SODA, half-client and remaining gripe collection

[Markus Demleitner]

Hi all,

On Mon, Apr 11, 2016 at 11:56:16AM +0100, Mark Taylor wrote:
> On Tue, 29 Mar 2016, Markus Demleitner wrote:
> 
> > (6) @value="" universally valid
> > 
> > VOTable 1.3 says "If the TD element is empty (<TD/> or <TD></TD>) the
> > cell is considered to contain no data, i.e. to be null."  Since we're
> > saying "parse PARAM/@value like you parse TABLEDATA cells" (I really
> > think VOTable itself should say this in sect. 4.1, last bullet point), I
> > *think* we're fine saying "Generate your UI from all the PARAMs that
> > have value="" (which, in effect, we're doing right now and we'd
> > certainly be doing if we adopt (5).  I'd much prefer if that were made
> > explicit somewhere.  Bug me for a doc patch if everyone interested agrees.
> 
> It is probably true that VOTable ought to specify this.
> However, it's not too surprising that it doesn't.

Uh -- I think the question of PARAM/@value literals is independent of
this particular use, and I'd still suggest VOTable should say "These
values are encoded as if it were TABLEDATA cells." and then perhaps
something as to whether or not VALUES/@null is to be evaluated.

Nothing I can make out in the current VOTable spec says that much,
and I strongly suspect that if we looked at current implementations,
not many actually work like this (and consequently probably fail as
soon as we have array-typed PARAMs).

> This use of PARAM to document service parameters comes pretty close
> to abuse of the PARAM element; the fact that 'PARAM' sounds a bit like

True, but that kind of a..., well, ad-hoc use goes back to SIA, where
it's been present at least since 2004:

http://www.ivoa.net/documents/WD/SIA/sia-20040524.html#mdquery

So, as much as I would like to have better, more expressive, and less
a... well, ad-hoc parameter descriptions, I'd say this one has at least
stood the test of time.

Cheers,

          Markus