Supporting plugins in your component/4/en

From Joomla! Documentation

Joomla! Observer Implementation[edit]

Joomla! implements the Observer pattern at a global level through the JPlugin (Observer) and JEventDispatcher (Observable) classes. Anyone wanting to receive notification of events will create a plug-in that extends the JPlugin class. Subclasses of JPlugin will automatically register themselves to the global JEventDispatcher class when their plug-in category has been loaded (more on that later). The JEventDispatcher class is used as a dispatching mechanism that receives events from the communicators and forwards them on to the listeners that have been loaded. For a full explanation of this it is recommended to read the Plugin Developer Overview