Advanced Queuing - Oracle

no_message EXCEPTION;
pragma EXCEPTION_INIT(no_message, -25254);
order_msg boladm.order_typ;
new_status VARCHAR2(30);
monitor BOOLEAN := TRUE;
begin_time NUMBER;
end_time NUMBER;
BEGIN
begin_time := dbms_utility.get_time;
WHILE (monitor)
LOOP
BEGIN
Dequeue Features
/* Construct the waiters list: */
agent_list(1) := aq$_agent('BILLED_ORDER', 'CS_billedorders_que', NULL);
agent_list(2) := aq$_agent('SHIPPED_ORDER', 'CS_shippedorders_que',
NULL);
agent_list(3) := aq$_agent('BACK_ORDER', 'CS_backorders_que', NULL);
agent_list(4) := aq$_agent('Booked_ORDER', 'CS_bookedorders_que', NULL);
/* Wait for order status messages: */
dbms_aq.listen(agent_list, wait_time, agent_w_message);
dbms_output.put_line('Agent' || agent_w_message.name || ' Address '||
agent_w_message.address);
/* Dequeue the message from the queue: */
dequeue_message(agent_w_message.address, agent_w_message.name, order_msg);
/* Update the status of the order depending on the type of the message,
* the name of the agent contains the new state: */
update_status(agent_w_message.name, order_msg);
/* Exit if we have been working long enough: */
end_time := dbms_utility.get_time;
IF (end_time - begin_time > time) THEN
EXIT;
END IF;
EXCEPTION
WHEN no_message THEN
dbms_output.put_line('No messages in the past 2 minutes');
end_time := dbms_utility.get_time;
/* Exit if we have done enough work: */
IF (end_time - begin_time > time) THEN
A Sample Application Using AQ 8-93