The HierarchicalDataSourceControl.OnDataSourceChanged(EventArgs) method notifies a data-bound control that the underlying data source or the data cached in memory has changed, that the control should rebind, and that any necessary work should be performed.

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

The HierarchicalDataSourceControl.OnDataSourceChanged(EventArgs) method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.