Collab

Collab is a multilingual real-time chat app built as a monorepo with a microservice-style architecture. Services communicate over HTTP, WebSocket, gRPC, and Redis — each one scoped to a single responsibility.

Stack

Next.js · WebSocket · gRPC · Redis Pub/Sub + Streams · PostgreSQL · Prisma

Overview

The idea is simple: split the work across focused services so each piece stays small, testable, and independently scalable.

• web — Next.js frontend. Auth, room listing, chat UI.
• http-service — REST APIs for users and rooms. Also issues short-lived WebSocket tickets.
• ws-service — Holds WebSocket connections, validates tickets, pushes live updates to clients.
• chat-service — Handles message operations (create, edit, delete, fetch) and publishes events to Redis.
• db-service — Exposes gRPC APIs for rooms, users, and messages. Runs a background worker that drains Redis streams into PostgreSQL.

Architecture

Request Flow

1. Client calls http-service to get a short-lived WebSocket ticket.
2. Client connects to ws-service using that ticket.
3. Client sends a message through chat-service.
4. chat-service fetches room/member data from db-service over gRPC.
5. chat-service publishes the message to Redis Pub/Sub.
6. ws-service picks it up and pushes it to connected clients in real time.
7. db-service consumes from the Redis stream and persists the message to PostgreSQL.

Why this structure

Keeping services separate means the WebSocket layer can scale independently from the database layer. Redis handles fast fan-out so ws-service never has to know about storage, and db-service never has to know about live connections. Each service has one job and one reason to change.