Multithread Server Woes

[CraigW]

Hello everyone. I don't normally post on fora but I am really stuck!

THE PROBLEM.

I need to set up a server with multiple clients talking to each other. Sounds easy? Just a matter of setting up some Sockets with DataInputStream/DataOutputStream and some threads. Unfortunately I am having difficulty with this. Here are the steps I am taking to create my application:


Steps:
Get a client and a server to talk to each other. (I can do this)
Get multiple clients talking independently to a server. (I can do this)
Get multiple clients talking to each other via a server. (CAN'T GET PAST THIS STEP!)
As above, but with clients allocated turns to post in round-robin fashion.
As above, but with client input validated.


If someone could give me advice or a pointer to a resource to solve my problem I would be very grateful. For example: should I be using a Multicast rather than DataOutputStream to send messages from a server to simultaneous multiple clients?

cheers
Craig W

[cjard]

there should be any round robining.

you should ahve this:
A pair of SocketLinker classes.. both are runnable and operate in their own thread

a main thread that accepts connections and spawns pairs of SocketLinkers

an socket linkers job is simple:
Read everything from the inputstream and write it to the output stream

you have 2 clients, A and B
and these aer represented by the sockets to which they are connected, socketA and socketB

you create a pair of socket linkers like this. remember a socket linker takes an input and output stream as creation parameters then slips into a simple loop that forwards all input to the output


new SocketLinker(socketA.getInputStream(), socketB.getOutputStream();
new SocketLinker(socketB.getInputStream(), socketA.getOutputStream();


heres a simple loop for stream forwarding:

//inputstream is called is, output is os
byte[] buffer = new byte[4096];
for(int bytesRead = is.read(buffer); bytesRead != -1; bytesRead = is.read(buffer);{
  os.write(buffer, 0, bytesRead);
}

thats it... now can you see how it links the 2 clients? the input stream of client A (what he sends to teh server) is linked to the output stream of client B (what he gets frpom the server), and vice versa

-

ill leave you to batter your head with this

[cjard]

shoot, i forgot to say that you make your sovket linkers implements Runnable interface, then put the linking loop in the run() method

then to start 2 new threads:

new Thread(new SocketLinker(A_IS,B_OS)).start()
new Thread(new SocketLinker(B_IS,A_OS)).start()

note you mustnt put:

new Thread(new SocketLinker(A_IS,A_OS)).start()
new Thread(new SocketLinker(B_IS,B_OS)).start()

because that simply sends A's data back to him and the same for b.. do you see?