Cap theory

Zookeeper be based on CP

1.Consistency（ Uniformity ）: For each read operation of the client , Or read the latest data , Either the read failed .
2.Availability（ Usability ）: Any client request can get response data , There are no response errors .
3.Partition tolerance（ Zone tolerance ）: Most distributed systems are distributed over multiple subnetworks . Each subnetwork is called a zone （partition）. Partition fault tolerance means , Interval communication may fail . such as , A server is in China , Another server is in the United States , These are the two areas , They may not be able to communicate with each other .

CAP In theory, a distributed system can't satisfy C、A、P These three characteristics
For a distributed system ,P It's the premise , Must ensure , Because as long as there is network interaction, there will be delay and data loss .
When chosen C（ Uniformity ） when , If the specific information cannot be guaranteed to be up-to-date due to network partition , The system will return an error or timeout .
When chosen A（ Usability ） when , The system will always process the client's queries and try to return the latest available version of information , Even if it cannot be guaranteed to be up-to-date due to network partition .