A print controller, methods, and software are disclosed. A print controller of the invention includes applications, a parameter manager, and a notification system. The applications register with parameter manager those parameters for which they want to be notified when a change occurs. As part of the registration, the applications designate a callback identifier (CID) for each of the parameters, where an individual CID may be associated with a single parameter or a plurality of related parameters. Responsive to receiving an indication of changes to one or more of the parameters, the notification system identifies the applications registered to be notified of changes to the parameters, and identifies the CIDs associated with the parameters that have changed. The notification system then transmits one or more notification messages, including the identified CIDs for the changed parameters, to each application that is registered.