What Is Apache Tomcat?
What Tomcat Is
Apache Tomcat is an open-source server that runs Java web applications. It is a servlet container: it implements the Jakarta Servlet and JavaServer Pages (JSP) specifications and manages the lifecycle of the Java programs that handle web requests. Tomcat itself is written in Java and runs on the Java Virtual Machine (JVM).
Tomcat can also serve static files and accept HTTP requests directly. It is often placed behind another web server, such as Apache HTTP Server or Nginx, which handles encryption and static content while Tomcat runs the application logic. It is not a full Jakarta EE application server, which adds further enterprise services.
Key Terms: JVM, Servlets, JSP and WAR Files
- JVM: the Java Virtual Machine executes compiled Java bytecode. A Java application needs a compatible JVM on the server, which is its runtime environment.
- Servlet: a Java class that receives an HTTP request and produces a response. Tomcat creates, reuses and destroys servlets according to the specification.
- JSP: a template format that mixes HTML with Java code. The container translates each JSP page into a servlet the first time it is requested.
- WAR file: a web application archive that packages compiled classes, libraries, pages and configuration into one file, which Tomcat deploys.
Why Java Hosting Differs From PHP Hosting
A PHP script is usually read and run by the PHP handler each time a request arrives. A Java web application works differently: Tomcat runs as a long-lived process, the JVM keeps compiled code in memory, and its memory size is set in advance. Hosting for Java therefore needs a suitable JVM version, enough memory for the process and a way to restart the service when it stops.
Deployment also differs. Java applications are usually built into a WAR file on a development machine and then deployed to Tomcat, rather than uploading source files to the server. This separates code from the running environment and makes releases easier to repeat.
Frequently asked questions
Is Apache Tomcat the Same as Java?
No. Java is a programming language, and the JVM is the runtime that executes its compiled code. Tomcat is a server application written in Java that hosts Java web applications. A Java program can run without Tomcat, but a Java web application that handles HTTP requests through servlets needs a servlet container such as Tomcat.
Can Tomcat Run PHP or Python Applications?
No. Tomcat runs Java-based applications, such as servlets, JSP pages and other JVM languages that target the servlet API. PHP and Python applications need their own runtimes and handlers, which is why they are hosted differently.
Does Tomcat Need Apache HTTP Server?
No. Tomcat can accept HTTP requests on its own. Many production setups still place it behind Apache HTTP Server or Nginx to handle HTTPS, static files and other web server duties. Apache HTTP Server and Apache Tomcat are separate products from the same foundation, and each does a different job.