When using message queues in WSO2 Message Broker, messages are removed from message store when the message consumers acknowledge for the messages received. There are several Acknowledgement Models defined in JMS specification 1.1. If the client did not acknowledge for a sent message, broker assumes that message is not received by the message consumer and try to re-deliver the message.
Thus, for the broker to assume that message has been not received by the JMS consumer application it uses "Ack Time-out". For WSO2 Message Broker you can configure this value editing qpid-config.xml file.
Navigate to <MB_HOME>/repository/conf/advanced/ folder and edit following entry.
<waitTimes>
<!-- Max wait time(in seconds) for a acknowledgement for a given message from the client -->
<maxAckWaitTime>10</maxAckWaitTime>
There may be a practical scenario where we use "CLIENT_ACKNOWLEDGE" mode or JMS transactions where the client application does not acknowledge the message if some operation on the message fails. If a particular message is being failed at the client side again and again, there should be a way to remove that message from the system after a defined number of message re-deliveries has breached. This is an added functionality to WSO2 Message Broker. To configure this edit following entry in qpid-config.xml file:
<!--Broker will drop the message after the configured number of delivery attempts for each message.--> <maximumNumberOfMessageDeliveryAttempts>10</maximumNumberOfMessageDeliveryAttempts>
Note that this is the number of delivery attempt not re-delivery attempts.