Research On Semantics-Based Web Service Discovery

Service discovery is one of the crucial issues for service-oriented architectural model. Recently it is towards semantic discovery by which semantic descriptions are the basis for service matchmaking instead of simple search based on service attributes. OWL-S, which comprises three profiles, is a widely adopted semantic specification for Web Services. Among those profiles, service profile includes service's functional information and nonfunctional information. It is usually used in service maintaining and matching. Process model is the profile that describes dynamic behaviour of Web Services in terms of functional aspects and process flows. It is generally aiming for service enactment, composition, and monitoring. This paper presents a new approach making web service discovery based on combination specification. This combination specification, which can be described by rules, shows how simple components are composed into a service. The information of web service excution process is expressed by rules and described by process model of OWL-S. A service consumer can query a Web Service with a particular process detail and rule reasoning. Matchmaking will be based on flexible ontological matching and evaluation of constraints on the functional behaviour and process flow of the Web Service. In the paper, A new discovery framework is proposed. In technical, it includes two aspects: service description and service matchmaking. The contributions of the paper are as follows:1) It designs a Semantic Web rule markup language——SWRL+ based on the current W3CWeb ontology language——OWL and SWRL. OWL's semantics is limited to description logic,which cannot capture semantics of arbitrary rules. Therefore, SWRL+ is designed. Its syntax extends OWL and its semantics extends description logic and Horn rules. It does not only provide a logic layer on top of ontology layer for Semantic Web architecture, but also lays the foundation fo extension of OWL-S, the current Semantic Web service model.2) It proposes a new Semantic Web service model called OWL-S+ by enriching OWL-S with the expression power of users' preferences. OWL-S+ model and the corresponding OWL-S+ ontology in SWRL+ language are defined. The new model contains formal description of user preferences in addition to description of services. It can support automated services discovery better than OWL-S, since user preferences affect how to select services.3) A method for automating services discovery is put forward based on OWL-S+ and composition specification. For the user preferences described by rules, we use the method of reasoning: fact is the information user gives, and the rules are transferred from service process. As the number maybe in it, we present a matching criteria of numerical ranges. And algorithm based on label graph similarity is for semantic information, as the common principle of user preferences.4) The discovery framework is designed, and the frame diagram is present. We give the meaning of every step in the frame. And also, we design several modules. It follows the order: first service description, then service maintaining, and then service matching.