This article was written and published 2020–01–07 on my personal blog, this is a repost

The problem

Let’s say that you’re developing a software in a monolithic approach and you need to create a new functionality. What you will probably do is to search or define a new “business identity” and from there create what you need. If you need to expose something, you will create appropriate APIs, and if you need something from somewhere else, you will just call that method on that class.