What is Apache Tomcat?

Apache Tomcat is an open-source implementation of the Java Servlet, JavaServer Pages (JSP), and Java Expression Language technologies. It serves as a web application container or application server for Java-based web applications. Tomcat is developed and maintained by the Apache Software Foundation.

Key features and components of Apache Tomcat include:

1. Servlet Container:

   • Tomcat functions as a servlet container, providing support for the Java Servlet API. Servlets are Java-based components that extend the functionality of a web server to handle dynamic content generation and processing.

2. JSP Support:

   • Tomcat supports JavaServer Pages (JSP), which is a technology that allows developers to embed Java code within HTML pages. JSP pages are compiled into servlets by the container during runtime.

3. Java Expression Language (EL):

   • Tomcat supports Java Expression Language, which is a scripting language used in JSP pages for embedding expressions and variables. It simplifies the access to Java objects and methods within JSP pages.

4. JavaServer Faces (JSF) Support:

   • Tomcat supports JavaServer Faces, a Java web application framework for building component-based user interfaces for web applications.

5. Web Connector:

   • Tomcat includes connectors to integrate with web servers like Apache HTTP Server or Microsoft Internet Information Services (IIS). These connectors allow Tomcat to handle dynamic content processing while the web server handles static content.

6. Catalina:

   • Catalina is the servlet container within Tomcat. It manages the execution of servlets, JSP pages, and other components.

7. Embedded Tomcat:

   • Tomcat can be embedded in other Java applications, allowing developers to include servlet and JSP capabilities in their applications without deploying a separate server.

8. Clustering and Load Balancing:

   • Tomcat supports clustering and load balancing, enabling the deployment of scalable and high-availability web applications.

9. Security Features:

   • Tomcat provides various security features, including authentication, authorization, and secure socket layer (SSL) support.

10. Management and Monitoring:

    • Tomcat includes tools and interfaces for managing and monitoring the server. The Tomcat Manager web application allows administrators to deploy, undeploy, and manage web applications.

Apache Tomcat is widely used for deploying Java-based web applications due to its lightweight nature, simplicity, and open-source licensing. It is suitable for both small-scale applications and larger, more complex deployments. Many organizations use Tomcat as the underlying web server for their Java web applications in production environments.