The way it's been explained to me. A pub/sub relationship should convey metadata of state change. Any state change in the system should be communicated via pub

The way it's been explained to me. A pub/sub relationship should convey metadata of state change. Any state change in the system should be communicated via pub/sub. A subscriber might need to use a request/response interaction with some other microservice in order to act on a pub/sub, but that's not a state change, that's just auxiliary data needed to do its job that is triggered on a state change.