10- What are the differences between forward() and sendRedirect() methods?
Some key differences between the two methods are:

a. A Forward is performed internally by the servlet whereas a redirect is a two-step process where the web application instructs the web browser to fetch a second/different URL
b. The browser and the user is completely unaware that a forward has taken place (The URL Remains intact) whereas in case of redirect, both the browser and the user will be made aware of the action including a change to the URL
c. The resource to which control is being forwarded has to be part of the same context as the one that is actually calling it whereas in case of redirect this is not a restriction.
d. Forwards are faster than redirects. Redirects are slower because it is actually handling two browser requests in place of forward’s one.

11- What are the difference between the include() and forward() methods? 
The key differences between the two methods are:

a. The include() method inserts the contents of the specified resource directly into the flow of the servlet response, as if it were part of the calling servlet, whereas the forward() is used to show a different resource in place of the servlet that was originally called
b. The include() is often used to include common text or template markup that may be included in many servlets whereas forward() is often used where a servlet plays the role of a controller, processes some input and decides the outcome by returning a particular page response where control is transferred to a different resource

12- What is the use of the servlet wrapper classes?
The HttpServletRequestWrapper and HttpServletResponseWrapper classes are designed to make it easy for developers to create custom implementations of the servlet request and response types. The classes are constructed with the standard HttpServletRequest and HttpServletResponse instances respectively and their default behavior is to pass all method calls directly to the underlying objects.

13- What is a deployment descriptor? 
A deployment descriptor is an XML document. It defines a component’s deployment settings. It declares transaction attributes and security authorization for an enterprise bean. The information provided by a deployment descriptor is declarative and therefore it can be modified without changing the source code of a bean.
The Java EE server reads the deployment descriptor at run time and acts upon the components accordingly.

14- What is the difference between the getRequestDispatcher(String path) method of javax.servlet.ServletRequest interface and javax.servlet.ServletContext interface?
The getRequestDispatcher(String path) method of javax.servlet.ServletRequest interface accepts parameter the path to the resource to be included or forwarded to, which can be relative to the request of the calling servlet. If the path begins with a “/” it is interpreted as relative to the current context root, whereas, the getRequestDispatcher(String path) method of javax.servlet.ServletContext interface cannot accept relative paths. All path must start with a “/” and are interpreted as relative to current context root.

15- What is the < load-on-startup > element of the deployment descriptor?
The element of a deployment descriptor is used to load a servlet file when the server starts instead of waiting for the first request. This setting by which a servlet is loaded even before it gets its first request is called pre-initialization of a servlet. It is also used to specify the order in which the files are to be loaded. The container will load the servlets in the order specified in this element.

16- What is servlet lazy loading? 
Lazy servlet loading means – the container does not initialize the servlets as soon as it starts up. Instead it initializes servlets when they receive their first ever request. This is the standard or default behavior. If you want the container to load your servlet at start-up then use pre-initialization using the load-on-startup element in the deployment descriptor.

17- What is Servlet Chaining?
Servlet Chaining is a method where the output of one servlet is piped or passed onto a second servlet. The output of the second servlet could be passed on to a third servlet, and so on. The last servlet in the chain returns the output to the Web browser.

18- What are filters?
Filters are Java components that are used to intercept an incoming request to a Web resource or the response that is sent back from the resource. It is used to abstract any useful information contained in the request or response. Some of the important functions performed by filters are:
Security checks
Modifying the request or response
Data compression
Logging and auditing
Response compression
Filters are configured in the deployment descriptor of a Web application. Hence, a user is not required to recompile anything to change the input or output of the Web application.

19- What are the functions of the Servlet container?
The functions of the Servlet container are as follows:

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