Research On The XML Document Processing Based On Automata

XML is released as a markup language by W3C in 1998. As a result of its unique technique advantage, XML rapidly becomes the standard of data representation and exchange on the Web. Therefore, for building up various applications based on XML, it is initially important to accurately and effectively query/capture data from XML data source. On the basis of the automata technique, this paper discusses the effective validation of XQuery document and XML query optimization by both theory and experiments.With the focus on the problem of effective validation of the XQuery document, we make a comparative analysis between several XML Schema type validation approaches, and choose a type validation approach based on tree automata to deeply study. After finding out the limitation of the algorithm when processing an XQuery document (such a data structure that have embedded complex type), we propose a improved algorithm, then analyze the correctness and complexity of the improved algorithm.With the focus on deficiency of the current XML query optimization researches, we present an effective query optimization. The optimization consists of two key technologies: For the redundancy nodes in XML tree-pattern queries, we present an effective tree-pattern query optimization. Whether there are integrity constraints or not, the tree-pattern queries and the query expressions are minimized. On the basis of above researches, we utilize the XML partial query rewriting technique based on views to realize the XML document query optimization.At last, we design and realize an XML document processing system. According to the essential idea of XML validation and query optimization technique presented above, we analyze and design the architecture of the system. The system first processes effective validation to the XQuery document that user submits, then implements the optimization processing with the query optimization in this paper, finally carries it out and gets results. Moreover, the paper also presents two scenarios to test the system. It's verified from the experiment results that the new query optimization method presented in this paper can highly improve the XML query efficiency.