public static void ReadCallback(IAsyncResult ar) { String content = String.Empty; // Retrieve the state object and the handler socket // from the asynchronous state object. StateObject state = (StateObject)ar.AsyncState; Socket handler = state.workSocket; // Read data from the client socket. int bytesRead = handler.EndReceive(ar); if (bytesRead > 0) { // There might be more data, so store the data received so far. state.sb.Append(Encoding.ASCII.GetString( state.buffer, 0, bytesRead)); // Check for end-of-file tag. If it is not there, read // more data. content = state.sb.ToString(); if (content.IndexOf("<EOF>") > -1) { // All the data has been read from the // client. Display it on the console. //Console.WriteLine("Read {0} bytes from socket. \n Data : {1}", // content.Length, content); string recievedData = content.Replace("<EOF>", ""); Console.WriteLine("Read {0} bytes from socket.", recievedData.Length); MessageParser mp = new MessageParser(recievedData); mp.parsing(); mp.DoJob(); Console.WriteLine(mp.Result_); //string sendData = "calculation queue number : " + AsynchronousSocketListener.InstrumentQueue_.Count; // Echo the data back to the client. Send(handler, mp.Result_); } else { // Not all data received. Get more. handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), state); } } }