prototype TAP-1.1 service

[Markus Demleitner]

Hi Pat,

[crossposting to Registry]

On Wed, May 27, 2015 at 03:05:11PM -0700, Patrick Dowler wrote:
> I was unable to describe the TAP-1.1 capabilities with TAPRegExt because it
> restricts the standardID to a single value. That makes no sense to me since
> one should be able to use that description to describe any service where
> that metadata is applicable, not just TAP-1.0; it certainly isn't supportive
> of new versions. But the content is hiding there in a comment and shows that

You are probably right -- for those not familiar, the practice in
all the schema files describing our standard capabilities has been to
first derive a restriction of vr:Capability that fixes the standardId
to a single value, and then extend that type to add the special
children for the capability in question; for instance, in
http://www.ivoa.net/xml/SIA/v1.0, there's the abstract type
sia:SIACapRestriction, which is just vr:Capability with standardId
fixed to ivo://ivoa.net/std/SIA, and then there's
sia:SimpleImageAccess inheriting sia:SIACapRestriction, adding
information on limits of the image size and a test query.

I agree with Pat we shouldn't have had the restrictions fixing the
standardID.  The type sia:SimpleImageAccess can certainly be useful
for, say, SIAv2 (frankly, I don't see much need to evolve the
Registry extension if I look at the current draft); also the way we
do resource discovery, clients would discover SIA services even if
they didn't use the registry extension just by inspecting their
standardID -- so, really, there should be no coupling between
capability/@standardID and capbability/@xsi:type.

For TAPRegExt, which I believe is up for revision fairly soon anyway,
I've put that much on
http://wiki.ivoa.net/twiki/bin/view/IVOA/TAPRegExtNext -- you're
welcome to argue against that proposal either here (I propose to move
that discussion to the Registry list) or on the wiki.

Cheers,

      Markus