Advanced Queuing - Oracle

JMS Propagation
When a schedule is created, a job is automatically submitted to the job_queue
facility to handle propagation.
The administrative calls for propagation scheduling provide great flexibility for
managing the schedules (see "Scheduling a Queue Propagation", Chapter 9,
"Administrative Interface"). The duration or propagation window parameter of a
schedule specifies the time frame during which propagation has to take place. If the
duration is unspecified then the time frame is an infinite single window. If a
window has to be repeated periodically then a finite duration is specified along
with a next_time function that defines the periodic interval between successive
windows.
The latency parameter for a schedule is relevant only when a queue does not have
any messages to be propagated. This parameter specifies the time interval within
which a queue has to be rechecked for messages. Note that if the latency parameter
is to be enforced, then the job_queue_interval parameter for the job_queue_
processes should be less than or equal to the latency parameter. The propagation
schedules defined for a queue can be changed or dropped at anytime during the life
of the queue. In addition there are calls for temporarily disabling a schedule
(instead of dropping the schedule) and enabling a disabled schedule. A schedule is
active when messages are being propagated in that schedule. All the administrative
calls can be made irrespective of whether the schedule is active or not. If a schedule
is active then it will take a few seconds for the calls to be executed.
Job queue processes must be started for propagation to take place. At least 2 job
queue processes must be started. The dblinks to the destination database must also
be valid. The source and destination topics of the propagation must be of the same
message type. The remote topic must be enabled for enqueue. The user of the
dblink must also have enqueue privileges to the remote topic.
Example Code
public void schedule_propagation(TopicSession jms_session)
{
Topic topic;
try
{
/* get a handle to the OE_bookedorders_topic */
topic = ((AQjmsSession)jms_session).getTopic("WS",
"WS_bookedorders_topic");
/* Schedule propagation immediately with duration of 5 minutes and latency
20 sec */
Creating Applications Using JMS 12-89