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From Simon Wibberley <simon.wibber...@sussex.ac.uk>
Subject Re: Unexpected end of input errors on reading from dbpedia
Date Tue, 08 Feb 2011 14:23:19 GMT
Building from ARQ SVN worked a treat! 

Thanks very much for your response Andy.

Best,

Simon

On 8 Feb 2011, at 13:37, Andy Seaborne wrote:

> Simon,
> 
> Thanks for a complete, minimal example.  I get the same error.
> 
> I suspect it's not woodstox per se, but a lower level networking issue because I can
get things to work by reading the data as fast as possible.  Maybe woodstow's use of the inputstream
is seeing the connection close flag without making sure there isn't more data to read.
> 
> The code in ARQ SVN has a workaround for this - it slurps up the network bytes as fast
as possible, then passes them to woodstox; woodstox is not then working over the network input
stream but instead a ByteArrayInputStream.
> 
> (An alternative, I tried was adding a buffering layer to the input stream but that didn't
work).
> 
> 	Andy
> 
> On 07/02/11 23:09, Simon Wibberley wrote:
>> Hi there,
>> 
>> I'm trying to query dbpedia for a list of company names. I'm
>> inconsistently getting WstxEOFException's caught by jena, which then
>> raises a ResultSetException. This happens after some data has been read
>> successfully. Following the tcp stream in wireshark shows a complete
>> response from the dbpedia server.
>> 
>> Is this a bug in woodstox? I've tried replacing the libs with wstx4 and
>> stax2, but same error occurred. Is there anything I'm doing wrong/badly
>> with jena/sparql? (I'm relatively new to this). The minimal test case
>> below seems to reproduce the error (output also below) reliably. I've
>> tried this on both windows7 and OS X 10.6 from different locations.
>> Could you check to see if you get the same error?
>> 
>> Any ideas?
>> 
>> Many thanks,
>> 
>> Simon Wibberley
>> 
>> import com.hp.hpl.jena.query.Query;
>> import com.hp.hpl.jena.query.QueryExecution;
>> import com.hp.hpl.jena.query.QueryExecutionFactory;
>> import com.hp.hpl.jena.query.QueryFactory;
>> import com.hp.hpl.jena.query.QuerySolution;
>> import com.hp.hpl.jena.query.ResultSet;
>> import com.hp.hpl.jena.rdf.model.RDFNode;
>> 
>> public class TestJena {
>> public static void main(String[] args) {
>> 
>> String queryString = "PREFIX rdf:
>> <http://www.w3.org/1999/02/22-rdf-syntax-ns#>"
>> + "PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>"
>> + "SELECT ?var "
>> + "WHERE { ?var rdf:type dbpedia-owl:Company . }";
>> 
>> Query query = QueryFactory.create(queryString);
>> 
>> QueryExecution qexec = QueryExecutionFactory.sparqlService(
>> "http://dbpedia.org/sparql", query);
>> ResultSet rs = null;
>> 
>> rs = qexec.execSelect();
>> qexec.close();
>> 
>> while(rs.hasNext()) {
>> QuerySolution sqs = rs.next();
>> RDFNode node = sqs.get("var");
>> System.out.println(node);
>> }
>> }
>> 
>> 
>> }
>> 
>> com.ctc.wstx.exc.WstxEOFException: Unexpected EOF; was expecting a close
>> tag for element <uri>
>> at [row,col {unknown-source}]: [106,47]
>> at com.ctc.wstx.sr.StreamScanner.throwUnexpectedEOF(StreamScanner.java:686)
>> at
>> com.ctc.wstx.sr.BasicStreamReader.nextFromTree(BasicStreamReader.java:2730)
>> at com.ctc.wstx.sr.BasicStreamReader.next(BasicStreamReader.java:1019)
>> at
>> com.ctc.wstx.sr.BasicStreamReader.getElementText(BasicStreamReader.java:669)
>> 
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.getOneSolution(XMLInputStAX.java:480)
>> 
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.hasNext(XMLInputStAX.java:216)
>> 
>> at sw206.TestJena.main(TestJena.java:31)
>> Exception in thread "main"
>> com.hp.hpl.jena.sparql.resultset.ResultSetException: XMLStreamException:
>> Unexpected EOF; was expecting a close tag for element <uri>
>> at [row,col {unknown-source}]: [106,47]
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.staxError(XMLInputStAX.java:510)
>> 
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.hasNext(XMLInputStAX.java:220)
>> 
>> at sw206.TestJena.main(TestJena.java:31)
>> Caused by: com.ctc.wstx.exc.WstxEOFException: Unexpected EOF; was
>> expecting a close tag for element <uri>
>> at [row,col {unknown-source}]: [106,47]
>> at com.ctc.wstx.sr.StreamScanner.throwUnexpectedEOF(StreamScanner.java:686)
>> at
>> com.ctc.wstx.sr.BasicStreamReader.nextFromTree(BasicStreamReader.java:2730)
>> at com.ctc.wstx.sr.BasicStreamReader.next(BasicStreamReader.java:1019)
>> at
>> com.ctc.wstx.sr.BasicStreamReader.getElementText(BasicStreamReader.java:669)
>> 
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.getOneSolution(XMLInputStAX.java:480)
>> 
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.hasNext(XMLInputStAX.java:216)
>> 
>> ... 1 more
>> 22:59:25,250 WARN XMLInputStAX$ResultSetStAX:73 - StAX error:
>> XMLStreamException: Unexpected EOF; was expecting a close tag for
>> element <uri>
>> at [row,col {unknown-source}]: [106,47]
>> com.ctc.wstx.exc.WstxEOFException: Unexpected EOF; was expecting a close
>> tag for element <uri>
>> at [row,col {unknown-source}]: [106,47]
>> at com.ctc.wstx.sr.StreamScanner.throwUnexpectedEOF(StreamScanner.java:686)
>> at
>> com.ctc.wstx.sr.BasicStreamReader.nextFromTree(BasicStreamReader.java:2730)
>> at com.ctc.wstx.sr.BasicStreamReader.next(BasicStreamReader.java:1019)
>> at
>> com.ctc.wstx.sr.BasicStreamReader.getElementText(BasicStreamReader.java:669)
>> 
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.getOneSolution(XMLInputStAX.java:480)
>> 
>> at
>> com.hp.hpl.jena.sparql.resultset.XMLInputStAX$ResultSetStAX.hasNext(XMLInputStAX.java:216)
>> 
>> at sw206.TestJena.main(TestJena.java:31)
>> 
>> 
>> 
>> 


--
Simon Wibberley
DPhil Student

Machine Learning and Computational Linguistics
Chichester 1, R203
Informatics
University of Sussex
Brighton, UK
simon.wibberley@sussex.ac.uk




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