Topic-based messaging in Firebase - Mini Project: Build & Apply

Firebase Topic-Based Messaging Setup

📖 Scenario: You are building a mobile app that sends notifications to users based on their interests. You want to use Firebase Cloud Messaging (FCM) to send messages to groups of users subscribed to specific topics.

🎯 Goal: Create a Firebase Cloud Messaging setup that subscribes users to a topic, configures a message payload, sends a message to the topic, and completes the messaging configuration.

📋 What You'll Learn

Create a topic subscription variable

Add a message configuration object

Send a message to the topic using Firebase Admin SDK

Complete the messaging setup with proper topic and message structure

💡 Why This Matters

🌍 Real World

Topic-based messaging allows apps to send notifications to groups of users interested in specific subjects, like news or sports updates.

💼 Career

Understanding Firebase topic messaging is useful for cloud engineers and mobile developers who build scalable notification systems.

1

Create a topic subscription variable

Create a variable called topic and set it to the string "news" to represent the topic users will subscribe to.

Firebase

// Create a variable called topic and set it to "news"
// Your code here

Need a hint?

Use const topic = "news"; to define the topic name.

2

Add a message configuration object

Create a constant called message that is an object with a notification property. The notification should have title set to "Breaking News" and body set to "New updates available.". Also add a topic property set to the variable topic.

Firebase

const topic = "news";
// Create a message object with notification title and body, and topic property
// Your code here

Need a hint?

Define message as an object with notification and topic properties.

3

Send a message to the topic using Firebase Admin SDK

Use the Firebase Admin SDK's messaging().send() method to send the message object. Assign the result to a constant called response. Use await to wait for the send operation to complete.

Firebase

const topic = "news";
const message = {
  notification: {
    title: "Breaking News",
    body: "New updates available."
  },
  topic: topic
};

// Send the message using Firebase Admin SDK and assign the result to response
// Your code here

Need a hint?

Use await admin.messaging().send(message); and assign it to response.

4

Complete the messaging setup with proper topic and message structure

Add a subscription call using admin.messaging().subscribeToTopic() to subscribe an array with a single token "user_token_123" to the topic. Assign the result to a constant called subscribeResponse using await.

Firebase

const topic = "news";
const message = {
  notification: {
    title: "Breaking News",
    body: "New updates available."
  },
  topic: topic
};

const response = await admin.messaging().send(message);

// Subscribe the token "user_token_123" to the topic and assign the result to subscribeResponse
// Your code here

Need a hint?

Use await admin.messaging().subscribeToTopic(["user_token_123"], topic); and assign it to subscribeResponse.