Everything you need to know about Tomcat: The high-availability Java and Jakarta EE application server for servlets, JSP, and WebSockets.
Apache Tomcat is a long-standing, open-source Java servlet container known for its robust implementation of core Java enterprise specifications. Initially released by the Apache Software Foundation in 1998, Tomcat was introduced just four years after the inception of Java itself. It was originally designed as the reference implementation for the Java Servlet API and JavaServer Pages (JSP) specification. Over the years, it has evolved into a widely used application server with a reputation for stability and extensibility.
Tomcat and Jakarta EE
Tomcat’s evolution reflects the broader changes in Java enterprise technologies. Originally based on Java EE (Enterprise Edition), Tomcat has transitioned to the Jakarta EE specification. Tomcat 9 and earlier versions were aligned with Java EE, while Tomcat 10 and subsequent releases conform to the Jakarta EE standards. This shift is significant due to the change in package names from javax.* to jakarta.*. The current version, as of this writing, is Tomcat 10.0.23, which supports this updated package naming convention.
Tomcat’s Role and Functionality
Tomcat serves as both a servlet container and a web server. In its role as a servlet container, Tomcat implements the Jakarta Servlet specification, which is essential for hosting servlets. Servlets are Java programs that run on a server and handle client requests and responses. Tomcat also supports the Jakarta Server Pages (JSP) specification, enabling the creation of dynamic web content using JSP technology.
While Tomcat can function as a web server by serving static files from the local system, its primary role is to act as a servlet container. It differs from a full Java EE application server, which typically provides a more extensive set of features, including EJBs (Enterprise JavaBeans) and JPA (Java Persistence API). Tomcat focuses on providing a reliable environment for servlets and JSPs, often integrating with other tools to deliver additional functionality.
Deployment and Usage
Tomcat supports several methods for deploying Java applications. Developers can deploy applications using WAR (Web Application Archive) files, which encapsulate all the components of a web application. Tomcat also allows for the deployment of exploded directories, which are directories containing the unarchived files of a WAR. Another deployment method is through the Tomcat Manager application, which provides a web interface for managing applications and server settings.
Advantages of Tomcat
One of Tomcat’s key advantages is its simplicity and ease of use. It offers a lightweight solution for hosting Java web applications, which is particularly appealing for projects that do not require the full breadth of Java EE features. Tomcat’s extensive documentation, active community, and regular updates contribute to its popularity and reliability. It is often chosen for its performance, scalability, and the ability to integrate seamlessly with various development tools and frameworks.
Conclusion
In summary, Apache Tomcat remains a pivotal component of the Java ecosystem, providing a tried-and-true environment for running Java web applications. Its transition from Java EE to Jakarta EE reflects the ongoing evolution of Java technologies. Whether used as a servlet container or in conjunction with other tools for a more comprehensive application server environment, Tomcat continues to be a vital resource for developers in the Java community.