A device capable of flexibly changing a protocol for use for event communication in consideration of communication load applied to an event providing apparatus. The device receives an event registration request transmitted from a client apparatus, and based on the received event registration request, notifies a generated event to the client apparatus. When receiving an event registration request, the device determines whether or not communication load caused by event notification exceeds a threshold value, and based on the result of determination, decides a protocol for use for the event notification to the event registration request.