Model-View-Controller (MVC) Design Pattern

Model View Controller design pattern is used to support multiple types of users with multiple types of interfaces. The Model-View-Controller (MVC) pattern separates the modeling of the domain, the presentation, and the actions based on user input into three separate classes:

- Model: The model locates all data information for the application. It does not care about how you interpret it or how process it. It divides functionality among objects involved in maintaining and presenting data to minimize the degree of coupling between the objects.

- View: The view manages the display of information. It is responsible for maintaining the consistency in its presentation when the underlying model changes.

- Controller: The controller interprets the mouse and keyboard inputs from the user, informing the model and/or the view to change as appropriate. The actions performed on the model can be activating device, business process or changing the state of a model.

The MVC pattern allows any number of controllers to modify the same model. The strategies by which MVC can be implemented are as follows:
- For Web-based clients such as browsers, use Java Server Pages (JSP) to render the view, Servlet as the controller, and Enterprise JavaBeans (EJB) components as the model.
- For Centralized controller, a main servlet is used to make control more manageable.

Introduction to Architecture Design - WebApp Architecture

The design process for identifying the subsystems making up a system and the
framework for sub-system control and communication is architectural design. An architectural design is :
- early stage in system design process.
- conducted in parallel with other design activities.
- establishes a link among goals established for web application, content, users visiting it, and the navigation criterion.
- identifying system components and their communications.

A web application is an application that is accessed over a network such as the Internet or an intranet.Web application architecture provides an infrastructure that enables a web based system to achieve its business objectives.
The Model View Controller (MVC) architecture decouples the user interface from web application functionality and information content.

The MVC design pattern divides applications into three components:
- The Model maintains the state and data that the application represents.
- The View allows the display of information about the model to the user. It contains all interface specific functions.
- The Controller allows the user to manipulate the application. It coordinates the flow of data between model and view.

Web application architecture is defined within the context of the development environment in which the application is to be implemented.