I think it was the problem of not including the right prefix. I included it, the error goes away but it just ouput "null". I do not know why, but it gives me the result at SPARQL endpoint, but in Jena, it shows null as output.
On Mon, Feb 29, 2016 at 12:30 PM, Andy Seaborne <[email protected]> wrote: > What have you tried? > > Before firing off questions, try to solve basic java issues using google, > stackoverflow etc. > > Caused by: java.net.UnknownHostException: dbpedia.org > > so it's a networking issue in your environment. > Firewall, misconfigured DNS etc. > > Study the output of > nslookup dbpedia.org > > Andy > > > On 29/02/16 11:29, Lorenz B. wrote: > >> It has to be http://dbpedia.org/sparql >> >> Hello I am getting this exception when I run jena against dbpedia. >>> What is >>> the problem? >>> ++++++++++++++++++++++++++++++++++ >>> :WARN No appenders could be found for logger >>> (org.apache.jena.riot.system.stream.JenaIOEnvironment). >>> log4j:WARN Please initialize the log4j system properly. >>> log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for >>> more info. >>> HttpException: java.net.UnknownHostException: dbpedia.org: Unexpected >>> error >>> making the query: java.net.UnknownHostException: dbpedia.org >>> at >>> com.hp.hpl.jena.sparql.engine.http.HttpQuery.rewrap(HttpQuery.java:417) >>> at >>> com.hp.hpl.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:358) >>> at com.hp.hpl.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:295) >>> at >>> >>> com.hp.hpl.jena.sparql.engine.http.QueryEngineHTTP.execResultSetInner(QueryEngineHTTP.java:346) >>> >>> at >>> >>> com.hp.hpl.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:338) >>> >>> at jenaclass.main(jenaclass.java:24) >>> Caused by: java.net.UnknownHostException: dbpedia.org >>> at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method) >>> at java.net.InetAddress$2.lookupAllHostAddr(Unknown Source) >>> at java.net.InetAddress.getAddressesFromNameService(Unknown Source) >>> at java.net.InetAddress.getAllByName0(Unknown Source) >>> at java.net.InetAddress.getAllByName(Unknown Source) >>> at java.net.InetAddress.getAllByName(Unknown Source) >>> at >>> >>> org.apache.http.impl.conn.SystemDefaultDnsResolver.resolve(SystemDefaultDnsResolver.java:45) >>> >>> at >>> >>> org.apache.http.impl.conn.DefaultClientConnectionOperator.resolveHostname(DefaultClientConnectionOperator.java:278) >>> >>> at >>> >>> org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:162) >>> >>> at >>> >>> org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:294) >>> >>> at >>> >>> org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:643) >>> >>> at >>> >>> org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:479) >>> >>> at >>> >>> org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906) >>> >>> at >>> >>> org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:137) >>> >>> at >>> >>> org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:118) >>> >>> at org.apache.jena.riot.web.HttpOp.exec(HttpOp.java:1108) >>> >>> >
