Techniques Based On Dynamic Combination Of Web Services QoS Constraints

The development of Internet brings both opportunities and challenges to the enterprises. They need to solve the problems that how to use and integrate various resources effectively in the open network environment. The proposition of Service-Oriented Architecture(SOA) brings new method to solve the problem. With the mature of Web Service standard, Web Service becomes the best choice to implement SOA. However, most Web Services are simplex in structure and function, which cannot meet the needs of enterprises’complex application. How to effectively composite various services distributed in the Internet and create powerful compositional services attracts increasing attention. With the continuous expansion and commercialization of Web Service, the enterprises want to acquire better compositional services, so they consider more about the performance of compositional services. Therefore, it is important to provide compositional services which meets users’QoS requirement.This paper aimed to study the dynamic Web Service composition based on QoS-constrained in SOA.Firstly, according to functions is imperfect and cannot meet users’requirement of QoS, this paper proposed a framework of dynamic Web Service composition based on QoS-constrained. The framework implemented SOA based on Bus, improved the UDDI to support QoS descriptions of Web Service, designed Web Service composition model by using BEPL technology, and product Web Service composition scheme with users’ need of performance based on QoS-constrained.Secondly, on the basis of introduced QoS of Web Service and extended the WSDL to support QoS descriptions of Web Service, this paper proposed a dynamic Web Service composition algorithm based on QoS-constrained. For obtaining Web Service composition scheme with optimal performance, The algorithm considered execution price, response time, service reliability, service availability, reputation as constrained condition, and used algorithm based on an improved multi-objective particle swarm optimization to compute the performance of compositional service.Finally, taking travel arrangement service as an example, this paper completed the dynamic Web Service composition system based on QoS-constrained. According to users’requirement, QoS requirement, and QoS weights, the system designed a travel arrangement process, chose Web Service composition scheme with best performance, executed the scheme on the BPEL engine, and returned the result to users. Test showed that the system can implement the dynamic Web Service composition based on QoS-constrained.