Real-Time Discussion Platform (WebSocket Architecture)

Problem

Online communities are usually forced to pick one: slow-paced threaded discussions, or fast real-time chat. Splitting the two across separate tools kills engagement and context.

Solution

Built a MERN + Socket.IO platform that merges both worlds in one app — persistent discussion threads with comments live alongside real-time messaging, so a conversation can start async and move to live chat instantly.

Features

• 15+ REST APIs across Auth, Posts & Notifications
• JWT authentication with bcrypt password hashing
• Socket.IO — live chat, typing indicators & online presence
• Real-time notifications for replies, mentions & messages persisted to the DB
• Multi-emoji reactions, rich text posts, image uploads (Multer), @mentions with autocomplete
• Infinite scroll — feed loads in pages of 8 instead of fetching everything at once

Architecture

• Express REST API and a Socket.IO layer run side by side in the same Node process, sharing auth/session context
• MongoDB + Mongoose schema design across Users, Posts, Comments & Notifications collections
• Role-based authorization middleware guards protected routes on both REST and socket events
• Uploaded images served from server/uploads via Multer in dev — repo explicitly flags this needs to move to S3/Cloudinary for production since free-tier hosts use ephemeral disks

Technology Stack

Challenges

• Infinite scroll (paged fetch of 8) instead of loading the full feed, to keep initial payloads small as post volume grows
• Socket.IO falls back to HTTP long-polling when WebSocket transport isn't available
• Notification documents carry a type + link back to the source post, so read/unread state persists across sessions instead of living only in memory
• Known scaling gap called out directly: local-disk image storage won't survive redeploys on ephemeral hosts — next step is swapping in object storage

Results / Impact

Links