On Various Approaches to Dynamic Adaptation of Distributed Component Compositions

We research dynamic reconfiguration of component systems in the context of dynamic adaptation. We classify various approaches to dynamic adaptation of component composition and conclude that they differ in power and complexity, yet still have significantly compatible strengths and weaknesses. Therefore, we argue for an integrated approach that implements several different approaches and leverages their compatible benefits by applying the appropriate one in a given situation. In the remainder of the paper we show how our recent research fits into this framework. This research is concentrated on Web Services as a specific type of distributed components. We explore Web Services with multiple classes of service and dynamic adaptation of Web Service compositions using manipulation of classes of service. Such an approach to dynamic adaptation is complementary to the reconfiguration of compositions of Web Services done by finding alternative Web Services and rebinding. Its benefits include adaptation speed, enhanced robustness of the relationships between components, simplicity, and low overhead. Also, providing multiple classes of service at the Web Service level has other benefits such as increased flexibility and choice for both Web Service vendors and consumers, while maintaining relatively low overhead and limited complexity of required management.