Transaction flows

This section shows some procedural and transaction flow diagrams to help understand a typical sequence of callbacks during a transaction.

Connection

Client		Terminal
ConnectNetwork	->
	<-	ConnectNetwork: returns OK
	<-	callback: LinkStatus(True)
Login	->
	<-	callback: BusyStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: BusyStatus(False)
	<-	Login: returns OK
	<-	callback: Display("Welcome")
Transactions happen, etc...
Disconnect	->
	<-	callback: LinkStatus(False)

Simple transaction

Client		Terminal
Purchase	->
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")
	<-	callback: Display("MasterCard / Ask for PIN / Signature possible")
	<-	callback: Display("Please wait")
	<-	callback: Display("Please wait")
	<-	callback: PrintReceipt, version=Merchant
	<-	callback: PrintReceipt, version=Cardholder
	<-	callback: Display("PURCHASE / Approved / Ask customer to take card")
	<-	callback: CardStatus(False)
	<-	callback: Display("Approved")
	<-	Purchase returns OK
	<-	callback: Display("Welcome")

Pre-amount transaction

This sequence shows a pre-amount transaction, where the transaction is started with no amounts specified, and the amounts are sent later.

Client		Terminal
PurchaseBeforeAmount	->
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")
	<-	callback: Display("MasterCard / Ask for PIN / Signature possible")
	<-	callback: Display("Please wait")
	<-	callback: Display("Chip is read / Waiting for amount")
SendPurchaseAmounts	->
	<-	SendPurchaseAmounts response OK
	<-	callback: Display("Confirm total amount / MasterCard / 550,00 SEK")
	<-	callback: Display("Please wait")
	<-	callback: PrintReceipt, version=Merchant
	<-	callback: Display("Purchase approved / Ask customer to take card")
	<-	callback: CardStatus(False)
	<-	callback: Display("Purchase approved")
	<-	PurchaseBeforeAmount returns OK
	<-	callback: Display("Welcome")

In this example the amounts are sent after the “Waiting for amount” display prompt, but that is not a requirement. Here is a sequence that shows the amount being sent before the card is inserted. Note that there is no “confirm total amount” display, because the amount is shown on the PIN entry screen so the customer has the option to cancel the transaction if the amount is wrong.

Client		Terminal
PurchaseBeforeAmount	->
	<-	callback: Display("New customer / Waiting for card")
SendPurchaseAmounts	->
	<-	SendPurchaseAmounts response OK
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")
	<-	callback: Display("MasterCard / Ask for PIN / Signature possible")
	<-	callback: Display("Please wait")
	<-	callback: PrintReceipt, version=Merchant
	<-	callback: Display("Purchase approved / Ask customer to take card")
	<-	callback: CardStatus(False)
	<-	callback: Display("Purchase approved")
	<-	PurchaseBeforeAmount returns OK
	<-	callback: Display("Welcome")

Purchase with signature verification

The sequence below shows the terminal asking for signature verification during a purchase, where the cardholder has chosen signature rather than PIN.

Note that the merchant receipt is printed earlier than in a non-signature transaction, because the merchant receipt is the one that is signed by the customer.

Note also that the card is removed before signature verification in this sequence.

Client		Terminal
Purchase	->
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")
	<-	callback: Display("MasterCard / Ask for PIN / Signature possible")
	<-	callback: Display("Please wait")
	<-	callback: PrintReceipt, version=Merchant
	<-	callback: Display("550,00 SEK / MasterCard / Ask customer to take card / Verify signature")
	<-	callback: CardStatus(False)
	<-	callback: VerifySignature
VerifySignature returns True, signatureOk=True	->
	<-	callback: PrintReceipt, version=Cardholder
	<-	callback: Display("Purchase approved")
	<-	Purchase returns OK
	<-	callback: Display("Welcome")

Cancelled transaction

A cancelled transaction is where the cardholder chooses to end the transaction early. In this sequence the card is removed at the PIN entry stage. Note the CardStatus callback showing the card removal. Note also that only one receipt is printed here because there is normally no merchant receipt for cancelled transactions.

Client		Terminal
Purchase	->
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")
	<-	callback: Display("MasterCard / Ask for PIN / Signature possible")
	<-	callback: CardStatus(False)
	<-	callback: Display("Transaction aborted")
	<-	callback: PrintReceipt, version=Cardholder
	<-	Purchase returns OK
	<-	callback: Display("Welcome")

Aborted transaction

An aborted transaction is where the transaction is ended early by the client application. As detailed in the API documentation, there is no response to the RequestTransactionAbort method. The client application must wait for the transaction result to be returned and then act accordingly.

Client		Terminal
Purchase	->
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")
	<-	callback: Display("MasterCard / Ask for PIN / Signature possible")
RequestTransactionAbort	->
	<-	callback: Display("Transaction aborted / Ask customer to take card")
	<-	callback: PrintReceipt, version=Cardholder
	<-	callback: CardStatus(False)
	<-	callback: Display("Transaction aborted")
	<-	Purchase returns OK

Refund transaction

A refund transaction behaves in the same way as a simple purchase transaction. It is simpler from the customer’s perspective because there is no PIN entry. The authorisation and authentication responsibility in a refund is on the merchant rather than the card issuer.

Client		Terminal
Refund	->
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")
	<-	callback: Display("Please wait")
	<-	callback: PrintReceipt, version=Merchant
	<-	callback: PrintReceipt, version=Cardholder
	<-	callback: Display("Refund / Approved")
	<-	callback: CardStatus(False)
	<-	callback: Display("Refund / Approved")
	<-	Refund returns OK

Reversal of the last transaction

The last approved transaction can normally be reversed. There is no scope for cardholder interaction here, and the client application will not have to supply any additional information.

Client		Terminal
ReverseLastTransaction	->
	<-	callback: PrintReceipt, version=Merchant
	<-	callback: PrintReceipt, version=Cardholder
	<-	callback: Display("Reversal / Approved")
	<-	Reversal returns OK

Enable the card reader

The client application can enable the card readers (chip card and magnetic stripe readers only) outside of a transaction. This allows the customer to present a card ahead of a transaction being started, allowing the client application more time to establish what kind of transaction is needed.

This can also be used to read bonus / loyalty card information for administrative purposes.

Client		Terminal
EnableCardReaders with enable = True	->
	<-	EnableCardReaders returns OK
	<-	callback: Display("New customer / Waiting for card")
	<-	callback: CardStatus(True)
	<-	callback: Display("Please wait")
	<-	callback: CardAccepted("541333******0020")