D2R Server provides SPARQL access to relational databases. The server takes SPARQL queries from the Web and rewrites them via a D2RQ mapping into SQL queries against a relational database. This on-the-fly translation allows RDF applications to access the content of large databases without having to replicate them into RDF. D2R Server can be used to integrate existing databases into RDF systems, and to add SPARQL interfaces to database-backed software products.
D2R Server combines the D2RQ API and Joseki SPARQL Server to map a database's contents into a virtual RDF graph that can be accessed over the SPARQL protocol. It is bundled with a Jetty webserver and aims at being easy to set up and use.
D2R Server is currently in an alpha state. It works for us, but has a minimal feature set and needs much more testing.
Requirements
You need:
- Java 1.4 or newer on the path (check with java -version if you're not sure),
- a D2RQ mapping file that describes how the tables and columns of your database should be mapped into RDF and how to connect to the database; the D2RQ Manual describes how to create one.
Installing and running D2R Server
Extract the archive into a suitable location. Optionally, add the extracted directory (where the d2r-server and d2r-server.bat files reside) to the path.
Change into the directory and run:
./d2r-server path/to/mappingfile.ttl (for Unix)
d2r-server c:\path\to\mappingfile.ttl (for Windows)(mappingfile.ttl is a D2RQ mapping file that describes how your database tables and columns are mapped to RDF and how to connect to the database – the D2RQ Manual describes how to create one)
Open http://localhost:2020/ in a web browser. The SPARQL endpoint is at http://localhost:2020/sparql.
Source code and development
D2R Server is hosted by SourceForge.net as part of the D2RQ project. The latest source code is available from the project's CVS repository and can be browsed online.
Support and feedback
You can contact us on the D2RQ mailing list at d2rq-map-devel@lists.sourceforge.net.