[Nepomuk] SPARQL construct queries in Soprano with Virtuoso

[Sebastian Trüg]

On 05/07/2010 10:55 AM, Ilkka Laukkanen wrote:
> On Thu, May 6, 2010 at 7:03 PM, Sebastian Trüg <trueg at kde.org> wrote:
>> I tried the query here and I got a graph. Could you monitor stderr for
>> error messages, please?
> 
> I'll document exactly what I did here for reference:
> 
> Terminal 1:
> 
> $ sopranod --backend virtuoso --storagedir /var/tmp/soprano # there's
> a db there that has a bunch of stuff
> Using Virtuoso Version: "6.1.1.3127-pthreads"
> Listening on port  5000
> void Soprano::VirtuosoController::writeConfigFile(const QString&,
> const Soprano::BackendSettings&) "/tmp/virtuoso_TJ8638.ini"
> Starting Virtuoso server: "/usr/local/bin/virtuoso-t" ("+foreground",
> "+configfile", "/tmp/virtuoso_TJ8638.ini", "+wait")
> (...the rest of the virtuoso messages...)
> Virtuoso started: 8646
> Soprano::ODBC::Connection::Connection()
> Soprano::Server::DBusController(0x25e3d80)
> virtual Soprano::ODBC::Connection::~Connection()
> Soprano::Server::DBusController(0x25e3d80)
> Soprano::ODBC::Connection::Connection()
> Soprano::Server::DBusController(0x25e3d80)
> Connecting to deprecated signal
> QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)
> 
> Terminal 2:
> 
> $ sopranocmd --dbus org.soprano.Server --model main query "$(cat
> myquery.sparql)" # myquery as documented in earlier email
> fmtaggret- -> "@prefix rdfs:\t<http ....etc
> 
> The result is the same as it was through the API. I'm not sure what a
> graph query result through sopranocmd should look like though?
> Probably not like that?

It looks exactly like a "list" command output, so basically a bit like
NTriples.

> Poking around, I also tried
> 
> $ sopranocmd --dbus org.soprano.Server --model main --serialization
> rdfxml query "$(cat myquery.sparql)"
> Can only serialize graph queries
> 
> That error message is very interesting. How is my construct query not
> a graph query?

same problem. There is a problem when converting the return result into
a graph. Thus, a bindingset is returned. :(

Could you give me the database so I can try to recreate the situation?

Cheers,
Sebastian