Everything is plug-ins running on or loaded by plug-ins loader called by a small kernal
which is an implementation of the OSGi R4 specification and provides the environment in which plug-ins execute.
Contribution Principle: Every extension is a contribution which services to another extension.
• EAF - http://www.eclipse.org/home/categories/frameworks.php
• OSGi - http://www.eclipse.org/equinox/
• RCP - http://www.eclipse.org/home/categories/rcp.php