Re: MyUCDs

On Mon, 19 May 2003, Marco C. Leoni wrote:
> Hi Patricio,
> one question about the point below:
>
> > Let me include here another element before the submission of a
> > query to the resource handling catalogues: The registry.
> >
> > Any registry will contain metadata about the services listed, ie,
> > the catalogues.
> > The registry would know (among other things),
> > - catalogueName (possibly catalogueUniqueID)
> > - catalogueTitle
> > - catalogueKeywords
> > - catalogueAuthor
> > - number of columns
> > - number of records
> > - column names, UCDs, units
> > - name ID,MAIN ---
> > - RA POS_EQ_RA,MAIN h:m:s
> > - Dec POS_EQ_DEC,MAIN d:m:s
> > ....
> > - Vmag PHOT_JHN_V mag
> > - Bmag PHOT_JHN_B mag
> > - z REDSHIFT ---
> >
>
> are you sure the Registry will include all these information?
> Perhaps "column names" and "units" will be resolved by the service
> provider, and not by the registry itself.
>
> Cheers,
> Marco

Hi Marco,

well, I would have thought so. It's done already by vizier meta-information tables (which could be considered a local registry) and surely by other services. It's a good point though, how much is a registry supposed to know? In the scheme that Keith Noddle presented in Cambridge, I would expect at least the local register (read service provider's) should know about about this. Whether the higher level registers decide to collect this information is to be seen, but if you ask *me*, I would say yes, they should keep this information. We are not talking about a huge data volume here; the advantages are large though, as you don't have to go everywhere with your query.

I just had to deal with getting a mortgage and run from bank to bank filling up applications not knowing if I satisfied all the conditions they asked; then a consultant phoned us and we dealt with him, he found out who would lend us the money and it worked fine. The analogy seems quite appropriate for our situation in VO. An astronomer wants to formulate a general query, he or she has no idea where this could be done, so s/he asks a service to lauch the query urbe et orbi... Surely the data will come back to the astronomer, but if we apply a filtering system which can select the services which may give a positive answer (and weed off the ones with a negative), then the number of transactions diminishes and the response time is shorter.

An intermediate solution would be to send the query to broker-services urbe et orbi, and let those services do the filtering and send the query to places which may give a positive answer.

IMHO not using this meta-information would be a real waste.

Cheers,

Patricio

---
Patricio F. Ortiz			pfo-at-star.le.ac.uk
AstroGrid project
Department of Physics and Astronomy
University of Leicester			Tel: +44 (0)116 252 2015
LE1 7RH, UK