eth_subscribe - Mantle

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 for specific events on the blockchain.

It requires a WebSocket connection. When an event occurs, the server pushes a notification to the client.

Parameters

Parameter

Type

Description

subscriptionType

string

Type of subscription ("newHeads", "logs", "newPendingTransactions")

filterObject

object

(optional) Filter options for logs subscription

Request (WebSocket)

import axios from 'axios';

// Note: eth_subscribe requires WebSocket, but here's the message format
const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "eth_subscribe",
    "params": ["newHeads"],
    "id": "getblock.io"
});

console.log('WebSocket message:', data);

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

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

ws.onmessage = (event) => {
    console.log('Received:', JSON.parse(event.data));
};

import websocket
import json

def on_message(ws, message):
    print(f"Received: {message}")

def on_open(ws):
    ws.send(json.dumps({
        "jsonrpc": "2.0",
        "method": "eth_subscribe",
        "params": ["newHeads"],
        "id": "getblock.io"
    }))

ws = websocket.WebSocketApp(
    "wss://go.getblock.io/<ACCESS-TOKEN>/",
    on_message=on_message,
    on_open=on_open
)
ws.run_forever()

// Note: eth_subscribe requires WebSocket connection
// Example message format for WebSocket client
let message = r#"{
    "jsonrpc": "2.0",
    "method": "eth_subscribe",
    "params": ["newHeads"],
    "id": "getblock.io"
}"#;

Subscription Types

Type

Description

newHeads

Fires when new block is added to chain

logs

Fires when logs matching filter are included

newPendingTransactions

Fires when new pending tx is added to pool

Response

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x9ce59a13059e417087c02d3236a0b1cc"
}

Notification Example (newHeads)

{
    "jsonrpc": "2.0",
    "method": "eth_subscription",
    "params": {
        "subscription": "0x9ce59a13059e417087c02d3236a0b1cc",
        "result": {
            "number": "0x3f6778",
            "hash": "0x9b14d73f45c836bfb0e1f59453c39fe8cddab45a0f78670dc6190e5c85b65a8e",
            "parentHash": "0x...",
            "timestamp": "0x..."
        }
    }
}

Response Parameters

Field

Type

Description

result

string

Subscription ID for managing the subscription

Use Case

The eth_subscribe method is essential for:

Real-time block monitoring
Event streaming
Live transaction tracking
DApp real-time updates
Notification systems

Error Handling

Status Code

Error Message

Cause

403

Forbidden

Missing or invalid ACCESS-TOKEN

-32000

Subscription not supported

HTTP used instead of WebSocket

Web3 Integration

import { ethers } from 'ethers';

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

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

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

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

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

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