Timer service

FTM SWIFT has a timer service that allows you to store information needed at a defined time and to provide a wake-up message for timeout situations. Such situations occur when a requestor submits an action and expects a response within a specified time limit. However, this response is not detected within that time. The timer service searches for these timeout situations using a polling interval. When the timer service detects a timeout situation, it sends a timer wake-up message to the affected service.

The timer service consists of a timer interface and the timer wake-up processor.
Timer interface
Any FTM SWIFT component or application that requires the timer service must pass a request to the timer interface. The timer interface has nodes that can set and cancel a timer. The node to set a timer inserts a timer record into the timer database and the node to cancel a timer deletes it. For additional information about these nodes, see DniSetTimer node and DniCancelTimer node.
Timer wake-up processor
The timer wake-up processor is an independently executing message flow. It starts when an FTM SWIFT instance server starts. Once started, it continuously polls the timer database for expired timers. A wake-up message is sent to the appropriate destination for all expired timers. The associated timer records are then deleted.

Figure 1 shows how the timer service is integrated into FTM SWIFT.

Figure 1. The timer service in FTM SWIFT
The timer service in FTM SWIFT

Service interface queue name

Not applicable.

Prerequisites

None.

Properties

Node property Mandatory
Customization
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 Description
PollingInterval Yes None The timer interval that the timer message flow watches for expired timer entries and sends appropriate wake-up messages. The default is 60 seconds.
Category Yes None A CO of type DniTimer. A category summarizes one timer environment that consists of one timer wake-up processor and one timer table. The default is DNIT0060.
Service Name Yes None The name of the service. This name is included in events issued by this node, and can be used to identify events associated with a particular service. The default is DNI_TIMER.

Process

The timer wake-up processor:
  • Polls its timer database table periodically for expired timer entries that the Set Timer requests set.

    You can configure different polling frequency categories for FTM SWIFT. You can specify one of them with the Set Timer request to determine the timer accuracy. See the Category property in the request of the DniSetTimer node. The category defines the table that the timer wake-up processor uses. For how the categories are configured, see Timer service.

  • If it finds an expired timer record, it:
    • Retrieves the required information from the table entry and creates a wake-up message.
    • Determines the service interface queue (instance.ou.service) of the client application or service to which the wake-up message is to be sent.
      instance
      The instance that hosts the timer wake-up processor.
      ou
      The OU for which the timer was set (that is, the value set for OU field of the ComIbmDni folder in the Timer Set request).
      service
      The service for which the timer was set (that is, the value set for TargetService field of the ComIbmDni folder in the Timer Set request).
    • Sends the wake-up message to the identified client application or service, and deletes the timer record from the database table. The wake-up message is a datagram with the MsgType field of the MQMD set to MQMT_DATAGRAM. The message does not contain a message body.

Error conditions

If a processing error occurs, the timer wake-up processor does not remove the timer record from the timer database table, stores an event in the event database table, and publishes the event to registered subscribers.

If one of the following errors occurs, the timer wake-up processor writes an error message to the system log and stops processing:
  • A mandatory property is not set
  • The PollingInterval property is set to an invalid value