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ANN: D2RQ Jena plug-in released for treating non-RDF databases as virtual RDF graphs

From: Chris Bizer <chris@bizer.de>
Date: Tue, 22 Jun 2004 14:18:10 +0200
Message-ID: <006e01c45852$fcc24850$0f8d2da0@wrz03295>
To: <www-rdf-interest@w3.org>
Cc: "Richard Cyganiak" <richard@cyganiak.de>, <wilkinson@hpl.hp.com>, <kers@hpl.hp.com>, "Seaborne, Andy" <Andy_Seaborne@hplb.hpl.hp.com>, <dwood@tucanatech.com>, "Krishnamurthy, Venkat" <Venkat.Krishnamurthy@gs.com>, "Leo Sauermann" <leo@gnowsis.com>, "Sunil Goyal" <sgoyal@salzburgresearch.at>, <nbi_wn@lists.spline.inf.fu-berlin.de>, "Uwe Suhl" <suhl@wiwiss.fu-berlin.de>

Hi all,

we released the initial version of the D2RQ Jena plug-in under General
Public License today.

D2RQ is a declarative mapping language for treating non-RDF databases as
virtual RDF graphs within the Jena toolkit.

Using D2RQ you can:

1. access information in a non-RDF database using the Jena model API.
2. query a non-RDF database using RDQL or find(spo).
3. do RDFS and OWL inferencing over the content of a non-RDF database using
the Jena ontology API.
4. publish the content of a non-RDF database on the Semantic Web using the
Joseki RDF server.

The goal of D2RQ is to expose the content of huge, live, non-RDF databases
to the Semantic Web without having to replicate the database into RDF.

D2RQ is implemented as a Jena graph, the basic information representation
object within the Jena framework. A D2RQ graph wraps one or more local
relational databases into a virtual, read-only RDF graph. It rewrites Jena
API calls, find() and RDQL queries to application-data-model specific SQL
queries. The result sets of these SQL queries are transformed into RDF
triples which are passed up to the higher layers of the Jena framework.

For more information about D2RQ see
1. the D2RQ User Manual and Language Specification:
2. the D2RQ Website:

The D2RQ Jena plug-in can be downloaded from:

Lots of thanks to
1. Andy Seaborne (HP Labs, Bristol), Chris Dollin (HP Labs, Bristol) and
Kevin Wilkinson (HP Labs, Palo Alto) for their feedback on the D2RQ language
2. Richard Cyganiak (FU Berlin) for helping to implement D2RQ and for
developing a performance test suite for D2RQ (results will be released


Chris Bizer
Received on Tuesday, 22 June 2004 08:18:07 UTC

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