The basic idea behind the pattern is to have 3 classes. One (the view) is a UI class which could be an winform at one time or be a asp.net webform at another time. On the other hand is the model, a class where your data lives in and returns answers to questions by exposing some functionality. In a more SOA oriented approach this model are the services.

In between there is the presenter which glues the two together. The view calls the presenter which in its turn calls the model. The model can answer directly to the method or raise callback events in case of asynchronous models. When the presenter receives the data it updates the vie