W3C Technology and Society Domain The Semantic Web Home Page

- Call For Participation -

W3C Workshop on
RDF Access to Relational Databases

25-26 October, 2007 — Boston, MA, USA

Summary: Systems for exporting relational data to RDF have existed since the beginning of the Semantic Web. Recently, the Semantic Web developers have focused on SPARQL query-rewriters and interpreters to access relational data directly. Both of these approaches share an expression of relational data in RDF. This workshop will draw members of the Semantic Web and relational database communities together to examine commonalities, distinctions and next steps for expressing relational data in RDF.

The ubiquity of relational data makes it an attractive next target for the Semantic Web. Much of the data that is used in automation is stored in relational databases. RDF's grounding in universal terms makes RDF attractive to the relational database community. Expressing relational data in RDF allows them to join relational data with data in other databases or in other forms.

This workshop, held by W3C and hosted by Novartis, focuses on RDF access to existing relational data. We will discuss querying, update and expressing in a form consistent with Web Architecture. Consumers and potential consumers of RDF data will provide use cases and goals.

See workshop site for news and repository of contributed materials




Ubiquity of relational data

Relational data expresses a large fraction of the coded human knowledge. SQL is used constantly to access a huge range of scales of data, from personal music collections to reservation systems and inventory lists for multinational corporations. Access to this structured data can increase the size and utility of the Semantic Web many times over.

Despite the ubiquity and utility of relational data, connecting data between databases remains problematic and resource-intensive. Joining data between independently-developed relational databases requires tedious scripting, data warehousing, or tailored integration systems. RDF queries accessing multiple relational databases have shown that RDF can be used to unify independent relational databases and link in external sources, e.g. documents and data from the Web.

The provenance for relational data in the RDF can also be expressed in RDF. All of this data will be available for access by query and rules languages.


In several deployed systems, the tuples in a relation are identified by a URL composed of table name and primary key attributes/value pairs. This provides the subject of a set of triples, each expressing the attributes of that tuple. For these, the predicate is composed of table name and the attribute name. The objects are literals to express simple relational attributes and URI references to express foreign key relationships to other tuples. Foreign keys to multiple other tuples are simple expressed as repeated attributes.

Current Work

Please check out the following work on mapping relational data to RDF:

D2RQ V0.5 - Treating Non-RDF Relational Databases as Virtual RDF Graphs , Chris Bizer, Richard Cyganiak, Jörg Garbers, Oliver Maresch, Editors, 01 November 2006, http://www.wiwiss.fu-berlin.de/suhl/bizer/d2rq/spec/20061030/ . Latest version available at http://www.wiwiss.fu-berlin.de/suhl/bizer/d2rq/spec/ .
DartGrid , http://ccnt.zju.edu.cn/projects/dartgrid/ . Documentation available at http://ccnt.zju.edu.cn/projects/dartgrid/document.html .
RDF/RDFS-based Relational Database Integration , Huajun Chen, Zhaohui Wu, Heng Wang, Yuxin Mao, 2006, http://doi.ieeecomputersociety.org/10.1109/ICDE.2006.127 .
Mapping Relational Data to RDF in Virtuoso , Orri Erling, Ivan Mikhailov, 2006, http://virtuoso.openlinksw.com/wiki/main/Main/VOSSQLRDF .
Relational Databases on the Semantic Web , Tim Berners-Lee, 2006, http://www.w3.org/DesignIssues/RDB-RDF .
RDF Access to Relational Databases , Eric Prud'hommeaus, Jan 2003, http://www.w3.org/2003/01/21-RDF-RDB-access/ .

Workshop Goals

The specific goals for this workshop are:

  1. Gather and refine use cases and requirements for a framework;
  2. Gather information about available technologies and relevant areas of practice and research;
  3. Help establish a common ground for this work as well as a community of possible participants;
  4. Understand priorities and time frames and gather information to establish a strategy and a calendar;
  5. Help organizations and individuals learn enough about this work to determine their level of commitment going forward.


The workshop is expected to result in the following deliverables:

These will be published on the workshop home page.

Scope of the Workshop

The scope of this workshop is restricted in order to make the best use of participants' time. In general, discussion at the workshop and in the position papers should stay focused on the workshop goals and deliverables.

In scope:

Out of scope:


Expected Audience

We expect several communities to contribute to the workshop:

Requirements for Participation

Position Papers

Position papers are the basis for the discussion at the workshop. These papers will also be made available to the public from the workshop site.



All papers should be 1 to 5 pages, although they may link to longer versions or appendixes. Papers should explain the participant's interest in the workshop, explain their position with respect to a standard for expressing relational data as RDF.

Accepted position papers will be published on the public Web pages of the workshop. Submitting a position paper comprises a default recognition of these terms for publication. Allowed formats are (valid) HTML/XHTML, PDF, or plain text. Papers in any other formats (including invalid HTML/XHTML) will be returned with a request for correct formatting. Good examples of position papers can be seen in the QL'98 workshop.

The Program Committee may ask the authors of particularly salient position papers to explicitly present their position at the workshop to foster discussion. Presenters will be asked to make the slides of the presentation available on the workshop home page in HTML, PDF, or plain text.

Position papers must be submitted via email to RdfRDB-chairs@w3.org no later than 10 September 2007. Early submissions are appreciated.

Workshop Organization

Workshop Chairs

W3C team contact: Eric Prud'hommeaux

Program Committee

At this time, the program committee is still being assembled. The list so far:




The workshop program will run from 8:30 am to 6 pm on both days.


The workshop will be held at:

250 Massachusetts Ave,
Cambridge, MA 02139, USA

Important Dates

Date Event
20 July 2007 Call For Participation issued
10 September Deadline for position papers.
20 September Acceptance notification sent; Program released
around 15 October Deadline for registration
25 October Workshop Begins (8:30 AM)
26 October Workshop Ends (6 PM)

Eric Prud'hommeaux,
$Id: cfp.html,v 1.26 2007/11/18 03:43:03 eric Exp $