Introduction to node-redis-pubsub

The node-redis-pubsub module is a powerful and efficient library that leverages Redis for creating a scalable and performant publish-subscribe messaging system. Whether you are building a real-time chat application, a notification system, or any other real-time service, node-redis-pubsub will simplify your workflow and enhance performance.

Installation

npm install node-redis-pubsub

Basic Usage

Below is a simple example demonstrating how to publish and subscribe to messages using node-redis-pubsub:

  const NodeRedisPubsub = require('node-redis-pubsub');
  const config = { port: 6379, host: '127.0.0.1' };
  const nrp = new NodeRedisPubsub(config);

  // Subscribing to a channel
  nrp.on('message', (data) => {
    console.log('Received message:', data);
  });

  // Publishing a message
  nrp.emit('message', { text: 'Hello, World!' });

Advanced Usage

Explore more advanced scenarios, including pattern-based subscriptions and handling Redis errors:

Pattern-Based Subscriptions

  // Subscribing to all channels with the given pattern
  nrp.patternSubscribe('news.*', (data) => {
    console.log('Received news:', data);
  });

  // Publishing a message to a pattern-matching channel
  nrp.emit('news.sports', { headline: 'Local team wins!' });

Error Handling

  nrp.on('error', (err) => {
    console.error('Redis error:', err.message);
  });

App Example

Let’s create a simple application demonstrating real-time chat functionality using node-redis-pubsub:

  const express = require('express');
  const http = require('http');
  const socketIo = require('socket.io');
  const NodeRedisPubsub = require('node-redis-pubsub');

  const app = express();
  const server = http.createServer(app);
  const io = socketIo(server);
  const config = { port: 6379, host: '127.0.0.1' };
  const nrp = new NodeRedisPubsub(config);

  app.get('/', (req, res) => {
    res.sendFile(__dirname + '/index.html');
  });

  io.on('connection', (socket) => {
    console.log('a user connected');

    socket.on('chat message', (msg) => {
      nrp.emit('chat', { message: msg });
    });

    nrp.on('chat', (data) => {
      io.emit('chat message', data.message);
    });
    
    socket.on('disconnect', () => {
      console.log('user disconnected');
    });
  });

  server.listen(3000, () => {
    console.log('listening on *:3000');
  });

With these examples, you can see how easily node-redis-pubsub integrates with your application to provide robust and scalable real-time messaging solutions.

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