Study On CPN In Model The Mobile Communication Service Based On PI-calculus And Its Applications

Web Services composition is the ability to create a new value-added service by incorporating some existing Web Services together. Web Services composition is usually an error-prone task, and repairing errors at services operation time is usually costly. Web Services participated in composition are often with complex operations, and these operations must be invoked according to the precisely defined scheduling rules, so it's necessary to define the choreography rules for the operations. But some existing Web Services composition languages only describe how to compose many elementary services into a composite service in syntax, but lack formal semantic, so it is difficult to analyze and verify these models built by these languages. These languages have not provided the techniques for choreographing complex operations either, and are unable to model concurrency and communication, so they are not suitable to define the choreography rules for Web Services. Formal model can solve these problems. Creating formal model for Web Services composition process can use formal techniques to analyze and verify the services composition process in order to ensure the correctness and reliability of the composition. Formal model also can define services choreography rules. This approach enables designers to test and repair design errors even before actual running of the service, or allow designers to detect erroneous properties and formally verify whether the service process design does have certain desired properties. The main contents and conclusions in this dissertation can be summarized as follows:â… . Study on Web Services Composition Based on Colored Petri Nets1. This paper proposes a CPN-based model for Web Services composition, which is capable to specify choreography rules and Web Services composition. By creating CPN model for services composition process, designers can use the formal semantic and analysis techniques of CPN to detect and repair the design errors as early as possible at design stage, thus ensure the correctness of the composition. Choreography rules define the invoking rules of WSDL operations and describe the external behaviors. Defining services choreography rules can ensure the services to be invoked correctly and allow the composition involving services with complex operations.2. Based on the Web Services composition model, this paper presents choreography rules derivation algorithm. The basic idea of the derivation algorithm is simplifying the WSCNet service composition model, while preserving its externally observable interaction behavior. Choreography rules derivation algorithm is based on CPN full occurrence graph construction. With the use of this algorithm, choreography rules can be derivated automatically from the CPN-based model for Web Services composition, and the choreography rules will be published with its WSDL interface to UDDI registry. The Web Services composition is exposed as a new Web Service for other users, and other users can use this new service conveniently, which will improve the reuse of the service.3. This paper gives the translation between BPEL4WS and CPN model. In BPEL4WS, both the Web Service composition and the choreography rules are specified as workflows consisting of activities. To represent BPEL4WS using CPN, basically we represent activities with CPN transitions. The control flow relations between activities specified in BPEL4WS are captured by CPN token firing rules. This paper considers the mostly used workflow patterns in BPEL4WS and discuss how to represent them using CPN model.4. This paper presents the steps of creating Web Services composition using the Web Services composition model. There are five steps: (1)discover component services and acquire their service descriptions including both WSDL interface and choreography rules; (2)describe the composite Service; (3)construct the Web Service composition from CPN to BPEL4WS; (4)derive choreography rules of the composite service; (5)deploy and advertise the composite service.5. In order to ensure the correctness of the Web Services composition model, it's necessary to analyze and verify the model. This paper gives the approach for analyzing and verifying the model, and designs an analysis and verification tools JCPN. JCPN can be used to detect deadlocks automatically and has also been applied intensively in the specification, design and analysis of service-oriented distributed systems. This paper designs several examples to test the functionalities of JCPN.â…¡. Study on mobile communication service based on PI-calculus and Application1. There are too many problems in mobile communication system now, so the paper proposes that we should improve mobile communication service with the thought of Web Service. Mainly Internet as a develoPIng platform, and encapsulate many Web Service with communication process, and describe these Web Services and Web Services composition by PI-calculus, so implementing every communication process by invoking Web Service or Web Service composition. Give out four examples, in order to explain how to model Web Service by PI-calculus in mobile communication process. They are: modeling mobile communication initialization connection process, modeling mobile communication process, modeling mobile communication base station switching process, modeling recalling process. Describe Web Service composition by PI-calculus, and discuss how to describe dynamic changeable service, and abstract concrete PI-calculus expression.2. In the research of mobile process calculus, process equivalence is a core problem all the time: it means when two process expression with different syntax formations are behavior equivalence. The paper summarizes some definitions about PI-calculus bisimulation. In the process calculus, popular equivalence relation as follow: bisimulation equivalence, test equivalence, trace equivalence and so on, and bisimulation equivalence is most influential of all.3. In order to remedy the deficiencies of PI-calculus, PI-calculus is mapped into Petri nets. PI-calculus is divided into the basic elements, sequence, concurrency, choices and recursive modules. These modules are mapped into Petri nets respectively, which const ruct a complicated system. Petri nets semantics for PI-calculus visually describe system structure as well as system behaviors, and the qualitative analysis of properties is proved directly on the st ructure of the nets.With the development of Web Services composition and myriads of changes on various business in mobile communication network, data fusion and business reorganization will become more and more important and contribute more to the future various industries. The results of the dissertation will contribute to the study on formal research of modeling Web Services composition based on PI-calculus and mobile communication business based on Web Services.