Web Portfolio And Transaction-based Compensation For Research Services

With the development of Web service composition technique, how to achieve the services whose credibility and qualities meeting user requirements becomes increasingly more and more important. At present, the transaction is a technical to improve system reliability and ensure that the Web service composition can be able to properly execute in any case, quality of service QoS is a metric of Web services in the non-functional aspects. However, according to the survey as the key technologies of the two type important portfolio for Web service composition-transaction and QoS, both of them as a Web service composition factor their own, but no contact between them. How to link them together to guarantee the quality of service and reliability of Web services composition, thus Web service composition technology can meet the user’s application needs is a very important issue. To solve this problem, this dissertation discusses from the following aspects:(1) Define a transaction model of Web service composition. taking into account the "non-full-no" characteristic of traditional transaction is already not suitable for practical application of Web service composition requirements, We analysis the long transaction needs and list the practical problems that need to be addressed, and give transaction definition of web service composition. Propose a service composition and compensation framework based transaction. The Architecture mass three modules: input module, portfolio management and portfolio execution module, business transaction processing module. The input module is the input part of the combined architecture including workflow, Risk level and QoS constraints. Portfolio Management module generates the Web service composition process to meet the needs based on the workflow and user’s preferences, and passes it to the Web service composition execution module. Business transaction processing module mass business transaction processing interface module, transaction services coordination module, module of business transaction, and business transaction execution monitoring module.(2) Due to BPEL support the structured process model, we propose a genetic algorithm based on BPEL tree structure and give the Web service composition process based this genetic algorithm. Define the Risk level and its corresponding transaction attribute requirements of affairs made mandatory. Give a detailed definition and elaboration on the Key parts of genetic algorithm including chromosome coding design, fitness calculation, select, crossover, and mutation operations. Finally, give genetic algorithm-based Web service composition process elaborated and give the experimental and analysis results to prove its feasibility.(3) Deal with the failure of the Web service composition-compensation process. According to the different Risk levels, corresponding to different compensation for services, give the corresponding relationship between Risk levels of compensation services. Give a compensation strategy based on the Risk level, and describe the overall compensation process of the compensation algorithm according to different risk levels. Propose the realization of the coordination BPEL and WS-C/T combined principle, illustrate the process of transaction compensation domain determine, describe the compensation behavior based Risk levels, setup task activities transaction attributes and QoS property values and prove the feasibility of the compensation process through the simulation experiment.