Part 2. The code

Our ecosystem is done! We’ve come a long way and, more importantly, significantly increased our confidence for what lies ahead. And what lies ahead is the subject of part 2.

We now shift our focus to the actual code of your application. Over the next few chapters, we’ll discuss many ways you can effect change in your code to make it more maintainable and easier to change. We won’t provide an exhaustive list of all the changes you could possibly make. But we’ll focus on topics that, in our experience, will give you a lot of bang for your buck in a brownfield application.

We’ll start by getting back to the basics in chapter 7. Here, we’ll review what it means to be object oriented and get you in the right frame of mind for future changes. We’ll go over some common principles that will be the basis for many of the code changes in the subsequent chapters.

Chapter 8 builds on this foundation by looking at how to layer (or, more likely, relayer) the application. Our work on automated unit tests will bear some fruit as we discuss how to use these tests to isolate the layers in our applications.

Chapter 9, “Loosen up: Taming your dependencies” will be an interesting topic. Here we’ll look at how to tease apart the dependencies of your classes to reduce your coupling and increase the maintainability of your code.

In chapter 10, we’ll look at patterns for the user interface, specifically Model-View-Controller and Model-View-Presenter, and how best to take advantage of them in a brownfield application.

Chapter 11 is at the other end of the application. Here, we’ll move to the data access layer. You’ll see strategies on refactoring your data access, including how an object-relational mapper can abstract away the database and provide you with a reusable and testable data access strategy that’s receptive to change.

In chapter 12, we delve into integration territory. We talk about how to work with external systems and how we can manage our interfaces with them to reduce our exposure in the event they change.

Finally, in lucky chapter 13, we close with some encouragement on how to keep the momentum going to ensure the project doesn’t lapse back into brownfield contamination.