Welcome to the Beacon Podcast by ThoughtWorks. Today's episode explores evolutionary architecture. Let's get started.

Hello, my name is Newell Ford. I'm a director, software architect, and meme wrangler at ThoughtWorks.

And today I'm with Rebecca Parsons.

And I'm Rebecca Parsons, Chief Technology Officer for ThoughtWorks and Geek Wrangler.

And we are together with our colleague Pat Kwaa writing a book about the subject of evolutionary

architectures and software.

And today we're going to talk about one particular aspect of our definition of evolutionary

architecture.

So here's our working definition right now.

Evolutionary architecture support incremental guided change as a first principle across multiple dimensions.

That's our working definition for evolutionary architecture.

And we've talked about some of the aspects of the definition on other podcasts. Today, we're going to focus

on the guided part of our definition, and in particular this idea around fitness functions.

And when we talk about a fitness function, this is really our way of characterizing about

an architecture or about a system, what we want out of that

architecture. So when we talk about software design, you very often hear the phrase emergent

design. And we're not talking about emergent architecture. We're talking about evolutionary

architecture. That guided aspect is where we get the

connection for guided and evolutionary, that there is, in fact, something other than just

ad hoc change that is being talked about here. We are looking instead at how we move a system,

how we move an architecture towards a particular goal.

And so this is this notion of evolutionary change.

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