Xml-based Data Exchange And Data Access Technology And Its Applications

Data resources are closely interconnected with the popularity of the Internet. Web has become the biggest information resource which contains data of various platforms or formats. How to efficiently exchange, access or query the data is one of the serious problems emerge these years. XML is regarded as the solution to this problem by the software industry. And with the standardization and widely applcation of XML, main vendors have been integrating XML into many products such as database engines, development tools, Internet browsers and operating systems etc. Many XML-based technologies has been invented and developed.XML is a self describing markup language with embedded document structure which makes the XML document is more verbose than other documents contain the same data. The size of the XML document will have an impact on the efficiency and scalability of the application. General compressing technologies are not proper in some circumstances for the receivers are always required to decompress the data completely to manupulate the original data (querying, validating etc.). The embedded document structure of XML also makes it difficult to perform access control because the traditional file level access control systems could not fulfill the requirement of element or attribute level access control.In the paper we first present a scheme for XML-based data exchange which is an XPath-query-friendly compressor for XML. It leverages the LZW algorithm and Huffman encoding, compressing the XML data on element and attribute level and separating the structure of the document from the content. We describe the architecture of the system, the design principles and the technologies used, and we also present the compress results in contrast with other compressors.Then we propose an XML data access control system which uses extended XPath and user or user group information to define the access object. We describe the architecture, the subject, object, access rules and the different levels of the rules. And we also illustrate the access control process with an example.Finally we conclude the thesis and list future work.