D2RQ ACCESS RDB AS VIRTUAL RDF(LAGECY DATA MEETS THE GLOBAL DATASETS)
What can it Do ?• Access RDB as RDF read only graphs.• Access RDB without "REPLICATION" into Triplestore as RDF.• Make your content available as RDF and exploit it with Linked Data Methodologies.• Its Open Source, having Apache License, Version 2.0• Supports various DB vendors.
Features• Query Non-RDF database using SPARQL• Access the Content of non-RDF databases as Linked Data over the web. This makes legacy data make sense.• Helps in dumps creations in order to load data into the Triple stores.• Helps in accessing Non-RDF databases or RDB using Apache-Jena.• Provides an AJAX based Query Browser for Querying RDB using SPARQL.
What this Platform has for me/us?• A mapping language which connects the RDB database with the existing set of ontologies• D2RQ Engine that integrates seamlessly with Apache Jena to process SPARQL upon the RDB.• D2RQ server which acts as a port for viewing Linked Data over the web.• It also Provides SPARQL endpoint with AJAX enabled endpoint.
How does the mapping happen ?• D2RQ has a Mapping Language that does direct mapping of the RDB to RDF.• D2RQ Provides a tool to generate a custom mapping for the above purpose.• Mappings treat Database Tables as Classes and the Column name as the Properties to the Classes.• D2RQ also provides a bridge to map the individual to the Domain Knowledge i.e Ontologies.
Features of D2RQ Server• Gives you Browsable content in RDF format (Human Readable), through which one can navigate• Resolvable URIs• Content Negotiation• SPARQL endpoint explorer, Supports SPARQL1.1. Queries over SPARQL Protocol• Can be configured to serve files stored in Databases CLOB/BLOB• Serving Vocabulary• Publishing Meta Data
Basic Architecture of how D2RQ fits in with RDB
Databases Supported By D2RQ• Oracle• MySQL (Drivers are provided by D2RQ)• PostgreSQL (Drivers are provided by D2RQ)• SQL Server• HSQLDB• Interbase/Firebird• ODBC Datasources (With help of ODBC-JDBC Bridge but has limitations)
Getting Started• Download D2RQ• Generate the Mapping file against a compatible Database• There is a tool included that would generate mapping after throughly inspecting your database• Modify the mapping file if required• Run the D2RQ server along with the Mapping file• Thats DONE!!!• Now SPARQL your RDB and get the results of your choice