cross-chain-atomic-swap-cordapp

Cross-Chain Atomic Swap Cordapp

This CorDapp provides a simple example of Cross-Chain Atomic Swap between Corda and EVM based Blockchain without trusted third party.

Be aware that support of HTTP requests in flows is currently limited:

• The request must be executed in a BLOCKING way. Flows don't currently support suspending to await an HTTP call's response
• The request must be idempotent. If the flow fails and has to restart from a checkpoint, the request will also be replayed

Also, be aware that there is okhttp's dependency conflict between Corda Node v4 and web3j (later than 4.5.12).

Pre-requisites

See https://docs.corda.net/getting-set-up.html.

Run database

docker run --name postgres96 -e POSTGRES_PASSWORD=password -p 5432:5432 -d postgres:9.6

// clean up the container after stop
docker run --rm --name postgres96-rm -e POSTGRES_PASSWORD=password -p 5432:5432 -d postgres:9.6

Deploy Settlement contract on Ethereum

ganache-cli is a fast Ethereum RPC client for testing and development.

You can run ganache-cli and deploy Settlement contract by following Atomic Swap Ethereum Environment.

Create SmartContract Wrapper Class by web3j command

You need to install Web3j CLI first.

Then, you can generate the wrapper class

web3j truffle generate ../atomic-swap-ethereum-env/build/contracts/Settlement.json -o ./src/main/java -p jp.co.layerx.cordage.crosschainatomicswap.ethWrapper

Usage

Running the nodes

See https://docs.corda.net/tutorial-cordapp.html#running-the-example-cordapp.

Use the deployNodes task and ./build/nodes/runnodes script.

UAT scenario

Assumption to participants

There are 3 participants.

Party C is an issuer of CorporateBond.

Party A wants to buy 100 amount of corporate bond that is owned by Party B.

• Party A remits by ether to Party B (The unit price is specified with the initial CorporateBond registration)
• Party B transfers 100 amount of corporate bond to Party A

This is expected to happen in an atomic way.

Existing processes (nodes)

Several processes (nodes) exist in this scenario.

• Party A's Corda Node
• Party B's Corda Node
• Party C's Corda Node
• Corda Notary; run with PostgreSQL
• Ethereum Node; you may easily run by Ganache CLI

Every Data propagation between Corda and Ethereum is executed by Corda Nodes or Notary. Other processes are not required.

Setup

Register CorporateBond from Party C

flow start jp.co.layerx.cordage.crosschainatomicswap.flow.CorporateBondRegisterFlow name: "LayerX", unitPriceEther: "0.012345678901234567", observer: "O=ParticipantA,L=London,C=GB"

at the same time, CorporateBond state is shared to Party A to notify the unit price of the corporate bond.

Then, get the linearId of CorporateBond

run vaultQuery contractStateType: jp.co.layerx.cordage.crosschainatomicswap.state.CorporateBond

Issue CorporateBond from PartyC to Party B

flow start jp.co.layerx.cordage.crosschainatomicswap.flow.CorporateBondIssueFlow linearId: "52a6335d-f71e-43aa-86c4-696afdee0fdd", quantity: 1000, holder: "O=ParticipantB,L=New York,C=US"

Then, you can check issued CorporateBond token by running below from Party B

run vaultQuery contractStateType: com.r3.corda.lib.tokens.contracts.states.FungibleToken

Propose Cross-Chain Atomic Swap

Run ProposeAtomicSwapFlow from ParticipantA with corporateBondLinearId:

flow start jp.co.layerx.cordage.crosschainatomicswap.flow.ProposeAtomicSwapFlow corporateBondLinearId: "52a6335d-f71e-43aa-86c4-696afdee0fdd", quantity: 100, swapId: "3", acceptor: "O=ParticipantB,L=New York,C=US", fromEthereumAddress: "0xFFcf8FDEE72ac11b5c542428B35EEF5769C409f0", toEthereumAddress: "0x22d491Bde2303f2f43325b2108D26f1eAbA1e32b", mockLockEtherFlow: null

The acceptor ParticipantB can validate this Proposal with checkTransaction() in ProposeAtomicSwapFlowResponder. The proposer ParticipantA will lock Ether to Settlement Contract in subflow.

vaultQuery for Proposal State

run vaultQuery contractStateType: jp.co.layerx.cordage.crosschainatomicswap.state.ProposalState

You can get linearId of Proposal State by the result.

Start EventWatchFlow

Go to the CRaSH shell for ParticipantB, and run the StartEventWatchFlow with proposalStateLinearId:

flow start jp.co.layerx.cordage.crosschainatomicswap.flow.StartEventWatchFlow proposalStateLinearId: "c8944c30-3db1-4e76-a0e2-1d06269d6bac"

You can now start monitoring the node's flow activity...

flow watch

...you will see the EventWatch flow running every 10 seconds until you close the Flow Watch window using ctrl/cmd + c:

xxxxxxxx-xxxx-xxxx-xx Event Watch xxxxxxxxxxxxxxxxxxxx    Event Watched. (fromBlockNumber: x, toBlockNumber: xxxx)

...Or if aimed Ethereum Event was emitted on Ethereum network, EventWatch flow will end with below log:

xxxxxxxx-xxxx-xxxx-xx Event Watch xxxxxxxxxxxxxxxxxxxx    SettleAtomicSwapFlow has executed with xxxx securities.

Abort Proposal State (This is executed instead of StartEventWatchFlow)

Run AbortAtomicSwapFlow from Proposer(ParticipantA) with ProposalState's linearId:

flow start jp.co.layerx.cordage.crosschainatomicswap.flow.AbortAtomicSwapFlow proposalStateLinearId: "c8944c30-3db1-4e76-a0e2-1d06269d6bac"

The Notary will unlock Ether to ParticipantA's Ethereum address.