Importing RDF

Revision as of 15:12, 13 October 2006

Wandora reads RDF(S) and N3 files. Import starts with File > Import > Simple RDF(S) Import... or File > Import > Simple N3 Import.... Wandora converts imported RDF triplets to topics, associations and occurrences. Convert schema is very simple and pays no attention to semantics of RDF for example. Lets see the conversion process more detailed.

A topic is always created for RDF subject and predicate. Topics created for the subject and predicate are typed with Wandora's predefined type topics.

If object is RDF literal an occurrence (text data) is created for the topic created with the subject. Occurrence's type is topic created for the predicate and value the RDF literal.

If object is not RDF literal a topic is created for the object and the topic is associated with the topic created for the subject. Association's type is set the topic created for the predicate. Both roles are Wandora's predefined topics. Object topic is typed with Wandora's predefined type topic.

All created topics contain no basename or variant names but inherit one subject identifier from equivalent RDF resource. Below is the Java code snippet used to handle RDF statements in Wandora:

   public void handleStatement(Statement stmt, TopicMap map,
                               Topic subjectType,
                               Topic predicateType,
                               Topic objectType) throws TopicMapException {
       
       Resource subject   = stmt.getSubject();     // get the subject
       Property predicate = stmt.getPredicate();   // get the predicate
       RDFNode object     = stmt.getObject();      // get the object
       
       Topic subjectTopic = getOrCreateTopic(map, subject.toString());
       Topic predicateTopic = getOrCreateTopic(map, predicate.toString());
       
       subjectTopic.addType(subjectType);
       predicateTopic.addType(predicateType);
      
       if(object.isLiteral()) {
           subjectTopic.setData(predicateTopic,
                                getOrCreateTopic(map, occurrenceScopeSI), ((Literal) object).getString());
       }
       else if(object.isResource()) {
           Topic objectTopic = getOrCreateTopic(map, object.toString());
           Association association = map.createAssociation(predicateTopic);
           association.addPlayer(subjectTopic, subjectType);
           association.addPlayer(objectTopic, objectType);
           objectTopic.addType(objectType);
       }
       else if(object.isURIResource()) {
           log("URIResource found but not handled!");
       }        
   }