D2RQ extension for data cubes
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The D2RQ OpenCube component enables generation of the RDF graph from a relational table. The component builds upon the D2RQ Open-Source platform. It leverages R2RML language (a W3C standard) for mappings from relational databases to RDF datasets.
How it works
The current implementation of the D2RQ Extension supports XML as metadata format for relational database description. The file is used as the source for the R2ML mapping file generation. The improved R2R (RDF to RDF) mapping that will replace the current XML solution will be implemented in the later stage of the development.
D2RQ Extensions for Data Cube covers the functionality of importing of raw data as data cubes by transformation of relational data to RDF using R2RML mapping.
The user, by providing information about the dataset, such as the data dimensions and related measures as the XML file, will receive an R2RML mapping file, which as a result is used to generate and store the output in the SPARQL endpoint.
The process of mapping the data cube with a relational data source includes: (a) mapping the tables to classes of entities, (b) mapping selected columns into cube dimensions and cube measures, (c) mapping selected rows into observation values, and (d) generate triples with data structure definition.
The extension is integrated with the Information Workbench as a standard Data Provider. The interface delivered enables user to specify the basic information about the provider along with the location of the SQL file (with relational data), polling intervals and to modify the dataset description.