IMDG orange logo square
node

Welcome to «The Distributed World» of Hazelcast. Here are sample usages of distributed data structures using Node.js client.

Table 1. Revisions history
VersionDateComments

v1.1

03/09/2015

single quotes in js code, added Before Getting Started section

v1.0

02/07/2015

Initial revision

The JavaScript examples use ES6 syntax

Before Getting Started

  • download latest Hazelcast distribution from https://hazelcast.org/download/

  • unzip to any folder

  • start Hazelcast member using startup script <hazelast_folder>/bin/start.sh

before nodejs client

Configure Node.js client

Install Hazelcast Client Node.js Package
npm install hazelcast-client --save
const HazelcastClient = require('hazelcast-client').Client; (1)
const Config = require('hazelcast-client').Config;  (2)

let config = new Config.ClientConfig(); (3)

HazelcastClient.newHazelcastClient(config)
    .then((client) => {   (4)
        // use client object
});
1import HazelcastClient object
2import Config object
3establish connection to local cluster member using default config
4fully constructed and connected client will be passed as parameter

Distributed Map

HazelcastClient.newHazelcastClient().then((client) => {
    let map = client.getMap('my-distributed-map');
    map.put('key', 'value')
        .then(() => map.get('key'))
        .then(() => map.putIfAbsent('somekey', 'somevalue'))
        .then(() => map.replace('key', 'oldvalue', 'newvalue'))
});

Distributed MultiMap

HazelcastClient.newHazelcastClient().then((client) => {
    'use strict';
    let mmap = client.getMultiMap('restaurants');

    mmap.put('New York', 'Red Lobster')
        .then(() => mmap.put('New York', 'Eataly'))
        .then(() => mmap.get('New York'))
        .then(list => console.log(list));

    mmap.put('Las Vegas', 'Burgr')
        .then(() => mmap.put('Las Vegas', 'Alibi'))
        .then(() => mmap.put('Las Vegas', 'Pub & Grill'))
        .then(() => mmap.get('Las Vegas'))
        .then(list => console.log(list));
});

Distributed List

HazelcastClient.newHazelcastClient().then((client) => {
    'use strict';
    let list = client.getList('my-distributed-list');

    let element = 'element1';
    list.add(element).then(() => {
        list.contains(element).then((result) => {
            console.log(`contains element1 - ${result}`);
        });
    });

    let elements = ['element2', 'element3'];
    list.addAll(elements).then(() => {
        list.containsAll(elements).then((result) => {
            console.log(`contains all element1 - ${result}`);
        })
    });
});

Distributed Set

A set is a data structure that doesn’t allow duplicates
HazelcastClient.newHazelcastClient().then((client) => {
    'use strict';
    let set = client.getSet('my-distributed-set');

    let elements = ['duplicate', 'duplicate', 'duplicate'];
    set.addAll(elements).then(() => {
        set.getAll().then((result) => {
            //look, ma, no duplicates
            console.log(result);
        })
    });
});

Distributed Queue

HazelcastClient.newHazelcastClient().then((client) => {
    let queue = client.getQueue('my-distributed-queue');

    queue.offer('item');
    queue.poll().then(item => console.log(item));

    queue.offer('anotheritem', 500);
    queue.poll(5000).then(item => console.log(item));

    queue.offer('yetanotheritem');
    queue.take().then(item => console.log(item));

});

Distributed Lock

HazelcastClient.newHazelcastClient().then((client) => {
    let lock = client.getLock('my-distributed-lock');

    lock.lock().then(() => {
        // do something
    });

    lock.unlock();
});

Distributed Topic

HazelcastClient.newHazelcastClient().then((client) => {
    let topic = client.getReliableTopic('my-distributed-topic');

    topic.addMessageListener((msg) => {
        console.log(msg.messageObject);
    });
    topic.publish('hello from distributed world');
});

About Hazelcast IMDG

Hazelcast is an open-source in-memory data grid providing Java developers with an easy-to-use and powerful solution for creating highly available and scalable applications. Hazelcast can be used in the areas like clustering, in-memory NoSQL, application scaling, database caching.

Resources