System Architecture

User Interface Layer

this contains boundary classes to handle input and output with external actors

Application Logic Layer

this is when the new invented control classes are added to coordinate the application logic for each use case

Domain/Data Layer 

this is the data objects from business domain form the basis of the layer or those not identified at analysis

GUI(user interface layer)

this is independant from the application / controll logic of the use cases and from the business data objects

Controll objects ( application logic layer)

concerning application / controll logic of the use cases , are independant from the Graphical user interface and business data objects.