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Questions about IPN

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#1 Guest(old)


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Posted 27 November 2002 - 04:22 AM


The site I'm developing holds all Customer data (name, address, order information) and I want to use PayPal simply to accept payment for the actual purchase.

I have implemented this as Single Item Purchase and I'm prepopulating the payment page. Everything is working well.

When the Customer pays and returns to my site via the return_url I'm inserting the order into the database and giving the order number to the Customer.

The question I have is - what benefit does IPN give me? If the Customer arrives back at the return url, it is safe to assume that a) they have made payment and B) it has been authorised or cleared?

This being the case I'm puzzled as to what benefot IPN would bring in this case.

Or is it the case that the Customer might change the payment amount while on the PayPal site, or their card might be declined - in which case I should thak the Customer, give them their order number, but also implement IPN and wait for this to return an amount and status to me before shipping? (and, if declined, I'd be able to auto generate my own email).

Additionally - if I go with IPN to do this - would payments not taken through the website but instead paid ad-hoc also be sent as updates over IPN, so I need to cater for the fact that my site might receive an IPN for a payment it didn't instigate, so I need to log this separately i.e. not against a web order?

Many thanks.
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#2 DaveC


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Posted 27 November 2002 - 03:06 PM

It helps to prevent a transaction result coming from elsewhere...

Imagine the scenario...

I order from your web site, go through paypal, and pay. At the final screen, I can view source and copy the form source code.

I then go back to your site, put 1000s of items in my basket and go through the motions, but don't click any further to go to paypal. Instead, I have the invoice number (and other details) behind the button that I am about to send to paypal.

I feed this into my own form (that I have taken from the previous results page from paypal) and I have a completed transaction in the eyes of your site, without even having to go through paypal.


Web development - http://www.revilloc.com

#3 paypal_pb


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Posted 27 November 2002 - 03:52 PM

Processing an IPN is more reliable because 1) it doesn't depend on the user pressing "Continue" and 2) the PayPal system will continue sending the IPN until your server successfully processes it (for example, if your server is down).

Patrick Breitenbach
PayPal, Inc.
Dev Net: https://www.paypal.com/pdn

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