eth_subscribe - Somnia

Example code for the eth_subscribe JSON-RPC method. Complete guide on how to use eth_subscribe JSON-RPC in GetBlock Web3 documentation

This method creates a subscription over WebSocket on the Somnia network for real-time event notifications. Given Somnia's ~100ms block times and high throughput, subscriptions enable efficient real-time monitoring without polling. This method requires a WebSocket connection.

This method requires a WebSocket connection (not HTTP).

Parameters

Parameter

Type

Required

Description

subscriptionType

string

Yes

Type: "newHeads", "logs", "newPendingTransactions"

filterObject

object

Filter options (for "logs" type)

Subscription Types

newHeads - Subscribe to new block headers
logs - Subscribe to contract event logs
newPendingTransactions - Subscribe to pending transactions

Request Example

cURL (wscat)

# This method requires WebSocket connection
wscat -c wss://go.getblock.io/<ACCESS-TOKEN>/

> {"jsonrpc":"2.0","method":"eth_subscribe","params":["newheads"],"id":"getblock.io"}

JavaScript (ws)

const WebSocket = require('ws');

const ws = new WebSocket('wss://go.getblock.io/<ACCESS-TOKEN>/');

ws.on('open', () => {
    ws.send(JSON.stringify({
        jsonrpc: '2.0',
        method: 'eth_subscribe',
        params: ['newHeads'],
        id: 'getblock.io'
    }));
});

ws.on('message', (data) => {
    console.log(JSON.parse(data));
});

Python (websockets)

import asyncio
import websockets
import json

async def unsubscribe():
    uri = "wss://go.getblock.io/<ACCESS-TOKEN>/"
    async with websockets.connect(uri) as ws:
        payload = {
            "jsonrpc": "2.0",
            "method": "eth_subscribe",
            "params": ["newHeads"],
            "id": "getblock.io"
        }
        await ws.send(json.dumps(payload))
        response = await ws.recv()
        print(json.loads(response))

asyncio.run(unsubscribe())

Rust (tokio-tungstenite)

use tokio_tungstenite::connect_async;
use futures_util::{SinkExt, StreamExt};
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let url = "wss://go.getblock.io/<ACCESS-TOKEN>/";
    let (mut ws, _) = connect_async(url).await?;
    
    let payload = json!({
        "jsonrpc": "2.0",
        "method": "eth_subscribe",
        "params": ["newHeads"],
        "id": "getblock.io"
    });
    
    ws.send(payload.to_string().into()).await?;
    
    if let Some(msg) = ws.next().await {
        println!("{:?}", msg?);
    }
    
    Ok(())
}

Response Example

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x9cef478923ff08bf67fde6c64013158d"
}

{
  "jsonrpc": "2.0",
  "method": "eth_subscription",
  "params": {
    "subscription": "0x9cef478923ff08bf67fde6c64013158d",
    "result": {
      "number": "0x1a2b3c",
      "hash": "0x4e3a3754410177e6937ef1f84bba68ea139e8d1a2258c5f85db9f1cd715a1bdd",
      "parentHash": "0xb903239f8543d04b5dc1ba6579132b143087c68db1b2168786408fcbce568238",
      "timestamp": "0x65a1b2c3"
    }
  }
}

Response Parameters

Parameter

Type

Description

subscription

string

Subscription ID

result

object

Event data (varies by subscription type)

Use Cases

Real-time block monitoring
Live event tracking for dApps
Instant transaction notifications
Building live dashboards
MEV and arbitrage detection

Error Handling

Error Code

Description

-32602

Invalid subscription type or filter

-32603

Internal error

Connection closed

WebSocket disconnected

SDK Integration

ethers.js

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

const provider = new ethers.WebSocketProvider('wss://go.getblock.io/<ACCESS-TOKEN>/');

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

// Subscribe to contract events
const contract = new ethers.Contract(address, abi, provider);
contract.on('Transfer', (from, to, value) => {
  console.log('Transfer:', from, to, value);
});

viem.js

import { createPublicClient, webSocket } from 'viem';
import { somnia } from 'viem/chains';

const client = createPublicClient({
  chain: somnia,
  transport: webSocket('wss://go.getblock.io/<ACCESS-TOKEN>/')
});

const unwatch = client.watchBlocks({
  onBlock: (block) => console.log('New block:', block.number)
});

// Later: unwatch();

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