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Model View Controller�MVC Architechture

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�Need for MVC

Servlets are great when your application requires a lot of real programming to accomplish its task. As we know, servlets can manipulate HTTP status codes and headers, use cookies, track sessions, save information between requests, compress pages, access databases, perform many other tasks flexibly and efficiently. But, generating HTML with servlets can be tedious and can yield a result that is hard to modify.

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Need Of MVC contd..

That’s where JSP comes in: JSP lets you separate

much of the presentation from the dynamic content. That way, you can write the HTML in the normal manner, even using HTML-specific tools and putting your Web content developers to work on your JSP documents. JSP expressions, scriptlets, and declarations let you insert simple Java code into the servlet that results from the JSP page, and directives let you control the overall layout of the page.

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Need Of MVC contd…

The assumption behind a JSP document is that it provides a single overall presentation.

Servlet is good in writing business logics .

JSP is good in data presentation.

The solution is to use both servlets and JSP. This approach, known as the Model View Controller (MVC) or Model 2 architecture. The original request is handled by a servlet.

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Need Of MVC contd…

The servlet invokes the business-logic and data-access code and creates beans to represent the results (that’s the model). Then, the servlet decides which JSP page is appropriate to present those particular results and forwards the request there (the JSP page is the view).

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MVC Architecture :

The most important point about MVC is the idea of separating the business logic and data access layers from the presentation layer.

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Implementing MVC

Steps required for implementing MVC:

  • Define beans to represent the data.
  • Use a servlet to handle requests.
  • Populate the beans.
  • Store the bean in the request, session, or servlet context.
  • Forward the request to a JSP page.
  • Extract the data from the beans.

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THE END

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