Demo Cross-Chain contract Swisstronik <-> Mumbai

Overview

This project demonstrates basic Cross-Chain contract which is using Hyperlane Mailbox to broadcast messages across chains.

The contract itself can be found here: SampleCrossChainCounter.sol

Build

Install dependencies:

npm install

Compile contracts:

npm run compile

Deploy

We will deploy 2 instances of SampleCrossChainCounter, one in Swisstronik and one in Polygon Mumbai.

Before deployment, create .env file by running the following command:

cp .env.sample .env

Then, in .env file, fill DEPLOYER_KEY env var with private key, which will be used to deploy contracts in both networks. Account, associated with this private key, should be funded in both networks.

Optional -

When .env file is fulfilled, you can deploy contracts using the following command:

npm run deploy

Command above will output you contract addresses in both networks. If you want, you can use those custom deployed contracts with your .env file.

Interact

We've prepared multiple scripts for interaction with deployed contracts.

You can use these scripts with already deployed contracts. However,if you wish you can deploy your own and update contract addresses in .env file to addresses of deployed contracts.

• MUMBAI_CONTRACT_ADDRESS should be filled with address of SampleCrossChainCounter deployed in Polygon Mumbai
• SWISSTRONIK_CONTRACT_ADDRESS should be filled with address of SampleCrossChainCounter deployed in Swisstronik

Increment counter in Polygon Mumbai

We will start from incrementing counter in Polygon Mumbai network. You can use the command below:

npm run increment:mumbai

The command above will output you previous and new value of counter. During the counter update, the contract calls dispatch function at Hyperlane Mailbox to increment value at Swisstronik SampleCrossChainCounter instance also.

The cross-chain transaction takes about 1 minute. You can check, if cross-chain transaction was succeed by checking state of Swisstronik's instance. You can use command below to check counter state in Swisstronik:

npm run counter:swisstronik

Increment counter in Swisstronik Network

To increment counter in Swisstronik and sync its value with Mumbai instance, you can use the following command:

npm run increment:swisstronik

The command above works the same as in Polygon Mumbai, but now Swisstronik instance calls Hyperlane Mailbox, deployed in Swisstronik, to initiate cross-chain transaction.

You can check if cross-chain transaction from Swisstronik to Mumbai was succeed by running the following command:

npm run counter:mumbai