corda / net.corda.core.flows / AbstractStateReplacementFlow / Instigator

Instigator

abstract class Instigator<out S : ContractState, out T : ContractState, out M> : FlowLogic<StateAndRef<T>>

The Instigator assembles the transaction for state replacement and sends out change proposals to all participants (Acceptor) of that state. If participants agree to the proposed change, they each sign the transaction. Finally, Instigator sends the transaction containing all participants' signatures to the notary for signature, and then back to each participant so they can record it and use the new updated state for future transactions.

Parameters

S - the input contract state type

T - the output contract state type, this can be different from S. For example, in contract upgrade, the output state type can be different from the input state type after the upgrade process.

M - the type of a class representing proposed modification by the instigator.

Types

NOTARY

object NOTARY : Step

SIGNING

object SIGNING : Step

Constructors

<init>

Instigator(originalState: StateAndRef<S>, modification: M, progressTracker: ProgressTracker = Instigator.tracker())

The Instigator assembles the transaction for state replacement and sends out change proposals to all participants (Acceptor) of that state. If participants agree to the proposed change, they each sign the transaction. Finally, Instigator sends the transaction containing all participants' signatures to the notary for signature, and then back to each participant so they can record it and use the new updated state for future transactions.

Properties

modification

val modification: M

originalState

val originalState: StateAndRef<S>

progressTracker

open val progressTracker: ProgressTracker

Override this to provide a ProgressTracker. If one is provided and stepped, the framework will do something helpful with the progress reports e.g record to the audit service. If this flow is invoked as a subflow of another, then the tracker will be made a child of the current step in the parent. If it's null, this flow doesn't track progress.

Inherited Properties

logger

val logger: Logger

This is where you should log things to.

ourIdentity

val ourIdentity: Party

Specifies the identity to use for this flow. This will be one of the multiple identities that belong to this node. This is the same as calling ourIdentityAndCert.party.

ourIdentityAndCert

val ourIdentityAndCert: PartyAndCertificate

Specifies the identity, with certificate, to use for this flow. This will be one of the multiple identities that belong to this node.

runId

val runId: StateMachineRunId

Returns a wrapped java.util.UUID object that identifies this state machine run (i.e. subflows have the same identifier as their parents).

serviceHub

val serviceHub: ServiceHub

Provides access to big, heavy classes that may be reconstructed from time to time, e.g. across restarts. It is only available once the flow has started, which means it cannot be accessed in the constructor. Either access this lazily or from inside call.

Functions

assembleTx

abstract fun assembleTx(): UpgradeTx

Build the upgrade transaction.

call

open fun call(): StateAndRef<T>

This is where you fill out your business logic.

getParticipantSessions

open fun getParticipantSessions(): List<Pair<FlowSession, List<AbstractParty>>>

Initiate sessions with parties we want signatures from.

Inherited Functions

checkFlowPermission

fun checkFlowPermission(permissionName: String, extraAuditData: Map<String, String>): Unit

Flows can call this method to ensure that the active FlowInitiator is authorised for a particular action. This provides fine grained control over application level permissions, when RPC control over starting the flow is insufficient, or the permission is runtime dependent upon the choices made inside long lived flow code. For example some users may have restricted limits on how much cash they can transfer, or whether they can change certain fields. An audit event is always recorded whenever this method is used. If the permission is not granted for the FlowInitiator a FlowException is thrown.

flowStackSnapshot

fun flowStackSnapshot(): FlowStackSnapshot?

Returns a shallow copy of the Quasar stack frames at the time of call to flowStackSnapshot. Use this to inspect what objects would be serialised at the time of call to a suspending action (e.g. send/receive). Note: This logic is only available during tests and is not meant to be used during the production deployment. Therefore the default implementation does nothing.

getFlowInfo

fun getFlowInfo(otherParty: Party): FlowInfo

Returns a FlowInfo object describing the flow otherParty is using. With FlowInfo.flowVersion it provides the necessary information needed for the evolution of flows and enabling backwards compatibility.

initiateFlow

fun initiateFlow(party: Party): FlowSession

Creates a communication session with party. Subsequently you may send/receive using this session object. Note that this function does not communicate in itself, the counter-flow will be kicked off by the first send/receive.

persistFlowStackSnapshot

fun persistFlowStackSnapshot(): Unit

Persists a shallow copy of the Quasar stack frames at the time of call to persistFlowStackSnapshot. Use this to track the monitor evolution of the quasar stack values during the flow execution. The flow stack snapshot is stored in a file located in {baseDir}/flowStackSnapshots/YYYY-MM-DD/{flowId}/ where baseDir is the node running directory and flowId is the flow unique identifier generated by the platform.

receive

fun <R : Any> receive(otherParty: Party): UntrustworthyData<R>

Suspends until the specified otherParty sends us a message of type R.

open fun <R : Any> receive(receiveType: Class<R>, otherParty: Party): UntrustworthyData<R>

Suspends until the specified otherParty sends us a message of type receiveType.

receiveAll

open fun <R : Any> receiveAll(receiveType: Class<R>, sessions: List<FlowSession>, maySkipCheckpoint: Boolean = false): List<UntrustworthyData<R>>

Suspends until a message has been received for each session in the specified sessions.

receiveAllMap

open fun receiveAllMap(sessions: Map<FlowSession, Class<out Any>>, maySkipCheckpoint: Boolean = false): Map<FlowSession, UntrustworthyData<Any>>

Suspends until a message has been received for each session in the specified sessions.

recordAuditEvent

fun recordAuditEvent(eventType: String, comment: String, extraAuditData: Map<String, String>): Unit

Flows can call this method to record application level flow audit events

send

open fun send(otherParty: Party, payload: Any): Unit

Queues the given payload for sending to the otherParty and continues without suspending.

sendAndReceive

fun <R : Any> sendAndReceive(otherParty: Party, payload: Any): UntrustworthyData<R>

Serializes and queues the given payload object for sending to the otherParty. Suspends until a response is received, which must be of the given R type.

open fun <R : Any> sendAndReceive(receiveType: Class<R>, otherParty: Party, payload: Any): UntrustworthyData<R>

Serializes and queues the given payload object for sending to the otherParty. Suspends until a response is received, which must be of the given receiveType. Remember that when receiving data from other parties the data should not be trusted until it's been thoroughly verified for consistency and that all expectations are satisfied, as a malicious peer may send you subtly corrupted data in order to exploit your code.

subFlow

open fun <R> subFlow(subLogic: FlowLogic<R>): R

Invokes the given subflow. This function returns once the subflow completes successfully with the result returned by that subflow's call method. If the subflow has a progress tracker, it is attached to the current step in this flow's progress tracker.

track

fun track(): DataFeed<String, String>?

Returns a pair of the current progress step, as a string, and an observable of stringified changes to the progressTracker.

trackStepsTree

fun trackStepsTree(): DataFeed<List<Pair<Int, String>>, List<Pair<Int, String>>>?

Returns a pair of the current steps tree of current progressTracker as pairs of zero-based depth and stringified step label and observable of upcoming changes to the structure.

trackStepsTreeIndex

fun trackStepsTreeIndex(): DataFeed<Int, Int>?

Returns a pair of the current progress step index (as integer) in steps tree of current progressTracker, and an observable of its upcoming changes.

waitForLedgerCommit

fun waitForLedgerCommit(hash: SecureHash, maySkipCheckpoint: Boolean = false): SignedTransaction

Suspends the flow until the transaction with the specified ID is received, successfully verified and sent to the vault for processing. Note that this call suspends until the transaction is considered valid by the local node, but that doesn't imply the vault will consider it relevant.

waitForStateConsumption

fun waitForStateConsumption(stateRefs: Set<StateRef>): Unit

Suspends the current flow until all the provided StateRefs have been consumed.

Companion Object Functions

tracker

fun tracker(): ProgressTracker

Inheritors

Initiate

class Initiate<OldState : ContractState, out NewState : ContractState> : Instigator<OldState, NewState, Class<out UpgradedContract<OldState, NewState>>>

This flow begins the contract upgrade process.

NotaryChangeFlow

class NotaryChangeFlow<out T : ContractState> : Instigator<T, T, Party>

A flow to be used for changing a state's Notary. This is required since all input states to a transaction must point to the same notary.