D2RQ – A Database to RDF Mapper
D2RQ exposes the contents of relational databases as RDF. It consists of:
- The D2RQ Mapping Language. Use it to write mappings between database tables and RDF vocabularies or OWL ontologies.
- The D2RQ Engine, a SPARQL-to-SQL rewriter that can evaluate SPARQL queries over your mapped database. It extends ARQ, the query engine that is part of Apache Jena.
- D2R Server, a web application that provides access to the database via the SPARQL Protocol, as Linked Data, and via a simple HTML interface.
Homepage and Documentation
Learn more about D2RQ at its homepage: http://d2rq.org/
Apache License, Version 2.0
Contact, feedback, discussion
Please use the issue tracker here on GitHub for feature/bug discussion and support requests.
Building from source
You need some tools in order to be able to build D2RQ. Depending on your operating system, they may or may not be already installed.
- git, for forking the source code repository from GitHub. Run
giton the command line to see if it's there.
- Java JDK v5 or later, for compiling Java sources. Run
javacon the command line to see if it's there.
- Apache Ant, for building D2RQ. Run
anton the command line to see if it's there.
Getting the source
Get the code by forking the GitHub repository and cloning your fork, or directly clone the main repository:
git clone firstname.lastname@example.org:d2rq/d2rq.git
Doing Ant builds
D2RQ uses Apache Ant as its build system. You can run
ant -p from the project's main directory to get an overview of available targets:
To run the D2RQ tools, you need to do at least
|ant all||Generate distribution files in zip and tar.gz formats|
|ant clean||Deletes all generated artefacts|
|ant compile||Compile project classes|
|ant compile.tests||Compile test classes|
|ant jar||Generate project jar file|
|ant javadoc||Generate Javadoc API documentation|
|ant tar||Generate distribution file in tar.gz format|
|ant test||Run tests|
|ant vocab.config||Regenerate Config vocabulary files from Turtle source|
|ant vocab.d2rq||Regenerate D2RQ vocabulary files from Turtle source|
|ant war||Generate war archive for deployment in servlet container|
|ant zip||Generate distribution file in zip format|
After building with
ant jar, you can test-run the various components. Let's assume you have a MySQL database called
mydb on your machine.
Generating a default mapping file
./generate-mapping -u root -o mydb.ttl jdbc:mysql:///mydb
This generates a mapping file
mydb.ttl for your database.
Dumping the database
./dump-rdf -m mydb.ttl -o dump.nt
dump.nt, a dump containing the mapped RDF in N-Triples format.
Running D2R Server
This starts up a server at http://localhost:2020/
Deploying D2R Server into a servlet container
/webapp/WEB-INF/web.xml to point the
configFile parameter to the location of your mapping file.
Build a war file with
Deploy the war file, e.g., by copying it into the servlet container's
Running the unit tests
The unit tests can be executed with
Some unit tests rely on MySQL being present, and require that two databases are created:
A database called
iswcthat contains the data from
echo "CREATE DATABASE iswc" | mysql -u root mysql -u root iswc < doc/example/iswc-mysql.sql
An empty database called