Research On Time Verification Of Web Service Composition Based On TCPN

With the development and wide application of Web services, it is necessary to combine share Web services to provide more powerful and complex functions. However, the Web service composition based on flow is a complex process. If a wrong service combination is executed without pre-verification, it will take a high price to repair. Therefore, the verification of Web service composition is an indispensable part. However, the work of Web Service verification mainly concentrated in the testing service functional correctness, the non-functioning attribute description and verification is relatively rare, non-functioning attribute of Web service attain the more and more attention with the development, on the one hand, the research of time management has focused on the validation workflow, consider the task implementation and time constraints in a single workflow, but it did not use WSDL, OWL-S, BPEL and other description language , restricted the practical application; on the other hand, the time verification of Web service composition flow is lacking of a comprehensive description of the service time, and did not take the delay time between services and service execution time. This paper mainly considers the time attribute verification in service composition flow, using the time OWL-S ontology, it increases the possibility of automatic composition compared previous workflow method.Firstly, in order to describe the time properties, this paper extends the service description OWL-S, adds the time properties into OWL-S description model, forms Service: Time OWL-S which is about service time, it can be a comprehensive description of service time properties and delay time between services, and takes use of time constraints Petri net(TCPN) based on the Petri nets rich in the form of mathematical models, and establishes the mapping rules and transform method from OWL-S Time process model to the time constraints Petri net, convert the issues of verifying the service composition described in OWL-S Time into the issues of analyzing time constraints Petri net.Secondly, the time conflict description in service composition is proposed, for this problem, this paper deifies time relax matrix based on the Petri nets time characteristics for implement the service time structured storage, and then proposes two algorithms for time verification in Web service composition, takes an example of algorithm for explaining the process, this method also calculates the service complete time within the specified time, it can help to remove the plan of conflict service composition and avoid the waste of Web Service resource.Finally, this paper describes the realization of extension OWL-S tools and experimental environment, and the verification process.