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negotiation-cordapp

README.md

Negotiation Cordapp

This CorDapp shows how multi-party negotiation is handled on the Corda ledger, in the absence of an API for user interaction.

Concepts

A flow is provided that allows a node to propose a trade to a counterparty. The counterparty has two options:

  • Accepting the proposal, converting the ProposalState into a TradeState with identical attributes
  • Modifying the proposal, consuming the existing ProposalState and replacing it with a new ProposalState for a new amount

Only the recipient of the proposal has the ability to accept it or modify it. If the sender of the proposal tries to accept or modify the proposal, this attempt will be rejected automatically at the flow level.

Flows

We start with the proposal flow implemented in ProposalFlow.kt.

The modification of the proposal is implemented in ModificationFlow.kt.

In the AcceptanceFlow.java, we receive the modified ProposalState and it's converted into a TradeState.

Usage

Pre-Requisites

Set up for CorDapp development

Running the nodes:

Open a terminal and go to the project root directory and type: (to deploy the nodes using bootstrapper)

./gradlew clean deployNodes

Then type: (to run the nodes)

./build/nodes/runnodes

We will interact with this CorDapp via the nodes' CRaSH shells.

First, go the the shell of PartyA, and propose a deal with yourself as buyer and a value of 10 to PartyB:

flow start ProposalFlow$Initiator isBuyer: true, amount: 10, counterparty: PartyB

We can now look at the proposals in the PartyA's vault:

run vaultQuery contractStateType: net.corda.samples.negotiation.states.ProposalState

If we note down the state's linearId.id, we can now modify the proposal from the shell of PartyB by running:

flow start ModificationFlow$Initiator proposalId: <YOUR-NEWLY-GENERATED-PROPOSAL-ID>, newAmount: 8

Finally, let's have PartyA accept the proposal:

flow start AcceptanceFlow$Initiator proposalId: <YOUR-NEWLY-GENERATED-PROPOSAL-ID>

We can now see the accepted trade in our vault with the new value by running the command (note we are now querying for TradeStates, not ProposalStates):

run vaultQuery contractStateType: net.corda.samples.negotiation.states.TradeState