MyUCDs & Registry

[Tony Linde]

Wow! This topic seems to have mushroomed. A few points:

1. The IVOA will define interfaces to the Registry and the minimum standard
that any registry should conform to. It will be up to each registry how it
implements those standards and whether they offer extension services. 

So, to the first point, the standard may say that a registry must return the
columns defined in a dataset but one implementation might store that
information for every dataset and another might query a dataset when it
needs to answer such a query. On the second point, a registry might offer to
run queries and consolidate results on behalf of clients - that does not
mean that all registries have to offer such services.

2. There is likely to be very little information which is mandated across
all resources listed in a registry. Simple curation metadata (owner email,
phone number etc) is probably all that every resource will have in common. 

We can then imagine an inheritance hierarchy of metadata sets branching out
from that. One branch will be resources offering to provide data from a
query (such metadata will include data type, coverage etc); one branch from
that might be for images and another for catalog data etc. Another top-level
branch might be for services; from that a branch for visualisation tools
etc. Each branch will have metadata associated with it; and lower levels
will have more specific data associated with them.

This is similar to the OAI 'metadata format'. A resource, when added to the
registry, will state that it is of type 'X' and that it will agree to
provide metadata in formats A, B, C (ie it will provide metadata under those
branches). Having signed up to provide such metadata, a registry query
against that resource can then identify one, some or all of the metadata
formats required as an answer to the query.

3. For data-oriented resources, the metadata should include UCDs and column
names. The UCD will go some way towards identifying the type of data in a
column. It will be possible to query the registry for all 'data-oriented
resources' (eg all resources which have agreed to satisfy the 'dataset'
metadata format) for which there is one or more columns described by
POS_EQ_RA or equivalent.


In summary, the RSM must expand to cover all the above if we intend it to be
the final standard for describing the metadata in the Registry.

Cheers,
Tony. 
__
Tony Linde                       Phone:  +44 (0)116 223 1292
AstroGrid Project Manager        Fax:    +44 (0)116 252 3311
Dept of Physics & Astronomy      Mobile: +44 (0)7753 603356
University of Leicester          Email:  ael at star.le.ac.uk
Leicester, UK   LE1 7RH          Web:    http://www.astrogrid.org