Web Server

A web server is a piece of software (and often the hardware it runs on) that serves web pages to users upon request.

Here’s how it works:

• Receives Requests: When you type a URL in your browser and hit enter, your browser sends a request to a web server.

• Processes Requests: The web server processes this request. If it’s a request for a static file like an HTML page, image, or CSS file, the web server finds the file and sends it back to the browser.

• Responds: The browser receives the file and displays it to you. Common web servers include Apache, Nginx, and Microsoft’s Internet Information Services (IIS).

Application Server

An application server is more complex. It does everything a web server does, but it also provides additional functionality needed to run dynamic applications.

Here's a simple explanation:

• Handles Business Logic: An application server can process business logic. This means it can take user input, process it (e.g., access a database, perform calculations), and generate dynamic content.

• Integrates with Databases: It can communicate with databases to fetch and store data as needed by the application.
  Supports Various Protocols: While a web server typically uses HTTP/HTTPS, an application server might support other protocols like RMI (Remote Method Invocation), JMS (Java Message Service), etc.

• Middleware Services: It often provides services like transaction management, messaging, and security which are essential for enterprise applications. Common application servers include Apache Tomcat, JBoss, WebSphere, and WebLogic.

Differences Between Web Server and Application Server

1. Purpose:

Web Server: Serves static content (like HTML, CSS, JavaScript, images). Application Server: Handles dynamic content and business logic (like processing data from databases and generating responses).

2.Functionality:

Web Server: Limited to handling HTTP requests and responses. Application Server: Provides additional services such as data processing, transaction management, and messaging.

3.Content:

Web Server: Ideal for serving static content directly. Application Server: Suitable for generating and serving dynamic content, typically interacting with databases and other services.

4.Complexity:

Web Server: Simpler and generally faster for static content delivery. Application Server: More complex due to the need to handle application logic and various services.

5.Examples:

Web Server: Apache HTTP Server, Nginx, IIS. Application Server: Apache Tomcat (also acts as a web server), JBoss, WebSphere, WebLogic.

Simplified Analogy

Think of a web server as a library. When you request a book (static content), the librarian (web server) finds it on the shelf and hands it to you.

An application server is like a restaurant kitchen. When you place an order (dynamic request), the chefs (application server) have to prepare the dish (process business logic), possibly fetching ingredients from the fridge (database) and cooking it (data processing), before serving it to you.

By understanding these roles, you can better appreciate how web applications function and the importance of each type of server in delivering web content and services.