Heartbeat

Many applications are required to support processing that is triggered at regular intervals or according to a schedule. Some examples are:
  • Detection of inactivity. For example, a request was sent, but the response was not received within the expected time frame.
  • Transmissions being sent on a set schedule.
  • Quality of service checks
In FTM, such requirements can be supported through the use of a heartbeat flow. A sample heartbeat flow is supplied with FTM, and is used in the FTM sample application to demonstrate how this type of function can be delivered.

The heartbeat flow generates heartbeat events on a specified time interval, which is 60 seconds by default. The context data added to the events by the flow contains the current time (in UTC or in the time zone that the IBM® App Connect Enterprise is operating in. For more information, see Time zone considerations). These events can be used to trigger actions based on a specific date or time, or can be used to determine if an object has timed out.

There are two types of heartbeat event, the start event (E_HeartbeatStart), which is generated the first time the flow is started, and all subsequent heartbeat events (E_Heartbeat). The start event can be used for recovery actions after a restart of the integration node or for initialization tasks.

Examples of using the heartbeat include:
  • The opening and closing of service participants and their associated channels.
  • Timing out of objects. The object table contains a timeout field, which can be populated as an option.
  • The start event can be used to initialize the caches that store the static data and load them into the shared memory of the execution groups.

The events generated by the heartbeat flow can be included in an FSM model to cause transitions and corresponding action processing when these events are processed.