XML parsing memory overhead concerns (fwd)

Sat Dec 18 17:19:21 GMT 1999

Paul,

James posted the answer to your concern a while
back... (it took me a while to grok what he
was saying).   Sean's description is correct,
only he didn't mention "how" you do it with expat.
James describes this below.  You only send "part" 
of the XML stream at any given time, it fires 
callbacks filling up your event buffer, as
Sean describes.  Evidently expat handles
"restarting" mid element..

Clark

---------- Forwarded message ----------
Date: Fri, 17 Dec 1999 14:48:06 +0700
From: James Clark <jjc at jclark.com>
To: Clark C. Evans <clark.evans at manhattanproject.com>
Cc: Paul Miller <stele at fxtech.com>, xml-dev <xml-dev at ic.ac.uk>
Subject: Re: XML parsing memory overhead concerns

"Clark C. Evans" wrote:

> Anyway, given a SAX event source, pushing
> the entire document his way, I don't see
> how a single threaded solution is possible.
> 
> And, from the expat declaration of setElementHandler,
> which requires both a StartElementHandler and an
> EndElementHandler, I assumed that expat works in
> a similar (if not identical) manner.

Expat doesn't work like SAX.  Clark Cooper has written a nice article
explaining expat's API:

  http://www.xml.com/pub/1999/09/expat/index.html

With SAX, the application calls parse once per document; the parser
makes a call on an InputStream to get each chunk of input.  With expat,
the parser doesn't make any calls to get input; rather the application
calls XML_Parse() arbitrarily many times for a single document, each
time passing it another chunk of the input.

James

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