tomcat

Apache Tomcat is an open-source web server and servlet container maintained by the Apache Software Foundation. It implements the Java Servlet and JavaServer Pages (JSP) specifications, enabling developers to run Java-based web applications packaged as WAR files. Tomcat is widely used as a lightweight alternative to full Java EE servers, providing core web container capabilities without the broader enterprise features.

Technically, Tomcat is organized into components that handle different responsibilities. The servlet container, known as Catalina, manages the lifecycle of servlets, request routing, and session handling. The HTTP connector, named Coyote, accepts and processes client requests, while the JSP engine, Jasper, compiles JSP pages into servlets for execution. Tomcat can operate as a standalone web server or behind an external HTTP server via connectors such as AJP or HTTP proxy configurations. Administration and deployment are performed through configuration files such as server.xml and web.xml, along with deployed web application descriptors.

Tomcat’s feature set includes support for virtual hosts, security realms, and clustering in some configurations. It is designed to be lightweight and extensible, emphasizing compatibility with the Servlet and JSP specifications rather than providing a full Java EE stack (which includes components like EJB and JPA). The project is cross-platform, leveraging the Java Runtime Environment to run on many operating systems, and is distributed under the Apache License 2.0.

History and scope: Tomcat originated as a reference implementation for Java web technologies and became an Apache project in the early 2000s. In recent years, it has undergone changes related to namespace migrations between javax and jakarta, reflecting broader shifts in Java and Jakarta EE.