[QUANTITY] Data Model for Quantity v0.5

[Martin Hill]

Pierre Didelon wrote:

> Yes, and previous experience in astronomy was astrores
> (http://cdsweb.u-strasbg.fr/proj/astrores.htx), which more or less
> give birth to VOTable, and ASU (http://vizier.u-strasbg.fr/doc/asu.html),
> which AFAIU was "adapted" for cone search and so.
> But improvement to this "pre-bicycle stage" must be performed, and
> IMHO one major goal of Quantity would be to procure support
> for this kind of problematic : ability to transmit simple parameters
> sufficiently described (inside the VO frame).
> It is why I feel that XML serialization is the most important
> part of Quantity.

I agree with this - it's how we pass values around, describe them and 
structure them that is important (as you know I think VOTable falls far 
short of the mark in doing this sufficiently well for inter-VO-service 
messaging).  How these values are represented in software is not so 
important (thought it might be useful for building common VO libraries).

However - this discussion on Quantity and the object model being built 
around it is helping to define the characteristics of astronomical 
values and the other values that go along with them.  So as far as that 
goes it is a Good Thing.

> Complete description of whatever astronomical data is not in the scope
> of Quantity but preferably in Observation global view.

I get the impression that Observation will describe Sky Catalogue-style 
data, but not much else, and we will need other data models.  I've read 
it just once so far though.

> 
> I am not an institutionnal representative,
> so my opinion has no political weigth.
> I am only a technical part waiting for common standards,
> to eventually use them, instead of using ad hoc, private,
> partial and imperfect definitions in my little corner.
> So my comments are only the "feelings" of an eventual
> simple/dummy user.

Which is why your comments are useful!  We need to make sure that the VO 
we produce can and will be adopted by others, and doesn't turn into some 
grand white elephant with standards that are too hard or insufficiently 
complete to be used by the wider astronomical community.

MC


-- 
Martin Hill
www.mchill.net
07901 55 24 66