Hello,
suppose we have an event in a context that needs to be denormalized and sent over a RabbitMQ queue where another context is listening.
When the queue message is received from the other context, it applies a new command/event chain and everything goes fine.
After a while, another different context from the two above needs to receive the same event. Nothing simpler, i will add another eventhandler that writes the event on the queue listened by the new context.
At this point, I replay all the events in event store. Due to rabbitmq eventhandlers is excluded from the ones managed by the replay cluster, the command/event chain on the other context never happens to start.
I do not think that upcasters are useful in this case because they act as a “decorator” over an existing event.
The most obvious solutions seems to include the rabbitmq eventhandlers in the replay cluster, but this will double the events when I replay the event stream.
Another solution is to write a batch that sends the “missing” commands but i hope this is not the final answer because it sucks.
Any idea? Hope someone helps. 
Samuele