Building Microservices: Designing Fine-Grained Systems

by Sam Newman

Loose Coupling When services are loosely coupled, a change to one service should not require a change to another. The whole point of a microservice is being able to make a change to one service and deploy it, without needing to change any other part of the system. This is really quite important. What sort of things cause tight coupling? A classic mistake is to pick an integration style that tightly binds one service to another, causing changes inside the service to require a change to consumers. We’ll discuss how to avoid this in more depth in Chapter 4. A loosely coupled service knows as little as it needs to about the services with which it collaborates. This also means we probably want to limit the number of different types of calls from one service to another, because beyond the potential performance problem, chatty communication can lead to tight coupling.

MS is loosely coupled