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
Received on 2005-12-23Z18:16:18