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.
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.
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();
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?
The difference is that a GenericServlet has no defined protocol (it is "generic"), while HttpServler uses the HTTP protocol. HttpServlet is a subclass of GenericServlet with the purpose of creating a servlet for a web site.
Networking is a basic action. A servlet in Java is a single part of networking, a single task.
Servlet engines are software components that manage the execution of servlets, handling requests and responses, and providing an environment for servlets to run within a web server. In contrast, servlet chaining refers to the practice of invoking multiple servlets in a sequence, where the output of one servlet can be passed as input to another, allowing for modular and reusable components in web applications. Essentially, servlet engines provide the infrastructure, while servlet chaining is a design technique for enhancing functionality within that infrastructure.
ServletContext Defines a set of methods that a servlet uses to communicate with its servlet container.ServletConfig is a servlet configuration object used by a servlet container used to pass information to a servlet during initialization. All of its initialization parameters can ONLY be set in deployment descriptor.The ServletContext object is contained within the ServletConfig object, which the Web server provides the servlet when the servlet is initialized.You can specify param-value pairs for ServletContext object in tags in web.xml file.The ServletConfig parameters are specified for a particular servlet and are unknown to other servlets. The ServletContext parameters are specified for an entire application outside of any particular servlet and are available to all the servlets within that application.By Santanu
request.getAttribute() is used on the Server side Java code to get values submitted from the form onto the Servlet or other java classes request.getParameter() is used on the JSP page to get values sent by the servlet and display it in the jsp page
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.
In send Redirect whenever the client makes any request it goes to the container, there the container decides whether the concerned servlet can handle the request or not. If not then the servlet decides that the request can be handle by other servlet or jsp. Then the servlet calls the sendRedirect() method of the response object and sends back the response to the browser along with the status code. Then the browser sees the status code and look for that servlet which can now handle the request. Again the browser makes a new request, but with the name of that servlet which can now handle the request and the result will be displayed to you by the browser. In all this process the client is unaware of the processing.
Http servlet and Generic servlet
You cannot. HTML is a static file and it cannot interact with a Java Servlet. A Servlet can always redirect to a HTML page but the other way round cannot happen.
Applet: It is run on browser, i mean client side. Servlet: It is run on server, i mean server side.
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.
To configure servlet chaining, you need to set up multiple servlets in your web application, typically defined in the web.xml file or through annotations. Each servlet processes requests and can forward the response to the next servlet in the chain using the RequestDispatcher's forward() method. Ensure that each servlet is mapped to a specific URL pattern, allowing the initial request to reach the first servlet in the chain. Additionally, manage the flow by handling request attributes to pass data between servlets as needed.