Event Sourcing and CQRS are two popular patterns for implementing a Microservices architectures. With Event Sourcing we do not store the state of an object, but instead store all the events impacting its state. Then to retrieve an object state, we have to read the different events related to a certain object and apply them one by one. CQRS (Command Query Responsibility Segregation) on the other hand is a way to dissociate writes (Command) and reads (Query). Event Sourcing and CQRS are frequently grouped and used together to form something bigger. While it is possible to implement CQRS without Event Sourcing, the opposite is not necessarily correct. In order to implement Event Sourcing, an efficient Event Store is needed. But is that also true when combining Event Sourcing and CQRS? And what is an event store in the first place and what features should it implement?
This presentation will first discuss what functionalities an event store should offer and then present how Apache Kafka can be used to implement an event store. But is Kafka good enough or do specific event store solutions such as AxonDB or Event Store provide a better solution?