Watcher (Apache ZooKeeper - Server 3.9.1 API)

All Known Implementing Classes:

ControllableConnection, DumbWatcher, NettyServerCnxn, NIOServerCnxn, ServerCnxn
```
@Public
public interface Watcher
```
This interface specifies the public interface an event handler class must implement. A ZooKeeper client will get various events from the ZooKeeper server it connects to. An application using such a client handles these events by registering a callback object with the client. The callback object is expected to be an instance of a class that implements Watcher interface. When process(org.apache.zookeeper.WatchedEvent) is triggered by a watch firing, such as Watcher.Event.EventType.NodeDataChanged, WatchedEvent.getZxid() will return the zxid of the transaction that caused said watch to fire. If -1L is returned then the server must be updated to support this feature.

Nested Class Summary

Nested Classes
Modifier and Type	Interface	Description
`static interface`	`Watcher.Event`	This interface defines the possible states an Event may represent
`static class`	`Watcher.WatcherType`	Enumeration of types of watchers

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type Method Description

void process(WatchedEvent event)

- Method Detail
  - process
```
void process(WatchedEvent event)
```