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From Rex Wang <rwo...@gmail.com>
Subject Re: [taglibs] XPath support
Date Wed, 22 Dec 2010 03:46:09 GMT
2010/10/3 Jeremy Boynes <jboynes@apache.org>

> On Jul 15, 2010, at 12:19 AM, Henri Yandell wrote:
>
> > On Wed, Jul 14, 2010 at 8:45 PM, Jeremy Boynes <jboynes@apache.org>
> wrote:
> >> On Jul 12, 2010, at 7:04 PM, Jeremy Boynes wrote:
> >>
> >>> I'm going to ping Xalan about the increase in time taken as expressions
> are evaluated as I would assume I'm doing something silly.
> >>
> >> I looked into the Xalan implementation and the problem appears to be in
> creation of the DTM used by the underlying implementation. To evaluate the
> expression it walks up the DOM tree to the parent and then iterates forward
> over the tree until it reaches the initial context node. This leads to a
> linear increase in execution time as the context node progresses through the
> NodeList from the <forEach>.
> >>
> >> I changed <x:forEach> and <x:out> to use Jaxen and did not see this
> issue. The execution time for xpath evalutation over 1000 iterations was
> constant and substantially faster than with Xalan: total of 62ms reparsing
> each time or 21ms if precompiled, down from 1800ms.
> >>
> >> In light of this I'd like to propose we switch to Jaxen and add it as a
> dependency.
> >
> > Absolutely: +1
> >
> > Great work :)
>
> I've not committed these changes as the latest version of Jaxen is not
> available in the Maven repo and there did not appear to be much interest in
> doing so. We might be able to get similar improvements using JXPath.
>
>
Could we start the release process without resolving this performance issue?

If not, the servicemix bundled jaxen
http://repo1.maven.org/maven2/org/apache/servicemix/bundles/org.apache.servicemix.bundles.jaxen/1.1.1_1/
might be a good choice as the dependency.

-Rex



> --
> Jeremy
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-- 
Lei Wang (Rex)
rwonly AT apache.org

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