Find a demo on the Internet, a lot of BBS to give an example of a socket asynchronous, I found problem: debug server receives the task can only receive the first a pack of client data, the client then sends the data service client is not received, the debugging, the service side received the first package of data is sent and then execute action, and then jump out of the debugging process,,, the trouble which great god help take a look at why the sample is as follows:
Public static void StartListening ()
{
//Data buffer for the incoming Data.
Byte [] bytes=new byte [1024].

//Establish the local endpoint for a socket.
//The DNS name of The computer
//running the listener is "host.contoso.com".
IPHostEntry ipHostInfo=Dns. GetHostEntry (Dns) GetHostName ());
IPAddress IPAddress=ipHostInfo. Expressions such as AddressList [0];
IPEndPoint localEndPoint=new IPEndPoint (ipAddress, 11000);

//Create a TCP/IP socket.
Socket listener=new Socket (AddressFamily. InterNetwork, SocketType Stream, ProtocolType. Tcp);

//to Bind the socket to the local endpoint and listen for incoming connections.
Try
{
The listener. The Bind (localEndPoint);
Listener. Listen (100);

While (true)
{
//Set the event to nonsignaled state.
AllDone. Reset ();

//Start an asynchronous socket to listen for connections.
Console. WriteLine (" Waiting for a connection... ");
Listener. BeginAccept (new AsyncCallback (AcceptCallback), the listener);

//Wait until a connection is made before continuing.
AllDone. WaitOne ();
}
}
The catch (Exception e)
{
Console. WriteLine (e. oString ());
}
Console. WriteLine (" \ nPress ENTER to continue... ");
The Console. The Read ();
}

Public static void AcceptCallback IAsyncResult (ar)
{
//Signal the main thread to continue.
AllDone. Set ();

//Get the socket that handles the client request.
The Socket listener=(Socket) ar. AsyncState;
The Socket handler=listener. EndAccept (ar);

//Create the state object.
StateObject state=new StateObject ();
State. WorkSocket=handler;
Handler. BeginReceive (state. The buffer, 0, StateObject. BufferSize, 0, new AsyncCallback (ReadCallback), the state);
}

Public static void ReadCallback IAsyncResult (ar)
{
The String content=String. The Empty;

//Retrieve the state object and the handler socket from the asynchronous state object. The
StateObject state=(StateObject) ar. AsyncState;
The Socket handler=state. WorkSocket;

//Read the data from the client socket.
Int bytesRead=handler. EndReceive (ar);

If (bytesRead & gt; 0)
{
//There took be more data, so store the data received so far.
State. Sb. Append (Encoding. The ASCII. Get string (state. The buffer, 0, bytesRead));

//Check for end - of - the file tag. If it is not there, read more data.
The content=state. Sb. ToString ();
If (content. IndexOf (" & lt; EOF>" ) & gt; 1)
{
//All the data from the then read from the client. The Display it on the console.
Console. WriteLine (Read "{0} bytes from the socket. \ n Data: {1}", content. Length, content);
//Echo the data back to the client.
Send (handler, content);
}
The else
{
//Not all data received. Get more.
Handler. BeginReceive (state. The buffer, 0, StateObject. BufferSize, 0, new AsyncCallback (ReadCallback), the state);
}
}
}

Private static void the Send (Socket handler, String data)
{
//Convert the string data to byte data using ASCII encoding.
Byte [] byteData=https://bbs.csdn.net/topics/Encoding.ASCII.GetBytes (data);

//the Begin sending the data to the remote device.
Handler. BeginSend (byteData, 0, byteData. Length, 0, new AsyncCallback (SendCallback), the handler).
}

Private static void SendCallback IAsyncResult (ar)
{
Try
{
//Retrieve the socket from the state object. The
The Socket handler=(Socket) ar. AsyncState;

//Complete sending the data to the remote device.
Int bytesSent=handler. EndSend (ar);
Console. WriteLine (" Sent {0} bytes to the client. ", bytesSent);

Handler. Shutdown (SocketShutdown. Both);
Handler. The Close ();

}
The catch (Exception e)
{
Console. WriteLine (e. oString ());
}
}