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Re: Why are XQueries relegated to 2nd class status?

From: Jonathan Robie <Jonathan.Robie@SoftwareAG-USA.com>
Date: Wed, 28 Mar 2001 11:33:36 -0500
Message-Id: <>
To: Tony Coates <Tony.Coates@reuters.com>
Cc: www-xml-query-comments@w3.org, w3c-xml-query-wg@w3.org
Dear Tony,

This is a response to the following message, which you posted to the XML 
Query Working Group's comments list:


The XML Query Working Group has approved the following response:

  > I am disappointed that the syntax that
  > has been published is SQL-based rather
  > than XML-based.

Most people in the Working Group feel that the XQuery syntax is easier to 
read and write than an XML-based syntax would be. We also are creating an 
XML-based syntax that has precisely the same information content as XQuery.

It is probably not accurate to call XQuery SQL-based. Please note that FLWR 
is only one of the expression types in XQuery. Another expression type is 
an XML path expression. The compositionality of XQuery comes from a close 
relationship to the structure of the grammar of OQL, giving it a 
grammatical structure that allows it to take full advantage of the closure 
of operations in the algebra.

  > In a world where there now are
  > really good XML editors available,
  > non-XML-based syntaxes do little except
  > relegate files to second-class status,
  > and this is what worries me most about
  > FLWR.

I believe that XSLT is a very successful programming language which uses an 
XML instance syntax. However, we feel that the conciseness and readability 
of XQuery is greater than it could be in an XML notation.  There is no big 
rush in the programming community to create XML instance notations for 
Java, JavaScript, Visual Basic, or C++, and attempts to create XML versions 
of SQL have not been particularly successful.

  > the problem with FLWR is that it
  > requires a separate, non-XML parser.

First off, I believe that implementations that use only the XML syntax 
should be considered fully conforming.

Second, we provide two grammars for generating a parser, and this should 
make it relatively straightforward for many programmers to implement a parser.

As you point out, the XML-based syntax for XQuery is easier for machines to 
process and perhaps also to generate. If the two syntaxes have a one-to-one 
mapping, that should make it possible to convert queries to use whichever 
syntax is more convenient in a given environment.

We appreciate your feedback on the XML Query specifications. Please let us 
know if this response is satisfactory. If not, please respond to this 
message, explaining your concerns.

Jonathan Robie
On behalf of the XML Query Working Group
Received on Wednesday, 28 March 2001 11:32:04 UTC

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