This post is part of The Software Architecture Chronicles, a series of posts about Software Architecture. In them, I write about what I’ve learned on Software Architecture, how I think of it, and how I use that knowledge. The contents of this post might make more sense if you read the previous posts in this series.
The Onion Architecture was coined by Jeffrey Palermo in 2008. As I see it, it builds on the Ports & Adapters Architecture by adhering to the idea of placing the domain in the centre of the application, externalising the delivery mechanisms (UI) and infrastructure used by the system (ORM, Search engines, 3rd party APIs, …). But it goes further and adds internal layers to it.