Pascal chat program

[loop]

Simple question
the feasibility of writing a very simple internet chat program that uses a centralised server in pascal.
Me and dave are gonna attempt it but we really need to know some basics about sending data over the internet, such as how do we do it.

[Dave]

Ive got one working at the monent basicallty writing to a centralised file (when you open a new conversation it creates a new file for that convo) and then writing every second.

Its currently works but only ovewr the college network, saving ti a common drive.



im dubious about being able to do anything similar with pascal, for a start getting pascal to acknowledge the internet will take some doing, and then getting it to somehow create a file on my server :S


I think over the net we'll have to setup some sort of direct connection between the machines perhaps.

[loop]

yeah maybe pascal is too hopeful, but it looks very possible with C++, just got to learn C++, oh why must collge use such an old language.

[Aedan]

Depending on who's Pascal compiler you are using, it may well be possible.

TCP/UDP connections (Internet) are handled by something known as "sockets". If you can import Win32 calls into the Pascal you are using, then you can use the WinSock library to do some of the dirty work for you.

The basic way that sockets work for the connecting machine is kinda like this...

You initalise the socket library.
You create a socket. You will receive a number that corresponds to the socket. Don't lose it!
You build up a connection descriptor out of the remote IP (not hostname!), the remote port, and the type of connection you want (Internet generally).
You call the Connect function.
With a little luck you'll get returned a connected message.

One thing to note though, is that socket operations do not necessarily block. That means you need to use something called "callbacks" in order to program sockets efficiently. A callback is simply where the Winsock library will call a routine in your program if something occurs (Such as data arriving).

There's some information on how to do it in Pascal over at http://www.aspelin.com/programming/winsock/

no idea if it'll work, but I've managed sockets programming in a few languages.

Áedán

[Aedan]

Originally posted by Dave
im dubious about being able to do anything similar with pascal, for a start getting pascal to acknowledge the internet will take some doing, and then getting it to somehow create a file on my server :S

If you're using a centralised server, then you probably don't want to be using files! (unless for audit/logging) Use memory buffers instead, as they're vastly quicker, more efficient, and don't churn up the disk.

Áedán

[Rackne]

Chat programs are evil. Currently writing one in Java for uni. The coding itself isn't evil at all. The fact that it's a group project with 11 other people is what makes it such a nightmare.

The fact that Java has socket classes built right in makes it very simple to program. If Pascal doesn't work out I'd say learn Java over C++. But then I have issues with C++. Horrid messy language.