Support multiple server instances communicating with each other in HA setup

[rahul1995]

The problem I am facing
For some reason, I would want to close all the connections for a particular document.
My other microservice will call Collaboration server to close all the connections.
In HA setup, there will be multiple server instances. But the call will come to only one server instance.
It can close the connections made on this server, but this message needs to be broadcasted to all the server instances.

The solution I would like
Currently "extension-redis" supports message passing from client -> server and server -> all client instances.
But there is no way for server to "tell" other server to perform something at the server.
The handleIncomingMessage is also non-extendable so that a custom strategy could be hooked in. Also, MessageReceiver's apply method is also non-extendable and can only support the MessageTypes coming OOTB. So, I cannot find any easy way to extend the functionality.

Alternatives I have considered
Currently, thinking of writing a custom extension similar to extension-redis with some change in behaviour of handleIncomingMessage(). Not tried yet.

Additional context
Add any other context or screenshots here.

[rahul1995]

Alternative I am using right now - I extended Redis-extension class and created two more pub, sub redis clients to publish/listen server-to-server messages.