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Real-time Like Notifications with Redis Pub/Sub in CampusX

Introduction Handling real-time events efficiently is crucial in any social media-like application. In CampusX, I implemented Redis Pub/Sub to manage like notifications seamlessly. This approach ensures that when a user likes a post, the owner of the post receives an instant notification via WebSockets. This blog will break down how Redis Pub/Sub works and how it powers the real-time like notifications in CampusX. What is Redis Pub/Sub? Redis Pub/Sub (Publish/Subscribe) is a messaging system where publishers send messages to specific channels, and subscribers listening to those channels receive the messages instantly. Unlike traditional message queues, Redis Pub/Sub does not store messages. Once a message is delivered to all subscribers, it disappears from memory. Key Components: Publisher: Sends messages to a Redis channel. Subscriber: Listens for messages on a channel. Channel: A topic where messages are broadcasted. Setting Up Redis Pub/Sub for Like Notifications in CampusX 1️⃣ Configuring Redis Client First, I created a Redis configuration file (redis.js) to manage the publisher and subscriber connections: import { createClient } from "redis"; const pub = createClient(); const sub = createClient(); pub.on("error", (err) => console.error("❌ Redis Publisher Error:", err)); sub.on("error", (err) => console.error("❌ Redis Subscriber Error:", err)); async function connectRedis() { try { await pub.connect(); console.log("✅ Redis Publisher Connected"); await sub.connect(); console.log("✅ Redis Subscriber Connected"); } catch (err) { console.error("❌ Redis Connection Error:", err); } } connectRedis(); export { pub, sub }; This ensures that both the publisher and subscriber are connected when the backend starts. 2️⃣ Publishing Like Events Whenever a user likes a post, the backend publishes a message on the like_status channel: import { pub } from "../config/redis.js"; async function publishLikeStatus(status, postOwnerId, userId) { console.log("Published Like Status"); if (!pub.isReady) { console.log("

Mar 14, 2025 - 14:35
 0
Real-time Like Notifications with Redis Pub/Sub in CampusX

Introduction

Handling real-time events efficiently is crucial in any social media-like application. In CampusX, I implemented Redis Pub/Sub to manage like notifications seamlessly. This approach ensures that when a user likes a post, the owner of the post receives an instant notification via WebSockets.

This blog will break down how Redis Pub/Sub works and how it powers the real-time like notifications in CampusX.

What is Redis Pub/Sub?

Redis Pub/Sub (Publish/Subscribe) is a messaging system where publishers send messages to specific channels, and subscribers listening to those channels receive the messages instantly. Unlike traditional message queues, Redis Pub/Sub does not store messages. Once a message is delivered to all subscribers, it disappears from memory.

Key Components:

  • Publisher: Sends messages to a Redis channel.
  • Subscriber: Listens for messages on a channel.
  • Channel: A topic where messages are broadcasted.

Setting Up Redis Pub/Sub for Like Notifications in CampusX

1️⃣ Configuring Redis Client

First, I created a Redis configuration file (redis.js) to manage the publisher and subscriber connections:

import { createClient } from "redis";

const pub = createClient();
const sub = createClient();

pub.on("error", (err) => console.error("❌ Redis Publisher Error:", err));
sub.on("error", (err) => console.error("❌ Redis Subscriber Error:", err));

async function connectRedis() {
  try {
    await pub.connect();
    console.log("✅ Redis Publisher Connected");
    await sub.connect();
    console.log("✅ Redis Subscriber Connected");
  } catch (err) {
    console.error("❌ Redis Connection Error:", err);
  }
}

connectRedis();

export { pub, sub };

This ensures that both the publisher and subscriber are connected when the backend starts.

2️⃣ Publishing Like Events

Whenever a user likes a post, the backend publishes a message on the like_status channel:

import { pub } from "../config/redis.js";

async function publishLikeStatus(status, postOwnerId, userId) {
  console.log("Published Like Status");

  if (!pub.isReady) {
    console.log("
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