Guidelines: Communicates-Association in the Business Use-Case Model

Communicates-Association

A communicates-association between a use case and an actor indicates that an instance of the use case and an instance of the actor will interact.

Business actors interact with the business by sending and receiving messages. Both parties can take the initiative to interact.

To fully understand the role of a business actor, you must know in which processes the actor is involved. This is shown in by the communicates-association between the business actor and the business use case representing the process. The communicates-association indicates the existence of an interaction.

The multiplicity of the association shows how many instances of a business use case one instance of a business actor can interact with at the same time; conversely, it shows how many instances of a business actor one instance of a business use case can interact with.

Example:

When an instance of the business actor Passenger approaches the check-in counter and hands over his ticket and baggage, he sends a message to an instance of the use case Individual Check-in. At the end of the check-in procedure, the business use case will print out and hand over a boarding pass, and one or more customer claim checks to the passenger. The Passenger can only communicate with one instance of Individual Check-in. Thus, the multiplicity of the relationship is [1].

A Passenger who wants to check-in at the airport will interact with the use case Individual Check-in.

When an actor and a use case interact, it can be done using different media. For example, telephone, fax, mail, and e-mail. One or several messages can be sent, but there is only one communicates-association between the two.