Your SPARQL query needs to declare the prefix for OWL: PREFIX owl: <http://www.w3.org/2002/07/owl#> SELECT distinct ?c ?p WHERE { ?c a owl:Class } LIMIT 10
Also for this query you don't need the "addGraphURI" or the Model since you are using QueryExecutionFactory.sparqlService See here for some commentary on it: http://linkedjava.blogspot.com/2011/06/two-ways-to-query-linked-data-with-arq.html Here is a gist with this query working: https://gist.github.com/1073737 Al On Fri, Jul 8, 2011 at 7:06 PM, 朱曼 <[email protected]> wrote: > Dear list, > > hi~~ > > I encounter "HttpException: java.net.SocketException: Connection reset: > java.net.SocketException: Connection reset" exception when I run the > following code, could you help me? > > try { > Model dbpedia_model = ModelFactory.createDefaultModel(); > String queryStr = "SELECT distinct ?c WHERE { ?c a owl:Class }"; > Query query = QueryFactory.create(queryStr); > query.addGraphURI("http://dbpedia.org/";); > QueryExecution qexec = QueryExecutionFactory.sparqlService(" > http://dbpedia.org/sparql";, query); > ResultSet rs = qexec.execSelect(); > ResultSetFormatter.out(System.out, rs, query); > qexec.close(); > } catch (Exception e) { > e.printStackTrace(); > } > > all the best > > June >
