CS506 Web Design and Development Assignment 5 solution fall 2012

Answer the   following questions. Each question carry equal marks:

1      Part 1

In what type of applications/scenarios   forward () and include () methods  are   used?(Marks 5)

forward() and include() methods

Include method is used when we want to include some external files in our Servlet (eg: html, javascripts). If you want to show some advertisements in your sevlet code you can include the avertisement page as an image or html file.

We use forward method to navigate the request and response object to another resouce on the same server.
suppose we want to assign a jsp to display the contents we can navigate from the servlet to jsp using forward method. here servlet is reponsible for data processing and jsp is for display (MVC pattern follows this)

 2      Part 2

Suppose you are going to develop a learning   management system in which different users access the system like student,   teachers and admin. . They have different views (interfaces) based on their privileges.   Their login request is sent to some authentication page which authenticates   the users on the basis of their provided information from database. If they   are authenticated successfully they are shown the respective view otherwise   they are sent back to the login page.

You are using templates for views (header,   footer, navigation, etc) that are already developed by some other student.   You also have to add some “news and information” portion which your   university has subscribed to RSS readers and get daily news headlines.

Identify the parts of this application where   you will use include, forward and redirect methods to implement the required features.   If you are selecting or preferring any method over the other, give its short   reason.(Marks 5)

Response.sendRedirect () This function is used, when we want to redirect the client request to some other site (i.e out of our context) or when ever we want to redirect errors. If you are using
sendRedirect (), then it will be visible to the client that means the URL which you have been redirected will be visible in the address bar. Redirect response to the client using the specified redirect location URL.
RequestDispatcher Interface:
Forward() : This can be done in two ways by Request & ServeletContext. Forwarding a request from a servlet to another resource (servlet, JSP file, or HTML file) on the server. Forward is done at server side, without the client’s knowledge. When you invoke a forward request, the request is sent to another resource on the server, without the client being informed that a different resource is going to process the request. This process occurs completely with in the web container. When a sendRedirtect method is invoked, it causes the web container to return to the browser indicating that a new URL should be requested. Because the browser issues a completely new request any object that are stored as request attributes before the redirect occurs will be lost. This extra round trip a redirect is slower than forward.

Include:Includes dynamic page information..

include: will include another file in our current file forward: will forward the current request to the forwarding page sendRediect: will call the next page but it won’t send the same request to the new page but forward will send the same request to the new page