In a multi-user game, players at separate workstations move
figures around a common scene. The figures may throw
projectiles at one another, and a hit debilitates the
unfortunate recipient for some pre-determined interval. What
type of ordering is required here.
The game incorporates magic devices which may be picked up
by a player to assist her. What type of ordering should be
applied to the pick up device operation?
Three processes, 0, 1, and 2, use the ISIS total ordering
protocol, as described in the notes using sequence number
agreements. A message is sent from process 0, which reaches
process 1 ok, but is delayed in reaching process 2. Process 1
then sends a message which reaches process 2 ok. The original
message from process 0 then reaches process 2. In which order
are the messages delivered to the processes?
A process group using CBcast has three members, 0,1,2.
Process 0 sends two messages with vector timestamps (6,9,10) and
(7,10,11). Process 1 sends two messages with vector timestamps
(5,9,10) and (5,10,10). Process 3 sends two messages with
vector timestamps (6,9,11) and (6,9,12). Show a possible
ordering of the transmission and delivery events at these
processes.
What guarantees on message delivery are required for CBcast?
