9.0 Zookeeper Node Features
Category Zookeeper Tutorial
This section introduces the node features of Zookeeper and simple usage scenarios. It is due to these node features that Zookeeper can develop different application scenarios.
1. Keys at the same level are unique
Example:
$ ls /
$ create /tutorialpro 2
If the /tutorialpro node already exists, attempting to create it again will prompt that it already exists.
2. When creating a node, the full path must be provided
Example:
$ ls /tutorialpro
$ create /tutorialpro/child 0
$ create /tutorialpro/child/ch01 0
3. Temporary nodes are cleared when the session closes
Example:
$ ls /tutorialpro
$ create -e /tutorialpro/echild 0
Check the node in another terminal:
$ ls /tutorialpro
After closing the first terminal connection with ctrl+c
, the /tutorialpro/echild node disappears in the second terminal.
$ ls /tutorialpro
4. Automatically create sequential nodes
Example:
$ create -s -e /tutorialpro 0
5. Watch mechanism, monitoring node changes
The event listening mechanism is similar to the observer pattern. The watch process involves the client registering a watcher with the server on a node path, and the client also storing a specific watcher. When the node data or child nodes change, the server notifies the client, which then performs callback processing. Note: The watch event is triggered only once and then becomes invalid.
Tip: Refer to the common commands section for using the get command to watch with watch. The implementation principles of watch will be detailed in later sections.
6. The delete command can only delete layer by layer
Example:
$ ls /
$ delete /tutorialpro
Tip: Newer versions can use the deleteall
command for recursive deletion.
With these various node features, Zookeeper can develop different classic application scenarios, such as:
- Data publishing/subscription
- Load balancing
- Distributed coordination/notification
- Cluster management
- Master management
- Distributed locks
- Distributed queues
-1.0 Zookeeper Tutorial -2.0 Zookeeper Installation and Configuration -3.0 Zookeeper Linux Server Cluster Setup Steps -4.0 Zookeeper Java Client Setup -5.0 ZooKeeper Data Model znode Structure Detailed -6.0 Zookeeper Session Basic Principles -7.0 Zookeeper Basic Client Commands Usage -8.0 Zookeeper Four-Letter Commands
- 9.0 Zookeeper Node Features -10.0 Zookeeper Access Control ACL -11.0 Zookeeper Watcher Event Mechanism Principles Analysis -12.0 Zookeeper Data Synchronization Process -13.0 Zookeeper Leader Election Principles -14.0 Zookeeper Distributed Lock Implementation Principles