Apache Tomcat is a popular open-source server for deploying Java-based web applications with efficiency, reliability, and flexibility.
At a glance Apache Tomcat offers; Support for the latest Java Servlet and JavaServer Pages (JSP) specifications, High-performance HTTP and HTTPS connectors, a robust security model, and a comprehensive management and monitoring interface.
Additionally, Apache Tomcat is highly customizable, scalable, and can be run on various operating systems, making it an ideal choice for organizations of any size and industry.
Whether you are a seasoned Java developer or just getting started with web development, this post will provide valuable insights into the many ways in which Tomcat can be used to build powerful and scalable web applications.
Key Highlights
- Apache Tomcat is a Java-based web server and servlet container used to run Java-based web applications.
- It is highly customizable and can be used as a standalone web server or integrated with other web servers like Apache HTTP Server.
- Tomcat is scalable and supports clustering and load balancing for large-scale deployments.
- It requires a compatible Java Runtime Environment (JRE) to run.
- Tomcat provides a deployment descriptor file that configures the application’s behavior on the server.
- Tomcat can be secured by configuring SSL/TLS encryption, implementing access controls, and using secure password policies.
What Is Apache Tomcat?
Apache Tomcat is a web server and servlet container that is used to serve Java-based web applications.
It is open-source software developed by the Apache Software Foundation. Tomcat is written in Java and can run on any operating system that supports Java.
Tomcat provides a platform for deploying Java Servlets and JavaServer Pages (JSPs), which are server-side technologies used for creating dynamic web content.
It also supports other Java technologies such as:
- JavaServer Faces (JSF)
- Java Message Service (JMS)
- Java Persistence API (JPA).
Tomcat is known for its:
- Lightweight design
- Easy configuration
- Strong security features
- Large and active community of developers
It is widely used by developers and organizations for hosting Java-based web applications, including popular web frameworks such as Spring and Struts.
How Does It Work?
Here’s how Apache Tomcat works:
1. Installation and Configuration
To use Apache Tomcat, it must be installed and configured on a server. This involves downloading the software, installing it, and configuring it to work with the operating system and other components.
2. Deployment of Web Applications
Once Apache Tomcat is installed and configured, web applications can be deployed to it. A web application is a collection of HTML, CSS, JavaScript, and Java code that is packaged into a single WAR (Web Archive) file.
This file is then deployed to Tomcat, which unpacks it and makes it available for use.
3. Request Processing
When a client sends an HTTP request to Tomcat, it is received by a listener component called the “Connector“. The Connector is responsible for processing the request and forwarding it to the appropriate “Container“.
4. Container Processing
Tomcat uses “Containers†to process requests. There are two types of containers: “Engine†and “Host“. An Engine is responsible for processing requests that are not associated with a particular host, while a Host is responsible for processing requests for a particular virtual host.
5. Servlet Processing
Once the request has been forwarded to the appropriate container, it is processed by the “Servlet“. A servlet is a Java class that receives the request and generates a response.
6. Response Processing
After the servlet has generated the response, it is sent back to Tomcat, which sends it back to the client.
Tomcat manages sessions by assigning a distinct session ID to each user and keeping user-related information stored. It can handle multiple requests concurrently, allowing it to serve many clients simultaneously.
Hosting Java Web Applications
- Tomcat is widely used as a web server and servlet container to host Java-based web applications, including Java Servlets, JavaServer Pages (JSP), and other Java-based web frameworks.
- It provides a powerful and flexible environment for deploying and running web applications, making it a popular choice among Java developers.
- To run a Java web application, developers typically create a WAR (Web Application Archive) file that contains all the necessary files, including:
- HTML pages
- Images
- Java classes
- configuration files and other resources.
- The WAR file is then deployed to Tomcat, which unpacks the contents of the file and sets up the web application.
- In addition to hosting web applications, Tomcat can also be used to serve static content, such as HTML, CSS, and JavaScript files, although it is not optimized for this purpose.
Servlet Container
- Tomcat is a powerful and flexible servlet container that provides a robust platform for building and deploying Java web applications.
- It manages the lifecycle of servlets, including loading, initialization, and execution. It also handles threading and concurrency issues associated with handling multiple requests from clients.
- Tomcat handles HTTP requests from clients and routes them to the appropriate servlet for processing. It can also handle HTTP sessions, cookies, and other aspects of the HTTP protocol.
- It provides various security features, such as authentication, authorization, and SSL/TLS encryption.
- It can also integrate with external security providers, such as LDAP or Active Directory, to authenticate users and authorize access to web resources.
Scalability And Load Balancing
Scalability/Clustering refers to the ability of an application to handle an increasing amount of traffic while maintaining optimal performance.
Load balancing, on the other hand, refers to the process of distributing incoming traffic across multiple servers to prevent any single server from becoming overwhelmed.
Tomcat provides clustering and load balancing capabilities that allow web applications to be scaled horizontally across multiple servers to handle large volumes of traffic.
- With Tomcat’s clustering feature, multiple Tomcat instances can be connected together to form a cluster, enabling web applications to be spread across multiple servers for improved scalability and fault tolerance.
- Tomcat’s load balancing feature helps to distribute incoming traffic across the servers in the cluster to ensure that no single server becomes overwhelmed with requests.
- By using Tomcat’s clustering and load balancing features, organizations can improve the reliability and performance of their web applications, especially during periods of high traffic. This can help to prevent downtime and ensure that users can access the application without interruption.
Integration With Other Technologies
Apache Tomcat enables web applications to store, retrieve, and manipulate data by integrating with databases.
This integration can be achieved through:
- Java Database Connectivity (JDBC)
- Connection pooling
- Java Persistence API (JPA)
- Hibernate
Systems that can be integrated with Apache Tomcat include:
- Databases – such as MySQL, Oracle, and PostgreSQL, to provide access to data stored in the database. This integration enables web applications to query and retrieve data from the database, and also store data in the database.
- Messaging systems – such as JMS, WebSocket, and SSE, enabling web applications to send and receive messages asynchronously.
- Content management systems (CMS) – such as Joomla, Drupal, and WordPress, providing a reliable server to handle high traffic and store large amounts of data.
- Identity and access management (IAM) systems – for secure access to web applications. This is done through security protocols like OAuth, OIDC, and SAML.
- Business process management (BPM) systems – such as Apache ODE and Activiti, to provide workflow management capabilities for web applications.
Customization And Extensibility
Apache Tomcat is highly customizable, allowing developers to configure various settings to meet the specific needs of a web application.
These settings include:
Thread pools – Configuring the number of threads available to the web application can improve performance and reduce response times, especially when handling multiple requests.
Connection timeouts – Tomcat also allows developers to set the maximum time a connection can remain idle before being terminated.
Cache sizes – Tomcat provides options to configure cache sizes for different components, such as session data and static content, which can significantly improve performance by reducing response times and improving the user experience.
- Tomcat can also be extended with additional components, such as database connectors or authentication modules. These components can be added to Tomcat by installing a plugin or module that provides the necessary functionality.
- Tomcat’s extensibility feature makes it possible to integrate with other systems and tools, such as monitoring tools or content management systems.
Benefits Of Using Tomcat
Open Source
- Apache Tomcat is a popular open-source web server and servlet container that is used to deploy and run Java web applications.
- As an open-source software, Apache Tomcat is free to use, which means that businesses and individuals do not have to pay licensing fees to use it.
- It can be easily modified to meet specific needs or requirements. This allows developers to customize Apache Tomcat according to their specific needs and extend its functionality using open-source modules and plugins.
- It also provides transparency into the codebase, which means that users can inspect the code to ensure that it is secure and does not contain any hidden features or vulnerabilities.
- Apache Tomcat is always evolving to meet user needs and, as an open-source software, promotes innovation by allowing developers to build on the work of others and share their applications.
Platform Independence
- Tomcat is designed to be platform-independent, meaning it can run on different operating systems such as Windows, Linux, macOS, and Unix.
- This feature allows developers to develop applications on their preferred operating system and deploy them on any other operating system supported by Tomcat, without making any significant changes to the application code.
- Developers can write code once and run it on multiple platforms, reducing the effort required to port applications across platforms. This not only saves time and effort but also reduces development costs.
- Moreover, Apache Tomcat’s platform independence feature also allows developers to use a diverse range of tools and technologies to build and deploy their web applications.
- This ensures that developers have the flexibility to choose the tools and technologies that they are comfortable with, rather than being restricted to specific tools and technologies that are only compatible with a specific operating system.
Lightweight And Efficient
- Apache Tomcat is a lightweight web server, which means it has a relatively small footprint in terms of system resources required to run it.
- This makes it ideal for use in environments where system resources are limited, such as embedded systems or cloud-based servers.
- The small size of Tomcat also makes it easier to deploy and manage, as it does not require a lot of disk space or memory to run.
- This can help to reduce the overall cost of deploying and maintaining web applications, especially for small or medium-sized businesses.
- Apache Tomcat is also highly efficient. It is optimized to handle a large number of simultaneous connections and requests, making it ideal for high-traffic web applications.
- It achieves this efficiency by using techniques such as connection pooling and thread reuse to minimize the overhead associated with handling each request.
Support For Java Frameworks
- Apache Tomcat is widely used for hosting web applications built using various Java frameworks.
- With Tomcat’s support for Java frameworks such as Spring and Struts, developers can easily build web applications with advanced features such as dependency injection, MVC (Model-View-Controller) architecture, and more.
- This feature allows developers to easily manage application components and their dependencies, enabling them to build modular, scalable applications.
- In addition, it enables developers to easily separate presentation logic from application logic, improving the overall structure of the application and making it easier to modify or extend in the future.
Large Community And Support
- Apache Tomcat has a large community of developers, contributors, and users who are actively involved in its development, maintenance, and support.
- This community comprises people from different backgrounds, expertise, and geographic locations who come together to collaborate, share knowledge, and contribute to the improvement of the software.
- The community support for Apache Tomcat includes various resources such as: user forums and mailing lists, documentation and code examples.
- User forums and mailing lists enable users to get help from other users and experts in the community.
- The documentation provides user guides, tutorials, and technical documentation for information on installation, configuration, and usage.
- Code examples are also available to help users learn different features of Apache Tomcat.
Conclusion
Tomcat is a powerful and versatile tool that can be used for a variety of purposes, from web application hosting to load balancing and high availability.
Its lightweight design makes it a popular choice for developers who need a simple solution for testing and development, and its open-source nature means that it is continually being improved and updated by a dedicated community of developers.
Whether you’re a developer, a system administrator, or a business owner, Tomcat is a tool that is worth considering for your web hosting and application deployment needs.
Next Steps: What now?
- Choose the best web hosting provider that supports Tomcat
- How to Install and Configure Apache Tomcat on an Ubuntu 18.04 VPS or Dedicated Server
- Find the Best Web Hosting for 2023
