Should a service layer return view models for an MVC application?

Question

Say you have an ASP.NET MVC project and are using a service layer, such as in this contact manager tutorial on the asp.net site: http://www.asp.net/mvc/tutorials/iteration-

Answer 1

I suppose that depends on what you consider the "services" to be. I've never really liked the term service in the context of a single class; it's incredibly vague and doesn't tell you much about the actual purpose of the class.

If the "service layer" is a physical layer, such as a web service, then absolutely not; services in an SOA context should expose domain/business operations, not data and not presentation logic. But if service is just being used as an abstract concept for a further level of encapsulation, I don't see any problem with using it the way you desribe.

Just don't mix concepts. If your service deals with view models then it should be a presentation service and be layered over top of the actual Model, never directly touching the database or any business logic.