What is Tomcat?

With the numerous online publications about this software, we have come to understand that Apache Tomcat is a software that runs on the Java server. What is Tomcat? This is a question that many top Java devs have asked in the past, even while using this technology. Not many have really understood why this software was needed in the first place.  

Tomcat was developed at Sun Microsystems as the standard reference implementation of Java Servlet and Java Server Pages (JSP), and the source base was eventually contributed to the Apache Software Foundation.

Since then, other Sun volunteers have contributed to the product, leading to its accreditation as a top-level Apache project in 2005. Some businesses have been using Apache Tomcat since it implements Java EE (Java Enterprise Edition) requirements – for enterprise applications like:

  • Java Expression Language
  • Java Servlet
  • Java WebSockets
  • Java Server Pages

Tomcat: an Application or a Web Server?

Apache Tomcat 10.0.x is the latest stable version and the first Tomcat release to support Java Servlet 5.0, JavaServer Pages 3.0, Java Expression Language 4.0, WebSocket 2.0, and Authentication 2.0 specifications. As always, Tomcat has been considered a web server and not an application server due to the Tomcat web server applications functionality and Servlet containers.

Unlike Java EE, Tomcat does not have the entire feature to function as an application server, which is not always a drawback. Many applications require only Tomcat’s functionalities; thus, using heavier tools is unnecessary. If the functionality Apache Tomcat provides is sufficient, you can use the Apache web server for production applications that process up to a million requests. With that, Tomcat is a ready-to-use tool as a web server app.

How does Apache Tomcat work?

Apache Tomcat offers a robust and efficient environment for hosting Java-based web applications, making it a popular choice for Java web application developers and organizations seeking a powerful, open-source web server application and servlet container solution.

Request Handling:

A request is handled when a client (typically a web browser) sends an HTTP server request to the Tomcat server, and the server listens on the specified port that is default 8080. The incoming requests are being treated and handled by Tomcat via its server-designed own HTTP protocol connector, which receives and processes the request data.

Catalina Servlet Container:

Tomcat includes a core component called Catalina, which acts as a Servlet container. It manages the lifecycle of servlets and JSP pages, handles request dispatching, and maintains the flow of data between clients, application servers, and servlets.

Tomcat Connector:

When the Java Servlet or Java Server Pages create a response, Tomcat transmits it back to the client via its HTTP connection. The connector is in charge of converting the answer into a format that the client can understand, such as HTML.

Web Applications:

Tomcat arranges web applications as distinct entities. Each web application comprises resources such as HTML with Java code, Server Pages, Java Servlets, libraries, and other items required to execute the program. These web applications are stored in Tomcat’s “webapps” directory as folders or WAR (Web Application Archive) files.


When Tomcat starts up, it scans the “webapps” directory and deploys each web application it finds. During deployment, Tomcat creates a separate classloader for each application, ensuring isolation of file system and preventing conflicts between different applications.

Java Servlet Processing:

Tomcat forwards the request and response objects to the selected Java Server Pages or Java Servlets application server. The Java Server Pages or Java Servlets then process the request, generate the response, and sends it back to Tomcat.

Additional Resources:

For additional resources like HTML, CSS, and images, Tomcat serves them directly without involving the Java Servlet container. This helps to handle simple resource requests efficiently.

Session Management:

Tomcat manages sessions for users interacting with web applications. It tracks sessions through session identifiers stored in cookies or URL rewriting. Sessions allow the web server and applications to maintain a state across multiple requests from the same client.

Java Servlets and Java Server Pages:

When an HTTP request arrives for a specific URL pattern (configured in the web application’s deployment descriptor), Tomcat determines which Java Server Pages or Java Servlets should handle the request based on the mappings defined. It loads the appropriate servlet or compiles the full Java servlet specification or Server Pages if necessary.

Shutdown and Maintenance:

Tomcat can be gracefully shut down or restarted. During shutdown, it closes all connections, releases local system resources, and stops all running threads.

Pros of Tomcat Server

  1. Tomcat Java Enterprise Edition is compatible and supports Java servlets, Java Server Pages (JSP), Java Expression Language (EL), WebSocket, and other Java EE technologies, allowing software engineers to build robust and scalable web applications.
  2. It creates a straightforward and easy-to-configure atmosphere for software engineers looking to use it. This simplicity makes it easier for developers and system administrators to set up and manage the server.
  3. With its extensible nature, you can practically customize it to your heart’s content. Add extra features, components, and even some flair with some of those custom ideas or third-party modules.
  4. Tomcat was created to be a lightweight, fast, and efficient technology.  It’s designed to be a lightweight speedster, zooming through with its small footprint, and starts up quickly, making it ideal for environments with limited memory or processing power.
  5. Since it’s an open-source technology under the Apache License, so it’s a no-cost deal for everyone. Whether you’re a startup, a mid-sized business, or a big corporation, Tomcat’s web servers are open to all.
  6. Apache Tomcat has a large user and technical community and has been around for a long time. There is a robust and active development community for the Apache Tomcat project. It is a well-known and trustworthy server with a proven dependability and security track record.
  7. Tomcat supports clustering, which enables multiple Tomcat instances to work together, sharing the load and providing high availability for web applications. This feature is crucial for scaling applications and ensuring continuous service.

Cons of Tomcat server

  1. Yes, Tomcat is great, but it has its limitation for Java projects that has to do with more Enterprise Edition – like Enterprise Java Beans or Java Transaction APIs
  2. Configuring Tomcat is easy, and you can use it for simple projects, but when it comes to handling more advanced features like clustering and all those high-level security projects. It is not the best, but just an option to choose from. 
  3. Most time depends on third-party tools to come up with graphical management to help manage your Tomcat instances. 
  4. When it comes to deploying your web apps, Tomcat has a straightforward process. However, some other servers go the extra mile with features like better deployment, making your development life even smoother.

With most users using Tomcat among Java engineers, Tomcat is truly popular among the Java applications devs. It offers the basic functionality needed for Java enterprise application server for small applications and can be redeployed multiple times as needed. It’s also worth noting that Tomcat is not a one-size-fits-all Java application server. The demands provided by the application always determine the proper server.


Tomcat is an open-source server for Java-based applications. It works on any platform and is simple to download and install on your computer. As long as you have a static IP address, you can launch your Java or WordPress website without issues. You can also check out our blog for Jenkins in Tomcat server and get a better understanding of the best cloud server hosting infrastructure for you to install Tomcat for web servers today!