Creating Extensible Applications With the Java Platform

Overview

An extensible application is one that the user can extend easily without modifying its original code base. One can enhance its functionality with new plug-ins or modules. Developers, software vendors, and even customers can add new functionality or Application Programming Interfaces (APIs) by simply adding a new Java Archive (JAR) file onto the application classpath or into an application-specific extension directory. This paper describes two ways to create applications with extensible services, which allows the user or others to provide service implementations that require no modifications to the original application. By designing an extensible application, one provides an easy way to upgrade or enhance specific parts of a product without changing the core application.