Using Fuseki

Using OGIT in Apache Jena Fuseki

As OGIT is described in the RDF Turtle Syntax, it can be deployed in any triple store, i.e., a special kind of graph database that is optimised for RDF data. This allows us to query both the OGIT schema itself and data conforming to the schema using the SPARQL query language. The following steps help you to get started with Fuseki, the triple store based on and maintained by the Apache Jena project.

1. We will use the rapper command-line utility to merge all of OGIT’s turtle files into one file in N-Triples-Format. In a Debian-based system, you can install it by running apt-get install raptor2-utils. Clone the OGIT repository, then in the OGIT directory run:

   rapper -i turtle -o ntriples <(find . -name '*.ttl' -exec cat "{}" \;) > ogit.nt

2. Download and extract Fuseki.

3. Change to Fuseki’s directory and run ./fuseki-server --mem /OGIT. This starts Fuseki and creates an in-memory dataset called OGIT. You can also create persistent datasets, see Fuseki’s documentation for that.

4. Change to the bin/ directory. Here you will find scripts to upload and query data. To insert the ogit.nt into the OGIT dataset, run:

   ./s-put http://localhost:3030/OGIT default /path/to/OGIT/ogit.nt

5. Now let’s try a query on the OGIT schema. Fuseki’s web interface runs on http://localhost:3030/ by default. Open it and select query for the OGIT dataset. Paste the following SPARQL query: This will list the first 50 Entities defined in OGIT.

   PREFIX ogit: <http://www.purl.org/ogit/>
   PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
   
   SELECT ?entity ?name
   WHERE {
     ?entity rdfs:subClassOf ogit:Entity .
     ?entity rdfs:label ?name .
   }
   ORDER BY ?name
   LIMIT 50

6. You can get the same result in JSON-Format on the command line:

   ./s-query --service=http://localhost:3030/OGIT 'paste query here'

7. Of course you have many more options, for example, you can use the Java API or the standard SPARQL endpoint for queries and updates.