TAP, skynode, or boutique?

[Douglas Tody]

Hi All -

As Guy points out, we plan for TAP to include support for
multi-position queries, with no inherent limits (unlike SkyNode)
on either the number of positions or the size of the tables/query
results involved.

Using POS/SIZE will provide a basic spatial cross-match capability.
More sophisticated cross matching applications could do such a simple
spatial cross match as the first pass, then possibly refine the cross
match using additional non-spatial object attributes.  But the basic
capability will be simple and fully scalable.

 	- Doug


On Fri, 5 Sep 2008, Guy Rixon wrote:

> Roy,
>
> quoting from the TAP/PARAM draft that was current before the Trieste meeting:
>
> 3.3.6 Multi-Position Queries
> A multi-position query generalizes POS, SIZE to a table of positions, 
> allowing an
> arbitrarily large number of spatial position-based queries to be executed
> simultaneously.  In a typical scenario the user uploads a list of the 
> positions of
> their favorite objects, and executes a spatial cross match against some data
> table.  The multi-position query provides this simple spatial cross match
> capability.
>
> (full text at http://www.ivoa.net/internal/IVOA/TableAccess/tap-v0.2.pdf)
>
> Unless the NVO people working on this have found problems, this is still to 
> be part of the initial TAP spec (we'll find next week when we start to edit 
> the proposals into a unified draft).
>
> Therefore, I would expect that you might be able to use TAP installations for 
> cross-match sometime this year with prototypes and next year with production 
> services.
>
> Regards,
> Guy
>
>
> On 5 Sep 2008, at 16:14, Roy Williams wrote:
>
>> Dear DAL WG
>> 
>> I am writing to ask if the Skynode protocol will continue to be supported 
>> in the broader IVOA. Most of the current implementations seem to be at 
>> Johns Hopkins University -- is that true? Are there other skynodes out 
>> there that are and will be properly maintained?
>> 
>> A group of us in US-VO are developing an application (Vim) that handles 
>> multiple sky positions by running proximity (cone) searches against 
>> published catalogs. Thus a single click of the mouse can cause execution of 
>> a thousand separate cone searches against a single server. This can be very 
>> slow, and we would like to scale things up. We want a crossmatch service -- 
>> by which I mean no more than multiple cone searches. We want to do a 
>> thousand or a million cone searches in one "crossmatch" request.
>> 
>> Which of these paths should the Vim team follow:
>> 
>> (1) After years of discussion in this WG, I am still not seeing the 
>> emergence of anything like simple crossmatch in the TAP specification. So I 
>> guess we are still more years from widespread, solid implementation of TAP 
>> that can do crossmatch. Is that true?
>> 
>> (2) The Skynode protocol can do crossmatch already, and I wonder if this is 
>> the direction the Vim team should follow instead of waiting for TAP. 
>> However, before doing this, we would really like an assurance that there 
>> will continue to be multiple organizations supporting Skynode!
>> 
>> (3) The third way to get fast crossmatch would be to look through all the 
>> data center web pages looking for their own crossmatch services (eg 
>> [1][2][3]), and then build a custom interface from Vim to each data center.
>> 
>> Thank you for your help
>> Roy
>> 
>> 
>> 
>> [1] http://cas.sdss.org//dr6/en/tools/crossid/upload.asp
>> [2] http://irsa.ipac.caltech.edu/applications/Gator/GatorAid/Gator_Api.html
>> [3] http://vizier.cfa.harvard.edu/viz-bin/vizHelp?file.htx
>> 
>> -- 
>> 
>> California Institute of Technology
>> 626 395 3670
>