The Analysis Of E-Service's Behavior Interface And Applying In Service Composition

Recently, Web Service has become the main trend and research focus of Internet. The key of Web service application is to construct new application and service by connecting logically Web Services with service composition. However, service compostion is not only the enumeration or set of the services, but deal with many other technologies, such as the description of compositon processs, the interface description of service, service discovery and function match, service interaction and automatic composition. There are lots of achievement in research and industry, but still ambiguity blocks the application of Web Service and service composition. The main contributions are as follows:(1) The service interation (such as session oriented service) always is a stateful and long-lasting message exchange conversation. So the stateless static interface description is unsufficent and we need to know how the service operations can be choreographed in the context of a message exchange in which Web Service participates. More precisely we aim to describe the exernally observable behavior of Web Service, which called as behavior interface. The focus of behavior is on the temporal and logic dependencies among the messages service exchanges with one or more other services. A light-weight interface formalism based on automata is proposed to model the behavior interface of Web Service. The formalism supports the interface compatibility check between two interfaces. Traditional interface compatibility check algorithm has limitation to session oriented service. A new algorithm COMP based on the "optimical" method is proposed which precisely define and prune the behavior of composition automata. The COMP algorithm can be used to improve the precision of service discovery and provide the "design-time" check and validate for composition.(2) The Internet, which is the environment of Web Service message exchange, has no global clock and the communication protocol is not synchronous. So the pratical message interaction of Web Service is asynchronous. The behavior of service interation under asynchronous message is undecideable. We adopt the "synchronizable condition" used in protocol compatibility and analyse the composition automata behavior of COMP algorithm. At last a method is proposed to ensure the "synchronizable condition" of composition automata and the prove is provided.(3) The flat automata behavior model has limitation on description of pratical behavior interface of service, such as the mass of states, and inadequate support on language structure. In order to resolve these questions, we proposed a "structured automata" based on statecharts to model behavior interface. The structured automata can reduce state number and charts complexity effectively. Furmore, the improved algorithm of interface compatibility check and "synchronizable condition" is proposed to applied on structured automata without need not flat the structured automata.