there is no either or with Cocoon and Xalan. The first one is an XML publishing framework (http://xml.apache.org/cocoon/index.html), the second one an XSLT processor. Cocoon uses normally Xalan, but you can use any other Java XSLT processor too (I think).
What are your "coding issues"? You can setup quite fast a business logic in the sitemap, but maybe you don't want to. An easy transformation in the sitemap looks like the following:

<map:match pattern="index.html">
  <map:generate src="index.xml"/>
  <map:transform src="index.xsl"/>
  <map:serialize type="html"/>
</map:match>

<map:match pattern="**.html">
  <map:generate src="{1}.xml"/>
  <map:transform src="somestylesheet.xsl"/>
  <map:serialize type="html"/>
</map:match>

   URI request                                 XML source document
-----------------------------------------------------------------------
http://host:port/mountpoint/index.html    ->   index.xml
http://host:port/mountpoint/foo/bar.html  ->   foo/bar.xml

--
Steven Noels                            http://outerthought.org/
Outerthought - Open Source, Java & XML Competence Support Center
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