Semantic-based Web Services Composition In P2P Environment

Web Services (WS) and Peer-to-Peer (P2P) Computation are both hotspots in Computer Science all over the world. Some researchers have successfully leveraged WS and P2P to solve the problems such as the reliablity and scalability of the traditional WS mechanism. In addition, the characteristics of WS make itself very suitable for the integration of busyness application, but one alone WS is very easily restricted to its capability, so both the industry and academe hope to realize some new services for the complex requirements by composing the existing WSs. This makes Web Services Composition (WSC) becomes the hotspot in WS, and the trend of WSC within P2P environment is inescapable in the research area combining WSC and P2P.WSC means that selecting some simple and usable WSs in the Internet and composing them in order to generate some new WSs. Research work indicates that there are many key issues in the process of WSC, such as dynamic service discovering, composed service execution and composed service transaction processing, all of which are based on service description language. Using Web Ontology Language for Services (OWL-S) to describe Web Services improves the machine-understandability of WS. In order to complete WSC, the method of creating maps between OWL-S documents of different WSs is adopted, solving the problems in the process of WSC. And besides, expanding the ontology of OWL-S could solve the available time conflict problem in WSC.In order to benefit from the P2P Network, a semantic-based WSC model in P2P environment is presented, in which the Web Services publication, compostion and invocation could be realized. A prototype named WebPeer based on this model is implemented in JXTA platform, realizing the service publication by publishing OWL-S document and implementing the service composition and invocation by using some third-party softwares, such as Protégéand OWL-S Editor Plugin.