Software architectural style for adding new components/modules

I am looking for suggestions on which architectural style to choose which is well suited to handle the problem of adding new components/modules. I looked at component based architecture. But unsure about concrete implementation(design patterns to use) that how other parts of system(which are interested in performing tasks) will know when new modules available for same task. For example: A system can do Task A and Task B. For doing Task A there are 3 modules and for Task B 4. User wants to add a new module for Task A. Or user wants to remove some module for Task B.

Kindly guide me in right direction.