The Extension Mechanism
for Support of Optional Packages
Optional packages are packages of classes (and any associated native code) that application developers can use to extend the functionality of the core platform. The extension mechanism allows the Java virtual machine (VM) to use the classes of the optional extension in much the same way as the VM uses classes in the Java Platform. The extension mechanism also provides a way for needed optional packages to be retrieved from specified URLs when they are not already installed in the JDK or JRE.
The following classes play a role in the extension mechanism:
Tutorials and Programmer's Guides
Located on the Java Software website: