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

D2R MAP - Database to RDF Mapping Language and Processor

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:


  • 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.

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.

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.


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:


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

RDF project description



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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