ODVP, Fall 1999. OOD introduction.

The technical aspects of the development process preceding actual coding

Understanding the world

• Understand the necessary elements within the domain
• Understand the problems that must be solved.
• Understand the collaboration between the system to be developed and the surrounding organization.

Tools:

• Interview domain experts and others
• Books about the domain
• Other written material
• Stories
• Users’ wishes
• Observe the domain yourself

Results:

• A number of specifications and analysis documents
• Specifically for the design:
• A list of concepts
• Possibly an UML-diagram giving relations between concepts

Imagine the system

• Understand the functionality of the system and decide the extent of it

Tools:

• Scenarios
• Use cases
• Prototypes
• Requirements specification
• Discussion
• Other stuff

Result:

• Event trace
• Event flow
• State machine
• Scenarios
• Use case diagrams
• Use cases
• More requirement specification
• Other stuff

Designing the system

• Important tool: Walkthrough (also called Role Play)
• Other tools and results:
• Decide which important classes and subsystem there should be
• Decide the primary functionality of these classes
• Distribute functionality over the classes
• Produce overviews of the system

Important things to consider when designing a class

• Class name
• Public methods
• Private methods (different degrees of privateness)
• References to other objects and classes (direct or indirect)
• Data that is more or less public
• Classes and interfaces inherited by the class
• Classes that inherit this class
• Purpose with the class

Important things to consider and jot down

• Which classes receive messages from which classes
• Which classes knows which classes
• Which method uses which methods in what classes
• What subsystems do we need and what are they composed of
• Inheritance hierarchies