14.3.2.12 RDF Views from Relational Data

Starting from Graph Server and Client Release 25.3, you can easily create an RDF view graph using the RDF View Wizard in RDF Graph Server and Query UI. You can then run SPARQL queries on the RDF view graph and visualize the query output.

The wizard provides a structured step-by-step approach guiding you to create an R2RML mapping for viewing the contents of the relational tables as RDF triples. However, note that the mapping currently supports the generation of RDF triples only, not RDF quads. Also, the predicates in the mapping must be constants and cannot be based on the content of a row. Additionally, viewing resources as blank nodes is not supported in mappings that are created using the wizard.

Note:

Oracle Graph also provides subprograms to create, export, and drop RDF Views. See API Support for RDF Views for more information. An RDF view graph can be queried using SPARQL queries.

The RDF View Wizard is based on the following concepts:

• Resource Maps: These represent the mapping for obtaining the resources (nodes) in the graph structure. Each resource map contains the mapping for viewing the content of each row in a given entity table as a set of RDF triples. These triples use as subject the same resource, representing the entity corresponding to the row, along with all its properties.
• Triple Maps: These represent the mapping for obtaining the relationships (edges) between two resources (nodes) in the graph structure. Each triple map contains the mapping for viewing each binary relationship, captured in a row of the relationship table, as an RDF triple whose predicate reflects the type of relationship and whose subject and object are resources obtained using the referenced (source and target) resource maps.

The following section explains the steps to create, query, and visualize an RDF view graph using the wizard:

• Getting Started with the RDF View Wizard