[Kde-pim] [Akonadi] Virtual Collections

[Eduardo Robles Elvira]

2009/9/9 Volker Krause <vkrause at kde.org>:
> Hi,
>
> so, yet another mail about that topic, since we still haven't got a solution
> yet that covers all our needs. Unlike Steve though, I've not writing a very
> long mail but a very long wiki page ;-)
>
> See http://techbase.kde.org/Projects/PIM/Akonadi/VirtualCollections
>
> It's mainly a summary of previous discussions about that topic to gather all
> the requirements as well as the solutions Steve and I have come up with so
> far. Some of it sounds scary, but luckily that's mostly implementation
> details API users will never notice. It also contains a plan on how to
> implement all that.
>
> Feedback would be very welcome. Are all your use-cases covered? Any ideas on
> how to simplify/improve the design?
>
> regards
> Volker

Hello Volker!

Sorry for the late answering, I'm at the moment quite busy with the
september exams (I'll finish the 21th). I've read the whole wiki and
it seems that konqueror bookmarks is not the only case anymore in
akonadi where the backend for storing the data is Nepomuk itself, now
that we have the Tag resource (which I didn't know it existed anyway
previously).

If I understand correctly, the idea is to have virtual collections in
a different resource than the one used for non-virtual collections? I
don't really see the need for that. Also, I don't understand very well
the difference between physical virtual resources and virtual virtual
resources :P

As an use case for virtual resource we could have Konqueror bookmarks.
There you want to have virtual collections like "most visited
websites", "recently added bookmarks" or "unclasified bookmarks". Also
you want the awesome bar to search bookmarks. For searching bookmarks
in the awesomebar I maintain a bookmarks model and a custom filter
proxy model, which is probably faster/more efficient than creating a
virtual collection, modify the query on the go depending on the user
input and watch changes in the virtual collection.

But for virtual collections like those I mentioned probably a
persistent search query would fit best. So for search I would suggest
using Nepomuk and for the query language those nepomuk supports
(Sparql?). I've got the nepomuk sparql queries for some of those
virtual folders but last time I checked the search folders were not
working to me. Anyway, I would like to let the user put those search
queries wherever in the hierarchy of the bookmarks resource he wants,
and currently Akonadi doesn't support that.

For me, a compromise solution would be to put a placeholder folder
saying "here goes the recently added bookmarks virtual collection" and
then manually put it there in my bookmarks model. This would let the
user put the virtual collection in multiple places if he wants .This
is what I plan to do at the moment (when I get search collections
working again), but perhaps we could come up with a better solution
within Akonadi itself?

Anyway thanks for your work Volker =)

Greetings
    Eduardo Robles Elvira.
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