Research On XPath Query Model

At present, more and more data have been described, stored and exchanged by XML with the constant development of XML technology and the continuous extension of its applications. The study of XML Data Flow Query has become the focus of the field of XML technological study. Meanwhile, the users' queries are usually expressed by XPath language. When the XML data stream arrives, the query processing system, according to users'input of XPath query expression matching with the XML data stream, returns the match results in time. Under normal circumstances, the system needs to handle a large number of XPath queries from users; therefore, how to give back the users timely and efficient query results is a critical study of XML queries.This paper, by the analysis of the XPath query expression, notes this fact that lots of XPath query expressions have a certain degree of similarity and they may have the same predicate expression items. If we can reduce the calculation of the same predicate expression items, the query efficiency can be effectively improved. Based on this and combined with XML Stream Index, path query technique and so on, this paper presents new methods based on a stream index-based XPath query predicates; and designs and implements XPath query model to deal with predicate by using the approach to deal with the predicate.The main contributions as follows:1. the paper describes the research status of XML data stream query at home and abroad, and introduces the related technologies of XML, as well as In-depth study of several popular XPath query model. And the paper emphasizes on analyzing the automatic machine-based XPath query model.2. The paper gives the analysis of a common approach to predicate which is shared path-based, and proposes a stream index-based of the predicate approach. Besides, it gives basic idea of the initiative computation model, the model structure and the processing algorithm and introduces predicate processor handling mechanism and method of optimization.3. The paper designs and implements XPath query model using stream index-based of the predicate processing approach to deal with predicate expressions and analyzes the designing ideas of the model and model framework.4. That the Stream Index-based XPath query model can effectively improve the query efficiency has been proved through experiments, suitable to handle large documents and complex XPath queries...