" The 'model-view-controller' paradigm introduces the controller object in between the view (the GUI class) and the model (the object) to communicate between the other two objects. The actual implementation of the controller object can vary quite a bit, but the idea of an object to 'transform' events to changes in data and execution of methods is the essence of this pattern . What does "event driven" mean? Was there ever an application which did not respond to user events. . ? Just because an application responds to events does not mean it is "event driven". Event driven means it spends much of its time waiting for an event and then takes action if and when an event occurs. Contrast this with some programs that do not respond to events at all, but simply do their job and terminate. Francis Model Portfolio For example, an operating system command to display the current time. It displays the time and is done; it does not wait for events. "

" Analysis models are in a descriptive reference mode to their originals. (2) prescriptive, i. e. , the model prescribes the original. If the deviation from model to original cannot be tolerated then the original has to be changed. Design models are in a prescriptive reference mode to their originals, i. e. Boy Gallery Girl Model, the implementation. (3) idealizing, i. "