Research On XML Data Theory Based On Probability

With the comprehensive application of semi-structured probabilistic data, the research on the semi-structured probabilistic data management theory is essential.Because the XML data is a new data formal of network application and is the data interchange and the data representation standard on the Internet,the research on XML data management theory based on probability management theory has the theory research significance and the application impor-tance.Aiming at the management problem of probabilistic XML data, the research on the problems of the probabilistic data representation methods in the XML data, the research on data transformation problem between the probabilistic relation data and the probabilistic XML data, the design of the query algebra operation set, extending the Xquery function to query probabilistic XML data implementation, and the element node probability query problem are systemic and embedded.The probabilistic data based on relation is a classical probabilistic data formal, so the research on data transformation problem between the probabilistic relation data and the probabilistic XML data is essential. As XML data tree and XML data graph are two kinds of common XML data models, the XML data based on probability is denoted and the bidirectional transformation algorithm is represented between probabilistic data based on relation and XML.The algorithm is composed of two steps. The first step is the schema transformation procedure. And the second step is data transformation procedure. Based on the studied transformation strategy,the bidirectional probabilistic data schema transformation algorithms which convert probabilistic relation schema to probabilistic XML schema PDTD and convert probabilistic XML schema PDTD to probabilistic relation schema are proposed.The bidirectional probabilistic data transformation algorithms which convert probabilistic relation schema to probabilistic XML data and convert probabilistic XML data to probabilistic relation data are proposed. By theory analysis, it proves that the algorithms are right and self-contained. And it proves that they are right through the instances.The design of the query algebra operation set is the basic method of the probabilistic XML data query and query optimization, so the basic operation set of probabilistic XML data following the probabilistic XML data tree. In the basic operation set the basic operation unit is probabilistic XML unit tree whose schema is probabilistic XML unit schema tree. The algorithms of basic operation set based on the parsed path expression set are presented. By theory analysis, it proves that the algorithms are right and self-contained. And it proves that they are right through the instances.As Xquery is an effective XML query language, extending the Xquery function is an easy kind of query probabilistic XML data implementation method in order to support the probabilistic XML data query problem. The probabilistic function eXquery for the extended XML query language Xquery function set is presented. According to the function class of Xquery function set, the functions such as functions related with probabilistic XML tree types, path expression and node operation are designed.As the element node probability query problem is one of the main contents of probabilistic XML data query, so research on the element node probability of query algorithm in the probabilistic XML data tree is also necessary. Based on the analysis of query strategy, the two kinds of methods are presented. One is based on possible world model, the other is based on the parsed path expression set. During the course of the theory analysis, the algorithms are proved right and self-contained. It also proves that they are right through the instances and analyzed the applicability of probabilistic XML data tree size.