NewNameServiceClient creates an RPC client that conforms to the NameService interface, but delegates work to remote instances.

NewNameServiceGateway accepts your "real" NameService instance (the thing that really does the work), and exposes it to other services/clients over RPC.

NameServiceClient manages all interaction w/ a remote NameService instance by letting you invoke functions on this instance as if you were doing it locally (hence..

NameServiceProxy fully implements the NameService interface, but delegates all operations to a "real" instance of the service.