Calling a handler in JS to get upload file progress

I have a form with an embeded iframe which points to a upload.aspx. During the upload that happens within the iframe, I'm trying to get the progress of the upload by implement开发者_C百科ing my own HttpHandler, however, the request is blocked until the upload completes.

Is there a request limit that I can change in the web.config? Is this even the problem?

Thanks

You probably need to implement HttpModule. Read here: HttpHandler or HttpModule for file upload, large files, progress indicator?