In the last 5 years, we have not seen such a sophisticated and fast evolution of technology as the one Kotlin is going through. Such a speed in evolution can lead us sometimes to think that Kotlin can do anything including replacing external event streaming / queueing systems such as Kafka and RabbitMQ. In real life, this remains something that we must decide by considering what we want to implement. In this session, we'll have a look at the pitfalls of event streaming using pure Kotlin code, where this can be used, and when we definitely need to use an external event streaming system.