[xsl] Is it OK for xsl:output to affect the construction of an unserialized result tree?

[Elliotte Rusty Harold <elharo@xxxxxxxxxxxxxxx>]

This is a practical issue relating to proposed Xalan-J bug:

http://issues.apache.org/bugzilla/show_bug.cgi?id=30197

Consider this stylesheet:

<?xml version="1.0"?> <xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
				  <!-- test a stylesheet that use 
method="text" -->
  <xsl:output method="text"/>

<xsl:template match="/">
    <element1>12345</element1>
    <element2>67890</element2>
    <element3/>
	<element4>0987654321</element4>
	<xsl:comment>test</xsl:comment>
	<xsl:processing-instruction name="test">PIs are not treated 
as literals in
XSLT?</xsl:processing-instruction>
  </xsl:template>

</xsl:stylesheet>

Suppose we transform a DOM Document, XOM document, SAX InputSource or 
some other such representation of an XML document. Furthermore 
suppose that instead of serializing the output as a stream or a 
string we create another DOM document, XOM document, etc. Should the 
xsl:output element have any effect?

My claim is that it should not. Anything said in the xsl:output 
element applies only when the document is serialized to a an actual 
XML document represented as a sequence of characters or bytes, not 
before. This is what earlier versions of Xalan did. Faced with this 
case,  they would produce a result tree containing six child nodes of 
different kinds,
element, comment, and processing instructions.

However, in the last few versions, Xalan produces a single text node 
containing all the element content. The elements, comments, and 
processing instructions should be reduced to plain text only when the 
document is serialized, not before. In my opinion, Xalan appears to 
be jumping the gun when the output method is text and incorrectly 
assuming that it can generate a single text node. However, at least 
on of the Xalan developers disagrees with me, and thinks this is 
acceptable and indeed desirable behavior.

What does everyone else think? I've always assumed xsl:output only 
applied in serialization, not result tree construction but Joe 
Kesselman thinks the spec language is at best ambiguous on this 
point. Interpretations from working group members would be 
particularly helpful.

One thing that worries me is that if this is made optional (because 
xsl:output is support clearly optional according to the spec) then 
this becomes yet another point where different implementations behave 
differently with no clear way for client code to figure out what's 
likely to happen.

--

  Elliotte Rusty Harold
  elharo@xxxxxxxxxxxxxxx
  Effective XML (Addison-Wesley, 2003)
  http://www.cafeconleche.org/books/effectivexml            
  http://www.amazon.com/exec/obidos/ISBN%3D0321150406/ref%3Dnosim/cafeaulaitA