I can’t decide if this is an application service, or a domain service!

Deciding whether a service belongs in the domain or service layer can be a very tough question.

I think it’s important to remember that, just because a class:

  • Deals exclusively with objects in the domain model
  • Is called in turn by other application services
  • Has no dependencies on other non-domain services

…does not make it a domain service.

Try not thinking of it as the domain layer, but as the domain model. The domain model is a very strict abstraction of the business; domain layer is just a tier in your app where the model resides. It’s a small change of words but a big difference in perspective.

Is your service actually part of the domain model, or just manipulating it?