“Embrace Change”, says eXtreme Programming. Avoid big upfront design they say. What it means is to start experimenting with the knowledge we have at the time. To choose a potential solution (to a specific opportunity), and start running experiments towards it.

When we do this, we very likely will learn that our initial assumptions were not 100% accurate. We might see that:

- some parts of the codebase is suboptimal,
- database structure is not supporting us the way we would wish, or
- we are sending wrong data in our events / commands.

No worries, because in the end, we need to live in the changing world - with evolving codebase. And if we live this assumption, we better learn how to:

- do evolutionary design without breaking changes in production.
- change the internal structure bit by bit in a way that every change is deployable with no breaking changes and
- to do all above with not introducing bugs.

In this talk, Aki will introduce possible strategies he has used in his projects for such changes. Making gradual evolutionary design changes that never break production. He comes to share his insights with the hope the audience would be inspired and see that 'I can do it, too!'

first public delivery, and contains real code examples, supported with drawings and visuals