OpenWriteCompletedEventArgs Class

    public static void OpenResourceForPosting (string address)
    {
        WebClient client = new WebClient ();
        Uri uri = new Uri(address);

        // Specify that the OpenWriteCallback method gets called
        // when the writeable stream is available.
        client.OpenWriteCompleted += new OpenWriteCompletedEventHandler (OpenWriteCallback2);
        client.OpenWriteAsync (uri);
        // Applications can perform other tasks
        // while waiting for the upload to complete.
    }

    private static void OpenWriteCallback2 (Object sender, OpenWriteCompletedEventArgs e)
    {
        Stream body = null;
        StreamWriter s = null;

        try
        {
            body = (Stream)e.Result;
            s = new StreamWriter (body);
            s.AutoFlush = true;
            s.Write ("This is content data to be sent to the server.");
        }
        finally
        {
            if (s != null)
            {
                s.Close ();
            }

            if (body != null)
            {
                body.Close ();
            }
        }
    }