Implementation Guide

struct Message {    // The version of the origin and destination Mailboxes    uint8 version,    // A nonce to uniquely identify the message on its origin Mailbox    uint32 nonce,    // Domain of origin chain    uint32 origin,    // Address of sender on origin chain    bytes32 sender,    // Domain of destination chain    uint32 destination,    // Address of recipient on destination chain    bytes32 recipient,    // Raw bytes of message body    bytes body}

function dispatch(    // Domain of destination chain    uint32 destination,    // Address of recipient on destination chain as bytes32    bytes32 recipient,    // Raw bytes content of message body    bytes body) returns (    // The message ID inserted into the Mailbox's merkle tree    bytes32 messageId);

function dispatch(    // Domain of destination chain    uint32 destination,    // Address of recipient on destination chain as bytes32    bytes32 recipient,    // Raw bytes content of message body    bytes body,    // Metadata used by the default post dispatch hook    bytes defaultHookMetadata) returns (    // The message ID inserted into the Mailbox's merkle tree    bytes32 messageId);

function dispatch(    // Domain of destination chain    uint32 destination,    // Address of recipient on destination chain as bytes32    bytes32 recipient,    // Raw bytes content of message body    bytes body,    // Metadata used by the custom post dispatch hook    bytes customHookMetadata,    // Custom hook to use instead of the default    IPostDispatchHook customHook) returns (    // The message ID inserted into the Mailbox's merkle tree    bytes32 messageId);

function process(    // Metadata used by the ISM to verify message.    bytes metadata,    // Byte packed message    bytes message);

function latestDispatchedId() public view returns (bytes32);

function handle(    // Domain of origin chain    uint32 origin,    // Address of sender on origin chain    bytes32 sender,    // Raw bytes content of message body    bytes body);

function IInterchainSecurityModule() returns (address);

enum ModuleType {    UNUSED,    ROUTING,    AGGREGATION,    LEGACY_MULTISIG,    MERKLE_ROOT_MULTISIG,    MESSAGE_ID_MULTISIG,    NULL, // used with relayer carrying no metadata    CCIP_READ}function moduleType() returns (ModuleType);

function verify(    // Off-chain metadata provided by a relayer, specific    // to the security model encoded by the module    // (e.g. validator signatures)    bytes metadata,    // Hyperlane encoded interchain message    bytes message) returns (    // True if the message was verified    bool success);

function announce(    address validator,      // The address of the validator    string storageLocation, // Information encoding the location of signed checkpoints    bytes signature         // The signed validator announcement) external returns (bool);

function getAnnouncedStorageLocations(    address[] _validators   // The list of validators to get storage locations for) external view returns (    string[][]              // A list of registered storage metadata);

struct MultisigMetadata {    // The address of the origin mailbox    bytes32 originMailbox;    // The signed checkpoint root    bytes32 signedCheckpointRoot;    // The concatenated signatures of the validators    bytes signatures;}

function validatorsAndThreshold(    // Hyperlane formatted interchain message    bytes message) returns (    // The array of validator addresses    address[] validators,    // The number of validator signatures needed    uint8 threshold);

function payForGas(    // The ID of the message to pay for.    bytes32 messageId,    // The domain of the message's destination chain.    uint32 destination,    // The amount of destination gas to pay for.    uint256 gasAmount,    // The local address to refund any overpayment to.    address refundAddress) payable;

event GasPayment(    bytes32 messageId,    uint32 destinationDomain,    uint256 gasAmount,    uint256 payment);

event DestinationGasConfigSet(    uint32 remoteDomain, // remote domain    address gasOracle,   // gas oracle    uint96 gasOverhead   // destination gas overhead);

pub struct Checkpoint {    /// The mailbox address    pub mailbox_address: H256,    /// The mailbox chain    pub mailbox_domain: u32,    /// The checkpointed root    pub root: H256,    /// The index of the checkpoint    pub index: u32,}

pub struct CheckpointWithMessageId {    /// existing Hyperlane checkpoint struct    #[deref]    pub checkpoint: Checkpoint,    /// hash of message emitted from mailbox checkpoint.index    pub message_id: H256,}

function transferRemote(    // The Domain of the destination chain.    uint32  destination,    // The address of the recipient on the destination chain.    bytes32 recipient,    // The amount or identifier of tokens to be sent to the remote recipient.    uint256 amountOrId) returns (    // The identifier of the dispatched message.    bytes32 messageId);

struct TransferMessage {    // The recipient of the remote transfer    bytes32 recipient;    // An amount of tokens or a token identifier to be transferred    uint256 amountOrId;    // Optional metadata e.g. NFT URI information    bytes   metadata;}