x-samp.query.by-meta

[Mark Taylor]

Thomas (and Luigi),

Certainly the most obvious usage pattern would be for the hub to 
implement this MType.  If it makes it into the standard it could even
be a SHOULD or MUST for the hub to do so.  However, even if that
happens, clients will have to be prepared for the hub not to implement it,
for instance they might find themselves using an older hub version.

If you're deploying multiple clients A1, A2, A3 that might like 
to use that MType, it could be convenient to deploy another client B
which implements it for convenience of the others if the hub is
found not to implement it, especially if you can guarantee that B will
always be present when A1, A2 and A3 are.  A client is capable 
of implementing it efficiently if it keeps track of metadata using 
the various samp.hub.event messages.

But, there's no general rule that clients cannot implement a samp.hub.*
MType, so that doesn't absolutely preclude calling this one 
samp.hub.query.by-meta or similar.  If most people prefer a samp.hub.*
name I've got no objection to changing it.

Mark

On Mon, 21 Nov 2011, Thomas Boch wrote:

> Hi Mark,
> 
> I think the idea is nice, but I do not see the rationale in not making it a
> samp.hub.* MType.
> Do you have use cases where regular applications would like to implement this
> ?
> 
> Cheers,
> 
> Thomas
> 
> Mark Taylor wrote:
> > Hi all,
> > 
> > following a suggestion from Luigi, I've added a draft for a new experimental
> > MType, x-samp.query.by-meta, to the
> > http://www.ivoa.net/cgi-bin/twiki/bin/view/IVOA/SampMTypes
> > wiki page.  The main point of this is to make it easy for SAMP
> > clients to find the ID of a client with a given name, e.g.
> > "is Aladin registered, and if so what's its client ID?",
> > though it can be used in more general ways too.
> > This would typically be implemented by the Hub, though since
> > normal clients could implement it, my feeling is that it an
> > (x-)samp.hub.* name would not be appropriate.
> > 
> > The description on that wiki page is just my first draft for discussion;
> > if anybody wants to change/improve/rename it, or thinks it's a bad
> > idea, please edit it and/or discuss it on this list.
> > In particular: Luigi, does this do what you had in mind?
> > 
> > Mark
> > 
> > --
> > Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
> > m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/
> >   
> 
> 
> -- 
> Thomas Boch
> Ingénieur de Recherche
> 
>  CDS/Observatoire Astronomique   Phone  : 33 (0)3 68 85 24 42
>  11, rue de l'Universite         Fax    : 33 (0)3 68 85 24 17
>  F-67000 Strasbourg              Email  : thomas.boch at astro.unistra.fr
>  France                          http://cdsweb.u-strasbg.fr/~boch 
> 

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/