Why this book?

Tomcat is one of the few technology areas that is particularly blessed with a plethora of very well written books, and the Tomcat mailing lists are rather friendly places for new developers. So really, why another book on Tomcat?

The answer is simple. Most of these books and material focus primarily on the set up, administration, and management, of a Tomcat server.

This is no accident. Most web developers rarely have to concern themselves with anything more challenging than setting up a context fragment or changing the default port for Tomcat from 8080 to 80.

As long as a developer understands the basic terminology of web applications (such as the context, the context root) and the structure of a WAR file, most modern Integrated Development Environments (IDEs), such as Eclipse and IntelliJ IDEA, do all the heavy lifting for you.

It seems only appropriate then, for authors to target their books at the typical administrator or deployer.

For its part, Tomcat exposes a myriad of configuration files that enable even an obsessive administrator to fine tune the installation and the Java Virtual Machine as much as desired.

The net result is that your average book contains the customary chapter on installing Tomcat, chapters on configuring it, on deploying servlets into it, on integration with either the Apache httpd web server or Microsoft's IIS, and on securing the installation.

The downside with this approach is that it provides a one-sided view of the software engineering marvel that is Tomcat. You tend to see it as a black box with lots of control switches that you can throw, but you never ever really get a chance to peer into the open vents on the sides of that box.

In this book, I hope to correct that imbalance. I'm going to pry open the service door on the side of that black box, and take you in on an interesting journey through some of the sights that most people rarely get to see. A connector shimmering in the moonlight, the rays of the early morning sun catching an application class loader in its native state, a lumbering valve caught in motion capture frames as it springs into action with surprising agility. There are a lot of fantastical beings that populate this world, if you only dare to venture into it.

In the course of the next few chapters, we will look at Tomcat from the perspective of someone attempting to understand what makes it tick. Our goal will be to understand Tomcat as few others do. We'll not only see the control switches on the outside, but we'll also learn about how these switches affect the machinery within.