Toward Supporting Unplanned Dynamic Changes of Service-Based Business Processes

Service-oriented architecture (SOA) has become an application development paradigm widely recognized both in academia and in industry. Although SOA-based applications may vertically implement business processes through the composition of loosely coupled services, they have to face frequent changes, such as unavailability of service (due to the uncontrollable, dynamic, and distributed environments) or dynamic replacement of service (due to specific user requirements). This indicates that the service compositions are expected to be adaptable enough to cater to such changing situations. In this paper, we propose an approach to supporting unplanned dynamic changes of service compositions by combining variability management and dynamic binding. The proposed approach introduces the concept of abstract proxy services in a variability-supporting service composition language, namely VxBPEL, and provides a mechanism to support variation design and dynamic binding for unplanned changes at run time. To realize the proposed approach, we have developed a service composition engine that supports abstract proxy services and their run-time replacement via service discovery or user intervention. Finally, a case study has been conducted to demonstrate the feasibility of the proposed approach and quantify the performance overhead resulting from runtime variability management and dynamic binding. The experimental results show that the proposed approach overcomes the limitation of imperative variability-based approaches in handling unplanned dynamic changes and further enhances the dynamic adaptability of VxBPEL-based service compositions.