mini-message-board - Live Preview

About

This project is part of the assignment from The Odin Project. As you may notice, I did more work than it was required, just for fun and because it was easier to practice new knowledge on an existing project.

I have also learned about the WebSocket protocol in order to implement live-chat capability. The number of active users is updated as users connect/disconnects, and messages are seen in real-time.

How It Works

I specifically want to cover the WSS (Web Socket Server). Like any server, once it runs, it wait for client requests in order to give a response back. It's event-driven too, just like ExpressJS, and it needs to be implemented on both sides, frontend and backend.

On backend, we create the WSS server. And on frontend, we use the in-built WebSocket API to connect to the WSS server and send data.

Initially, WSS uses the HTTP protocol, but then it's upgraded to the WebSocket protocol which allows a client to exchange data with the server without making actual requests (as you may notice in DevTools > Network tab), which means real-time updates.

The way number of connected users is tracked is by using wss.on('connection') and ws.on('close') events on backend-side, and ws.on('open') on frontend side.

Try to imagine this: you have two physical pipes (one in left, one in right), and you need another smaller pipe to connect both. On the left side we have the client, and on the right we have the server. That smaller pipe is the WebSocket protocol, which acts like a tunnel. Once it connects the other two, information can be exchanged in real-time

Tech Stack

Frontend: EJS templates rendered on the server
Backend: NodeJS + ExpressJS
- Authentication:
  - passportjs: to validate/invalidate the authentication process
  - express-session: to create a session in order to save and exchange client's state
  - connect-pg-simple: to connect to the database in order to store the session there ins****tead of the server's memory
  - jsonwebtoken: used as an additional security layer for practice purposes
- Database: PostgreSQL
Deployment: Koyeb for the server, and Neon for the database - a good combo because of their free plans

Project Structure

┣ 📂authentication ┣ 📂controllers ┣ 📂database ┣ 📂public ┃ ┣ 📂css ┃ ┣ 📂data ┃ ┗ 📂js ┣ 📂routes ┣ 📂views ┃ ┣ 📂pages ┃ ┗ 📂partials ┣ 📜.env.dev ┣ 📜app.js ┗ 📜utils.js

authentication: self-explanatory I guess? I can't really break it down into simpler words.
database: all the authentication credentials and messages are stored here
routes: available endpoints for the website. Think of it like a path in the file manager 😉
controllers: basically, functions that are bound to routes (endpoints), and runs automatically as soon as an endpoint is accessed/visited by the client
public: CSS and JS that gets loaded on the client
views: HTML templates that are dynamically generated before they are sent to the client. Partials contains smaller components that are included in the main pages.
utils: additional functions that are used here and there
app.js: is where the servers (both, HTTP & WebSocket protocols) are created and started

Setup

This assumes you have npm and nvm installed, you want to run it locally and you already created a PostgreSQL database in your system.

Clone the repo.
Run npm install.
Set up environment variables in a .env.dev file.
Run npm run dev.

Example of .env.dev (don't include </>):