In this blog, I want to speak about the book Building Evolutionary Architectures by Neal Ford, Rebecca Parsons, and Patrick Kua. I have attended Neal's conference talk on this topic and heard from many other speakers about the fitness functions. That’s the reason I wanted to read and understand the concepts mentioned in the book.
As the title implies, the book talks about building evolutionary architecture. The question that the book trying to solve is, how do we make sure, our software architecture stays intact with the changing requirements? How do we build the system which can adapt to future needs or how do we know the decision that we are taking is not impacting the architecture of the system?
The book speaks about fitness functions, to solve this concern. An architectural fitness function provides an objective integrity assessment of some architectural characteristics. So, in a system there may be many characteristics that we want to measure, so you would write separate fitness functions for each of them. In the book, a fitness function is not defined in a concrete way but rather in an abstract form of graphs, tests or any other methods by which we know that our system is doing good with the change. This means you would still need to use your intellect not only to write the fitness function but also to make sense of them.
For me, the best thing about the book is, it provides software architects with a rich vocabulary to communicate their intentions behind their choices to a variety of audiences, including business stakeholders, teams, and engineering leadership. The book also gives you a survey of various architectural approaches. It also talks about some of the practical ideas on how do we implement evolutionary architectures I particularly like the focus on the organizational factors and how does it apply to the software architectures.
In conclusion, I would recommend this book to any software architect. Use it as your communication guide, use it to improve your vocabulary, use it to get a sense of what is happening across the industry, so that you could choose what best for your situation.