Loading owl file with Jena

Question

I load several OWL files (RDF/XML serialization) with Jena as OntModel. For some files I get an error when reading them with ontoModel.read():

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/http/HttpMessage.

I have org.apache.httpcore-sources.jar in the classpath.

The file which currently poses problem is: ontologydesignpatterns.org/cp/owl/timeindexedpersonrole.owl

I saved it with Protege as RDF/XML, trying with both extensions .owl and .rdf.

The code:

public static OntModel getOntologyModel(String ontoFile)
{   
    OntModel ontoModel = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM, null);
    try 
    {
        InputStream in = FileManager.get().open(ontoFile);
        try 
        {
            ontoModel.read(in, null);
        } 
        catch (Exception e) 
        {
            e.printStackTrace();
        }
        LOGGER.info("Ontology " + ontoFile + " loaded.");
    } 
    catch (JenaException je) 
    {
        System.err.println("ERROR" + je.getMessage());
        je.printStackTrace();
        System.exit(0);
    }
    return ontoModel;
}

Many thanks for your help.

I am able to load your file with your code. Make sure that you are passing owl file with correct name. Code is correct. — Haroon Lone, Jun 11 '15 at 05:36
Thanks. I triple-checked, the file name is correct and the file exists. The error is actually coming from `org.apache.jena.riot.system.stream.LocatorHTTP.performOpen(LocatorHTTP.java:41)`. I also tried to put the base name as arg of the read method, but same error for the same file. Might be a stupid error somewhere, but I do not manage to spot it. — ecrin, Jun 11 '15 at 07:12
The file linked has imports to other ontologies - one of them might be the problem. I'd try loading each one to see if anything useful emerges. — Ignazio, Jun 11 '15 at 07:26
Thanks, you're right that might the imports. There is actually a chain of imports; other files pose problem as well, which make the whole stuff quite cumbersome. I think I will just hard-code the few classes of my initial file... — ecrin, Jun 11 '15 at 08:19
`ontoModel.read(ontoFile);` will work (unless quite old Jena) if the file name has an extension. — AndyS, Jun 11 '15 at 08:19
Reading the file directly does not work (for this file only) and hit the same error. Someone else got a similar pb when reading owl file with imports, but no solution: http://stackoverflow.com/questions/29850654/how-to-read-ontology-file-with-owlimports-in-jena. Thanks to all for your feedback. — ecrin, Jun 11 '15 at 08:25

score 1 · Accepted Answer · answered Jun 11 '15 at 08:19

If you are using the binary download, put all the jars in the lib/ directory on the classpath. org.apache.httpcore-sources.jar isn't the right jar.. You seem to be missing at least httpclient-4.2.6.jar and httpcore-4.2.5.jar.

If you use maven, use the artifact:

<dependency>
 <groupId>org.apache.jena</groupId>
 <artifactId>apache-jena-libs</artifactId>
 <type>pom</type>
 <version>X.Y.Z</version>
</dependency>

to get the same set, but managed by maven, or whatever builer you are using.

Hello, thanks, that was it! Simply missing the good libraries to handle the imports. Now it works :) — ecrin, Jun 11 '15 at 09:26

Loading owl file with Jena

1 Answers1

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