Querying XML documents in logic programming

Abstract

AbstractExtensible Markup Language (XML)is a simple, very flexible text format derived from SGML. Originally designed to meet the challenges of large-scale electronic publishing, XML is also playing an increasingly important role in the exchange of a wide variety of data on the Web and elsewhere.XPathlanguage is the result of an effort to provide address parts of an XML document. In support of this primary purpose, it becomes in aquery languageagainst an XML document. In this paper we present a proposal for the implementation of theXPathlanguage in logic programming. With this aim we will describe the representation of XML documents by means of alogic program.Rulesandfactscan be used for representing the document schema and the XML document itself. In particular, we will presenthow to index XML documentsin logic programs: rules are supposed to be stored inmain memory, however facts are stored insecondary memoryby using two kind of indexes: one for each XML tag, and other for each group of terminal items. In addition, we will study how to query by means of theXPathlanguage against a logic program representing an XML document. It evolves thespecialization of the logic programwith regard to theXPathexpression. Finally, we will also explain how tocombine the indexing and the top-down evaluationof the logic program.