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Ans. Session tracking is a mechanism that servlets use to maintain state about a series requests from the same user across some period of time. The methods used for session tracking are:
User Authentication - occurs when a web server restricts access to some of its resources to only those clients that log in using a recognized username and password
Hidden form fields - fields are added to an HTML form that are not displayed in the client's browser. When the form containing the fields is submitted, the fields are sent back to the server
URL rewriting - every URL that the user clicks on is dynamically modified or rewritten to include extra information. The extra information can be in the form of extra path information, added parameters or some custom, server-specific URL change.
Cookies - a bit of information that is sent by a web server to a browser and which can later be read back from that browser.
HttpSession- places a limit on the number of sessions that can exist in memory.
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Very frequently asked.Usually among first few questions.
Ans. MVC is a Design Pattern that facilititates loose coupling by segregating responsibilities in a Web application
1. Controller receives the requests and handles overall control of the request
2. Model holds majority of the Business logic, and
3. View comprise of the view objects and GUI component
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Ans. Cookie and Session are used to store the user information. Cookie stores user information on client side and Session does it on server side. Primarily, Cookies and Session are used for authentication, user preferences, and carrying information across multiple requests. Session is meant for the same purpose as the cookie does. Session does it on server side and Cookie does it on client side. One more thing that quite differentiates between Cookie and Session. Cookie is used only for storing the textual information. Session can be used to store both textual information and objects.
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Ans. The jsp scriptlet tag can only declare variables not methods whereas jsp declaration tag can declare variables as well as methods.
The declaration of scriptlet tag is placed inside the _jspService() method whereas The declaration of jsp declaration tag is placed outside the _jspService() method.
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LikeDiscussCorrect / Improve  j2ee   jsp   scriptlet tag   declaraation tag   web application
Q6. What is meant by an "asynchronous event." Give some examples ?
Ans. An asynchronous event is one that occurs at an unpredictable time outside the control of the program that the CPU is running. It is not "synchronized" with the program.
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Ans. A cookie is a small piece of text stored on a user's computer by the browser for a specific domain. Commonly used for authentication, storing site preferences, and server session identification.
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Ans. Spring configuration file is an XML file. This file contains the classes information and describes how these classes are configured and introduced to each other.
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Ans. The Spring container is able to autowire relationships between collaborating beans. This means that it is possible to automatically let Spring resolve collaborators (other beans) for your bean by inspecting the contents of the BeanFactory without using and elements.
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Ans. Translation of JSP PageCompilation of JSP PageClassloading (class file is loaded by the classloader)Instantiation (Object of the Generated Servlet is created).Initialization ( jspInit() method is invoked by the container).Reqeust processing ( _jspService() method is invoked by the container).Destroy ( jspDestroy() method is invoked by the container).
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Ans. http protocol on its own is stateless. So it helps in identifying the relationship between multiple stateless request as they come from a single source.
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Ans. Session info in the request can be intercepted and hence a vulnerability. Cookie can be read and write by respective domain only and make sure that right session information is being passed by the client.
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Q23. Have you ever faced any problem due to caching?
Ans. Yes , sometime we receive issues related to outdated pages being rendered to the user. In those cases we clear the cache and then try to investigate the reason for that. Sometime the issue is due to comparatively high refresh interval. In those cases we reduce the cache refresh interval.
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Ans. The load-on-startup element of web-app loads the servlet at the time of deployment or server start if value is positive. It is also known as pre initialization of servlet.You can pass positive and negative value for the servlet.
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