Rethink the Constraint-based search Query from Registry interface

[Ray Plante]

Hi Paul,

On Fri, 8 Apr 2005, Paul Harrison wrote:
> I was really arguing for I guess, although I did not say it explicitly, 
> was that we have a separately defined registry query language, and a 
> simple one at that without all the XML syntax. 

Sorry if I misread initial note.  You do touch on a serious issue that 
many people have brought up, and that is having one standard depend on 
another.  As it is, the current RI is based on an old version of ADQL.  
This practice would probably not be so bad once our standards reached 
recommendation status and didn't change much, but we're in the most 
volatile period right now.  But you also mention the possibility of 
allowing us the freedom to branch off from ADQL to support our special 
needs.  This might be considered a Bad Thing if our special needs are 
really just an illusion.  Personally, I don't think we have special needs 
beyond what ADQL needs to do, but I could be convinced otherwise.  

The other important point you make is the desire to drop the XML syntax.  
That is, you would like to see a string syntax sent over the wire.  What 
is your take, then, on the parsing issue (what I listed as "RP.1.2   It 
should be easy to parse in multiple, commonly-used languages")?  One 
problem with ADQL/s was that for a long time, the only parser existed in 
C#; to convert to ADQL/x, one had to call a web service at STScI.  
Recently (with no small effort by myself and Tom McGlynn), we wrote 
one in Java.  ADQL/s is about the level of complexity we're going to need 
(if you include region support).  If we go with a string syntax, we reduce 
the number of languages that are effectively supported.  Is this worth it?  

cheers,
Ray