print "<SESSION>\n";
print_hash(\%hash);
print "</SESSION>\n";

sub print_hash {
	my $hashref = shift;
	my $prefix = (@_ ? shift : '') . '  ';

	foreach my $key (sort keys %$hashref) {
		print "$prefix<$key>\n";
		if (ref $hashref->{$key}) {
			print_hash($hashref->{$key}, $prefix);
		} else {
			print "$prefix  $hashref->{$key}\n"
		}
		print "$prefix</$key>\n";
	}
}

##</code><code>##

use XML::Simple;
use strict;
...

print XMLout(\%hash, RootName => 'SESSION');