Optimism Messenger L1->L2 Example

Send a message from L1 Goerli to L2 Optimism testnet.

Example

There's two contracts; L2Contract.sol and L1Contract.sol

The L1 contract has a method sendMessageToL2 that sends a message from L1 to L2 contract to set a greeting message on L2 contract. It sends the encoded calldata to execute setGreeting on L2 which can only be called if the message was sent by the L1 contract.

Files

• L2Contract.sol
• L1Contract.sol
• deployL2.js
• deployL1.js
• sendL1ToL2Message.js
• waitForInclusion.js
• getGreetingOnL2.js

Install

git clone https://github.com/miguelmota/optimism-messenger-l1-to-l2-example.git
cd optimism-messenger-l1-to-l2-example
npm install

Set Signer

Create .env

PRIVATE_KEY=123...

Make sure private key has funds on both Goerli and Optimism testnet.

Compile Contracts

npx hardhat compile

Deploy L1 Contract

Command

npx hardhat run --network goerli scripts/deployL1.js

Output

L1Contract deployed to: 0x21DEC68E1D07B3cC138A5b70063cC744793865e5

Deploy L2 Contract

Command

L1_CONTRACT=0x21DEC68E1D07B3cC138A5b70063cC744793865e5 \
npx hardhat run --network optimism scripts/deployL2.js

Output

L2Contract deployed to: 0x0bbe3d35D1aA220ad238f578E7720dA4a1FdC30C

Send L1->L2 Message

Command (replace env vars with your values)

GREETING="hello world" \
L1_CONTRACT=0x21DEC68E1D07B3cC138A5b70063cC744793865e5 \
L2_CONTRACT=0x0bbe3d35D1aA220ad238f578E7720dA4a1FdC30C \
npx hardhat run --network goerli scripts/sendL1ToL2Message.js

Output

sent tx hash 0xadf720ae44585f5244afc2050c09469a2d55d4ea559e0620fe92fa6733b2bf71
https://goerli.etherscan.io/tx/0xadf720ae44585f5244afc2050c09469a2d55d4ea559e0620fe92fa6733b2bf71

Wait for L2 Root Inclusion

Command

L1_TX_HASH=0xadf720ae44585f5244afc2050c09469a2d55d4ea559e0620fe92fa6733b2bf71 \
npx hardhat run --network optimism scripts/waitForInclusion.js

Output

Waiting for L2 root inclusion (this may take up to 5 minutes)...
L2 root inclusion confirmed
L2 message relayed

Get Greeting on L2

Command

L2_CONTRACT=0x0bbe3d35D1aA220ad238f578E7720dA4a1FdC30C \
npx hardhat run --network optimism scripts/getGreetingOnL2.js

Output

greeting: hello world

Send L2->L1 Message

See https://github.com/miguelmota/optimism-messenger-l2-to-l1-example

License

MIT @ Miguel Mota