[QUANTITY] Data Model for Quantity v0.5

[Francois Bonnarel]

Hi Jonathan, Data modelers
    Do I still have to answer to this one after the email avalanche?
But my time scale is somewhat larger the usual one in this list!

see you soon all!
François

<From owner-dm at eso.org  Mon May 10 16:06:56 2004
<Date: Mon, 10 May 2004 10:10:43 -0400 (EDT)
<
<Here I try and summarize my understanding of the comments on the OBS and Q
<models, with a few replies by me. I have made minor updates to obs.tex/ps/pdf
<and qty.tex/ps/pdf on hea-www.harvard.edu/~jcm/www/vo/docs 
< - Jonathan
<
<OBS:
<
<Bonnarel and Louys proposed a Packaging section. After minor
<editing I've included it in Obs.tex.
<
<[But I think we need more than this: if we are to have an XML wrapper
<of FITS data, we need to have a way of identifying *parts* of the FITS
<file with metadata in the XML - a FITS path like XPATH which can
<be tied to XML elements or UTYPE entries.]
<
---> You are right: what we missed more generally is a link to values
description, which includesd file paths, URL, URL templates, and more
complex features like the one you describe.
      By the way, in the last version of the document you added the 
personal note that link between an observation and "subobservation" is
not in the right place in Packaging. I am convinced now. The right place
for "Observation reentrance"  which can manage an HST Association/member
relationship is probably in a specific box somewhere in provenance.
Something close to what Anita did with Composition.



<Gerard: need for identifiers for datasets. 
<
<[Yes, I think we should just use the one developed by the journals,
<which is being adopted by the registry group]
<
<Gerard: data trees as only one possible view of the archive complexity.
<
<Gerard: change name of Provenance to Experiment (can other people vote
<on this please?)
<

-----> I was happy with provenance.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
<Anita: Radio DM draft - bravo! Will reply in detail on this one soon.
<
<QTY:
<
<Suggested approach changes:
<
<- Don't have a Q container model at all, every piece of data is its
<own class with a corresponding definition in the schema. (Hill)
<
<- Build bicycles not jet fighters (Micol and Didelon).
<
<[I concede that Q is rather complicated. But it does provide a nice path
<from the rather simple BasicQ, which does what Pierre et al. want, to
<the fancy StdQ, which does the jet fighter job. I think Brian's
<message today did a good job of summarizing the model, and we
<need something like this early on in the doc. I agree with David that
<existing astronomy systems are rather complicated and a too-simple model
<will not be able to interface with them. I believe that elaboration of
<the Observation model and its detailed application to real archival
<datasets will quickly lead us to using some of the fancier features of
<Q. In general though I think that computer scientist/programmers will 
<understand Q, and VO data center astronomers will work mostly with
<Observation and some specialized things derived from Q that Observation
<will need. The programmers will eventually be happy with the elegance 
<that all of the specialized things are just different forms of Q. If I'm
<right, this will fall out when we continue work on Observation and
<particularly on its serialization, so I'm hoping we can discuss that in
<the next couple of weeks prior to Interop.]
<
<Suggested model changes
<
<- I haven't seen any specific proposed changes to the Q model itself,
<  beyond suggestions that the whole idea is silly.
<
<Suggested serialization changes:
<
<- Array values tagged rather than space-separated (Hill)
<
<Documentation:
<
<- More detailed explanation of Phenomenon concept (Hill)
<- More astronomy language and less computer language (Micol)
<
<
<What have I missed?
<

=====================================================================
Francois   Bonnarel               Observatoire Astronomique de Strasbourg
CDS (Centre de donnees          11, rue de l'Universite
astronomiques de Strasbourg)    F--67000 Strasbourg (France)

Tel: +33-(0)3 90 24 24 11       WWW: http://cdsweb.u-strasbg.fr/people/fb.html
Fax: +33-(0)3 90 24 24 25       E-mail: bonnarel at astro.u-strasbg.fr
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