Re: Sessions at Trieste

Hi Colleagues!

On Tue, 2008-05-13 at 10:30 +0200, Pedro Osuna wrote:
> I would ask some of you to send me possible answers to the RFC
> comments, as you have a better knowledge of the details. I will then
> introduce them in the system and sign like, e.g., "Pat Dowler for the
> VOQL-TEG, agreed by Chair", or something like that. Then, we could
> eventually discuss them in Trieste.

This is my first experience of replying to RFC, so I'll be guided by Pedro and you of more experience (Please!). These are my comments on Bob Hanisch's points. They still need editing because I'm obviously soliciting opinions (yours!). I'll try and generate other replies over the next day or so. I haven't edited them into the page as I wanted to gauge your opinions first. Pedro and Inaki, do you want to control the editing, as I'm sure others may want to add/amend/expand/delete.

I think first of all we should make the point that ADQL is a developing language. I don't think anyone on the TEG thought this would be the definitive release of the language. So, this current specification is a movement towards completion. Other, later versions will fill out the geometric and region side of things. We have to start somewhere.

Section 1.
I think we could accept these comments.

Section 2.3.2
We need to say something about STC. As the ADQL spec is not focused upon XML, it would be difficult to use STC-full, unless it is about what is emitted by the parser. But the parser is an implementation detail; and some may feel that a parser is not necessary: hence the concentration upon functions rather than operators. So we are back to STC-s. I cannot see anything in STC-s that allows it to be quoted easily in a query where details are extracted within the query; eg:

• Find all observed objects within 0.001 degrees of those
• observed objects which have a quality greater than 3
• and a redshift greater than 1.6 select s.obsra, s.obsdec, s.z, s.specid, s.targetname, s.quality from spectra as s where s.quality > 3 and s.z > 1.6 and CONTAINS( POINT( 'J2000', s.ra, s.dec ), CIRCLE( 'J2000', s.ra, s.dec, 0.001 ) ) = 1 ;

Please check this carefully (I'm not an astronomer and feel exposed here). Would this be an example that could not be covered by STC-s? I'm happy to be proved wrong, as usual.

Sections 2.3.2.2.3 and 2.3.2.2.4.
It was felt AREA, DISTANCE, LONGITUDE, LATITUDE and CENTROID would be useful extensions to the language, and may be the first of a number.

Section 2.3.2.2.5.6 INTERSECTS
I think we could accept these comments.

Section 2.3.2.2.5.11
I think someone else needs to answer this one. In my prosaic way, I think of a rectangle as polygon.

The spelling mistake can be corrected. The criticism over the level of sub-sectioning may be warranted.

OK. That's all for now.
Regards
Jeff

-- 
Jeff Lusted               tel: +44 (0)116 252 3581
Astrogrid Project         mob: +44 (0)7973 492290
Dept Physics & Astronomy  email: jl99-at-star.le.ac.uk
University of Leicester   web: http://www.astrogrid.org