LazyDFA Based Query Processing And Optimized Technology Research On The XML Data Stream

As the new application areas raise new requirement for data management and analysis, such as data processing in negotiable securities managing,flux in internet monitoring,web usage log etc,data stream and related technology have come to high attention recently.There has been a large number of XML data stream related applications such as content-based routing of XML,Web services,subscription and publishing system of active services etc with XML language has become an important criteria of the information representation and data exchange on the Internet.In these applications,XML data arrived quickly in the form of a continuous data stream.So the theory and technology about the XML data stream management and analysis have become the hot research in the field of data stream currently.XML data stream processing systems are running on the Internet, and the users are massive in this environment.The massive users use XPath queries to describe their needs, then how to process a large number of queries on the XML data stream is a urgent problem need to solve in the application of data stream.So we put the emphases on it.In this paper we creat the automaton machine,design its data structure,realize the query processing on XML data stream and give five optimized algorithms in order to improve the efficiency .In this process,we merge the features of XMI data stream processing such as each node in XML can only visit once, processing algorithm has the smallest possible space complexity, and each node must have a high treatment efficiency of the time to meet the needs of real-time processing etc, analysis and research the current methods and mechanisms to resolve the query processing on XML data stream,ground XPath syntax rules which is arbitrary path of a XPath expressions can be transformed into a regular expression,and use the automata theory to create NFA and lazyDFA,which realisze the query processing of XPath expressions and present five optimized algorithms which are shared prefixable path,shared NFA state table,creating state-transfer table,based on semantic and constructional information of DTD aiming at improving the execution efficiency of the automaton machine.Finally,experimental results show that this method can solve the problem of query on XML data stream effectively, and optimized algorithms can improve the operating efficiency of the automaton machine.