Optimizing Technology Research Of LazyDFA-based For XML Stream Query

With the wide application of Internet, some new concentrated data have approved, Which has made that stream data processing causes wide interest. Such as financial analysis, sensor network, network monitor and web usage log etc, those data stream processing and related technology have come to high attention recently, whose feature is that data is reaching quickly in the form of a continuous data stream in uncontrollable order on line and can not be stored, but queries are stored lastingly. This type of data stream application has produced some new problems. So the theory and technology about the XML data stream management and query have become the hot research in the field of data stream currently.XML data stream processing system is running on the Internet. The users are massive in this environment. They use XPath expression to describe their queries needs. How to process a large number of XPath queries on the XML data stream is an urgent problem need to be resolved in the application of data stream. This is the emphasis of this paper.This paper adopts automation and index technology to resolve data stream processing based XPath query. XPath expressions can be changed into automation machine according to XPath syntax rules and automation machine theory. Data structure of NFA and LazyDFA is designed to realize the query processing on XML data stream. After analyzing and researching the current methods and mechanisms of LazyDFA to resolve the query processing on XML data stream, optimization algorithms of constructing SIX for XML stream on XML data stream generator is given in order to improve the efficiency. Incremental query of data stream based LazyDFA is researched with SIX technologies. In theory the incremental query algorithm can improve the execution efficiency of the automation machine. Finally, experiment results show that LazyDFA can solve the problem of XPath query on XML data stream effectively and optimization algorithm can improve the execution efficiency of the automation LazyDFA.