If your online store has failed, how could (your store) give a notice? A general failure can also compromise (affect) your store's ability to ask for help ... The mechanism is this: A watchdog timer (or just a watchdog) is an electronic or software timer that is used to detect and recover from malfunctions.
During normal operation, your store can regularly reset (kick) the watchdog timer to prevent timeout. If, due to hardware failure or serious software error, the store is unable to signal the watchdog to life, time will pass and a timeout signal will automatically be generated. This "timeout" signal is used to alert of the need and initiate corrective actions. Corrective actions generally include placing the computer system in a safe state and restoring normal system operation.