Domain-Driven Design techniques and principles give us guidance on how to model and build software. The challenge is - how to apply them when replacing systems that already exist? It turns out that Strategic patterns can help you learn about existing solutions and reasons why change is needed. The Tactical ones can be applied to build software that will make implementation of new capabilities possible. It all sounds good in theory, but how to do it in practice?

In this talk Kacper will take you on a journey during which he will reflect on his experience with replacing a complex loyalty system and challenges the project faced. He will share with the audience his thoughts on what worked, what could have been done differently and what caused problems. You will learn how to make best use of Domain Experts and explain why consistency is a business problem. Try to answer if it’s possible to stay sane in the Microservice world and discuss challenges arising when trying to migrate from CRUD persistence to Event Sourcing.