Group Services Programming Guide and Reference

GSAPI summary

The GSAPI contains these types of routines:

• Routines to issue commands that request an action from the Group Services subsystem
• Routines that define callback routines that handle notifications from the Group Services subsystem.
• Deactivate scripts that the Group Services subsystem runs against providers that are targeted for expulsion from a group.

Group Services supports both the 32-bit and the 64-bit operating environments.

GSAPI commands

The following GSAPI subroutines request an action from the Group Services subsystem:

Subroutine

Action

ha_gs_change_state_value

Propose a change to the group's state value.

ha_gs_change_attributes

Dynamically change certain group attributes.

ha_gs_dispatch

Check for notifications.

ha_gs_expel

Expel one or more providers from the group.

ha_gs_get_adapter_info

Get the node number and the adapter interface name corresponding to a given IP address.

ha_gs_get_ffdc_id

Obtain an FFDC ID to find the cause when the hags daemon stops suddenly and unexpectedly.

ha_gs_get_node_number

Get the local node number.

ha_gs_goodbye

Leave a group immediately.

ha_gs_init

Register with Group Services.

ha_gs_join

Join a group as a provider.

ha_gs_leave

Leave a group (as a provider).

ha_gs_quit

Terminate the connection to the Group Services subsystem.

ha_gs_send_message

Send data to all of the providers in the group.

ha_gs_subscribe

Subscribe to a group.

ha_gs_unsubscribe

Unregister as a subscriber to a group.

ha_gs_vote

Vote on a proposed change to a group's membership, state value, attribute, and so forth, by approving, rejecting, or continuing.

GSAPI routines for handling notifications

The following GSAPI subroutines define callback routines to handle notifications from the Group Services subsystem that something is happening:

Subroutine

Response

ha_gs_announcement_callback

Respond to an announcement that:

• One or more providers failed a responsiveness check.
• One or more providers that previously failed responsiveness checks are now responding successfully.
• The Group Services daemon has died or is about to die.
• The voting time limit has expired.

ha_gs_delayed_error_callback

Handle an asynchronously presented error.

ha_gs_n_phase_callback

Respond to a request for a vote on a proposed join, leave, expel, cast-out, failure leave, change attribute, or group state change request.

ha_gs_protocol_approved_callback

Respond to a notification that a proposal has been approved.

ha_gs_protocol_rejected_callback

Respond to a notification that a proposal has been rejected.

ha_gs_responsiveness_callback

Respond to a responsiveness check.

ha_gs_subscriber_callback

Receive a notification that a subscribed-to group's membership or state has been changed.

GSAPI deactivate scripts

For the specifications of deactivate scripts to use with expel protocols and with deactivate-on-failure handling, see and Deactivate-on-failure handling.

GSAPI First Failure Data Capture subroutine

The ha_gs_get_ffdc_id GSAPI subroutine retrieves a related First Failure Data Capture (FFDC) ID from the Group Services subsystem, provided it is available, when the Group Services daemon fails. See .