Event sourcing persists each entity as a sequence of state changing events. An entity’s current state is derived by replaying those events. Event sourcing is a great way to implement event-driven microservices. When one service updates an entity, the new events are consumed by other services, which then update their own state.
In this talk we describe how to implement business logic using event sourcing. You will learn how to write functional, immutable domain models in Scala. We will compare and contrast a hybrid OO/FP design with a purely functional approach.