Role-centered design for evolution

The concept of roles in a model-based design process is discussed in this article. It is shown that roles can positively contribute to, easier discovery of the right level of abstraction in a design, thus better communication between team members or designer and reuser, and raising the reusability as well as the evolvability of a component. The role concept is compared to the well-known class concept of object-oriented design and to the interface concept of the Java programming language. It is also stated that objects, being instances of classes, can take on different roles during their life-time, and-vice versa-roles can be fulfilled by different objects. The paper takes a look at design patterns, too, as well as at the Unified Modeling Language (UML) and relates them to the role concept. This is not an experience report, but rather a programmatic view at some requirements that have become important for the design of long-lasting CBS components which are designed for evolution. These requirements are accompanied by suggestions for the designers of modeling and programming languages.