Generally speaking in a MVC framework we have the Controllers that do things like making sense of a request, preparing the parameters and starting an action in the business logic through some kind of "entry point".
The business logic is where the real application is described and it's usually defined in terms of services, "models" and plain classes.
My question is, what is in your opinion the correct way to build some "entry points" for the business logic? Creating some services or plain classes offering the methods? Implementing some static methods in the models?