TuxCare Blog

Introduction to Apache Tomcat: A Beginner’s Guide

by Rohan Timalsina

October 25, 2024 - TuxCare expert team

Apache Tomcat is an open-source web server and servlet container for Java applications.
It supports servlets, JSPs, session management, security features, and scalability.
TuxCare’s Endless Lifecycle Support (ELS) offers automated vulnerability patches for Tomcat and other critical packages on end-of-life Linux distributions.

Apache Tomcat, often referred to as just Tomcat, is a widely used open-source Java application server that serves as a core component in enterprise IT infrastructure. Its lightweight, flexible, and open-source nature make it an ideal choice for developers and organizations looking to run Java-based web applications.

This article provides an in-depth overview of Tomcat, its key functionalities, its history, and why it’s a leading choice in the Java ecosystem. We’ll also discuss how you can secure Tomcat deployments in end-of-life Linux systems using extended support options.

What Is Apache Tomcat?

Apache Tomcat is a Java servlet container that implements the Java Servlet, JavaServer Pages (JSP), WebSocket, and Java Expression Language (EL) specifications. It provides a streamlined environment for developers to create dynamic web applications using Java.

As a reference implementation, Tomcat ensures compatibility with Java EE standards and offers a robust platform for building scalable and reliable web applications. Its built-in features, such as session management, security, and connection pooling, simplify common development tasks.

Tomcat is widely used in various industries, from small startups to large enterprises, and is compatible with popular frameworks like Spring and Struts. Whether you’re building a simple web service or a complex enterprise application, Tomcat provides a solid foundation for Java-based web development.

History and Evolution of Apache Tomcat

Apache Tomcat has a long history of releases, dating back to 1999 when it was first launched as version 3.0 under the Apache Software Foundation. Over the past two decades, numerous major and minor versions have been released, each adding new features and improving performance while maintaining backward compatibility.

It follows a defined support lifecycle with each major release receiving updates for approximately 10 years. Older versions such as Tomcat 7 are now end-of-life, while newer releases like Tomcat 10.1 and 11.0 continue to evolve with support for the latest Jakarta EE specifications.

Here are some key milestones in Tomcat’s development:

Tomcat 4.1: Introduced support for Servlet 2.3 and JSP 1.2.
Tomcat 5.0: Brought forward Servlet 2.4 and JSP 2.0 specifications, with improvements in session management and performance.
Tomcat 6.0: Marked the adoption of Servlet 2.5 and JSP 2.1, adding enhanced management and monitoring capabilities.
Tomcat 7.0: Integrated Servlet 3.0, JSP 2.2, bringing support for asynchronous processing.
Tomcat 8.0: Introduced Servlet 3.1, WebSocket 1.0, and JSP 2.3.
Tomcat 9.0: Implemented Servlet 4.0, with support for HTTP/2.
Tomcat 10.0 and beyond: Supports Jakarta Servlet 5.0, reflecting the transfer of Java EE to the Eclipse Foundation under the name Jakarta EE.

The latest stable release at the time of writing is Tomcat 10.1.31, which was released on October 3, 2024. Before choosing a version, it is important to ensure that the version you select aligns with the Servlet and JSP versions required by your application. For instance, if your application relies on Servlet 3.1 features, you would use Tomcat 8 or later.

How Does Tomcat Work?

Apache Tomcat is a Java application which operates using a component-based architecture. This architecture consists of the following key components:

Connector: The connector handles incoming HTTP requests and determines the appropriate container based on the request’s context path. It then passes the request to the container for processing.

Container: The container is responsible for processing the request, including executing servlets, JSPs, and other web components, handling sessions, and managing security. It also generates the response to be sent back to the user.

Engine: The engine is the top-level component that coordinates the overall request processing and manages the lifecycle of web applications deployed on Tomcat.

When a user requests a web page from a Tomcat-powered application, the connector receives the request. It then delegates the request to the appropriate container, which processes the request and generates a response. The response is then sent back to the user through the connector.

Alternatives to Apache Tomcat

Although Tomcat is popular there are several alternatives available that also serve as servlet containers or Java application servers. Some of them include:

Jetty: Another lightweight open-source servlet container that is often used in embedded Java applications. Known for its small footprint and flexibility, Jetty is well-suited for scenarios where a minimal and efficient server is required.

WildFly (formerly JBoss): A full Java EE application server that provides a comprehensive set of features for building enterprise-grade applications. WildFly offers a balance between performance and functionality, making it a suitable choice for various use cases.

WebSphere and WebLogic: Full Java EE-compliant application servers offered by IBM and Oracle, respectively. These commercial options often come with significant licensing fees and are typically used in large enterprise environments that require advanced features and support.

Other notable alternatives include GlassFish, another open-source Java EE application server, and TomEE, a Tomcat-based Java EE application server that combines the performance and simplicity of Tomcat with the features of Java EE.

Why Use Apache Tomcat?

Apache Tomcat is preferred for a number of reasons:

Lightweight and Efficient: Compared to full-fledged Java EE application servers, Tomcat offers a leaner and more efficient environment, making it ideal for applications that don’t require the entire Java EE stack. It does not come with all the overhead of Java EE features, allowing for faster startup times and lower resource consumption.

Excellent Performance: Tomcat offers excellent performance, especially for applications that primarily use servlets and JSP. It is designed to handle large volumes of traffic with minimal resource usage, making it a suitable choice for high-performance web applications.

Flexibility and Customization: Tomcat supports a wide variety of configurations, including different connectors, servlet engines, and deployment options. Additionally, its compatibility with popular frameworks like Spring and Struts, allows developers to tailor it to specific project needs.

Strong Community Support: As an open-source project, Tomcat benefits from a large and active community that provides regular updates, bug fixes, and enhancements. Its extensive documentation, user forums, and third-party resources make it easy to learn and use.

Security Features: Tomcat’s role in the Java Servlet specification ensures its reliability and adherence to industry standards. Additionally, its built-in security features, such as SSL/TLS support, contribute to a secure and robust application environment.

Securing Apache Tomcat on End-of-Life Linux Systems with TuxCare

When running Apache Tomcat on Linux systems that have reached their end-of-life (EOL), ensuring ongoing security becomes a significant challenge. When an operating system reaches EOL, it no longer receives official security updates, leaving it wide open to exploitation. Attackers often target vulnerabilities in software running on outdated systems, and without any security updates, your Tomcat deployment is at risk.

To address this, TuxCare’s Endless Lifecycle Support (ELS) offers a solution by providing automated vulnerability patches for up to four years beyond an EOL date. It includes critical security updates for over 140 packages, covering Linux kernel, Apache Tomcat, Apache HTTP Server, PHP, MySQL, OpenSSL, and more. This ensures that your EOL Linux systems remain safe from new vulnerabilities while giving your organization the time it needs to plan a proper migration.

With TuxCare’s ELS, organizations can continue to leverage Tomcat on end-of-life Linux distributions without compromising security. TuxCare currently supports the following Linux distributions: CentOS 6, CentOS 7, CentOS 8, CentOS Stream 8, Oracle Linux 6, Oracle Linux 7, Ubuntu 16.04, and Ubuntu 18.04

For more information on Tomcat vulnerabilities and patch availability for different Linux distributions, visit TuxCare’s CVE tracker.

Final Thoughts

Apache Tomcat remains a powerful and efficient tool for deploying Java-based web applications, offering flexibility, performance, and ease of use. However, it’s crucial to prioritize ongoing security updates to protect your deployments from emerging vulnerabilities.

This is where TuxCare’s Endless Lifecycle Support (ELS) becomes essential. ELS ensures that your Tomcat deployment remains secure on outdated Linux systems by providing automated security updates for years after the official end-of-life date. By protecting your system from vulnerabilities, TuxCare can help reduce the risk of data breaches and system downtime, giving you peace of mind and allowing you to continue operations while planning for future upgrades.

In addition to ELS, TuxCare offers SecureChain for Java, which provides access to a single trusted repository of vetted Java packages and libraries to ensure your applications remain secure and free from vulnerabilities.

Worried about the security of your end-of-life Linux systems? Our Linux security experts are here to help. Ask a question to learn how TuxCare’s Endless Lifecycle Support can keep your workloads secure.

Explore More:

The Risks of Running an End Of Life OS – And How To Manage It

The Secure Java Developer’s Toolkit

Supply Chain Attacks: A Java Dependency Nightmare that Became a Reality

Securing Your Java Supply Chain

Navigating the Challenges of Upgrading from Spring Framework

Web Server vs. Application Server: A Comprehensive Comparison

Live Patching as a Growth Enabler for Your Infrastructure

Summary