Pub/Sub Redis for Nodejs

Lightweight abstraction of nodejs' Redis Pub/Sub feature. The module consists of a singleton class for the publisher and a subscriber class that can have multiple instances.

Install

$ npm install redis_pubsub      

Usage

Setup

/*** PUB CODE ***/

var Publisher    = require('redis-pubsub').Publisher;

var args = {
  options :{
    channel: 'mainchannel',
    host  : 'localhost',
    port  : 6379,   
  },
  /* 
    Callback function that will be callede when 
    the publisher is ready
  */
  readyCB : function() {
    console.log('Publisher is ready')
  },
};

var pub = new Publisher(args);

/*** SUB CODE ***/
var Subscriber    = require('redis-pubsub').Subscriber;

var args = {
  options :{
    channel: 'mainchannel',
    host  : 'localhost',
    port  : 6379,   
  },
  /* 
    Callback function that will be called when 
    the publisher is ready
  */
  readyCB : function() {
    console.log('Subscriber is ready')
  },
};

var sub1 = new Subscriber(args);
var sub2 = new Subscriber(args);

Alternatively you can use the Redis URI

var Subscriber    = require('redis-pubsub').Subscriber;

var args = {
  options: {
    channel: 'mainchannel',
  }
  redisURI: 'redis://:password@hostname:port/db_number'
  readyCB : function() {
    console.log('Subscriber is ready')
  },
};

Publishing and Subscribing

/*** PUB CODE ***/
var sub1_id = 1;
var sub2_id = 1;
pub.publish("This is my message for sub1", sub2_id)
pub.publish("This is my message for sub2", sub2_id)

/*** SUB CODE ***/
sub1.subscribe(function(mesage){
  console.log(message);
  //Should be 'This is my message for sub1'
})

sub1.subscribe(function(mesage){
  console.log(message);
  //Should be 'This is my message for sub1'
})

sub1.unsubscribe()
sub2.unsubscribe()

API Reference

Publicer

Publicer is a singleton Object that has some methods regarding. Connection and message publishing

Publicer(args)

Initialize the Publicer instance with specific arguments. This can be the following

Argument	Default	Description
redisURI	null	This option can be used to connect to redis instance via URI. An example is shown in the code above
readyCB	function() {}	This is the function to be called after the instance is ready
options	{host: '127.0.0.1', port: 6379, channel: 'main'}	The options used when connecting to Redis. Most of them can be found here

Publicer.client()

Returns the instance of the Redis client created by the node-redis api

Publicer.publish(payload[, channel])

Publish a message to the channel. payload is the data to send in a string. Channel can be either empty, a channel name or a subscriber id. In the first case the message is sent to the channel defined in the initialization, in the second case the message is sent to the arbitary channel name, and in the third case it is sent on the *channel*:*sid* where channel is the initial channel name and sid the id of the subscriber.

Subscriber

Subscriber is a class that can be instanciated multiple times in order to create multiple subscribers

Subscriber(args)

The arguments used when constructin a Subscriber object are the same as in Publicer object.

Subscriber.client()

Returns the instance of the Redis client created by the node-redis api

Subscriber.subscribe(callback)

Subscribe to the channel used in the construction of the object. The callback will be called only if a message is published on the id specific channel

Subscriber.unsubscribe()

Unsubscribe from all channels and terminate the client