Quering dbpedia with SPARQL and Jena.

Question

Hi Guys. I cannot understand how can I query dbpedia.org using Jena. In the tutorials like here(Listing 4) model is initialized as follows:

// Open the bloggers RDF graph from the filesystem
InputStream in = new FileInputStream(new File("bloggers.rdf"));

// Create an empty in-memory model and populate it from the graph
Model model = ModelFactory.createMemModelMaker().createModel();
model.read(in,null); // null base URI, since model URIs are absolute
in.close();

Let's say I want to write a query that will list churches in Paris. In SPARQL language it will look like:

PREFIX p: <http://dbpedia.org/property/&gt;
PREFIX dbpedia: <http://dbpedia.org/resource/&gt;
PREFIX category: <http://dbpedia.org/resource/Category:&gt;
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#&gt;
PREFIX skos: <http://www.w3.org/2004/02/skos/core#&gt;
PREFIX geo: <http://www.georss.org/georss/&gt;

SELECT DISTINCT ?m ?n ?p ?d
WHERE {
 ?m rdfs:label ?n.
 ?m skos:subject ?c.
 ?c skos:broader category:Churches_in_Paris.
 ?m p:abstract ?d.
 ?m geo:point ?p
 FILTER ( lang(?n) = "fr" )
 FILTER ( lang(?d) = "fr" )
 }

source is here.

How this query will look in Java. Particularly I'm interested how model object is initialization.

Thanks in advance.

Answer 1

After browsing tones and tones of pages I found the answer. Perhaps I didn't ask the question clearly enough but anyway bellow is the code that worked for me.

String query=
"PREFIX p: <http://dbpedia.org/property/&gt;"+
"PREFIX dbpedia: <http://dbpedia.org/resource/&gt;"+
"PREFIX category: <http://dbpedia.org/resource/Category:&gt;"+
"PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#&gt;"+
"PREFIX skos: <http://www.w3.org/2004/02/skos/core#&gt;"+
"PREFIX geo: <http://www.georss.org/georss/&gt;"+

"SELECT DISTINCT ?m ?n ?p ?d"+
"WHERE {"+
" ?m rdfs:label ?n."+
" ?m skos:subject ?c."+
" ?c skos:broader category:Churches_in_Paris."+
" ?m p:abstract ?d."+
" ?m geo:point ?p"+
" FILTER ( lang(?n) = "fr" )"+
" FILTER ( lang(?d) = "fr" )"+
" }"

// now creating query object
Query query = QueryFactory.create(queryString);
// initializing queryExecution factory with remote service.
// **this actually was the main problem I couldn't figure out.**
QueryExecution qexec = QueryExecutionFactory.sparqlService("http://dbpedia.org/sparql", query);

//after it goes standard query execution and result processing which can
// be found in almost any Jena/SPARQL tutorial.
try {
    ResultSet results = qexec.execSelect();
    for (; results.hasNext();) {

    // Result processing is done here.
    }
}
finally {
   qexec.close();
}

This answer I found on dbpedia-discussion of www.mail-archive.com page