| Integrated Query Processing over Autonomous Heterogeneous Data SourcesLi Xiao Dong(Computer Application Technologies)Directed By YuQing GuThe requirements of integrating multiple data sources exist for a long time. The research on data integration system is always very active in database community and other related communities. The Web is becoming a major conduit for people to obtain information, so the research on data integration under Web environment is very flourishing in recent years.The paper primarily contains five parts:At first, we put forward an XML data model named XTree. Based on the model, the author designed a novel XML query language called AnXQL. The AnXQL had powerful expressions with simple constructs and precise semantics. Secondly, we made use of views on mediated schema to describe the content of data sources. Then we novelly adopt 'answering queries using views' technique into XML query reformulations. The mechanism can express fine-grained differences between data sources. The author also developed an algorithm which reformulate user's query on mediated schema into subqueries that refered directly to the schemas of the sources. Thirdly, an algebra was proposed for XML query. The paper addressed algebra rewriting-based optimization techniques. At the same time, the author quantified the complex degree of XML data to assist the optimization of queries with regular path expressions.Fourthly, the paper designed a novel and lightweight approach to translate XML queries into SQL and transform the retured tuples into XML representation A wrapper for relational sources was developed based on the approach. Based on DOM and inductive learning, the paper also present a novel approach to semi-automatically generate Java classes which can be dominant part of a wrapper for Web sources.Finally, the author proposed a declarative web page definition language. The language can faciliate maintainment, restructuring, reusability of data-intensive Web sites.
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