Automatically set the status to Complete

What file should i look into or modify in order to automatically set the order status to Complete, (notify customer also if possible) whenever a payment gateway callback returned a successful status?

You would do it somewhere in the callback() function of the payment extension for the gateway.

Thanks,
One more thing, i believe in a payment gateway account, its not possible to declare more than 1 postback URL, correct me if im wrong. I currently dont have access to our gateway account for me to check.

How do i make our existing postback URL (which was used on a different shopping cart software) to be able to execute the above mentioned process in Opencart after a purchase on Opencart was made?

I doubt that you could have multiple postbacks. It does not make sense.

If you have to post the callback url to the gateway then the code looks something like the following extract from the existing opencart paypal payment extension if the gateway has a callback setting for your customers, it needs to be something like the result of the above code, which is

Opencart          <--------------------+
                                                    |
                                                    |
                                  script-to-process-callback.php  <-----    Payment  Gateway
                                                    |
                                                    | 
Non-Opencart shop  <----------------+                 

Thanks!, With the workflow shown above, I will call this script http://localhost/store/index.php?contro ... aypal&nbsp; from script-to-process-callback.php. Correct?             

Will try what you suggested

Regards!

paypal was the example payment gateway. You will need to replace that value with the name of your opencart payment extension

yes i noticed that.. Thanks thanks..