The rootSubscribe method opens a stream that emits a notification each time the validator sets a new root slot. The notification payload is a single number: the slot of the new root. Pair it with rootUnsubscribe to stop receiving notifications.

Parameters

• None

Request

// initiate websocket stream first
wscat -c wss://solana-mainnet.g.alchemy.com/v2/<-- ALCHEMY APP API KEY -->
 
// then call subscription
{"jsonrpc":"2.0","id":1,"method":"rootSubscribe"}

import { Connection } from '@solana/web3.js'
 
const connection = new Connection(
  'https://solana-mainnet.g.alchemy.com/v2/<-- ALCHEMY APP API KEY -->',
  {
    wsEndpoint: 'wss://solana-mainnet.g.alchemy.com/v2/<-- ALCHEMY APP API KEY -->'
  }
)
 
const subscriptionId = connection.onRootChange((rootSlot) => {
  console.log('New root slot:', rootSlot)
})
 
// To unsubscribe later:
// await connection.removeRootChangeListener(subscriptionId)

Result

// subscribe response
{"jsonrpc":"2.0","result":0,"id":1}
 
// notification
{
  "jsonrpc": "2.0",
  "method": "rootNotification",
  "params": {
    "result": 42,
    "subscription": 0
  }
}

Unsubscribe

Use rootUnsubscribe with the subscription id returned by rootSubscribe to cancel the stream.

• subscription_id: number - The subscription id to cancel.

{"jsonrpc":"2.0","id":1,"method":"rootUnsubscribe","params":[subscription_id]}

{"jsonrpc":"2.0","result":true,"id":1}

When using @solana/web3.js, call connection.removeRootChangeListener(subscriptionId) instead of sending the raw JSON-RPC request.