An Atomic Mechanism to Allow Publisher Contract Push Data to Subscriber Contracts
Abstract
This ERC proposes a push-based mechanism for sending data, allowing publisher contract to automatically push certain data to subscriber contracts during a call. The specific implementation relies on two interfaces: one for publisher contract to push data, and another for the subscriber contract to receive data. When the publisher contract is called, it checks if the called function corresponds to subscriber addresses. If it does, the publisher contract push data to the subscriber contracts.
Motivation
Currently, there are many keepers rely on off-chain data or seperate data collection process to monitor the events on chain. This proposal aims to establish a system where the publisher contract can atomicly push data to inform subscriber contracts about the updates. The direct on-chain interaction bewteen the publisher and the subscriber allows the system to be more trustless and efficient.
This proposal will offer significant advantages across a range of applications, such as enabling the boundless and permissionless expansion of DeFi, as well as enhancing DAO governance, among others.
Lending Protocol
An example of publisher contract could be an oracle, which can automatically push the price update through initiating a call to the subscriber protocol. The lending protocol, as the subscriber, can automatically liquidate the lending positions based on the received price.
Automatic Payment
A service provider can use a smart contract as a publisher contract, so that when a user call this contract, it can push the information to the subsriber contracts, such as, the users’ wallets like NFT bound accounts that follows ERC-6551 or other smart contract wallets. The user’s smart contract wallet can thus perform corresponding payment operations automatically. Compared to traditional approve needed approach, this solution allows more complex logic in implementation, such as limited payment, etc.
PoS Without Transferring Assets
For some staking scenarios, especially NFT staking, the PoS contract can be set as the subscriber and the NFT contracts can be set as the publisher. Staking can thus achieved through contracts interation, allowing users to earn staking rewards without transferring assets.
When operations like transfer of NFT occur, the NFT contract can push this information to the PoS contract, which can then perform unstaking or other functions.
DAO Voting
The DAO governance contract as a publisher could automatically triggers the push mechanism after the vote is completed, calling relevant subscriber contracts to directly implement the voting results, such as injecting funds into a certain account or pool.
A Graph Visualization of the Structure
+---------+ +-----------+ +-------------+
| Client | | Publisher | | Subscriber |
+---------+ +-----------+ +-------------+
| | |
| Call somefunc(...) | |
|------------------------->| |
| | |
| | Query Subscriber |
| |----------------- |
| | | |
| |<---------------- |
| | |
| | Call exec(bytes4 selector, bytes calldata data) |
| |------------------------------------------------------->|
| | |
| | Result |
| |<-------------------------------------------------------|
| | |
| Result | |
|<-------------------------| |
| | |