As a result, we now have five microservices catering to the checkout process:

ShoppingCartApi – Exposes the /checkout endpoint to UI client and triggers checkout process

StockValidatorService – Validates the availability of stocks for all the line items

TaxCalculatorService – Calculates the tax based online items and customer address

PaymentProcessingService – Processes the payment based on the credit card details, line items, and calculated tax

ReceptGeneratorService – Generates and saves the receipt for the purchase. Also, responsible for email communication with the customer

https://code-maze.com/long-running-tasks-microservices/