suppose if i want to develop a windows chat application then a chat server need be developed and client too. after developing chat server apps we can run that apps in a machine and chat client will be running another pc. if those pc is not in same network suppose chat server run in a USA machine and one chat client run in Germany machine and another run in UK machine. in this situation how communication will happen using internet. all the nachine have access internet so how one chat client will login to chat server and how two chat client will communicate with each other. i just want to how data will transfer from one client to another client via chat server. please give me concept or it would be better if anyone give me a reference of a any good .net based chat application where chat server and chat client will be there.........thanks.
WCF Web Service with the client polling the service (simple-basic scenario - easy to implement, not very efficient)
WCF Duplex Web Service with the server updating clients when needed (a bit more complicated)
TCP Socket-based solution, hardest to implement but permits much better control. There is a very good example in Matthew McDonald's book "Pro Silverlight 3"