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Model View Presenter pattern

Model View Presenter (MVP) is a software design pattern that brings a lot of benefits developing web applications having GWT as frontend framework. I am going to do a brief description of this pattern. I am currently applying it on a project I am working on and I have noticed that for people coming from MVC (Model View Controller) sometimes it's hard to understand the benefits of MVP (and how to implement it): so I decided to share my experience explaining this pattern from scratch.
MVP is a derivative of the MVC pattern and it's used mainly for building user interfaces. As well as the MVC pattern, MVP decouples the model from the views and the views from the logic that controls them. This way you really have the separation of concerns for the presentation logic. The three actors of this pattern are:


  • Model: an interface defining the data to be displayed.
  • View: a passive interface that displays the data of a model and routes user commands (typically events) to the presenter to act upon the data.
  • Presenter: it retrieves data from the model and then formats it to be displayed in the views.


The MVP pattern that best fits with GWT is more similar to the Model View Presenter Controller pattern (an extension of MVP). The Presenter is split into two components, the presenter (view control logic) and the controller (abstract purpose control logic). So the View, the Presenter and the Controller are really separated and then they can vary independently. MVPC improves MVP because:


  • controllers applying different control logics can be interchanged without impacting the presenter or the view;
  • completely different views can be applied to the same controller without impacting the underlying control logic;
  • multiple related views can be coordinated by a single controller. 


The following image shows an high level architectural diagram of the MVP implementation in GWT:



In the next post we will explore more in detail this diagram and then we will see how to code everything.
 
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