JSP model 2 architecture

JSP 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. While the exact form of the MVC "Model" was never specified by the Model 2 design, a number of publications recommend a formalized layer to contain MVC Model code. The Java BluePrints, for example, originally recommended using EJBs to encapsulate the MVC Model.

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 1998, Sun Microsystems published a pre-release of the JavaServer Pages specification, version 0.92. In this specification, Sun laid out two methods by which JSP pages could be used. The first model (referred to as "model 1" due to its ordering in the document) was a simplistic model whereby JSP pages were standalone, disjointed entities. Logic could be contained within the page itself, and navigation between pages was typically achieved by way of hyperlinks. This fit with the then-common usage of template technology.

ColdFusion and Active Server Pages are examples of contemporary technologies that also implemented this model.

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