The message user routine enables an active member of an XCF group to receive messages from other members of the group. Without a message user routine, a member cannot receive any messages.

The message user routine also can be used to provide a response to a message, when the member is capable of participating in a protocol that involves sending a response to a sender.

Code a message user routine when you have one or more members in a group that will be receiving messages from other members and possibly sending responses to those messages. You can use the same message user routine for different members.

The status user routine determines whether a member is operating normally. By identifying a status user routine, the member alerts XCF to begin monitoring a field that the member might be updating. If the member fails to update the field within a member-specified time interval, XCF schedules the status user routine to determine if a problem exists. (XCF schedules the status user routine only for active members.) If a problem does exist, XCF notifies other active members of the group through their group user routines.

Code a status user routine when you want XCF to monitor the status field of a member. You can use the same status user routine for different members.

The group user routine enables XCF to notify an active member of a group when there is a change in the operational state of any other member in the group, or a change to the status of any system in the sysplex. If a member does not have a group user routine, XCF cannot notify that member of changes that occur.

Code a group user routine when you want XCF to notify the member about changes to other members of the same group or about changes to systems in the sysplex. You can use the same group user routine for different members.

The message notify user routine enables XCF to notify a sender about the completion of a message. If the sender specified that a response to the message was required, the message notify user routine is used to process the collected responses. If the sender specified that a response was not required, XCF notifies the sender about the status of the message.

Your application can specify a message notify user routine when it joins a group, when it sends a message, or when it explicitly calls the user routine to process a response. This allows you to assign a different message notify user routine to different messages.

Code a message notify user routine if your application includes a protocol for sending messages that require a response or if your application wants to be notified when the message completes. You can use the same message notify user routine for different members.