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jenaowl-apiturtle-rdf

Load Ontology serialized in Turtle using OWL API

I am trying to load an ontology from a Jena model using OWL API, but most of the axioms are appearing as annotations.

The ontology in Turtle is shown below. I use a Jena model to store it. NB: The ontology below is not correct, as mentioned in answers down

@prefix owl:   <http://www.w3.org/2002/07/owl#> .
@prefix rdf:   <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix xsd:   <http://www.w3.org/2001/XMLSchema#> .
@prefix rdfs:  <http://www.w3.org/2000/01/rdf-schema#> .

<http://example.com/minimalDecoupling>
        a           "http://www.w3.org/2002/07/owl#DatatypeProperty" ;
        rdfs:label  "minimal decoupling" .

<http://example.com/frequency>
        a           "http://www.w3.org/2002/07/owl#DatatypeProperty" ;
        rdfs:label  "frequency" .

<http://example.com/voltage>
        a           "http://www.w3.org/2002/07/owl#DatatypeProperty" ;
        rdfs:label  "Voltage" .

<http://example.com/powerConsumed>
        a           "http://www.w3.org/2002/07/owl#DatatypeProperty" ;
        rdfs:label  "power consumed" .

<http://example.com/installation>
        a           "http://www.w3.org/2002/07/owl#DatatypeProperty" ;
        rdfs:label  "installation" .

<http://example.com/Device>
        a           "http://www.w3.org/2002/07/owl#Class" ;
        rdfs:label  "device" .

<http://example.com/dimension>
        a           "http://www.w3.org/2002/07/owl#DatatypeProperty" ;
        rdfs:label  "dimension" .

<http://example.com/>
        a       "http://www.w3.org/2002/07/owl#Ontology" .

Suppose that the above ontology is stored in the Jena model ontologyGraph, I am using the code below to load the Jena model as an OWL ontology.

OWLOntology ontology = ontologyManager.
                loadOntologyFromOntologyDocument
                        (new ByteArrayInputStream(Ontology.toTurtle(ontologyGraph).getBytes()));

The toTurtle method is shown below:

public static String toTurtle(Model ontologyGraph){
        StringWriter out = new StringWriter();
        ontologyGraph.write(out,"TTL");
        return out.toString();
    }

However, as we see in the output below, the axioms from the ontology are appearing annotation axiom:

Ontology(OntologyID(Anonymous-2)) [Axioms: 15 Logical Axioms: 0] First 20 axioms: {AnnotationAssertion(rdfs:label http://example.com/powerConsumed "power consumed") AnnotationAssertion(rdfs:label http://example.com/minimalDecoupling "minimal decoupling") AnnotationAssertion(rdf:type http://example.com/ "http://www.w3.org/2002/07/owl#Ontology") AnnotationAssertion(rdfs:label http://example.com/dimension "dimension") AnnotationAssertion(rdf:type http://example.com/dimension "http://www.w3.org/2002/07/owl#DatatypeProperty") AnnotationAssertion(rdf:type http://example.com/voltage "http://www.w3.org/2002/07/owl#DatatypeProperty") AnnotationAssertion(rdf:type http://example.com/Device "http://www.w3.org/2002/07/owl#Class") AnnotationAssertion(rdfs:label http://example.com/installation "installation") AnnotationAssertion(rdfs:label http://example.com/voltage "Voltage") AnnotationAssertion(rdf:type http://example.com/minimalDecoupling "http://www.w3.org/2002/07/owl#DatatypeProperty") AnnotationAssertion(rdf:type http://example.com/frequency "http://www.w3.org/2002/07/owl#DatatypeProperty") AnnotationAssertion(rdfs:label http://example.com/Device "device") AnnotationAssertion(rdf:type http://example.com/powerConsumed "http://www.w3.org/2002/07/owl#DatatypeProperty") AnnotationAssertion(rdfs:label http://example.com/frequency "frequency") AnnotationAssertion(rdf:type http://example.com/installation "http://www.w3.org/2002/07/owl#DatatypeProperty") }

My questions are:

  1. why are all the axioms appearing as annotations ?
  2. Is it possible to directly load a Jena model as an OWL ontology using OWL API without having to pass through Turtle ?
Solution

  • Why are all the axioms appearing as annotations?

    The types in the input model are string literals, but they need to be IRIs. For example this one:

    <http://example.com/Device>
    a "http://www.w3.org/2002/07/owl#Class" ;

    It should be:

    <http://example.com/Device>
    a <http://www.w3.org/2002/07/owl#Class> ;

    Which would then be abbreviated automatically as:

    <http://example.com/Device>
    a owl:Class ;

    Is the ontology in the input Jena model created using the Jena API? In that case, the code needs to be changed to create IRIs (also known as “Resources” or “URIResources” in Jena) instead of string literals.

    Is it possible to directly load a Jena model as an OWL ontology using OWL API without having to pass through Turtle?

    There is no way to directly load a Jena model into OWL-API, but there certainly are options that avoid the round-trip through Turtle, like ONT-API.