A Reflective Framework to Improve the Adaptability of BPEL-based Web Service Composition

Web services composition is receiving significant amount of interest as an important strategy to allow enterprise collaboration. Current web services composition solutions are rather restricted and inflexible as they are based on pre-defined models of the process environment. These solutions have assumed that the information in the models and consequently the compositions remain static and unchanged throughout the life cycle of the web services composition. However, web services may run in a highly dynamic environment. Therefore, a mechanism is required to support web services composition in dynamic and flexible process environment. The reflective framework presented here aims to improve the adaptability of BPEL-based web service composition. A meta-model was defined to build the self-representation of the web services composition. The meta-model will be modified to adapt to the changing environment, and then, the reflection mechanism utilized in the framework will adjust the web services composition automatically. To ensure the correctness of dynamic adaptation, a set of constraints and a verification approach are proposed. A prototype adaptive service composition environment has been developing to implement our reflective framework and demonstrate its effectiveness on providing adaptive web services composition. In summary, it is stated that the reflective framework provides a suitable solution to the adaptive service composition and reliable control flow and data flow correctness.