Domain-Driven Rails Redux

Over the last 5 years, Rails apps have increased in size, complexity, and value provided to businesses. A few years back all we had to do was customize some generated code and sprinkle on a bit of AJAX, and the rapid pace of development meant that we could launch products and add features way faster than our competitors could. Nowadays, top Rails developers are charged with maintaining systems that generate millions of dollars of revenue, understanding complex domains, and integrating with partner systems. This new job description requires a shift in perspective from the “build a blog in 5 minutes” approach to Rails.

In this talk, I will continue my exploration of Domain-Driven Design as it applies to Rails development. After a brief discussion of the kinds of complexity found in Rails apps, I’ll show how Aggregates and Bounded Contexts can help manage that complexity. I’ll demonstrate techniques for treating ActiveRecord structures as aggregates, and how to decouple one aggregate from another. I’ll show you when you should start looking for different BCs, how to identify them, and how to begin carving them out. We’ll also look at how some of the new features from Rails 3, such as mountable apps, can be used to build modularity into a complex system.

If you’re a serious Rails practitioner, you should come to this talk. It’s my goal to make this one of the best talks at this or any other Rails conference. Problems that you may have that I aim to solve:

• Code that is difficult to understand
• Code that is resistant to change
• Slow-running test suites
• Knowledge silos

Most of all, this talk is about recognizing and managing the complexity within your app. In valuable applications, complexity is unavoidable. How we choose to manage it is up to us. If you don’t spend the time and effort to control it, it will control you.