WebApp - session context, threads & class interfaces

Im trying to come up with a unified method for communicating feedback to session users/observers of the application.

I have an app that kicks off a thread that does some rest communications with a couple of apis. It runs and does whats expected pretty well, so now Im trying to figure out the ui. The thread contains a number of classes that interact wit the apis, timing cycles and so on. I *think I want to create a class that contains the framework for communicating activity back up the event/ui chain so that the interface can be implimented by any class embedded in the thread. The class would contain the mechanics to deal with the context. Im a bit confused about how a number of users/observers would attach to and view the activity. How does one make ui data available to more than one session?

Are those reasonable design thoughts?