Appropriate use of XPath & xerces

["Helzer, Mark" <Ma...@adp.com>]

Hi all,

Documentation and the list archive say that you can use a Xerces DOM document if you wish to update your document while using XPath. Or at least something similar, perhaps I'm misconstruing the intent.

Here is what I would like to do:

I have an existing app using Xerces DOM where I create/update an XML document.  Looping through a cvs file, extracting the data and updating or adding elements in the XML as needed.  This was working fine until the data and the # of elements were smaller.  After adding new types of data performance has gone in the hopper.

I would like to be able to use XPath to locate nodes for update,  if the node is not found I would add the new element and refresh the document tree.

Perhaps this is not how XPath is intended to be used?

Mark Helzer



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Re: Appropriate use of XPath & xerces

[David Bertoni <db...@apache.org>]

On 5/18/2010 5:28 PM, Helzer, Mark wrote:
> Hi all,
>
> Documentation and the list archive say that you can use a Xerces DOM document if you wish to update your document while using XPath. Or at least something similar, perhaps I'm misconstruing the intent.
>
> Here is what I would like to do:
>
> I have an existing app using Xerces DOM where I create/update an XML document.  Looping through a cvs file, extracting the data and updating or adding elements in the XML as needed.  This was working fine until the data and the # of elements were smaller.  After adding new types of data performance has gone in the hopper.
>
> I would like to be able to use XPath to locate nodes for update,  if the node is not found I would add the new element and refresh the document tree.
>
> Perhaps this is not how XPath is intended to be used?
Unfortunately, you haven't provide nearly enough specific information to 
answer your question.

In general, Xalan-C's wrapper around the Xerces-C DOM is not that 
efficient for modifying a document. In particular, it's a requirement 
you rebuild the wrapper when you make modifications, so it would be 
better if you evaluated all of the XPath expressions at once, then made 
all of the modifications.

If you could post some code snippets, and be more specific about exactly 
what changes are causing the performance problem, that would be helpful.

Also, this is exactly the kind of manipulation that XSLT was designed to 
do, so you might consider writing a stylesheet to do this transformation.

Dave