The list of default fields or actions may be based on properties of the adapter or properties of other components. For example, the default fields of TDataSetAdapter are based on the fields in the dataset. If the TDataSetAdapter references a different dataset then the default fields list will change. If the dataset's field list changes then TDataSetAdapter's default fields will change. DefaultWebCompoentsChange is called in these circumstances so that components that are using this adapter can be notified of changes to the list of fields or actions. DefaultWebComponentsChange calls NotifyAdapterChange. 

NotifyAdapterChange