Object-Oriented Modeling with Roles

Objects relate to each other in di erent ways | serving, using, and communicating with each other. From the way in which they treat one another, objects have di erent perspectives of each other. These perspectives de ne the role that an object may play towards another. The perspectives are formed as a restricted set of methods of the object, | exactly the methods that are relevant for the relations between the objects. Di erent roles exist for di erent purposes, and the roles played by an object may change over time. The role is a powerful modeling concept in object-oriented analysis, design, and programming. A graphical notation is de ned to support static and dynamic description of roles. The notation supports generalization and part-whole hierarchies for roles, the extension of methods and active objects with roles, and the integration of roles and locality.