The AngularAndSpring project uses Kafka for the distributed sign-in of new users and the distributed token revocation for logged-out users.
The AngularAndSpring project needs to be able to be horizontally scaled each with its own database. To enable that, a sign-in needs to be propagated to all instances. Kafka serves as a central event streaming platform to send the sign-in events. Kafka is horizontally scalable to high event loads and can be set up to be highly available.