Designing a Peer-to-Peer Chat Interface

This is an update to the previous code post on 03/22/2002. In the update, I include the sending and receiving functions. The sending and receiving file is based on my own command and can be modified according to u requirements.

The concept is described below.

Actually, u can use this kind of command to do a lot of stuff like searching files remotely, checking remote PC information and other u can think of.

This is a simple chat program, which uses an asynchronous socket to provide a connection between two machines. This program acts as a client/server, which can get connected to other PCs (installed with the same program) or wait for other PCs to connect. You can even test this program on a single PC by running the program twice. Each instance of the program listens to a port (e.g. first instance listens to port 998 and the second instance listens to port 999).

Click the listen button of both instances, enter the hostname/Host IP Address as "local" or "127.0.0.1" and Port no as 999 for the first instance (cause we want to connect to the second instance, which listens to port 999), click connect. The IP address will list 2 programs (if successfully connected). At this point, you can start sending messages.

In this program, I also demonstrated how the events are raised during connection, disconnection, sending, and receiving (like the OnConnect, OnSend... in MSVC++ MFC's socket class).

I have created a class named WSocket (not inherited from the Socket class). The public Socket object is Soc, which does all the socket tasks. I can't inherit from the Socket class, cause when the Accept()/EndAccept() method in the Socket.

Sending Client Server Receiving
Send Filename and size to Accepted the file detail
Send signal back, tell the client to start sending
Once the signal is received, start sending file data. (Block by block until the end of the file) Store to file.
Done Successfully received all

Base only returns the Socket object and causes a casting problem (as shown here).

public void AcceptCallback(IAsyncResult ar)
{
WSocket listener = (WSocket) ar.AsyncState;
WSocket myNewSoc = (WSocket)listener.EndAccept(ar);
//Cause casting problem...it won't work

The purpose of the WSocket class is to provide some custom events or some extra tasks ( u can add your function to the class if you want). First, it will be listening for the socket that keeps on waiting for other PCs to connect, once the remote client is calling, the listening socket will raise the AcceptCallback() function, and the accepted socket will put in the available WSocket array.

WSocket listener = (WSocket) ar.AsyncState;
int nSoc = GetAvailbleSocket();
SocClient[nSoc].Soc = (Socket)ListenSoc.Soc.EndAccept(ar); //the
accepted socket
SocClient[nSoc].SockRefNo = nSocRef; //keep the array refno

Any suggestion, amendment, or comment is welcome, cause I still new in C#. Together we learn, together we grow.