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Information Systems Analysis and Design
CSC340
III. Class and Object Diagrams
Classes, Attributes and Operations
Objects and Multi-objects
Generalization and Inheritance
Associations and Multiplicity
Aggregation and Composition
How to Use Class Diagrams
© 2001 Jaelson Castro and John Mylopoulos
Class Diagrams -- 1
Information Systems Analysis and Design
CSC340
Classes
A class describes a group of objects with
similar properties (attributes),
common behaviour (operations),
common relationships to other objects,
and common meaning (“semantics”).
For example, “employee: has a name, employee# and
department; an employee is hired, and fired; an employee
works in one or more projects”
©2003 John Mylopoulos
Class Diagrams -- 2
Information Systems Analysis and Design
CSC340
Finding Classes
Finding classes in use case, or in text descriptions:
Look for nouns and noun phrases in the description of a use
case or a problem statement;
These are only included in the model if they explain the nature
or structure of information in the application.
Don’t create classes for concepts which:
Are beyond the scope of the system;
Refer to the system as a whole;
Duplicate other classes;
Are too vague or too specific (few instances);
Finding classes in other sources:
Reviewing background information;
Users and other stakeholders;
Analysis patterns;
CRC (Class Responsibility Collaboration) cards.
©2003 John Mylopoulos
Class Diagrams -- 3
Information Systems Analysis and Design
CSC340
StaffMember Class for Agate
For example, we may want to represent the concept of a staff
member for a company such as Agate in terms of the class
StaffMember.
StaffMember
Attributes
(optional)
Name (mandatory)
staffName
CalculateBonus()
ChangeGrade()
©2003 John Mylopoulos
Operations
(optional)
Class Diagrams -- 4
Information Systems Analysis and Design
CSC340
Names
Every class must have a unique...