The responsibility of guaranteed delivery lies with the sender of the message. Only messages sent persistently will be stored until delivered by the messaging system. This guarantees that the message will not be lost due to a crash or shutdown of the messaging system. This is referred to as once-and-only-once delivery.
If set to LOCAL, then the JMS session for the adapter is transacted. The session is always committed after the message is processed, regardless of any errors encountered during the processing stages. This ensures that the message is processed only once.
If set to AUTO, then the session is not transacted, but the message is automatically acknowledged immediately according to the JMS definition of AUTO_ACK.
If set to DUPS_OK, then the session is not transacted, but the message is automatically acknowledged immediately according to the JMS definition of DUPS_OK_ACK.
If set to CLIENT, then the session is not transacted, and the message is not acknowledged by the adapter. Instead, it is expected that a lifecycle listener specified by the Message LifeCycle Listener field acknowledges the message as needed. The lifecycle listener is called with an AWAITING_CLIENT_ACK lifecycle event at the typical point that an acknowledgement is expected. It is rare that this mode is needed.