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

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.