the solid arrows indicates a physical data path and notification direction and the dotted arrows indicate a logical data path and notification direction notification recovery is initiated in notification manager 256 upon the occurrence of any one of the following system operations server startup server failover controller startup controller failover control network communication failure and recovery and addition via configuration of a new process controller in the exemplary embodiment supervisory controller 120 is the server with respect to pcm 201 and the two are coupled by a local area network architecture notification recovery is needed in those situations in which notification clients and notification producers become unsynchronized usually due to some system or equipment fault e g controller network workstation etc and the repair thereof in on advantageous embodiment of the present invention notification recovery is carried out entirely by the communication application layer that serves the client application s using the notifications it is the application layer in the notification client node the 34 notification subscriber 34 that commands a notification recovery the application layer does notification recovery on behalf of a notification client when the notification client needs it so that neither the notification client application nor the function layer of the notification producer are burdened by this function notification generators exist in pcm 201 as user configured functional blocks that are managed by a control execution environment cee 202 the cee 202 may receive when needed a notification recovery command from the notification manager 256 in supervisory controller 120 and in turn commands each functional block to generate.