Finding Relationships

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Scenarios are examined to determine if a relationship should exist between two classes. Messages between objects mean that the objects must communicate with each other. Associations and/or aggregations provide the pathway for communication.

Relationships may also be discovered based on the signature of an operation. This is discussed in Chapter 7.

Relationships in the ESU Course Registration Problem

In the Add a Course Offering scenario, the communicating objects along with the relationship-type decisions that have been made are shown in Table 6-1.

Table 6-1. Class Relationships

Sending Class	Receiving Class	Relationship Type
ProfessorCourseOptions	AddACourseOffering	Aggregation
AddACourseOffering	ProfessorCourseManager	Association
ProfessorCourseManager	Course	Association
Course	CourseOffering	Aggregation

A class diagram with the added relationships is shown in Figure 6-9.

Figure 6-9. Relationships in the Add a Course Offering Scenario

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