A fault tolerance group is a set of program processes that cooperate for fault-tolerant service. Each
member of a fault tolerance group is an event object instance, in a process running on a computer attached to a network; by extension, we also say that the process is a
member of the fault tolerance group. A fault tolerance group can have any number of members.
New processes can join the group (become members) at any time by creating a fault tolerance member object. Each process that joins a group remains a member until it either withdraws or terminates. Member processes can
withdraw from the group (cease to be members) at any time by destroying their fault tolerance member object.
