CHAT PROGRAM -- Problems with multi-users

[Magnadamus]

I've been working on a chat program today. Simple, just learning the NET commands really. But I'm wondering how/if it is possible to have multiple users connect to the server. It works with one person fine, but how can I make it so I can have 2, 3, 4+ users?

[Tony]

You've got to connect to different ports

[Magnadamus]

So each client has to connect to the server using a different port? Can the two clients talk to each other through the server?

[Tony]

indeed.

What you want to do is to relay (as in IRC) the message recieved to all the users connected to the server.

There are some tricks to getting users to connect to the server on different ports. You can start out with hardcoded values for testing purposes (knowing that it will work). Later the server could have a dedicated port to which the user connects.. at that point the server lets the user know of the next available port and disconnects the user, letting another one connect to the same known (and now free again) port. The first user then redials to the recieved port number, trusting the server to be available. (you should not have any problems if you don't have many clients connecting simuntaniusly)

[Magnadamus]

Alright, thanks... I'm not sure how I'm going to do this but I should be able to figure it out. What will happen later on though, if I have a lot of connections?

[Tony]

Don't worry about that for now.

[TokenHerbz]

can you just *connect* to the internet??

or do you need to purchase a server to use?

How does that work, can u make a chat that works free?

[[Gandalf]]

You can't just *connect* to the internet, because you are connecting to nowhere. The internet is millions of computer, servers, and other things all joined together.

You can either buy (or just use a free) server, or you can just connect the two computers directly. That's the whole thing of an ip (internet protocol) address, each computer connected to the internet has one (therefore you can connect to each computer connected to the internet).

[TokenHerbz]

ok, can you explain to me about ports?

[[Gandalf]]

Quote:

Definition: A port number represents an endpoint or "channel" for network communications. Port numbers allow different applications on the same computer to utilize network resources without interfering with each other.

Port numbers most commonly appear in network programming, particularly socket programming. Sometimes, though, port numbers are made visible to the casual user. For example, some Web sites a person visits on the Internet use a URL like the following:

http://www.somesite.com:8080/

In this example, the number 8080 refers to the port number used by the Web browser to connect to the Web server. Normally, a Web site uses port number 80 and this number need not be included with the URL (although it can be).

In IP networking, port numbers can theoretically range from 0 to 65535. Most popular network applications, though, use port numbers at the low end of the range (such as 80 for HTTP). The port number is included as a field within the header of each IP packet.

[Tom West]

If you want to connect multiple users, you are going to have to learn concurrent programming. It's not much fun, but essentially your server will have one process that is continually listening at a port. Note, that there isn't any need to use more than one port.

Look under process for information on concurrency.

However, the previous poster is right. Get it working for one user (you can use the chat program provided as a Turing example for starters) and understand it well.

Then learn about processes to add multiple users. It's definitely non-trivial.

[Token]

just in case your question hasnt yet been answered, you should have the main computer set as the server, most likely yours. and have that computer connect to your first client through a set port, we'll say for example 80, once it connects to the host/server. the server sends back the number of the next open port to connect to, say 81 for example, then client 1 disconnects and reconnects on port 81, client 2 connects on port 80, gets the next open port number, and connects on it. every time somone sends a message, it is sent to the server and then the server echoes it off to all the other clients. hope this helps, if you have any questions i'd be happy to help, or even work on some basic code.

[[Gandalf]]

Tony wrote:

There are some tricks to getting users to connect to the server on different ports. You can start out with hardcoded values for testing purposes (knowing that it will work). Later the server could have a dedicated port to which the user connects.. at that point the server lets the user know of the next available port and disconnects the user, letting another one connect to the same known (and now free again) port. The first user then redials to the recieved port number, trusting the server to be available. (you should not have any problems if you don't have many clients connecting simuntaniusly)

Tom West wrote:

essentially your server will have one process that is continually listening at a port. Note, that there isn't any need to use more than one port.

I think those answer the question. No need to revive a topic if one of the above posts is very similar to your own .

[Token]

oops, i missed that post, i've been out of the forums for a month or so so i was just trying to get back into it before school starts