Dwolla payment button: Is the redirect after successful checkout prevented until callback/notification occurs?

Question

The reason I'm asking this is b/c the page that gets showed to the user after successful purchase typically differs depending on whether or the purchase was actually made.

So one typically MUST know whether or not the purchase was successful before the redirect occurs.

If Dwolla's callback and/or webhook notification isn't guarenteed to arrive first, does anyone have suggestions for how to code (in PHP) the necessary polling/waiting at the redirect URL to allow for the notification to be processed first?

Answer 1

According to Dwolla:

"we never wait for webhooks"

"we do, however, wait for the CALLBACK (I assume they mean the one called "Payment Callback") before we redirect the user back to your site".