Advanced Queuing - Oracle

Enqueue Features
Message Properties]" on page 11-9 in Chapter 11, "Operational Interface: Basic
Operations"). The delay interval determines when an enqueued message is marked
as available to the dequeuers after the message is enqueued.
When a message is enqueued with a delay time set, the message is marked in a
WAIT state. Messages in WAIT state are masked from the default dequeue calls. A
background time-manager daemon wakes up periodically, scans an internal index
for all WAIT state messages, and marks messages as READY if their delay time has
passed. The time-manager will then post to all foreground processes that are
waiting on queues for messages that have just been made available.
Scenario
In the BooksOnLine application, delay can be used to implement deferred billing. A
billing application can define a queue where shipped orders that are not billed
immediately can be placed in a deferred billing queue with a delay. For example, a
certain class of customer accounts, such as those of corporate customers, may not be
billed for 15 days. The billing application dequeues incoming shipped order
messages (from the shippedorders queue) and if the order is for a corporate
customer, this order is enqueued into a deferred billing queue with a delay.
PL/SQL (DBMS_AQADM Package): Example Code
/* Enqueue an order to implement deferred billing so that the order is not made
visible again until delay has expired: */
CREATE OR REPLACE PROCEDURE defer_billing(deferred_billing_order order_typ)
AS
defer_bill_queue_name VARCHAR2(62);
enqopt dbms_aq.enqueue_options_t;
msgprop dbms_aq.message_properties_t;
enq_msgid RAW(16);
BEGIN
/* Enqueue the order into the deferred billing queue with a delay of 15 days: */
defer_bill_queue_name := 'CBADM.deferbilling_que';
msgprop.delay := 15*60*60*24;
dbms_aq.enqueue(defer_bill_queue_name, enqopt, msgprop,
deferred_billing_order, enq_msgid);
END;
/
Visual Basic (OO4O): Example Code
set oraaq = OraDatabase.CreateAQ("CBADM.deferbilling_que")
Set OraMsg = OraAq.AQMsg(ORATYPE_OBJECT, "BOLADM.order_typ")
8-46 Oracle9i Application Developer’s Guide - Advanced Queuing