https://reflectoring.io/book/

A good software architecture should keep the cost of development low over the complete lifetime of an application.

Ever wondered about how to actually implement a “Clean Architecture” or a “Hexagonal Architecture”? There’s a lot of noise around these keywords, but you can find very little hands-on material on this topic.

This book fills a void by providing a hands-on approach to the Hexagonal architecture style from the concepts behind it down to actual code.

All About Hexagonal Architecture

Get a Grip on Your Layers