How to name repository and service interfaces?

Question

How do you name repository and service interfaces and their implementing classes?

For example I have a model with the name Question. What would you name the

Answer 1

I personally use FooService, FooServiceImpl, FooRepository and FooRepositoryImpl.

You might argue that the Impl suffix is noise, but

• there's typically only one implementation, so there's no FirstFooService and SecondFooService
• the concrete FooXxxImpl types are used nowhere in the code except in unit tests: dependencies are injected, and their type is the interface