JSP and Servlets Fundamentals

A single servlet instance typically handles multiple concurrent requests using a multi-threaded model. The container creates one instance (or a pool) and dispatches multiple threads to the service() method simultaneously. Each thread handles one request, allowing efficient resource utilization. Developers must ensure thread-safety in servlet code since instance variables are shared across threads.

ServletContext provides an interface for servlets to interact with their runtime environment (the servlet container). Through ServletContext, servlets can access initialization parameters, container-wide resources, and share information with other servlets. It provides methods like getInitParameter(), getAttribute(), and log() to communicate with the container and application environment.

The HttpServletResponse interface provides the getWriter() method, which returns a PrintWriter object for sending character text data to the client. This is the standard way to write response content in servlets. HttpServletRequest (request) handles incoming data, HttpSession manages user sessions, and PrintWriter itself is the class returned, not the source of it. The leading period appears to be a typo but doesn't affect the question.

The servlet lifecycle consists of three main methods: init() (called once when servlet is initialized), service() (called for each request to handle business logic), and destroy() (called once before servlet is removed from service). All three are essential lifecycle methods, so Option D (Above All) is correct as it encompasses all of them. Option C only names destroy(), which is incomplete.

There is exactly one ServletContext object per web application. It is created by the container when the application is deployed and shared by all servlets in that application. This singleton pattern ensures all servlets access the same application-wide configuration and attributes. The context is destroyed when the application is undeployed or the container shuts down.

getAttribute() retrieves object-level attributes stored in the request scope. This is different from getParameter() which retrieves string form parameters from the query string or POST body, and getInitParameter() which retrieves servlet initialization parameters from web.xml. Attributes are typically set by the application using setAttribute() to share data between components, while parameters come from client requests.

Servlets use a multi-threaded model where a single servlet instance handles multiple requests concurrently. Each request runs in a separate thread, sharing the same servlet instance, which makes resource-efficient but requires thread-safe coding.

The getServletConfig() method returns the ServletConfig object passed to the servlet's init() method. This allows access to initialization parameters and servlet context throughout the servlet's lifecycle.

HTML and JavaScript are client-side technologies that run in the browser. JSP and Servlets are server-side Java technologies that execute on the web server to generate dynamic content.

JSP stands for Java Server Pages. It is a server-side technology that allows developers to embed Java code in HTML pages to create dynamic web content.

JSP is primarily used for creating the view/presentation layer (GUI) in web applications. It generates HTML that is sent to the browser. Controllers are better implemented as Servlets, and business logic should be in separate Java classes.

Modern servlet containers automatically map JSP files - you don't need to configure them in web.xml. The container compiles JSPs into servlets on first access. web.xml configuration is only needed for Servlets and custom URL mappings.

JSP requires a servlet container or engine with JSP support to run. Apache Tomcat and Bea WebLogic are application servers/servlet containers. JSP Engine is the generic component that processes JSP. Servlets are Java classes that run inside containers, not platforms themselves.

IBM WebSphere is a full-featured Java EE application server that supports Servlets, JSP, and EJBs. It includes enterprise features like pooled database access for major databases (DB2, Oracle) and is a comprehensive platform for enterprise Java applications.

The scriptlet element syntax in JSP is <% code %>. Scriptlets allow embedding Java code directly into JSP pages. The code inside runs during the request processing phase and can generate dynamic content.

The declaration element syntax in JSP is <%! code %>. Declaration elements are used to define methods and class-level variables that become part of the generated servlet class. Unlike scriptlets, declarations run at class initialization, not per request.

JSP comments use <%-- comment --%>. These are server-side comments that are completely removed from the generated HTML - the browser never sees them. HTML comments would be visible to users viewing page source.

JSP has four standard scopes: page (default), request, session, and application. Response is not a scope - it's an object for sending data back to the client. Scopes determine the lifespan and visibility of data.

In JSP, there are three standard JavaBean actions: useBean (to instantiate or locate a bean), setProperty (to set bean property values), and getProperty (to retrieve bean property values). Option D 'All' correctly identifies that useBean, setProperty, and getProperty are all JavaBean actions.