第20章 Configuring Pre-Acknowledgments

JMS specifies three acknowledgement modes:

In some cases you can afford to lose messages in the event of a failure, so it would make sense to acknowledge the message on the server before delivering it to the client. This extra mode is supported by JBoss EAP messaging and is called pre-acknowledge mode.

The disadvantage of pre-acknowledging on the server before delivery is that the message will be lost if the server’s system crashes after acknowledging the message but before it is delivered to the client. In that case, the message is lost and will not be recovered when the system restarts.

Depending on your messaging case, pre-acknowledge mode can avoid extra network traffic and CPU usage at the cost of coping with message loss.

An example use case for pre-acknowledgement is for stock price update messages. With these messages, it might be reasonable to lose a message in event of a crash since the next price update message will arrive soon, overriding the previous price.

/subsystem=messaging-activemq/server=default/connection-factory=RemoteConnectionFactory:write-attribute(name=pre-acknowledge,value=true)

java.naming.factory.initial=org.apache.activemq.artemis.jndi.ActiveMQInitialContextFactory
connection.ConnectionFactory=tcp://localhost:8080?preAcknowledge=true

// messages will be acknowledge on the server *before* being delivered to the client
Session session = connection.createSession(false, ActiveMQJMSConstants.PRE_ACKNOWLEDGE);