Web Service Choreography Protocol Mapping Model And Implementation Mechanism

Service choreography and service orchestration are two different levels of service composition standards, their languages respectively are WS-CDL and BPEL, choreography must comply with the interactive protocol in the process of producing orchestration, service choreography protocol mapping has always been the hot spot of the service composition research. Service orchestration can be divided into centralized and decentralized, because the definition of choreography language and orchestration language syntax are not rigorous, it’s hard to convert WS-CDL to BPEL directly in the process of decentralized orchestration mapping, at the same time traditional solutions the lack of specific and consistent verification algorithm theory, therefore, providing a correct and reasonable mapping algorithm and consistency verification protocol mapping theory becomes a key issue, this paper proposes a role-based protocol mapping model to solve the problem above.Firstly, according to the structural characteristics of the service choreography protocol, WS-CDL can be divided into structural part and behavioral part, while taking advantage of Pi-calculus and the theory of finite state machine, we can get the structural and behavioral model, further the structural and behavioral mapping model and corresponding algorithms can be acquired through the introduction of intermediate role mapping theory, these two models constitute the role mapping model of protocol. Role mapping theory not only solves the directly syntactic conversion problem of language WS-CDL and BPEL, but also conforms to the character of distributed service orchestration that each participating role separately processes the information.Secondly, analyze the service choreography WS-CDL protocol through a purchase order service instance and process the protocol from centralized and decentralized perspective, then structural and behavioral mapping model were obtained after treatment of the two methods, ultimately we can achieve the distinction in the implementation.Finally, on the basis of the examples of role mapping rules, We can verify the consistency of Port message type and behavior, meanwhile making use of Pi-calculus model validation tools MWB can carry out bisimulation verification about the model that analyzed from instance, indicating global and local action consistency, eventually it is concluded that the validity of the mapping rules and the realizability of the algorithm.