Hey everyone, I'm developing an app to represent weather data in a semantic dataset using Jena and TDB. I've got all the data into Jena but I'm having trouble updating it. Every 3 hours for every weather monitoring station in my dataset I would like to be able to delete all old observations and replace them with new predictions.
An example of my RDF xml representing a *#LandMeterologicalStation* in Southampton, an *#MeteorlogicalObservation* for this station and the associated */2006/time#Instant *time/date object. *RDF/XML:* *<rdf:Description rdf:about="http://www.witw.com/Data/Stations/Southampton";> * * <rdf:type rdf:resource=" http://www.semanticweb.org/ontologies/2012/1/monitoringStation.owl#LandMeterologicalStation "/>* * <wgs84_pos:location>http://www.witw.com/Data/Points/1234 </wgs84_pos:location>* * <j.0:currentObservation> http://www.witw.com/Data/Observations/1234_2012-04-11T10:31:24.184+01:00 </j.0:currentObservation>* * <j.0:predictedObservation> http://www.witw.com/Data/Observations/1234_2012-04-11T10:31:24.258+01:00 </j.0:predictedObservation>* * <j.0:predictedObservation> http://www.witw.com/Data/Observations/1234_2012-04-11T10:32:22.577+01:00 </j.0:predictedObservation>* * <j.0:predictedObservation> http://www.witw.com/Data/Observations/1234_2012-04-11T10:42:36.491+01:00 </j.0:predictedObservation>* * <j.0:spatialGranularity rdf:datatype=" http://www.w3.org/2001/XMLSchema#integer";>1</j.0:spatialGranularity>* * <j.0:stationContinent rdf:datatype=" http://www.w3.org/2001/XMLSchema#string";>UK</j.0:stationContinent>* * <j.0:stationCountry rdf:datatype=" http://www.w3.org/2001/XMLSchema#string";>England</j.0:stationCountry>* * <j.0:stationId rdf:datatype="http://www.w3.org/2001/XMLSchema#string ">1234</j.0:stationId>* * <j.0:stationName rdf:datatype="http://www.w3.org/2001/XMLSchema#string ">Southampton</j.0:stationName>* * </rdf:Description>* * * * <rdf:Description rdf:about=" http://www.witw.com/Data/Observations/1234_2012-04-11T10:31:24.258+01:00";>* * <rdf:type rdf:resource=" http://www.semanticweb.org/ontologies/2012/1/monitoringStation.owl#MeteorlogicalObservation "/>* * <j.0:observationTime> http://www.witw.com/Data/Instants/1234_2012-04-11T10:31:24.258+01:00 </j.0:observationTime>* * <j.0:temperature rdf:datatype="http://www.w3.org/2001/XMLSchema#integer ">2</j.0:temperature>* * <j.0:temperatureFeelsLike rdf:datatype=" http://www.w3.org/2001/XMLSchema#integer";>3</j.0:temperatureFeelsLike>* * <j.0:uvIndex rdf:datatype="http://www.w3.org/2001/XMLSchema#integer ">1</j.0:uvIndex>* * <j.0:visibility rdf:datatype="http://www.w3.org/2001/XMLSchema#string ">VG</j.0:visibility>* * <j.0:weatherType rdf:datatype="http://www.w3.org/2001/XMLSchema#integer ">2</j.0:weatherType>* * <j.0:windDir rdf:datatype="http://www.w3.org/2001/XMLSchema#double ">180.0</j.0:windDir>* * <j.0:windSpeed rdf:datatype="http://www.w3.org/2001/XMLSchema#integer ">4</j.0:windSpeed>* * <j.0:windSpeedGust rdf:datatype=" http://www.w3.org/2001/XMLSchema#integer";>5</j.0:windSpeedGust>* * </rdf:Description>* * * * <rdf:Description rdf:about=" http://www.witw.com/Data/Instants/1234_2012-04-11T10:31:24.258+01:00";> <rdf:type rdf:resource="/2006/time#Instant"/> <j.1:inXSDDateTime rdf:datatype=" http://www.w3.org/2001/XMLSchema#dateTime ">2012-04-11T09:31:24.258Z</j.1:inXSDDateTime> </rdf:Description> * * <rdf:Description rdf:about=" http://www.semanticweb.org/ontologies/2012/1/monitoringStation.owl#MeteorlogicalObservationWind ">* * <rdf:type rdf:resource="#Class"/>* * </rdf:Description>* * * *Code snippet:* * * * /*** * * Used when no current database for the RDF model exists. Loads an ontology* * * from the ontologyPath provided by the Spring config file and builds a* * * database at the provided tbdDBPath.* * */* * public void setUpDatabase() {* * logger.info("Setting Up RDF Database");* * logger.info("Database Path: " + tbdDBPath);* * logger.info("Ontology Path: " + ontologyPath);* * * * dataset = TDBFactory.createDataset(tbdDBPath);* * model = dataset.getDefaultModel();* * ontModel = ModelFactory* * .createOntologyModel(OntModelSpec.OWL_MEM, model);* * ontModel.read(ontologyPath);* * model.commit();* * logger.info("Database UP :)");* * } * * public boolean removeAllStationProperties(String individualSubjectURI,* * String propertyObjectURI, String individualObjectURI) {* * * * logger.info("Trying to remove object with URI: " + propertyObjectURI);* * * * String encodedIndividualSubjectURI = URIref* * .encode(individualSubjectURI);* * String encodedPropertyObjectURI = URIref.encode(propertyObjectURI);* * String encodedIndividualObjectURI = URIref.encode(individualObjectURI);* * * * dataset.begin(ReadWrite.WRITE);* * model = dataset.getDefaultModel();* * * * ontModel = ModelFactory* * .createOntologyModel(OntModelSpec.OWL_MEM, model);* * try {* * Individual individualSubject = ontModel* * .getIndividual(encodedIndividualSubjectURI);* * * * Resource objectResource = ontModel* * .getResource(encodedIndividualObjectURI);* * OntClass thisClass = objectResource.as(OntClass.class);* * Iterator classIterator = thisClass.listInstances();* * * * while (classIterator.hasNext()) {* * OntResource thisResource = (OntResource) classIterator.next();* * classIterator.remove();* * }* * * *// Second method of removing objects. * *// * *// Property thisProperty = ontModel* *// .getProperty(encodedPropertyObjectURI);* *//* *// Individual individualObject = ontModel* *// .getIndividual(encodedIndividualObjectURI);* *//* *// ontModel.remove(individualSubject, thisProperty, individualObject);* * * * * *// Third method attempted* *//* *// individualObject.removeProperties();* *// individualObject.remove(); * * * * dataset.commit();* * logger.info("Sucessfully removed object and all properties: "* * + propertyObjectURI);* * return true;* * * * } finally {* * dataset.end();* * }* * }* I've tried using the following above method to delete all the * #MeteorlogicalObservation** *instances but to no avail after 3 different approaches: 1. Using an iterator over all the instances of the Class * #MeteorlogicalObservation.* 1. Throws UnsupportedOperationException 2. Calling ontModel.remove() and a predicate describing the relationship. 3. Calling removeProperties() and remove on the * #LandMeterologicalStation.* 1. This deletes all the *#LandMeterologicalStation *objects but not the *#MeteorlogicalObservations.* To test I call removeAllStationProperties(); using: * witwDataAdaptor* * .removeAllStationProperties(* * witwDataAdaptor.getLandStationIndividualURIPrefix()* * + "Southampton",* * " http://www.semanticweb.org/ontologies/2012/1/witwWorldModel.owl#predictedObservation ",* * " http://www.semanticweb.org/ontologies/2012/1/monitoringStation.owl#MeteorlogicalObservation ");* * * My main question is what is the best way to search for and delete all instances of a class? Including deleting all associated class objects. In this example, I'd like to delete all *#MeteorlogicalObservation * and associated *#Instant *objects for a given *#LandMeterologicalStation* URI. Thanks in advance for any help you guys can offer and sorry if its a big post, I've tried to be as complete as possible :) Herbie
