Software Engineering with Objects

Work Breakdown Stages

Analysis & Design: Part Three

Define the Classes (Object Modeling)

The likely classes in the application are defined and described in the form of an Object Relationship diagram and a Class Heirarchy Diagram. Abstract classes and inheritance are shown. Composite objects are identified and also collections eg, a business unit may have several employees.

The Object Relationship Diagram below represents the business objects and their relationships

Object Relationship Diagram

An Object Relationship Diagram (ORD) is used to define the likely classes in an application. It does not show the object's data attributes or their behaviour or methods. The ORD will be further refined into Class Hierarchy Diagrams.

Class Hierarchy Diagram Diagram below represents the hierarchy as super-classes and sub-classes and shows classes that contain other classes..

Class Hierarchy Diagram

Class Hierarchy Diagrams show:

• Inheritance or 'generations' of descendent and ancestor objects, and
• Containment (or Aggregation) where some classes are made up of other classes.