Web服务流程的结构范式及其判定算法

The Structure Normal Form of Web Service Processes and Its Testing Algorithm

服务组合是一种利用已有Web服务构建新的增值服务的有效方法,然而当前缺乏对组合产生的服务流程进行结构健壮性层次划分和判定的准则.针对上述问题,提出Web服务流程结构范式,从路径的可达性和结构冗余性两个角度将结构范式划分为四个层次.基于逻辑Petri网建模服务流程为服务网,将服务流程结构范式的判定转化为对服务网组成结构的分析.在服务网的基础上构建控制流网,从而将服务流程中的控制流和数据流进行分离.定义了控制流网语言,并提出一种通过约简求解控制流网语言的方法.通过对控制流网语言中字符序列组成结构特征的分析,获取服务网的结构性质,完成对服务流程结构范式层次的判定.给出了服务流程结构范式的定义、判定定理以及算法,并通过实例验证了文中方法对流程结构范式进行判定的可行性和有效性.

Service composition is an efficient way to construct a new and value-added service from the existing Web services.However,there are still no rules to evaluate the level of structure soundness in the service process which is generated by service composition.To resolve such problem,the structure normal form of service processes was proposed in this paper.From the accessibility of the paths and structural redundancy,the level of structure soundness of a service process was divided into four levels in the structure normal form.The service process was modeled as a service net based on logic Petri nets,and the evaluation of the structure normal form was converted to analyze the structure features of the service net.Control flow net was built based on the service net and it separates the control flow and data flow in a service process.The language of control flow net was defined and the method to obtain it based on reduction and recursion was also provided.By analyzing the structure properties of the component character sequences in the language of control flow net,the structure properties of the service net are easily obtained,and then the level of the structure normal form of the service process can be evaluated.The corresponding definitions,judgment theorems and algorithm of the structure normal form were presented.Some application examples are given to show the feasibility and efficiency of the algorithm in testing the structure normal form of the service processes.