Why do you use superclass init method inside your init method in a servlet?

What is servlet filtering?

The Essentials of Filters The Java Servlet specification version 2.3 introduces a new component type, called a filter. A filter dynamically intercepts requests and responses to transform or use the information contained in the requests or responses. Filters typically do not themselves create responses, but instead provide universal functions that can be "attached" to any type of servlet or JSP page. Filters are important for a number of reasons. First, they provide the ability to encapsulate recurring tasks in reusable units. Organized developers are constantly on the lookout for ways to modularize their code. Modular code is more manageable and documentable, is easier to debug, and if done well, can be reused in another setting. Second, filters can be used to transform the response from a servlet or a JSP page. A common task for the web application is to format data sent back to the client. Increasingly the clients require formats (for example, WML) other than just HTML. To accommodate these clients, there is usually a strong component of transformation or filtering in a fully featured web application. Many servlet and JSP containers have introduced proprietary filter mechanisms, resulting in a gain for the developer that deploys on that container, but reducing the reusability of such code. With the introduction of filters as part of the Java Servlet specification, developers now have the opportunity to write reusable transformation components that are portable across containers. Filters can perform many different types of functions. Authentication-Blocking requests based on user identity. Logging and auditing-Tracking users of a web application. Image conversion-Scaling maps, and so on. Data compression-Making downloads smaller. Localization-Targeting the request and response to a particular locale. XSL/T transformations of XML content-Targeting web application responses to more that one type of client. These are just a few of the applications of filters. There are many more, such as encryption, tokenizing, triggering resource access events, mime-type chaining, and caching. tasks: Querying the request and acting accordingly Blocking the request and response pair from passing any further. Modifying the request headers and data. You do this by providing a customized version of the request. Modifying the response headers and data. You do this by providing a customized version of the response. We'll outline the filter API, and describe how to develop customized requests and responses. Programming the filter is only half the job of using filters-you also need to configure how they are mapped to servlets when the application is deployed in a web container. This decoupling of programming and configuration is a prime benefit of the filter mechanism: You don't have to recompile anything to change the input or output of your web application. You just edit a text file or use a tool to change the configuration. For example, adding compression to a PDF download is just a matter of mapping a compression filter to the download servlet. You can experiment with filters easily because they are so easy to configure. The last section of this paper shows how to use the very flexible filter configuration mechanism. Once you have read this paper, you will be armed with the knowledge to implement your own filters and have a handy bag of tricks based on some common filter types. Programming Filters The filter API is defined by the Filter, FilterChain, and FilterConfig interfaces in the javax.servlet package. You define a filter by implementing the Filter interface. A filter chain, passed to a filter by the container, provides a mechanism for invoking a series of filters. A filter config contains initialization data. The most important method in the Filter interface is the doFilter method, which is the heart of the filter. This method usually performs some of the following actions: Examines the request headers Customizes the request object if it wishes to modify request headers or data or block the request entirely Customizes the response object if it wishes to modify response headers or data Invokes the next entity in the filter chain. If the current filter is the last filter in the chain that ends with the target servlet, the next entity is the resource at the end of the chain; otherwise, it is the next filter that was configured in the WAR. It invokes the next entity by calling the doFilter method on the chain object (passing in the request and response it was called with, or the wrapped versions it may have created). Alternatively, it can choose to block the request by not making the call to invoke the next entity. In the latter case, the filter is responsible for filling out the response. Examines response headers after it has invoked the next filter in the chain Throws an exception to indicate an error in processing In addition to doFilter, you must implement the init and destroy methods. The init method is called by the container when the filter is instantiated. If you wish to pass initialization parameters to the filter you retrieve them from the FilterConfig object passed to init. Example: Logging Servlet Access Now that you know what the main elements of the filter API are, let's take a look at a very simple filter that does not block requests, transform responses, or anything fancy-a good place to start learning the basic concepts of the API. Consider web sites that track the number of users. To add this capability to an existing web application without changing any servlets you could use a logging filter. HitCounterFilter increments and logs the value of a counter when a servlet is accessed. In the doFilter method, HitCounterFilter first retrieves the servlet context from the filter configuration object so that it can access the counter, which is stored as a context attribute. After the filter retrieves, increments, and writes the counter to a log, it invokes doFilter on the filter chain object passed into the original doFilter method. The elided code is discussed in Programming Customized Requests and Responses. public final class HitCounterFilter implements Filter { private FilterConfig filterConfig = null; public void init(FilterConfig filterConfig) throws ServletException { this.filterConfig = filterConfig; } public void destroy() { this.filterConfig = null; } public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { if (filterConfig == null) return; StringWriter sw = new StringWriter(); PrintWriter writer = new PrintWriter(sw); Counter counter = (Counter)filterConfig. getServletContext(). getAttribute("hitCounter"); writer.println(); writer.println("==============="); writer.println("The number of hits is: " + counter.incCounter()); writer.println("==============="); // Log the resulting string writer.flush(); filterConfig.getServletContext(). log(sw.getBuffer().toString()); ... chain.doFilter(request, wrapper); ... Example: Modifying the Request Character Encoding Currently, many browsers do not send character encoding information in the Content-Type header of an HTTP request. If an encoding has not been specified by the client request, the container uses a default encoding to parse request parameters. If the client hasn't set character encoding and the request parameters are encoded with a different encoding than the default, the parameters will be parsed incorrectly. You can use the method setCharacterEncoding in the ServletRequest interface to set the encoding. Since this method must be called prior to parsing any post data or reading any input from the request, this function is a prime application for filters. Such a filter is contained in the examples distributed with the Tomcat 4.0 web container. The filter sets the character encoding from a filter initialization parameter. This filter could easily be extended to set the encoding based on characteristics of the incoming request, such as the values of the Accept-Language and User-Agent headers, or a value saved in the current user's session. public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { String encoding = selectEncoding(request); if (encoding != null) request.setCharacterEncoding(encoding); chain.doFilter(request, response); } public void init(FilterConfig filterConfig) throws ServletException { this.filterConfig = filterConfig; this.encoding = filterConfig.getInitParameter("encoding"); } protected String selectEncoding(ServletRequest request) { return (this.encoding); } Programming Customized Requests and Responses Look at a filter that modifies the request from or response back to the client. There are many ways for a filter to modify a request or response. For example, a filter could add an attribute to the request or it could insert data in or otherwise transform the response. A filter that modifies a response must usually capture the response before it is returned to the client. The way to do this is to pass the servlet that generates the response a stand-in stream. The stand-in stream prevents the servlet from closing the original response stream when it completes and allows the filter to modify the servlet's response. In order to pass this stand-in stream to the servlet, the filter creates a response "wrapper" that overrides the getWriter or getOutputStream method to return this stand-in stream. The wrapper is passed to the doFilter method of the filter chain. Wrapper methods default to calling through to the wrapped request or response object. This approach follows the well-known Wrapper or Decorator pattern described in Design Patterns, Elements of Reusable Object-Oriented Software. The following sections describe how the hit counter filter described earlier and other types of filters use wrappers. To override request methods, you wrap the request in an object that extends ServletRequestWrapper or HttpServletRequestWrapper. To override response methods, you wrap the response in an object that extends ServletResponseWrapper or HttpServletResponseWrapper. The hit counter filter described in Programming Filters inserts the value of the counter into the response. The elided code from HitCounterFilter is: PrintWriter out = response.getWriter(); CharResponseWrapper wrapper = new CharResponseWrapper( (HttpServletResponse)response); chain.doFilter(request, wrapper); if(wrapper.getContentType().equals("text/html")) { CharArrayWriter caw = new CharArrayWriter(); caw.write(wrapper.toString().substring(0, wrapper.toString().indexOf("")-1)); caw.write(" \nYou are visitor number " + counter.getCounter() + ""); caw.write("\n"); response.setContentLength(caw.toString().length()); out.write(caw.toString()); } else out.write(wrapper.toString()); out.close(); HitCounterFilter wraps the response in a CharResponseWrapper. CharResponseWrapper overrides the getWriter method to return a stand-in stream into which the servlet at the end of the filter chain writes its response. When chain.doFilter returns, HitCounterFilter retrieves the servlet's response from PrintWriter and writes it to a buffer if it is an HTML response. The filter inserts the value of the counter into the buffer, resets the content length header of the response, and finally writes the contents of the buffer to the response stream. public class CharResponseWrapper extends HttpServletResponseWrapper { private CharArrayWriter output; public String toString() { return output.toString(); } public CharResponseWrapper(HttpServletResponse response){ super(response); output = new CharArrayWriter(); } public PrintWriter getWriter(){ return new PrintWriter(output); } } Example: Compressing the Response Another example of a filter that modifies the response is the compression filter contained in the examples distributed with the Tomcat servlet engine. Although high-speed Internet connections are becoming more commonplace, there is still a need to use bandwidth effectively. A compression filter is handy because you can attach it to any servlet to reduce the size of a response. Like the hit counter filter, the compression filter creates a stand-in stream, in this case CompressionResponseStream, for the servlet to write to and wraps the response passed to the servlet. The filter creates the wrapper and stand-in stream only if the client can accept a compressed response. The servlet writes its response to the compression stream it retrieves from the wrapper. CompressionResponseStream overrides the write method to write response data to a GZIPOutputStream once the data is larger than a threshold passed as an initialization parameter to the filter: public void write(int b) throws IOException { ... if ((bufferCount >= buffer.length) (count>=compressionThreshold)) { compressionThresholdReached = true; } if (compressionThresholdReached) { writeToGZip(b); } else { buffer[bufferCount++] = (byte) b; count++; } } Example: Transforming the Response The last filter we'll discuss is an XSLT filter. XSLT is a language for transforming XML data. You can use XSLT to transform an XML document to end user-oriented formats such as HTML or PDF, or to another XML format. Some example applications include: Converting an XML document in a format required by one company to the format required by another company. Customizing the look and feel of a web page based on user preferences. Enabling the same web application to respond to different types of clients, for example, WML phones and cHTML phones, by looking at the User-Agent header and choosing a stylesheet. Consider a web service that responds to requests for product inventory. The following XML document is an example of such a response: 123 Web Servers for Fun and Profit 10 $17.95 The following XSL stylesheets render this XML document as a user-oriented description of the inventory in HTML format and as a machine-oriented version in XML format. There are copies of available. The following XSLT filter uses the stylesheets to transform the response depending on the value of a request parameter. The filter sets content type of the response according to the request parameter. The response is then wrapped in a CharResponseWrapper and passed to the doFilter method of the filter chain. The last element in the filter chain is a servlet that returns the inventory response described earlier. When doFilter returns, the filter retrieves the response data from the wrapper and transforms it using the stylesheet. public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { String contentType; String styleSheet; String type = request.getParameter("type"); if (type == null type.equals("")) { contentType = "text/html"; styleSheet = "/xml/html.xsl"; } else { if (type.equals("xml")) { contentType = "text/plain"; styleSheet = "/xml/xml.xsl"; } else { contentType = "text/html"; styleSheet = "/xml/html.xsl"; } } response.setContentType(contentType); String stylepath=filterConfig.getServletContext(). getRealPath(styleSheet); Source styleSource = new StreamSource(stylePath); PrintWriter out = response.getWriter(); CharResponseWrapper responseWrapper = new CharResponseWrapper( (HttpServletResponse)response); chain.doFilter(request, wrapper); // Get response from servlet StringReader sr = new StringReader( new String(wrapper.getData())); Source xmlSource = new StreamSource((Reader)sr); try { TransformerFactory transformerFactory = TransformerFactory.newInstance(); Transformer transformer = transformerFactory. newTransformer(styleSource); CharArrayWriter caw = new CharArrayWriter(); StreamResult result = new StreamResult(caw); transformer.transform(xmlSource, result); response.setContentLength(caw.toString().length()); out.write(caw.toString()); } catch(Exception ex) { out.println(ex.toString()); out.write(wrapper.toString()); } ) Specifying Filter Configuration Now that we have seen how to program a filter, the last step is to specify how to apply it to a web component or a set of web components. To map a filter to a servlet you: Declare the filter using the element in the web application deployment descriptor. This element creates a name for the filter and declares the filter's implementation class and initialization parameters. Map the filter to a servlet by defining a element in the deployment descriptor. This element maps a filter name to a servlet by name or by URL pattern. The following elements show how to specify the elements needed for the compression filter. To define the compression filter you provide a name for the filter, the class that implements the filter, and name and value of the threshold initialization parameter. Compression Filter CompressionFilter compressionThreshold 10 The filter-mapping element maps the compression filter to the servlet CompressionTest. The mapping could also have specified the URL pattern /CompressionTest. Note that the filter, filter-mapping, servlet, and servlet-mapping elements must appear in the web application deployment descriptor in that order. Compression Filter CompressionTest CompressionTest CompressionTest CompressionTest /CompressionTest Note that this mapping causes the filter to be called for all requests to the CompressionTest servlet and to any servlet JSP or static content mapped to the URL pattern /CompressionTest. If you want to log every request to a web application, you would map the hit counter filter to the URL pattern /*. Here's the deployment descriptor distributed with the examples: ?xml version="1.0" encoding="ISO-8859-1"?> XSLTFilter XSLTFilter HitCounterFilter HitCounterFilter HitCounterFilter /* XSLTFilter FilteredFileServlet FilteredFileServlet FileServlet FilteredFileServlet /ffs As you can see, you can map a filter to one or more servlets and you can map more than one filter to a servlet. This is illustrated in Figure 1, where filter F1is mapped to servlets S1, S2, and S3, filter F2 is mapped to servlet S2, and filter F3 is mapped to servlets S1 and S2. Figure 1 Filter to Servlet Mapping Recall that a filter chain is one of the objects passed to the doFilter method of a filter. This chain is formed indirectly via filter mappings. The order of the filters in the chain is the same as the order that filter mappings appear in the web application deployment descriptor. When a URL is mapped to servlet S1, the web container invokes the doFilter method of F1. The doFilter method of each filter in S1's filter chain is invoked by the preceding filter in the chain via the chain.doFilter method. Since servlet S1's filter chain contains filters F1 and F3, F1's call to chain.doFilter invokes the doFilter method of filter F3. When F3's doFilter method completes, control returns to F1's doFilter method. The deployment descriptor just discussed puts the hit counter and XSLT filter in the filter chain of FilteredFileServlet. The hit counter filter logs access whenever FilteredFileServlet is invoked, but inserts the value of the counter into the response after the XSLT transformation only if the response type is HTML: Conclusion The filter mechanism provides a way to encapsulate common functionality in a component that can reused in many different contexts. Filters are easy to write and configure as well as being portable and reusable. In summary, filters are an essential element in a web developer's toolkit. Acknowledgments The character encoding filter was developed by Craig McClanahan of Sun Microsystems, the compression filter was developed by Amy Roh of Sun Microsystems, and the XSLT filter was provided by Alan Canon of National Processing Company. Resources You can get the character encoding and compression filters by downloading Tomcat 4.0. The character encoding filter is located in the TOMCAT_HOME/webapps/examples/WEB-INF/classes/filters directory. The compression filter is located in the TOMCAT_HOME/webapps/examples/WEB-INF/classes/compressionFilters directory. You can download a zip file containing the other filters described in this paper from here. To compile and run the XSLT filter, you'll need to obtain an XML parser and transformation engine from http://java.sun.com/xml/download.html For further information about the technologies described in this paper, see the following resources: http://java.sun.com/products/servlet http://www.w3.org/XML http://www.w3.org/Style/XSL http://java.sun.com/xml

How do you get servlet context instance to servlet?

You can get the ServletContext instance in a servlet by using the getServletContext() method provided by the HttpServlet class, which is the base class for servlets. This method returns the ServletContext object associated with the servlet. For example: ServletContext context = getServletContext();

Describe the life cycle of servelet?

Each servlet has the same life cycle: * A server loads and initializes the servlet * The servlet handles zero or more client requests * The server removes the servlet (some servers do this step only when they shut down) == When a server loads a servlet, the server runs the servlet's init method. Initialization completes before client requests are handled and before the servlet is destroyed. Even though most servlets are run in multi-threaded servers, servlets have no concurrency issues during servlet initialization. The server calls the init method once, when the server loads the servlet, and will not call the init method again unless the server is reloading the servlet. The server can not reload a servlet until after the server has destroyed the servlet by calling the destroy method. == After initialization, the servlet is able to handle client requests. This part of the servlet life cycle was handled in the previous lesson. == Servlets run until the server are destroys them, for example, at the request of a system administrator. When a server destroys a servlet, the server runs the servlet's destroy method. The method is run once; the server will not run that servlet again until after the server reloads and reinitializes the servlet. When the destroy method runs, another thread might be running a service request. The Handling Service Threads at Servlet Termination lesson shows you how to provide a clean shutdown when there could be long-running threads still running service requests.

How does Apache httpd work?

Tomcat is a servlet container, and the following is how a servlet container works The init, service, and destroy methods are the servlet's lifecycle methods. The init method is called once by the servlet container after the servlet class has been instantiated to indicate to the servlet that it being placed into service. The init method must complete successfully before the servlet can receive any requests. A servlet programmer can override this method to write initialization code that needs to run only once, such as loading a database driver, initializing values, and so on. In other cases, this method is normally left blank. The service method is then called by the servlet container to allow the servlet to respond to a request. The servlet container passes a javax.servlet.ServletRequest object and a javax.servlet.ServletResponse object. The ServletRequest object contains the client's HTTP request information and the ServletResponse encapsulates the servlet's response. These two objects enable you to write custom code that determines how the servlet services the client request. The servlet container calls the destroy method before removing a servlet instance from service. This normally happens when the servlet container is shut down or when the servlet container needs some free memory. This method is called only after all threads within the servlet's service method have exited or after a timeout period has passed. After the servlet container calls destroy, it will not call the service method again on this servlet. The destroy method gives the servlet an opportunity to clean up any resources that are being held (for example, memory, file handles, and threads) and make sure that any persistent state is synchronized with the servlet's current state in memory. For Better Picture, Visit below article full of images to clear the concept : http://shivasoft.in/blog/java/servlet/how-container-handles-the-servlet-request/

How many times init method called if more then one instence are in servlet?

I have two questions how many times a method, modules or subroutines can be called? in most languages, how a variable is passed to a method?

Servlet life cycle?

The javax.servlet.Servlet interface defines the three methods known as life-cycle method. public void init(ServletConfig config) throws ServletException public void service( ServletRequest req, ServletResponse res) throws ServletException, IOException public void destroy() First the servlet is constructed, then initialized wih the init() method. Any request from client are handled initially by the service() method before delegating to the doXxx() methods in the case of HttpServlet. There are two more methods..... public abstract String getServletInfo() public abstract ServletConfig getServletConfig()

How do JSP methods get translated to Servlet methods?

A JSP gets converted into a Servlet for execution and hence the methods in a JSP are similar to the ones in a Servlet.Scriptlets and Expressions will end up in the body of doGet or doPostDeclarations will end up as instance variablesjspInit() and jspDestroy() will get translated to Servlet's init() and destroy() methods

Generic Servlet and HTTP Servlet?

javax.servlet.GenericServletSignature: public abstract class GenericServlet extends java.lang.Object implements Servlet, ServletConfig, java.io.SerializableGenericServlet defines a generic, protocol-independent servlet.GenericServlet gives a blueprint and makes writing servlet easier.GenericServlet provides simple versions of the lifecycle methods init and destroy and of the methods in the ServletConfig interface.GenericServlet implements the log method, declared in the ServletContext interface.To write a generic servlet, it is sufficient to override the abstract service method.javax.servlet.http.HttpServletSignature: public abstract class HttpServlet extends GenericServlet implements java.io.SerializableHttpServlet defines a HTTP protocol specific servlet.HttpServlet gives a blueprint for Http servlet and makes writing them easier.HttpServlet extends the GenericServlet and hence inherits the properties GenericServlet.

What method do you override to initialize instance variables in a JSP declaration?

jsp init()

Lifecycle diagram of applet in java?

IntroductionIn this Section you will learn about the lifecycle of an applet and different methods of an applet. Applet runs in the browser and its lifecycle method are called by JVM when it is loaded and destroyed. Here are the lifecycle methods of an Applet:init(): This method is called to initialized an appletstart(): This method is called after the initialization of the applet.stop(): This method can be called multiple times in the life cycle of an Applet.destroy(): This method is called only once in the life cycle of the applet when applet is destroyed.init () method: The life cycle of an applet is begin on that time when the applet is first loaded into the browser and called the init() method. The init() method is called only one time in the life cycle on an applet. The init() method is basically called to read the PARAM tag in the html file. The init () method retrieve the passed parameter through the PARAM tag of html file using get Parameter() method All the initialization such as initialization of variables and the objects like image, sound file are loaded in the init () method .After the initialization of the init() method user can interact with the Applet and mostly applet contains the init() method.Start () method: The start method of an applet is called after the initialization method init(). This method may be called multiples time when the Applet needs to be started or restarted. For Example if the user wants to return to the Applet, in this situation the start Method() of an Applet will be called by the web browser and the user will be back on the applet. In the start method user can interact within the applet.Stop () method: The stop() method can be called multiple times in the life cycle of applet like the start () method. Or should be called at least one time. There is only miner difference between the start() method and stop () method. For example the stop() method is called by the web browser on that time When the user leaves one applet to go another applet and the start() method is called on that time when the user wants to go back into the first program or Applet.destroy() method: The destroy() method is called only one time in the life cycle of Applet like init() method. This method is called only on that time when the browser needs to Shut down.

What is anatomy of java servlet?

A Servlets skeleton would look like below: /* * servlet name * * servlet description * All other stuff that is part of a Standard Class comment section */ //package declarations //import statements public class ServletName extends HttpServlet { // Instance Variables /** * Code to Initialize the Servlet */ public void init() throws ServletException { // Servlet Initialization Code goes here } /** * The Service Method * Gets invoked for every request submitted to the Servlet * This method is optional. We mostly use doGet, doPost Methods */ protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // Code for the Service Method goes here } /** * Process a GET request * */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { // Code for the doGet() method goes here } /** * Process a POST request * */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { // Code for the doPost() method goes here } /** * Process a PUT request * */ protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //Code for the doPut() method goes here } /** * You can have any number of methods for your processing * here. There is no limit as to the number of methods or * any restrictions on what you can name them. * Since this is all java code, you need to keep them * syntactically correct as per Java Coding Standards. */ /** * Clean-Up */ public void destroy() { // clean up activities before the Servlet is put to death } }

How do you write a servlet?

Servlet SkeletonIf I ask you, what are the components of a Java class, you'll happily tell me that, there are first package statements and then imports and then the class declaration. Within the class brackets, we have constructors, instance variables, methods etc. That was easy, wasn't it?The same way, every Servlet has a certain set of components that are mandatory for its well-being. (I just got carried away a bit) Or I must say, for its proper functioning.A Servlets skeleton would look like below:/** servlet name** servlet description* All other stuff that is part of a Standard Class comment section*///package declarations//import statementspublic class ServletName extends HttpServlet {// Instance Variables/*** Code to Initialize the Servlet*/public void init() throws ServletException{// Servlet Initialization Code goes here}/*** The Service Method* Gets invoked for every request submitted to the Servlet* This method is optional. We mostly use doGet, doPost Methods*/protected void service(HttpServletRequest req,HttpServletResponse resp)throws ServletException, IOException{// Code for the Service Method goes here}/*** Process a GET request**/protected void doGet(HttpServletRequest request,HttpServletResponse response)throws IOException, ServletException{// Code for the doGet() method goes here}/*** Process a POST request**/protected void doPost(HttpServletRequest request,HttpServletResponse response)throws IOException, ServletException{// Code for the doPost() method goes here}/*** Process a PUT request**/protected void doPut(HttpServletRequest req,HttpServletResponse resp)throws ServletException, IOException{//Code for the doPut() method goes here}/*** You can have any number of methods for your processing* here. There is no limit as to the number of methods or* any restrictions on what you can name them.* Since this is all java code, you need to keep them* syntactically correct as per Java Coding Standards.*//*** Clean-Up*/public void destroy(){// clean up activities before the Servlet is put to death}}The above is what a Servlets skeleton would look like

What method is used to retrieve the value associated to the parameter name provided within the init-param?

getServletConfig().getInitParameter(paramName);

Why do you use superclass init method inside your init method in a servlet?

Add your answer:

How do JSP methods get translated to Servlet methods?

What is servlet filtering?

Draw a flowchart to accept two numbers and display the sum of the numbers?

How do you get servlet context instance to servlet?

Describe the life cycle of servelet?

How does Apache httpd work?

How many times init method called if more then one instence are in servlet?

Servlet life cycle?

How do JSP methods get translated to Servlet methods?

Generic Servlet and HTTP Servlet?

What method do you override to initialize instance variables in a JSP declaration?

Lifecycle diagram of applet in java?

What is anatomy of java servlet?

How do you write a servlet?

What method is used to retrieve the value associated to the parameter name provided within the init-param?

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