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