The Xml Document Object Model Persistence In The Oscar And Query Translation

In recent years, with the development of Internet, XML has made great progress and applied in the fields of electronic business, network publication and mobile communication. It is emerged as a new standard for data representation and exchange under, especially, by the promotion of W3C and leading computer companies. Known from HTML, XML separates information contents from information rendering. This character facilitates the sharing and retrieval of information on the Web. From a database point of view, XML data is very different from any other traditional data. It is a typical semi-structured data set: it is irregular or incomplete, and its structure may change rapidly. From the application point of view, XML applications focus on data transformations, query translation, data transport and stream-based processing. How to combine XMIL and database system technologies seemly is a challenging task. A way is using the mapping from the DTD or schema of XML to database schema. But it may lose some useful information of XML documents, which is very important for document-centric applications. Other way is using Native XML Database technology. Native XML Database defines a logic model for an XML document and stores it. An XML document is its fundamental unit of logical storage, just as a row in a table is the one in a relaitonal database. The underlying physical storage model is not required. It can be built on a relational, hierarchical, and object-oriented database, or a proprietary storage format such as indexed, compressed files. We adopt Native XML Database technology and use Document Object Model as the logic model and store it in our database system OSCAR. The large document can benefit from it, because it may be aborted as the memory is too small to store the Tree-like structure while the parsing process. This dissertation is organized as follows: The first chapter describes the concepts of XML and the relative database technologies. The second chapter introduces Native XML Database technology. The third chapter presents one of Native XML Database solutions: persistent document object model. The fourth chapter discusses how to store document object model inOSCAR. The fifth chapter introduces the corresponding query translation. The sixth chapter gives a conclusion and the perspective.