ALTER-SYSTEM-ADD-FOLLOWER ALTER-SYSTEM-ADD-OBSERVER ALTER-SYSTEM-ADD-BACKEND ALTER-SYSTEM-ADD-BROKER ALTER-SYSTEM-MODIFY-BACKEND ALTER-SYSTEM-DECOMMISSION-BACKEND ALTER-SYSTEM-DROP-FOLLOWER ALTER-SYSTEM-DROP-OBSERVER ALTER-SYSTEM-DROP-BACKEND ALTER-SYSTEM-DROP-BROKER CANCEL-ALTER-SYSTEM