Advanced Queuing - Oracle

General Features of JMS
Example Scenario and Code
The BooksOnLine application processes customer billings in its CB and CBADM
schemas. CB (Customer Billing) schema hosts the customer billing application, and
the CBADM schema hosts all related billing data stored as queue tables. To protect
the billing data, the billing application and the billing data reside in different
schemas. The billing application is allowed only to dequeue messages from CBADM_
shippedorders_topic, the shipped order topic. It processes the messages, and
then enqueues new messages into CBADM_billedorders_topic, the billed order
topic.
To protect the queues from other illegal operations from the application, the
following two grant calls are made:
/* Grant dequeue privilege on the shipped orders queue to the Customer
Billing application. The CB application retrieves orders that are shipped
but not billed from the shipped orders queue. */
((AQjmsDestination)cbadm_shippedorders_topic).grantTopicPrivilege(t_sess,
"DEQUEUE", "CB", false);
where t_sess is the session
/* Grant enqueue privilege on the billed orders queue to Customer Billing
application.The CB application is allowed to put billed orders into this
queue after processing the orders. */
((AQjmsDestination)cbadm_billedorders_topic).grantTopicPrivilege(t_sess,
"ENQUEUE", "CB", false);
Retention and Message History in JMS
AQ allows users retain messages in the queue table. This means that SQL can then
be used to query these message for analysis. Messages are often related to each
other. For example, if a message is produced as a result of the consumption of
another message, the two are related. As the application designer, you may want to
keep track of such relationships. Along with retention and message identifiers, AQ
lets you automatically create message journals, also called tracking journals or event
journals. Taken together -- retention, message identifiers and SQL queries -- make it
possible to build powerful message warehouses.
Example Scenario and Code
Let us suppose that the shipping application needs to determine the average
processing times of orders. This includes the time the order has to wait in the
12-18 Oracle9i Application Developer’s Guide - Advanced Queuing