The Research About XML In Application Of Data Query

With the development of internet technology, research on XML has been made great progress. Different from HTML, XML separates information contents from information rendering. It has strong ability of describing itself and good extensibility. These characters facilitate the information sharing and query on the web. Now it has been applied to all kinds of applications, including industry data standard definition, electronic data exchange and integratiion. XML is now on the way to be a new standard for data representation and exchange.First, this thesis analyses the schema of XML data and document, researches several main XML Schemas : DTD, W3C Schema and Relax NG through comparing method because xml schema languages exist in kind of types with different features and advantages. Second, this thesis discusses several key technologies of operating xml data, including Data Source Objects and two main API: Document Object Model and Simple APIs for XML. These several technologies take important role in the integration system of the traditional database and XML, data query is always fulfilled based on them. This thesis emphasizes on the XML data model and its query arithmetic. At the database point, XML document is a typical semi-structured data set: it is irregular ,incomplete, and unstable. it is self-describing. XML can be modeled as a tree that the tags define tree node and the leaves are the data value. Therefore, according to the structure of XML document , the thesis advaces the path query arithmetic and tree query arithmetic. The thesis...