A data processing system is provided, which improves convenience for a user in setting an operation parameter for application software to be executed by a server apparatus connected to an image forming apparatus via a network. An extracting portion of the image forming apparatus extracts a parameter entered by the user from a parameter setting sheet bearing the parameter entered therein, and transmits the extracted parameter to the server apparatus. Application software installed in the server apparatus receiving the parameter apply various kinds of information processing to document image data transmitted from the image forming apparatus, based on the parameter extracted by the extracting portion of the image forming apparatus.