Re: [xsl] Joining Multiple XML using XPath API of XALAN

[Joseph Kesselman <keshlam at us dot ibm dot com>]

>What should I write in my stylesheet (XSL) so that it
>gets the XML DOM reference in an XSL variable????

You can't do this in XSLT alone. You need to write some code.

>Is the work in above going to be more than using the
>importNode(...) and insertBefore(...) function from
>Document and Node classes respectively to merge the
>XMLs???

If you can merge them before passing them to XSLT, you can use those 
approaches. You can't use them within XSLT; there is a basic assumption 
that each source document is immutable for the duration of the 
stylesheet's execution.

I see two possible approaches here.


1) This one I'm sure would work: Write an extension function (see Xalan's 
documentation on extension functions), and architect some way in your own 
code for that function to find the DOM(s) you want to access. Pass the 
Document nodes to Xalan as the return values of this function, and we'll 
wrapper it and Do The Right Thing. Possible efficiency issue: If you 
expect to access the same DOM multiple times, you should probably call 
your extension only once and assign the returned value to an XSLT 
variable.

For information about writing Xalan extensions, see 
http://xml.apache.org/xalan-j/extensions.html


2) I'm not sure of this one since I haven't tried it in a long time, 
but...  it's possible to pass a DOM node into Xalan as a parameter, via 
the TrAX APIs, before running the stylesheet. Essentially, this is 
equivalent to assigning the object to a variable before stylesheet 
processing starts -- though of course your stylesheet has to be written to 
expect and use that parameter. The thing I'm not certain of is whether 
this will recognize the DOM node and automatically give Xalan full access 
to the DOM tree (convert it to a nodeset), or if Xalan will treat it as a 
"non-XSLT object" and force you to pass it through an extension before you 
can see its contents.  Can't hurt to try...

For information about parameters, see 
http://xml.apache.org/xalan-j/usagepatterns.html#params

______________________________________
Joe Kesselman  / IBM Research

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