Re: Intrinsic vs extrinsic metadata (my action #54)

Hi Andrea,

Thank you for your valuable comments on this discussion about metadata.

I used the diagram just to help the understanding (and not as a formalism),
but I think this is not the case. So, the discussion can continue based on
the textual descriptions.

I think we are still on the discussion stage and later on the WG may decide
how to present this information to the readers. I agree with you that we
should be careful with overspecifications.

kind regards,
Bernadette






2014-07-12 18:46 GMT-03:00 Andrea Perego <andrea.perego@jrc.ec.europa.eu>:

> Dear Bernadette,
>
> Thanks a lot for considering so carefully my comments.
>
> I understand that there's a discussion on the WG on the level of
> formalisation to be adopted. So, unless you think otherwise, I guess
> it would be more appropriate for me to avoid further comments on the
> diagram until the WG takes a decision. Actually, I understand the
> point made by Antoine. Personally, I'm not a fan of overspecification,
> especially when working on resources meant for re-use (as
> vocabularies), since it is impossible to foresee all present and
> future use cases.
>
> Meanwhile, I'll keep following your discussion with the greatest interest.
>
> Cheers,
>
> Andrea
>
>
> On Fri, Jul 11, 2014 at 5:20 PM, Bernadette Farias Lóscio
> <bfl@cin.ufpe.br> wrote:
> > Hi Andrea,
> >
> > Thanks again for your comments and for being part of this discussion!
> > Please, find some more comments below:
> >
> >> >> 2. From the diagram it is not clear if some metadata elements are
> >> >> specific to data, datasets or their distributions, or, rather, they
> can be
> >> >> used for all of them. E.g., "access metadata" are just for
> distributions or
> >> >> also for data/sets?
> >> >
> >> > The initial idea was to identify metadata to describe datasets. I
> >> > included access metadata is part of the classification, but I'm not
> sure if
> >> > this type of metadata should be used to describe datasets or
> distributions.
> >> > Moreover, it is not clear for me what types of metadata should be
> used to
> >> > describe the distributions. For example, should we use the same ones
> that we
> >> > use to describe datasets?
> >>
> >> IMHO, this depends on how the different entities are defined. E.g.,
> >> supposing that the notions of dataset and distribution correspond to
> >> the ones defined in DCAT, access metadata concern distributions - a
> >> dataset is an abstract entity, you can access just its representations
> >> - or manifestations, using the FRBR terminology.
> >
> >
> > I agree with you Andrea! Dataset is an abstract entity and it makes more
> > sense that distributions have access metadata instead of the dataset
> itself.
> > However, I think that we can keep the metadata hierarchy proposed in the
> > diagram of [1]. Then, later on we need to identify what type of metadata
> > concerns datasets or distributions.
> >
> >>
> >> >> 3. I wonder whether structural metadata are meant to describe only
> the
> >> >> structure (database schema) or also the content (database instances)?
> >> >> Actually, in VoID structural metadata are doing both.
> >> >
> >> > Structural metadata should describe the data itself. They should
> provide
> >> > an interpretation for the dataset content (i.e. the data). It can be
> seen as
> >> > the vocabulary (ontology) that describes the data. I think this idea
> is
> >> > different from the structural metadata proposed by VOID. If you have
> a RDF
> >> > distribution for a given dataset, maybe you can have a VOID
> description for
> >> > this specific distribution.
> >>
> >> I see the point. So, the description is only intensional (i.e., about
> >> the characteristics of the entities in the dataset), or also
> >> extensional (e.g, how many entities are in the dataset, and which are
> >> such entities)?
> >
> >
> > Yes, in this case is only intensional. Information about the number of
> > triples is specific for RDF distributions, and it should be part of the
> > metadata that describes the distribution. Does it make sense for you?
> >
> >>
> >> >> 4. The diagram does not model the fact that metadata are, in turn,
> >> >> data. As such, metadata records may be available in different formats
> >> >> (metadata distributions) and they can be described by other metadata
> (this
> >> >> scheme is, in theory, recursive). A real world example is given by
> INSPIRE
> >> >> [1], where we have "metadata on metadata", providing information
> concerning
> >> >> the provenance of a metadata record (responsible, language,
> >> >> creation/publication/modification dates).
> >> >
> >> > Yes, this is a good observation! I agree that metadata itself may have
> >> > some properties (metadata) . Maybe, we can consider that these
> properties
> >> > will be associated to the class metadata and will be inherited by the
> >> > sublasses. Does it make sense for you?
> >>
> >> I was thinking that, in order to model this, it might be enough to
> >> make metadata as a subclass of entity "data". This would also model:
> >> - the "recursive" nature of metadata (i.e., in theory, you may have
> >> metadata on metadata, which in turn can be described by other metadata
> >> and so on);
> >> - the fact that, as data, also metadata have distributions.
> >>
> >
> > I was trying to represent this in the diagram, but it is not easy. I
> > considered metadata as a subclass of data, so both data and metadata may
> > have different distributions. However, I consider that the dataset
> itself is
> > decribed by metadata not the data. In this case, we need another
> association
> > to represent that metadata is also described by metadata. I attached the
> pdf
> > version of the diagram together with the ppt. Please, let me know what do
> > you think and fell free to make modifications.
> >
> > Thanks again!
> > Bernadette
> >
> >
> >>
> >> Cheers,
> >>
> >> Andrea
> >
> >
> >
> > [1] http://lists.w3.org/Archives/Public/public-dwbp-wg/2014Jul/0006.html
> >
> >
> >
> > --
> > Bernadette Farias Lóscio
> > Centro de Informática
> > Universidade Federal de Pernambuco - UFPE, Brazil
> >
> ----------------------------------------------------------------------------
>
>
>
> --
> Andrea Perego, Ph.D.
> European Commission DG JRC
> Institute for Environment & Sustainability
> Unit H06 - Digital Earth & Reference Data
> Via E. Fermi, 2749 - TP 262
> 21027 Ispra VA, Italy
>
> https://ec.europa.eu/jrc/
>
> ----
> The views expressed are purely those of the writer and may
> not in any circumstances be regarded as stating an official
> position of the European Commission.
>



-- 
Bernadette Farias Lóscio
Centro de Informática
Universidade Federal de Pernambuco - UFPE, Brazil
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