The Service Layer Pattern in Action
As mentioned on page 133 of [P of EAA], the Service Layer pattern defines an additional layer that lives between two interfacing layers—typically, the presentation and business layers. In principle, this intermediate layer is just a collection of classes that implement the use cases of the application.
The advent of services and service orientation, though, made the whole solution even worthier and more successful. Services represent a loosely coupled counterpart to the presentation layer, and they offer an agreed-upon contract, reusability, and cross-platform deployment. And services, like plain classes, let you fine-tune the amount of abstraction you need.
Generalities of the Service Layer Pattern
The presentation ...