Verification Technology Of Web Service Composition Based On Petri Net

With the development of Internet technology, not only the Web page documents can be accessed by the Internet, a variety of application programs provided by the companies or organizations can be accessed and employed. In the beginning of 21st century, SOA became popular because of its several advantages, such as:measurability, loosely coupled, standardization and interoperability. Web Service is the technical support of the majority of SO A. In 2001, Tim Berners-Lee, founder of the Internet advance the concept of semantic Web.Semantic Web service is the combining technology of Semantic Web and Web service. The clear semantic information of Semantic Web services improves the efficiency and accuracy of Semantic Web service discovery. OWL-S (Web Ontology Language for Services) which is the Semantic Web service description language of Service Model information is used by Petri nets for Verification of Web services composition based on behavior.Taking the reusability of semantic Web service into account, Web service generally has specific function, a single Web service can not meet the complex application of service requests, which resulted in Web service composition. Since the independence and autonomy of Web services, some Semantic Web services composition is not reliable. And it will waste unnecessary time and economic consumption if Web service composition is found not to work abnormally until the composition is invoked. It is the key to ensure the normal execution of Web services composition that verification of the combined service before invocation.In order to solving verification of Web services composition, Petri net is used to verify composition of Web service based on behavior. The first characteristic of this approach is the using of Petri net. Petri net can be used for distributed system modeling and analysis, and Petri net has the advantage of the strong ability to describe the relationship between the various structure components of system or process (such as:sequence, concurrency, conflict, and synchronization). In addition, Petri net has the same semantic consistency with its transitive matrix. The purpose of running simulation of Petri net can be achieved by the transitive matrix operation. The second characteristic of this paper is to composite Semantic Web Service based on service behavior of OWL-S description. Web Service Composition based on the service behavior involves the service of the relationship between the atomic processes, and the order of service input and output, precondition and effect after the execution. Therefore, the verification of Web Service composition Based on Behavior of services is more accuracy.The verification method of this article is that modeling semantic Web service based on service behavior as Petri net first, related conversion modeling theory is referred to some papers and is improved, and then composing Petri nets which semantic Web services are modeled as. On the basis of this, the labeled place transitive matrix is used for verification analysis of Petri net, the results of the verification analysis can tell whether the composition of Web service is deadlock or there are correct results. The specific method is to run simulations on the Petri net through the multiplication of the labeled place transitive matrix and the state set of place after the conversion from Web service composition to the Petri net. When the state set of places is no longer changed, the result of verification analysis for Web service composition can be judged according to the value of token state of the place.