Android Open Payment Initiative library

This Kotlin library for connecting EFT terminals based on OPI (Open Payments Initiative. This is a communication protocol between the EPOS application and any solution for cashless payments solution installed on the EFT/PoS terminal.)

Usage

Create terminal instance:

      private val externalTerminal = Terminal.Builder()
        .inputPort(inputPort)
        .outputPort(outputPort)
        .ipAddress(ipAddress)
        .applicationSender("yourAppName")
        .workstationID(deviceName)
        .timeout(40000)
        .logger(opiLogger)
        .build()

Login:

    fun login(): ServiceResponse {
    val serviceRequest = ServiceRequest(
            requestType = RequestType.Login.name,
            workstationID = workstationID,
            requestID = "0",
            applicationSender = applicationSender,
            posData = ServiceRequest.PosData(posTimeStamp = Date())
    )
    return callWithShutdown(serviceRequest)
}

Make transaction::

   fun transaction(paymentData: Payment): CardResponse {
       val cardServiceRequest = CardRequest(
            requestID = paymentData.transactionId,
            workstationID = workstationID,
            requestType = RequestType.CardPayment.name,
            posData = CardRequest.PosData(
                    posTimeStamp = Date().toServerUTCFormat(),
                    usePreselectedCard = false
            ),
            privateData = CardRequest.PrivateData(
                    lastReceiptNumber = paymentData.lastReceiptNumber.toString()
            ),
            totalAmount = CardRequest.TotalAmount(
                    currency = paymentData.currency,
                    paymentAmount = paymentData.total.toString()
            )
          )
        return callTransactionWithShutdown(cardServiceRequest)
    }

Close EFT day:

     fun reconciliationWithClosure(): ServiceResponse {
         val serviceRequest = ServiceRequest(
                    requestType = RequestType.ReconciliationWithClosure.name,
                    workstationID = workstationID,
                    requestID = "0",
                    applicationSender = applicationSender,
                    posData = ServiceRequest.PosData(posTimeStamp = Date())
                  )
         return callTransactionWithShutdown(serviceRequest)
    }

Technical solution

The O.P.I. interface implementation does not depend on a specific operating system. It is an XML-based interface. Communication takes place via TCP/IP. The XML messages are exchanged over two sockets that are referred to as channels (channel 0 and channel 1). The original OPI/IFSF specification defines three message pairs:

Card Request/Response (channel 0) Service Request/Response (channel 0) Device Request/Response (channel 1)

Using the O.P.I. interface gives a payment solution access to the PoS peripherals, e.g. to a PoS printer to print out receipts, a display to output messages to the cashier or cardholder, or a magnetic card reader. Decoupling the interface in this way increases its flexibility for integration in international, solution and industry-specific scenarios for users as well as for PoS and payment solution providers, and therefore also protects their investments.

Communication schema with timeouts