Re: [Tracker] Guessing metadata and retrieval from external resources

[Ivan Frade <ivan frade gmail com>]

Hi,

On Mon, Oct 10, 2011 at 1:33 AM, Age Bosma <agebosma gmail com> wrote:
> Hi,
>
> Would it be an idea to extend this concept by supplementing the metadata
> which could not be determined from a file with info from external
> resources? And/or intelligent guessing for that matter?

Definitely! We had that idea in mind when we designed Tracker. You
just need to implement a miner to calculate or to bring from somewhere
else that information.

> The external and guessed meta-data should be stored separate from the
> normal meta-data stored by Tracker, marked as an external
> title/director/... tag.

We have a limited support for graphs into Tracker that can be used for
that. We use it already to know when certain triplet came from the
file or from an application.

> It is then up to an application to decide what to use. I.e. normal title
> present? Use it. No title present but an external title present? Use
> that one if you like.

That is nice in theory, but in practice means the application must do
multiple queries just for the title. Also, the application needs to
know how many different sources of information are available.

 I would say that those "scrapping miners" should override the values
of the properties they know. In some cases we could add new properties
to the ontologies and the application could use "tracker:coalesce" in
the query.

> Does functionality as described above fit within the goals/scope of tracker?
> Would there be any objections again going into this direction?
> Does tracker allow extending functionality as described above?

 It fits very nicely with our vision of Tracker. You just need to
implement a miner (check libtracker-miner) and use the graphs wisely
to put the information into Tracker. Of course it is the first time
anybody writes a "scrapping miner", so maybe we need to fix details
here and there. Business as usual.

 Note that probably these new miners would need some UI (to ask the
user what movie from a list is the one in their filesystem). This can
be tricky (no miner has specific UI so far).

> Does the current shared-filemetadata-spec provide a way to store
> information as external/additional?

 That spec is completely out-of-date. The model we are actually using is here:
http://developer.gnome.org/ontology/unstable/

 The documentation about libtracker-miner is here:
http://developer.gnome.org/libtracker-miner/unstable/

 And you will need to use also libtracker-sparql:
http://developer.gnome.org/libtracker-sparql/unstable/

 If you need a more interactive help, feel free to come to IRC
(#tracker in GIMPnet) and ask!

 Regards,

Ivan