c# - How to notify to client side of asynchronous method completion in asp.net

Question

I am new to delegates for asynchronous calling. I am using the following code to call a UploadVideo method asynchronously.

UploadVideoDelegate delUploadVideo;        
AsyncCallback objAsyncCallBack = new AsyncCallback(this.TocuhLogResult);        
IAsyncResult objIAsyncRes;        
delUploadVideo = new UploadVideoDelegate(UploadVideo);        
objIAsyncRes = delInsertTouchLogToDB.BeginInvoke(videos[videocount++],           objAsyncCallBack,     null)

But, how can I notify that your upload is completed on client-side. Like showing a message that upload is Completed.