Ontop is a framework for ontology based data access (OBDA). It supports SPARQL over virtual RDF graphs defined through mappings to RDBMS.
The -ontop- framework is available under the Apache License, Version 2.0
All documentation is licensed under the Creative Commons (attribute) license.
Compiling, packing, testing, etc.
The project is a Maven project. Compiling, running the unit tests, building the release binaries all can be done using maven. To make it more practical we created several .sh scripts that you can run on any unix environment that has maven installed. The scripts are located in the folder 'scripts', look at that folder for more information.
Currently we use Maven 3 and Java 7 to build the project.
official website and documentations: http://ontop.inf.unibz.it/
Google Group: https://groups.google.com/forum/#!forum/ontop4obda
Source Code: https://github.com/ontop/ontop
Issue Tracker: https://github.com/ontop/ontop/issues