Chinese Journal of Computers   Full Text
Title	QoS Scheduling Based on Trust Relationship in Web Service Workflow
Authors	HU Chun-Hua1),2) WU Min2) LIU Guo-Ping2），3)
Address	1)(School of Computer and Electronic Engineering, Hunan University of Commerce, Changsha 410205) 2)(School of Information Science and Engineering, Central South University, Changsha 410083) 3)(School of Electronics, University of Glamorgan, Pontypridd CF37 1DL, UK)
Year	2009
Issue	No.1(42—53)
Abstract &   Background	Abstract The influence of the uncertain or deceiving service nodes on the Web service workflow scheduling performance is generally fatal, so the problems of QoS scheduling can not be completely solved by the performance-QoS. The paper is concerned with the problem that trust mechanism is largely ignored in existing scheduling algorithms of service workflow. A novel algorithm of service workflow scheduling is proposed based on truth relationship in Web service workflow, and the trust value is computed by D-S theory. At the same time, the workflow path-level trust concept and the trust transfer are introduced, and the trust relationship is taken as an important parameter for QoS scheduling. The algorithm satisfies both the requirement of workflow performance-QoS and the requirement of trust-QoS. The experimental result shows that the new algorithm can obviously enhance the success rate of the service workflow execution, and it has better overall performance in other aspects such as executive time, stability and so on, compared to the traditional algorithm based on scheduling of performance-QoS. Keywords Web service; workflow; trust; QoS scheduling; Dempster-Shafer theory Background The Web service rapidly develops as a new style of Web application pattern lately. In practice, one Web service can only provide a single function, and it can’t satisfy the requirement of the complex application. So it has become a new research focus that how to integrate the function of single service forms a new powerful service in order to satisfy different users’ application requirements. The Web service workflow is an important means that make the service resources in the Internet cooperate with each other. Multi-services in service workflow will be assembled into a much more granularity increment service or system, but trust mechanism is largely ignored in existing scheduling algorithms of service workflow at present. The influence of the uncertain or deceiving service nodes on the Web service workflow scheduling performance is generally fatal, so the problems of QoS scheduling can not be completely solved by the performance-QoS. The paper addresses a novel algorithm of service workflow scheduling based on truth relationship in Web service workflow, and the trust value is computed by D-S theory. At the same time, the workflow path-level trust concept and the trust transfer are introduced, and the trust relationship is taken as an important parameter for QoS scheduling. The algorithm satisfies both the requirement of workflow performance-QoS and the requirement of trust-QoS. This work is partially supported by the Natural Science Foundation of China for Distinguished Young Scholar under grant No.60425310, the National High Technology Research and Development Program (863 Program) of China under grant No.2006AA04Z172, the National Natural Science Foundation of China under grant No.60674016, the China Postdoctoral Science Foundation under grant No. 20080440988 and the Natural Science Foundation of Hunan under grant No.05JJ40103.