zk-groupmembership

This package allows you to initialize a member group in zookeeper, monitor its members, and register one or more members.
This is useful for instance to manage the nodes when implementing consistent hashing.

Usage

ZKGroupMembership class

const ZKGroupMembership = require("zk-groupmembership").ZKGroupMembership;
const Zookeeper = require('node-zookeeper-client');
console.log("Using zk-groupmembership");
const client = Zookeeper.createClient(zkConnStr);
client.connect();

const group
    = new ZKGroupMembership(client, '/groups/sharding_example_cluster', {
    timeout: 10000, //Optional timeout for registering, getting members, getting data etc
    setupTimeout: 10000, //Optional timeout for the setup call.
});

group.setup()
    .then(() => group.registerMember()) //Register a member with a generated id and no associated data
    .then((member) => {
        console.log("Registered Instance %s", member.id);
        taskSharding.selfNode = member.id;
        group.startMonitor(); //will cause the 'members', 'error' events to be emitted on the group instance.
    }).catch(err => {
    console.log("Couldn't participate in cluster:%s\%s", err.message, err.stack);
    process.exit(1);
});

Events

group.on('error', err => {
    console.log("Cluster Error:%s\%s", err.message, err.stack);
    process.exit(1);
});
group.on('members', nodes => {
    currentNodeCount = nodes.length;
    taskSharding.setNodes(nodes);
});

Running the example

Please look here

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality, lint and test your code.

• To run lint and tests:

  npm test
  npm run lint