"g. , "The Establishment") . Unlike the first three "filtering" mechanisms — which are derived from analysis of market mechanisms — flak is characterized by concerted and intentional efforts to manage public information. Flak from the powerful can be either direct or indirect. The direct could include the following hypothetical scenarios: Letters or phone calls from the White House to Dan Rather or William Paley Inqueries from the FCC to major television networks requesting documents used to plan and assemble a program Messages from irate executives representing advertising agencies or corporate sponsors to media officials threatening retaliation if not granted on-air reply time. The powerful can also work on the media indirectly by: Complaints delivered en masse to their own constituencies (e. g. Boat Lighting Model Ship, stockholders, employees) about media bias, Generation of mass advertising that does the same, By funding watchdog groups or think tanks engineered to expose and attack deviations in media coverage that endanger vital elite interests. By funding political campaigns that elect politicians who will be more willing to curb any such media deviations. "

" 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. A view object can register itself with the model and listen for changes but the model itself remains view-agnostic. The controller does not pass domain objects (the model) to the view although it might issue a command telling the view to update itself. The user interface waits for further user interactions, which begins the cycle anew. Benefits and liabilities Although widely used, MVC has both advantages and disadvantages compared to other design options, and individual circumstances should be used to choose the most appropriate design. We discuss some of those here. Model Wooden Sailing Ship View instability vs. model stability If constructed correctly, models can enjoy a fair degree of stability (owing to the stability of the domain model), whereas user interface code usually undergoes frequent and sometimes dramatic change (typically because of usability problems, the need to support growing classes of users, or simply the need to keep the application looking "fresh"). "