Greeter

Check out this tutorial on GitHub: greeter

greeter is a simple demo of Arbitrum’s Parent-to-child message passing system (aka “L1-to-L2” or “retryable tickets”).

It deploys 2 contracts - one to the parent chain, and another to the child chain, and has the parent chain contract send a message to the child chain contract to be executed automatically.

The script and contracts demonstrate how to interact with Arbitrum’s core bridge contracts to create these retryable messages, how to calculate and forward appropriate fees from parent to child, and how to use Arbitrum’s Parent-to-child message address aliasing.

See exec.py for inline explanation.

Click here for more info on retryable tickets.

Set environment variables

Set the values shown in .env-sample as environmental variables. To copy it into a .env file:

cp .env-sample .env

You’ll still need to edit some variables, i.e., PRIVATE_KEY, CHAIN_RPC and PARENT_CHAIN_RPC.

Note that you can also set the environment variables in an .env file in the root of the monorepo, which will be available in all tutorials.

Run

Install dependencies and build the contracts:

chmod +x ./build.sh && ./build.sh

Run the script:

python3 scripts/exec.py