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SKALE Docs

Message Proxy

A message proxy within the SKALE Ecosystem is a key “connection” point that works to send and receive messages between Ethereum and SKALE Chains. MessageProxy is an abstract smart contract that is extended into two key smart contracts used as cornerstones of the SKALE IMA Messaging Layer:

  1. MessageProxyForMainnet — the MessageProxy deployed on the Ethereum Mainnet with an architecture designed for posting messages to SKALE Chains
  2. MessageProxyForSchain — the MessageProxy that is pre-deployed on every SKALE Chain that enables communication with Ethereum Mainnet AND communication SKALE Chain to SKALE Chain

MessageProxy is used to send messages to any contracts. It is used within the bridging layer to actually prepare and execute messages for transportation between between chains.

Architecture

Section titled “Architecture”
  • MessageProxy contracts are deployed on Mainnet, MessageProxyForMainnet, and each SKALE Chain, MessageProxyForSchain.
  • Contracts must be registered to a MessageProxy which allows them to interact with IMA Agent
  • Messages sent via MessageProxy are processed by the IMA Agent.
  • Messages received via MessageProxy are forwarded to the contract contract and executed

Basic Implementation

Section titled “Basic Implementation”

Utilize the following base flow to send a message:

interface IMessageProxy {
  function postOutgoingMessage(
    bytes32 targetChainHash,
    address targetContract,
    bytes calldata data
  ) external;
}


contract ExampleSendContract {


  IMessageProxy private messageProxy = IMessageProxy(0xd2AAa00100000000000000000000000000000000); // Use this address for sChain, otherwise use the proper Mainnet Address


  function sendMessageToMainnet(address targetContracts, bytes calldata data) external {
    messageProxy.postOutgoingMessage(keccak256(abi.encodePacked("Mainnet")), targetContract, data);
  }
}

Utilize the following base flow to receive a message:

contract ExampleReceiveContract {


  function postMessage(
      bytes32 schainHash,
      address sender,
      bytes calldata data
    )
      external
      returns (address)
  {
      [add in your processing logic]
  }
}

IMA Agent

Section titled “IMA Agent”

The IMA Agent is a service that runs within each SKALE Supernode that handles watching for transactions that are executed via MessageProxy* and processes them as messages accordingly. The agent automatically utilizes the nodes trusted execution environment (TEE) through Intel SGX© to handle the processing of messages.

Managing IMA

Section titled “Managing IMA”

IMA, similar to other predeployed contracts running on SKALE, is a highly customizable and managed by the SKALE Chain Owner/Operator or accounts delegated to them. The following are managed by the SKALE Chain Owner:

Message Size Limit

Section titled “Message Size Limit”

The default message size limit is 1,000,000 gas units. This limit can be changed on each individual SKALE Chain with the following process:

  1. Assign CONSTANT_SETTER_ROLE, an OpenZeppelin-based smart contract role, to one of your multisignature wallets or trusted delegated accounts. This call can be made by the SKALE Chain Owner or directly if another account is able to assign this role to your contract.
Terminal window
npx msig encodeData schain-name-here MessageProxyForSchain grantRole 0x96e3fc3be15159903e053027cff8a23f39a990e0194abcd8ac1cf1b355b8b93c [0x-wallet-address-of-executor]
  1. Once assigned, use your account to set the new gas limit.
Terminal window
npx msig encodeData schain-name-here MessageProxyForSchain setNewGasLimit 3000000