Re: [Plastic-devs] spectrum messaging

[Mark T. <m.b...@br...>]

On Tue, 15 Aug 2006, John Taylor wrote:

> Mark Taylor wrote:
> > Chaps,
> >
> > []
> >
> > An alternative (and one that I'd like to see) would be
> > ivo://votech.org/fits/spectrum/loadFromURL, which would make sense
> > sitting next to  fits/image/loadFromURL.
> >
> > Mark
> 
> I'd go with that, _unless_ there could ever be a need to load a 
> fits-format spectrum into a general fits image viewer (which wouldn't 
> know about fits/spectrum/...).  If there is such a need, then we could 
> go for ivo://votech.org/fits/image/loadFromURL#loadSpectrum (assuming 
> this "annotating with fragments" idea is accepted.)
> 
> John

Thinking slightly more carefully about it, I think what we need is
separate named messages for 1D, 2D and >=3D FITS arrays.
The 'image' one (though it doesn't currently say this explicitly in 
the message description) is probably understood already to mean 2D.
I *don't* think that this distinction would be best handled using 
fragments, since the difference refers to a well-defined 
characterisation of the type of data, not just how the client is
to understand it.

Naming is a bit of a problem; "cube" is often understood to mean 
high- rather than strictly 3-dimensional, so that's probably OK, 
but "spectrum" is not good for 1D since not all 1D arrays are
spectra (e.g. could be time series).

So maybe 

   1D:  ivo://votech.org/fits/line/loadFromURL
   2D:  ivo://votech.org/fits/image/loadFromURL
  3+D:  ivo://votech.org/fits/cube/loadFromURL

Fragments probably are the best way to distinguish between [uses for]
different physical meanings for some of these things, e.g.

  ivo://votech.org/fits/line/loadFromURL#spectrum
  ivo://votech.org/fits/line/loadFromURL#timeseries

though an application which can just plot graphs won't care
about the difference so would use the un-fragmented message.

Mark

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