ACCADA: A Framework for Continuous Context-Aware Deployment and Adaptation

Software systems are increasingly expected to dynamically self-adapt to the changing environments. One of the principle adaptation mechanisms is dynamic recomposition of application components. This paper addresses the key issues that arise when external context knowledge is used to steer the run-time (re)composition process. In order to integrate such knowledge into this process, A Continuous Context-Aware Deployment and Adaptation (ACCADA) framework is proposed. To support run-time component composition, the essential runtime abstractions of the underlying component model are studied. By using a layered modeling approach, our framework gradually incorporates design-time as well as run-time knowledge into the component composition process. Service orientation is employed to facilitate the changes of adaptation policy. Results show that our framework has significant advantages over traditional approaches in light of flexibility, resource usage and lines of code. Although our experience was done based on the OSGi middleware, we believe our findings to be general to other architecture-based management systems.