From time to time I find there is a need to build a service class. Something I can't really attach inside a model in order to respected GRASP and SOLID.
So I created a class called AccountTransferService.
From time to time I find there is a need to build a service class. Something I can't really attach inside a model in order to respected GRASP and SOLID.
So I created a class called AccountTransferService.
Are service classes good design practice ?
As long as they do not contain business logic or state but only orchestrate other components, yes. For additional information, see http://martinfowler.com/eaaCatalog/serviceLayer.html
Do they represent a Model ?
The Model in MVC is your application minus the User Interface (V+C). As such, a Service is part of the Model, but it is not a Model in the sense of a Domain Model. They are also not what frameworks like Code Igniter usually (and incorrectly) mean when they talk about models.
If a Service is not a Model what are they in a MVC arhitecture ?
See above, they part of the Model