EVM Blockchains

To interact with universal apps from EVM chains (like Ethereum, BNB, Polygon, etc.) use the EVM gateway.

EVM gateway supports:

• depositing gas tokens to a universal app or an account on ZetaChain
• depositing supported ERC-20 tokens (including ZETA tokens)
• depositing gas tokens and calling a universal app
• depositing supported ERC-20 tokens and calling a universal app
• calling a universal app

Deposit Gas Tokens

To deposit tokens to an EOA or a universal contract call the deposit function of the Gateway contract.

deposit(address receiver, RevertOptions calldata revertOptions) external payable;

The deposit function is payable, which means it accepts native gas tokens (for example, ETH on Ethereum), which will then be sent to a receiver on ZetaChain.

The receiver is either an externally-owned account (EOA) or a universal app address on ZetaChain. Even if the receiver is a universal app contract with the standard receive function, the deposit function will not trigger a contract call. If you want to deposit and call a universal app, please, use the depositAndCall function, instead.

After the deposit is processed, the receiver gets ZRC-20 version of the deposited token, for example (ZRC-20 ETH).

Deposit ERC-20 Tokens

The deposit function can also be used to send supported ERC-20 tokens to EOAs and universal apps on ZetaChain.

deposit(address receiver, uint256 amount, address asset, RevertOptions calldata revertOptions) external;

Only supported ERC-20 assets can be deposited. The receiver gets ZRC-20 version of the deposited token (for example, ZRC-20 USDC.ETH).

The amount is the amount and asset is the token address of the ERC-20 that is being deposited.

Deposit Gas Tokens and Call a Universal App

To deposit tokens and call a universal app contract use the depositAndCall function.

depositAndCall(address receiver, bytes calldata payload, RevertOptions calldata revertOptions) external payable;

After the cross-chain transaction is processed, the onCall function of a universal app contract is executed.

The receiver must be a universal app contract address.

pragma solidity 0.8.7;
 
import "@zetachain/protocol-contracts/contracts/zevm/interfaces/zContract.sol";
 
contract UniversalApp is UniversalContract {
    function onCall(
        MessageContext calldata context,
        address zrc20,
        uint256 amount,
        bytes calldata message
    ) external virtual override {
        // ...
    }
}

onCall receives:

• message: value of the payload
• amount: amount of deposited tokens
• zrc20: ZRC-20 address of a the deposited tokens (for example, contract address of ZRC-20 ETH)
• context:
  • context.origin: the original sender address on a connected chain (the EOA or contract that called the Gateway)
  • context.chainID: chain ID of the connected chain from which the call was made

When calling a universal app, the payload contains bytes passed to onCall as message. You don't need to pass a function selector in the payload as the only function that can be called from a connected chain is onCall.

Deposit ERC-20 Tokens and Call a Universal App

depositAndCall can also be used to call a universal app contract and send ERC-20 tokens.

depositAndCall(address receiver, uint256 amount, address asset, bytes calldata payload, RevertOptions calldata revertOptions) external;

The amount is the amount and asset is the token address of the ERC-20 that is being deposited.

In the current version of the protocol only one ERC-20 asset can be deposited at a time.

Call a Universal App

To call a universal app (without depositing tokens), use the call function.

call(address receiver, bytes calldata payload, RevertOptions calldata revertOptions) external;

Revert Transactions

For information on RevertOptions refer to the ZetaChain "Revert Transactions" doc.