基于WSDG的Web服务组合可靠性预测

WSDG-based reliability prediction approach for Web service composition

为了更好地对基于SOA的Web服务组合进行可靠性预测,提出了基于服务依赖图的可靠性模型.首先介绍了Web服务组合的描述语言WS-BPEL,以及用来描述服务业务流程的原子活动和结构化活动;其次在传统的控制流图的基础上提出了Web服务依赖图的概念,Web服务依赖图用来描述Web服务组合的执行行为和结构信息,包括服务名、服务类型和服务的可靠性,以及服务之间的转移概率、转移可靠性等信息;然后分析BPEL的原子活动和结构化活动的控制依赖关系,并在此基础上构造相应的Web服务依赖图.最后基于服务依赖图的遍历,应用可靠性预测算法计算Web服务组合的可靠性.实例分析结果表明,基于依赖图的可靠性预测方法具有简便性和易处理性.

In order to estimate the reliability for Web service compositions based on service-oriented architecture（SOA）,a Web services dependency graph（WSDG）-based reliability prediction model is proposed.First the description language for web service composition WS-BPEL is introduced,and the atomic activity and structural activity which describe business process for web services are presented.Then the concept of WSDG is proposed based on the traditional control flow graph（CFG）.WSDG is used to describe the execution behavior and the structural information for web services composition,such as service name,service type,service reliability,transition probability of service and reliability of transition.Moreover,control dependencies of basic activities and structured activities of business process execution language（BPEL） are analyzed and the WSDG of compositions are constructed.Finally,an algorithm for predicting the reliability of Web service compositions is presented based on the WSDG traversal.An example shows that the approach is simple and tractable.