Comments on SSAP V0.95, UCDs

[Doug Tody]

Hi Gretchen -

This is NOT a complex hierarchical interface.  The idea with the query
response is that it is a flat table; each field has a UTYPE and other
tags (name, ucd, etc.).  UTYPE is just a simple fixed string, so to
access a field one can just do something like  getField(<utype>).
Hence you still have a simple direct reference, although there may
also be some logical structure behind what is presented.

Another way to look at it is that we have component data models with
some limited internal structure, however using the UTYPE mechanism
we can map everything to a flat name space, be it a VOTable, a hash
table, a parameter file, or whatever.  This makes things referentially
very simple but still provides some logical structure with reusable
components.

 	- Doug


On Tue, 27 Jun 2006, Gretchen Greene wrote:

> Doug,
>
> Let me get this clear,  to specify ra, dec you are seriously considering
> something to level 4 hierarchy?
>
> -Gretchen
>
> -----Original Message-----
> From: owner-dal at eso.org [mailto:owner-dal at eso.org] On Behalf Of Doug
> Tody
> Sent: Tuesday, June 27, 2006 2:01 PM
> To: Randall Thompson
> Cc: dal at ivoa.net; Inga Kamp; Myron Smith
> Subject: Re: Comments on SSAP V0.95, UCDs
>
>
> On Tue, 27 Jun 2006, Randall Thompson wrote:
>
>>   What I was hoping for was something equivalent to the
>> UCDs POS_EQ_RA_MAIN and POS_EQ_DEC_MAIN defining
>> the "primary" coordinates for a given observation, that would be
>> included in the query results returned for any protocol. Will there be
>
>> a single equivalent UTYPE I can use instead?
>>   Randy
>
> Yes - Assuming we still try to use characterization for this, probably
> it will be provided by something like
> SpatialAxis.Coverage.Location.whatever.
> If that proves too complex for something this fundamental (we still
> don't know how to specify a coordinate at this level), we will define a
> special field for this purpose with a fixed coordinate system reference
> frame, as in the past.  Whatever is decided, it will be a well defined
> interface element with a fixed UTYPE so that you can just look up the
> position by its UTYPE string.
>
> 	- Doug
>
>
>