2.md

Asynchronous Socket Server

Below is a modern asynchronous server using modern .NET APIs:

• Task based APIs for asynchronous accept/read/write
• Range syntax for slicing the buffer

using var listenSocket = new Socket(SocketType.Stream, ProtocolType.Tcp);
listenSocket.Bind(new IPEndPoint(IPAddress.Loopback, 8080));

Console.WriteLine($"Listening on {listenSocket.LocalEndPoint}");

listenSocket.Listen();

while (true)
{
    // Wait for a new connection to arrive
    var connection = await listenSocket.AcceptAsync();

    // We got a new connection spawn a task to so that we can echo the contents of the connection
    _ = Task.Run(async () =>
    {
        var buffer = new byte[4096];
        try
        {
            while (true)
            {
                int read = await connection.ReceiveAsync(buffer, SocketFlags.None);
                if (read == 0)
                {
                    break;
                }
                await connection.SendAsync(buffer[..read], SocketFlags.None);
            }
        }
        finally
        {
            connection.Dispose();
        }
    });
}

Asynchronous Socket Client

Below is a modern asynchronous client using modern .NET APIs:

• Uses Task based APIs to establish the connection.
• Creates a NetworkStream over the Socket in order to use CopyToAsync, a helper that makes it easy to copy content from one Stream to another.

using var socket = new Socket(SocketType.Stream, ProtocolType.Tcp);
await socket.ConnectAsync(new IPEndPoint(IPAddress.Loopback, 8080));

Console.WriteLine("Type into the console to echo the contents");

var ns = new NetworkStream(socket);
var readTask = Console.OpenStandardInput().CopyToAsync(ns);
var writeTask = ns.CopyToAsync(Console.OpenStandardOutput());

// Quit if any of the tasks complete
await Task.WhenAny(readTask, writeTask);