Model Of Web Service Composition Based On Petri Net

Web services introduces the means to provide services worldwide using a set of common standards, which makes it easier for producers and consumers of information to locate each other and change information. Yet this interoperability lacks one crucial aspect necessary for complex applications: web services are stateless operations, thus only providing for small, atomic applications. But web sewices are composable, which is an important characteristic of web services. Therefore, we can through a combination of the original Web services constitute a new and more complex, more powerful Web services. Petri Net theory as an important primary mechanism of Web services composition for the rapid creation of new and more powerful Web services is critical. In this thesis, we focus on the implementation of Petri Net theory in web services composition, describing how to achieve the integrated Web services based on Petri net modeling composition of Web services. Therefore, this thesis has taken this aspect as the key research contents, mainly containing:At first, the emphasis is stressed on the discussion of several current common model of Web services composition and a model based on information Petri Net of Web services is proposed. The model using the meta-message mechanism as Petri net resources to promote the service, gives full consideration to the information and behavior, without choice of services. The meta-message mechanism can describe parellel composition and benefits the automatic composition. Then, the model supports the reuse of the composite service, applies to the construction of complex software applications.Then, concerning about the new model, it can be achieved the service cooperation. The rules of automatic service composition are proposed and the soundness and the completeness are proven, so as to ensure the correctness of using this form of services composition.At last, based on the new model, a combination of Web services system is constructed, an example also descripts the Working method of the system.