Occurs when the data storage that the System.Web.UI.IHierarchicalDataSource interface represents has changed.
The IHierarchicalDataSource.DataSourceChanged event is raised when a change is made to the data source control's properties, such as changing the System.Web.UI.WebControls.XmlDataSource.DataFile property of an System.Web.UI.WebControls.XmlDataSource control, or changing the data in the underlying data storage, which happens when XML nodes are changed by an edit action performed by an System.Web.UI.WebControls.XmlDataSource control.