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From "Dumindu Pallewela" <>
Subject Re: [GSoC] XPath Project Status.
Date Wed, 06 Aug 2008 11:20:33 GMT

Please find my commnets inline.


On Tue, Aug 5, 2008 at 9:04 AM, Varuna Jayasiri <>wrote:

> Hi,
> The XPath engine now supports most of the generally used XPath expressions.
> Expressions such as path expressions, predicates, unions, conditional
> expressions, namespaces, etc have been implemented as we have discussed and
> planned.


> For example expressions such as the following could be evaluated:
> root//test:node[@*]/child[grandchild = /root/node1]
> /root//test:node[3]/child[@name = "abc"]
> And I would like to implement the complete XPath specification later, when
> I have time.
> XPath engine supports a set of expressions to be evaluated on streaming
> XML. However, since AXIOM does not support streaming XML the optimal level
> of performance cannot be achieved. Although XPath engine frees unwanted
> parts of the tree cached by AXIOM, it still stores certain information.

I guess free'ing unwanted nodes is done only when streaming is enabled? I
don't think we should free the process axiom trees even when streaming is
enabled. It should happen at axiom level, i.e., not caching the tree in the
first place. However it is good that you tried xpath processing with
free'ing, since it validates that your XPath engine should work even for an
streaming axiom implementation.

> The maximum advantage of streaming XPath can only be achieved by enabling
> streaming support at AXIOM level.

Well I think you should not worry about axiom caching. But make sure that
the required support is there for streaming. Basically, if you process the
nodes as axiom provides them, without going up the tree you should be fine.

Dumindu Pallewela
Cinergix - "Share, Reuse, Innovate"

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