Some embodiments provide a non-transitory machine-readable medium that stores a program. The program observes a parameter associated with a computing system. Upon receiving a change associated with the parameter, the program further determines a routine definition from a set of routine definitions associated with the parameter. Each routine definition in the set of routine definitions specifies a set of instructions associated with a particular parameter associated with the computing system. The program also executes the set of instructions specified in the determined routine definition.