service repository.

Question

hundreds of our clients around the country have a vb6/MS Access app. The boss needs them to talk to each other, eg client A creates a new task in client B's database, and status updates go back to A.

I'm trying to design a WCF system that can accomplish this using a centralized service talking to a service of some kind installed on each client. What I'm wondering is, how the central system knows the address of the clients, ie determine and consume services on the fly? What's a good architecture to fit these requirements?

Answer 1

Make the clients establishing connections to the service, not vice versa. From the server you cannot ensure that the client is available (hardware up-time, connectivity, software availability...).

That either requires a persistent connnection opened by the client or the client polling the service regularly.

In general a service provides an interface without knowing anything about the clients while a client requires an interface with knowing details about the service.