From Joomla! Documentation
The "API15" namespace is an archived namespace. This page contains information for a Joomla! version which is no longer supported. It exists only as a historical reference, it will not be improved and its content may be incomplete and/or contain broken links.
JObserver is an abstract class which provides basic functionality to use the Observer/Observable design pattern within a Joomla Application. See also JObservable.
|update||Method to update the state of observable objects|
jimport( 'joomla.base.observer' );