Manage the response message in a Java client-server application

Question

i'm working on an Java client-server application.

The client send a message sequence (the messages can be different types, i,ve got header), and listens for the replies. I've got 2 thread, one for the transmission and one for the receipts. So i need to handle the replies, in case of errors or in case of the replies doesn't arrive, for example i can try to send the message another time.

My question is.. is there any java patterns that can helps me?

i would like to handle the send and the relative repliy like a single transaction, but note that i don't need to have a synchronous communication. I send all the message in the sequence in the TX thread and wait for the replies on the RX thread.

I've thought to the mediator Pattern, but i don't know if it is the right way.

Thanks

Answer 1

If the question is purely about transmission protocol I would take a look at NAK. http://en.wikipedia.org/wiki/NAK_(protocol_message)

I have implemented a protocol I made up called JCast that sends files over multicast. The files are broken down into small fragments that are numbered. The receiving clients then respond back with any missing fragments that it did not get (these are the NAK's). The server then would resend only the NAK'd fragments.

EDIT: The benefit of NAK over ACK is that the server can send all the packets it needs to without having to wait for ACK's. Since networks are very much improved nowadays, most of the packets would arrive. The few that do not arrive would then just be resent.