[Image Data Model]was Re: roadmap 2010-2011

[Patrick Dowler]

On Thursday 16 September 2010 09:31:27 Mireille Louys wrote:
> I think ObsCoreDM already covers the need to describe an image.

> I do not see the point in developing one DM for each kind of data product.
> Lightcurves description can benefit of the description of the
> Characterisation axes, and this the same for TimeSeries, from my point
> of view.

That sounds great and should promote the kind of consistency and re-use that 
we need. I mentioned ImageDM but hoped this would be the answer.

Do you envision that the SpectrumDM will be superceded by the more general 
ObservationDM (at some point)?

> Each model can be reused partly, not all axes are mandatory, and so
> derived representations can be defined and serialised either in XML or
> in VOTable.

At some point, someone has to define this derived model. Is that then the 
responsibility of the application? For example, following the thread above, 
would a future SSA 2.0 refer to the ObservationDM and SSA would specify 
requirements and restrictions that capture the "use of the model"? That seems 
consistent with current use of data models in DAL.

If a specific application needed some additional detail that was not covered in 
the model, could it extend the model somehow? should it? or should these 
things always be folded back into the main Observation DM? I don't have any 
specific examples for such a scenario, but it seems bound to happen due to us 
all not being 100% precogniscient or simply because a very specific part has no 
general use and never makes it into the general model (which is tougher). More 
curious how you see this being handled...



-- 

Patrick Dowler
Tel/Tél: (250) 363-0044
Canadian Astronomy Data Centre
National Research Council Canada
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Conseil national de recherches Canada
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