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WebSocket API

WebSocket APIs provide real-time subscriptions to blockchain events.

Endpoints​

CometBFT WebSocket​

NetworkURL
Sprintnetwss://rpc.sprintnet.monolythium.com:26657/websocket
Testnetwss://rpc.testnet.monolythium.com:26657/websocket
Mainnetwss://rpc.monolythium.com:26657/websocket

EVM WebSocket​

NetworkURL
Sprintnetwss://rpc.sprintnet.monolythium.com:8546
Testnetwss://rpc.testnet.monolythium.com:8546
Mainnetwss://rpc.monolythium.com:8546

CometBFT Subscriptions​

Subscribe to Events​

{
  "jsonrpc": "2.0",
  "method": "subscribe",
  "params": {
    "query": "tm.event='NewBlock'"
  },
  "id": 1
}

Event Types​

EventQuery
New blocktm.event='NewBlock'
New block headertm.event='NewBlockHeader'
Transactiontm.event='Tx'
Validator set updatestm.event='ValidatorSetUpdates'

Filtered Subscriptions​

{
  "jsonrpc": "2.0",
  "method": "subscribe",
  "params": {
    "query": "tm.event='Tx' AND transfer.sender='mono1abc...'"
  },
  "id": 1
}

Unsubscribe​

{
  "jsonrpc": "2.0",
  "method": "unsubscribe",
  "params": {
    "query": "tm.event='NewBlock'"
  },
  "id": 1
}

EVM Subscriptions​

Subscribe to New Heads​

{
  "jsonrpc": "2.0",
  "method": "eth_subscribe",
  "params": ["newHeads"],
  "id": 1
}

Response on each new block:

{
  "jsonrpc": "2.0",
  "method": "eth_subscription",
  "params": {
    "subscription": "0x...",
    "result": {
      "number": "0x1b4",
      "hash": "0x...",
      "parentHash": "0x...",
      "timestamp": "0x..."
    }
  }
}

Subscribe to Logs​

{
  "jsonrpc": "2.0",
  "method": "eth_subscribe",
  "params": [
    "logs",
    {
      "address": "0x...",
      "topics": ["0x..."]
    }
  ],
  "id": 1
}

Subscribe to Pending Transactions​

{
  "jsonrpc": "2.0",
  "method": "eth_subscribe",
  "params": ["newPendingTransactions"],
  "id": 1
}

Unsubscribe​

{
  "jsonrpc": "2.0",
  "method": "eth_unsubscribe",
  "params": ["0x...subscription_id..."],
  "id": 1
}

JavaScript Examples​

CometBFT​

const WebSocket = require('ws');

const ws = new WebSocket('wss://rpc.sprintnet.monolythium.com:26657/websocket');

ws.on('open', () => {
  ws.send(JSON.stringify({
    jsonrpc: '2.0',
    method: 'subscribe',
    params: { query: "tm.event='NewBlock'" },
    id: 1
  }));
});

ws.on('message', (data) => {
  const msg = JSON.parse(data);
  console.log('New block:', msg);
});

EVM (ethers.js)​

const { ethers } = require('ethers');

const provider = new ethers.WebSocketProvider(
  'wss://rpc.sprintnet.monolythium.com:8546'
);

// New blocks
provider.on('block', (blockNumber) => {
  console.log('New block:', blockNumber);
});

// Contract events
const filter = {
  address: '0x...',
  topics: [ethers.id('Transfer(address,address,uint256)')]
};

provider.on(filter, (log) => {
  console.log('Transfer event:', log);
});

Connection Management​

Reconnection​

function connect() {
  const ws = new WebSocket('wss://...');

  ws.on('close', () => {
    console.log('Connection closed, reconnecting...');
    setTimeout(connect, 5000);
  });

  ws.on('error', (err) => {
    console.error('WebSocket error:', err);
    ws.close();
  });
}

Heartbeat​

setInterval(() => {
  if (ws.readyState === WebSocket.OPEN) {
    ws.ping();
  }
}, 30000);

Configuration​

Enable WebSocket in your node:

# config.toml (CometBFT)
[rpc]
laddr = "tcp://0.0.0.0:26657"

# app.toml (EVM)
[json-rpc]
ws-address = "0.0.0.0:8546"

Rate Limits​

Public endpoints may limit:

  • Connections per IP
  • Subscriptions per connection
  • Messages per second

For heavy usage, run your own node.