JSP :part 18; Model View Controller Architecture

Model View Controller Architecture

In Model 1, a request is made to a JSP and then that JSP handles all responsibilities for the request, including processing the request, validating data, handling the business logic, and generating a response. The Model 1 architecture is commonly used in smaller, simple task applications due to its ease of development. Although conceptually simple, this architecture is not conducive to large-scale application development because, inevitably, a great deal of functionality is duplicated in each JSP. Also, the Model 1 architecture unnecessarily ties together the business logic and presentation logic of the application.

JSP Model 2 Architecture

Model 2 is a complex design pattern used in the design of Java Web applications which separates the display of content from the logic used to obtain and manipulate the content. Since Model 2 drives a separation between logic and display, it is usually associated with the model–view– controller (MVC) paradigm

In a Model 2 application, requests from the client browser are passed to the controller. The controller performs any logic necessary to obtain the correct content for display. It then places the content in the request (commonly in the form of a JavaBean or POJO) and decides which view it will pass the request to. The view then renders the content passed by the controller. Model 2 is recommended for medium- and large-sized applications.

In JSP Model 2 architecture, JSP is used for creating the view for the application. A centralized S ervlet is used to handle all the request for the application. The Servlet works as the controller for the application. It then uses the Java beans for processing the business logic and getting the data (Model) from the database. Finally it uses the JSP to render the view which is displayed to the user. The MVC architecture is very popular architecture and there are many frameworks available for developing Java based web applications. MVC based frameworks are: Struts 2 , JSF , Spring MVC etc.

Scripting elements calling servlet code directly

 • Scripting elements calling servlet code indirectly (by means of utility classes)

 • Beans

 • Servlet/JSP combo (MVC 2)

• MVC 2 with JSP expression language (JSP 2.1)

 • Custom tags

 • MVC with beans, JSTL tags, and a framework like Struts or JSF.

MVC2 Architecture is needed when: – A single request will result in multiple substantially different-looking results. – You have a large development team with different team members doing the Web development and the business logic. – You perform complicated data processing, but have a relatively fixed layout.