# ...
my $twig = XML::Twig->new();
while (<$fh>) {
    chomp;
    my $msg = {};
    $twig->parse($_);
    for my $child ($twig->root->children) {
        my $handler = $child->tag;
        if ($dispatch{$handler}) {
            $dispatch{$handler}->($child, $msg);
        }
        else {
            die "Haven't written handler for '$handler' yet";
        }
    }
    # do something with $msg
}