Xesam meta-meta-data spec needs attention.

[Mikkel Kamstrup Erlandsen]

2007/5/12, Fabrice Colin <fabrice.colin at gmail.com>:
>
> Hi all,
>
> On 5/12/07, Joe Shaw <joe at joeshaw.org> wrote:
> > I haven't been following this thread super closely.  Why define these
> > in .desktop-like files rather than in some sort of documented
> > specification?  Code is what ultimately will be setting these, so it
> > will have to obey them.
> >
> I agree.
>
> I am not sure I understand the benefit of defining these in some sort
> of user-editable configuration, instead of in a spec.
> If the user defines a new field, it won't have any effect as the engine
> has
> no way to automagically know how that new field maps to the underlying
> file format. The corresponding metadata extractor will have to be updated
> to support the new field and make sure it is retrieved from files.


It was not the idea that an ordinary user should install field definitions.
Applications with special needs could do so, but most wouldn't need to. Do I
understand correctly in that you don't see the need to have the ontology
defined in a machine readable way? Just specced out in some document? While
this could be done, the machine readable ontology does have quite a few
benefits. Fx:

 * You could update the ontology without updating any applications or search
engine code

 * Applications could create dynamic guis that reflects the ontology

 * 3rd parties could extend the ontology by installing their own ones


Ok let me explain why I personally prefer the .desktop like approach given
that we install the ontology on the hard drive in a machine readable way...

1) It doesn't introduce dependencies on new 3rd party libs (maybe it does
for qt/kde I'm uncertain on their situation). GLib has really good support
for .desktop files (with i18n which we need too) in what is known as the
keyfile api. A rdf parser is likely to require either a good deal of code in
libxesam or a 3rd party lib. 3rd party libs are a big deal we shouldn't
accept with out a great deal of thought.

2) Application developers can easily create their own ontologies. Anybody
can understand the .desktop approach by looking at one or to field
definitions. That is not necessarily the case with rdf.

3) Although RDF has (relatively) simple representations it might scare
developers of by pure reputation.

4) .desktop is already a de facto standard on the desktop (and xesam is all
about the desktop). RDF is a standard, but it's not greatly used in desktop
applications.

5) RDF is extensible to just about any point imagnable, while this is
normally good, I think it would be healthy to restrict our selves to some
extent, so that we don't fly of into abstraction space.

6) If it turns out eventually that .desktop is too simple, it would be
possible to allow rdf ontologies as well. It would not be the most beautiful
solution, but I think it is acceptable.

Cheers,
Mikkel
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