MyUCDs & Registry

[Clive Page]

On Tue, 20 May 2003, Tony Linde wrote:

> The column names have to be inserted into the query before it is sent out.
> It may start out as generic but, in order to be resolved at the dataset end,
> it must have some specificity added.

Tony et al

This was discussed at some length in the VOQL group (and maybe also in the
registry group?).

We are assuming that we have some generic queries, such as a cone search
with added constraints (e.g. V_magnitude > 20) which can be sent out
meaningfully to multiple sites.  Clearly the only way to specify these is
to use UCDs, since column names will vary.  Somewhere the UCD has to be
translated into a specific column name.  This _could_ be done by the
Registry, if it has the requisite information, but it may not, because not
everyone is yet convinced that the fine-grained Registry is the way to go,
so not all of them may ingest the necessary data.  It can _always_ be
translated by the end data centre, since it knows the names of its own
columns.  If information on the UCDs of each column is not present at the
end data centre, then it will almost certainly not be present in the
Registry, since where else can it come from?  So we concluded that the
most reliable way to do the translation is at the data centre.  This
simplifies the Registry and workflow, without significantly complicating
the data centre interface (which has to be handle UCDs and columns
anyhow).

> PS: Sorry about the cross-post. This seems to be more of a VOQL question
> now, so shall we continue the discussion on that list ??

That's what I've done.  Sorry if Registry folks have to read the VOQL
archive to see this posting.


-- 
Clive Page,
Dept of Physics & Astronomy,
University of Leicester,    Tel +44 116 252 3551
Leicester, LE1 7RH,  U.K.   Fax +44 116 252 3311