Business logic and services

In a three-tier/multitier architecture (UI/Logic/DAO/Domain model), can services be considered as belonging to the business logic layer or are they开发者_StackOverflow situated as something separate ?

---

You will probably find that a fairly generic word like "service" means different things to different people.

I think of a service as something that orchestrates the logic exposed by business objects (or other services) to implement a useful task (such as a business process). So, for me, a service is a consumer of the business logic layer (and probably of support aspects such as logging).