E-commerce Microservices — Inventory & Order

This repository contains two Spring Boot microservices demonstrating a simple e-commerce flow:

• inventory-service (port 8081)
• order-service (port 8082)

This README documents the available REST APIs (URLs, request/response examples) and quick run / debug instructions.

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Quick Start

From the repository root you can run both services with Maven (two shells or single command):

PowerShell (single command):

mvn -pl inventory-service,order-service -am spring-boot:run

Or run each module separately (two terminals):

# Inventory service
mvn -pl inventory-service -am spring-boot:run

# Order service
mvn -pl order-service -am spring-boot:run

Both services use in-memory H2 databases and Liquibase changelogs to load schema + sample CSV data at startup.

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Inventory Service (port 8081)

Base URL: http://localhost:8081

H2 Console: http://localhost:8081/h2-console

• JDBC URL: jdbc:h2:mem:inventorydb
• Username: sa (password empty)

Liquibase changelogs: inventory-service/src/main/resources/db/changelog/

• changelog-001-create-tables.xml (creates table product_batch)
• changelog-002-data-load.xml (loads inventory.csv)
• CSV: inventory-service/src/main/resources/db/changelog/data/inventory.csv (sample batches)

Endpoints

1. GET /inventory/{productId}

• Description: Returns product information and a list of batches sorted by expiry date (ascending).
• URL example: GET http://localhost:8081/inventory/1001
• Response (example):

{
  "productId": 1001,
  "productName": "Laptop",
  "batches": [
    { "batchId": 1, "quantity": 68, "expiryDate": "2026-06-25" }
    // ...
  ]
}

PowerShell example:

Invoke-RestMethod -Method Get -Uri http://localhost:8081/inventory/1001

curl example:

curl -X GET http://localhost:8081/inventory/1001

2. POST /inventory/update

• Description: Reserve / decrement inventory quantity across batches (FEFO / earliest expiry first). Returns reservation result and batch ids used.
• URL: POST http://localhost:8081/inventory/update
• Request body (JSON):

{
  "productId": 1002,
  "quantity": 3
}

• Successful response (example):

{
  "success": true,
  "message": "Reserved",
  "reservedFromBatchIds": [10]
}

PowerShell example:

$body = @{ productId = 1002; quantity = 3 } | ConvertTo-Json
Invoke-RestMethod -Method Post -Uri http://localhost:8081/inventory/update -Body $body -ContentType 'application/json'

curl example:

curl -X POST -H "Content-Type: application/json" -d '{"productId":1002,"quantity":3}' http://localhost:8081/inventory/update

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Order Service (port 8082)

Base URL: http://localhost:8082

H2 Console: http://localhost:8082/h2-console

• JDBC URL: jdbc:h2:mem:orderdb
• Username: sa (password empty)

Liquibase changelogs: order-service/src/main/resources/db/changelog/

• changelog-001-create-tables.xml (creates orders table)
• changelog-005-reload-orders.xml (loads sample orders CSV in a dev-friendly way)
• CSV: order-service/src/main/resources/db/changelog/data/orders.csv

Configuration

• Order service reads the inventory base URL from application.yml:

inventory:
  service:
    url: http://localhost:8081

Change this if your inventory service runs on a different host/port.

Endpoints

1. POST /order

• Description: Places an order. The Order service first queries Inventory service for batches, then calls Inventory service to reserve inventory, and finally stores the order.
• URL: POST http://localhost:8082/order
• Request body (JSON):

{
  "productId": 1002,
  "quantity": 3
}

• Successful response (example):

{
  "orderId": 1000,
  "productId": 1002,
  "productName": "Smartphone",
  "quantity": 3,
  "status": "PLACED",
  "reservedFromBatchIds": [9],
  "message": "Order placed. Inventory reserved."
}

PowerShell example:

$body = @{ productId = 1002; quantity = 3 } | ConvertTo-Json
Invoke-RestMethod -Method Post -Uri http://localhost:8082/order -Body $body -ContentType 'application/json'

curl example:

curl -X POST -H "Content-Type: application/json" -d '{"productId":1002,"quantity":3}' http://localhost:8082/order

Notes: the response includes reservedFromBatchIds (batches where inventory was deducted) and a human message.

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Development / Debugging Tips

• If Liquibase has already applied a changeSet in a persistent DB, changing the changeSet file will not re-apply it. For development with in-memory H2 the DB is recreated on each restart so changes to changelogs / CSV will take effect when you restart the app.

• H2 Console connections (for each service):

  • Inventory: JDBC URL jdbc:h2:mem:inventorydb
  • Orders: JDBC URL jdbc:h2:mem:orderdb
  • User: sa, password empty

• Default ports: Inventory 8081, Order 8082. If you change ports, update the inventory.service.url property in the Order service application.yml.

• Factory pattern: Inventory reservation logic is implemented via InventoryHandler interface and a DefaultInventoryHandler bean; the InventoryHandlerFactory picks handler beans by name.

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Where to look in the code

• Inventory service

  • Controllers: inventory-service/src/main/java/com/ecommerce/inventory/controller/InventoryController.java
  • Service: inventory-service/src/main/java/com/ecommerce/inventory/service/InventoryServiceImpl.java
  • Repository: inventory-service/src/main/java/com/ecommerce/inventory/repository/ProductBatchRepository.java
  • Factory/handlers: inventory-service/src/main/java/com/ecommerce/inventory/factory/
  • Liquibase & sample data: inventory-service/src/main/resources/db/changelog/

• Order service

  • Controller: order-service/src/main/java/com/ecommerce/order/controller/OrderController.java
  • Service: order-service/src/main/java/com/ecommerce/order/service/OrderServiceImpl.java
  • Repository / entity: order-service/src/main/java/com/ecommerce/order/repository/ and .../model/OrderEntity.java
  • Liquibase & sample data: order-service/src/main/resources/db/changelog/

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If you want, I can also:

• Add OpenAPI/Swagger UI for both services;
• Add unit and integration test scaffolding (recommended for the assignment requirements);
• Add a small README per-module (inventory-service/ORDER-service) with focused examples.

Which of those would you like next?