Ordexa

🛒 Ordering Microservices Architecture

A production-ready, scalable Ordering System built with modern tools — powered by Bun, PostgreSQL, Apache Kafka, Cassandra, and CQRS + Event-Driven architecture.

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🚀 Tech Stack

Layer	Technologys used	Purpose achieved
Frontend	Bun + Vite	Lightning-fast SPA
Backend	Express (Bun)	REST APIs for orders
ORM	Prisma	DB access (PostgreSQL)
Write DB	PostgreSQL	Normalized transactional store
Read DB	Cassandra	Fast denormalized queries
Messaging	Apache Kafka	Real-time event streaming
Event Pattern	Outbox + CQRS	Consistency between DB and Kafka
Testing	Bun test + GitHub CI	Fast test automation

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📐 Architecture Overview

          [Frontend (Vite + Bun)]
                    │
                    ▼
[Express API (Bun)] --(Prisma)--> [PostgreSQL]
│                                     │
└---------> [Outbox Table] <----------┘
                    │
                    ▼
             [Kafka Producer]
                    │
                    ▼
              [Kafka Broker]
                    │
                    ▼         
             [Kafka Consumer]
                    │
                    ▼
               [Cassandra]

🧠 Key Concepts

✅ CQRS (Command Query Responsibility Segregation)

• Write Side (PostgreSQL): Handles commands — create, update, cancel orders.
• Read Side (Cassandra): Handles queries — get orders by user, by status, etc.

✅ Outbox Pattern

Ensures consistency by writing Kafka events after successful DB transactions.

✅ Kafka Event Flow

• Events: order.created, order.updated
• Message Format: JSON/Avro
• Consumers update Cassandra views

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🧪 Testing & CI

• bun test for unit and integration tests
• GitHub Actions pipeline runs:
  • Dependency install
  • Bun tests
  • Optional Docker services for Kafka/Postgres testing

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📦 Folder Structure

ordering-microservices/
├── apps/
│ ├── frontend/ # Bun + Vite (React)
│ └── backend/ # Bun + Express + Prisma
│ ├── src/
│ │ ├── api/ # Express routes & handlers
│ │ ├── services/ # Order logic, outbox logic
│ │ ├── kafka/ # Producer/consumer logic
│ │ ├── db/ # Prisma schema & PostgreSQL logic
│ │ └── cassandra/ # Cassandra query logic
│ ├── tests/ # Bun test cases (unit + integration)
│ └── bunfig.toml # Bun config file
│
├── infra/
│ ├── docker-compose.yml # Full stack (Kafka, PostgreSQL, Cassandra)
│ ├── kafdrop.yml # Kafka UI dashboard
│ └── test.override.yml # Docker Compose override for testing
│
├── .github/
│ └── workflows/
│ └── test.yml # GitHub Actions CI workflow
│
├── README.md # You're here
└── LICENSE # Open-source license

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🔒 Security & Scalability Features

• UUIDs for all IDs (collision-free)
• UTC timestamps everywhere
• Idempotent Kafka consumers
• Dead Letter Queues (DLQs) support
• Retry, backoff, observability-ready

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🔍 Future Enhancements

• 🔁 Saga Pattern for distributed workflows (Order → Payment → Ship)
• 🔍 Redis + Elasticsearch for caching and search
• 📊 Prometheus + Grafana + Loki for observability
• 🧪 Playwright for E2E testing

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🛠 Suggested Commands

# Backend (Bun + Express)
cd apps/backend
bun install
bun dev

# Frontend (Bun + Vite)
cd apps/frontend
bun install
bun dev

# Run Tests
bun test

# Start Full Infra (Dev)
docker-compose up -d