CATOCS and RAB

Simple Implementation of RAB

RAB is not ORDERED

ABCAST -- A Reliable Ordered Atomic Broadcast

ABCAST (Skeen vs. Birman)

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An Example

Virtual Synchrony

Three kinds of primitives

Need to reach agreement on who is in a group.

Suppose you didn’t like this stuff

A Complaint

Limitations

Unrecognized Causality(can’t say “for sure”

Fire Fire Fire

Imposing Order

Lack of serialization(can’t say “together”)

Unexpressed Semantics(can’t say the whole story)

Lack of efficiency of state-level techniques

Some Real Examples

Final Considerations

Bottom Line