What queue service interval events are

The following are types of queue service interval events:

  1. Queue Service Interval OK event indicates that after one of the following: a get operation was performed within a user-defined time period, known as the service interval.

    The Queue Service Interval OK event message can only be caused by a get operation.

    Note:
    In this section, Queue Service Interval OK events are referred to as OK events.
  2. Queue Service Interval High event indicates that after one of the following: a get operation was not performed within a user-defined service interval.

    The Queue Service Interval High event message can be caused by a get operation or an MQPUT call.

    Note:
    In this section, Queue Service Interval High events are referred to as high events.

To enable both Queue Service Interval OK and Queue Service Interval High events you need to set the QServiceIntervalEvent control attribute to High. Queue Service Interval OK events are automatically enabled when a Queue Service Interval High event is generated. You do not need to enable Queue Service Interval OK events independently.

These events are mutually exclusive, which means that if one is enabled the other is disabled. However, both events can be simultaneously disabled.

Figure 3 shows a graph of queue depth against time. At P1, an application issues an MQPUT, to put a message on the queue. At G1, another application issues an MQGET to remove the message from the queue.

Figure 3. Understanding queue service interval events
 Illustration showing a graph of queue depth against time for a single put and get operation. Firstly the put command is invoked at time = P1, followed by the get command at time = G1. The following text details the situations that will cause a Queue Service Interval OK event or a Queue Service Interval High event.

In terms of queue service interval events, these are the possible outcomes:

The actual algorithm for starting the service timer and generating events is described in Queue service interval events algorithm.