Live Location Tracker

A hobby project to track real-time live locations using WebSockets (Socket.io) and Apache Kafka for reliable message streaming.

Architecture & How Things Work

1. Clients (Browsers/Apps) connect to the Node.js server via Socket.io.
2. Location Updates: Clients emit their location data to the server (client:location:update).
3. Kafka Producer: The Node.js server acts as a Kafka producer, sending the received location data into the location-updates Kafka topic.
4. Kafka Consumers:
   • Socket Server Consumer: The server also consumes the location-updates topic and broadcasts the locations back to all connected clients via Socket.io (server:location:update).
   • Database Processor: A separate worker (database-processor.js) independently consumes the same location-updates topic to persist the location data into a database (currently mocked).

This architecture ensures that high-volume location updates are reliably buffered, processed asynchronously, and broadcasted efficiently.

Prerequisites

• Node.js (v18+ recommended)
• Docker and Docker Compose (for running Kafka)

How to Start Locally

Follow these steps to run the complete setup on your local machine:

1. Install Dependencies

npm install

2. Start Kafka Infrastructure

Start the Apache Kafka broker using Docker Compose:

docker compose up -d

3. Setup Kafka Topics

Once Kafka is running, initialize the required topic (location-updates):

node kafka-admin.js

You should see a message confirming that the Kafka admin connected and topics were created.

4. Start the Application Services

You will need to open two terminal windows to run both services:

Terminal 1: Start the Main Server This will start the Express web server and Socket.io handler.

npm run dev
# or
npm start

The server will start on port 5000 (default) and connect to Kafka.

Terminal 2: Start the Database Processor This simulates the worker that processes and saves locations to a database.

node database-processor.js

Exploring the App

Once everything is running:

• The server exposes a health check endpoint at http://localhost:5000/health.
• Any frontend files placed in the public/ directory will be served automatically at http://localhost:5000/.
• Connect your Socket.io client to http://localhost:5000 to start emitting and listening to location events!