JENA RDF/XML format rdfs example

Question

Can someone give me a working example (in Java code) of how to create a RDFS related statement like the following using Jena?

<rdf:Property rdf:about="http://www.help.me/confused/PropertyName">
    <rdfs:domain rdf:resource="http://www.help.me/confused/ClassName"/>
    <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</rdf:Property>

I created a RDF/XML schema by hand, and it validates right but somehow the entities won't work together in SPARQL (even with inference engine on). So, I decided to create the whole thing from start using the Jena API to ensure that it's correct.

Answer 1

I've changed the namespace a bit, just so that this code ends up pointing back to this post, but at any rate, I get this output:

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#">
  <rdf:Property rdf:about="http://stackoverflow.com/q/20194409/1281433/PropertyName">
    <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="http://stackoverflow.com/q/20194409/1281433/ClassName"/>
  </rdf:Property>
</rdf:RDF>

from this code:

import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.Property;
import com.hp.hpl.jena.vocabulary.RDFS;

public class JenaPropertyExample {
    public static void main(String[] args) {
        final String NS = "http://stackoverflow.com/q/20194409/1281433/";
        final Model model = ModelFactory.createDefaultModel();

        final Property p = model.createResource( NS+"PropertyName", RDF.Property ).as( Property.class );
        p.addProperty( RDFS.domain, model.createResource( NS+"ClassName" ));
        p.addProperty( RDFS.range, RDFS.Literal );

        model.write( System.out, "RDF/XML-ABBREV" );
    }
}

In general, just because the output is legal RDF doesn't mean that you're using the properties and classes in the way that's expected. Jena's plain Model interface can't help you too much with that, since you could still use the properties incorrectly, but at least, if you're using Jena's predefined vocabulary classes, you'll get the IRIs right. If you can use an OntModel, you can get a slightly nicer layer of abstraction, though. E.g., the following method produces the same RDF/XML output, but lets you use methods like createOntProperty and get the p rdf:type rdf:Property triple for free, and methods like addRange and addDomain:

public static void main2( String[] args ) {
    final String NS = "http://stackoverflow.com/q/20194409/1281433/";
    final OntModel model = ModelFactory.createOntologyModel( OntModelSpec.RDFS_MEM );
    OntProperty p = model.createOntProperty( NS+"PropertyName" );
    p.addDomain( model.getOntClass( NS+"ClassName" ));
    p.addRange( RDFS.Literal );
    model.write( System.out, "RDF/XML-ABBREV" );
}