Research On XML-based OWL Ontology Query Methed

Semantic Web was proposed by Tim Berners-Lee who invented Web in1998, and it would be an extension of today’s web. Information in the Semantic Web has well-dfined meaning, so computers could understand the messages, consequently the cooperation between people and computers would become very well. Semantic Web would adopt multiple-layered framework. XML lies in the second layer of Semantic Web framework, is the representation language of semantic Web. As a data structure defined in an open and self-describing way, XML can make document structured, describe both the content and structure of data, has the feature of scalability, structuralization, cross-platform and so on. Ontology layer is the turn of document depict and knowledge reasoning, so Ontology, which is the intelligence basis of computers to understand the information, has been a focus of research in recent years. Ontology is thought as the core technology to the realization of Semanic web. With the development of Semantic Web, a large of Ontology emerged. In order let Ontology, which is the carrier of the message, goes from the laboratory into practical applications, it is a hot research area how to effectively query the rich information in OWL Ontology, especially entailment information.In the query process of OWL Ontology, there are three issues need to consider. First is how to store OWL Ontology information. Second is how to ensure the accuracy and completeness of the Ontology query. Third is how to express the user’s query request. Based on these three issues and study on the present research and technology of OWL Ontology query, this paper presents a method of XML based OWL Query.The core content of the method proposed by this paper is:firstly, this method stores the information of OWL Ontology using XML document; secondly, this method use description logic reasoner to extract OWL Ontology information, generating the XML knowledge base. On this basis, running the reasoning and query algorithms of Tbox and Abox, to ensure the accuracy and completeness of Ontology query; thirdly, the use of nRQL, this specialized query language for OWL Ontology can be fully expressed the user’s query request. According to the proposed method, the paper design the algorithms of XML based OWL Ontology query, including algorithm of generating XML knowledge base and algortithm of reasoning and query based on XML knowledge base, and gives examples of the algorithm. Finally, to verify the proposed method, this paper designs an experimental system of XML-based OWL Ontology query. The design of the system takes the needs of Ontology query application into account, with a strong operational, versatility, portability and scalability. Experiments show that the proposed XML based OWL Ontology query method is feasible, and comparing with the existing OWL Ontology query system, the proposed method has the advantage of the query response time and the completeness.