Totally ordered Multicasting Algorithm using Lamport's Update message is time stamped with sender's logical time Update message is multicast (including sender itself) When a message is received It is put into local queue ordered according to timestamp, Multicast acknowledgments
Why acknowledgments are needed?
Acknowledgments are needed for each message when using Lamport's logical clocks to derive a total order of events in distributed systems as they ensure that messages are processed in the same order at each replica of the resource. The ordering of the acknowledgments according to the following
Pi sends an acknowledgment to Pj if Pi has not made an update request Pi's identifier is greater than Pj's identifier Pi's update has been processed;
And
Delivering the message to applications only when it is at the head of the queue and has been acknowledged by all involved processes ensures that updates are processed in the same order at all the servers.