C# UDP Socket client and server

Question

My first question here. I am new to this kind of programming, and i've only programmed .NET web sites and forms.

Now, the company I work at, asks me to make an ActiveX component, that listens to UDP messages, and turns them into events.

The UDP msgs are send from Avaya system, so i was told that to test my ActiveX, at first I need to create an app, that only sends UDP (only one button that sends pre-defined UDP string). And then create listener socket, ordinary C# app, that will get those transmitted UDP string from the tests app. Both apps will work on the same machine.

Later, when i get this working, i need to make the listener an ActiveX component, but first things first.

I need to know if there are any good tutorials about this, and any idea on how to start? I am sorry for my ignorance, but i am really new on this and i don't really have any time to learn this since it has to be done in 2 weeks.

Thanks in advance.

edit: I managed to create 2 simple console applications, and was sending UDP messages between them successfully. The sender will be only for testing, and now I need to re-make my receiver to get the UDP message and 'translate' it to events. And lastly, to make it an ActiveX control...

Answer 1

Simple server and client:

public struct Received
{
    public IPEndPoint Sender;
    public string Message;
}

abstract class UdpBase
{
    protected UdpClient Client;

    protected UdpBase()
    {
        Client = new UdpClient();
    }

    public async Task<Received> Receive()
    {
        var result = await Client.ReceiveAsync();
        return new Received()
        {
            Message = Encoding.ASCII.GetString(result.Buffer, 0, result.Buffer.Length),
            Sender = result.RemoteEndPoint
        };
    }
}

//Server
class UdpListener : UdpBase
{
    private IPEndPoint _listenOn;

    public UdpListener() : this(new IPEndPoint(IPAddress.Any,32123))
    {
    }

    public UdpListener(IPEndPoint endpoint)
    {
        _listenOn = endpoint;
        Client = new UdpClient(_listenOn);
    }

    public void Reply(string message,IPEndPoint endpoint)
    {
        var datagram = Encoding.ASCII.GetBytes(message);
        Client.Send(datagram, datagram.Length,endpoint);
    }

}

//Client
class UdpUser : UdpBase
{
    private UdpUser(){}

    public static UdpUser ConnectTo(string hostname, int port)
    {
        var connection = new UdpUser();
        connection.Client.Connect(hostname, port);
        return connection;
    }

    public void Send(string message)
    {
        var datagram = Encoding.ASCII.GetBytes(message);
        Client.Send(datagram, datagram.Length);
    }

}

class Program 
{
    static void Main(string[] args)
    {
        //create a new server
        var server = new UdpListener();

        //start listening for messages and copy the messages back to the client
        Task.Factory.StartNew(async () => {
            while (true)
            {
                var received = await server.Receive();
                server.Reply("copy " + received.Message, received.Sender);
                if (received.Message == "quit")
                    break;
            }
        });

        //create a new client
        var client = UdpUser.ConnectTo("127.0.0.1", 32123);

        //wait for reply messages from server and send them to console 
        Task.Factory.StartNew(async () => {
            while (true)
            {
                try
                {
                    var received = await client.Receive();
                    Console.WriteLine(received.Message);
                    if (received.Message.Contains("quit"))
                        break;
                }
                catch (Exception ex)
                {
                    Debug.Write(ex);
                }
            }
        });

        //type ahead :-)
        string read;
        do
        {
            read = Console.ReadLine();
            client.Send(read);
        } while (read != "quit");
    }
}

Answer 2

Simple server and client:

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;

class Program
{
    static void Main(string[] args)
    {
        // Create UDP client
        int receiverPort = 20000;
        UdpClient receiver = new UdpClient(receiverPort);

        // Display some information
        Console.WriteLine("Starting Upd receiving on port: " + receiverPort);
        Console.WriteLine("Press any key to quit.");
        Console.WriteLine("-------------------------------\n");

        // Start async receiving
        receiver.BeginReceive(DataReceived, receiver);

        // Send some test messages
        using (UdpClient sender1 = new UdpClient(19999))
            sender1.Send(Encoding.ASCII.GetBytes("Hi!"), 3, "localhost", receiverPort);
        using (UdpClient sender2 = new UdpClient(20001))
            sender2.Send(Encoding.ASCII.GetBytes("Hi!"), 3, "localhost", receiverPort);

        // Wait for any key to terminate application
        Console.ReadKey();
    }

    private static void DataReceived(IAsyncResult ar)
    {
        UdpClient c = (UdpClient)ar.AsyncState;
        IPEndPoint receivedIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
        Byte[] receivedBytes = c.EndReceive(ar, ref receivedIpEndPoint);

        // Convert data to ASCII and print in console
        string receivedText = ASCIIEncoding.ASCII.GetString(receivedBytes);
        Console.Write(receivedIpEndPoint + ": " + receivedText + Environment.NewLine);

        // Restart listening for udp data packages
        c.BeginReceive(DataReceived, ar.AsyncState);
    }
}