Book Image

Apache Geronimo 2.1: Quick Reference

Book Image

Apache Geronimo 2.1: Quick Reference

Overview of this book

Apache Geronimo is a robust, scalable, secure, and high-performing application server. But like all application servers, this power comes with a steep learning curve. This book can help you save your time and get working with Geronimo in matter of a few hours. This book is a quick-reference guide to Apache Geronimo that mitigates the starting pains that most developers have when they migrate to a new Application Server. It will help you to extend and amplify your existing development skills, empowering you to build new types of applications regardless of the platform or browser. The book will introduce you to the exciting features of Apache Geronimo Application Server. You will see how easily you can develop and deploy Java EE 5 applications on Geronimo. It covers everything from downloading the server to customizing it using custom GBeans. By following the practical examples in this book, you will be able to develop applications quickly using Geronimo Eclipse Plugin. The book covers Geronimo internals in detail, which helps you write custom services on Geronimo. Also, it helps you to gain a deep understanding of Geronimo plugin architecture and teaches you to extend your server functionality via plugins. By the end of the book, you will develop proficiency in Geronimo and Java EE 5 application development.
Table of Contents (21 chapters)
Apache Geronimo 2.1
Credits
About the Authors
About the Reviewer
Preface

Class loader architecture


This section covers the class loader architecture for Apache Geronimo. The following image shows the class loader hierarchy for an application that is deployed in Apache Geronimo:

The BootStrap class loader of the JVM is followed by the Extensions class loader and then the System class loader. The j2ee-system class loader is the primary class loader of Apache Geronimo. After the j2ee-system class loader, there are multiple other layers of class loaders before reaching the application class loaders. Applications have an application class loader, which loads any required application-level libraries and EJB modules. However, the web application packaged in the EAR will have its own class loader. The Administration Console has a ClassLoader Viewer portlet that can be used to view the class loader hierarchy as well as the classes loaded by each class loader.

Modifying default class loading behavior

In certain situations, we will need to follow a class loading strategy...