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Dynamic Class Loading in the JavaTM Virtual Machine. Execution. Execution. Execution. Inside Class Loaders. By Andreas Schaefer 11/12/2003 This series of articles started when I wanted to write a weblog about the impact of class loaders in a J2EE server. But the log entry grew, due the fact that a few basic rules still can provide a complex system, as you see in physics, where a few basic components and forces can build up something like our universe with all of the stars, black holes, pulsars, galaxies, and planets. In this part, I want to lay the groundwork on which we can start a discussion about dynamic and modular software systems.

Class loaders may seem to be a dry topic, but I think it is one of the topics that separate the junior from the senior software engineer, so bear with me for an exciting journey into the darker corners of Java. Now you may ask yourself, "Why should I deal with multiple class loaders and their limitations and problems? " The short answer is that you probably have to, one way or the other. First we need to explain some definitions: Figure 1. Class Linking Test. Enterprise Java Community: Understanding J2EE Application Server. Introduction The packaging mechanisms defined in Chapter 8 of the J2EE 1.3 specification provide a framework for pulling together all the pieces of a J2EE application. However, application server vendors are free to design a proprietary class loading hierarchy for obtaining the classes and resources found in an application. A class loading hierarchy is typically used to enable features such as hot redeployment and application independence.

By submitting your personal information, you agree that TechTarget and its partners may contact you regarding relevant content, products and special offers. You also agree that your personal information may be transferred and processed in the United States, and that you have read and agree to the Terms of Use and the Privacy Policy. Understanding the class loading architectures of major application server vendors helps J2EE developers design application packaging structures that are both portable and efficient. Class Loading Basics WebSphere 4.0 Conclusion.