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XChain Messaging

Omni Core’s cross chain messaging layer enables developers to send function calls across chains using the Portal contract or the XApp framework.

OmniPortal​

The OmniPortal contracts are the backbone of Omni’s messaging layer, allowing developers to send and receive cross-chain function calls (xcall). These contracts are the endpoints for interacting with Omni’s cross chain messaging layer.

Key Functionality:​

Outbound Calls (xcall): Developers can trigger cross-chain function calls by interacting with the xcall method in the Portal contract.

Example:

omni.xcall(
    destChainId,  // Target chain ID
    conf,         // Confirmation level
    to,           // Destination contract address
    data,         // Encoded calldata
    gasLimit      // Gas limit for execution
);

Fee Calculation (feeFor):

Use the feeFor method to calculate the cost of a cross-chain call based on calldata size and gas requirements.

 uint256 fee = omni.feeFor(destChainId, data, gasLimit);

You can find the source code for OmniPortal here.

Building with XApp​

For developers looking to simplify cross-chain interactions, Omni provides the XApp contract, which handles the boilerplate logic for interacting with the Portal contracts.

Features include:

Pre-Built Utilities:

  • xcall: Simplifies sending cross-chain calls, automatically handles fee payments.
  • feeFor: Calculates the required fee for a call.
  • isXCall: Detects whether a function is being executed via an inbound cross-chain call.

Default Confirmation Level:

  • Don't worry about confirmation levels.

See more about XApp in the code base: XApp