Integration with payment gateway

Question

if transaction fails on paypal page or ccavenue page then how can i rollback all processing in php

Answer 1

If you enable IPN posts in the PayPal settings you will get a notification with transaction status. If it fails you can rollback your changes.

Have a look here - https://www.paypal.com/cgi-bin/webscr?cmd=p/xcl/rec/ipn-techview-outside

Answer 2

I think most gateways will make a callback if the payment went through. I usually assume that the payment isnt made until I get the callback. This means that the order is not verified until the callback.