Xesam meta-meta-data spec needs attention.

[Mikkel Kamstrup Erlandsen]

2007/5/4, jamie <jamiemcc at blueyonder.co.uk>:
>
> On Fri, 2007-05-04 at 18:27 +0300, Evgeny Egorochkin wrote:
>
> >
> > This apparently solves the storage issue for this particular case.
> However,
> > there are several shortcomings:
> > 1) Structures are not extensible.
> >       *You cannot define generic structure for an OO language and
> subclass it if
> > necessary.
> >       *Applications can't add custom fields to existing structures.
> > 2) Data retrieval.
> > If you put the whole structure in a single property, you make it hard
> e.g. to
> > use several  files to describe a single structure. Also, it is hard to
> > interlink classes e.g. point to ancestor class(es).
> > If you make all structure nodes e.g. c++ classes high-level nodes just
> like
> > files, you get an issue with node classes which cannot be resolved by
> > introducing node type property due to lack of inheritance.
>
> the struct type is a resource in rdf terminology not a literal so it
> should not have any additional limitations as such. The Child metadata
> can be optional (just as in an rdf schema)  and theres no reason to not
> make it extensible.
>
> We can easily add an Extensible property to the desktop file like :
>
> [Email:Address]
> DisplayName=Email:Address
> Type=struct
> Children=Contact:Name;Contact:Email;
> Extensible=true
>
> where Children are the required members of a struct (this is same as
> having an rdf schema with property minOccurs=1 against them)
>
> I dont see any limitations here - its more a question of nailing down
> what properties of a metadata type are needed to satisfy application
> needs.
>
>
> >
> > and the reason we experience these thoubles is...
> >
> > 3) This approach departs from RDF in the sense that RDF is
> > property-centric(not class defines its properties, but properties define
> > their class) and omits class type information which is quite essential.
> > This quite expectably backfires.
>
> There is class info - the metadata types themselves are classes and you
> can subclass them.
>
>
> > As you can see, implementing e.g. a generic source code browser is
> > problemmatic with this approach.
>
> I dont think so - by supporting struct metadata we can support any
> deeply nested structure just like RDF.


As I just said in another mail - do we really need structs/classes? Won't
the areas needing complex metadata be special cases anyway? Yes they are
cool from a technical standpoint, but what do they bring the end user?


Cheers,
Mikkel
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.freedesktop.org/archives/xdg/attachments/20070505/1daa8a75/attachment.htm