architecture – How to design a real-time order delay tracking system for an ecommerce site?


I could not solve this architecture puzzle, thus asking here now. The use case says that we want to build a system that can track millions of orders in near real time if there is any delay anywhere?

Once an order is received, with event based, possibly via kafka-streams and Microservices we can orchestrate the order to different services for processing but how to we track that if all of them are getting processed on time or not. I answered this thinking of a scheduled job that can run after every hour but was told that think you need real time tracking and there are millions of orders.