XCMP pallet calling with Kylin

Maarten Henskens
Astar Network
Published in
2 min readJul 31, 2021

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Polkadot’s Cross-chain Message Passing protocol, known as ‘XCMP’, is a game-changer and unique feature in the Polkadot ecosystem. XCMP allows consensus-based message passing between a parachain and another parachain.

The XCMP is no longer conceptual: in February of this year, we collaborated with Acala to undertake a token transfer between our native chains. This successful ‘XCMP-lite’ implementation, was just the first step. Now, the Kylin network is working with Astar to build on top of that work for the next evolution of the XCMP implementation and test out cross-chain calls for full functionality. In other words, calling a function that lives on another chain.

This is groundbreaking stuff! We are doing this XCMP using Chachacha build by Centrifuge with Kylen to call each others’ technology.

What has been done?

XCMP is normally a one-way message, essentially the chain sending an XCMP message cannot await a response. What we have done with Kylin is worked around that limitation by implementing a queuing system for requests. We then process those requests (from each parachain that requested it) in our Off-Chain worker and retrieve the requested data then send out the response. This is a much more efficient architecture because it is decentralized and essentially non-blocking, so the OCW call can take as long as it needs to and the parachains can just get on with producing blocks and receive the response when it’s are ready.

XCMP Architecture

Demo

Mario and Sam got together and did a demo and explained how this was achieved. A great achievement for the entire Polkadot ecosystem.

Demo

About Kylin Network

Kylin Network aims to build a cross-chain platform powering the data economy on Polkadot. It will be the data infrastructure for the future DeFi and Web 3.0 powered by Polkadot. Kylin Network will provide valid, reliable, secure, cost-effective, and easily coordinated data sources and data analytics.

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About Astar

Astar Network is a dApp hub on Polkadot that supports Ethereum, WebAssembly, and layer 2 solutions like ZK Rollups. Astar aims to be a multi-chain smart contract platform that will support multiple blockchains and virtual machines.

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