JMS AUTO_ACKNOWLEDGE when is it acknowledged?
java, jms, messaging
Solution
Please check this one (Wayback Machine link used as article went offline since 2020)
With `AUTO_ACKNOWLEDGE` mode the acknowledgment is always the last thing to happen implicitly after the `onMessage()` handler returns. The client receiving the messages can get finer-grained control over the delivery of guaranteed messages by specifying the `CLIENT_ACKNOWLEDGE` mode on the consuming session.
The use of `CLIENT_ACKNOWLEDGE` allows the application to control when the acknowledgment is sent. For example, an application can acknowledge a message - thereby relieving the JMS provider of its duty - and perform further processing of the data represented by the message. The key to this is the acknowledge() method on the Message object, as shown in Listing 1.
The `acknowledge()` method informs the JMS provider that the message has been successfully received by the consumer. This method throws an exception to the client if a provider failure occurs during the acknowledgment process. The provider failure results in the message being retained by the JMS server for redelivery.
Problem
I have tried to google this, but have not been successful. If I am using `AUTO_ACKNOWLEDGE`, and I have a consumer client written in Java, when is the message acknowledged? I am using a `MessageListener` which contains an `onMessage` method. Is the acknowledgement sent back to the server before `onMessage` or after `onMessage` completes or at some other point? Thanks in advance for any help anyone is able to provide!