On a Declarative Semantics for Web Queries

Rainer Himmeröder, Bertram Ludäscher
Abstract. Languages supporting deduction and object-orientation are particularly suited for querying and reasoning about the Web structure and the contents of semistructured (Web) documents. We show how FLORID, an implementation of the deductive object-oriented query language F-Logic, can be extended to provide a declarative semantics for querying Web documents. The proposed extension allows extraction and restructuring of data from the Web and a seamless integration with local data. Due to a simple yet powerful predicate for matching regular expressions, and the (meta-)features of F-logic including path expressions, separate languages for wrappers and mediators become superfluous in our approach. The concise, declarative programming style is illustrated with a comprehensive example.