MVC

Basic MVC Architecture

Model View Controller or MVC as it is popularly called, is a software design pattern for developing web applications. A Model View Controller pattern is made up of the following three parts:

• Model - The lowest level of the pattern which is responsible for maintaining data.
• View - This is responsible for displaying all or a portion of the data to the user.
• Controller - Software Code that controls the interactions between the Model and View.

MVC is popular as it isolates the application logic from the user interface layer and supports separation of concerns. Here the Controller receives all requests for the application and then works with the Model to prepare any data needed by the View. The View then uses the data prepared by the Controller to generate a final presentable response. The MVC abstraction can be graphically represented as follows.

The model

The model is responsible for managing the data of the application. It responds to the request from the view and it also responds to instructions from the controller to update itself.

The view

A presentation of data in a particular format, triggered by a controller's decision to present the data. They are script based templating systems like JSP, ASP, PHP and very easy to integrate with AJAX technology.

The controller

The controller is responsible for responding to user input and perform interactions on the data model objects. The controller receives the input, it validates the input and then performs the business operation that modifies the state of the data model.

Struts2 is a MVC based framework. In the coming chapters, let us see how we can use the MVC methodology within Struts2.

Struts2 is popular and mature web application framework based on the MVC design pattern. Struts2 is not just the next version of Struts 1, but it is a complete rewrite of the Struts architecture.

The WebWork framework started off with Struts framework as the basis and its goal was to offer an enhanced and improved framework built on Struts to make web development easier for the developers.

After some time, the Webwork framework and the Struts community joined hands to create the famous Struts2 framework.

Struts 2 framework features:

Here are some of the great features that may force you to consider Struts2:

• POJO forms and POJO actions - Struts2 has done away with the Action Forms that were an integral part of the Struts framework. With Struts2, you can use any POJO to receive the form input. Similarly, you can now see any POJO as an Action class.
• Tag support - Struts2 has improved the form tags and the new tags allow the developers to write less code.
• AJAX support - Struts2 has recognised the take over by Web2.0 technologies, and has integrated AJAX support into the product by creating AJAX tags, that function very similar to the standard Struts2 tags.
• Easy Integration - Integration with other frameworks like Spring, Tiles and SiteMesh is now easier with a variety of integration available with Struts2.
• Template Support - Support for generating views using templates.
• Plugin Support - The core Struts2 behaviour can be enhanced and augmented by the use of plugins. A number of plugins are available for Struts2.
• Profiling - Struts2 offers integrated profiling to debug and profile the application. In addition to this, Struts also offers integrated debugging with the help of built in debugging tools.
• Easy to modify tags - Tag markups in Struts2 can be tweaked using Freemarker templates. This does not require JSP or java knowledge. Basic HTML, XML and CSS knowledge is enough to modify the tags.
• Promote less configuration - Struts2 promotes less configuration with the help of using default values for various settings. You don't have to configure something unless it deviates from the default settings set by Struts2.
• View Technologies: - Struts2 has a great support for multiple view options (JSP, Freemarker, Velocity and XSLT)

The above are just the top ten features of Struts 2 that makes it an entreprise ready framework.

Struts 2 disadvantages:

Though Struts 2 comes with a list of great features but I would not forget to mention few negative points about Struts 2 and would need lots of improvments:

• Bigger learning curve - To use MVC with Struts, you have to be comfortable with the standard JSP, Servlet APIs and a large & elaborate framework.
• Poor documentation - Compared to the standard servlet and JSP APIs, Struts has fewer online resources, and many first-time users find the online Apache documentation confusing and poorly organized.
• Less transparent - With Struts applications, there is a lot more going on behind the scenes than with normal Java-based Web applications which makes it difficult to understand the framework.

Final note, A good framework should provide generic behavior that many different types of applications can make use of it. Struts 2 is one of the best web framework and being highly used for the development of Rich Internet Applications (RIA).