What is Zookeeper
Zookeeper is a distributed coordination service for managing mainframe. In a distributed environment, coordination and management services is a complex process. Zookeeper solve this problem through its simple architecture and API, Zookeeper allows developers to focus on core application logic without having to worry about the distributed nature of applications.
Zookeeper data model
Zookeeper data model look like? It's like among the data tree, much like the file system directory, Zookeeper is a standard binary tree structure
Tree is composed of nodes, the Zookeeper data storage node is also based, this node is called Znode
However, different from the node tree, znode the reference is a reference path, similar to a file path
/ Animal / dog
/ Automotive / BMW
Such a hierarchical structure, so that each node has a unique path Znode, like namespaces, make a clear separation of the different information
Znode which elements contained
data: the data Znode
ACI: Record Znode access to that who or what can access this IP node
state: containing Znode various metadata, such as transaction ID, version number, timestamp, size, etc.
child: a reference to the current node's children
It should be noted that: Zookeeper is a little reading and writing scene design, Znode do not want to store the massive business data, but for a small amount of storage status and configuration information, the maximum amount of data per node can not exceed 1MB
The basic operation of Zookeeper
Creating nodes
create
Delete Node
delete
Determine whether there is a node
exists
Obtaining data of a node
getData
Setting data of a node
setData
Gets all the child nodes of node
getChildren
Among these, exists, getData, getChildren read belongs, the Zookeeper client when requesting a read operation, the watch can select whether to set