Distributed: zookeeper: data storage server (tree structure)
In a distributed environment: network flash disconnection, reconnection mechanism... (data synchronization [efficiency, reliability, atomicity])
The principle of synchronous brushing, asynchronous brushing, and more than half of the ok pass
Watcher
Zookeeper has a watch event, which is triggered at one time. When the data monitored by the watch changes, it notifies the client that set the watch, that is, the watcher
Similarly, if its watcher is monitoring data to send some changes, there must be a corresponding event type and state type.
Event type: (znode node related)
EventType.NodeCreated
EventType.NodeDataChanged
EventType.NodeChildrenChanged
EventType.NodeDeleted
Status type: (is related to the client instance)
KeeperState.Disconnected
KeeperState.SyncConnected
KeeperState.AuthFailed
KeeperState.Expired