What is the "delivery mode" in AMQP?
I understand that 2 options are available:
- "Non-persistent"
- "Persistent"
But what does this actually mean?
"Non-persistent" as in : the AMQP fabric will try to deliver the message if there are no consumers, the message will be dropped?
"Persistent" as in : AMQP will retry the message until a consumer accepts it??
Solution 1:
Messages marked as 'persistent' that are delivered to 'durable' queues will be logged to disk. Durable queues are recovered in the event of a crash, along with any persistent messages they stored prior to the crash.
Solution 2:
delivery_mode in AMQP determines if message will be stored on disk after broker restarts. You can mark messages as persistent - by seting delivery_mode property = 2 when you publish message
for instance in PHP (PECL AMQP extension):
$exchange->publish($text, $routingKey, null, array('delivery_mode' => 2));
You would also need to declare queue as durable (or it will be dropped after broker stops)
$queue->setFlags(AMQP_DURABLE);