Xml-based Web Query

WWW is the most widely used information service system on the Internet. It offers a TDO! to search and browse information. But WWW contains too much information and billions of pages located on thousands of servers in different palaces in the world. Every server manages its own resources, and does not follow one standard managing mechanics. In general, there are wealthy of various resources on the net, which can not be shared and queried effectively. The emergence of XML provides a resolution to the above-mentioned problem. The full name of XML is Extensible Markup Language. It is a simplified and restricted subset of SGML, particularly devised for Web application. XML is an excellent tool for data exchange on the internet.Due to its capability to combine structured data with different sources, XML makes it possible to retrieve data from different and incompatible database servers, and brings hopes for Web data query. This article focus on these following problems:1. Consicering the big difference of data format and data sources on the Web, We made research and discuss on the Web data model梄ML data model.2. To resolve the problem of integration'of data with different structure. Because the integration problem mainly focus on the integration of different structured RDBMS, this article adopted mediated schema and transformed the data in RDBMS into XML data source. Therefore, better sharing of data can be realized.3. Making full use of the advantages of using XML data model in semi-structured data representation and query, we can carry out data retrieving queries from XML data resources on Web by using XML-QL.Before the emergence of XML, Web-oriented data query is a complex technique. Through the research in this article, if we represent Web data by XML data model and transform the structured data from different data source into XML data format sources, we will realize data sharing and carry out exact and efficient data query, which will simplify our work and enhance efficiency greatly.