XMSC_WMQ_READ_AHEAD_CLOSE_POLICY

    Data type:
    System.Int32

    Property of:
    Destination

This property determines, for messages being delivered to an asynchronous message listener, what happens to messages in the internal read ahead buffer when the message consumer is closed.

This property is applicable in specifying closing queue options when consuming messages from a destination and not applicable when sending messages to a destination.

This property is ignored for queue browsers since during browse the messages are still available in the queues.

The valid values for this property are:

    XMSC_WMQ_READ_AHEAD_CLOSE_POLICY_DELIVER_CURRENT
    Only the current message listener invocation completes before returning, potentially leaving messages in the internal read ahead buffer, which are then discarded.

    XMSC_WMQ_READ_AHEAD_CLOSE_POLICY_DELIVER_ALL
    All messages in the internal read ahead buffer are delivered to the application message listener before returning.

By default this property is set to XMSC_WMQ _READ_AHEAD_CLOSE_POLICY_DELIVER_CURRENT.

Note:

    Abnormal application termination
    All the messages in the read ahead buffer are lost when an XMS application terminates abruptly.

    Implications for transactions
    The read ahead is disabled when the applications use transactions. So, the application is not seeing any difference in the behavior when they use transacted sessions.

    Implications of session scknowledgement modes
    The read ahead is enabled on a non-transacted session when the acknowledgment modes are either XMSC_AUTO_ACKNOWLEDGE or XMSC_DUPS_OK_ACKNOWLEDGE. The read ahead is disabled if the session acknowledgment mode is XMSC_CLIENT_ACKNOWLEDGE irrespective of transacted or non-transacted sessions.

    Implications for queue browsers and queue browser selectors
    The queue browsers and queue browser selectors, used in XMS applications, get the performance advantage from read ahead. Closing the queue browser does not degrade performance because the message is still available in the queue for ay further operations. There are no other implications for queue browsers and queue browser selectors apart from performance benefits of read ahead.

Parent topic: Property definitions