Event streaming is not a new concept. Coroutines are also not a new concept. However, these two concepts, together, are only now being widely used and considered for new developments and updates of old applications. Kotlin provides a way to implement applications in a reactive way using coroutines, and implementing event streams. We will have a look at different running application examples and how they can respond to event triggers, how they can digest event messages and how that plays out in terms of performance. We will also draw a few comparisons to understand how a reactive architecture works.