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:

   • An MQPUT call

   • A get operation that leaves a non-empty queue

   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:

   • An MQPUT call

   • A get operation that leaves a non-empty queue

   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 we 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

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

• If the elapsed time between the put and get is less than or equal to the service interval:

  • A Queue Service Interval OK event is generated at G1, if queue service interval events are enabled

• If the elapsed time between the put and get is greater than the service interval:

  • A Queue Service Interval High event is generated at G1, if queue service interval events are enabled.

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