private void WaitForData(string sSocketName)
        {
            if (sSocketName.Equals("Level1"))
            {
                // make sure we have a callback created
                if (m_pfnLevel1Callback == null)
                {
                    m_pfnLevel1Callback = new AsyncCallback(OnReceive);
                }
                // send the notification to the socket.  It is very important that we dont call Begin Reveive more than once per call
                // to EndReceive.  As a result, we set a flag to ignore multiple calls.
                if (m_bLevel1NeedBeginReceive)
                {
                    m_bLevel1NeedBeginReceive = false;
                    // we pass in the sSocketName in the state parameter so that we can verify the socket data we receive is the data we are looking for
                    m_sockLevel1.BeginReceive(m_szLevel1SocketBuffer, 0, m_szLevel1SocketBuffer.Length, SocketFlags.None, m_pfnLevel1Callback, sSocketName);
                }
            }
        }
        /// <summary>
        /// OnReceive is our Callback that gets called by the .NET socket class when new data arrives on the socket
        /// </summary>
        /// <param name="asyn"></param>
        private void OnReceive(IAsyncResult asyn)
        {
            // first verify we received data from the correct socket.  This check isn't really necessary in this example since we 
            // only have a single socket but if we had multiple sockets, we could use this check to use the same callback to recieve data from
            // multiple sockets
            if (asyn.AsyncState.ToString().Equals("Level1"))
            {
                // read data from the socket.
                int iReceivedBytes = 0;
                iReceivedBytes = m_sockLevel1.EndReceive(asyn);
                // set our flag back to true so we can call begin receive again
                m_bLevel1NeedBeginReceive = true;
                // in this example, we will convert to a string for ease of use.
                string sData = Encoding.ASCII.GetString(m_szLevel1SocketBuffer, 0, iReceivedBytes);

                // call wait for data to notify the socket that we are ready to receive another callback
                WaitForData("Level1");
            }
        }