Quantity "tables"

[Tony Linde]

Sounds good to me, Doug. Will it be finished by next week so we can ratify
it at the exec? :)

T.

> -----Original Message-----
> From: Doug Tody [mailto:dtody at nrao.edu] 
> Sent: 22 January 2004 20:50
> To: Tony Linde
> Cc: dm at ivoa.net
> Subject: RE: Quantity "tables"
> 
> 
> > Your example is fascinating but I wonder if someone else 
> approaching 
> > the same set of data would create the same hierarchical 
> structure: ie, 
> > how easy is it going to be to get all astronomers to agree 
> on the one 
> > hierarchical structure for the representation of astronomical data. 
> > Maybe we need to define all the primitives - quantity, ucd, unit, 
> > instrument, etc - and some of the most common and agreed simple 
> > structures like position and then come up with the ability for 
> > astronomers, data centre managers, developers to combine these into 
> > appropriate hierarchies for representing metadata. Using the same 
> > primitives will at least allow interpretation of results 
> even if they 
> > exist in unfamiliar structures.
> 
> Tony - This is exactly what we mean when we talk about 
> component data models which can be aggregated and associated 
> to model complex datasets.
> 
> We will never develop one data model for all astronomical 
> data (one model to rule them all?).  A realistic approach is 
> to model obviously useful things which are small enough that 
> we can understand and agree upon them
> (components) and then stick these together to model actual 
> datasets. A "spectrum" or "image" model would be assembled 
> from these components. A conformant dataset would supply the 
> minimum required elements of the dataset, but a given data 
> provider could add other elements as well. This would give 
> us, for each dataset, a standard core built from standard 
> components, plus the ability for data providers to extend the 
> core model with whatever information is required to describe 
> the peculiarities of their data.  This would allow the 
> structure we define in VO to evolve to work with the real 
> data that data providers will publish to the VO.
> 
> 	- Doug
>