I was having so many problems for uploading file on server without post backs. So, need of using IFrame. But, when I use IFrame, while uploading I need to know context and pass some parameters to it. Because when I upload, according to my requirements I need to create a folder on server by using those parameters. So, how to pass data to iFrame and use it for server-side processing. Finally, got it implemented and working perfect. Great solution for it. Look for more in this post.