Book Image

Tomcat 6 Developer's Guide

Book Image

Tomcat 6 Developer's Guide

Overview of this book

While Tomcat is one of the most popular servlet containers, its inner workings still remain a mystery to many developers. If you only have a superficial familiarity of how this container actually functions, much of its power remains untapped and underutilized. This book will provide you with all that you need to undertand how to effectively use Apache Tomcat. This book begins by providing detailed instructions on building a Tomcat distribution. The next few chapters introduce you to the conceptual underpinnings of web servers, the Java EE and servlet specifications, and the Tomcat container. Subsequent chapters address the key Tomcat components, taking care to provide you with the information needed to understand the internal workings of each component. Detailed examples let you walk through a Tomcat installation, stepping into key Tomcat components, as well as into your own custom servlets. During the course of the book you will encounter various structural components such as the Server and Service; containers such as the Engine, Host, Context, and Wrapper; and helpers such as the Loader, Manager, and Valve. You will also see how Tomcat implements the JNDI API to provide both a directory service for storage agnostic access to its resources, as well as a naming service that implements the Java EE Environment Naming Context. Along the way you will learn how various elements of the servlet 2.5 specification, as well as the HTTP RFCs are implemented by a servlet container. By the end of your journey, you will be able to count yourself as part of the elite minority of Java EE web developers who truly understand what goes on under the covers of a servlet container.
Table of Contents (17 chapters)
Tomcat 6 Developer's Guide
Credits
About the author
Acknowledgement
About the reviewers
Preface

Containers


This figure provides a closer look at the compositional hierarchy of the container components, their nested components, and their request processing pipelines and valves.

The outermost container represents the Catalina servlet engine and is the subject of this chapter.

Note

An engine cannot be contained by any component other than its service. Adding an engine as a child of any other container will cause an IllegalArgumentException to be thrown.

Note that while the Service component does contain other components, it is not considered a container, and is instead classified as a Top Level Component.

An Engine contains one or more children that are of type Host, each of which is a virtual host. In turn, a Host contains a number of Contexts, each of which represents a single web application. A context may optionally contain Wrapper components, where each wrapper represents an individual servlet.

Some child containers, such as the Host, Context, and Wrapper can have more than one instance...