SODA, half-client

[James.Dempsey at csiro.au]

Hi Markus,

I'll just focus on the client in this reply. 

I've had a play with the SODA client and it works very nicely.  I particularly like the rubber band selection in Aladin Lite and the on the fly conversion of different units for BAND. We are just starting to spec a web UI for multi-d cutouts, so this is a timely example to share with my colleagues - thanks.

While no doubt outside the prototype UI, the downloaded file has a static name dlget. It would be useful if this had a fits extension and perhaps related back to the original image.

Cheers,
James.

> -----Original Message-----
> From: dal-bounces at ivoa.net [mailto:dal-bounces at ivoa.net] On Behalf Of
> Markus Demleitner
> Sent: Wednesday, 30 March 2016 1:21 AM
> To: dal at ivoa.net
> Subject: SODA, half-client and remaining gripe collection
> 
> Dear Colleagues,
> 
> Sorry that this is again a rather long mail, but it should be the last of these
> monsters on SODA for a while.  Also, it's split into two sections, the first of
> which I'd ask everyone with some interest in SODA to at least have a glance at.
> The rest is for the nerds.
> 
> 
> I. SODA Prototype
> -----------------
> 
> So, building on the XSLT hack for datalink I reported on in Syndey (see below for
> details) I've now done a makeshift SODA client so you can try out how these
> things could work (and see where we should work on the client side).
> 
> To follow these instructions, start TOPCAT and Aladin.
> 
> (1) Discovery
> 
> We're using obscore; so, in TOPCAT open the VO/TAP dialog, double click the
> "GAVO DC TAP" entry you're seeing.
> 
> Use
> 
>   select * from ivoa.obscore
>   where
>   dataproduct_type='cube'
>   and obs_collection='CALIFA'
> 
> as your query.  Or, really, anything that'll return one of these cubes (also see
> below, at (4) Other data).
> 
> (2) SODA
> 
> There's not yet a cube-enabled SODA client, so I'm using a bit of XSLT and
> javascript that lets you use SODA results in the browser.  To use it, in TOPCAT's
> main window click "Activation action" and check "View URL as a Web Page".
> Select "access_url" as "Web Page Location column"
> and "system browser" (or anything but "basic browser") as the Browser type.
> "Ok" the dialog.
> 
> Now open a plot or table display for your obscore result.  When you click on a
> row or point, a web browser page opens with a SODA dialog.
> If you have javascript disabled, you can use a conventional form interface,
> where the thing at least tells you what you can enter.  This particular service
> supports BAND and POS from the current SODA draft parameters, and in
> addition RA and DEC (which I claim we can't really do without, see the nerd
> section).
> 
> There's also some additional parameters in there that might be up for later
> standardisation -- don't worry about them now.  Up to now, that's all datalink.
> 
> If you enable Javascript, you'll get some SODA magic:
> 
> (a) there's a spatial cutout overlaid on a sky preview courtesy of the Aladin
> image server.  Use a click-and-drag rubberband to determine your spatial
> cutout.
> 
> (b) You'll get a custom BAND widget that lets you do the cutouts in your chosen
> units.  For instance, to get the vicinity of H alpha, switch to Ångström and enter
> 6560 and 6564 there (or something else if you got a cube that doesn't have
> Halpha -- you'll see that readily from the limits).  Yes, the formatting of the
> limits in that widget is suboptimal at this point.  Visual improvements
> forthcoming.
> 
> Notice how changing these "custom" widgets updates the SODA parameters (in
> the case of the spatial units, I could change POS, but since I have RA and DEC
> anyway, I use this).
> 
> (3) Retrieval
> 
> Hit "broadcast dataset via SAMP" and inspect your cutout in Aladin (or DS9, for
> that matter).  Or hit "Retrieve data" to download the cutout.
> 
> 
> That's about it; no, I'm not claiming the XSLT-thing is more than a proof-of-
> concept client.  But still, I think you can get an idea how the pieces can fit
> together.
> 
> 
> (4) Other data
> 
> This happens to be useful for other data, too.  For instance, I have this
> collection of plate scans that are a Gigabyte a pop.  With SIAP, I only handed
> out cutouts, but that's not an option with obscore, so I've always been a bit
> worried.  Now, I'm handing out datalinks for those.
> So see how things work out for these images (in effect, degenerate cubes), try a
> discovery query like
> 
>   select * from ivoa.obscore
>   where
>   t_min<gavo_to_mjd('1925-01-01')
>   and target_name='M42'
>   order by t_min desc
> 
> If you don't want to configure the activation action, you can simply cut the
> access URL in TOPCAT with a quadruple click and paste it somewhere else.