http://zh.wikipedia.org/wiki/%E9%A2%84%E5%86%99%E5%BC%8F%E6%97%A5%E5%BF%97
http://zookeeper.apache.org/doc/r3.3.6/bookkeeperStarted.html
http://zookeeper.apache.org/bookkeeper/docs/r4.0.0/bookkeeperProgrammer.html
http://zookeeper.apache.org/bookkeeper/docs/r4.0.0/apidocs/index.html?org/apache/bookkeeper/client/BookKeeper.html