Responders

Implementations of ResponderTxStrategy are used by PartitureResponderFlows to create a SignTransactionFlow with the appropriate verification checks.

Responder APIs are highly unstable. They may be merged to the main flow/TX strategy equivalents, or otherwise change in future versions.

PartitureResponderFlows require a FlowSession given as otherPartySession and a ResponderTxStrategy given as responderTxStrategy.

Consider the YoFlowResponder from our Introduction:

@InitiatedBy(YoFlow::class)
class YoFlowResponder(
        otherPartySession: FlowSession
) : PartitureResponderFlow(
        otherPartySession = otherPartySession,
        responderTxStrategy = 
            SimpleTypeCheckingResponderTxStrategy(YoContract.YoState::class.java)
)

The above responder flow will verify the transaction and ensure all output states are instances of YoState before signing.

Build-in Responder Strategies

Build-in converters reside in the com.github.manosbatsis.partiture.flow.io.output package.

Class	Description
SimpleResponderTxStrategy	Simple responder flow delegate that verifies the (ledger) transaction before signing.
SingleFinalizedTxOutputConverter	Simple responder flow delegate that verifies the (ledger) transaction and ensures all output states are of a certain type(s) before signing.

Custom Responder Strategies

Creating responder TX strategies is a critical part of your application. Here's a template to get you started:

class FooResponderTxStrategy : PartitureResponderFlowDelegateBase(), ResponderTxStrategy {

    /** Create a [SignTransactionFlow] with the appropriate verification checks. */
    @Suspendable
    override fun createSignTransactionFlow(): SignTransactionFlow {
        // Create our custom SignTransactionFlow
        return object : SignTransactionFlow(
                clientFlow.otherPartySession, SignTransactionFlow.tracker()) {
            override fun checkTransaction(stx: SignedTransaction) {
                // Do stuff to ensure the given signed transaction  
                // actually satisfies your requirements:
                return requireThat {itsAllGood()}
            }
        }
    }
}