Introduction to Web Applications

• A web application can be understood as a software program that operates on a server rather than on an individual device.
• Users access these applications via a web browser, such as Chrome or Firefox, by entering a specific website URL. For instance, when you make an online hotel reservation, you are utilizing a web application.
• These applications enable users to engage with the server to execute various tasks for example ticket booking.

Essential Components of a Java Web Application

1. java Development Kit (JDK):
   • The JDK is your essential toolkit for developing and running Java applications. It includes all the tools you need to build and test Java software.
2. Web Server:
   • A web server acts like a waiter in a restaurant. It receives requests from your browser (like “show me available hotel rooms”) and delivers the response (such as a list of rooms). Apache Tomcat is a popular option.
3. Servlets:
   • Servlets are small Java programs that operate on the server to manage user requests. For instance, when you click “Search,” a servlet processes that request and retrieves the results.
4. JSP (JavaServer Pages):
   • JSP is used to create web pages that mix HTML (the layout of the page) with Java code. This allows for dynamic content, such as displaying different room prices based on what’s available.
5. Database
   • A database is where all the data is kept, such as customer information or room reservations. Common databases include MySQL, PostgreSQL, and Oracle.
6. Web Container:
   • A web container is a component of the web server that oversees servlets and JSPs. It ensures everything operates smoothly by managing tasks like security and directing requests to the right servlet or JSP. Think of it as the organizer of the Java elements in your web application.

How These Components Work Together

Picture this: you’re trying to book a hotel room on the internet.

1. First, you open your web browser and enter the hotel website’s address.
2. Then, the web server gets your request.
3. Next, the web container looks for the right servlet to handle what you need.
4. After that, the servlet talks to the database to find out which rooms are free.
5. Finally, the information comes back to you as a web page made with JSP.

        🌐 Open Web Browser and Enter Hotel Website's Address:
        You start by opening your web browser (like Chrome, Firefox, etc.) 
        and entering the hotel website's address (URL).
            │
            ▼
        📡 Web Server Receives Your Request:
        The web server (like Apache Tomcat) receives your request and starts processing it.
            - The web server acts like a waiter in a restaurant. 
              It takes your request (e.g., "show me available hotel rooms") and passes it to the web container.
            │
            ▼
        📦 Web Container Finds the Right Servlet:
        The web container is part of the web server that manages servlets and JSPs.
            - It looks for the appropriate servlet to handle your request. 
              A servlet is a small Java program that processes requests and generates responses.
            │
            ▼
        📨 Servlet Talks to the Database to Check Room Availability:
        The servlet communicates with the database (like MySQL) to check for 
        room availability and fetches the necessary data.
            - The servlet sends a query to the database to get information about available rooms.
            - The database stores all the information, like customer details and room bookings.
            │
            ▼
        🏨 Information Comes Back as a Web Page Made with JSP:
        The servlet sends the data to a JSP (JavaServer Page), which combines HTML and Java code
        to create a dynamic web page with the information you requested.
            - JSP is used to create web pages that combine HTML (the structure of the page) 
              with Java code. It allows dynamic content to be displayed, 
              like showing different room prices based on availability.
            │
            ▼
        🖥 Displayed in Your Web Browser:
        Finally, the web page is sent back to your web browser, where you can view 
        the available rooms and proceed with your booking.
            - The client-side (front-end) interacts with the user directly through the web browser 
              using technologies like HTML, CSS, and JavaScript.
    

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