use strict;
use warnings;
use feature qw( say );

use XML::LibXML               qw( );
use XML::LibXML::XPathContext qw( );

my $parser = XML::LibXML->new();
my $doc = $parser->parse_file($qfn);
my $xpc = XML::LibXML::XPathContext->new($doc);
$xpc->registerNs('xi', 'http://www.w3.org/2001/XInclude');

for ($xpc->findnodes('//xi:include/@href')) {
   say $_->getValue();
}

##</code><code>##

for ($xpc->findnodes('//xi:include')) {
   say $_->getAttribute('href');
}