Evaluating Linear XPath Expressions by Pattern-Matching Automata

: We consider the problem of efficiently evaluating a large number of XPath expressions, especially in the case when they define subscriber profiles for filtering of XML documents. For each document in an XML document stream, the task is to determine those profiles that match the document. In this article we present a new general method for filtering with profiles expressed by linear XPath expressions with child operators (/), descendant operators (//), and wildcards (∗). This new filtering algorithm is based on a backtracking deterministic finite automaton derived from the classic Aho–Corasick pattern-matching automaton. This automaton has a size linear in the sum of the sizes of the XPath filters, and the worst-case time bound of the algorithm is much less than the time bound of the simulation of linear-size nondeterministic automata. Our new algorithm has a predecessor that can handle child and descendant operators but not wildcards, and has been shown to be extremely e...

• Type: Journal
• Year: 2010
• Where: JUCS
• Authors: Panu Silvasti, Seppo Sippu, Eljas Soisalon-Soininen
• Keywords: JUCS 2010, Wildcards, XML Documents, XPath Expressions