Dear all,
please find attached my comments to the Char DM.
I am not sure I am popping at the right time in this case (Mireille's
mail does not say whether it did go to the TCG already or otherwise)
so please forgive me if I am at the wrong timing.
Characterisation Data Model comments
The concepts in the document apply very well to the description
(Characterisation) of, for instance, an observation. There is a
clever separation into axes with different properties, which makes
the complete characterisation possible with few parameters. For
instance, the table in page 9 is very useful to identify correctly
the concepts for a proper description of a "data set". The figure 2
on the different levels of description is also very enlightening.
There are some points however that,not being showstoppers for the
Recommendation process, should be considered for improvement, whether
in this version or subsequent ones. Other issues are probably more
editing than any other thing.
- in pg.3 reference is done to the Observation DM. However, it looks
like not much work has been going on on the Observation DM. Is the
Observation DM going to go ahead, or is it going to be "superseded"
by the Characterisation DM globally?. In the former case (Obs DM
disappearing), the Char DM should contain all the info that is
currently on the Obs DM. In the latter, the difference (or
complementarities) between the two should be briefly mentioned.
- in pg. 10 (point 3.4.1) mention is done to a combination of UCD and
units to "ensure uniqueness and recognition by standard software".
This issue has been treated many times, and at the last Beijing
meeting it was finally recognised that a set of "BIYECTIVE UTYPES"
should be defined for Data Models to be understood. This biyective-
utypes were given the name "UFIs" by Jonathan. Despite the fact that
they are undefined yet, they resemble _very closely_ the Object
Oriented technology attribute naming, i.e., names constructed by dots
in between class names. The issue of how to mention actions in the
UFIs is also an important issue and a small team has been created to
deal with these things (although admittedly, not started to work on
it yet). Therefore, this paragraph should either contain a reference
to that, or remove the first paragraph.
- the whole list of attributes in the Data Model should be clearly
made explicit in the document. They should normally correspond to
what has been called UTypes during all this time, and they should be
inside the document, and not in a separate one. In particular, the
UTypes should clearly reflect the UML structure of the DM. The UML is
missing a "top level" diagram, where inheritances and associations
are clearly seen. Also, the "Axis vs Properties" issue can be solved
through proper UML modeling of the DM, and should be done so, in my
opinion. Leaving the possibility to traverse the tree upside down
(Axis to Properties) or the other way around might make the model
unworkable for software handling. The UML and its attributes should
be reviewed.
- mention is done in 4.4 of the Quantity DM. In my understanding, the
Quantity DM effort has been discontinued by the DM group. If this is
the case, the reference should be removed. Otherwise, a more detailed
reference of how the Quantity DM is affecting this document should be
made explicit.
- point 5.2 goes again to the UType creation. UTypes (or UFIs in our
more "modern" view after Beijing) should not have repetitions in
their names. Different model classes don't need to have the name of
the parent in their name. In any case, the whole list of the UFIs (or
UTypes) should be given in the document with a clear mapping 1 to 1
to the UML diagram that represents them. The Spectral DM could be a
good example of how this can be done.
That's all.
Cheers,
P.
On Jul 5, 2007, at 3:15 PM, Mireille Louys wrote:
> Dear IVOA members,
>
> The RFC period for comments for the Characterisation Data model
> ended yesterday, after 5 weeks .
> This Data Model took quite a long time to get mature, and has been
> presented in Interop meetings at
> different stages.
> People interested gave their comments and provided good hints all
> along the different development phases.
>
> Its scope has been divided to provide two versions of the Model:
> - the current 1.11 version for data queries and all purpose data
> analysis
> - the next version will describe more refined metadata for complex
> observations, sensitivity functions,
> resolution variations , etc...
>
> Comments on the RFC page are not numerous but I do not want to
> delay the
> recommendation process any longer.
>
> It is time for me to pass it to the TCG group to review the document.
>
> Thanks ,
> Mireille Louys, DM Chair
>
>
> --
> --------------------------------------------------------------
>
> Mireille LOUYS mailto: Mireille.Louys-at-astro.u-strasbg.fr
>
> L S I I T & CDS,
> Ecole Nationale Superieure Observatoire de Strasbourg
> de Physique de Strasbourg, 11, Rue de l'Universite
> Boulevard Sébastien Brant, BP 10413 67000 STRASBOURG
> 67412 ILLKIRCH Cedex Tel: +33 3 90 24 24 34
> ---------------------------------------------------------------
>
>
>
Pedro Osuna Alcalaya
European Space Agency (ESA)
European Space Astronomy Centre (ESAC)
Research and Scientific Support Department (RSSD)
Astronomy Science Operations Division (SCI-SD)
e-mail: Pedro.Osuna-at-esa.int
Tel + 34 91 813 13 14 Fax: +34 91 813 11 72
European Space Astronomy Centre (ESAC)
P.O. Box 50727
E-28080 Villafranca del Castillo
MADRID - SPAIN
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Received on 2007-07-10Z19:00:21