[Event(name="dataByConstraintRequest", type=...)]
 public class SomeDataViewMediator extends EventDispatcher {
    private function onDataRequestFromView(event:Event):void {
       var constraint:Constraint =
             QuerySpecUtil.createConstraintForRelationship(hostRef, "vm");
       var request:DataByConstraintRequest=
             new DataByConstraintRequest.newInstance(
                   constraint,
                   model);
       dispatchEvent(request);
    }
 
    // Option 1 - use EventHandler for the response
    [EventHandler(name="dataByConstraintResponse")]
    private function onDataRetrieved(response:MultiObjectDataResponse):void {
       // response.result contains VmListItemData objects
       _view.vmList.dataProvider = response.result;
    }
 
    // Option 2 - use ResponseHandler for the response
    [ResponseHandler(name="dataByConstraintResponse")]
    public function onDataRetrieved(request:DataByConstraintRequest,
                                     result:ArrayCollection,
                                     error:Error):void {
       // result contains VmListItemData objects
       _view.vmList.dataProvider = result;
    }
 }