The SitePoint PHP blog has kicked off a new series of posts today with the first tutorial about building an application with OOP and the Slim framework. In this starting article they focus in on bootstrapping the application and introducing some of the basics behind MVC and OOP.

At a certain point of my development as a PHP programmer, I was building MVC applications by-the-book, without understanding the ins-and-outs. I did what I was told: fat model, thin controller. Don’t put logic in your views. What I didn’t understand was how to create a cohesive application structure that allowed me to express my business ideas as maintainable code, nor did I understand how to really separate my concerns into tight layers without leaking low-level logic into higher layers. I’d heard about SOLID principles, but applying them to a web app was a mystery. In this series, we’ll build a quiz application using these concepts. We’ll separate the application into layers, allowing us to substitute components: for example, it’ll be a breeze to switch from MongoDB to MySQL, or from a web interface to a command-line interface.

They start off with a bit about why "MVC is not enough" and how they'll be applying domain modeling as a part of the application. There's also a brief mention of the concept of a service layer and how it will fit into the overall structure. Then it's on to the code: getting Slim installed (via Composer) and starting in on the interface/service classes for the Quiz. They walk you through entity creation for the Quiz and Question instances and a mapper to tie them together.