NOTE
3.2 ZAB
An entry point to ZooKeeper Atomic Broadcast (ZAB), ZooKeeper's leader-based protocol for ordered, reliable state updates.
This is a historical learning note and may contain outdated or incomplete understanding.
ZAB (ZooKeeper Atomic Broadcast) is the leader-based atomic-broadcast protocol used by ZooKeeper to order and replicate state-changing transactions.
The detailed note lives in the ZooKeeper collection:
At a high level, ZAB combines leader election/recovery with an ordered broadcast phase so a quorum agrees on the transaction history used by the ZooKeeper state machine.