Describing and Composing Patterns Using Role Diagrams

Design patterns are patterns of classes and objects that represent solutions to recurring design problems. They are usually described using class diagrams. Class diagrams, however, often intertwine the actual solution with efficient ways of implementing it. This paper uses role diagrams to describe and compose patterns. Role diagrams help designers focus on the collaborations and distribution of responsibilities between objects. Role diagrams also are a better starting point for composing patterns. This paper presents several examples and reports on first experiences with using role diagrams for composing patterns which have been promising.