Revised ImageDM-ObsCore architecture

[Laurino, Omar]

Doug,

On Wed, Nov 13, 2013 at 8:10 PM, Douglas Tody <dtody at nrao.edu> wrote:

> So for example the Observation may be described, and a
> "package" can be downloaded containing multiple data products.  Or the
> individual datasets (data products) may be exposed, linked by a common
> obs_id.  Or some combination of the two.
>

This is interesting, even though I believe it needs some clarification
regarding the "combination of two", which makes the description somewhat
fuzzy.

I believe neither Mark's nor your diagrams capture this, which calls, at
the very least, for Observation having a collection of 0..* Datasets, as
opposed to either being a generalization of Dataset or containing a single
Dataset.

Regarding your comment on the specialization of Observation vs ObsCore:
specialization works exactly this way: a 'car' is a specialization of a
'vehicle', i.e. it has all the features of a vehicle, plus more stuff, so
it is larger.
See for example this:
http://understandingrdbms.blogspot.com/2013/04/data-model-part-2-specialization.html

However, I agree that this distinction between Observation and ObsCore is
kind of funky and probably unnecessary, and I know that others share this
opinion as well.

However, this is what ObsCore calls for: it is clearly stated in the
document that ObsCore is... ahem... a core model, part of an unspecified
larger Observation Model.

Since we can probably represent this funky statement in a technically
formal and consistent way, we can try to do it, so that we don't need to
change the current definition of ObsCore.

Omar.




-- 
Omar Laurino
Smithsonian Astrophysical Observatory
Harvard-Smithsonian Center for Astrophysics
100 Acorn Park Dr. R-377 MS-81
02140 Cambridge, MA
(617) 495-7227
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