As a bird’s eye view, Apache Zookeeper has been leveraged to get coordination services for managing distributed applications. It holds responsibility for providing configuration information, naming, synchronization, and group services over large clusters in distributed systems. As an example, Apache Kafka uses ZooKeeper for choosing their leader node for the topic partitions. Please click here if you want to read how to set up the multi-node Apache Zookeeper cluster on Ubuntu/Linux.
ZNodes
The key concept of ZooKeeper is the ZNode, which can act as either files or directories. ZNodes can be replicated between servers as they are working in a distributed file system. A ZNode can be described by a data structure called stats, and it consolidates information about ZNode context like creation time, number of changes (as version), number of children, length of stored data or ZXID (ZooKeeper transaction ID) of creation, and last change.