Automated Web Service Composition and Execution Based on Semantic Web Technology

• Main Authors: Hsin-Ying Tai, 戴欣瑩
• Other Authors: Yih-Kuen
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/79270718715671566901

碩士 === 國立臺灣大學 === 資訊管理學研究所 === 95 === Web services provide an implementation architecture for a distributed information system. As Web services emerge and expand, they can be used and be re-composed as a new Web service to complete complicated tasks. Discovering expected services and composing different services are great challenges. However, with Semantic Web technologies, Web services can be located precisely according to users’requirements and can be composed to handle the problem of composition. There are many ongoing studies and research projects on applications of Semantic Web technologies to Web services that provide automatic service discovery, service composition, and service execution. In this thesis, our objective is twofold: (1) implement a customized system that applies Semantic Web technologies to Web services and (2) dynamically synthesize existing services on the World Wide Web in order to fulfill the user''s needs. The architecture of the application system is built on an ontology that is defined by Web Ontology Language (OWL) for a specific domain. Service interfaces containing the necessary information for invoking a service are described by Web Service Description Language (WSDL). Since the user''s requirements are often ambiguous, automatic service matching with subsumption reasoning based on Description Logics (DLs) is a basic task. We also use Semantic Web Rule Language (SWRL) to increase the expressive power of concepts when describing complicated relationships between concepts. The composition of Web services is the most important aspect in Semantic Web services. We consider service composition in terms of logic theory and collate several composition patterns encountered in the real world. After composition, the services can be invoked and executed in the subsequent task. The execution process flows in terms of the execution order and interaction between Web services are defined by Business Process Execution Language for Web Service (BPEL4WS). Moreover, we propose a service execution module that provides a prototype of implementing service execution. We extend the execution fuction to a prototype system “the Traveller” that aims to help users discover, combine, and invoke the desired Web services for the tourism domain. We believe this thesis will be useful for explaining the automatic composition and execution of Web services, as well as providing examples of application of Semantic Web technologies.