slotSubscribe

The slotSubscribe method opens a stream that emits a notification each time the validator processes a new slot. Pair it with slotUnsubscribe to stop receiving notifications.

None

// 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":"slotSubscribe"}

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.onSlotChange((slotInfo) => {
  console.log('Slot update:', {
    slot: slotInfo.slot,
    parent: slotInfo.parent,
    root: slotInfo.root
  })
})
 
// To unsubscribe later:
// await connection.removeSlotChangeListener(subscriptionId)

// subscribe response
{"jsonrpc":"2.0","result":0,"id":1}
 
// notification
{
  "jsonrpc": "2.0",
  "method": "slotNotification",
  "params": {
    "result": {
      "parent": 75,
      "root": 42,
      "slot": 76
    },
    "subscription": 0
  }
}

Use slotUnsubscribe with the subscription id returned by slotSubscribe to cancel the stream.

subscription_id: number - The subscription id to cancel.

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

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

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

slotSubscribe

Parameters

Request

Result

Unsubscribe