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Custom Contract Development

For more complex dApps requiring custom logic, you can integrate Mailbox contracts directly into your own contracts:

Import and use Mailbox smart contracts pseudocode​

import "Compose/Mailbox.sol";

contract CustomCrossChainDApp {
    Mailbox public mailbox;
    
    function sendMessage(uint256 destinationChain, address targetContract, 
                        string memory messageType, bytes memory data) {
        mailbox.write(destinationChain, targetContract, messageType, data);
    }
    
    function readMessage(uint256 sourceChain, address sourceContract, 
                        string memory messageType) returns (bytes memory) {
        return mailbox.read(sourceChain, sourceContract, messageType);
    }
}

Reading and Writing Messages​

The Mailbox contract provides simple read/write interfaces for cross-chain communication:

  • write(uint256 chainId, address contract, string messageType, bytes data) - Send message
  • read(uint256 chainId, address contract, string messageType) - Read message

This approach gives you full control over cross-chain logic while maintaining atomicity guarantees.