Coded Example

In this example of a group user routine, the routine has two functions to perform:

Maintain a table containing the member names and member tokens of members in the group. When a member becomes active, the group user routine adds the member to the table.
Initiate® a takeover if the primary member in the group fails. This routine runs in a group where one member is the primary member and another member is the backup member.

To accomplish these functions, the group user routine is concerned with two types of events:

Member state changes (GEPLTYPE=GEMSTATE).
Member status update missing. To test for this event, the routine uses a test-under-mask operation, with a mask of X'30'. This covers the following conditions:
- GEPLFLG2 = X'20', indicating that the GEPLMISR bit is on (the member's status user routine reported a status update missing for the member)
- GEPLFLG2 = X'10', indicating that the GEPLMISD bit is on (XCF assumed a status update missing for the member).

The group user routine also has to be concerned with skipping of events. The logic of the routine covers the possibility that either a status update missing or a member state change event might have been skipped.

The following describes the group user routine logic (see Figure 1,Figure 2, and Figure 3 for a summary).

The routine first checks to see if the event is member-related. If not, the routine takes no action.
If the event is member-related, the routine then checks to see if one of the status update missing flags (GEPLMISR or GEPLMISD) is on.