Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design and the Unified Process, Second Edition

16.1. Responsibilities and Methods

The UML defines a responsibility as “a contract or obligation of a classifier” [OMG01]. Responsibilities are related to the obligations of an object in terms of its behavior. Basically, these responsibilities are of the following two types:

• knowing

• doing

Doing responsibilities of an object include:

• doing something itself, such as creating an object or doing a calculation

• initiating action in other objects

• controlling and coordinating activities in other objects

Knowing responsibilities of an object include:

• knowing about private encapsulated data

• knowing about related objects

• knowing about things it can derive or calculate

Responsibilities are assigned to classes of objects during object design. For example, I may ...