C# Socket Hello World Example

Often a better understanding of a programming concept can be had by looking at a bare bones example.  Below is such an example of using .NET sockets to establish communication between a server and one or more clients that does without the fluff.  The server code:

class Server
{
 static void Main(string[] args)
 {
  // create the listener socket
  IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
  Socket serverSocket = new Socket(ipAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
  IPEndPoint ipEndPoint = new IPEndPoint(ipAddress, 52000);
  serverSocket.Bind(ipEndPoint);
  serverSocket.Listen(100);

  AutoResetEvent connectedSignal = new AutoResetEvent(false);
  // establish connections with clients
  while (true)
  {
   serverSocket.BeginAccept(new AsyncCallback(AcceptCallback), new Tuple<Socket, AutoResetEvent>(serverSocket, connectedSignal));
   // wait here until we've established a connection
   connectedSignal.WaitOne();
  }
 }

 // asynchronous callback to accept a connection
 static void AcceptCallback(IAsyncResult acceptAsynchResult)
 {
  var connectionObject = (Tuple<Socket, AutoResetEvent>)acceptAsynchResult.AsyncState;
  // signal to the loop in Main that we've established a connection
  connectionObject.Item2.Set();

  Socket receiveSocket = connectionObject.Item1.EndAccept(acceptAsynchResult);

  // receive the data
  var readData = new Tuple<Socket, byte[]>(receiveSocket, new byte[1024]);
  receiveSocket.BeginReceive(readData.Item2, 0, readData.Item2.Length, SocketFlags.None, new AsyncCallback(ReadCallback), readData);
 }

 // asynchronous callback to read socket data
 static void ReadCallback(IAsyncResult readAsyncResult)
 {
  var readData = (Tuple<Socket, byte[]>)readAsyncResult.AsyncState;

  // handle SocketException where SocketErrorCode == SocketError.ConnectionReset 
  // to gracefully handle sudden client disconnects
  int read = readData.Item1.EndReceive(readAsyncResult);

  if (read > 0)
  {
   // write received data to the console
   Console.WriteLine(Encoding.UTF8.GetString(readData.Item2, 0, read));
   // set up to receive more data
   readData.Item1.BeginReceive(readData.Item2, 0, readData.Item2.Length, SocketFlags.None, new AsyncCallback(ReadCallback), readData);
  }
 }
}

The server will establish connections as often as their are clients.  An AutoResetEvent is used to signal when the server has established a connection with a client and should ready itself for another connection.  The client:

IPEndPoint ipe = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 52000);
clientSocket = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
clientSocket.Connect(ipe);

clientSocket.Send(Encoding.UTF8.GetBytes("Hello World"));
clientSocket.Shutdown(SocketShutdown.Both);
clientSocket.Disconnect(false);