关键词: Web服务, Petri网, 服务可替换性, 互模拟

Abstract: Aiming at the service replaceability problem in service composition,a Petri net model-WS_Net based on workflow net and open net was presented which was oriented to modeling the information about internal behavior and interface of Web services.WS_Net could describe the common services composition modes such as sequencing,iteration,concurrence,call,and selection accurately.The definition of bisimulation equivalence about interface transitions abbreviated to interface bisimulation between two WS_Nets was presented based on the concept of Petri nets bisimulation.Two web services could substitute each other context independently which were modeled by WS_Net and satisfied interface bisimulation equivalence relationship.Two type reduction rules suited for WS_Nets were presented,one was the reduction rules concerning the inner transitions only and the other was the reduction rules concerning the inner and interface transitions.The WS_Net reduced by the reduction rules was interface bisimulation with the original one.The reduction methods reduced the complexity of analyzing substitutability of Web services.

Key words: Web services, Petri nets, services substitution, bisimulation