How RHPAM supports communication between process deployed on different spring boot embedded kie server

We have a use case where we have processA deployed on kieServerA and it needs to invoke processB which is deployed on different kieServerB.

Kie server exposed rest APIs can be an invocation approach, but processB is a long-running process and we don't want the REST connection to remain open for long, which would consume all TCP connections.
What are other ways of asynchronous communication between processes deployed on different servers and how can we achieve them?

Please assist.