Here is a sample in C#:
/*
C# Network Programming
by Richard Blum
Publisher: Sybex
ISBN: 0782141765
*/
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
public class UdpSrvrSample
{
public static void Main()
{
byte[] data = new byte[1024];
IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 9050);
UdpClient newsock = new UdpClient(ipep);
Console.WriteLine("Waiting for a client...");
IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
data = newsock.Receive(ref sender);
Console.WriteLine("Message received from {0}:", sender.ToString());
Console.WriteLine(Encoding.ASCII.GetString(data, 0, data.Length));
string welcome = "Welcome to my test server";
data = Encoding.ASCII.GetBytes(welcome);
newsock.Send(data, data.Length, sender);
while(true)
{
data = newsock.Receive(ref sender);
Console.WriteLine(Encoding.ASCII.GetString(data, 0, data.Length));
newsock.Send(data, data.Length, sender);
}
}
}