💬 Chat System

Github: github.com/le-minh-duc-dev/chat-system.git

This project is a full-featured chat platform built using Spring Boot microservices, designed for real-world system simulation and backend learning.
It supports:

1-to-1 and group messaging
User authentication and authorization
Real-time communication via WebSocket
Kafka for asynchronous message handling
Service discovery, centralized configuration, and API gateway routing

📑 Microservices

🧱 System Overview

System Design

This project is divided into multiple microservices:

Service	Description	GitHub
🛡️ Auth Service	Handles user registration, login, and JWT token issuance	auth-service
🔐 API Gateway	Central entry point for all services: JWT authentication, request routing, rate limiting, and circuit breaking	api-gateway
👥 User Service	Manages user profiles, including profile updates and public info exposure	user-service
💬 Chat Service	Manages WebSocket authentication, chat rooms, real-time messaging, user presence tracking, per-room read tracking and Snowflake ID generation	chat-service
📨 Message Service	Persists chat messages; supports infinite scroll, message history	message-service
🔧 Config Server	Provides centralized and version-controlled configuration management for all microservices	config-server
🔍 Eureka Server	Enables service discovery, instance registration, and health monitoring	eureka-server
🖥️ Frontend	React-based SPA client with chat UI, client-side routing via Tanstack Router, and optimized virtual list rendering for scalable message panels	frontend

🚀 Technologies Used

This project is built with a cloud-native microservices architecture, focusing on scalability, modularity, and real-time interaction.

🧠 Core Backend Technologies

Java 17+ – Modern Java language features and strong typing
Spring Boot – Framework for developing microservices with embedded servers
Spring Security – Authentication and authorization framework
JWT (JSON Web Token) – Stateless, token-based authentication
Spring Cloud Gateway – Reactive gateway for routing and filtering
Spring WebSocket (STOMP protocol) – Enables full-duplex real-time communication

📨 Messaging and Communication

Apache Kafka – Distributed event streaming platform
Spring for Apache Kafka – Kafka integration with Spring Boot
Kafka Topics:
- chat-messages – Chat message delivery and persistence
- presence-messages – Online status broadcasts
- command-messages – System commands to clients

💾 Caching, Rate Limiting & Session State

Redis – Used for:
- Caching
- Presence tracking
- WebSocket session tracking
- Redis Rate Limiter (via Spring Cloud Gateway)

🗄️ Databases

PostgreSQL – Relational database for structured data persistence (e.g., messages, users)
Spring Data JPA – Object-Relational Mapping (ORM) framework for PostgreSQL

🔍 Service Discovery & Configuration

Eureka Server – For service registration and load balancing
Spring Cloud Netflix Eureka Client – Enables microservices to register with Eureka
Spring Cloud Config Server – Centralized and Git-based external configuration

📦 Containerization & Deployment

Docker – Containerize each microservice for portability
Docker Compose – Define and run multi-container environments (ideal for local development)

🛠️ Developer Tools and Frameworks

Lombok – Simplifies Java boilerplate (e.g., getters, constructors)
Spring Cloud OpenFeign – Declarative REST clients for inter-service communication
Hibernate Validator – Bean validation for request DTOs

🖥️ Frontend (React SPA)

React + TypeScript – Strongly typed component-based UI development
TanStack Router – Modern routing library for single-page apps
TanStack Query (React Query) – Data fetching with intelligent caching and refetching
TanStack Virtual – Efficient list virtualization (infinite scroll support)
Redux Toolkit – Global state management (auth, UI, etc.)
HeroUI – Headless UI component library with accessibility
STOMP over WebSocket – Real-time chat via @stomp/stompjs
Axios – Promise-based HTTP client with JWT interceptor for refresh token logic

🧪 Monitoring & Observability

Spring Boot Actuator – Exposes health checks, metrics, and runtime endpoints
Resilience4j – Circuit breaker pattern integration for Gateway fault tolerance
Custom KeyResolvers – Used for user/IP-specific rate limiting

🧱 Architecture

Domain-driven Microservices Architecture – Clear separation of concerns and scalability
Stateless Services – Built to scale horizontally with no local state
Event-Driven Communication – Kafka-based asynchronous processing
WebSocket Scaling with Kafka – Cross-instance message fan-out

🙋‍♂️ About the Developer

This project is built by @le-minh-duc-dev as a learning project and portfolio showcase demonstrating modern backend engineering techniques.
It highlights:

Service communication patterns (Kafka and REST)
Stateless JWT-based security
Horizontal scalability practices
Microservice isolation for fault tolerance

Feel free to explore each repository for detailed implementations and design choices.