Change Item Modeling Approach
Each change management object is modeled using a three-tiered approach: interface, abstract class, and concrete class, as shown in the following figure:
Change Item Modeling Approach
Interface layer
The interface classes simply implement the Persistable interface to indicate that the change management classes are objects stored by Windchill.
Abstract classes
The abstract classes implement various Windchill plug and play interfaces and enterprise package classes to obtain standard Windchill functionality. Each abstract class implements ContentHolder, which provides the ability to attach files. In addition, each abstract class extends either Managed or CabinetManaged (see the enterprise package, earlier in this chapter for an explanation of these classes). The abstract classes also contain modeled associations among change objects, and between change objects and product information objects.
Concrete classes
The concrete classes contain modeled business attributes.