Browsing by Author "Mengchi LIU"

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    XTree: A Declarative Query Language for XML Documents
    (2005-01-11T07:45:30Z) Zhuo CHEN; Tok Wang LING; Mengchi LIU; Gillian DOBBIE
    XML is becoming prevalent in data presentation and data exchange on the internet. One important issue in the XML research community is how to query XML documents to extract and restructure information. Currently, XQuery based on XPath is the most promising standard. In this paper, we discuss limitations of XPath and XQuery, and propose a generalization of XPath called XTree that overcomes these limitations. Using XTree, multiple variable bindings can be instantiated in one expression; and XTree expressions, which represent a tree rather than a path, can be used in both the querying part and the result construction part of a query. Based on XTree, we develop an XTree query language, which is more compact and convenient to use than XQuery, and supports common query operations such as join, negation, grouping, and recursion in a direct way. We describe an algorithm that converts XTree query scripts to XQuery scripts. This algorithm provides not only a means of executing queries written in XTree query language but also highlights differences between the two query languages.