title: How can I upload files asynchronously on ASP.NET?
body: <p>I've been looking for a way to achieve this behavior and I <a href="http://www.codeproject.com/KB/ajax/GmailUpload.aspx" rel="nofollow">found this sample project</a>.</p>
  
  <p>The trick in this project is that it changes the <code>form</code> target to an <code>iframe</code> created on the fly.</p>
  
  <p>So far so good, I can get the <code>byte[]</code> on the server-side. But I need to change an image preview after the file is uploaded.</p>
  
  <p>How can I get the <code>iframe</code> to update the main page? Would I have to save it on a file on the disk, make a javascript callback to change the image url? Is there another way to do this? What's recommended?</p>
  
  <hr>
  
  <p><a href="http://www.asp.net/ajax/ajaxcontroltoolkit/Samples/AsyncFileUpload/AsyncFileUpload.aspx" rel="nofollow">This control</a> suggested by vorrtex actually causes a full page postback, am I missing something or is it the correct behavior?</p>