如何在同一流程中多次获得同一交易对手的签名

Question

我需要实现这样的场景：有CentralParty、PartyA、PartyB。CentralParty需要发起一个流程，其中一个循环中有3笔交易，其中发起方始终是Central party，另一方将是甲方2次。

也就是说，我正试图通过参考以下链接，从同一交易对手处多次从单一流程中收集签名

Corda返回单个流调用中的多个事务((

val flowSessionMap = mutableMapOf<Party, FlowSession>()
var ftx:MutableList<SignedTransaction> = mutableListOf<SignedTransaction>()
var signedTransaction:SignedTransaction
val fullySignedTransactions = matchingStateList.forEach { matchingState ->
val txCommand = Command(IOUContract.Commands.Matching(), matchingState.participants.map { it.owningKey })
val txBuilder = TransactionBuilder(notary)
.addOutputState(matchingState, IOU_CONTRACT_ID)
.addCommand(txCommand)
// Stage 2.
progressTracker.currentStep = VERIFYING_TRANSACTION
// Verify that the transaction is valid.
txBuilder.verify(serviceHub)
// Stage 3.
progressTracker.currentStep = SIGNING_TRANSACTION
// Sign the transaction.
val partSignedTx = serviceHub.signInitialTransaction(txBuilder, ourIdentity.owningKey)

val sessions = (listOf(PartyA).map { signer ->
flowSessionMap.getOrPut(signer) {
initiateFlow(signer)
}
})
val fullySignedTransaction = subFlow(CollectSignaturesInitiatingFlow(
partSignedTx, sessions)
)
signedTransaction = fullySignedTransaction
ftx.add(signedTransaction)
}
for (transaction in ftx) {
subFlow(FinalityFlow(transaction))
}

响应程序流定义如下：

class Acceptor(val otherPartyFlow: FlowSession) : FlowLogic<SignedTransaction>() {
@Suspendable
override fun call(): SignedTransaction {
val signTransactionFlow = object : SignTransactionFlow(otherPartyFlow) {
override fun checkTransaction(stx: SignedTransaction) = requireThat {
val output = stx.tx.outputs.single().data
"This must be an Matching State transaction." using (output is MatchingState)
val Match = output as MatchingState
"I won't accept IOUs with a value over 100." using (iou.value <= 100)
}
}
return subFlow(signTransactionFlow)
}
}

CollectSignaturesInitiatingFlow定义如下：

@InitiatingFlow
class CollectSignaturesInitiatingFlow(val signedTransaction: SignedTransaction, val sessions: List<FlowSession>): FlowLogic<SignedTransaction>() {
override fun call(): SignedTransaction {
return subFlow(CollectSignaturesFlow(signedTransaction, sessions))
}
}

CollectSignaturesInitiatingFlow的响应程序定义如下：

@InitiatedBy(CollectSignaturesInitiatingFlow::class)
class CollectSignaturesInitiatingFlowResponder(val otherPartyFlow: FlowSession) : FlowLogic<SignedTransaction>() {
@Suspendable
override fun call(): SignedTransaction {
val signTransactionFlow = object : SignTransactionFlow(otherPartyFlow) {
override fun checkTransaction(stx: SignedTransaction) {
TODO("Check the transaction here.")
}
}
return subFlow(signTransactionFlow)
}
}

在运行相同的代码时，我遇到了类似的错误

[WARN ] 15:43:18,817 [Node thread-1] (FlowStateMachineImpl.kt:111) flow.[82900238-9223-4ace-ba78-9ecc45121b11].run - Terminated by unexpected exception {}
net.corda.core.flows.UnexpectedFlowEndException: Counterparty flow on O=PartyA, L=London, C=GB has completed without sending data
at net.corda.node.services.statemachine.FlowStateMachineImpl.confirmNoError(FlowStateMachineImpl.kt:488) ~[corda-node-3.2-corda.jar:?]
at net.corda.node.services.statemachine.FlowStateMachineImpl.waitForMessage(FlowStateMachineImpl.kt:444) ~[corda-node-3.2-corda.jar:?]
at net.corda.node.services.statemachine.FlowStateMachineImpl.sendAndReceiveInternal(FlowStateMachineImpl.kt:385) ~[corda-node-3.2-corda.jar:?]
at net.corda.node.services.statemachine.FlowStateMachineImpl.sendAndReceive(FlowStateMachineImpl.kt:203) ~[corda-node-3.2-corda.jar:?]
at net.corda.node.services.statemachine.FlowSessionImpl.sendAndReceive(FlowSessionImpl.kt:29) ~[corda-node-3.2-corda.jar:?]
at net.corda.node.services.statemachine.FlowSessionImpl.sendAndReceive(FlowSessionImpl.kt:40) ~[corda-node-3.2-corda.jar:?]
at net.corda.core.flows.DataVendingFlow.sendPayloadAndReceiveDataRequest(SendTransactionFlow.kt:70) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.DataVendingFlow.call(SendTransactionFlow.kt:48) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.DataVendingFlow.call(SendTransactionFlow.kt:31) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:290) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.CollectSignatureFlow.call(CollectSignaturesFlow.kt:142) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.CollectSignatureFlow.call(CollectSignaturesFlow.kt:135) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:290) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.CollectSignaturesFlow.call(CollectSignaturesFlow.kt:114) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.CollectSignaturesFlow.call(CollectSignaturesFlow.kt:64) ~[corda-core-3.2-corda.jar:?]
at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:290) ~[corda-core-3.2-corda.jar:?]
at com.example.flow.ExampleFlowMatching$CollectSignaturesInitiatingFlow.call(ExampleFlowMatching.kt:260) ~[classes/:?]
at com.example.flow.ExampleFlowMatching$CollectSignaturesInitiatingFlow.call(ExampleFlowMatching.kt:258) ~[classes/:?]
at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:290) ~[corda-core-3.2-corda.jar:?]
at com.example.flow.ExampleFlowMatching$ExampleFlowMatchingInitiator.call(ExampleFlowMatching.kt:202) ~[classes/:?]
at com.example.flow.ExampleFlowMatching$ExampleFlowMatchingInitiator.call(ExampleFlowMatching.kt:45) ~[classes/:?]
at net.corda.node.services.statemachine.FlowStateMachineImpl.run(FlowStateMachineImpl.kt:96) [corda-node-3.2-corda.jar:?]
at net.corda.node.services.statemachine.FlowStateMachineImpl.run(FlowStateMachineImpl.kt:44) [corda-node-3.2-corda.jar:?]
at co.paralleluniverse.fibers.Fiber.run1(Fiber.java:1092) [quasar-core-0.7.9-jdk8.jar:0.7.9]
at co.paralleluniverse.fibers.Fiber.exec(Fiber.java:788) [quasar-core-0.7.9-jdk8.jar:0.7.9]
at co.paralleluniverse.fibers.RunnableFiberTask.doExec(RunnableFiberTask.java:100) [quasar-core-0.7.9-jdk8.jar:0.7.9]
at co.paralleluniverse.fibers.RunnableFiberTask.run(RunnableFiberTask.java:91) [quasar-core-0.7.9-jdk8.jar:0.7.9]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_191]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_191]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_191]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:1.8.0_191]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_191]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_191]
at net.corda.node.utilities.AffinityExecutor$ServiceAffinityExecutor$1$thread$1.run(AffinityExecutor.kt:62) [corda-node-3.2-corda.jar:?]

Answer 1

问题是您在主流ExampleFlowMatchingInitiator中而不是在CollectSignaturesInitiatingFlow中启动流会话。

当您调用initiateFlow时，它会在当前InitiatingFlow的上下文中启动与交易对手的流会话。因此，当您在ExampleFlowMatchingInitiator中呼叫initiateFlow时，交易对手将检查是否有注册ExampleFlowMatchingInitiator的响应者。它确实是Acceptor，所以它启动一个流会话，使用Acceptor与交易对手对话。

如果您改为在CollectSignaturesInitiatingFlow内部呼叫initiateFlow，交易对手将检查是否有注册CollectSignaturesInitiatingFlow的响应者。它确实是CollectSignaturesInitiatingFlowResponder，所以它启动了一个流会话，转而使用CollectSignaturesInitiatingFlowResponder与交易对手对话。