" 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. For example, an operating system command to display the current time. It displays the time and is done; it does not wait for events. Kit Model Museum Quality Ship Wooden For more information, see: Event-driven_programming Implementations The pattern was first described in 1979 by Trygve Reenskaug, then working on Smalltalk at Xerox research labs. This original implementation inspired many other GUI frameworks such as: The NeXTSTEP and OPENSTEP development environments encourage the use of MVC. "

", user presses a button) A controller contains the input part of the user interface. The controller accesses the model, possibly updating it in a way appropriate to the user's action (e. g. , controller updates user's shopping cart) A view uses the model to generate an appropriate user interface (e. g. , view produces a screen listing the shopping cart contents). The view gets its own data from the model (or direct from the data access layer - sometimes there is no domain logic to do). Kit Model Sailing Ship The model should have no direct knowledge of the view. However, the observer pattern can be used to provide some indirection between model and view, allowing the model to notify interested parties of a change. "