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Querying Semistructured (Meta)data and Schemas on the Web: The case of RDF&RDFS

From: Greg Karvounarakis <gregkar@csi.forth.gr>
Date: Fri, 25 Feb 2000 17:34:21 +0200 (EET)
To: www-rdf-interest@w3.org
Message-ID: <Pine.GSO.4.10.10002251714110.6699-100000@crete.csi.forth.gr>

As a part of our work on RDF, we have produced a technical report on
querying RDF Metadata and Schemas.

You can reach it online (in PDF format) at:


A short abstract follows:

The need for descriptive information, i.e. metadata, about Web
resources has been recognized in several application contexts (e.g.,
digital libraries, infomediaries, portals, etc.). The Resource
Description Framework (RDF) aims at facilitating metadata creation and
exchange. In particular, the definition of schema vocabularies enables
the interpretation of RDF descriptions across several communities.
Unfortunately, existing RDF-enabled systems (e.g. browsers, search
engines) totally ignore schemas for metadata manipulation. In this
paper, we propose RQL, a declarative language suitable for querying
both RDF descriptions and schemas. RQL relies on a graph data model
capturing the RDF modeling primitives in terms of classes and
relationship types, organized into subsumption taxonomies.
Furthermore, a graph instantiation mechanism is introduced to
interpret semistructured RDF data using schema information.
Taxonomies of labels are then exploited transparently in order to
facilitate querying of complex semistructured data as well as of the
schema vocabularies themselves. To the best of our knowledge RQL is
the first language offering this functionality.

Greg Karvounarakis
Received on Friday, 25 February 2000 10:41:24 UTC

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