Web服务工作流中基于信任关系的QoS调度

QoS Scheduling Based on Trust Relationship in Web Service Workflow

不确定或恶意欺骗的服务节点对服务工作流调度的影响常常是致命的,因此仅从性能QoS角度研究工作流调度存在片面性.针对当前工作流调度中存在信任机制与调度机制分离的缺陷,提出了基于信任关系的工作流QoS调度方法,通过建立信任调度模型,利用D-S理论进行信任度计算,同时阐述了工作流路径级信任关系的概念及其传递、合并的计算方法,并将信任关系作为QoS调度的重要指标来综合考虑.该方法在保证工作流性能QoS要求的同时兼顾信任QoS的要求,大量实验结果表明:该算法较传统的基于性能QoS的调度而言,不仅具有更优的QoS性能,而且显著提高了调度的成功率.

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 pathlevel 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 work-flow 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 performanee-QoS.