Thursday, April 30, 2009

Dot Net Socket Programming-2 : Asynchronous Socket Client

I just 'CTRL+C and CTRL+V'ed from client socket code on MSDN samples. The following code should be self explanatory. If I get enough time I'd write a brief description of it though.
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;

// State object for receiving data from remote device.
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}

public class AsynchronousClient
{
// The port number for the remote device.
private const int port = 5656;

// ManualResetEvent instances signal completion.
private static ManualResetEvent connectDone =new ManualResetEvent(false);
private static ManualResetEvent sendDone =new ManualResetEvent(false);
private static ManualResetEvent receiveDone =new ManualResetEvent(false);

// The response from the remote device.
private static String response = String.Empty;

private static void StartClient()
{
// Connect to a remote device.
try
{
// Establish the remote endpoint for the socket.
IPHostEntry ipHostInfo = Dns.Resolve("localhost");
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint ep = new IPEndPoint(ipAddress, port);

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

// Connect to the remote endpoint.
client.BeginConnect(ep,
new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();

// Send test data to the remote device.
Send(client, "Data Send to local server.");
sendDone.WaitOne();

// Receive the response from the remote device.
Receive(client);
receiveDone.WaitOne();

// Write the response to the console.
Console.WriteLine("Response received : {0}", response);

// Release the socket.
client.Shutdown(SocketShutdown.Both);
client.Close();

}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;

// Complete the connection.
client.EndConnect(ar);

Console.WriteLine("Socket connected to {0}",client.RemoteEndPoint.ToString());

// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void Receive(Socket client)
{
try
{
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;

// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void ReceiveCallback(IAsyncResult ar)
{
try
{
// Retrieve the state object and the client socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;

// Read data from the remote device.
int bytesRead = client.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));

// Get the rest of the data.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,new AsyncCallback(ReceiveCallback), state);
}
else
{
// All the data has arrived; put it in response.
if (state.sb.Length > 1)
{
response = state.sb.ToString();
}
// Signal that all bytes have been received.
receiveDone.Set();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void Send(Socket client, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);

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

private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;

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

// Signal that all bytes have been sent.
sendDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

public static int Main(String[] args)
{
StartClient();
Console.ReadLine();
return 0;
}
}