Real-Time Chat with Microservices 🚀

A scalable real-time chat application built with microservices architecture. Supports instant messaging, presence status, and push notifications.

Tech Stack 🛠️

Microservice	Responsability	Technologies
WebSocket Service	To handle real-time connections (WebSocket)	Golang + WebSockets
Message Service	Store/retrieve messages	Golang + MongoDB
Presence Service	Manage user status (online/offline)	Golanng + Redis
Auth Service	Authenticate users and validate tokens	Golang + Postgres + JWT
Notification Service	Notify events (e.g. new messages)	RabbitMQ
API Gateway	Request routing and management	NGINX

Operation Flow 🔧

a. Initial User Connection

1. Authentication:
   • Client sends credentials to Auth Service using HTTP
   • The Auth Service returns a JWT for access to other services.
2. WebSocket connection:
   • API Gateway service validates tokens using Public key (RSA)
   • The client establishes a WebSocket connection with the WebSocket Service, including user information in the headers.

b. Message Sending

1. The client sends a message via WebSocket.
2. The WebSocket Service publishes the message to a message broker.
3. The WebSocket Service consumes the message from the broker and sends it to the users.
4. The Message Service consumes the message from the broker and persists it to the database.
5. The Notification Service consumes the message from the broker and notifies users.

c. Presence Status

1. When a user connects, the WebSocket Service notifies the Presence Service and updates its status to "online" (e.g. using Redis to store state).
2. When disconnecting, the WebSocket Service notifies the Presence Service to update the status to "offline".

d. Notifications

• The Notification Service listens to broker events (e.g. new message) and sends push notifications

3. Communication Between Services

• Synchronous (HTTP/REST/gRPC):
• Refresh token validation and message history query.
• Asynchronous (Message Broker):
• Message events, status updates and notifications.
• WebSocket:
• Real-time communication between client and server.

TODO

• Adicionar Dead letter queue no rabbitmq para persistir mensagens