Model, Service and the Actor
Conceptually there are many similarities between the service and model tiers in the MVCS architecture. Because of this similarity, models and services are extended from the same base Actor class. A class that extends the Actor base can serve many functions within your application architecture. Within the context of MVCS, we are going to utilize extensions of Actor for defining both the models and the services an application will need to manage data and communicate with external entities. The FAQ will refer to the model and service classes as Model and Service respectively.
Reference MVCS Implementation