A data structure
zookeeper is a tree structure of a znode nodes, each node can contain sub nodes and data, and the client can monitor each node (i.e., set the monitor).
Second, znode type of (short-type and long-lasting type)
When creating znode setting sequence identity , appends a value znode name, is a monotonically increasing sequence number counter, maintained by the parent node.
1. Persistence of znode (once created will not be lost)
create /aaa helloworld
2. The order of znode (create a znode, the system will append your znode above a 10-digit number)
-S command to create sequential znode,
create /aaa
create -s /aaa/b1 hello1
create -s /aaa/b2 hello2
ls /aaa
3. temporary znode (ZooKeeper is down, or client within the time specified in the session is not connected server, will be considered lost)
client -> server connection length [tcp] + session mechanism
If you think client server crash or restart the zookeeper, znode client will delete previously created
-E command to create a temporary znode
create -e /aaa/b3 hello3
+ 4. Create a temporary
order of nodes
create -s -e /aaa/b4 hello4
Three, znode properties ( GET / aaa )
Each node ZNode while storing data, are known to maintain a data structure of Stat, which stores information about all the states of the node.
Transaction ID when creating czxid data node
The creation of ctime time data node
When the transaction ID data node mzxid last update
Mtime time of last update node data
pzxid data node subnode last transaction ID is modified when
Changing the number of child nodes cversion
Change the version number of the node data
ACL's aversion to change the number of nodes
ephemeralOwner If the node is a temporary node, the created session SessionID the node; if the node is a persistent node, the attribute value is 0
The length of the data content dataLength
The number of child nodes of the current node data numChildren