Error column in VOResource

[Tony Linde]

The two-step is just an internal NVO requirement - registry implementations
like AstroGrid and CDS will contain rich metadata. What impact the NVO
approach has on querying we'll need to discuss at the session on RI.

T.

> -----Original Message-----
> From: owner-registry at eso.org [mailto:owner-registry at eso.org] 
> On Behalf Of Martin Hill
> Sent: 18 May 2004 16:17
> To: Ray Plante
> Cc: registry at ivoa.net
> Subject: Re: Error column in VOResource
> 
> Hmmm.  This does seem an unnecessary two-step operation.  I 
> thought column/table names would be in the Registry anyway 
> (so discovery tools can look for UCDs for example, etc).  So 
> it'll need to go into VOResource, which is (I have been 
> assuming...) always available from the datacenter using 
> SkyNode's getVOResource() method.  So why duplicate? 
> Is it just for VOTable tools?  If so, which ones?  If new 
> ones are going to have to be written, then we might as well 
> write ones for the richer VOResource, or...?
> 
> A helper method that extracts column names, UCDs and Units 
> would be convenient I think, but is that not just returning 
> the correct element of VODataService?
> 
> Ray Plante wrote:
> 
> > On Tue, 18 May 2004, Martin Hill wrote:
> > 
> >>If you mean that a service returns a VOTable, and so we can 
> ask for a 
> >>VOTable header, that rather implies that you know already which 
> >>columns to ask for, as the resultset will not (I believe?) give all 
> >>the columns every time.
> > 
> > 
> > The purpose is to discover all the possible columns.  As an 
> example, 
> > see the SIA spec, section 7.1 
> > (http://www.aoc.nrao.edu/~dtody/sim.html#registration).  A metadata 
> > query returns a VOTable with no rows but all the columns 
> that can be returned.
> > 
> > SkyNode has an specific operation for retreiving column names and 
> > their UCDs.  This is not has rich a response (however, this 
> spec is in 
> > development).
> > 
> > cheers,
> > Ray
> > 
> > 
> > 
> 
> 
> --
> Martin Hill
> www.mchill.net
> 07901 55 24 66
>