TAP issues (fwd)

Francois Ochsenbein francois at vizir.u-strasbg.fr
Thu May 3 10:10:05 PDT 2007


About the metadata access and getCapabilities:

-- the specification of which version of ADQL/VOQL (if any) suggested
   by Maria looks to me a useful component of the getCapabilities
   (it should obviously be stored also in the register)

-- for the metada discovery, I would like to insist on the semantics
   part (meaning of the parameters), which is in my opinion at least
   as important to issue meaningful queries as the description of the
   relational schema. Some components are probably not important: is
   it for instance important to specify how indexes are built ? or 
   to specify that some "table" is in reality a view ? 
   Getting the metadata have been proposed via essentially two ways:
   either via methods like getTable() getColumn() getRelations()...,
   or via a set of SCHEMA tables. In both cases, there is a need
   for an accurate description of the components making up the 
   table(s), column(s) etc. The "SCHEMA" tables implementation could
   hardly be some standard component of a DBMS, our needs for units, 
   UCDs, utypes etc being quite specific -- and being a fundamental
   piece of the metadata retrieval, an evolution could be quite

   It could be noticed that the "SCHEMA" tables way enables more
   sophisticated queries of metadata than the "methods" -- which on
   the other hand are easier to handle in the basic approach

All this was already discussed last year -- maybe it would be time
to write down an actual proposal for this metadata components or schema ?

Francois Ochsenbein       ------       Observatoire Astronomique de Strasbourg
   11, rue de l'Universite F-67000 STRASBOURG       Phone: +33-(0)390 24 24 29
Email: francois at astro.u-strasbg.fr   (France)         Fax: +33-(0)390 24 24 32

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