request_response_for_assets.as

// in the context

injector.map(AssetRequestSignal).asSingleton();

// in the model/service

[Inject]
public var assetRequestSignal:AssetRequestSignal;

function setUp():void
{
  assetRequestSignal.add( handleRequest );
}

function handleRequest(assetID:String, responseSignal:OnceSignal):void
{
	if(_cachedAssetsByID[assetID]) 
		responseSignal.dispatch(_cachedAssetsByID[assetID]);
	else
		loadAsset(assetID, responseSignal);
}

function loadAsset(assetID:String, responseSignal:OnceSignal):void
{
	// load the assets and then respond when loaded
}

// in the view:

[Inject]
public var assetRequestSignal:AssetRequestSignal;

private var assetResponseSignal:OnceSignal;

function init():void
{
	assetResponseSignal = new OnceSignal(DisplayObject);
	assetResponseSignal.addOnce( handleAssets );
	assetRequestSignal.dispatch( someSortOfAssetID, assetResponseSignal );
}

function handleAssets(asset:DisplayObject):void
{
	if(!asset)
		// oh shit...
	else
		// do stuff as required
}