Roles of User, Browser, Webserver, and Backend Services in a Web Application

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 DIAGRAM

THEORY

MAP

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1.2 User

  • Definition

  • Role of User

1.3 Browser

  • Definition

  • Roles of Browser

  • Browser to Web Server Communication

  • Types of Requests

    • GET Request

    • POST Request

    • AJAX Request

  • Difference Between GET and POST

  • Common Browsers

  • Rendering the Browser View

  • Types of Files Handled by Browser

  • User Interaction Through Browser

1.4 Web Server

  • Definition

  • Popular web servers include

  • Functions of Web Server

1.4.1 Apache

1.4.2 IIS

  • Differences Between Apache and IIS

1.5 Backend Services

  • Definition

  • Role of Backend Services

1.2 User

Definition:

The User is an essential part of the web development framework. The user interacts with the application and defines the requirements and expectations that the website must fulfill.

Role of User:

  • The user’s expectations determine the design and development of the website.

  • Users prefer websites that are efficient, easy to use, and behave similarly to the applications on their computers and mobile devices.

  • The user interacts with the browser using input devices such as:

    • Mouse and keyboard on PCs.

    • Swipes and taps on mobile devices.

  • The web framework processes this user input and generates the required visual output on the browser.

Thus, the user provides input and expects a smooth, application-like experience through the browser.



1.3 Browser

Definition:
The Browser is an application that allows the user to access and interact with websites. It acts as a bridge between the user and the web server.

Roles of Browser:

  1. Provides communication between the user and the web server.

  2. Interprets the data received from the server and shows the visual output.

  3. Handles user interaction through devices such as keyboard, mouse, or touchscreen and takes appropriate action.

Browser to Web Server Communication:

  • The browser uses the HTTP and HTTPS protocols to communicate with the web server.

    • HTTP (Hyper Text Transfer Protocol) is a request/response protocol.

    • HTTP specifies the types and formats of requests and responses.

    • HTTPS is similar to HTTP but includes an additional security layer so the user can choose whether to accept the secure connection.

Types of Requests:

  • GET Request:

    • Used to retrieve data like HTML files or images from the server.

  • POST Request:

    • Used to send data to the server, such as credit card details during shopping.

  • AJAX Request:

    • AJAX (Asynchronous JavaScript and XML) allows GET or POST requests directly through JavaScript running in the browser.

Difference Between GET and POST:

  • In GET, the request appears in the URL string.

  • In POST, the submitted data does not appear in the URL.

Common Browsers:

  • Internet Explorer

  • Mozilla Firefox

  • Google Chrome

  • Safari

Rendering the Browser View:

  • The browser reads the initial URL and renders the HTML document to create the DOM (Document Object Model).

  • The DOM is a tree-structured object, and the browser interprets each element to display the web page.

  • The browser collects data from multiple server requests to build the page.

Types of Files Handled by Browser:

  • HTML files: Represent static data.

  • CSS files: Define page styling such as fonts, colors, and borders.

  • Client-side scripts: JavaScript files add functionality and interactivity.

  • Media files: Include images, videos, and audio.

  • Data files: XML, JSON, or raw text are used, especially in AJAX responses.

  • HTTP headers: Define the data type of requests and responses.

User Interaction Through Browser:

  • The browser captures user events like mouse clicks, keyboard input, or touch events.

  • Based on these events, the browser performs actions such as loading a web page or showing a pop-up menu.

1.4 Web Server

Definition:
A Web Server is a special server where the browser submits requests for web pages or web applications.

Popular web servers include:

  • Apache

  • IIS (Internet Information Services) by Microsoft

Functions of Web Server:

  1. Accepts requests from web browsers.

  2. Processes the user request.

  3. Responds by providing the requested services.

  4. Serves web-based applications.

  5. Uses DNS (Domain Name System) to translate domain names into IP addresses.

  6. Verifies the requested address, finds files, runs scripts, exchanges cookies, and sends the response to the browser.

  7. Supports session handling techniques.

1.4.1 Apache

  • Apache Web Server is popular because of its reliability and efficiency.

  • It is open-source software, meaning it is freely available.

  • Works best on UNIX systems, but also runs on Windows.

  • Configured using the httpd.conf file in the Apache package.

1.4.2 IIS

  • Internet Information Services (IIS) is a web server provided by Microsoft.

  • Commonly used on Windows platforms.

Differences Between Apache and IIS:

FeatureApache Web ServerIIS Web Server
PlatformWorks on UNIX and Windows  Works only on Windows
LicensingOpen source Vendor specific
Configuration Through httpd.conf file  Through IIS snap-in under Control Panel

1.5 Backend Services

Definition:
Backend services are processes running behind the web server that provide data requested by the browser.

Role of Backend Services:

  • The backend services, such as databases, store the website’s data.

  • When the browser requests data:

    • The web server connects to the backend service or database.

    • Retrieves the data, formats it, and sends it to the browser.

  • When the browser sends data:

    • The web server updates the data in the backend service.

 Roles of Components in a Web Application

ComponentRole
UserInteracts with the system using input devices; defines expectations.

BrowserConnects user and server; renders data; handles user input and output.

Web ServerProcesses browser requests; communicates with backend services; serves web content.

Backend ServicesProvides and updates data behind the scenes; supports server with required data.





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