data synchronization between two client machine over the internet by Webservice?

[C# Programming]

suppose a company has two branches in UK & US. say two windows client apps are there and they would like to transfer data to each other and their local data will be synchronozed with those data. so please guide me how can i develop a webservice which will work as a bridge and accept bulk data from client a and pass to client b vice versa. if i can get the concept then i can develop a good synchronization system by webservice. where webservice will play the role like bridge who can accept bulk data and also pass bulk data to other client.
please help me to accomplish this task.

Thanks in Advance

tbhattacharjee