K8 Coffee Shop Overview

Goal:
This application simulates the process of ordering coffee. The Order Service handles customer orders, while the Inventory Service manages stock availability. When a customer places an order, the Order Service checks with the Inventory Service to confirm if the requested coffee ingredients are in stock.

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Architecture

1. Service 1: Order Service

   • Purpose: Manages customer orders.
   • Responsibilities:
     • Accepts new coffee orders via API.
     • Communicates with the Inventory Service to verify availability.
     • If ingredients are available, confirms the order.
     • If ingredients are out of stock, suggests an alternative coffee or informs the user.

   Sample Endpoints:

   • GET /order – Place a new order.

   Example Request:

   
   GET /order/place?coffeeType=cappuccino&quantity=1
   
   

   Example Response:

   {
    "coffeeType": "cappuccino",
    "quantity": 1,
    "status": "Confirmed"
   }
   
   

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2. Service 2: Inventory Service

   • Purpose: Manages stock for ingredients (e.g., coffee beans, milk, syrups).
   • Responsibilities:
     • Checks if the required ingredients are available for a given coffee type.
     • Updates stock levels after a successful order.
     • Provides available coffee alternatives when stock is insufficient.

   Sample Endpoints:

   • GET /inventory/stock – Returns the available stock of all the ingredients.
   • POST /inventory/used – Reduce the stock of the specify ingredients.

   Example Response (GET /inventory/stock):

   {
    "espressoShot": {
      "name": "Espresso Shot",
      "quantity": 10
    },
    "milk": {
      "name": "Milk",
      "quantity": 1000
    },
    "hotWater": {
      "name": "Hot Water",
      "quantity": 99999999
    },
    "milkFoam": {
      "name": "Milk Foam",
      "quantity": 500
    }
  }

Example Request (POST /inventory/used):

{
  "espressoShot": 1,
  "milk": 200,
  "milkFoam" : 50
}

Example Response:

true/false

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Communication Flow

1. Customer places an order by sending a request to the Order Service.
2. Order Service calls Inventory Service to check stock availability.
3. If the stock is available, Order Service confirms the order.
4. If the stock is unavailable, Order Service responds with suggested alternatives or an out-of-stock message.

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Workflow Example

1. Customer:

   • “I want a Large Cappuccino.”

2. Order Service:

   • Checks with Inventory Service:
     • “Do we have ingredients for Large Cappuccino?”

3. Inventory Service:

   • Responds:
     • “Milk is out of stock. Suggested alternatives: Espresso, Americano.”

4. Order Service:

   • Sends a response to the customer:
     • “Cappuccino is unavailable. Would you like an Espresso or Americano instead?”

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How to run the services

1. Check version of npm : npm -v
2. Check version of node : node -v
3. Set / Export required variables in environment ( Use env file or set / export variables ) Positive numerical values can be set for the following environment variables to override default values : ESPRESSO_SHOT_QUANTITY MILK_QUANTITY HOT_WATER_QUANTITY MILK_FOAM_QUANTITY
4. cd inventory-service
5. npm install
6. npm run build
7. Inventory service url should be set in INVENTORY_URL environment variable. Default value is http://localhost:3000
8. In separate terminal : cd order-service
9. npm install
10. npm run build

Technology Stack

• Backend:
  • NestJS
• API Communication:
  • REST or gRPC for service-to-service communication.