The Solution To BDUF Isn’t Faster BDUF

Big Design Up-Front – making lots of design decisions before getting real-world feedback on any of them – fails at any speed of decision-making. Indeed, the faster we make design decisions, the more we tend to fail. Most folks make a category error of approaching design as a shopping list of decisions. We decide A, B, C, D. If it turns out B is wrong, we can just change B. But it’s not a list – it’s a tree. Each decision constrains future choices. If B is wrong, C and D may well be wrong, too, if they’re consequences of B. And we might also make the mistake of thinking we can just unpick the decision tree, but it’s not as simple as that. First of all, we have to distinguish the leaves from the nodes. What is the root decision that we got wrong. And all we see in the resulting code is leaves. Also, dependencies between decisions don’t operate like dependencies in code. So we’d have to extract an entire branch of decisions from an orthogonally-interconnected architecture. Decision X, Y…