Aspect-oriented Approach for Non-functional Adaptation of Composite Web Services

We provide a novel approach for specifying and relating non-functional properties for distributed component Web services that can be used to adapt a composite Web service. Our approach uses distributed aspect-oriented programming (AOP) technology to model an adaptive architecture for Web services composition and execution. Existing Web service adaptation mechanisms are limited only to the process of Web service choreography in terms of Web service selection/invocation vis-a-vis pre-specifled (Service Level Agreement) SLA constraints. Our system extends this idea by representing the non-functional properties of each Web service - composite and component - via AOP. Hence our system models a relation function between the aspects of the composite Web service, and the individual aspects of the component Web services. This enables mid-flight adaptation of the composite Web service - in response to changes in non-functional requirements - via suitable modifications in the individual aspects of the component Web service. From the end users´ viewpoint, such upfront aspect- oriented modeling of non-functional properties enables on-demand composite Web service adaptation with minimal disruption in quality of service.