Please help with TCP/IP

[abdul]

Hi, I am trying to make a messenger using winsock and TCP/IP.
I just want to know that let us when the server is ofline and the client sends a message to the server. Will TCP/IP save this message and when the server becomes online, it will give that message to the server?

[parksie]

No. The packets will bounce around for a bit before timing out, and an ICMP Unreachable packet will be returned to you.

PS: TCP/IP is probably the most complex networking protocol in the history of communications so I didn't bother trying to understand it too much, so I gave a fairly high-level answer.

[abdul]

I think that when msn shows you the message that certain person is online, does it have any kind of information on the centeral server?

I am thinking:

When the client use the chat program (mine), he sends the signals to all of the other clients and the server that he is online. And let us if I am not online, I dont recieve the signal. But When I come online, I also send the signal to all of hte clients that I am now online.

Will that method work as msn sends the signals between clients?

ohh..forgot to ask that.. Can I use the chat program as both server and client? I just use two sockets - one to recieve calls and the other one to sends calls?

[parksie]

I don't know the details of the MSN protocol, but I recall someone posting a link to some details about it. It's in Internet Draft stage so that might help find something.

You'd probably need a socket per individual conversation, and one for the control (to the server).

[abdul]

I will try to find some way of chatting like msn.

I dont know why I am calling the program *a server* but I dont have any server. I just want people to contact each using the chat program

So they can be server and client at the same time

[parksie]

Most chat systems use a central server to store details of currently online users, and their IP addresses. This solves the problem of synchronisation between different users. For example - User A goes online. User B goes online. User B does not know User A's IP address, and so doesn't inform user A.

They cannot chat

[abdul]

I forgot that I will just make a simple one that asks the user to enter the ip address!

And by the way, What about the computer name? I think there are more than 1 computers with the same name..right? So do I use IP address or a computer name to connect to a machine?

[parksie]

Use IP address. Although they should be able to enter a hostname - just resolve it to the address.

[abdul]

But I am wondering what if there are more than one computers with the same hostname.

[parksie]

I don't think that's possible.

[abdul]

Woo!!

Then let us if I have two computers with the same hostnames (hostname: oemcomputer) then what do you think will happen

[parksie]

I meant fully qualified host names. For example, I'm connecting through Freeserve (an ISP over here), and my current hostname is: modem-54.white-faced-ibis.dialup.pol.co.uk

I think the DNS system rejects multiple hostnames - it would just reassign the IP address to whichever name was set last.

Or are you confusing hostnames with NetBIOS computer names? If you were running this on a local network (no DNS) and you had two computers called "oemcomputer", then neither would work.

[gwdash]

according to the MSN protocol, MSN doesn't establish a direct connection between chat clients except for voice chat, for text chat, everything is routed through what they call a "Switchboard Server", that passes traffic from person to person, allowing more that two people to chat together easily.

[parksie]

Ah...so that would be why Trillian occasionally says "lost connection to switchboard"

This is the annoying thing about MS - they do get some nice stuff done...but you never see much of it