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RE: [www-ql] <none>

From: Ingo Macherius <macherius@darmstadt.gmd.de>
Date: Fri, 2 Mar 2001 18:05:46 +0100
To: "Www-Ql@W3. Org" <www-ql@w3.org>
Message-ID: <NDBBKNAAEKOBBDPKKDDCKEKGDIAA.macherius@darmstadt.gmd.de>
Jonathan,

I think you are twisting facts a bit. Algebra is preceding FLWR-XQuery in
both time and completeness. Quilt preliminarily published many things which
are results of Algebra. And just because Algebra voluntarily decided to drop
early publication in favour of maturity, i don't think it is very fair to
argue it should now adopt to XQuery.

> the same period, and we were talking to each other, I think that the two
> are broadly compatible. For any incompatibility we identify, there is no

Broadly ? I'm a bit afraid until I can hear "fully".

> general principle that tells us whether XQuery should change or
> the Algebra
> should change to support it. That's something the Working Group has to
> decide on an issue-by-issue basis.

There has been much more verification on the soundness of Algebra, using
formal methods and use cases, then for FLWR-XQuery. There is a significant
personal overlap between the authors of Quilt/FLWR-XQuery and the W3C-WG,
and Quilt profited a lot from Algebra discussions. Given this, it is the
"Bringschuld" (debt to be discharged at creditor's domicile) of XQuery to
move first.

> However, it is not really the egg out of which XQuery hatched,
> XQuery came
> from Quilt, which was not based on the Query Algebra. I was very

I think this is a bug, not a feature.

> pleased to
> see how easy it was to map XQuery onto the Query Algebra.

Sounds promising. Do you have a URL for that mapping description ? And when
do you expect the inverse mapping, Algebra->FLWR-XQuery, to be completed ?

Regards,
	++im

> -----Original Message-----
> From: Jonathan Robie [mailto:Jonathan.Robie@SoftwareAG-USA.com]
> Sent: Thursday, March 01, 2001 11:41 PM
> To: Ingo Macherius; Www-Ql@W3. Org
> Subject: RE: [www-ql] <none>
>
>
> At 12:07 AM 3/1/2001 +0100, Ingo Macherius wrote:
>
> >Hm, isn't the tail waiving with the dog here ? XQuery has to prove
> >compliance with Algebra by giving a mapping, not the other way round ...
>
> I believe the real requirement is for XQuery and the algebra to be
> completely compatible. Since the language and the algebra were
> defined over
> the same period, and we were talking to each other, I think that the two
> are broadly compatible. For any incompatibility we identify, there is no
> general principle that tells us whether XQuery should change or
> the Algebra
> should change to support it. That's something the Working Group has to
> decide on an issue-by-issue basis.
>
> > > We all seem to agree that for humans FLWR is easier to
> > > understand than XML. Since at this stage people need to understand the
> > > semantics and the expressive power of the proposed language,
> FLWR seems to
> > > be a message format that is superior to XML :-)
> >
> >Tail waving with dog again. To put it another way: now we have
> the FLWR-hen,
> >the majority of the XML community becomes aware of the
> Algebra-egg. This is
> >a very good thing, given the long silence regarding XML Query.
>
> The Algebra is a Very Good Thing, and brings great benefit to XQuery.
> However, it is not really the egg out of which XQuery hatched,
> XQuery came
> from Quilt, which was not based on the Query Algebra. I was very
> pleased to
> see how easy it was to map XQuery onto the Query Algebra.
>
> Jonathan
>
>
Received on Friday, 2 March 2001 12:04:03 GMT

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