Streaming XPath Support

It is a nice feature. Are there any performance data
available for the
improvements based on streaming XPath, like throughput,
latency, etc?

As to the XSD validation, does it support full streaming
based
validation? For example, full support for validation in SAX
mode without
the need to keep tree.

Thanks,
Stanley
-----Original Message-----
From: Daniel Veillard [mailto:veillardredhat.com] 
Sent: Tuesday, December 19, 2006 1:41 PM
To: Stanley Poon (spoon)
Cc: xmlgnome.org
Subject: Re: [xml] Streaming XPath Support

On Tue, Dec 19, 2006 at 11:01:45AM -0800, Stanley Poon
(spoon) wrote:
> My understanding is that the current support is mainly
for the 
> Selector in XSD.

  right though we also use it to speed-up simple XPath
queries

> Are there any plan to enhance the support for streaming
Xpath such as 
> //, *, simple predicates, etc.

  I take patches! Again that's something which Kasimier
worked on and a
bit orphaned at this point.

> Also, is this internal feature added
> mainly for performance and for reducing memory usage?

  to be able to stream XSD validation without keeping trees
around.

> Is the current implementation based on some finite
state machine 
> approach with some path sharing?

  based on automatas, see pattern.c in the sources.

Daniel

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On Tue, Dec 19, 2006 at 03:46:59PM -0800, Stanley Poon
(spoon) wrote:
> It is a nice feature. Are there any performance data
available for the
> improvements based on streaming XPath, like throughput,
latency, etc?

  No. We needed the feature, that's why it was implemented,
not a 
focus on performances.

> As to the XSD validation, does it support full
streaming based
> validation? For example, full support for validation in
SAX mode without
> the need to keep tree.

  yes see
   xmllint --stream --schemas ....
This is part of the regression tests, see xmllint.c code to
find how to
hook XSD validation on top of the SAX2 API

Daniel

-- 
Red Hat Virtualization group http://redhat.com/v
irtualization/
Daniel Veillard      | virtualization library  http://libvirt.org/
veillardredhat.com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ |
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