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Re: Concern: XQuery <> valid XML

From: Arnon Rosenthal <arnie@mitre.org>
Date: Thu, 01 Mar 2001 11:44:34 -0500
Message-ID: <3A9E7C72.26F51361@mitre.org>
To: www-ql@w3.org
I too appreciate all the hard work, and all the good judgement from the
committee. I feel the group is producing a well-founded basis that spans
requirements coming from several communities.

I think debates like the one we've just seen establish the case for both
sides. We should have two syntaxes, mapped (for consistency and
implementation ease) to the same semantic model. to strengthen that
case,  I'll mention two uses that did not appear in the previous thread.
In each case, there are real benefits to having a standard language in
that style.

1.  Need for a standard textual syntax.

To expand on Jeff Chapman's posting: 
> IMHO, the FLWR expressions bring great value to people who have to
> read/write XQuery documents the hard way, ie, with a text editor. ... 
> Most people will use GUIs to construct XQueries 

With SQL, application programmers often prefer to write textual syntax. 
Application queries need to be readable, too. For a complex query whose
specification requires many screens, the textual form is often
preferable.  Conclusion: There is a strong case for having one syntax
like FLWR.

2.  Need for a standard XML syntax. 

A standard XML syntax for queries would make it much easier for the
community to create a wide variety of query management tools.  By
standardizing the XML encoding, one could produce simple tools that see
queries themselves as queryable (and eventually, updatable) objects. For
example, there are many reasons to ask:  
What are all the queries in the Engineering department that reference
FOO?  that use FOO in a selection predicate?  that compute an
Average(BAR) for the entire input set? that restrict the input set and
then compute Average(BAR)?

For managing queries and profiles well, the syntax should emphasize
semantic units, in preference to syntactic ones.  

Arnon Rosenthal         arnie@mitre.org   	     (781)-271-7577
The MITRE Corporation   202 Burlington Road k/308,   Bedford MA
01730      USA
Received on Thursday, 1 March 2001 11:43:25 UTC

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