A Joel Lee's ʕ•ᴥ•ʔ Blog

HowToCrypto: Making an ETH transaction on an Optimistic rollup sidechain

This is a draft!

Intended Audience: Anyone who has an existing Github account. You’ll need a Github account this time so that you can obtain Ether on the Rinkeby test network faucet in order to perform a transaction

Premise: I don’t understand how Blockchain and cryptocurrencies work and I’d like to find out more.

Estimated Reading Time: 2 Minutes

Here’s the list of tasks courtesy of Cedric:

  1. How to buy an ETH domain name
  2. How to do a transaction on Uniswap.
  3. How to get some Synthetix and farm them on layer two
  4. How to do an ETH transaction on an Optimistic rollup sidechain(This post)
  5. How to mint an NFT on OpenSea

What is an Optimistic Rollup Side Chain?

I am oversimplifying here so if you’d like more details please feel free to read the articles linked.

Optimistic Rollup refers to the fact that multiple transactions are rolled up into one. Drawing from the analogy here[1] . Instead of a thousand students each signing one message per day we now have one student signing a thousand messages. It is described as optimistic because it assume that the one student signing messages is telling the truth and nothing but the truth.

A sidechain is a mechanism which allows tokens in one blockchain to be securely used in another blockchain. It also allows for exchange between two blockchains.

Why does this matter?

So now that the term is (somewhat) out of the way let’s go through the steps required to make a transaction. I trawled through the Ethereum docs and eventually settled Offchain Labs and their Arbitrum bridge for developers.

  1. Like before head to the [Rinkeby Faucet](https://faucet.rinkeby.io/) and get some Testnet Ether.

    Rinkeby Testnet Ether

  2. Head to the [Arbitrum website](https://bridge.arbitrum.io/) and deposit some ETH from L1. Deposit some ETH and agree to the confirmation from Metamask. It could take quite a while(in the order of hours) for the transaction to go through.

  3. Head over the [info page](https://bridge.arbitrum.io/#info) and follow the instructions to install a custom RPC. The details are in blue and the option to add a Custom RPC is highlighted in red.

  4. Switch to the ArbRinkeby network and withdraw one ETH. This might take a while(on the order of hours/days)

And… you’re done. That’s all for this series – subsequently I think I’ll be posting more technical posts which deal with how to implement a chain rather than using a chain.

Relevant Links