Server - An overview

Sure! Let’s explore servers in detail, especially in the context of web development and Java applications.

🖥️ What is a Server?

A server is a computer or software that provides services or resources to other computers, known as clients, over a network.

🧩 Types of Servers (Conceptual Classification)

Server Type	Description
Web Server	Serves static content (HTML, CSS, JS), handles HTTP requests
Application Server	Runs application logic (Java EE, .NET apps), manages business logic
Database Server	Stores and manages databases (PostgreSQL, MySQL, Oracle)
File Server	Shares files over a network
Mail Server	Sends, receives, stores email
Proxy Server	Acts as a gateway between client and server
DNS Server	Resolves domain names to IP addresses
Game Server	Hosts multiplayer games, synchronizes player data

🧠 How a Web Server Works (HTTP-based)

Client (Browser) sends an HTTP request to the server.
Server processes the request.
Returns an HTTP response (HTML, JSON, etc.) to the client.
The browser renders the response.

🔧 Web Server vs Application Server

Feature	Web Server (e.g., Apache HTTPD, Nginx)	Application Server (e.g., Tomcat, WildFly)
Serves Static Content	✅ Yes	❌ No (usually not efficient for static)
Business Logic	❌ No	✅ Yes
Protocols	HTTP, HTTPS	HTTP, RMI, JMS, SOAP, etc.
Example Use Case	Hosting static websites	Running dynamic Java-based web apps

⚙️ Common Java-Based Servers

🔹 Apache Tomcat (Web + Servlet Container)

Lightweight
Supports Servlets, JSP
Default in Spring Boot

🔹 GlassFish / Payara (Full Java EE)

Supports EJB, JPA, JTA, JMS
Suitable for enterprise systems

🔹 WildFly (formerly JBoss)

Robust, full-featured Java EE app server
Modular and fast

🔹 Jetty

Lightweight, embeddable in applications
Used in Maven, Eclipse

🔹 WebLogic (Oracle) & WebSphere (IBM)

Full-featured, enterprise-grade
Expensive, used in big organizations

🔌 Embedded vs Standalone Servers

Type	Description
Standalone	Installed separately (Tomcat, WildFly). Deploy WAR files manually.
Embedded	Comes bundled with your app (like Spring Boot + embedded Tomcat). Run via `main()`.

🌐 Server Deployment Models

1. On-Premise

You manage the hardware and install server software
Total control but high maintenance

2. Cloud Servers

Hosted on cloud platforms (AWS, Azure, GCP)
Scalable, flexible, pay-as-you-go

3. Containerized Servers

Run in Docker containers (e.g., docker run tomcat)
Easily portable and isolated

4. Serverless (for specific cases)

No need to manage infrastructure (e.g., AWS Lambda)
Not used for full Java EE applications

📂 Java Server Architecture (Typical Web App)

Client (Browser/Mobile)
     ↓
Web Server (e.g., Apache HTTPD or Nginx)
     ↓
Application Server (e.g., Tomcat or WildFly)
     ↓
Business Logic (Java EE / Spring)
     ↓
Database Server (e.g., PostgreSQL, MySQL)

🔐 Servers and Security

Use HTTPS instead of HTTP
Enable firewalls and reverse proxies
Secure APIs with OAuth/JWT
Keep servers updated with patches

📦 Summary Table

Server	Type	Java EE Support	Use Case
Tomcat	Servlet Container	❌ Limited	Spring Boot, simple Java web apps
Jetty	Servlet Container	❌ Limited	Lightweight, embeddable
GlassFish	App Server	✅ Full	Java EE apps, learning
WildFly	App Server	✅ Full	Enterprise Java apps
Payara	App Server	✅ Full	Stable fork of GlassFish
WebLogic	App Server	✅ Full	Banking, government, enterprise
Nginx/Apache	Web Server	❌ No	Front-end static content, load balancing