Flexible Reactive Capabilities in Component-Based Autonomic Systems

Reactive behaviour, the ability to (re)act automatically to perform corrective actions in response to the occurrence of situations of interest (events) is a key feature of autonomic computing. In active database systems, this behaviour is incorporated by Event-Condition-Action (or active) rules. Our approach consists in defining mechanisms for their integration in component-based systems to augment them with autonomic properties. The contribution of this article is twofold. Firstly, we propose a rule model, composed of a rule definition model and a rule execution model. Secondly, we propose an architecture for the integration of active rules into component-based systems in which the rules as well as their semantics (execution model, behaviour) are represented/implemented as components, which permits i) to construct personalized rule-based systems and ii) to dynamically modify them and their semantics in the same manner as the underlying system. These foundations form the basis of a framework which can be seen as a library of components to construct the various active mechanisms. Further, the framework is extensible: additional components can be added at will to the library to render elaborate and specific semantics according to application requirements.