The Research Of Web Service Composition Based On Petri Net

With the development of information technology and Internet technology, Web service also isdeveloping rapidly. Because of the characteristics of modular and standardization, Web servicesbecome a hotspot of Services Computing research. However, a single Web service that thefunctions are limited can't meet the complex needs of business, the industry and the academic allhope to use the existing Web services to create new service that the functions are more powerful,so we introduce the concept of Web service composition.With the addition of business needs, Web service composition has become be complexincreasingly, and errors in composition are increasing. In order to design a proper Web servicecomposition, it is necessary to analyze and verify in composition process. However, there aredeficiencies in mode, analysis and verification for Web service composition, and there havebecome the key issues to be solved in service composition.Petri net as mathematical and formal modeling tools is widely used for providing a powerfulmodeling method in system analysis and verification. Petri net has many species, Colored Petri Netis a more mature system. It combines the advantages of Petri net and programming language, and itis helpful to manage and classify many system messages for the introduction of the concept ofcolor sets. Thence, there is the significance to Utilize Colored Petri Net for composition model.Firstly, this paper proposes the web service composition based on Colored Petri Net, namedWS_CPN model, and then gives the algorithms for the model detection. Utilizing the model, it iscapable to describe Web service composition clearly and intuitively. What is more, the model isalso used for analyze and verify in composition process, thus ensures the correctness and reliabilityof service composition.This paper also highlights to introduce three methods for verifying themodel, namely the method for using modeling tools, the method for using Petri net analysistechnology and the method for Petri net reduction technology, giving the idea of combining threemethods by comparison with the methods. Then, this paper provides the mapping between WSBPELprocess and WS_CPN model. It is possible to describe WS-BPEL process by the model,there is a reasoning proof for Web service composition by verifying the model. Finally, the methodfor verifying Web service composition is proposed, it ensures the correctness of Web servicecomposition, and has certain value. In addition, this paper gives an example to verify the method.