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L1-L2 Postman integration

Postman is a Starknet utility that allows testing L1 <-> L2 interaction. To utilize this, you can use starknet-hardhat-plugin, as witnessed in this example. Or you can directly interact with the two Postman-specific endpoints:

Postman - Load​

POST /postman/load_l1_messaging_contract
{
  "networkUrl": "http://localhost:8545",
  "address": "0x123...def"
}

Loads a MockStarknetMessaging contract. The address parameter is optional; if provided, the MockStarknetMessaging contract will be fetched from that address, otherwise a new one will be deployed.

networkUrl is the URL of the JSON-RPC API of the L1 node you've run locally or that already exists; possibilities include, and are not limited to:

Postman - Flush​

POST /postman/flush

Goes through the newly enqueued messages, sending them from L1 to L2 and from L2 to L1. Requires no body.

Postman - disclaimer​

This method of L1 <-> L2 communication testing differs from Starknet Alpha networks. Taking the L1L2Example.sol contract from the Starknet documentation:

constructor(IStarknetCore starknetCore_) public {
    starknetCore = starknetCore_;
}

The constructor takes an IStarknetCore contract as argument, however for Devnet L1 <-> L2 communication testing, this will have to be replaced with the MockStarknetMessaging.sol contract :

constructor(MockStarknetMessaging mockStarknetMessaging_) public {
    starknetCore = mockStarknetMessaging_;
}

Postman - l1 to l2 mock endpoint​

Sending mock transactions from L1 to L2 without the need for running L1. Deployed L2 contract address l2_contract_address and entry_point_selector must be valid otherwise new block will not be created.

Normally nonce is calculated by L1 StarknetContract and it's used in L1 and L2. In this case, we need to provide it manually.

POST /postman/send_message_to_l2

Request:

{
    "l2_contract_address": "0x00285ddb7e5c777b310d806b9b2a0f7c7ba0a41f12b420219209d97a3b7f25b2",
    "entry_point_selector": "0xC73F681176FC7B3F9693986FD7B14581E8D540519E27400E88B8713932BE01",
    "l1_contract_address": "0xe7f1725E7734CE288F8367e1Bb143E90bb3F0512",
    "payload": [
      "0x1",
      "0x2"
    ],
    "paid_fee_on_l1": "0x123456abcdef"
    "nonce":"0x0"
}

Response:

{"transaction_hash": "0x0548c761a9fd5512782998b2da6f44c42bf78fb88c3794eea330a91c9abb10bb"}

Postman - l2 to l1 mock endpoint​

Sending mock transactions from L2 to L1. Deployed L2 contract address l2_contract_address and l1_contract_address must be valid.

POST /postman/consume_message_from_l2

Request:

{
    "l2_contract_address": "0x00285ddb7e5c777b310d806b9b2a0f7c7ba0a41f12b420219209d97a3b7f25b2",
    "l1_contract_address": "0xe7f1725E7734CE288F8367e1Bb143E90bb3F0512",
    "payload": ["0x0", "0x1", "0x3e8"],
}

Response:

{"message_hash": "0xae14f241131b524ac8d043d9cb4934253ac5c5589afef19f0d761816a9c7e26d"}