sdk-view-tx

View transactions between layers

This tutorial teaches you how to use the Optimism SDK to view the transactions passed between L1 (Syscoin) and L2 (Rollux) by an address.

Prerequisites

The node script makes these assumptions:

1. You have Node.js running on your computer, as well as yarn.
2. Access to L1 (Syscoin mainnet) and L2 (Rollux) providers.

Running the script

1. Use yarn to download the packages the script needs.

   yarn

2. Copy .env.example to .env and specify the URLs for L1 and L2.

3. Use Node to run the script

   node view-tx.js

Results

Here are the expected results. Note that by the time you read this there might be additional transactions reported.

Deposits by address 0xBCf86Fd70a0183433763ab0c14E7a760194f3a9F
tx:0xa35a3085e025e2addd59c5ef2a2e5529be5141522c3cce78a1b137f2eb992d19
	Amount: 0.01 SYS
	Relayed: true



Withdrawals by address 0xBCf86Fd70a0183433763ab0c14E7a760194f3a9F
tx:0x7826399958c6bb3831ef0b02b658e7e3e69f334e20e27a3c14d7caae545c3d0d
	Amount: 1 DAI
	Relayed: false
tx:0xd9fd11fd12a58d9115afa2ad677745b1f7f5bbafab2142ae2cede61f80e90e8a
	Amount: 0.001 SYS
	Relayed: true

How does it work?

In this section we go over the script line by line to learn how to use the SDK to view deposits and withdrawals.

#! /usr/local/bin/node

// View transfers between L1 and L2 using the Optimism SDK

const ethers = require("ethers")
const optimismSDK = require("@eth-optimism/sdk")
require('dotenv').config()

// Global variable because we need them almost everywhere
let crossChainMessenger


const setup = async() => {

  l1SignerOrProvider = new ethers.providers.JsonRpcProvider(process.env.L1URL)
  l2SignerOrProvider = new ethers.providers.JsonRpcProvider(process.env.L2URL)

  crossChainMessenger = new optimismSDK.CrossChainMessenger({
      l1ChainId: (await l1SignerOrProvider._networkPromise).chainId,
      l2ChainId: (await l2SignerOrProvider._networkPromise).chainId,
      l1SignerOrProvider: l1SignerOrProvider,
      l2SignerOrProvider: l2SignerOrProvider
  })
}    // setup

Create the CrossChainMessenger object that we use to view information. Note that we do not need signers here, since we are only calling view functions. However, we do need the chainId values.

// Only the part of the ABI we need to get the symbol
const ERC20ABI = [
  {
    "constant": true,
    "inputs": [],
    "name": "symbol",
    "outputs": [
        {
            "name": "",
            "type": "string"
        }
    ],
    "payable": false,
    "stateMutability": "view",
    "type": "function"
  }
]     // ERC20ABI



const getSymbol = async l1Addr => {
  if (l1Addr == '0x0000000000000000000000000000000000000000')
    return "SYS"

If l1Addr is all zeroes, it means the transfer was SYS.

  const l1Contract = new ethers.Contract(l1Addr, ERC20ABI, crossChainMessenger.l1SignerOrProvider)
  return await l1Contract.symbol()

Otherwise, ask the contract (we could have used the L1 or the L2) what is the correct symbol.

}   // getSymbol



// Describe a cross domain transaction, either deposit or withdrawal
const describeTx = async tx => {
  console.log(`tx:${tx.transactionHash}`)
  // Assume all tokens have decimals = 18
  console.log(`\tAmount: ${tx.amount/1e18} ${await getSymbol(tx.l1Token)}`)
  console.log(`\tRelayed: ${await crossChainMessenger.getMessageStatus(tx.transactionHash)
                              == optimismSDK.MessageStatus.RELAYED}`)

The result of crossDomainMessenger.getMessageStatus is a MessageStatus enumerated value. In this case we only care whether the deposit/withdrawal is still in process or if it is done.

}  // describeTx


const main = async () => {
    await setup()

    // The address we trace
    const addr = "0xBCf86Fd70a0183433763ab0c14E7a760194f3a9F"

    const deposits = await crossChainMessenger.getDepositsByAddress(addr)

The crossChainMessenger.getDepositsByAddress function gives us all the deposits by an address.

    console.log(`Deposits by address ${addr}`)
    for (var i=0; i<deposits.length; i++)
      await describeTx(deposits[i])

    const withdrawals = await crossChainMessenger.getWithdrawalsByAddress(addr)

The crossChainMessenger.getWithdrawalsByAddress function gives us all the deposits by an address.

    console.log(`\n\n\nWithdrawals by address ${addr}`)
    for (var i=0; i<withdrawals.length; i++)
      await describeTx(withdrawals[i])

}  // main



main().then(() => process.exit(0))
  .catch((error) => {
    console.error(error)
    process.exit(1)
  })

Conclusion

You should now know how to identify all the deposits and/or withdrawals done by a specific address. There are some additional tracing functions in CrossChainMessenger, but they are very similar in operation. Of course, if you have any problems you can ask on our Discord.