
      byte[] buffer = new byte[8290];
      private readonly static HttpListener listener = new HttpListener();

      public NotifyCallbackHelper(string callBackUrl)
      {
          this.callBackUrl = callBackUrl;
      }

      public void StartNotify()
      {
          listener.Prefixes.Add(callBackUrl);
          listener.Start();
          listener.BeginGetContext(NotifyCallback,listener);
      }

      public void NotifyCallback(IAsyncResult result)
      {
          try
          {
              HttpListener listener  =(HttpListener)result.AsyncState;
              HttpListenerContext context = listener.EndGetContext(result);
              ThreadPool.QueueUserWorkItem(new WaitCallback(ReadWrite),context);
              listener.BeginGetContext(NotifyCallback, listener);
          }
          catch(Exception ex)
          {

          }
      }

      public void ReadWrite(object o)
      {
          HttpListenerContext context = o as HttpListenerContext;
          Stream s = context.Request.InputStream;
          s.Read(buffer, 0, buffer.Length);
          context.Response.StatusCode = 200;
      }

      public void Close()
      {
          listener.Close();
      }
    }