Apache Tomcat

Apache Tomcat (developed by The Apache Software Foundation) is an open-source Java web application server and servlet container released under the Apache License version 2.0. Tomcat provides an execution environment and web server for hosting Java-based web applications, implementing core Jakarta EE (formerly Java EE) web specifications including Jakarta Servlet, Jakarta Pages (JSP), Jakarta Expression Language (EL), Jakarta WebSocket, Jakarta Annotations, and Jakarta Authentication.

Specification Implementation & Namespace Migration

Tomcat serves as a reference implementation for Java web technologies across distinct major release lines:

• Tomcat 9.0.x: Implements Java EE 8 specifications using the legacy javax.* API package namespace. The Apache Software Foundation announced the official End of Support (EOS) for Tomcat 9.0.x as March 31, 2027.
• Tomcat 10.1.x: Implements Jakarta EE 10 specifications, transitioning API package imports from javax.* to the jakarta.* namespace following the transfer of Java EE stewardship to the Eclipse Foundation.
• Tomcat 11.0.x: Implements Jakarta EE 11 specifications using the jakarta.* namespace.

Because the transition from Java EE to Jakarta EE requires package namespace updates in application source code, Apache provides the open-source Apache Tomcat Migration Tool for Jakarta EE to automate bytecode and source code conversion from javax.* to jakarta.*.

Project Components & Native Connectors

The Apache Tomcat project includes supporting sub-projects and execution utilities:

• Tomcat Native: An optional library that integrates the Apache Portable Runtime (APR) and OpenSSL native libraries to enhance HTTP/2, TLS, and asynchronous I/O performance.
• Tomcat Connectors (JK/AJP): Middleware plugins that enable web servers (such as Apache HTTP Server or IIS) to proxy web requests to Tomcat via the Apache JServ Protocol (AJP).
• Tomcat Maven Plugin: Build integration tools for deploying and managing Web Application Archive (WAR) files within Tomcat servlet containers during automated development pipelines.