ActiveMQ from version 5.4 has an optional persistent scheduler built into the ActiveMQ message broker. It is enabled by setting the broker schedulerSupport attribute to true in the Xml Configuration.
An ActiveMQ client can take advantage of a delayed delivery by using the following message properties:
Check your Message Properties
The message property
scheduledJobId is reserved for use by the Job Scheduler. If this property is set before sending, the message will be sent immediately and not scheduled. Also, after a scheduled message is received, the property
scheduledJobId will be set on the received message so keep this in mind if using something like a Camel Route which might automatically copy properties over when re-sending a message.
|AMQ_SCHEDULED_DELAY||long||The time in milliseconds that a message will wait before being scheduled to be delivered by the broker|
|AMQ_SCHEDULED_PERIOD||long||The time in milliseconds to wait after the start time to wait before scheduling the message again|
|AMQ_SCHEDULED_REPEAT||int||The number of times to repeat scheduling a message for delivery|
|AMQ_SCHEDULED_CRON||String||Use a Cron entry to set the schedule|
For the connivence of Java JMS clients – there’s an interface with the property names used for scheduling atorg.apache.activemq.ScheduledMessage.
For example, to have a message scheduled for delivery in 60 seconds – you would need to set the AMQ_SCHEDULED_DELAYproperty:
You can set a message to wait with an initial delay, and the repeat delivery 10 times, waiting 10 seconds between each re-delivery:
You can also use CRON to schedule a message, for example, if you want a message scheduled to be delivered every hour, you would need to set the CRON entry to be – 0 * * * * – e.g.
CRON scheduling takes priority over using message delay – however, if a repeat and period is set with a CRON entry, the ActiveMQ scheduler will schedule delivery of the message for every time the CRON entry fires. Easier to explain with an example. Supposing that you want a message to be delivered 10 times, with a one second delay between each message – and you wanted this to happen every hour – you’d do this: