To be able to consume events in the core services, we need to do the following:

Declare message processors that listen for events on its topic.

Change our service implementations so it uses the reactive persistence layer correctly.

Add configuration for consuming events.

Change our tests so that they can test the asynchronous processing of the events. 

https://learn.microsoft.com/en-us/dotnet/architecture/microservices/multi-container-microservice-net-applications/integration-event-based-microservice-communications