A scanner that provides WSD standard scan service does not allow the notification and identification by a client PC of scan parameters, such as a resolution and a reading range, that are selected by a user in push scan on a panel, for example, attached to the scanner body. This prevents the push scan with the user-specified scan parameters. Accordingly, an event that temporarily limits the scanning functions is issued to inhibit the specification of parameters excluding user-specified scan parameters from a client PC. Thus, the client PC can instruct the scanning with the user-specified parameters, and the push scan requested by the user can be implemented. The limitation is valid only to the destination client of the push scan.