Advanced Queuing - Oracle

Propagation
Scenario
Enhanced Propagation Scheduling Capabilities
Exception Handling During Propagation
Message Format Transformation During Propagation
Propagation Features
This feature allows applications to communicate with each other without being
connected to the same database or to the same queue. Messages can be propagated
from one queue to another. The destination queue can be located in the same
database or in a remote database. Propagation is performed by job queue
background processes. Propagation to the remote queue uses database links over
Oracle Net Services or HTTP(S).
The propagation feature is used as follows. First one or more subscribers are
defined for the queue from which messages are to be propagated (see
"Subscriptions and Recipient Lists" on page 8-36). Second, a schedule is defined for
each destination where messages are to be propagated from the queue. Enqueued
messages will be propagated and automatically available for dequeuing at the
destination queues.
For propagation over the Internet, you must specify the remote Internet user in the
database link. The remote Internet user must have privileges to enqueue in the
destination queue.
Note that two or more job_queue background processes must be running to use
propagation. This is in addition to the number of job_queue background
processes needed for handling non-propagation related jobs. Also, if you want to
deploy remote propagation, you must ensure that the database link specified for the
schedule is valid and have proper privileges for enqueuing into the destination
queue. For more information about the administrative commands for managing
propagation schedules, see "Propagation Scheduling" on page 8-108.
Propagation also has mechanisms for handling failure. For example, if the database
link specified is invalid, then the appropriate error message is reported.
Finally, propagation provides detailed statistics about the messages propagated and
the schedule itself. This information can be used to properly tune the schedules for
best performance. See "Enhanced Propagation Scheduling Capabilities" for a
discussion of the failure handling and error reporting facilities of propagation and
propagation statistics.
A Sample Application Using AQ 8-107