Re: large XML files

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Mon, 08 Feb 2010 14:08:40 -0500
Message-ID:
<hkpnfp$ctq$1@news.albasani.net>
Lew wrote:

I know from a recent project that it's next to useless to match XPath
expressions with a SAX parser.


Tom Anderson wrote:

In what sense? That it justs builds a DOM tree behind the scenes?


In the sense that for XPath to work, there has to already be a DOM for it to
search, or else you have to forego built-in XPath processing. In that recent
project they attempted to cache results from XPath expressions that were built
by manually matching the expression with data from the streamed input. When
that missed, they had to either re-read the whole input or go ahead and build
a DOM regardless. The complexity and time cost of manual XPath handling and
the frequency of misses presented a rather intractable barrier to the approach.

That's only a single data point, of course. I don't rule out the possibility
that another approach to blending SAX and XPath could work. Had it been up to
me, I would have abandoned XPath for that application and just used SAX or
StAX to build a domain-specific object model, not a DOM, and directly
referenced items from that model.

--
Lew

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