Modeling And Analysis Of Web Service Composition Based-on Logic Petri Nets

With the recent proliferation and development of Web services, the number of Web services is increasing dramatically, and more and more pressure is induced to service composition, In order to eliminate the redundancy of Web Services and alleviate the burden of network, the description methods of Web services should be improved. At the same time, more and more attentions from academia and industry are paid to Service Computing (SOC), and Web service is one of the key technologies supporting SOC, however, it is difficult to meet the needs of users with a single Web service, so Web service composition is becoming popular.In this paper, the function descriptions of Web Services are normalized based on Standard Terminology of Domain Ontology firstly. Web services with the same functions are merged into a new complex Web Service. A formalizing description method of Web service is put forward based on Logic Petri Nets, this approach not only describes the input/output parameters, Quality of Service (QoS) and behavioral constraints of Web services effectively, but also describes the parameter uncertainty effectively. A formalizing expression method of User Request is given, and then the acceptability of User Request is analyzed based on logic reasoning technology. Only realizable User Request can be delivered to the system proposed in this paper, so the efficiency of Web service composition is improved effectively.Service Algebra operators are given base on LPNs, and the corresponding basic Service Algebra constructs are delivered, such as sequence construct, parallelism construct, alternative construct and iteration construct. Then the properties are analyzed, such as closure, correctness and so on. After that, Web service composition Model is given and service composition architecture is built. Algorithm based on keywords matching and semantic matching for service discovery is designed, then the correctness and feasibility of the algorithm is verified through an example, the execution process of the algorithm is also be illustrated. Through comparison with the keywords based algorithm and semantic based algorithm, indicates our service discovery algorithm has stronger service discoverability, IN order to realize Web service composition, service composition rules are given based on Service Algebra, and then the correctness and efficiency is proved.Finally, an initial implementation of Web service composition modeling tool is given, and also the integrated framework, implementation technique. User Requests can be realized in this system. Some simulation experiments are implemented, and the results show that the Web service composition method proposed in this paper has good adaptability.This paper focuses on the research of modeling Web service composition based on LPNs, emphatically resolves the problem of Web service description and composition. It has a certain value for promoting the Web service composition technology.