POE::Session-create(
  inline_states => {
    _start  => \&task_start,
    subscribe => \&subscribe,
    inmessage => \&inmessage,
    # some other events ...
  },
);

my $pq = POE::QUEUE::Array->new();
$poe_kernel->run();
exit;

sub task_start {
  my ($kernel, $heap) = @_[KERNEL, HEAP];
  $kernel->yield('xmlmsg_open');
}

sub xmlmsg_open
{
  my ($kernel, $session) = @_[KERNEL, SESSION];
  # Code for a Vendor based XML message connect
  # Includes a call to a seperate function that opens the subscription_check
}

sub subscribe
{
  my ($kernel, $heap, $session, $prearg, $postargs) = @_[KERNEL, HEAP...etc];
   $kernel->post(
        $alias => 'subscribe',
        InXMLMessageCallBack => $session->postback('inmessage' $alias),
        # Other postbacks
   );
}

sub inmessage
{
 my ($kernel, $session, $heap, $preargs, $postargs) = @_[KERNEL, SESSION, HEAP...];
  $msg = $postargs->[0];

  # code that reads something called getBody from the XML and determines the priority of the message.

  $pq->enqueue( $priority, $msg->getBody);
  return 1;
}