On the Web, most OWL and RDF content are formatted as as RDF/XML. This format works great for the web, and most OWL/RDF tools support this as the native format. However, it is less human-readable than other formats such as Turtle.
For me, Turtle is the easiest form to read, and the quickest format for generating test data when I am prototyping. But not all tools support Turtle format.
But that's OK! If you want to easily convert from RDF/XML to Turtle and back, you can use the freely available Jena utilities to do this. These are command line utilities, so you run them from a command window.
First: Download Jena. The latest version at the time of this writing is version 2.6.2. Unpack it anywhere - though I usually make sure the directory path has no spaces in it. E.g., let's say you unpack it on a Windows system under C:\Programs, making the Jena top level folder the C:\Programs\Jena-2.6.2 folder.
Second: Set up your Java classpath, e.g.:
set CLASSPATH=
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\arq-extra.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\arq.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\icu4j_3_4.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\iri.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\jena.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\jenatest.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\json.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\junit-4.5.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\log4j-1.2.12.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\lucene-core-2.3.1.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\slf4j-api-1.5.6.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\slf4j-log4j12-1.5.6.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\stax-api-1.0.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\wstx-asl-3.0.0.jar
set CLASSPATH=%CLASSPATH%;C:\Programs\Jena-2.6.2\lib\xercesImpl.jar
Third: Convert stuff! E.g. I have the file vehicle.owl, with these contents:
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:e="http://example.org/ex#"
xmlns:owl="http://www.w3.org/2002/07/owl#"
xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#">
<rdfs:Class rdf:about="http://example.org/ex#Vehicle"/>
<e:Civic rdf:about="http://example.org/ex#Civic_8717383">
<e:hasVin>1H0243098430987</e:hasVin>
</e:Civic>
<rdfs:Property rdf:about="http://example.org/ex#hasVin"/>
<rdf:Description rdf:about="http://example.org/ex#HondaCar">
<rdfs:subClassOf>
<rdf:Description rdf:about="http://example.org/ex#Car">
<rdfs:subClassOf rdf:resource="http://example.org/ex#Vehicle"/>
</rdf:Description>
</rdfs:subClassOf>
</rdf:Description>
<rdf:Description rdf:about="http://example.org/ex#Civic">
<rdfs:subClassOf rdf:resource="http://example.org/ex#HondaCar"/>
</rdf:Description>
</rdf:RDF>
To convert it, I use the Jena rdfcat program, as follows:
java jena.rdfcat -out ttl vehicle.owl
And it prints this this out:
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix e: <http://example.org/ex#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
e:Civic_8717383
a e:Civic ;
e:hasVin "1H0243098430987" .
e:Vehicle
a rdfs:Class .
e:HondaCar
rdfs:subClassOf e:Car .
e:hasVin
a rdfs:Property .
e:Car
rdfs:subClassOf e:Vehicle .
e:Civic
rdfs:subClassOf e:HondaCar .
I can redirect this to a file for safe keeping:
java jena.rdfcat -out ttl vehicle.owl > vehicle.ttl
Now I have my turtle file! I can view and edit it as I see fit. Then, if I need to publish back to RDF/XML format, I simply use the rdfcat utility again, but with no "-out" option:
java jena.rdfcat vehicle.ttl > vehicle-new.owl
That's it. If this was new to you, post a comment and let me know if it helped.
