SIAPv2 and datacubes and polarization

[Guy Rixon]

Anita,

my vision of SIAP 2 retains the initial search returning the metadata  
of images/cubes in a VOTable.
It's the second stage - using the accrefs - that needs to change to  
allow image staging.

Suppose that you query the service and it gives you 20-odd potential  
images of which you select
5. In SIAP 1, with synchronous access to the images, you get each of  
the 5 by streaming data from
an accref; each acquisition of an image is a separate connection to a  
service. In SIAP 2, when images
have to be computed, or raised from slow storage, I suggest that we  
have accrefs that lead to UWS
jobs rather than directly to data. That is, the client posts to the  
given accref to start the staging process
for one image. The client later streams the result from a different  
URL discovered from the UWS
metadata rather than stated in the VOTable.

The above scheme is one UWS job per selected, staged image. An  
alternative is to make all five
selected images in one UWS job and to have UWS return a second VOTable  
saying where to find
the results. I dislike this alternative because it's more complicated;  
but it is feasible if it's useful.

Cheers,
Guy


On 25 Mar 2009, at 13:36, Anita M. S. Richards wrote:

>
>
>
> On Wed, 25 Mar 2009, Guy Rixon wrote:
>
>> Anita,
>>
>> do you find it necessary that the accrefs be returned in a VOTable?
>> In a "natural" (=simplest) application of UWS, the accrefs would be
>> obtained separately. Either one job per cube, with one accref per  
>> job,
>> or one job making five cubes returning five accrefs. It's possible to
>> make the UWS job return a VOTable of accrefs, but it's not worth the
>> complication unless there's a specific gain.
>>
>
> Thanks Guy,
>
> The SIAP (old) standard VOTable (containing some WCS and other info  
> and accrefs) has the advantage of being recognised by applications  
> such as Aladin, so that it can be sent thereto, used to provide  
> basic metadata e.g. resolution, position, and the field of view can  
> be visualised wrt other images and then you can use the accref to  
> obtain the images you want.
>
> If, instead, you were to return the accref as you suggest, would it  
> be naked i.e. only accessible by cut and paste? Or in a text file?  
> Or how do you envisage this? Maybe there is a better way I am not  
> seeing...
>
> thanks
>
> Anita
>
>
>
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  
> - - -
>
> Dr. A.M.S. Richards, UK ARC Node/AstroGrid,
> Jodrell Bank Centre for Astrophysics, Alan Turing Building,  
> University of Manchester, M13 9PL
> +44 (0)161 275 4124
> and
> MERLIN/VLBI National Facility, Jodrell Bank Observatory, Cheshire  
> SK11 9DL, U.K. +44 (0)1477 571321 (tel) 571618 (fax)
>
> "Socialism or barbarism?" Rosa Luxemburg (1915)

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 3006 bytes
Desc: not available
URL: <http://www.ivoa.net/pipermail/dal/attachments/20090325/78e751c4/attachment-0003.bin>