Working With System Image Definitions › Define a Resource to a System Image › Define the Display and Heartbeat Details

Define the Display and Heartbeat Details

Some resource classes let you specify how to find out about the status of the resource. Before the region starts or stops a resource, the region executes the display method to determine the actual state of the resource. The heartbeat interval enables you to set up regular checking of the resource status.

To define the display and heartbeat details for the resource

1. Press F8 (Forward) from the Force Inactivation Details panel.

   The Display and Heartbeat Details panel appears. For an example, see a template distributed with the product.

   Generally, the CHECKALL, CHK (check), and D (display) commands use the method on this panel when checking or displaying the resource status. The exceptions are resources that have their own special D commands. You can identify these exceptions from the list of command definitions. To access the list, enter the /ASADMIN.C path.

2. Specify the display method required for status checking. You can specify a system command or a process without specifying the heartbeat interval.

   Note: Resource definitions with a class of JOB or STC have a default display method that is used when no specific method is specified. The default method checks the existence of the address space ID, and sets the actual state to either ACTIVE or INACTIVE. When a JOB or STC definition specifies no display method, the D command issues D J,resource_name.

   Important! The heartbeat feature increases CPU consumption. Use this feature only for resources that are liable to change state without an accompanying message.

   • If the display method is simple, specify a system command, heartbeat interval, and the expected response message.

     You can extend the message definition.

   • If the display method is complex, use a process.

     Note: You can use the $NCL process to execute an NCL procedure.

     If you use a process, your process must set the return code to one of the following values:

     • 0 notifies the region to set the actual state to ACTIVE.
     • 1 notifies the region to set the actual state to STARTING.
     • 2 notifies the region to set the actual state to STOPPING.
     • 3 notifies the region to set the actual state to DEGRADED.
     • 5 notifies the region to set the actual state to INACTIVE.
     • 6 notifies the region to set the actual state to FAILED.
     • 12 notifies the region to do nothing. For example, the process has set the state already by using the SETSTATE macro.
     • Other return codes notify the region to set the actual state to UNKNOWN.