With the internet development, querying data on the Web is an attention problem of involving information from distributed, and often dynamically, related Web sources. Basically, some subqueries can be effectively cach...With the internet development, querying data on the Web is an attention problem of involving information from distributed, and often dynamically, related Web sources. Basically, some subqueries can be effectively cached from previous queries or materialized views in order to achieve a better query performance based on the notion of rewriting queries. In this paper, we propose a novel query-rewriting model, called Hierarchical Query Tree, for representing Web queries. Hierarchical Query Tree is a labeled tree that is suit able for representing the inherent hierarchy feature of data on the Web. Based on Hierarchical Query Tree, we use case based approach to determine what the query results should be. The definitions of queries and query results are both re presented as labeled trees. Thus, we can use the same model for representing cases and the medium query results can also be dynamically updated by the user queries. We show that our case-based method can be used to answer a new query based on the combination of previous queries, including changes of requirements and various information sources.展开更多
To enable accessing web information at semantic level, this paper develops a semantic query rewriting mechanism on peer to peer XISs with complex ontology mapping technology. It discusses the patterns of complex ontol...To enable accessing web information at semantic level, this paper develops a semantic query rewriting mechanism on peer to peer XISs with complex ontology mapping technology. It discusses the patterns of complex ontology mappings at first, and the ontology-based query mechanism in peer to peer environment. The extension of XML query algebra and XML query rewriting mechanism are dissussed in detail.展开更多
基金Supported by the National Natural Science Funda-tion of China (60473074) and Natural Science Foundationfor DoctoralCareer Award of Liaoning Province (20041016)
文摘With the internet development, querying data on the Web is an attention problem of involving information from distributed, and often dynamically, related Web sources. Basically, some subqueries can be effectively cached from previous queries or materialized views in order to achieve a better query performance based on the notion of rewriting queries. In this paper, we propose a novel query-rewriting model, called Hierarchical Query Tree, for representing Web queries. Hierarchical Query Tree is a labeled tree that is suit able for representing the inherent hierarchy feature of data on the Web. Based on Hierarchical Query Tree, we use case based approach to determine what the query results should be. The definitions of queries and query results are both re presented as labeled trees. Thus, we can use the same model for representing cases and the medium query results can also be dynamically updated by the user queries. We show that our case-based method can be used to answer a new query based on the combination of previous queries, including changes of requirements and various information sources.
基金Supported by the Natural Science Foundation ofHubei Province(2005ABA235) Key Project of Science Research ofEducation Agency of Hubei Province (Z200511005)
文摘To enable accessing web information at semantic level, this paper develops a semantic query rewriting mechanism on peer to peer XISs with complex ontology mapping technology. It discusses the patterns of complex ontology mappings at first, and the ontology-based query mechanism in peer to peer environment. The extension of XML query algebra and XML query rewriting mechanism are dissussed in detail.
