Sun Java System Message Queue 4.2 Developer's Guide for Java Clients

Acknowledgment Modes

A session’s acknowledgment mode determines the way your application handles the exchange of acknowledgment information when receiving messages from a broker. The JMS specification defines three possible acknowledgment modes:

The standard JMS Session interface, defined in package javax.jms, defines static constants for the first three acknowledgment modes (AUTO_ACKNOWLEDGE, CLIENT_ACKNOWLEDGE, and DUPS_OK_ACKNOWLEDGE), to be used as arguments to the connection’s createSession method. The constant representing the fourth mode (NO_ACKNOWLEDGE) is defined in the extended Message Queue version of the interface, in package com.sun.messaging.jms. The session method getAcknowledgeMode returns one of these constants:

int  ackMode = mySession.getAcknowledgeMode();
switch (ackMode)
    case Session.AUTO_ACKNOWLEDGE:
      /* Code here to handle auto-acknowledge mode */
    case Session.CLIENT_ACKNOWLEDGE:
      /* Code here to handle client-acknowledge mode */
    case Session.DUPS_OK_ACKNOWLEDGE:
      /* Code here to handle dups-OK-acknowledge mode */
    case com.sun.messaging.jms.Session.NO_ACKNOWLEDGE:
      /* Code here to handle no-acknowledge mode */

Note –

All of the acknowledgment modes discussed above apply to message consumption. For message production, the broker’s acknowledgment behavior depends on the message’s delivery mode (persistent or nonpersistent; see Message Header). The broker acknowledges the receipt of persistent messages, but not of nonpersistent ones; this behavior is not configurable by the client.

In a transacted session (see next section), the acknowledgment mode is ignored and all acknowledgment processing is handled for you automatically by the Message Queue client runtime. In this case, the getAcknowledgeMode method returns the special constant Session.SESSION_TRANSACTED.