EVM <-> Cosmos General Message Passing Demo

Axelar supports pass general message from EVM chains to Cosmos chains. Axelar confirms the message from a EVM chain, and forward the message as memo field via ICS20 packet.

It currently supports two integration methods:

• Native chain: Axelar confirms and forward arbitrary payload to the destination cosmos chian. The receiver chain needs to add a middleware and implement a customize handler to decode and process the payload.
• CosmWasm: For chains who enabled wasm module, and installed general purpose ibc hook middleware, Axelar supports call a Cosmwasm contract from an EVM smart contract. The message sender can either encodes the payload in Axelar defined schema . Axelar confirms the payload and translates to wasm execute message.

This repo contains examples for both native and wasm integration.

• multi send is a native integration example, it sends token to multiple recipients from evm chain to a cosmos chain.
• swap and forward sends token and calls a CosmWasm swap contract on Osmosis

EVM

Developer needs to deploy a smart contract that calls Axelar gateway to send cross-chain message, and decode message upon receiving the payload from a remote chain.

MultiSend.sol is a sample contract.

deploy.js and interact.js are scripts to deploy and interact with the sample contract.

Cosmos Native Integration

A Cosmos chain can integrate cross chain message passing by adding an IBC middleware, and a handler that implements GeneralMessageHandler interface to decode the paylod. MultiSendHandler is a sample implementation.

MultiSend is a sample transaction that sends payload to an EVM chain.

Wasm Integration

The smart contract needs to encode the payload in the following format in order to call a wasm contract

 bytes memory argValue = abi.encode(arg1, arg2, arg3...)

 bytes memory payload = abi.encode(
    wasm contract method name,
    argument name list,
    argument type list,
    argValue bytes
)

Axelar also reserves source_chain and source_address keywords in wasm contract argument name. Axelar replaces with its canonical chain and sender info if the contract call contains these arguments.