Guidelines:  Association in the Business Object Model

Association

An association from class A to class B in the business object model indicates that A or A's objects hold a reference to B or B's objects. An association has a name and a multiplicity. The multiplicity defines how many objects of the connected class can be connected.

Topics

• Explanation
• Roles

Explanation

An association represents structural relationships between instances of business workers and business entities in the business object model. It is information that must be preserved for some duration, and does not simply show procedural dependency relationships. Each association has a name and a multiplicity. The multiplicity defines how many objects of the connected class can be connected. It is either a constant or a range (e.g., 0..5) that shows the number of objects that can be connected.

Example:

An agent who checks in airline passengers follows a set of instructions that describe his activities in the check-in business use case. Each employee acting as a check-in agent should know these procedures by heart, in order for the check-in use case to work smoothly. The business worker class Check-in Agent should have an association to a business entity class representing the set of instructions.

Roles

Some types of associations may have a rather broad interpretation. For these types, it is important that you specify the particular interpretation in each case. For this purpose, the roles that involved parties play in the association can be specified. If this is not sufficient to describe the association, the association can be given a name as well. Avoid names like "has" and "contains" which do not add any information to what the association already indicates.

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