An object is to provide an application platform in which, before a screen of an application is displayed, another application can display any screen by an optional determination standard. When the screen of a first application is to be displayed, if a second application exists monitoring a function of an image forming apparatus included in the first application, the second application is notified of the function information before the screen of the first application is displayed. Then, for realizing the above, the use function of the image forming apparatus is registered for each of the first applications, and the monitor function is registered for each of the second applications.