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RE: [Question] How to do incremental parsing?

• From: Jeff Lowery <jlowery@s...>
• To: "'Xu, Mousheng (SEA)'" <Mousheng.Xu@s...>,"'xml-dev@l...'" <xml-dev@l...>
• Date: Wed, 04 Jul 2001 10:33:24 -0700

For large documents where:
	a) the target data is sparse (bits scattered throughout the large
document), and
	b) the location of the data is known (what branch it hangs off the
tree),
then you might get the best performance, speed- and memory-wise, using a
pull-based parser like kXML (www.enhydra.org). With a pull-based parser, you
lightly skip over the nodes you're not interested in until you find a node
that has content you're looking for. 

Caveats: 
1) I don't know if anyone has actually done performance testing to verify
the above claim, and 
2) kXML, at least, has some limitations, quote:
- kXML does not support user defined (external) entities. 
- The doctype declaration is not parsed. However, a corresponding "legacy
event" is generated by the    parser, so application programmers are able to
parse the doctype declaration themself 

> -----Original Message-----
> From: Xu, Mousheng (SEA) [mailto:Mousheng.Xu@s...]
> Sent: Tuesday, July 03, 2001 5:27 PM
> To: 'xml-dev@l...'
> Subject: [Question] How to do incremental parsing?
> 
> 
> Dear all,
> 
> A problem of all the current XML parsers is that they at 
> least read the
> whole XML document into the input stream, which can consume a 
> lot of memory
> when the XML is big (e.g. 1 GB).
> 
> One way to get around the problem would be to read the XML 
> file into memory
> gradually and when needed. I would like to build such a DOM 
> parser, but I am
> not familiar with the design of the Xerces XML parsers. Could 
> someone give
> me a suggestion on how to tackle on the problem? The most 
> critical part
> would be the method to parse an element. If reading the whole 
> document into
> memory is inevitable, then I would like to borrow the method 
> which parse the
> input stream to get the next element.
> 
> Your help is highly appreciated.
> 
> Thanks in advance.
> 
> -- Mousheng Xu 
> 
> 
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