🛍️ Online Store Showcase | Reactive Spring Boot + Java 21

A modern, reactive web application demonstrating an online product catalog with full e-commerce functionality built with Java 21 and Spring Boot 3.

📋 Table of Contents

• Live Demo
• Technology Stack
• About The Project
  • User Roles & Features
  • Authentication & Security
  • Payment & Balance System
  • Technical Highlights
  • UI/UX Features
• How to Run
  • Using Docker (Recommended)
  • Local Development
• Testing

🚀 Live Demo & Quick Overview

🛠️ Technology Stack

Category	Technologies
Backend	Java 21, Spring Boot 3 (WebFlux, R2DBC, Security, OAuth2)
Databases	PostgreSQL, Redis (caching)
Infrastructure	Docker, Testcontainers
UI	Thymeleaf, HTML, CSS, JavaScript
Tools	Lombok, MapStruct, OpenAPI Generator

📋 About The Project

This web application serves as a fully-functional product showcase with e-commerce capabilities, built using reactive programming principles for better scalability and performance.

👤 User Roles & Features

Unauthenticated User

• Browse product catalog
• View product details

Authenticated User (registration/login required)

• Full cart management (add/remove items)
• Order placement, payment, and cancellation
• Product creation (stock replenishment)
• Session management with "Remember Me" functionality

🔐 Authentication & Security

• Two login modes:
  • Temporary session: Session expires when browser closes (default)
  • Persistent session: Session restored after browser restart ("Remember Me" enabled)
• OAuth 2.0 Authorization Server using Client Credentials Flow for payment service authorization
• "Remember Me" authentication uses Base64-encoded tokens to reconstruct full Authentication objects with UserDetails

💳 Payment & Balance System

• Default user balance: 15,000 RUB (configurable via payment.default-balance)
• Successful order cancellations refund the amount to user's balance
• Insufficient balance prevents payment with appropriate user notification

⚙️ Technical Highlights

Architecture & Performance

• Redis caching for user carts and product lists to reduce application load
• Reactive programming model with Spring WebFlux for better scalability
• @ControllerAdvice implementation for real-time cart total updates and dynamic UI state management

API & Integration

• Auto-generated client (showcase-service) and controller (payment-service) from OpenAPI specifications
• Service-to-service communication between showcase and payment services

Testing

• Comprehensive integration tests using Testcontainers
• Docker-in-Docker setup for executing Testcontainers tests within Docker containers

🎨 UI/UX Features

• Clear error messaging during registration and authentication
• Graceful degradation when payment service is unavailable:
  • Payment and cancellation buttons are disabled
  • Informative messages displayed to users
• Real-time balance validation with user feedback

🚀 How to Run

Using Docker (Recommended)

Run Only Tests (Showcase & Payment Services)

docker-compose --profile test up --build --abort-on-container-exit

Exit code 0 indicates all tests passed successfully.

Run Full Application (All 3 Services)

docker-compose --profile prod up -d

Application will be available at: http://localhost:8080/products

Stop Containers

To stop all running containers:

docker-compose down

To remove volumes:

docker-compose down -v

Local Development

Prerequisites:

• PostgreSQL running on port 5432
• Redis running on port 6379
• Docker Desktop (for Testcontainers)
• Maven 3.6+
• Java 21

Steps:

Build all services (including tests):

mvn clean package

(Optional) Build authorization service:

mvn clean install -pl auth-service

Run the showcase service:

java -jar showcase-service/target/showcase-service.jar --spring.profiles.active=prod

(Optional) Run payment service separately:

java -jar payment-service/target/payment-service.jar --spring.profiles.active=prod

Access the application at: http://localhost:8080/products

🧪 Testing

The project includes comprehensive testing:

• Unit tests with JUnit 5 and Mockito
• Integration tests with Testcontainers
• End-to-end Docker-based testing
• Code coverage tracking via Coveralls

🤝 Contributing

Feel free to fork the repository and submit pull requests for any improvements.

📄 License

This project is for demonstration purposes as part of a learning portfolio.

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Built with ❤️ using Spring Boot, Java 21, and reactive programming principles