roadmap 2010-2011

[Francois Bonnarel]

Hi Pat,
Le 10/09/2010 21:35, Patrick Dowler a écrit :
> In the recent past we have had success in bringing more complex standards to 
> completion by breaking them down into manageable pieces and re-using existing 
> standards wherever possible. I would like to continue with this approach and 
> propose the following as a way forward. Obviously there are many things to 
> collectively consider and decide
>   
You wrote in your other mail that you thought this mail will be a little 
provocative. Bingo! Thank you anyway because  I think the DAL WG will 
eventually put some attention on SIA2.
 Apparently your assumption is c that SIA2 was not pushed to 
recommendation earlier because the standard as it is now is too complex.
 My opinion is different. Historically it seems that  IVOA DAL Working 
group was nether able to push more than one standard at a time... In the 
stone age we had Cone Search, (2001 ?)
 in the bronze age SIA1 (2002).
The beginning of history was devoted to SSA (2003/2007) and more recent 
ages to TAP (2007/2010).
After that came suddenly ObsTap by a strong commitment from the EXec 
(2009/2010).
Anyway ideas for SIA2 are there since a long time. There have been 
presentations and/or prototypes demos
at nearly all interops  since fall 2007. But with everybody paying 
attention  to TAP probably this was let in
the shadow.  There are documents which got  very little comments up to now.

 SIAV2 Analysis at Baltimore Interop time: 
http://www.ivoa.net/internal/IVOA/SiaInterface/SIA-V2-Analysis.pdf

 SIAV2 working Draft : 
http://www.ivoa.net/internal/IVOA/SiaInterface/WD-SIAP-2.0-20091104.pdf

The general landscape of DAL was described here:
DAL2 Service Architecture and Standard Profile Version 1.0 IVOA Note 21 
May 2010.

The main drawback of the latter document is that it doesn't integrate 
"ObsTap". But ObsTAp
is nothing else than the DataDiscovery method of the "Generic dataset" 
as it has been identified
by intense discussions in the Obstap separate discussion about one year ago.

Two points which are important to me:
       - before splitting the effort we should all look to what is 
there, comment and prototype or implement
and say what is wrong or complex with that. SIA2 is pushing the old SIA1 
one concepts and technologies to SSA level
at least. And it's easy to adapt SIA1services into SIA2.  The main 
criticism so far has been that  integrating  2D images
and cubes will be too complex and delay the recommendation. This can be 
discussed and maybe we can layer in time. I personnaly think than 
splitting everything  as you propose, Pat, will  be much longer.
      - SIA2 is really for images and parameters and methods are there 
to provide actual images (or cubes) not for
complex datasets or products which may contain or not images like ObsTap 
is able to do. I well tell more on this
in commenting Doug Tody's answer number 2 to your email

Cheers
François
...

> 1. remove all query parameters from SIAv2 and actively work on PQL
>
> 2. extract the "data linking" from SIAv2 and develop it as an independent 
> standard that can be used in multiple services
>
> 3. extract non-query parameters, error handling, VOTable usage, etc from SIAv2 
> and develop it as a base standard for all DAL services; this standard would be 
> called Data Access Layer Interface, or DALI :-)
>
> 4. pass work on the ImageDM to the DM-WG
>
> With this sort of approach, the SIAV2 specification will be the glue that pulls 
> the required elements together: DALI-sync, ImageDM, PQL, and DataLink.
>
> Likewise, SSAv2 would require at least DALI-sync, SpecDM, PQL, and DataLink. 
> When we get to making an update to TAP, it would also slim down and refer to 
> these and other standards. Other standards (SimDAP, for example) could be 
> defined to require DALI-sync, SimulationDM, and ADQL.
>
> * overly ambitious roadmap
>
> TAP (or DAL) extension schema (RFC Q4-2010): DAL+Registry need to begin work 
> on this immediately and finalise at Nara 2010.
>
> PQL (design/proto Q4-2010, RFC Q1-2011): work must start now, looking for 
> editor, author list will emerge during discussions
>
> DALI (design/proto Q4-2010, RFC Q1-2011): work must start now, looking for 
> editor, author list will emerge during discussions
>
> DataLink (design/proto Q4-2010, RFC Q1-2011): work must start now with mailing 
> list discussion of plausibility, use cases, and scope
>
> SIAv2 (prototypes and WD by Q2-2011): depends on ImageDM and above standards
>
> SSAv1.x (TBD): depends on whether fixes to SpecDM require it and on urgency 
> SSAv2 (TBD): depends on SpecDM, PhotDM, above standards, and requirements
>
>