Communicating across multiple contexts in Axon is currently unintuitive. I have struggled to find anything in the reference guide and the offered APIs are not very explicit. Since communication between multiple bounded contexts is a central concept in DDD I feel like it should be supported better.
I created two threads (Thread 1, Thread 2) on this issue and the answers helped me solve my problem. I added some thoughts on how I would imagine the API. Maybe it has some place in Axon 5. Anyways, I hope I can spark a conversation in your team on this topic.
PS: Any best practices regarding communication between contexts in Axon are more than welcome. I am still experimenting with this and I am looking for design guidelines.