Using `viem` to relay interop messages (TypeScript)

This guide describes how to use viem to send and relay interop messages using the L2ToL2CrossDomainMessenger

We'll perform the SuperchainERC20 interop transfer in First steps and Manually relaying interop messages with cast again, this time using viem to relay the message without the autorelayer.

Steps
Full code snippet

Steps

The full code snippet can be found here

1. Start `supersim`

supersim

2. Install TypeScript packages

npm i viem @eth-optimism/viem

3. Imports & Setup

import {
	http,
	encodeFunctionData,
	createWalletClient,
	parseAbi,
	defineChain,
	publicActions,
} from "viem";
import { privateKeyToAccount } from "viem/accounts";
import {
    contracts,
	publicActionsL2,
	walletActionsL2,
    supersimL2A,
    supersimL2B,
    createInteropSentL2ToL2Messages,
    decodeRelayedL2ToL2Messages,
} from "@eth-optimism/viem";

// SuperERC20 is in development so we manually define the address here
const L2_NATIVE_SUPERCHAINERC20_ADDRESS = "0x420beeF000000000000000000000000000000001";

// Account for 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
const account = privateKeyToAccount("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80");

// Define chains
// ... left out as we'll use the supersim chain definitions

// Configure clients with optimism extension
const opChainAClient = createWalletClient({
	transport: http(),
	chain: supersimL2A,
	account,
}).extend(walletActionsL2())
	.extend(publicActionsL2())
	.extend(publicActions);

const opChainBClient = createWalletClient({
	transport: http(),
	chain: superismL2B,
	account,
}).extend(walletActionsL2())
	.extend(publicActionsL2())
	.extend(publicActions);

4. Mint and Bridge `L2NativeSuperchainERC20` from source chain

// #######
// OP Chain A
// #######

// 1. Mint 1000 `L2NativeSuperchainERC20` token on chain A

const mintTxHash = await opChainAClient.writeContract({
	address: L2_NATIVE_SUPERCHAINERC20_ADDRESS,
	abi: parseAbi(["function mint(address to, uint256 amount)"]),
	functionName: "mint",
	args: [account.address, 1000n],
});

await opChainAClient.waitForTransactionReceipt({ hash: mintTxHash });

// 2. Initiate sendERC20 tx to bridge funds to chain B

console.log("Initiating sendERC20 on OPChainA to OPChainB...");
const sendERC20TxHash = await opChainAClient.writeContract({
	address: L2_NATIVE_SUPERCHAINERC20_ADDRESS,
	abi: parseAbi([
		"function sendERC20(address _to, uint256 _amount, uint256 _chainId)",
	]),
	functionName: "sendERC20",
	args: [account.address, 1000n, BigInt(supersimL2B.id)],
});

const sendERC20Receipt = await opChainAClient.waitForTransactionReceipt({ hash: sendERC20TxHash });

// 3. Construct the interoperable log data from the sent message

const { sentMessages } = await createInteropSentL2ToL2Messages(opChainAClient, { receipt: sendERC20Receipt })
const sentMessage = sentMessages[0] // We only sent 1 message

5. Relay the sent message on the destination chain


// ##########
// OP Chain B
// ##########

// 4. Relay the sent message

console.log("Relaying message on OPChainB...");
const relayTxHash = await opChainBClient.relayL2ToL2Message({
    sentMessageId: sentMessage.id,
    sentMessagePayload: sentMessage.payload,
});

const relayReceipt = await opChainBClient.waitForTransactionReceipt({ hash: relayTxHash });

// 5. Ensure the message was relayed successfully

const { successfulMessages, failedMessages } = decodeRelayedL2ToL2Messages({ receipt: relayReceipt });
if (successfulMessages.length != 1) {
    throw new Error("failed to relay message!")
}

// 6. Check balance on OPChainB
const balance = await opChainBClient.readContract({
	address: L2_NATIVE_SUPERCHAINERC20_ADDRESS,
	abi: parseAbi(["function balanceOf(address) view returns (uint256)"]),
	functionName: "balanceOf",
	args: [account.address],
});

console.log(`Balance on OPChainB: ${balance}`);

Full code snippet

Click to view

// Using viem to transfer L2NativeSuperchainERC20

import {
	http,
	encodeFunctionData,
	createWalletClient,
	parseAbi,
	defineChain,
	publicActions,
} from "viem";
import { privateKeyToAccount } from "viem/accounts";
import {
    contracts,
	publicActionsL2,
	walletActionsL2,
    supersimL2A,
    supersimL2B,
    createInteropSentL2ToL2Messages,
    decodeRelayedL2ToL2Messages,
} from "@eth-optimism/viem";

// SuperERC20 is in development so we manually define the address here
const L2_NATIVE_SUPERCHAINERC20_ADDRESS =
	"0x420beeF000000000000000000000000000000001";

// account for 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
const account = privateKeyToAccount("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80");

// Define chains
// ... left out as we'll use the supersim chain definitions

// Configure op clients
const opChainAClient = createWalletClient({
	transport: http(),
	chain: supersimL2A,
	account,
}).extend(walletActionsL2())
	.extend(publicActionsL2())
	.extend(publicActions);

const opChainBClient = createWalletClient({
	transport: http(),
	chain: supersimL2B,
	account,
}).extend(walletActionsL2())
	.extend(publicActionsL2())
	.extend(publicActions);

// #######
// OP Chain A
// #######

// 1. Mint 1000 `L2NativeSuperchainERC20` token

const mintTxHash = await opChainAClient.writeContract({
	address: L2_NATIVE_SUPERCHAINERC20_ADDRESS,
	abi: parseAbi(["function mint(address to, uint256 amount)"]),
	functionName: "mint",
	args: [account.address, 1000n],
});

await opChainAClient.waitForTransactionReceipt({ hash: mintTxHash });

// 2. Initiate sendERC20 tx to bridge funds to chain B

console.log("Initiating sendERC20 on OPChainA...");
const sendERC20TxHash = await opChainAClient.writeContract({
	address: L2_NATIVE_SUPERCHAINERC20_ADDRESS,
	abi: parseAbi([
		"function sendERC20(address _to, uint256 _amount, uint256 _chainId)",
	]),
	functionName: "sendERC20",
	args: [account.address, 1000n, BigInt(supersimL2B.id)],
});

const sendERC20Receipt = await opChainAClient.waitForTransactionReceipt({ hash: sendERC20TxHash });

// 3. Construct the interoperable log data from the sent message

const { sentMessages } = await createInteropSentL2ToL2Messages(opChainAClient, { receipt: sendERC20Receipt })
const sentMessage = sentMessages[0] // We only sent 1 message

// ##########
// OP Chain B
// ##########

// 4. Relay the sent message

console.log("Relaying message on OPChainB...");
const relayTxHash = await opChainBClient.relayL2ToL2Message({
    sentMessageId: sentMessage.id,
    sentMessagePayload: sentMessage.payload,
});

const relayReceipt = await opChainBClient.waitForTransactionReceipt({ hash: relayTxHash });

// 5. Ensure the message was relayed successfully

const { successfulMessages, failedMessages } = decodeRelayedL2ToL2Messages({ receipt: relayReceipt });
if (successfulMessages.length != 1) {
    throw new Error("failed to relay message!")
}

// 6. Check balance on OPChainB
const balance = await opChainBClient.readContract({
	address: L2_NATIVE_SUPERCHAINERC20_ADDRESS,
	abi: parseAbi(["function balanceOf(address) view returns (uint256)"]),
	functionName: "balanceOf",
	args: [account.address],
});

console.log(`Balance on OPChainB: ${balance}`);

Supersim