RQL: A Declarative Query Language for RDF
Proceedings of the eleventh international conference on World Wide
Web, page 592-603. (2002)Abstract
Real scale Semantic Web applications such as Web Portals and
E Marketplaces re quire the management of voluminous metadata
repositories containing descriptive infor mation i e metadata about
the available Web resources and services Better knowledge about
the meaning usage accessibility or quality of these resources and
services will con siderably facilitate the automated processing of
both Web content and services In this context the Resource
Description Framework RDF enables the creation and exchange
of metadata as any other Web data Although large volumes of RDF
descriptions are already appearing e g as exported Portal catalogs
or service descriptions su ciently expressive declarative languages
for querying both RDF descriptions and schemas are still missing
In this paper we propose RQL a new RDF query language relying
on a formal graph model that permits the interpretation of superimposed
resource descriptions RQL is an OQL inspired adaptation of XML
query languages to the peculiarities of RDF but foremost is an
extension of this functionality for uniformly querying both descriptions
and schemas We illustrate the syntax semantics and core functionality
of RQL by means of a set of benchmark queries and report on the
performance of RSSDB our persistent RDF Store for storing and
querying voluminous RDF descriptions
