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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 14:10:03 GMT
> What version of woodstox?

3.2.9 and 4.1.1 I believe.

Simon

> On Tue, Feb 8, 2011 at 8:37 AM, Andy Seaborne
> <andy.seaborne@epimorphics.com> 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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