3.7 Step 6: Transaction Notifications to Merchant

3.7.4. Asynchronous Call-back

Figure 9. Asynchronous Call–Back XML Encoded Data
Figure 10. Asynchronous Call–Back JSON Encoded Data
Table 12. Asynchronous Call–back POST Fields
Field Name
(Case–Sensitive)
Required
Mandatory
Optional
Type
(max length)
Description
Stamp M String Unique identifier issued by the merchant representing the instance of the request (preferably a GUID).
This will be the value passed in RequestIdentifier field.
Session M String The transaction session ID, initialised on receipt of the payment request.
Status M String Indicates the current status of transaction. Valid values:
  • Initialised (sent on first call-back)
  • Success
  • Failure
TransactionID M String Unique transaction identifier provided returned by VPG
Identifier M String Value that uniquely identifies an order submitted for processing. (Merchant Reference)
ControlKey M String Encrypted value used to check that the values posted back correspond to a valid Payment Gateway post–back for the TransactionStatusCallbackURL.
It is constructed using a Hash of the Stamp/Session/Identifier encrypted with the merchant's encryption key).
See Appendix C for details on how this value is generated.
Amount M Decimal The amount of the transaction
AuthCode M String The authorisation code returned by the bank
MaskedCardNumber M String The PAN (Card Number) of the customer's card used to make the payment masked with asterisk's to show only the last four–digits.
PaymentType M String The payment option that was selected by the user. Valid values:
  • VisaMasterCard
  • Masterpass
  • Vodaypay
RetrievalReferenceNumber M String The reference that is used to track the transaction with the acquiring bank.

The API response format is dependent on value specified in TransactionStatusCallbackFormat field.
The response message will be sent as an http URL encoded form.
The encoded message will be either XML or JSON.

Figure 11. XML Post–Back Example
Figure 12. JSON Post–Back Example

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