An Adaptation Logic Framework for Java-based Component Systems

This paper describes a Java-based framework for developing component-based software systems supporting adaptation with logic laws and considering component interactions as a first-class aspect. On the one side, the framework makes it possible to specify the logic of interaction at the component-level, in terms of input and output interfaces, the events generated and observed by a component, and related information about the management of the control flow. On the other side, it is possible to specify the logic of interaction at the inter-component level, providing a modelling and linguistic support for designing and (dynamically) programming the glue among the components, enabling general forms of adaptation, observation and construction of the interaction space. As a result, the framework supports the adaptation of components at different levels: from interoperability among heterogeneous and unknown components, to the support for dynamic introduction, removal and update of components, to general coordination patterns, such as workflow. The framework uses first-order logic as the reference computational model for describing and defining the logic of interaction: the modalities adopted by components to interact, the adaptation laws gluing the components and the interaction events occurring in the system are expressed as facts and rules. They compose the (evolving) logic theories describing and defining the interaction at the system level, and can be observed and controlled at runtime to allow dynamic re-configurability.