Problem Statement

• Parahain to Parachain communication currently relies on the relay chain for message passing. i.e The relay chain currently forms a bottleneck in parachain messaging. This is highly inefficient and relieving the relay chain of this burden will not only allow for higher Parachain messaging throughput, but also parachain better scalability with async backing on the horizon.

• HRMP (The current transport protocol), necessitates the intervention of governance to establish communication channels between related chains. While this ensures a certain level of security and verification, it also adds a layer of complexity and time consumption. We believe parachain interoperability should be the juridisction of the governance of the parachains involved, not the relay chain.

• For chains to effectively interoperate with each other they must be able to read the state of that counterparty chain. This approach to interoperability are currently open & unasnwered questions today in the ecosystem: Support custom storage proof from the relay-chain, META: Parachains Reading Storage of One Another

Solution

ISMP (Interoperable State Machine Protocol) is designed to improve and secure cross-chain communication and operations by facilitating "GET-like" and "POST-like" requests between all substrate based chains under the security of the Polkadot Relay chain. By leveraging state proofs, it relieves the relay chain of the burden of message passing, contributing significantly to the scalability of parachains. It’s GET-like request protocol facilitates for the first time in the ecosystem state reads of sibling parachains, as well as the relay chain, unlocking new kinds of applications.

Inspired by HTTP, aiming to become a similar standard for interoperability in the multi-chain environment. It's designed as a substrate-based pallet to ease integration with parachains and standalone chains, Following a successful w3f grant delivery for the preliminary functionally which enables Parachain interoperability.

You can find a link to ISMP repository here: https://github.com/polytope-labs/ismp-substrate.

Relevant discussion links:

• Polkadot Forum discussion
• Polkadot decoded devrel stream
• The Kusamarian Interview
• Polkadot interoperability keynote at ParisDotComm

Ecosystem Use Cases

With the ability to read each other's state comes a new wave of applications unlocked by the ISMP stack

• Parachain messaging independent of cumbersome HRMP channel proposals.
• Unopinionated messaging format for parachains.
• Liquid Staking derivatives based on relay chain stake (Acala, Bifrost)
• Multi asset transaction fee collection for Parachains using 30 day Twap prices from Hydradx.
• Request user’s Klit DID on the Klit Parachain from any chain.
• and many more

The proposal

We have fully extended ISMP to facilitate messaging between; Standalone(solo) chains, Parachains & Relay chains. It is fully EVM compatible, enabling cross chain solidity smart contract communication among other ISMP-enabled EVM compatible (substrate based) chains. This messaging is powered by an offchain relayer implementation, engineered to be chain-agnostic and extensible to multiple ecosystems.

This proposal is for a retroactive payment by Polkadot Treasury to cover development costs incurred. This funding will allow us continue further research and development for our next major milestones, a zk bridge to ethereum that turns polkadot into a message passing platform for it's rollups.

You can find the details of the proposal here.

We look forward to your support.

Thank you for reading!