linking capabilities with tablesets

[gilles landais]

Dear Registry followers,

We didn't find any clean method to link capabilities with tablesets 
described in a VORegistry record.

For instance, the VizieR Gaia catalogue (ivo://cds.vizier/i/355) 
contains 9 conesearch capabilities to query tables which are described 
in the same VO registry record in "tableset".

This lack of information impacts the registry usage. We see it as much 
in pyvo  (ex: https://github.com/astropy/pyvo/pull/505 ).

Technically, the tablesets are declared using VODataService, the 
capabilities using VOResources.
We propose to add a mechanism to link the capability with tableset(s) 
described int the same registry record.

For instance, we could imagine a VOResource extension "serve" containing 
a list of links based on the VODataService "tableset.table.name"

(in OAI XML)

<capability xsi:type="cs:ConeSearch" 
standardID="ivo://ivoa.net/std/ConeSearch">
     <serves>
         <reftable name='@table1' />
         <reftable name='@table2' />
     </serves>
</capability>

...

<tableset>
     <schema>
        <table>
            <name>table1</name>
....



Regards,

Gilles Landais (CDS), Manon Marchand (CDS)