Send messages from XRPL

In addition to transferring tokens across chains, cross-chain bridges can enable communication between blockchains through general message passing protocols. These protocols allow developers to call functions on other connected chains. For example, smart contracts on EVM-compatible chains, such as the XRPL EVM, can be triggered directly from the XRP Ledger (XRPL), Ethereum, Polygon and other supported chains.

To send a message from one chain to another, there are some key aspects to consider:

• The destination chain must be an EVM-compatible chain, as executing messages requires a smart contract.
• The destination contract must be compatible with the bridge protocol being used (specific interface requirements vary by bridge).

Example: Sending a message using Axelar

Axelar's General Message Passing (GMP) is one protocol that enables cross-chain message passing. With Axelar GMP, developers can call any function on any other connected chain.

Requirements for Axelar

• The destination contract address must inherit from AxelarExecutable

Sending a message from XRP Ledger to XRPL EVM

To send a message from the XRP Ledger (XRPL) to the XRPL EVM, a Payment transaction is used with the following key parameters:

• Amount: Represents the value of the asset to be sent. If the message does not include an asset transfer, this can be set to 1 drop (the smallest XRP unit).
• Destination: The address of the Gateway on the XRP Ledger.
  • Mainnet Address
  • Testnet Address
• Memos: Hex-encoded data required for the function call, including:
  • The type of call to initiate.
  • The destination chain on the Axelar network (xrpl-evm for both Testnet and Mainnet).
  • The contract address on the destination chain to which the message is sent.
  • The payload hash, which contains the data to be sent to the destination contract. This payload must be ABI-encoded. The ethers AbiCoder can be used for encoding the payload.

See Axelar's documentation for a guide on making GMP contract calls.