SIA 2.0 POS parameters

[Walter Landry]

Markus Demleitner <msdemlei at ari.uni-heidelberg.de> wrote:
> On Tue, Jul 08, 2014 at 11:04:29AM -0700, Walter Landry wrote:
>> I would be fine with that.  I would expect that if a user has multiple
>> coordinate systems in a query, they are not too averse to doing
>> coordinate transforms.  It is the people who only 'think' in Galactic
>> who would just flip that switch.  For them, doing transforms could be
>> quite onerous.
> 
> ... as it would for people thinking in supergalactic or ecliptic or
> whatever else fancies your mind.  This is why we design *protocols*:
> These people need a (trivial or complex) client, and it's our
> responsibility to make sure they're there, in astropy, in Aladin or
> TOPCAT, on the command line, within ds9.  From there, they can work
> in whatever coordinate system the prefer, and do all the necessary
> coordinate transforms they know to be required for their particular
> data.
> 
> A protocol, on the other hand, *is* no user interface.  UI aspects
> enter ("Can a UI discover all it needs to in order to provide good
> user experience?"), but user interface design doesn't.  If you design
> the protocol based on the question "Can we make the protocol such
> that sed and curl are strictly enough for operation?", you'll get
> protocols that suck for both sed/curl *and* actual clients.

To some degree, I agree.  For example, we answer registry queries with
xml.  Xml is not sed/curl friendly, but plain ascii would be a
disaster.  On the other hand, for the final data products, we do
provide some user convenience.  Users do not have to parse votables,
but can get ascii or fits or anything else the service can provide.
For that, users do use sed/curl and would like to continue to do so
without undue hardship.

Cheers,
Walter Landry