DEFINITION OF REUSABLE CONCURRENT SOFTWARE COMPONENTS

In O.O. languages with active objects, a constraint (or behaviour) on method activations is needed to avoid inconsistencies and to meet performance requirements. If the constraint is part of a class definition, the class population grows with the product of the number of behaviours. As pointed out in [Goldsack and Atkinson 1990] this undesirable growth may be controlled by separating the specification of the functional characteristics and the behavioural characteristics of a class. This work extends the concept of behavioural inheritance (b-inheritance) which provides a behaviour to a sequential class. Furthermore, the interaction between b-inheritance and inheritance is discussed. Deontic logic notation for specifying behaviour is extended to deal with the definition of more complex constraints and to improve reusability characteristics of components. The proposal is formalized by extended Petri nets and the translation into a concurrent language is outlined. The project is under development within the O.O. ADA extension DRAGOON [Di Maio et al 1989].