| The new requirement is raised for data management and analysis in the new application areas such as Sensor data processing, data processing in negotiable securities managing, flux in internet monitoring, web usage log etc, data stream and related technology have come to high attention at present. XML has become the de facto standard for data representation and exchange on the web. In the recent years, it is widely applied in the emerging application systems, such as Web services and personalized content delivery. In these applications, XML data arrived quickly in the form of a continuous data stream. So the theory and technology about the management and analysis of XML data stream have become the hot research in the field of data stream currently.With the further application of XML, the XML data stream which has different depths of recursion wildly appeared. When the XPath which includes the'//'axis and predicates query it, the multiple matching will happen and a lot of matching modules will generate. The traditional method mainly focuses attention on a large number of queries on the XML data stream, which doesn't meet the present need, so how to complete the recursive query over XML data stream is an urgent problem.In this paper we merge the features of XML data stream processing, analysis and research the current methods and mechanisms to resolve the query processing on XML data stream. Based on XPath syntax rules, an arbitrary path of an XPath expressions can be transformed into context-free grammar, and according to the automata theory, a method based on pushdown automation is introduced. It make the kinds of XPath steps transform into the processing modules, by which the top-down tree query model is built, the method successfully completed the recursive query over XML data stream.Finally, experimental results show that this method can solve the problem of recursion query on XML data stream effectively, and the proposed method is better than the traditional method. |
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