Order Service manages the lifecycle of orders within the MicroServiceGrid system-DDD and is a microservice responsible for managing orders in an e-commerce system.
This is the updated Saga version, replacing the legacy CRUD approach.
You can find the legacy CRUD version here: Legacy CRUD Version

The service supports pagination, sorting, and filtering by status or user email. It is part of MicroserviceGrid project and communicates with other services and infrastructure as follows:

• Order management: create, update, cancel, and fetch orders.
• Saga orchestration using Kafka for reliable business processes:
  • Inventory confirmation
  • Payment processing
• Outbox pattern for reliable Kafka event publishing.
• Validation via @Valid annotations.
• Custom exceptions and global handling (OrderNotFoundException, ProductOutOfStockException, etc.).

• Java 21
• Spring Boot 3
• Spring Data JPA
• Kafka (Spring Kafka)
• MySQL (Flyway migrations)
• Lombok
• Avro for event serialization

The service listens to the following topics:

Events are published using Outbox, processed by a Kafka Worker.

Base URL: /api/v1/orders

POST /api/v1/orders
Content-Type: application/json

{
"userDetails": {
  "email": "[email protected]",
  "name": "Andrii"
},
"items": [
  { "productId": "123", "quantity": 2 }
]
}

Response: 201 Created

GET /api/v1/orders/{orderNumber}

Response: 200 OK

GET /api/v1/orders?page=0&size=10&sort=createdAt,desc&status=CREATED&[email protected]

PUT /api/v1/orders/{orderNumber}
Content-Type: application/json

PATCH /api/v1/orders/{orderNumber}/cancel

  src/main/java/com/akul/microservices/order
  ├─ controller   # REST endpoints
  ├─ application  # DTOs and services
  ├─ domain       # Models, OrderStatus, Exceptions
  ├─ event        # Events (PaymentRequestedEvent)
  ├─ infrastructure
  │   ├─ messaging/kafka  # Kafka Listeners & Topic Resolver
  │   ├─ outbox           # Outbox pattern
  │   ├─ persistence      # JPA repositories
  │   └─ worker           # Outbox Publisher
  └─ resources
  ├─ db/migration     # Flyway SQL migrations
  └─ application*.properties

     User
      │
      ▼
     Order Service
      │
      ├── validate order
      ├── persist order in DB
      ├── save ORDER_CREATED event to Outbox
      │
      ▼
     Outbox Worker → Kafka
      │
      ▼
     Inventory Service
      ├── check stock
      ├── reserve inventory (per SKU)
      ├── create reservation (TTL)
      ├── save INVENTORY_CONFIRMED / INVENTORY_REJECTED / INVENTORY_EXPIRED to Outbox
      │
      ▼
     Outbox Worker → Kafka
      │
      ▼
     Order Service reacts
      ├── CONFIRMED → publish PAYMENT_REQUESTED
      └── REJECTED / EXPIRED → mark order as FAILED
      │
      ▼
     Payment Service
      ├── process payment
      ├── save PAYMENT_COMPLETED / PAYMENT_FAILED to Outbox
      │
      ▼
     Outbox Worker → Kafka
      │
      ▼
     Order Service updates order status
      ├── PAYMENT_COMPLETED → COMPLETED
      └── PAYMENT_FAILED → FAILED + INVENTORY_CANCELLED

Scheduler
│
├── find expired reservations
├── mark EXPIRED
├── release inventory
├── save INVENTORY_EXPIRED to Outbox
▼
Kafka → Order Service
│
└── update order as FAILED

🧠 Key Design Principles

• Outbox pattern ensures reliable event delivery
• Idempotent operations via (order_id, sku_code) uniqueness
• TTL reservations prevent stock locking
• No distributed transactions — each service updates its state based on events
• Multi-SKU orders processed independently

PENDING
├─> INVENTORY_RESERVED
│    ├─> PAYMENT_PROCESSING
│    │    ├─> PAID
│    │    └─> FAILED
├─> FAILED
└─> CANCELLED

• Create orders via REST API
• Confirm or reject orders through Saga
• Automatic status updates
• Outbox + Kafka for guaranteed event delivery
• Idempotent handling to avoid duplication

Example:

POST /api/v1/orders
Content-Type: application/json

  {
  "items": [
  { "sku": "iPhone-15", "productName": "iPhone 15", "price": 1500.0, "quantity": 1 }
  ],
  "userDetails": {
  "email": "[email protected]",
  "firstName": "Test",
  "lastName": "User"
  }
  }

• Integration tests via Testcontainers (Kafka + MySQL)
• Verify Saga flow: CREATE → INVENTORY_CONFIRMED → PAYMENT → ORDER_COMPLETED
• Idempotency, Outbox, and TTL handling

git clone https://github.com/Andrij72/order-service.git
cd order-service
docker-compose -f docker-compose.local.yml up -d
./mvnw spring-boot:run

• Inventory insufficient → INVENTORY_REJECTED → order CANCELLED
• Reservation TTL expired → INVENTORY_EXPIRED → order CANCELLED
• Payment failed → PAYMENT_FAILED → compensation: INVENTORY_CANCELLED

Andrii Kulynch Microservices, Kafka, Saga, Outbox, Spring Boot 📅 Version: 3.0