Towards a New Role Paradigm for Object-Oriented Modeling
In this paper, we consider the framework of “complex” information systems, related to biology, geographical information, multimedia, etc. Apart from being inherently complex, objects of these domains are evolutive, and related applications require more and more often to take into account this functionality, in the same way that reusability and extensibility currently are.
What does it mean exactly to bring evolution in a formalism as a basic functionality? It means proposing, from the very first step of analysis and modeling, a way to express that future objects will, on one hand be persistent, and on the other hand be able to evolve through their life. This can be realized by allowing them to dynamically gain or loose some pieces of structure or behaviour aspects.
This capability is practically added by taking into account the “role” notion as a complement of the notions of concept or class. In traditional class-based models, an object is linked to a single class (its generating abstract model), according to the mono-instanciation principle, and this class determines the object’s structure and behaviour during its lifespan.
Indeed, some propositions, as that of P. Coad , suggested that objects could turn up to play several roles (cf.figure 1), but the role is considered as a concept located on the same level as the class.
KeywordsObject Database Role Hierarchy Animal Class Predator Prey Class Perspective
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