Muti-User TCP Send/Receive Sample

Question

Does anyone have a link to a video tut for showing how to do a Multi-User TCP Send/Receive Sample? I know there is a drag and drop tool you can use but Im interested in making it by hand to better understand how to program it my self. At some point I want
to use this information to make a simple game that sends and receives data packets between two machines for a simple "fighting" game.

Answer 1

conceptually, simple network programming is pretty easy. here is a excerpt from a prior post that may help you getstarted
ok, there are a few fundamentals to cover.
1) a network communication consists of:
a server program listening on one of the server's ports (in this context port and socket are synonymous).
a network path from client port to server port (I mention ports, because firewalls often filter on them, breaking the path).
a client application sending data to a local socket
a common  data format that both the client and server will use.
2) the network acts as an intermediary to pass data between systems, but the data itself is system agnostic, so theres not really such a thing a java data. just data that was put in a format/encoding by whatever language.
so your question has two parts:
1) how to send to a server socket.
2) how to format the data so that the server understands it.
In terms of sending and receiving data, the system.net.sockets library is what you want, though Cor recommends using wcf. I've not worked with it, but here is a sample I worked up while exploring the http protocol:
Module Module1
Sub Main()
Dim req As String = "GET / HTTP/1.1" & ControlChars.CrLf & ControlChars.CrLf
Using sock As New Sockets.TcpClient()
Try
Console.WriteLine("Connecting...")
sock.Connect("www.google.com", 80)
If sock.Connected Then
Console.WriteLine("Connected. Sending request...")
Dim ns As Sockets.NetworkStream = sock.GetStream()
Console.WriteLine(ReadResponse(ns))
Dim sendBytes As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(req)
If ns.CanWrite Then
ns.Write(sendBytes, 0, sendBytes.Length)
Threading.Thread.Sleep(5000)
Else
Console.WriteLine("Stream not writable")
End If
Console.WriteLine(ReadResponse(ns))
Else
Console.WriteLine("Failed to connect")
End If
Catch ex As Exception
Console.WriteLine(ex.Message & vbNewLine & ex.StackTrace)
End Try
sock.Close()
Console.WriteLine("Press Enter to exit")
Console.ReadLine()
End Using
End Sub
Public Function ReadResponse(ByVal ns As Sockets.NetworkStream) As String
Dim ret As String = "Response: "
Dim resp As String = ""
If ns.CanRead And ns.DataAvailable Then
Using sr As New IO.StreamReader(ns)
While sr.Peek <> -1
resp &= vbNewLine & sr.ReadLine()
End While
End Using
End If
Return ret & resp
End Function
End Module
it sends the data "GET / HTTP/1.1" to google, and reads the response. its just throwaway code, but should give you a good example.
so, for a p2p IM application, I would have two sockets per client, one listening for incoming messages, and one sending to the remote box's listening port.
once you have your sockets established its primarily reading and writing to the network stream that the connected sockets provide.
Look it over and see if that doesn't help address some of your conceptual questions.
Edit:
 as others have pointed out down the thread, this is far from perfect implementation, so if you are not in the us or on a slow connection, results may vary. seee below for details.