ADASS discussions

[Alasdair Allan]

> > Okay, I'd like to bring up my current pet peeve about the NVO cone search
> > standard (ie http://www.us-vo.org/metadata/conesearch/), which is that it
> > doesn't include either equinox or epoch.
> >
> > Both of these are vital for people wanting to do real science with the
> > catalogues. If the adopted standard doesn't include these things, people
> > doing galactic work won't use the interface because the retrieved
> > catalogues aren't going to be valid. We can _not_ assume J2000 for both
> > equinox and epoch, it just won't work!
> 
> Errm, as I understand it, the business of converting from one equinox to 
> another is straightforward and well understood.  So can we assume that the 
> cgi *query* is always J2000, and the catalogue database behind it converts to 
> that using standard libraries?  

Err, not exactly...
   
> As for the epoch, as most databases provide the viewing epoch for each 
> object, that should provide enough information? 

Depends, does your DB contain proper motion information for instance?

> It may create more work at the client end, but it makes it much easier 
> to publish databases, which encourages people to do so.

I might want to let Tim Naylor comment on this perhaps? He's currently
doing interviews but I think he might want to chip in here, I'll catch him
later today and ask him to throw a mail to the list about this one...

Its an important point, and something that people are currently ignoring.

> Agree lots.  Publishing data easily, using readily available (whether SOAP 
> and/or cgi-like querying and/or other) techniques, gives us a framework for 
> building all kinds of industry-wide tools, including but not limited to grids.

Agree lots... 
 
> However I would like to keep an eye on the inherant limitations of using 
> http: it's a simple request/response protocol, with no concept of session 
> state.  This makes it simple to use for small queries (which may be 90%? 99%? 
> of likely queries?) but really awkward to use for large queries.  State can 
> be added, yes, but it's a layer of extra stuff to add on *top* of http - 
> seems a waste given there's state in TCP/IP connections (*under* http)!

This is a valid point, but I'm not convinced that OGSA/OGSI is the answer
we're looking for...

Cheers,
Al.
-- 
Dr. A. Allan, School of Physics, University of Exeter