R2RML mappings for the MusicBrainz schema on an entity-by-entity basis.

While these mappings have been used in the past mainly for materializing the RDF graph, we propose to treat the RDF graph as virtual. For that purpose, we use the Virtual Knowledge Graph (VKG) system Ontop to set up a SPARQL endpoint.

A virtual machine is available (for use with VirtualBox, VMware, etc.) with a replicated MusicBrainz at https://musicbrainz.org/doc/MusicBrainz_Server/Setup.

Note that the file musicbrainz_config.properties must reflect your DB name:

• musicbrainz_db is the default for a snapshot
• musicbrainz_db_slave is the default for a replicated database

Download Apache Jena and define the JENA_DIR environment variable.

Download ontop-cli on https://github.com/ontop/ontop/releases and define the ONTOP_DIR environment variable.

cd MusicBrainz-R2RML
${JENA_DIR}/bin/rdfcat -out Turtle mappings/*.ttl > merged-mapping.ttl

${ONTOP_DIR}/ontop endpoint --mapping merged-mapping.ttl -p musicbrainz_config.properties