Adaptive Web Service Composition

Abstract

Service-Oriented Architecture supports sharing resources and transforming business services into a set of linked Web services. Web services rely on non-functional attributes managed through Web Service standards (WS-*) and Quality of Service (QoS) specifications. However, traditionally, the functionality related to QoS and WS-* specifications is scattered and tangled all over the main service code, making the maintenance of these Web services expensive and complex. Aspect-Oriented Programming (AOP) provides abstraction techniques and language constructs to manage and separate these crosscutting concerns from other parts of the system. This chapter focuses on explaining the concepts of dynamic and adaptive Web service composition and proposes an adaptive Web service architecture to enhance reusability of services using the Aspect-Oriented approach. This approach enables separating crosscutting concerns such as QoS and WS-* specifications in aspect Web services and integrating them with the base Web services on the fly. This architecture is based on AO4BPEL, an aspect-oriented extension to BPEL, which reduces the complexity in dynamic selection and reuse of non-functional attributes. This methodology can facilitate dynamic composition of services and business processes in on-premise and Cloud computing environments.