Article,
The syntactic web
Markup Lang., 3 (4): 411--440 (2001)
DOI: http://dx.doi.org/10.1162/109966202760152176
Abstract
XQuery is a query language designed to allow queries across the many kinds of
information that are represented in XML. Although topic maps and RDF can
also be represented in XML, many have held that their many possible syntactic
forms make them extremely difficult to query using an XML query language,
and that they can only be queried using special-purpose query languages with
built-in knowledge of their semantics, including the ability to exploit RDF schema
information. This talk shows that XQuery can, in fact, be used to solve the kinds
of queries for which RDF and topic map query languages were designed, though
with a loss of type safety.
The approach taken is to transform instances of RDF and topic maps to a syntactic
representation that closely models their underlying logical models, and to use
function libraries written in XQuery to directly support operations specific to
RDF or topic maps. Schema level information is also incorporated in this repres-
entation, and is supported in the library, so queries can exploit type hierarchies
and perform joins across predicates.
Information from other XML sources can also be queried together with inform-
ation from topic maps and RDF. For instance, a query on a topic maps that
searches for Shakespeare plays mentioned in Italian operas can also query the
plays themselves -- represented in XML -- to determine which Italian cities are
mentioned in them.
Syntax is not the opposite of semantics, it is a medium for semantics.
