I'm not sure what you are asking, but depending on their individual performance and security needs layers are usually either (a) libraries embedded into their clients, (b) services colocated with their clients, (c) services running in a separate tier, or (d) services co-located with fdbservers. In any of these cases they use the FoundationDB client to communicate with FoundationDB.
In case (c) or (d) how can a layer leverage the distributed facilities that FDB gives?
I mean if I have clients that connect to a "layer service" that is the one who talks to FDB, I have to manage "layer service" scalabily, fault tolerance etc... by myself.
Yes, and that's the main advantage of choosing (a) or (b). But it's not quite as hard as it sounds; since all your state is safely in fdb you "just" have to worry about load balancing a stateless service.
got it, what will you suggest to do something like that? a simple RPC with a good async framework I've read,
like what? an RPC service on top of Twisted for python, similar things in other languages?
