D2R Map - Database to RDF Map

Fachbereich Wirtschaftswissenschaft - Freie Universität Berlin
Chris Bizer - Institut für Produktion, Wirtschaftsinformatik und OR

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D2R MAP - Database to RDF Mapping Language and Processor

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D2R MAP is a declarative language to describe mappings between relational database schemata and OWL/RDFS ontologies. The mappings can be used by a D2R processor to export data from a relational database into RDF.

For details about D2R MAP see:

D2R language specification.pdf and D2R Map.dtd
Poster and Paper "D2R MAP - A Database to RDF Mapping Language", presented at WWW2003

News

18.10.2005: There is a new D2RQ mailing list: d2rq-map-devel. Please direct questions about D2R Map also to this list.
5.4.2005: Jimmy Cerra has extended D2R's URI construction patterns with lots of useful new functions. The extended version of D2R MAP can be downloaded from https://nemo.dev.java.net/servlets/ProjectDocumentList?folderID=3019
23.7.2004: D2R Map Version 0.3 has been released. The new release supports different Jena model implementations like the Kowari Metastore. ProcessMap methods, connection and driver accessors have been added to the D2R processor. The error handling has changed to Log4J and Ant build scripts have been added. Thanks a lot to Robert Turner from Tucana Technologies for his contributions.
3.5.2004: There is ongoing work on D2RQ. D2RQ can be used to rewrite RDQL queries to SQL queries against non-RDF databases. The goal is to allow the usage of Semantic Web query languages for querying existing legacy databases. See D2RQ for details.
29.9.2003: D2R Map Version 0.2 has been released. The new release is based on Jena 2 and we have added an connector for using D2R MAP within the Joseki RDF server. Thanks a lot to Andy Seaborne from HP Labs for his support.

The Mapping Process

The mapping process executed by the D2R processor has four logical steps:

1. Selection of a record set from the database using SQL
2. Grouping of the record set by the d2r:groupBy columns.
3. Creation of class instances and identifier construction.
4. Mapping of the grouped record set data to instance properties.

D2R Processor Prototype

A prototypical implementation of a D2R processor is available under GNU Lesser General Public Licence (LGPL). The processor is implemented in Java and is based on the Jena framework. It exports data as RDF, N3, N-TRIPLES and Jena models.

The processor can be used

as command line tool to export the content of a relational database into RDF,
in an servlet environment to dynamically publish XHTML pages containing RDF,
as database connector in applications working with Jena models.

Download the processor prototype ...
View Javadoc documentation ...

D2R Examples

Example 1: CD Shop

This example shows, how a simple D2R Map is used to export data about CDs, tracks and music categories from a MS Access database to RDF.

D2R map: eShopMap.d2r.xml
Example database (with some entries from ISWC 2002)

Microsoft Access database:eShop.mdb
MySQL database dump:eShop.sql.txt

Output created by the processor prototype:

Standard RDF: output-cd-example.rdf.xmll
RDF/XML-ABBREV: output-cd-example.rdf-abbrev.xml
N3: output-cd-example.n3.txt
N-TRIPLE: output-cd-example.n-triple.txt

Example 2: Conference

This example shows, how a D2R Map is used to export data about Persons, Organizations, Research Topics and Papers from a MS Access database to the ISWC ontology.

D2R map: iswcMap.d2r.xml
ISWC ontology: ISWC.daml.xml
Example database (with some entries from ISWC 2002):

Microsoft Access database:ISWC.mdb
MySQL database dump:iswc.sql.txt

Output created by the processor prototype:

Standard RDF: output.rdf.xml
RDF/XML-ABBREV: output.rdf-ABBREV.xml
N3: output.N3.txt
N-TRIPLE: output.N-TRIPLE.txt

Example 3: Timetabling (by Peter Demeester, Belgium)

This example from the CoFfTeA project shows, how a D2R Map is used to export data about sessions, timeslots, attendees and locations from a MS SQL Server database to a timetabling ontology.

D2R map: hybrid_last.d2r.xml
Timetabling Ontology: hybrid.daml

References

Dave Beckett, Jan Grant: SWAD-Europe: Mapping Semantic Web Data with RDBMSes. January 2003: A public report on mapping triple stores and RDBMS.
Tim Berners-Lee: Relational Databases on the Semantic Web. March 2002.
Gert Pache: KAON - REVERSE: Mapping toolset and editor, AIFB, Karlsruhe University, Germany.
Ronald Bourret: XML-DBMS. Interesting bidirectional mapping language for transferring data between XML documents and relational databases.
Vipul Kashyap: The Semantic Web: Has the DB Community missed the bus (again)? April, 2002.
Amit Sheth, Robert Meersman: Database and Information Systems Research Challenges and Opportunities in Semantic Web and Enterprises. Workshop Report, December 2002.
Eric Prud'hommeaux: Persistent RDF Databases.
For a genaral overview about other RDF resources and tools see: Dave Beckett's Resource Description Framework (RDF) Resource Guide
Our other open source projects @ Freie Universität Berlin

Mailing List

We are very interested in hearing about your experiences with D2R MAP, its performance with different databases, bugs and ideas for further language extensions.

Please sent your comments to the D2R MAP and D2RQ mailing list:

d2rq-map-devel@lists.sourceforge.net

The archives of the list are found at: http://sourceforge.net/mailarchive/forum.php?forum=d2rq-map-devel
You can subscribe to the list at: http://lists.sourceforge.net/lists/listinfo/d2rq-map-devel

Chris Bizer
homepage:www.bizer.de
mailto:chris@bizer.de

RDF project description

D2RMAP.rdf.xml

Freie Universität Berlin - Fachbereich Wirtschaftswissenschaft - Institut für Produktion, Wirtschaftsinformatik und Operations Research
Lehrstuhl für Wirtschaftsinformatik: Prof. Dr. Uwe H. Suhl
Letzte Aktualisierung: 16.10.2006
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