Paul Jones has a new post to his site today with a more in-depth look at his proposed "Action-Domain-Responder" design pattern and how to refactor an application, based on some with with the Aura framework, to use it.
The v1 version of the Aura framework includes a controller to handle web assets. The idea for this controller was that an Aura package might have images, scripts, and stylesheets that need to be publicly available, but in development you don’t necessarily want to copy them to a public document root every time you change them. [...] That v1 version is a mess. The Controller handles the response-building entirely, and there is no Model separation at all. Let’s try refactoring it to an Action-Domain-Responder architecture and clean it up some for a v2 version.
Associated code it just linked to, but he does summarize the steps needed to make the transition: extract the domain logic, move responses to a separate class and rename the controller to an action. He also shows how making this separation makes testing easier and links to examples of tests for each. He finishes the post with two final notes about the refactor. One points out that this method isn't the only way to handle this architecture shift and that the action returns a responder, not a response object.