:+1: here.

Some notes:

• odcs uses rhmsg for "this" (really amqp).
• freshmaker does the same as odcs (I think). It is worth checking.
• MBS grew a plugin system that allowed us write https://github.com/release-engineering/mbs-messaging-umb

When waiverdb and greenwave grow support for non-fedmsg messaging, I guess it would be nice if they copied either odcs/freshmaker or MBS so that we're left with only two ways of doing this instead of three of four.

Updated the issue to mention AMQP also. Doesn't really matter whether we go with STOMP or AMQP for the protocol since our internal message broker supports both. Just use whatever is easier to integrate, I guess.