The Research And Implementation Of Web Service Composition Algorithms Based On QoS

With the properties of lose-coupling and integration, now, the Web service has become to one of the best ways to realize the SOA(Service Oriented Architecture). Faced to the different requirements, it was hard that the service provider supplied a certain service for every requirement of every customer. So, integrating the current Web service resource on net to build a composed service to satisfy the requirements of customer was an effective way to resolve the contradiction mentioned above.The main concept of service composition was that the different composed plan means the different composed service which stands for the different function. With the development of Web service, there were more and more service providers and it is not avoiding that there were some services had the similar even to the same function. Which service was selected from these services to join to the process of service composition was the first problem should be solved before the composition.Based on the research about Web service composition driven by QoS, and with the foundation of workflow, we did the following research focused on the Web service composition based on QoS:Focused on the demand of the research of Web service composition based on QoS, we studied the standards of Web service and the supported technology of service composition. After referring the international standards and considering the actual situation, we built the a descriptive model for the non-function aspects of Web service based on the thinking of dividing the function and non-function of service.In order to quantity the degree of the satisfaction of customer, we considered the process of service composition, and we built multi-object optimization model and shortest path length model for Web service composition separately, and we given a strategy for service composition based on the thinking of hybrid dynamic and static.Considering the good performance of intelligent algorithm in solving the big scale problem, we brought the genetic algorithm and ant colony algorithm in the field of service composition, and we used these algorithms in Web service selection. We proposed the two times encoding model for genetic in Web service selection; realized a hybrid intelligent optimization algorithm which had the features of global searching and fast convergence abilities based on the genetic algorithm and ant colony algorithm and increased the performance of ant colony algorithm in Web service selection.Because of the defective of the traditional WSDL, we extended the descriptive capacity of WSDL, and given the descriptive structure for the aspect of non-function of service. In order to contrast the performance of composition algorithms driven by QoS directly, we designed and released a emulative system for SOA and a prototype for Web service composition management based on Jsp and Java separately.Now, both the service technology and the Web service composition are the hot research point, but there are also some problem in theory and methodology. The models, theories and methods mentioned in this dissertation had the important referenced value for the current research of Web service composition. At the same time, the algorithms and solving strategy for Web service composition in this paper also could be used to other business oriented network management (grid service, etc), so, our research had the important academic significance and big applicative prospects.