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paypalpaypal-ipnpaypal-sandbox

How can multiple URLS in a row be called by PayPal IPN mechanism?

My understanding of the Paypal IPN mechanism is that my website should send over a message that includes:

  1. a URL to go to if the USER completes the Paypal payment process

  2. a URL to go to if the user hits CANCEL instead

  3. a URL to go to once the payment has been checked for validity (after the user completes it).

But this doesn't makes sense.

I have an asp.net site.

I give the user a payment page. He enters how many widgets he wants to pay for. Then it routes him to PayPal.

Lets say he completes all the steps to pay me. So now he is sent to my website again, at the URL in #1, which tells him that the payment should be verified within 5 minutes. But then, a few milliseconds later, according to my (probably wrong) understanding, he should be sent to the URL in #3. This URL is a blank page, since all it does is execute code that stores the successful invoice in a database.

When I actually try it, he is sent to URL #1, but there is no indication that he is sent to URL #3. No invoice is stored, no blank page appears either.

I am using the sandbox, not the real site. Also, all my pages are protected by a password, but that doesn't block URL #1 (since the user is logged in), so my guess is it should not block URL #3.

Any help is appreciated.

Solution

  • My understanding of the Paypal IPN mechanism is that my website should send over a message that includes:

    a URL to go to if the USER completes the Paypal payment process

    Correct.

    a URL to go to if the user hits CANCEL instead

    Correct.

    a URL to go to once the payment has been checked for validity (after the user completes it).

    Incorrect. That's a URL for PayPal to POST to, independently of the current browser session, when the payment is completed. That is your IPN handler.

    But this doesn't makes sense.

    Agreed. It isn't correct either.

    When I actually try it, he is sent to URL #1, but there is no indication that he is sent to URL #3. No invoice is stored, no blank page appears either.

    He isn't. PayPal tries to POST an IPN to that URL. You're supposed to have something listening there to process the transaction. There are further requirements of that IPN handler such as validation, duplicate handling, etc, which you need to familiarize yourself with.