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🛒 OMS System - Order System Architecture

🔍 Overview

OMS System is an e-commerce application built using Microservices Architecture and Domain-Driven Design (DDD) principles. The system is designed to simplify business processes, improve efficiency, and enable scalability.

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🎯 Objectives & Key Features

• Resilience: The system remains functional even if a component fails.
• Scalability: Handles high traffic and large volumes of transactions.
• Faster Development: Microservices enable independent team development.
• Monitoring & Debugging: Full observability with Zipkin, MailDev, and Eureka.

🔧 Core Capabilities

• Customer, product, order, and payment management.
• Email notifications for order and payment confirmations.
• Communication between services via REST (OpenFeign, RestTemplate) and Kafka.
• Centralized configuration, service discovery, and OAuth2-based security.

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🧱 System Architecture

The system is composed of independent microservices, each focused on a specific business domain:

Domain	Microservice	Database
Customer	Customer management (info + address)	MongoDB
Product	Product and category management	PostgreSQL
Order	Order and order line processing	PostgreSQL
Payment	Payment recording and handling	PostgreSQL
Notification	Email notification service	MongoDB (optional/stateless)

🏗️ Infrastructure Components

• Config Server: Centralized configuration management.
• Eureka Discovery Server: Service registration and discovery.
• API Gateway: Route and secure requests.
• Keycloak: OAuth2-based authentication and authorization.
• Kafka: Event-driven communication for order and payment flows.
• Zipkin: Distributed tracing.
• MailDev: Local SMTP server for testing email functionality.

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⚙️ Technologies & Tools

• Spring Boot, Spring Cloud, Spring Security
• MongoDB, PostgreSQL, Flyway
• Apache Kafka, JavaMailSender, Thymeleaf
• Docker Compose, Keycloak, Zipkin, MailDev
• IntelliJ IDEA, Postman, PG Admin, Mongo Express

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🚀 Getting Started

1. Clone the repository:

   git clone https://github.com/your-repo/oms-system.git
   cd oms-system

2. Run with Docker Compose:

   docker-compose up -d

3. Access management tools:

   • Eureka Dashboard: http://localhost:8761
   • MailDev: http://localhost:1080
   • Zipkin: http://localhost:9411
   • Keycloak: http://localhost:8080
   • Mongo Express: http://localhost:8081
   • PG Admin: http://localhost:5050

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🔐 Security with Keycloak

• Uses Keycloak as the OAuth2 Authorization Server.
• Each microservice acts as a resource server.
• Uses Client Credentials Grant for secure service-to-service communication.
• API testing supported via Postman with OAuth2 tokens.

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🧪 Testing & Observability

• API Testing: Postman collections available.
• Database Access: Use Mongo Express and PG Admin.
• Email Testing: Verify emails using MailDev.
• Distributed Tracing: Monitor service calls with Zipkin.

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📂 Project Structure

oms-system/
│
├── customer-service/
├── product-service/
├── order-service/
├── payment-service/
├── notification-service/
├── config-server/
├── discovery-server/
├── api-gateway/
├── docker-compose.yml
├── README.md

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📚 References

Documentation and source references are labeled with citations ([1], [2], ...) in the source code. See the docs/ directory or comments for detailed explanations.

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💡 Notes

• Each service can be scaled independently based on workload.
• Event-driven design with Kafka increases fault tolerance and decoupling.
• Easily extendable with additional features like cart, coupons, or product reviews.

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👨‍💻 Contributions

Contributions are welcome! Feel free to open an issue or submit a pull request.

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📜 License

Distributed under the MIT License. See the LICENSE file for more information.

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