I have two XML files, (provided by another application) that needs a comparison. Some of the parameters (especially in the ifIndex section) does change from time to time. Here is a snippet from one of the files..

<tmsinfo>
 <rtr name="router1">
  <ifIndex value="127">
   <ifDescr value="FastEthernet0/0/1.87"/>
   <ifSpeed value="100000000"/>
   <ipAdEntIfIndex value="10.0.0.1"/>
  </ifIndex>
  <ifIndex value="32">
   <ifDescr value="Serial0/1/1:0"/>
   <ifSpeed value="256000"/>
   <ipAdEntIfIndex value="10.0.0.2"/>
   <locIfDescr value="SomeLink"/>
  </ifIndex>
.
.cut
.
  <ifIndex value="146">
   <ifDescr value="FastEthernet0/0/1.95"/>
   <ifSpeed value="64000"/>
   <ccarConfig ccarDir="1">
     <ccarIndex value="1">
      <AclNo value="2160"/>
      <ExtLimit value="8000"/>
      <Limit value="8000"/>
      <Rate value="64000"/>
     </ccarIndex>
   </ccarConfig>
   <ccarConfig ccarDir="2">
     <ccarIndex value="1">
      <AclNo value="3160"/>
      <ExtLimit value="8000"/>
      <Limit value="8000"/>
      <Rate value="64000"/>
     </ccarIndex>
   </ccarConfig>
   <ipAdEntIfIndex value="10.0.0.3"/>
  </ifIndex>
 </rtr>
</tmsinfo>
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What I have tried so far is to load one file into a twig and use the TwigHandlers on the second file to do the comparison on if the information inside the ifIndex has changed.

#!/usr/bin/perl -w

use strict;
use XML::Twig;

my $router=$ARGV[0];
my $fname="$router.xml";

my $RoutersLastState = XML::Twig->new(); #Last received State
### Load Last State/s
 $fname="$fname.last";
 $RoutersLastState->parsefile($fname); 
 print "Loaded Last State\n";

my $RoutersCurrState = XML::Twig->new(  TwigHandlers => { ifIndex => \
+&find_diff },
                     ); #Current State
### Load Current State
 $RoutersCurrState->parsefile($fname); 
 print "Loaded Current\n";

 my $outfname="$fname.changes";
 open (FH,"> $outfname");
 $RoutersCurrState->print(\*FH,'indented');
 close (FH);
 
 exit;
 
 sub find_diff{
  my( $twig, $ifindex)= @_;
  my $indexval=$ifindex->att('value');
#  print "$indexval\n";
  foreach my $oldindex ($RoutersLastState->root->first_child('router')
+->children('ifIndex')){
   my $oldindexval=$oldindex->att('value');
   print "$indexval\t$oldindexval \n";
    if ($indexval eq $oldindexval){
     $ifindex->cut;
     print "found one  \n";
    }
  }
 }
[download]

I deleted a whole ifIndex section from one of the files, but still end up with an "empty" result. Thanks in advance for any help.