RPC Peering

RPC Peering is a user-centric app interoperation protocol.

It allows an app (the initiator) to request a user to connect it to another app (the responder) that supports the required RPC interface.

For example:

• A Web3 app can request the user to connect it to a Wallet app that supports the Ethereum JSON-RPC API interface.
• A note taking app can request to connect to an LLM that supports the Ollama HTTP API interface.
• An AI chat bot app can request to connect to some upstream app that supports a certain GRPC API interface.

How It Works

Let's assume the initiator app is a crypto portfolio tracker and it wants to connect to a responder app that supports the Ethereum JSON-RPC API.

1. The initiator app creates a Peering URI with the topic ethereum and its peering server URL.

import { PeeringURI } from 'rpcpeering';

// Create a peering URI that will tell the responder app to connect to the initiator's peering server
const peeringUri = new PeeringURI(
  'https://portfolio-tracker.example.com/rpcpeering', // The URL of the initiator's peering server
  'ethereum', // The topic the responder app must support
);
// The peering URI string is:
// `rpcpeering+ethereum:${encodeURIComponent('https://portfolio-tracker.example.com/rpcpeering')}`

// Display the peering URI to the user in a QR code so they can scan it with their waller app

2. The user scans the QR code with their wallet app, which opens the peering URI in the responder wallet app. The wallet app sends a session proposal to the initiator's peering server. It includes the URL of the responder's Ethereum JSON-RPC API and an advertisement of other topics its peering server supports.

POST /rpcpeering HTTP/1.1
Host: portfolio-tracker.example.com
Content-Type: application/json

{
  "url": "https://wallet.example.com/rpcpeering/ethereum",
  "advertise": ["ethereum", "solana"],
}

3. The initiator's peering server evaluates the session proposal. If the proposal is accepted, the initiator sends a response containing its own session proposal, including the URL of the initiator's Ethereum callback API, where the responder can send callback requests, and an advertisement of other topics its peering server supports.

{
  "url": "https://portfolio-tracker.example.com/rpcpeering/ethereum",
  "advertise": ["ethereum", "solana"],
}

4. The initiator and responder can now send Ethereum JSON-RPC requests to each other over the URLs specified in their session proposals.

Here's an example of the initiator app sending a eth_getBlockByNumber request to the responder app:

POST /rpcpeering/ethereum HTTP/1.1
Host: wallet.example.com
Content-Type: application/json

{
  "method": "eth_getBlockByNumber",
  "params": ["0x1b", true],
}