Research And Implementation Of Web Service Composition Reliability Optimization

With the rapid development of Web service technology, service-oriented computing will serve as basic elements of application development, through the service composition to form a distributed software system and the way of the calculation of enterprise application development, become the mainstream service computing paradigm. Web Service technology uses WSDL (Web Services Description Language), UDDI (Universal Description Discovery and Integration) and other standards and protocols, solves the heterogeneous distributed Computing, code and data reuse. It has highly interoperability, platform independence and loose coupling characteristics, has become the mainstream Service Computing implementation technology. However, due to a single Web service can’t meet user’s the complexity needs, Web services, in accordance with specific rules for organic synthesis, in order to form can value-added, bigger particle size have an internal process logic combination of service composition, and through the execution of a composite service and achieve the process of business goal, is Web service composition problem. Web service composition as the SOC model of implementing the resources sharing and service the importance of enterprise application integration technology, become the main direction of Web services technology development.Web Service Quality of Service is to describe the Service’s ability to meet the demand of users, in the Web Service composition, need to consider the performance of Web service’s availability, reliability and other non-functional attributes. Reliability is the Web service in a certain time environment within the success rate of operation, is to provide Web service composition is an important measure of QoS guarantee. As Web service composition number increasing, the increasing scale of structure and complexity of ascension, how to optimize the reliability of the Web service composition becomes very important and difficulty, and in reliability optimization process may also produce the problem such as large amount of calculation, the cost is expensive. Therefore, it is necessary to research a set of suitable for Web service composition optimization theory and technology of system reliability, to meet user demand for the reliability of the Web service composition.This thesis mainly researches reliability optimization problem for Web service combination based on cost benefit coefficient. First, analysis structure patterns of service composition and related reliability function. Further more, the Web service composition method of reliability calculation is proposed and nonlinear optimization model is established on the basis of it. And then, computed cost benefit coefficient through the relationship between the cost and reliability of component service, decided the optimization schemes of Web service composition, according to the nonlinear optimization model computing the results of optimization. Finally, designed a reliability optimization system for Web services combination based on cost benefit coefficient. The system uses Java and matlab language to implement, adopts C/S structure. First, users load a workflow objects from the process in the library can be used as a Web service composition, describe workflow components in service. The second, analysis the basic structure of Web service composition, such as sequence, parallel, branch. The final, using cost benefit coefficient method to get reliability optimum of the Web service combination. The experimental results show that the rationality and availability of the approach for reliability optimization of Web service combination, can be accurate to provide service for user’s reliability optimization requirements.