Publishing an event to Kafka puts it “out there” in a way that guarantees it won’t be lost and allows any number of interested consumers, including the data warehouse, to deal with it at their leisure (subject to retention period which is typically like 72h). For us, your Kafka topics and their schemas are as much a part of your API as your gRPC IDLs. Something like Redis or 0MQ feels more appropriate for internal coordination between instances of the same service, or at least a producer that has a specific consumer in mind.