IPN Class

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The IPN component is used to validate an Instant Payment Notification, to make sure it is not fraudulent and was actually sent by PayPal.

Syntax

IPN

Remarks

The IPN class can be used by the merchant to verify that a received Instant Payment Notification did indeed come from PayPal. PayPal will post the Instant Payment Notification to the merchant's web site indicated in their PayPal Profile.

When an Instant Payment Notification is received, simply pass the posted data to the FillFormVars method to automatically parse it and store it into the FormVars collection. Then call the VerifyIPN method. The Response property will then indicate whether the IPN was sent by PayPal ("VERIFIED") or was fraudulent ("INVALID").

After the Instant Payment Notification has been verified, it is parsed into properties which contain vital transaction details, such as the Payer's email, shipping address, the item sold, payment amount, etc, to further process the transaction (i.e. Ship the item, automatically send a login/password, or update a database).

The following code shows how to verify an Instant Payment Notification received from PayPal:

class.FillFormVars(Request.Form())
class.VerifyIPN()
If (class.Response = "VERIFIED") Then
  ProcessOrder() ' Process the order
Else
  LogError() ' Log the error and ignore this fraudulent IPN.
End If

If the programming language you are using does not allow you to request the entire form as shown above, you must manually parse the IPN, as shown below:

Enumeration en = request.getParameterNames();
while (en.hasMoreElements()){
  String paramName = (String) en.nextElement();
  String paramValue = request.getParameter(paramName);
  class.addFormVar(paramName, paramValue);
}
class.verifyIPN();
if (class.getResponse().equals("VERIFIED")) {
  processOrder(); // Process the order
} else {
  logError(); // Log the error and ignore this fraudulent IPN.
}