Draft note on STC in the Registry

[Mark Taylor]

On Fri, 26 Jan 2018, Markus Demleitner wrote:

> > In VOTables, an array-valued integer-typed cell can efficiently
> > (for BINARY/2 serialization anyway) store MOCs in this form,
> > and it should(?) be more straightforward for clients to ingest.
> 
> I'm not awfully convinced as regards the compact representation -- the
> ranges in ASCII are fairly nifty, and the All-Sky 0/0-11, at least,
> is hard to beat.  And either way, I suspect it doesn't buy much
> (like: factor of two) in the typical cases, in particular if you gzip
> the VOTables.  However, we can just try it of MOCs we find in the
> Registry, and I'd do that if there's sufficient interest.
> 
> I'd consider the question of straightforwardness in handling much
> more insteresting.  For me, where the database (at least for now)
> accepts and supplies ASCII MOCs, ASCII is a lot simpler, more
> human-readable, and reasonably nice in VOResource, so they appear to
> me as more attractive in VOTable as.  But obviously NUNIQ wouldn't
> require higher magic, either.
> 
> When handling these things from C, I can absolutely believe that
> NUNIQ arrays are highly preferable unless you have a nifty and
> well-written library.
> 
> So, I'm not sure and could be convinced either way.  Whatever we
> do, I'd strongly suggest the serialisation should be the (within
> reason) the same between VOTable (tabledata) and VOResource.
> 
> Since I'd say this needs further discussion and possibly research, in
> particular over on Apps, I've put it in as another question to
> consider (Volute rev.  4717).

OK well I don't have a strong opinion.  If the general feeling
is that the ASCII representation is approximately as good or better
than the numeric one, I won't push for a change.

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/