Com S 362 Lecture Notes for Sep 08
Domain Models

Reading: Larman Chapter 9

Remember: Software Process Models, Requirements, 
Specification, Requirement Elicitation, Use Cases,
Scenarios, Actors, Type of Actors

Recap:

Use cases:  

Scenario = Description of [Actor --fulfill--> Goal]
Use Case = [1 or more Scenario]

Three Kinds of Actors:

Primary: One who uses the machine to fulfill goals 

Supporting Actor: Provides a service to machine so that 
the machine can fullfill Primary Actors' goals

Offstage Actor: Has an interest in the behavior of 
the use case

Today's Lecture:

Transition to object-oriented analysis. Requirement 
analysis that we studied so far were general.

Domain Model: 

When: Often constructed during object-oriented analysis

Why: 

- Understandability: Analyst is not familiar with the domain. These
models help to understand the concepts in the domain and 
also to document relationship between concepts.

- Helps lower representational gap between domain and software

What: A visual representation of conceptual 
classes or real-situation objects in a domain. Also,
referred to as the visual dictionary of the noteworthy
abstractions, domain vocabulary, and information content
of the domain.

Domain Models consists of:

- Conceptual classes
- Attributes of these conceptual classes
- Association between these conceptual classes

Conceptual Classes:

An idea, thing or object in the domain. Often understood in
terms of its symbol, intension, and extension.

Symbol: word or images representing a conceptual class.

Intension: the definition of a conceptual class.

Extension: the set of examples to which the conceptual class 
applies.

Finding Conceptual Classes:

 - Reuse or modify existing models
 - Use a category list
 - Identify noun phrases