The case for XML ADQL

[Tony Linde]

> and tested, but a pass-through of ADQL/text would be able to 
                    ^^^^^^^^^^^^^^^^^^^^

This is somewhat a contradiction. Pass-through implies that it is bypassing
the adql parser. In this case you would have to write SQL in the variant of
the database you are targeting. It would have to be up to a portal to
provide a text box for this and we'd have to provide a pass-through facility
in the DAL standard.

If you mean the ability to type in ADQL/s for parsing into the ADQL/x form
for transmission to a data centre and translation into local SQL then, yes,
this is something that power users will want and some portals will provide.

Cheers,
Tony. 

> -----Original Message-----
> From: owner-voql at eso.org [mailto:owner-voql at eso.org] On 
> Behalf Of Clive Page
> Sent: 05 February 2004 10:15
> To: voql at ivoa.net
> Subject: RE: The case for XML ADQL 
> 
> 
> 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
>