Summary Servlet and Web Container Architecture

Web Containers

Sure, I'd be happy to help! I understand that you want a summary of the "Chapter: Servlets and Web
Container Architecture" that is engaging, easy to understand, and includes examples and visuals. I'll do
my best to incorporate those elements in this summary. What is a Servlet? In the world of web
development, a servlet is a Java class that runs in a web container and provides a response to a client's
request. Servlets are a key component of Java-based web applications and are used to process requests
and generate dynamic content. Web Container Architecture At a high level, a web container is a
component of a web server that manages the lifecycle of servlets. When a client makes a request to a
web application, the web container receives the request and routes it to the appropriate servlet for
handling. Here's a simple diagram that illustrates the flow of a request in a web container: Client
(Browser) --> Web Server (e.g. Apache Tomcat) --> Web Container (e.g. Catalina) --> Servlet Example:
Step-by-Step Calculation To make this concept more concrete, let's consider a simple example of a
servlet that performs a step-by-step calculation. Suppose we want to create a servlet that takes two
numbers and an operation (addition, subtraction, multiplication, or division) as input and returns the
result. Here's what the code for the servlet might look like:

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;



@WebServlet("/calculator")

public class CalculatorServlet extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {

// Get input values from the request

double num1 = Double.parseDouble(request.getParameter("num1"));

double num2 = Double.parseDouble(request.getParameter("num2"));

String operation = request.getParameter("operation");

, // Perform calculation based on the operation

double result = 0;

switch (operation) {

case "add":

result = num1 + num2;

break;

case "subtract":

result = num1 - num2;

break;

case "multiply":

result = num1 * num2;

break;

case "divide":

if (num2 == 0) {

throw new ServletException("Cannot divide by zero");

}

result = num1 / num2;

break;

default:

throw new ServletException("Invalid operation");

}



// Set the result in the request attribute

request.setAttribute("result", result);