jena

I'm a Java developer just getting started with linked data/RDF. I can create triples, put them in a triple store, query them, etc, but it's very awkward. Most of my code is focused on the mechanics of RDF and I'd really like to work with this data in a way that's more idiomatic Java. How can I convert a POJO to/from RDF triples with Jena without hand-coding everything? I'd like something that can convert a pile of triples with a defined structure back and forth between a Java POJO and RDF. Like JAXB or and ORM does for XML and a relational database, respectively. Also, I can't be locked in too

Im trying to create a SPARQL query using Jena to query DBpedia. The query is working when I use it with standalone tools (Twinkle) but when I plug it in this Java code it returns an empty set. String sparqlQueryString1 = "PREFIX dbont: <http://dbpedia.org/ontology/> " + "PREFIX dbp: <http://dbpedia.org/property/>" + "PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#>" + " SELECT ?musician ?place" + " FROM<http://dbpedia.org/resource/Daphne_Oram>" + " WHERE { " + " ?musician dbont:birthPlace ?place ." + " }"; Query query = QueryFactory.create(sparqlQueryString1); QueryExecution qexec =

I am using Jena ARQ to write a SPARQL query against a large ontology being read from Jena TDB in order to find the types associated with concepts based on rdfs label: SELECT DISTINCT ?type WHERE { ?x <http://www.w3.org/2000/01/rdf-schema#label> "aspirin" . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?type . } This works pretty well and is actually quite speedy (<1 second). Unfortunately, for some terms, I need to perform this query in a case-insensitive way. For instance, because the label "Tylenol" is in the ontology, but not "tylenol" , the following query comes up empty: SELECT

i downloaded the Database dump of Freebase. The format of the file is rdf turtle. I need to get all the data into the neo4j database. I already wrote an importer with help of tinkerpop.blueprints. First it seemed to work but after 30 minutes of importing an exception occured because the rdf file contained characters at positions where they are not allowed to be. A little bit later (after some investigation) i found out that the jena parser i used (RDFReader) is deprecated and shouldnt be used. What i need to know now: Is there any way to import that rdf file into neo4j? Jena is able to

I'm writing a code generator that generate entities (POJO's in Java language) from the schema defined here http://schema.rdfs.org/all.ttl . I'm using Jena to parse the ttl file and retrieve the meta data that I need to generate them. Jena parses the file successfully, however, for some reason it does not list all the attributes of a given entity, e.g., Person. I'm not sure whether I'm doing something wrong, using the wrong API, etc. Here's the code sample that recreates the scenario: public class PersonParser { public static void main(String[] args) { OntModel model = ModelFactory

I'm using Jena TDB for loading an RDF dataset and making SPARQL queries against it. I'm using the following maven dependency: <dependency> <groupId>org.apache.jena</groupId> <artifactId>apache-jena-libs</artifactId> <type>pom</type> <version>3.0.1</version> </dependency> And here's the java code where I'm trying to create a TDB dataset: public void loadDirectory(String outputFile){ Dataset dataset = TDBFactory.createDataset(directoryPath); Model tdb = dataset.getDefaultModel(); FileManager.get().readModel(tdb, outputFile); tdb.close(); dataset.close(); LOG.info("RDF dataset loaded to memory");