ActionTokenReceivedEventHandler

Delegate

Visual Basic

Public Delegate Sub ActionTokenReceivedEventHandler (
    ByVal ftGroupMember As Object,
    ByVal actionTokenReceivedEventArgs
            As ActionTokenReceivedEventArgs )

C#

public delegate void ActionTokenReceivedEventHandler (
    object ftGroupMember,
    ActionTokenReceivedEventArgs actionTokenReceivedEventArgs );

Purpose

Process action token events for a fault tolerance group member.

Parameter	Description
ftGroupMember	This parameter receives the group member object.
actionTokenReceivedEventArgs	This parameter receives the closure and the action token.

Implementation

Each member program of a fault tolerance group must implement this method. Programs register a member callback delegate with each call to FTGroupMember.

Rendezvous fault tolerance software queues a member action event in three situations. In each case, it passes a different action argument, instructing the callback method to activate, deactivate, or prepare to activate the program.

•

When the number of active members drops below the active goal, the fault tolerance callback method (in the ranking inactive member process) receives the token ActionToken.Activate; the callback method must respond by assuming the duties of an active member.

•

When the number of active members exceeds the active goal, the fault tolerance callback method (in any active member that is outranked by another active member) receives the action token ActionToken.Deactivate; the callback method must respond by switching the program to its inactive state.

•

When the number of active members equals the active goal, and Rendezvous fault tolerance software detects that it might soon decrease below the active goal, the fault tolerance callback method (in the ranking inactive member) receives the action token ActionToken.PrepareToActivate; the callback method must respond by making the program ready to activate immediately. For example, preparatory steps might include time-consuming tasks such as connecting to a database. If the callback method subsequently receives the ActionToken.Activate token, it will be ready to activate without delay.

For additional information see Fault Tolerance Callback Actions in TIBCO Rendezvous Concepts.

See Also

FTGroupMember

ActionTokenReceivedEventArgs