What Is Tomcat?

Tomcat is essentially a Java servlet container. This means it handles Java servlets and JSP (JavaServer Pages), allowing Java applications to be deployed on a web server.

Unlike full-fledged Java EE (Jakarta EE) application servers like WildFly or GlassFish, Tomcat focuses mainly on servlet and JSP execution, making it lighter and more efficient for many web applications.

It supports:

• Servlet API (Jakarta Servlet)
• JSP (JavaServer Pages)
• WebSockets
• Security and authentication mechanisms
• Connection pooling for databases

Why Use Tomcat?

So, why should you use Tomcat over something else? Here are some key reasons:

1. Lightweight & Fast
   Unlike full Java EE application servers, Tomcat has a minimal footprint.

2. Easy to Deploy
   You can deploy a .war file (Web Application Archive) by simply dropping it into the webapps directory.

3. Widely Used & Supported
   Since Tomcat is developed under the Apache Foundation, it has a huge community and strong support.

4. Cross-Platform
   Tomcat runs on Windows, macOS, Linux, and even in cloud environments with minimal configuration.

5. Security Features
   Tomcat includes authentication, SSL support, and access control configurations.

Tomcat Architecture: How It Works

Tomcat follows a modular architecture, and its core components include:

1. Catalina (Servlet Container)

Catalina is Tomcat’s servlet engine, responsible for handling requests and executing servlets. Think of it as the “brain” of Tomcat.

2. Coyote (HTTP Connector)

Coyote acts as the web server, handling HTTP requests and responses. It allows Tomcat to function as a standalone web server.

3. Jasper (JSP Engine)

Jasper processes JSP files, converting them into servlets, which can then be executed by Catalina.

4. Cluster & High Availability

Tomcat supports clustering, meaning multiple Tomcat instances can work together to ensure high availability and scalability.

Installing and Running Tomcat

1. Download Tomcat

• Go to Tomcat’s official website and download the latest stable release.

2. Extract & Configure

• Extract the downloaded archive and navigate to the bin directory.

3. Start Tomcat

• On Windows: Run

  1	startup.bat

• On macOS/Linux: Run

  1	./startup.sh

After starting, Tomcat should be accessible at:
http://localhost:8080

Deploying a Web Application

To deploy a Java web app:

1. Place the .war file inside the webapps/ directory.
2. Tomcat will automatically detect and deploy the application.
3. Access it via: