Collaboration on Source Catalogue DM, ADQL and SkyNodes

[Roy Williams]

Pedro

As Maria points out, the work done so far on source catalogs assumes a 
RDBMS table model. There is the Skynode protocol that allows an 
arbitrary table to be exposed through web services that allow discovery 
of the list of tables and table metadata, and to send queries (ADQL, 
based on SQL) to the database. The model is extended in the case of 
tables that have positional information, where crossmatch and regions 
are introduced.

Your Catalog model is thus a further extension of Skynode.  It seems 
that you are adding
(1) Curation, content, and coverage information for the catalog, and
(2) Specific semantic meanings for the columns of the table

Is this a correct interpretation?

(a) In the case of (1), can you tell me if you have used the Resource 
Metadata model/schema that the Registry group has built? If some large 
catalog is published to the Registry as a Data Collection, can I copy 
the curation-content-coverage information verbatim and use it in your 
catalog model. (If not, why not?)

(b) Your section 3.4 (page 12) has specific definitions of words that 
describe sources. For example "redshift" and "radialVelocity".  Can I 
assume that these can be used as the utype attribute of VOTable? The 
representation of a table might look like this:
	<FIELD name=z utype=dmc:redshift>
Is that correct?

(c) Your page 5 shows a query "in pseudo-code". How close is this 
pseudo code to real ADQL? It looks like you are using your utypes in 
place of column names. In the example above, how do I ask for high 
redshift sources, do I say "select * where z>4" or do I say "select * 
where dmc:redshift>4"?

(d) To what extent do your source attributes match up with the UCD 
list? In other words, a great deal of effort has already been used in 
labeling catalog column names with UCDs (Vizier, SDSS, HEASARC, etc 
etc). I hope that there can be a direct, semantically-equivalent 
translation to your source attributes, otherwise I do not understand 
how you expect the Catalog model to gain implementation.

(e) For the source identifier, is your format the same as what the ADQL 
group has carefully defined?

Thank you and Feliz Navidad
Roy

California Institute of Technology
626 395 3670
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