RE: The case for XML ADQL

From: Clive Page <cgp-at-star.le.ac.uk>
Date: Thu, 5 Feb 2004 10:14:49 +0000 (GMT)


On Thu, 5 Feb 2004, Tony Linde wrote:

> Anyone who wants to provide a text input service will have to write a parser
> that translates from the text form into the standard xml form.

I think it will be essential to have converters in both directions between ADQL/text (alias SkyQL) and ADQL/XML. We have already found that it is exceedingly difficult to test software which requires fully formed XML as its input, so the testers need to be able to input ADQL/text. I think power users who are already familiar with SQL will want to be able to continue using it (or something very similar) - they will not take kindly to instructions to learn ADQL/XML. Thirdly, the ADQL/text form has very limited extensibility: if some backend can provide additional facilities such as stored procedures/user-defined functions, then these would be unusable from ADQL/XML until the parsers have been modified and tested, but a pass-through of ADQL/text would be able to use these extensions immediately, and they might (if suitable) be incorporated into the standard at some future date. A living language needs a simple route for growth.

-- 
Clive Page
Dept of Physics & Astronomy,
University of Leicester,    Tel +44 116 252 3551
Leicester, LE1 7RH,  U.K.   Fax +44 116 252 3311
Received on 2004-02-05Z11:15:07