Skip to main content

Trigger AppGateway from onchain

Trigger AppGateway from Onchain Contracts​

This approach enables onchain contracts to communicate directly with your AppGateway on EVMx. It allows contracts deployed on blockchains to send data to EVMx, update information, and initiate chain-abstracted actions.

This pattern is particularly valuable for applications that need to:

  • Maintain consistent state across multiple blockchains
  • React to onchain events by triggering actions on other chains
  • Create workflows that start on one chain and continue on others

To implement this functionality, you'll need to:

  1. Extend your onchain contract with SOCKET Protocol's PlugBase
  2. Configure your AppGateway to accept messages from your onchain contract
  3. Implement a function in your onchain contract that calls the AppGateway

↘ See a reference implementation of this functionality here.

Extending with PlugBase​

The PlugBase contract serves as the foundation for onchain-to-EVMx communication. By inheriting from this contract, your onchain contracts gain the ability to connect to the SOCKET infrastructure and communicate with your AppGateway.

Key functions provided by PlugBase:

  • _connectSocket: Establishes a connection to the SOCKET infrastructure
  • _disconnectSocket: Terminates the connection when no longer needed
  • _callAppGateway: Sends data to your AppGateway on EVMx

Inheriting from PlugBase is the first step in creating a secure communication channel between your onchain contract and the EVMx environment.

Approving an onchain contract to communicate with your AppGateway​

For security reasons, your AppGateway must explicitly authorize which onchain contracts can send it messages. This is done through the setValidPlug function, which marks a specific onchain contract as a valid communication source.

You can automate this approval in your AppGateway's initialize function:

bytes32 public yourContractId = _createContractId("your-onchain-contract");

function initialize(uint32 chainSlug_) public override {
    // Allow the onchain contract to communicate with this AppGateway
    setValidPlug(chainSlug_, yourContractId, true);
}

The setValidPlug function takes three parameters:

  • chainSlug_: The chain identifier where your onchain contract is deployed
  • yourContractId: A unique identifier for your onchain contract
  • true: Sets the contract as an authorized communication source

Triggering AppGateway from an onchain contract​

Once your onchain contract inherits from PlugBase and is approved by the AppGateway, you can implement a function to send data to the AppGateway:

function triggerAppGateway(YourDataType payload_) external returns (bytes32) {
    // Encode your data and send it to the AppGateway
    return _callAppGateway(abi.encode(payload_), bytes32(0));
}

Parameters for _callAppGateway:

  • First parameter: Your encoded data that will be sent to the AppGateway
  • Second parameter: Reserved for additional execution information (currently use bytes32(0))

The function returns a transaction identifier that can be used to track the chain-abstracted call.

info

See a reference implementation of this functionality here.