基于回溯树的语义Web服务自动组合优化方法

Automatic Composition Optimization Method of Semantic Web Service Based on Backward Tree

针对现有基于图搜索的语义Web服务组合方法存在组合成本高且效率低下的问题,提出基于完备回溯树与用户请求输入闭包的语义Web服务自动组合优化方法。利用RICC算法构造用户请求输入闭包,在C_CBT_OVGP算法中,根据输入闭包判断用户请求是否能够在语义Web服务规则库中得到满足。当不满足用户请求时,算法直接结束,无需进行回溯树构建。当满足用户请求时,在回溯树的构建过程中,通过输入闭包和新增节点对象集合对回溯树实现剪枝操作,以避免节点在多个回溯树分支上重复构建。实例分析结果表明,优化方法能有效处理不可满足的用户请求,从而提高服务组合效率。

Aiming at the problems of high cost and low efficiency in existing semantic Web service composition method based on graph search, this paper proposes an automatic composition optimization method of semantic Web service based on user request input closure and Complete Backward Tree（CBT）. This method uses Request Input Closure Constructor （RICC） algorithm to construct user request input closure and determines whether the user requests can be met in the semantic Web service rule repository based on user request input closure in Closure_Complete Backward Tree Optimal Valid Generation Path（C_CBT_OVGP） algorithm. When user request is not satisfied,it illustrates the request without a solution and then ends the algorithm. Otherwise,it prunes the backwark tree by user request input closure and setting object sets of new nodes so as to avoid unnecessary repetition to build the same node on a number of different branches. Example analysis result shows that the optimization algorithm improves the efficiency of semantic Web service composition, especially for dissatisfied user request.