Issue regarding repayment feature - corda

Question

I’m new to Corda. Is there a direct way to execute a repayment as a subflow on the other side back to the sender of a certain amount of cash, when directly calling the recipient node within the CashPaymentFlow, e.g. something like this:
recipient.run {
subFlow(CashPaymentFlow(amount, sender ,anonymous))
}
(This is not working, it’s just an example). I need a more dynamic solution for using it within the demobench. The recipient node for the initital payment is chosen from the demobench UI. The problem is to automatically call or reference to the other side’s node and ask it to execute a repayment (by using e.g. the cashPaymentFlow), when executing the initial payment from the sender side. I now that I can manually “go” to the receiver node and execute a payment back to the sender via the UI or terminal, but this is not the intention.

Answer 1

You can achieve this by making the repayment part of the same flow as the initial payment, as follows:
#InitiatingFlow
#StartableByRPC
class Payer(val initialAmount: Amount<Currency>, val changeAmount: Amount<Currency>, val recipient: Party) : FlowLogic<Unit>() {
#Suspendable
override fun call() {
subFlow(CashPaymentFlow(initialAmount, recipient))
val sessionWithRecipient = initiateFlow(recipient)
sessionWithRecipient.send(changeAmount)
}
}
#InitiatedBy(Payer::class)
class Recipient(val payerSession: FlowSession) : FlowLogic<Unit>() {
#Suspendable
override fun call() {
val changeAmount = payerSession.receive<Amount<Currency>>().unwrap { it }
subFlow(CashPaymentFlow(changeAmount, payerSession.counterparty))
}
}

Answer 2

I would like to pass another variable along with ‘changeAmount’. Is this possible? I tried doing it this way:
#InitiatingFlow
#StartableByRPC
class Payer(val initialAmount: Amount<Currency>, val changeAmount:Amount<Currency>, val recipient: Party) : FlowLogic<Unit>() {
#Suspendable
override fun call() {
subFlow(CashPaymentFlow(initialAmount, recipient))
val sessionWithRecipient = initiateFlow(recipient)
sessionWithRecipient.send(changeAmount)
sessionWithRecipient.send(delay) //second variable
}
}
#InitiatedBy(Payer::class)
class Recipient(val payerSession: FlowSession) : FlowLogic<Unit>() {
#Suspendable
override fun call() {
val changeAmount = payerSession.receive<Amount<Currency>>().unwrap { it }
val delay = payerSession.receive<Duration>().unwrap { it }
for (i in 1..10) //the 10 automated paybacks
{subFlow(CashPaymentFlow(changeAmount, payerSession.counterparty))
sleep(delay)} //usage of the second variable
}
}