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From Benson Margulies <bimargul...@gmail.com>
Subject Re: Jena versus OpenVirtuoso: can I make ARQ work harder?
Date Sun, 22 Jan 2012 19:41:34 GMT
On Sun, Jan 22, 2012 at 2:28 PM, Robert Vesse <rvesse@cray.com> wrote:
> Hi Benson
>
> What version of Virtuoso is this?

It's the latest and greatest. 06.01.3127 and the included Jena driver.

Here's my ignorance on display: I'm passing Syntax.syntaxARQ. I would
expect that, somewhere between ARQ and the virt-jena module, something
would react to a property path by either (a) throwing an exception, or
(b) automatically mapping it to something that works. After all, the
PathParser class exists, why can't I ask ARQ to use it for me?

Instead, ARQ is just normalizing a+ to (a)+. Is the Jena<->store model
predicated on the program writing SPARQL compatible with the target
store's SPARQL?

One of my colleagues has had his head turned by benchmarks that say
wonderful things about Virtuoso, and so I'm trying to find a
relatively painless way to make Virtuoso and TDB swappable in the code
we have, which has various 'modern' SPARQL queries lying about.


>
> OpenLink have been quite slow to move from their proprietary SPARQL extensions to standardized
SPARQL 1.1 syntax.  They never supported any property path syntax in the past and have been
somewhat reluctant to proceed too fast with implementing new SPARQL 1.1 features arguing that
they don't want to give 'standard' features to users that they then have to later remove/alter
(which is ironic given their quantity of proprietary extensions)
>
> Have you tried checking with OpenLink about which versions (if any) support property
paths? Their mailing list for the open source version is virtuoso-users@lists.sf.net

I have pestered their forum, which does not have a good home for Jena
questions.

If there's something a driver can do to provoke ARQ into automatically
doing the moral equivalent of:

  Path path = PathParser.parse("rdf:type/rdfs:subPropertyOf+",
PrefixMapping.Standard);
  String uri = "urn:com.basistech:subprop";
   PathLib.install(uri, path);

I'd cheerfully fork their driver and do the work.


>
> Rob
>
> On Jan 22, 2012, at 10:10 AM, Benson Margulies wrote:
>
>> I was asked to do an experiment with Virtuoso. It looks to me as if
>> ARQ mapped + to (), and then Virtuoso, consistent with its rather old
>> SPARQL dialect, rejected (). Is there any way to tell ARQ what's what?
>> Or is this ipso-facto a bug in the Virtuoso Jena driver.
>>
>> 2012-01-22 12:58:30,042
>> com.basistech.jdd.DocumentDatabaseClientFactory  - JDD ping
>> successful: http://localhost:4460/documentDatabase
>> Exception in thread "main" com.hp.hpl.jena.shared.JenaException: Can
>> not create QueryIterator.:virtuoso.jdbc4.VirtuosoException: SQ074:
>> Line 12: SP030: SPARQL compiler, line 10: syntax error at '(' before
>> 'rdfs:subPropertyOf'
>>       at virtuoso.jena.driver.VirtuosoQueryEngine.eval(Unknown Source)
>>       at com.hp.hpl.jena.sparql.engine.QueryEngineBase.evaluate(QueryEngineBase.java:138)
>>       at com.hp.hpl.jena.sparql.engine.QueryEngineBase.createPlan(QueryEngineBase.java:109)
>>       at com.hp.hpl.jena.sparql.engine.QueryEngineBase.getPlan(QueryEngineBase.java:97)
>>       at virtuoso.jena.driver.VirtuosoQueryEngine$VirtQueryEngineFactory.create(Unknown
>> Source)
>>       at com.hp.hpl.jena.sparql.engine.QueryExecutionBase.getPlan(QueryExecutionBase.java:266)
>>       at com.hp.hpl.jena.sparql.engine.QueryExecutionBase.startQueryIterator(QueryExecutionBase.java:243)
>>       at com.hp.hpl.jena.sparql.engine.QueryExecutionBase.execResultSet(QueryExecutionBase.java:248)
>>       at com.hp.hpl.jena.sparql.engine.QueryExecutionBase.execSelect(QueryExecutionBase.java:94)
>>
>>
>>
>> PREFIX rex:   <http://jug.basistech.com/2011/01/rex-entity#>
>> PREFIX rdfs:  <http://www.w3.org/2000/01/rdf-schema#>
>>
>> # retrieve the URI for each defined relationship
>> SELECT DISTINCT ?r
>> WHERE {
>>  ?r rdfs:subPropertyOf+ rex:relationship .
>> }
>

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