order-processing-system

A set of microservices designed to implement the order and payment processing system.

Getting Started

These instructions will get you a working API that you can interact with.

Prerequisites

What things you need to run the system and how to install them

• node.js
• npm (will be automatically installed with node)
• docker
• docker-compose
• insomnia

Starting the services

To launch the set of services, just run the following:

docker-compose up

If you want to run the services in the background then add the -d flag

docker-compose up -d

In order to rebuild the services add the --build flag at the end

docker-compose up --build

or

docker-compose build

Access the API

To access the API you can send out curl requests to http://localhost:8000/api or better, open Insomnia Rest Client and import the collection provided insomnia_collection.json to view the complete set of routes with sample body provided.

Architecture

The overall architecture includes two node.js applications, a messaging broker, a gateway and a database service. The entire application is brought up with docker-compose as a proof of concept which can be replaced with a simple kubernetes cluster.

Here is a diagramatic overview of the system:

Authentication

Authentication middleware has been placed as a dummy that always returns appends a user's details in the request object. A string/token has been hardcoded to protect all routes that needs to be passed in the request authorization header. This mocks an already signed in user behavior where a signed in session will automatically be sending a JWT token for example, in the authorization header.

To make the application work please add this hardcoded token in the request header:

Authorization: thisisajwttoken

Orders API

A user is allowed to create an order, cancel an order, get a specific order or get all their orders.

Routes

• GET /api/orders - gets all the orders for the user
• POST /api/orders - creates an order against the user
• GET /api/orders/{id} - gets a specific order for the user
• DELETE /api/orders/{id} - cancels a specific order for the user

Sample body for order creation:

{
	"bill": 2000
}

The provided Insomnia collection has all the routes provided with prefilled request body, headers etc.

Events Pushed to Messaging Broker

• payment-create-event - pushed to the broker whenever an order is created so that a corresponding payment object is created

Events Received from Messaging Broker

• payment-processed-event - received whenever a payment is processed. Can be a denied payment or an accepted payment. Based on the status the appropriate event handler is invoked

Cron Job

• Whenever an order is confirmed, a timer is added to the callback queue to process the order and change the status to delivered after a hardcoded time.

Payments API

A user can get a specific payment using the order ID or can get all their payments as well as initiate a payment for a specific order.

• GET /api/payments - gets all the payments for the user
• GET /api/payments/{orderId} - gets a specific payment against an order for the user
• POST /api/payments/pay/{orderId} - initiates a payment against an order for the user.

A sample body for the last route is provided as below:

{
	"creditCardDetails": {
		"number": "10298310928301",
		"cvt": 345,
		"expiry": "4/12/2020"
	}
}

The provided Insomnia collection has all the routes provided with prefilled request body, headers etc.

Events Pushed to Messaging Broker

• payment-processed-event - pushed whenever a payment is processed. Can be a denied payment or an accepted payment.

Events Received from Messaging Broker

• payment-create-event - received whenever an order is created so that a corresponding payment object is created

Testing

In order to run the unit tests, go to either of the apps folders orders-api/ or payments-api/ and run the command:

npm run test

Built With

• Express - Fast, unopinionated, minimalist web framework for Node.js

Authors

• Hassaan Pasha - website

Acknowledgments

• PurpleBooth for the awesome README template