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

[Mireille Louys]

Dear Pat, Dear all,

I think these questions are very relevant to think about how we should  
organise the data modeling effort. One one hand, we wish that what has  
been done will not be thrown away and will feed a general stable  
construction. On the other hand we need new ideas to show up  in order  
to cover new use-cases, formalized in specific contexts like  
Timeseries or LightCurves.
I understand it is good to explore new models and also good to  
stabilize them in a more general model like the future Observation  
Data Model.

May be it is just a pb of re-usability rules and convergence checking  
but may need some man power.

More comments in the text below.

Thanks for your inputs, Mireille

Patrick Dowler <patrick.dowler at nrc-cnrc.gc.ca> a écrit :

> 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 Do you envision that the SpectrumDM will be superceded by the more general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)?
>
yes , ObservationCoreComponents DM already includes a lot of the  
defined structures produced in Spectrum DM.

>> 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.
Yes , I agree.

> 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...

I guess applications that need to extend a version of an IVOA data  
model should publish their usage of the model with their added parts.
If this is common enough with other implementations , the general  
model can be revised to include or update new items.


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> Patrick Dowler
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