Model And Verify The Mobile Communication Service Based On CPN For Web Service

With the development of computer technologies and theexpansion of the computer system, distributed computing has beendeveloped rapidly. Process-oriented distributed computingsupports two objects invoke each other without details; it solvesmany problems in enterprise area. Along with the age of theInternet coming, people require urgently that the integration ofdistributed system can be cross-platform, language independentand loosely coupled on the network. Web services have emerged.Web services use XML,SOAP,WSDL,UDDI as the core technology, baseon Service-Oriented Architecture (SOA) which contains serviceprovider, requester and broker, it is self-contained,self-described, modular applications, it can be described,published, found, bind, invoked and composite. Now, Web servicesbecome a hotspot of computer research.The characteristics of the Web services meet today's businessrequirements of applications integration, for its commercialvalue, the technology will affect more human and material inputs,with good prospects. However, a single Web service can't meetthe changing needs of business today, the industry and academicall hope to use the existing Web services to create new services.By integrating a number of value-added services to get a newservice, the problem of Web services composition arising from thenew topics. Web services composition faces many problems, themost important is the service description and work flow of service.How to ensure that the operation of the various Web services arecorrectly invoked, when we combine a complex Web services with other services into a new service, it requires a detaileddescription of the conversation protocol. In the process ofcomposition, how to control the whole process, it not only relyon the level of grammar descriptions, but also the semantic, whichis lack of at present. Because the composition of Web servicesis error-prone, it requires to be thoroughly verified beforebecoming operational, we must have the solution to detect theerrors. This is also the research directions of the paper.Petri nets has been developed more than 40 years ,proving itsvitality. Its network structure has the ability to describe theasynchronous and concurrency and the characteristics of graphics.Petri nets abide by the natural law, it is a good system modelingtools. Web services is also from the practical life, describingthe operation of services such as asynchronous problems is thedifficulty of the compositions, according to the characteristicsof Petri nets, we can use it to study the composition of Webservices more easily. Petri net has many forms. Colored Petri Net(CPN) is a mature system. The introduction of the concept of colorsets can describe the more complex message which used to interactbetween services. This paper is going to study the CPN-based Webservices, using CPN as the platform; we can both describe theconversation protocol and the workflow of the web service. Usingthe advantages of CPN, we can do a deeper level and more effectiveanalysis about Web Service, also assure the correctness andreliability of the composition.Whether the conversation protocol or process control, theyall have the relations with the work flow that consists activities,therefore, using CPN to simulate work flow is the cornerstone ofthis paper. BPEL is now the industry's business process flow control language, the paper is mainly for BPEL language, itsuccessfully simulates ten process by seven model, and BPELframework can be derived in accordance with the corresponding CPNmodel.After the implementation of the CPN work flow simulation,this article begin to discuss the conversation protocol. Now theindustry standard is WSDL, but WSDL the lack of Semantic. CPN canmake up for this deficiency, not only can it describe the serviceoperations port but also can it present the order of theoperations by the semantic information. Each of operations inWSDL is mapped to a transition in CPN and the messages mapped totokens. By the use of CPN token fire rules, we can express thesequence order of the implementation of the operations, inaccordance with the approach, this paper successfully proposesthe CPN-based Web services conversation protocol. Upon this,using O-Graph theory in CPN, we get the algorithm of operatingsequencing graph, which solves the problem of semantic webservices. This paper proposes a system called CPN4WS.It iscapable to describe the conversation protocol, present the workflow, model the web service and assure the correctness andreliability of the composition. We can use the system to achieveour purpose to study the web service.Finally, we implement the CPN4WS system as a graphical tool,according to the tool, we can present the Petri nets, model andverify the Web services. The paper model the mobile communicationservice, separately presents the base station service,controller service , server service and then composites them intoa new service. We also give the example that using the O-Graphtool to detect the errors in web service, proving that we can use it to assure the correctness and reliability of the composition.The technology of Web services develops rapidly, the newdemand for new issues come out one after another. Petri net theoryis mature, according to the new problem, we should use Petri nettheory to solve them timely and accurately. At the same time,Petri net theory also have its weaknesses, such as channelfunction of PI calculus theory ,which is also the popular methodto study the web service. Therefore, in the future, we must alsopay attention to other technology and other research methods sowe can improve the Petri net theory.