Aggregation Relationships
An aggregation relationship is a specialized form of association in which a whole is related to its part(s). Aggregation is known as a “part-of” or containment relationship. The UML notation for an aggregation relationship is an association with a diamond next to the class denoting the aggregate (whole), as shown in Figure 6-3.
Figure 6-3. UML Notation for an Aggregation Relationship
The following tests may be used to determine if an association should be an aggregation:
Is the phrase “part of” used to describe the relationship?
Are some operations on the whole automatically applied to its parts? For example, delete a course ...
Get Visual Modeling with Rational Rose 2002 and UML now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
