[Pellet-users] Save A-Box and java.lang.UnsupportedOperationException

[Michael Grove]

On Jan 31, 2008, at 1:11 PM, Christiane Telöken wrote:

> Dear Pellet-users,
>
> I am using Jena and Pellet 1.5 and I have an OWL-DL-ontology with  
> the expressivity ALCHF(D) which you will find in the attachment.
>
> I would like to add a statement to a model and save the model  
> separately. Doing this results in a warning and then in an exception.
>
> My statements are contained in this datastructure:
>
>   public ArrayList <Statement> statementResources = new ArrayList  
> <Statement> ();
>
> The code looks like:
>
>     Statement stmt = null;
>     Statement newStmt = null;
>     Resource res;
>     Property prop;
>     String obj;
>
>     SaveABox newAbox = currentAbox;
>
>     for (int i = 0; i < currentAbox.statementResources.size(); i++){
>       stmt = newAbox.statementResources.get(i);
>
>       if (stmt.getSubject().toString().equals(newElement)){
>         prop = stmt.getPredicate();
>         obj = stmt.getObject().toString();
>         newStmt = ontoModel.createStatement(res, prop, obj);
>
>         System.out.println (newStmt);
>
>
> ###################################################################### 
> ############
> The statement looks fine and correct:
> [http://www.owl-ontologies.com/ 
> Ontology1200661107.owl#NewInstance_1, http://www.owl-ontologies.com/ 
> Ontology1200661107.owl#hasGoal, "http://www.owl-ontologies.com/ 
> Ontology1200661107.owl#InGoalRadium224"]
> ###################################################################### 
> ############
>
>
>         Model model = ontoModel.add(res, prop, obj);
>
> ###################################################################### 
> ############
> Here, Pellet gives a warning:
>  WARN [main] (KnowledgeBase.java:773) - Ignoring literal value  
> literal(http://www.owl-ontologies.com/ 
> Ontology1200661107.owl#InGoalRadium224,(),()) for object property  
> http://www.owl-ontologies.com/Ontology1200661107.owl#hasGoal
> ###################################################################### 
> ############
>

It's been awhile since I've used Jena with any regularity, so I might  
just be stabbing in the dark here, especially without seeing how you  
create your model (is it an in-mem model?), but I *think* you're  
seeing the expected behavior.  Any Jena experts can feel free to  
correct me =)

>
>         try{
>           model.commit();

This commits the current transaction in the model. If you're using an  
in-mem model, I believe the default is no transaction support (see  
SimpleTransactionHandler which is used by GraphBase by default), and  
if that is the case, that is the cause of the exception you pasted.   
I suspect if you printed the whole stack trace, you'd see it coming  
out of the jena code, and not pellet -- it's probably being thrown by  
the aforementioned SimpleTransactionHandler.  If this is your attempt  
to write the model to disk, this is the incorrect way to do this.   
Look at the getWriter() function, or any of the write(...) methods on  
Model which take an outputstream as an argument.

As always, the jena javadocs are useful:

http://jena.sourceforge.net/javadoc/index.html

Cheers,

Mike

>         }
>         catch (Exception e){
>           System.out.println (e);
>         }
>
> ###################################################################### 
> ############
> Pellet throws this exception:
> java.lang.UnsupportedOperationException: this model does not  
> support transactions
> ###################################################################### 
> ############
>       }
>     }
>   }
>
> The objective of my work is to change the A-Box of the ontology and  
> save it separately. As I am a newbie to Pellet and the Jena- 
> framework I am not sure if this is the way I should do it.
>
> I would be very glad for any hints why the warning and exception is  
> thrown and would be very grateful if somebody could tell me if this  
> is the right way to save the A-Box of the ontology.
>
> Thank you for any help in advance,
>
> Christiane
>

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