Hexagonal (Ports and Adapters)

In 2005, Alistair Cockburn published an article on his website describing an architectural pattern he had been thinking about for years. He called it hexagonal architecture.

Cockburn said the number six has no meaning. The hexagon simply gave him room to draw many ports around the edge of the application, and it broke the habit of drawing an application as a vertical stack of layers.

The idea in the post was this: stop thinking about software as a stack with a top and a bottom. Stop thinking about the database as the foundation and the UI as the surface