We recently published an OpenRefine fork that adds Virtuoso JDBC Driver support to the list of Data Sources accessible via the current DBMS-specific JDBC binding layer.
What follows are a collection of screenshots and associated notes that cover the process of producing an RDF-Turtle document from data returned from a SQL Query targeting Virtuoso’s live demo instance.
Demonstration Database (popular Northwind Database Schema)
Effect of configuring the JDBC connection using the following connection attributes:
- Data Source Name – OpenRefine JDBC Data Source Name
- Type – JDBC Driver Type
- Server Port – Database Server Port Number
- Server Host Name – Database Server Host Name
- User Name
Once connected, you simply issue a SQL Query as you would from any JDBC-client applications en route to the server which processes the query and returns a result-set (or solution).
The query result-set is then used as the basis for building a transformation mapping for generating RDF 3-tuple Relations (triples) from N-Tuples returned by a SQL RDBMS.
Virtuoso’s support for both SQL and SPARQL via JDBC also enables users exploit the powerful data access and navigational capabilities of SPARQL which can even include intelligent crawling over the massive LOD Cloud and the broader Web at large.
The screenshot that follows depicts the results of a SPARQL Query for listing instances of a Person Class as described by the FOAF Ontology.
Northwind N-Tuples to RDF 3-Tuple Relation Mappings – JSON document generated by OpenRefine
RDF-Turtle Document generated by OpenRefine from Northwind Database – using the mappings above