What is application

An application refers to a program or software designed to perform specific tasks for users. Applications can range from simple tools like calculators to complex systems such as enterprise resource management platforms.

Types of Applications

1. Stand alone Applications:
   • Programs installed on personal computers or laptops ,runs in the local disk results re not sharable .
2. Distributed Applications:
   • Apps that run in a web browser and are hosted on servers , whose results are sharable across the world.
   • Example all internet based application are known as distributed applications like yahoo, gmail , facebook, instagram .

To develop distributed application we use a language called java and java comes under internet software. Architecture required for development of distributed application , programmer must use a well known Architecture known as client server architecture .

• 2-Tier Architecture
• 3-Tier Architecture
• n-Tire Architecture

2-Tier Architecture

Two tier Architecture it contains client and server side programing .

3-Tier Architecture

Three tier architecture it contains client , server program and database software

n-Tier Architecture

n tire architecture it contains client program , fire wall program(security program) , server side program and database software .

Client always makes a request to the server to get the services from server . Server which receives client request passes the client request and gives response back to client concurrently .

Fire wall

A firewall is a security system—either hardware, software, or both—that monitors and controls incoming and outgoing network traffic based on predetermined security rules. Its main purpose is to protect networks, devices, or systems from unauthorized access, cyberattacks, and other threats by creating a barrier between trusted and untrusted networks.

How a Firewall Works

1. Monitoring Network Traffic:
   • A firewall examines data packets traveling through the network.
2. Filtering:
   • Firewalls use rules to determine which traffic is permitted or denied, ensuring only safe traffic reaches the protected system.

Server

Types of Servers

1. Web Server:
   • Hosts websites and serves web pages to users via browsers.
   • Example: Apache, NGINX.
2. Database Server:
   • Stores and manages data, allowing clients to perform queries or retrieve information.
   • Example: MySQL, SQL Server.
3. File Server:
   • Provides shared storage for files and allows clients to access or transfer them.
   • Example: Network Attached Storage (NAS).
4. Application Server:
   • Hosts and runs applications, providing functionality to users or other applications.
   • Example: Glassfish, Tomcat