JMS previous message acknowledgement

Question

I am trying to solve the following case:

I am consuming messages, but take an outage in a system I am depending on for proper message processing (say a Database for example)

I am using CLIENT_ACKNOWLEDGE, and only calling the .acknowledge() method when no exception is thrown.

This works fine when I throw an exception, messages are not acknowledged, and I can see the unacknowledged queue building up. However, these messages have all already been delivered to the consumer.

Suppose now the Database comes back online, and any new message is processed successfully. So I call .acknowledge on them. I read that calling .acknowledge() acknowledges not only that message, but also all previously received messages in the consumer.

This is not what I want! I need these previously unacknowledged messages to be redelivered / retried. I would like to keep them on the queue and let JMS handle the retry, since maintaining a Collection in the consumer of "messages to be retried" might put at risk losing those messages ( since .acknowledge already ack'ed all of them + say the hardware failed).

Is there a way to explicitly acknowledge specific messages and not have this "acknowledge all prior messages" behavior?

Answer 1

Acknowledging specific message is not defined by JMS specification. Hence some JMS implementers provide per messaging acknowledging and some don't. You will need to check your JMS provider documentation.

Message queues generally will have an option on how the messages are delivered to a client, either First in first out (FIFO) or Priority based. Choose FIFO option so that all messages are delivered in the same order they came into a queue. When database goes offline and comes back, call recover method to redeliver all messages in the same order again.

Answer 2

You need to call recover on your session after the failure to restart message delivery from the first unacked message. From the JMS 1.1 spec section 4.4.11

When CLIENT_ACKNOWLEDGE mode is used, a client may build up a large number of unacknowledged messages while attempting to process them. A JMS provider should provide administrators with a way to limit client over-run so that clients are not driven to resource exhaustion and ensuing failure when some resource they are using is temporarily blocked.

A session’s recover method is used to stop a session and restart it with its first unacknowledged message. In effect, the session’s series of delivered messages is reset to the point after its last acknowledged message. The messages it now delivers may be different from those that were originally delivered due to message expiration and the arrival of higher-priority messages.