Messages can be set with an optional time to live when sending them.
HornetQ will not deliver a message to a consumer after it's time to live has been exceeded. If the message hasn't been delivered by the time that time to live is reached the server can discard it.
HornetQ's addresses can be assigned a expiry address so that, when messages are expired, they are removed from the queue and sent to the expiry address. Many different queues can be bound to an expiry address. These expired messages can later be consumed for further inspection.
Using HornetQ Core API, you can set an expiration time directly on the message:
// message will expire in 5000ms from now message.setExpiration(System.currentTimeMillis() + 5000);
JMS MessageProducer allows to set a TimeToLive for the messages it sent:
// messages sent by this producer will be retained for 5s (5000ms) before expiration producer.setTimeToLive(5000);
Expired messages which are consumed from an expiry address have the following properties:
a String property containing the original address of the expired message
a Long property containing the actual expiration time of the expired message
Expiry address are defined in the address-setting configuration:
<!-- expired messages in exampleQueue will be sent to the expiry address expiryQueue --> <address-setting match="jms.queue.exampleQueue"> <expiry-address>jms.queue.expiryQueue</expiry-address> </address-setting>
If messages are expired and no expiry address is specified, messages are simply removed from the queue and dropped. Address wildcards can be used to configure expiry address for a set of addresses (see Chapter 13, Understanding the HornetQ Wildcard Syntax).
A reaper thread will periodically inspect the queues to check if messages have expired.
The reaper thread can be configured with the following properties in hornetq-configuration.xml
How often the queues will be scanned to detect expired messages (in milliseconds, default is 30000ms, set to -1 to disable the reaper thread)
The reaper thread priority (it must be between 0 and 9, 9 being the highest priority, default is 3)
See Section 11.1.28, “Message Expiration” for an example which shows how message expiry is configured and used with JMS.