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Each web application contains a Session that can contain data that can be commonly made available to all the parts of the web application. The Session can be accessed from both the JSP and the Servlet.
Ex:
The servlet contains references to the HttpRequest object. So to access the session you can do so as below:
HttpSession session = request.getSession();
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What is difference between single threaded servlet and multi threaded servlet?
The single thread model means that your servlet would not be multi-threaded. If there are two concurrent requests to your servlet then 2 instances of your servlet will be created to process these 2 requests. You can implement the single thread model by implementing the SingleThreadModel interface in your class. This is just a marker interface and does not have any methods. The multi threaded model means that your servlet would be multi-threaded and only one instance would exist. Multiple concurrent requests would be served by the same instance but in different threads. You can implement the multi threaded model by not implementing the SingleThreadModel interface in your servlet class.
Difference between temporary servlet and permanent servlet?
A temporary servlet is started when a request arrives and shut down after the response is generated. A permanent servlet is loaded when the server is started and lives until the server is shut down. * This is useful when startup costs are high, such as a servlet that establishes a connection to a database. * Also useful for permanent serverside service, such as an RMI server. * Provides faster response to client requests when this is crucial. Being temporary or permanent is part of the server configuration.
What company uses a ten digit tracking number?
DHL and aramex.
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?
How many digits in a fed ex tracking number?
How many digits in a fed referemce number?
What is servlet and why it is used?
servlet is a small program which run on serverside,and it can not be downloaded at client side. java servlets dynamically extends the functionalities of a web server. main use is: session tracking: no of users (unique) visited u'r website. in order to use cookies..
How many scope are there in servlet?
The two scopes are: Request & Session
How is statelessness of http overcome to run e-commerce applications on web?
it can be overcome by implementing session tracking & management in the running program on the server side. There are four solutions 1. Cookies, 2. Hidden from field, 3. URL rewriting and 4.Servlet Session API
What is session in jsp?
Session in the JSP and Servlet context refers to an instance of the HttpSession object that contains all the information about the current user session with the web application. This can be used as a cache or temporary storage area to store values that might be required across the application.
Set and get session attributes syntax in servlets and java script?
Setting and getting session attributes is fairly easy. It is the same in both Servlets and JSPs with one exception. In a JSP, you already have access to the session object, and you do not have to declare it. In a Servlet, you must get the session like this: javax.servlet.http.HttpSession session = request.getSession(); Once you have done that, you can set a session object like this: session.setAttribute("name","value"); To retrieve the value, do this: String foo = (String) session.getAttribute("name"); A couple of things to keep in mind: * The second parameter in the setAttribute method is an Object, not a String. When you retrieve the value, you have to cast it. In the example above, I am casting it to a String. * If you try to perform a getAttribute on a session attribute that does not exist, or was not set, it will return a null. * Session attributes are not available using JavaScript. You can not set or get an attribute in JavaScript. * You do NOT need to do the 'session = request.getSession() in a JSP. It is only necessary in a Servlet.
What are types of servlet?
Http servlet and Generic servlet
What is java servlet chaining?
Servlet Chaining means the output of one servlet act as a input to another servlet. Servlet Aliasing allows us to invoke more than one servlet in sequence when the URL is opened with a common servlet alias. The output from first Servlet is sent as input to other Servlet and so on. The Output from the last Servlet is sent back to the browser. The entire process is called Servlet Chaining.
Can insert javascript coding in servlet?
No. Javascript code can be present inside a JSP but not inside a servlet. A Servlet is a pure java class.
What is servlet mapping?
A Servlet Mapping is a directive in the web.xml that tells the Servlet Container which class to use when a particular Servlet is called. A Servlet is a class within your Java Web Application. Let's say you have a servlet called MyServlet in the com.example.servlet package. You would need to have a Servlet Mapping pointing the path "/MyServlet" to the "com.example.servlet.MyServlet" class. Without the servlet mapping, you would not be able to invoke your servlet because the Servlet container would not know where it is. JSPs are different - they do not need mappings like this. JSPs exist within the WebRoot of the application, so they are always available. Servlets exist in the WEB-INF\Classes directory once your application is deployed.
How the pass value from the HTML pages to the servlet?
You need a form to pass value to a servlet. In the form tag, the action element passes the value into the servlet.
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/
What is a session What are the different ways of session tracking in servlet programming?
In servlet programming, a session is a way to maintain state between multiple requests from the same client. There are several ways to track sessions in servlet programming, including cookies, URL rewriting, and hidden form fields. Cookies are the most commonly used method, where a unique identifier is stored on the client's browser to associate subsequent requests with the same session. URL rewriting involves appending session IDs to URLs, while hidden form fields store session IDs in HTML forms.
