Amazon S3 POST, event when done?

Question

I'm using Amazon S3 with a simple project, when the user uploads a file, I first use an XMLHTTPRequest to send the details to my database, then trigger the form POST that uploads the file straight to S3.

What I can't quite work out though is how to tell when the upload is done so I can update the display properly (I'm cheating at the moment and just updating the display once it's saved in the database, you can barely tell for small uploads, but obviously a problem in the long run.)

The S3 server appears to "cancel navigation" once the upload is complete, so the page doesn't reload - are there any events that are fired that I can use to detect when the upload is complete?

EDIT: I'm using the form code from here http://s3.amazonaws.com/doc/s3-example-code/post/post_sample.html just added an onsubmit to the form that fires the XMLHTTPRequest to my own server before the form gets posted to amazon.

Answer 1

Amazon S3 will redirect to the url specified in the success_action_redirect field or if that's not specified, it returns an empty document with the status code specified in success_action_status.

On completion of the POST, the user is redirected to the location that you specified in the success_action_redirect field. If Amazon S3 cannot interpret the URL, it ignores the success_action_redirect field.

If success_action_redirect is not specified, Amazon S3 returns the empty document type specified in the success_action_status field.

If the POST fails, Amazon S3 displays an error and does not provide a redirect.

See the AWS docs for more details.

Answer 2

Amazon S3 won't trigger any kind of event, but your XMLHTTPRequest code should be able to trigger a callback when S3 returns an HTTP 200 status code.

If S3 isn't returning a successful response code, it's quite possible that S3 doesn't know that your upload is complete. Are you sending a Content-Length header as part of your request?