Re: [Plastic-devs] spectrum load message

[Thomas B. <bo...@ne...>]

Hi Mark,


> So I've revised my proposal, as follows:
> 
>    boolean ivo://votech.org/spectrum/loadFromURL( String url, String id,
>                                                   Map meta )
> 
>       Loads a spectrum or SED. id is an identifier as for the VOTable
>       load message - use the URL if there's no reason to do otherwise.
>       The meta argument is a map/struct containing additional
>       information about the type of data found at url which encodes
>       the spectrum. The entries of this map take the form of
>       utype->value pairs, where the keys (utypes) are as defined
>       in the SSAP specification, e.g. "Access.Format" for MIME
>       type. As many or few of these entries as are known may be
>       filled in.
> 
> (...)
> 
> Sending this message should be easy to implement by an SSAP client
> (e.g. AstroScope) which wants to pass the spectrum selection on to
> viewers, since it can just scoop up the fields from the relevant
> row of the SSAP response VOTable and pass them on in a Map without
> having to know or care what they mean.

I agree, this sounds sensible and pragmatic to me.

> This message can of course be used to pass spectra around which
> do not result from actual SSAP queries, since you can add metadata
> map entries by hand as if they'd come from SSAP (or just leave the
> metadata map empty).

Indeed, it is important to leave the door open for spectra *not* coming
from an SSAP service (eg. local files, MySpace account). For those
spectra, we certainly won't have all the metadata Isa has described, and
it will be up to the spectrum tool to try to obtain needed metadata from
the spectrum itself.
Thus, I think we should precise that tools sending a
ivo://votech.org/spectrum/loadFromURL message should give as many
metadata information as they can, but that no parameter is really
'compulsory'.

Cheers,

Thomas