Dynamic Composition Of Web Service Based On BPEL

With the development of Web Services technology,more and more web services are becoming available on the Internet. However, the function of single web service is so limited that it is rather difficult to meet complex application requirements. Therefore, it is a trend to compose web services. In the web service composition, dynamic composition of web service has better flexibility, and is also gaining in popularity.Since the existing dynamic composition of web service has the low reliability and efficiency, this essay raises a BPEL-based dynamic composition of service framework based on researching and analyzing the existing web service composition technology. This framework is composed of service provider, extended UDDI registry center and service composition engine. As a core part of this framework, service composition engine is used to establish dynamic service discovery, selection, composite service execution mechanism and so on. In the process of composition, we introduce the QoS and semantic expansion mechanism, and design service selection algorithm based on QoS.Dynamic composition of web service contains composite service modeling and executing. At the phase of the modeling, the Pservice service and element are added to the logical process. In the process of composite service execution, the Pservice service can acquire binding information of specific web service. At the phase of the executing, multiple service discovery agents run parallel and obtain services which satisfy functional requirements from service registration center. then optimal service in the QoS is selected using the service selection algorithm. At the same time, composite service is deployed to execution engine. composition engine executes an service of composite service, meanwhile, the behind services are found and selected to improve the reliability and efficiency of service composition.A real composite service is realized to verify feasibility and effectiveness of proposed composition method, The result shows that the reliability and efficiency of dynamic service composition are improved.