Use Cases for new Registry search interface

[Markus Demleitner]

Dear RWG,

On Mon, Jun 06, 2011 at 03:51:17PM +0200, Pierre Le Sidaner wrote:
> Le 06/06/2011 12:28, Markus Demleitner a écrit :
> >I'd really like to see a TAP/ADQL interface to searchable registries,
> >but we shouldn't forget that there is OAI-PMH and VOSI.  We may want
> I don't realy see the point, why tap ADQL to the registry ?
As Ray already pointed out, mainly to reuse a technology we've
already developed and that is up to the task.

> We should realy think of a search method in the registry based on
> very limited SQL (LIKE, WHERE, AND , OR) inside a search and keyword
> search.
-- but that would mean defining *another* language *someone* will
have to implement; on the other hand, people running searchable
registries probably have a TAP service somewhere anyway.

> maintaining XML schema will allow xml databases or mixed one
> (Postgresql including xpath).
That's another point -- I could very well see that we might not want
a (purely) relational registry representation at all but rather some
XML-based technology.  Paul has given some reasons to do so. 

My take is that if Ray's "three-table-or-so" simplified registry
model proves unfeasable, I'd definitely advocate looking into
X<whatever> again.  Even then, I'd suggest maintaining TAP as
"transport protocol" and just plugging in a different language than
ADQL.  Defining some ad-hoc transport protocol might seem attractive
at first, but in the end we'll end up solving quite a few problems
that TAP already addresses (e.g., response format selection,
paging[1], etc).

But *if* we're going relational, let's use what we've already defined
for accessing relational data (i.e., TAP with its default language
ADQL), both for keeping our implementation effort low and for making
the most of our users' efforts to learn our query language.

Cheers,

       Markus

[1] ok, TAP doesn't do paging, but since you can access async results
by HTTP and good servers can do partial transfers, you can, if you
insist, get about the same effect.