How do you pass data (including JavaBeans) to a JSP from a servlet?-

?– (1) Request Lifetime: Using this technique to pass beans, a request dispatcher (using either “include” or forward”) can be called. This bean will disappear after processing this request has been completed. Servlet: request. setAttribute(”theBean”, myBean); RequestDispatcher rd = getServletContext(). getRequestDispatcher(”thepage. jsp”); rd. forward(request, response); JSP PAGE:<jsp: useBean id=”theBean” scope=”request” class=”. . . . . ” />(2) Session Lifetime: Using this technique to pass beans that are relevant to a particular session (such as in individual user login) over a number of requests. This bean will disappear when the session is invalidated or it times out, or when you remove it. Servlet: HttpSession session = request. getSession(true); session. putValue(”theBean”, myBean); /* You can do a request dispatcher here, or just let the bean be visible on the next request */ JSP Page:<jsp:useBean id=”theBean” scope=”session” class=”. . . ” /> 3) Application Lifetime: Using this technique to pass beans that are relevant to all servlets and JSP pages in a particular app, for all users. For example, I use this to make a JDBC connection pool object available to the various servlets and JSP pages in my apps. This bean will disappear when the servlet engine is shut down, or when you remove it. Servlet: GetServletContext(). setAttribute(”theBean”, myBean); JSP PAGE:<jsp:useBean id=”theBean” scope=”application” class=”. . . ” />

What is Servlet chaining

Servlet chaining is a technique in which two or more servlets can cooperate in servicing a single request. In servlet chaining, one servlet’s output is piped to the next servlet’s input. This process continues until the last servlet is reached. Its output is then sent back to the client.

What are cookies and how will you use them

Cookies are a mechanism that a servlet uses to have a client hold a small amount of state-information associated with the user. a) Create a cookie with the Cookie constructor: public Cookie(String name, String value) b) A servlet can send a cookie to the client by passing a Cookie object to the addCookie() method of HttpServletResponse: public void HttpServletResponse. addCookie(Cookie cookie) c) A servlet retrieves cookies by calling the getCookies() method of HttpServletRequest: public Cookie[ ] HttpServletRequest. getCookie().

What is the life cycle of a servlet?

Each Servlet has the same life cycle: a) A server loads and initializes the servlet by init () method. b) The servlet handles zero or more client’s requests through service() method. c) The server removes the servlet through destroy() method.

How to start Servlet Automatically

If present, calls the servlet’s service() method at the specified times. <run-at> lets servlet writers execute periodic tasks without worrying about creating a new Thread.

The value is a list of 24-hour times when the servlet should be automatically executed. To run the servlet every 6 hours, you could use:

<run-at>0:00, 6:00, 12:00, 18:00</run-at>

</servlet>

Explain Servlet Life Cycle

A servlet life cycle can be defined as the entire process from its creation till the destruction. The following are the paths followed by a servlet

The servlet is initialized by calling the init ()
The servlet calls service()method to process a client’s request.
The servlet is terminated by calling the destroy()
Finally, servlet is garbage collected by the garbage collector of the JVM.

Name one advantage of JSP over Servlets

Can contain HTML, JavaScript, XML and Java Code whereas Servlets can contain only Java Code, making JSPs more flexible and powerful than Servlets.

However, Servlets have their own place in a J2EE application and cannot be ignored altogether. They have their strengths too which cannot be overseen.

What do you understand by JSP translation?

JSP translation is an action that refers to the convertion of the JSP Page into a Java Servlet. This class is essentially a servlet class wrapped with features for JSP functionality.

Difference Between Servlets And JSP

Servlets and Java Server Pages are complementary APIs, both providing a means for generating dynamic Web content. A servlet is a Java class implementing the javax.servlet.Servlet interface that runs within a Web or application server’s servlet engine, servicing client requests forwarded to it through the server. A Java Server Page is a slightly more complicated beast. JSP pages contain a mixture of HTML, Java scripts (not to be confused with JavaScript), JSP elements, and JSP directives. The elements in a Java Server Page will generally be compiled by the JSP engine into a servlet, but the JSP specification only requires that the JSP page execution entity follow the Servlet Protocol.

The advantage of Java Server Pages is that they are document-centric. Servlets, on the other hand, look and act like programs. A Java Server Page can contain Java program fragments that instantiate and execute Java classes, but these occur inside an HTML template file and are primarily used to generate dynamic content. Some of the JSP functionality can be achieved on the client, using JavaScript. The power of JSP is that it is server-based and provides a framework for Web application development. Rather than choosing between servlets and Java Server Pages, you will find that most non-trivial applications will want to use a combination of JSP and servlets. In fact, the JSP 1.1 and Servlet 2.2 specifications are based around the concept of the Web application, combining the two APIs into a unified framework.

What is a JSP and what is it used for

Java Server Pages (JSP) is a platform independent presentation layer technology that comes with SUN s J2EE platform. JSPs are normal HTML pages with Java code pieces embedded in them. JSP pages are saved to *.jsp files. A JSP compiler is used in the background to generate a Servlet from the JSP page.