Recursively Merging 2 XML files with XSLT

Question

Hi there, I'm having a problem with merging a couple of XML files. I've found a few examples of merging on-line but none that really help.
Basically I have an XML file which is written out by my Java program that looks something like this:
<alldata>
   <data val="xx">
      <data val="yy">
         <data val="ss"></data>
      </data>
   <data val="gg"></data>
</alldata>The number of children and siblings can change by the way.
Therefore in the XSLT document I'm displaying the data recursively, i.e.
<tr><td><xsl:value-of select="@val"/></td></tr>
<xsl:for-each select="*">
   <xsl:call-template name="itself"></xsl:call-template>
</xsl:for-each>This all works fine, but I now need to do a side by side comparison with another XML document that has exactly the same structure, but could have different values. I'm not sure how to do this, perhaps using the same recursive code and using a sort of pointer to where you are in the 2nd XML file (see below), but I've no idea how to go about this?
<tr><td><xsl:value-of select="@val"/></td>
       <td><xsl:value-of select="<2nd documents @val>"/></td>
</tr>
<xsl:for-each select="*">
   <xsl:call-template name="itself"></xsl:call-template>
</xsl:for-each>Output:
xx    xy
yy    yy
ss   ss
gg   hhDoes anybody have any suggestions or help on how to achieve this?
Cheers
Dan

Answer 1

I posted the same question on the xsl-list message list and got a working solution - here it is in case anyone else has the same problem:
<xsl:variable name="a" select="document('doc1.xml')//data"/>
<xsl:variable name="b" select="document('doc2.xml')//data"/>
<xsl:template match="/">
     <table>
       <xsl:for-each select="$a">
         <xsl:variable name="p" select="position()"/>
         <tr>
           <td><xsl:value-of select="@val"/></td>
           <td><xsl:value-of select="$b[$p]/@val"/></td>
         </tr>
       </xsl:for-each>
     </table>
</xsl:template>Cheers
Dan