Eclipse platform is built on OSGi framework.
Eclipse Plugin framework is pretty complex. However, the general ideas behind is very simple. In this post, the simple idea of how a plugin works is explained by using a diagram. Then a simple Eclipse Plugin is created to explain how to add a menu item to menu bar.
In the Eclipse model, each plug-in works above Eclipse Platform. Each plug-in may be related to another plug-in by one of two relationships:
1. Dependency. In the diagram above, Plugin A is dependent on Plugin B.
2. Extension. In the diagram above, Plugin A extends Plugin C.