[Nepomuk] Question about Nepomuks caching mechanism

[Jörg Ehrichs]

Hi all,

I have a small question regarding the caching mechanism in the current
KDE 4.11 Nepomuk implementation.

In Conquirere I use Nepomuk as my data storage to show and manipulate
the connections between the nfo:Document and nbib:* Nepomuk resources.

This works like a charm and is blazing fast when I display available
as well as new resources. Now Nepomuk added a caching mechanism, while
I save the retrieved Nepomuk2::Resources to display them in my
application.

When I start to add changes and send them via Nepomuk2::setProperty I
can observe the changes via the resourcewatcher. I do get the correct
updates via:

propertyChanged (const Nepomuk2::Resource &resource, const
Nepomuk2::Types::Property &property, const QVariantList &addedValues,
const QVariantList &removedValues)

and I can see the updated property and its value, but the resource is
still a cached one with its old values, even with several updates I
won't get any changes in the Nepomuk2::Resources until I restart the
application.

I've seen there is a new method .setWatcherEnabled(true) but it does
not seem to have the desired effect.

In former versions I could get an updated Nepomuk2:Resource by using a

QEventLoop loop;
QTimer::singleShot( 1000, &loop, SLOT(quit()) );
loop.exec();

as mentioned in bug: 306108
this however does not seem to work anymore.

Now the question. How is the design meant to work?
Is it possible to force the update of Nepomuk resources without
getting the cached ones? As of now even creating a new
Nepomuk2::Resource based on the uri returns a cached one.
Or is the Nepomuk storage design to be a fast lookup/search for
existing data and I should rather copy the data into a local storage
and update this via the propertyChanged signal from the
ResourceWatcher?

Any help with this is very appreciated, as I'm currently lost what the
"best practice" in such a situation is. I like to avoid keeping my own
database that pushes data to nepomuk the way akonadi is handling it
with the mails/events.

Kind Regards,
Joerg