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   Re: [xml-dev] Streaming XML (WAS: More on taming SAX (was Re:[xml-dev] A

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On Mon, 2004-12-27 at 12:00 -0800, Daniela Florescu wrote:
> >     I've thought about using an XPath tracker in error reporting to
> >     my library, which would be very simple to add at this point, and
> >     it's necessary, I think because the document locator loses
> >     meaning when I chain together a bunch of SAX filters.
> ..........
> >
> >     In any case, I'm reading through some of the other articles
> >     you've been posting. This is a very interesting discussion.
> I read with great interest the whole discussion about XML streaming and 
> SAX,
> and I have to admit that I am very confused by it.
> Could you guys please try to clarify for me the answer to the following 
> question: instead
> hand coding steaming applications using SAX, couldn't you write some
> XQuery code (with external functions probably) to do the same thing ?
> Did you try at least ? Did you try and fail ? If yes, why did it fail ?

I've observed XQuery for a very long time.  I have never liked it (a
fact I've written about several times).  I am not about to re-hash the
whole recent XQuery debate Edd so nicely summarized.  Others in that
thread (Bray, Carlisle, and even Kay at times, among others) I think
have expressed very eloquently what I might like to say on the matter.

There's pretty much no chance of my using XQuery, nor many of my
colleagues, but I've lately surprised myself by frequently losing
patience with even XSLT.  I'm the one who is usually evangelizing XSLT
to Pythoneers (among whom the prevailing response I've observed is

My own personal regret is that I have spent so much of my energy since
1997 implementing W3C specs and such with excessive literal-mindedness,
including DOM, XPath, XSLT, etc.  Developments such as SOAP, XQuery and
DOM L3 finally made it clear to me that the W3C* and many other such
organizations seem bent on maximum complexity in XML.  Many of my fellow
Pythoneers tried to convince me earlier to plump for simplicity and
Python idiom.  Amara XML Toolkit represents the fact that I'm just now
coming around to properly appreciating their point of view.

* This is a generalization, and not meant to ignore that there are many
forces for sanity at work in the XML consortia.  Those forces too often
seem to lose the battle for imprimatur, but they need not lose the
battle for running code.

> Other question: why do you people care about "perfect" streaming, i.e. 
> streaming
> with zero memory consumption ?

No one said they were.

> Between perfect streaming and total 
> materialization
> there is a world of possibilities in between, where materialization 
> happens, but only
> restricted to the minimum amount of data required to compute the 
> answer, and only
> for the minimum amount of time necessary to compute the correct answer.

Sure, which is where the programmer wields his practiced hand, no?

> But anyway, for those interested in streaming processing XML, the 
> database
> research might come in handy. There have been several studies of the 
> problem in the
> literature. For example you could find some of it at
> http://citeseer.ist.psu.edu/
>   searching for "streaming XML"; starting from there you might find some 
> interesting papers.

As we've clarified here.  We're talking far less basic science and
engineering.  We're talking more rough consensus among fellow


Uche Ogbuji                                    Fourthought, Inc.
http://uche.ogbuji.net    http://4Suite.org    http://fourthought.com
Use CSS to display XML - http://www.ibm.com/developerworks/edu/x-dw-x-xmlcss-i.html
Full XML Indexes with Gnosis - http://www.xml.com/pub/a/2004/12/08/py-xml.html
Be humble, not imperial (in design) - http://www.adtmag.com/article.asp?id=10286
UBL 1.0 - http://www-106.ibm.com/developerworks/xml/library/x-think28.html
Use Universal Feed Parser to tame RSS - http://www.ibm.com/developerworks/xml/library/x-tipufp.html
Default and error handling in XSLT lookup tables - http://www.ibm.com/developerworks/xml/library/x-tiplook.html
A survey of XML standards - http://www-106.ibm.com/developerworks/xml/library/x-stand4/
The State of Python-XML in 2004 - http://www.xml.com/pub/a/2004/10/13/py-xml.html


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