How to implement a Xalan extension element

Question

I need an extension for Xalan to create URLs and anchors, as for example like:
<link>/this/is/some/url.html</link>
or
<link href="/this/is/some/url.html"><img src="/some/image.jpg"/></link>
Since the link extension should support to have further nodes as it's content, I thought it is a good idea to implement an extension element that returns a Node or an Element.
My problem is that I don't know how to create a new Nodeand add it to the stylesheet.
The Xalan objects throw an UnsupportedOperationException when I call createElement on the context or extension call element. Same for importNode when I create a new Node from another document instead.
What I could also do is to write an extension function that returns a string. But then I dont know how to use context.transformToString properly, because I want the sub-elements to be also transformed.
Any suggestions?
Dominik

Answer 1

Hi Dominik,
I'm not 100% sure, but I think the problem is the following:
According to the XSLT processing model the input document shoud be immulable.
So if you write a Java method which has a Node as a parameter you must not manipulate this node.
To do it nonetheless you might create a new Document and call importNode on the new document (Node editableNode = newDoc.importNode(immutableNode);). Then you can edit the new node and return it as you like.
But I'm afraid it is not possible (again due to the processing model) to have your stylesheet to process this newly created elements in the same transformation.
Best Wishes
esprimo
Edited by: esprimo on Sep 1, 2008 6:17 AM