[Nepomuk] When is a Nepomuk::Thing stored?

[Christian Mollekopf]

Hi,

I have a small issue where I seem to lose the groundingOccurence (Resource) of 
a Thing.

I'm working with akonadi::items of which i create resources like this:

Nepomuk::Resource res( item.url() );

of this resource i retrieve the thing via:

Nepomuk::Thing thing = res.pimoThing();
thing.addType(Nepomuk::Vocabulary::PIMO::Task());

This thing is then used for tagging and stuff.

Now I added a feature which converts an akonadi todo into an akonadi note, 
which means the resource changes but all the tags should remain.
For this i delete the old akonadi item and create a new one of the new type, 
which makes of course the old Resource invalid.
So that I can keep all Nepomuk relations I just wanted to assign the new 
resource to the old thing like this:

oldThing.addGroundingOccurrence(newResource);

This works fine on the first look, but when I restart the program all the tags I 
assigned vanished. 
Is there something else which I need to do so the new groundingOccurrence of 
the thing is synced to the RDF store?

I don't really understand when the data is stored, but so far I just assumed 
this happens instantly and all worked well so far...

Cheers,

Chris