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Re: Which query language to use for XML?! (fwd)

From: Murali Mani <mani@CS.UCLA.EDU>
Date: Tue, 15 May 2001 09:42:01 -0700 (PDT)
To: <www-ql@w3c.org>
Message-ID: <Pine.SOL.4.33.0105150917400.17198-100000@panther.cs.ucla.edu>

This is in response to Davy's mail, to which Paul Cotton, and Evan Lenz
replied. I had replied slightly before. XQuery and the XML version of
XQuery might be slightly closer to me than XPath (in that I tried to look
into some aspects of XQuery and not into XPath 1.0).

In spite of some knowledge of these, I would say XPath 1.0 is what we
might want to use at this point of time -- I *strongly* suspect there
might (not very sure) be some disagreement between XPath semantics and
XQuery Algebra semantics -- for example, count (algebraImpl (pathExpr))
need not always be equal to count (xpathImpl (pathExpr)) -- I think this
and some other disagreements *should* be resolved/understood before I
would use the algebra -- these disagreements mainly arise because algebra
is supposed to return a hedge (ordered list of trees) as opposed to a
node-set (unordered set of trees) -- returning a hedge is a *novel*
concept, this can be supported indirectly in existing models -- but direct
support as in the algebra i think is *needed*.

I personally fully support XPath 1.0 semantics for the operations they

I am a user of XML technologies over the last one year especially, and I
think I kind of understand xml structures, xml schemas for data modeling,
and path expressions as in xpath 1.0 to some depth at this point of time.

<warning>speaking for himself only</warning>

regards - murali.

---------- Forwarded message ----------
Date: Wed, 9 May 2001 01:49:47 -0700 (PDT)
From: Murali Mani <mani@cs.ucla.edu>
To: Davy Toch <datoc@gengenp.rug.ac.be>
Subject: Re: Which query language to use for XML?!

I think almost all query efforts are combinining into XQuery and also
XSLT. I am very familiar with XPath 1.0 (and also the requirements for
XPath 2.0) -- XPath which is the basis for both XQuery and XSLT will be
sufficient for most purposes -- it also has order support based on
document order.

However XQL, XML-QL have combined into XQuery. (XQuery has Don Chamberlin
from SQL, Jonathan Robie from XQL, and Dana Florescu from XML-QL).

But XPath 1.0 is what I would use at this point, and i think it is *very*
simple and sufficient for several purposes (like yours seems to be). Also
you have good implementations in Xalan (from xml.apache.org).

hope this helps.

regards - murali.

On Wed, 9 May 2001, Davy Toch wrote:

> Hello,
> I have a small question. I'm working on a thesis which involves
> extracting data from an xml-data file. This extraction needs to be done
> with Perl (scripting language), which has support for querying with XQL,
> XPATH, .... My problem is which querying language to use (XQL, XPATH,
> XML-QL, ...), because they all seem to do the same thing, that is
> querying XML-documents.
> Thanks in advance.
> --
> ==================================================================
> Davy Toch
> DEPARTMENT OF GENETICS                         Fax:32 (0)9 2645349
> UNIVERSITY OF GENT, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium
> Vlaams Instituut voor Biotechnologie                           VIB
> mailto:datoc@gengenp.rug.ac.be      http://plantgenetics.rug.ac.be
> ==================================================================
Received on Tuesday, 15 May 2001 12:42:14 UTC

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