[Dachs-support] Two questions on datalinking
Yannick Roehlly
yannick.roehlly at lam.fr
Thu Aug 26 09:17:19 CEST 2021
Hi all,
Le jeudi 26 août 2021, 09:02:08 CEST Markus Demleitner a écrit :
> > 2. The main download link of the data then. I think I have three choices
> > (basically what I want to bind the path to). The dlmeta, the dlget or a
> > direct link to the remote data set. I find it hard to understand how much
> > of a difference that makes in practice and whether or not there should be
> > a preference for using either. Will Aladin be able to handle dlmeta links
> > more or less transparently for instance?
>
> So, last time I checked the mainstream Aladin didn't handle datalink
> all that smoothly, but it's been a while. Still, I'd see two basic
> cases:
>
> smallish data (up to ~1e8 bytes these days): Just put in the
> direct link. Datalink-aware clients will still find datalinks
> because there's a descriptor block, and if you want, you can put in
> an extra datalink column as described at the end of
> http://docs.g-vo.org/DaCHS/ref.html#integrating-datalink-services so
> even browsers can see datalinks.
>
> (b) largeish data (more than ~1e8 bytes these days): You probably
> don't want to entice people to blindly download those, and so I'd
> point to dlmeta. It'll not be immediately pretty, but when people
> have to pull large amounts of data, it'll never be really pretty.
I may add another use case here to the use of the datalink: to have
homogeneous outputs; in particular for spectra.
If you are serving spectra, using the datalink allows Topcat to plot them even
if the spectra are stored as image FITS files. Also, you may have a
collection of inhomogeneous spectra files (some as table, other as images with
different formats) and using the datalink allows you to have every time the
same answer.
Yannick
--
Where it is a duty to worship the sun it is pretty sure to be a crime to
examine the laws of heat.
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