Design patterns·Modelling the domain
there is one method per use case, it opens the transaction, calls the model, and contains no business rules itself.
Service layer
Also calledapplication layer, service facade
A boundary layer defining an application's operations as a set of use-case methods, coordinating transactions, security and the domain objects that do the work. It is what keeps controllers thin and what gives an application an API independent of its user interface. It is also the layer that quietly absorbs domain logic until the model beneath it is anaemic, which is the failure to watch for.