GetAuthor - Polygon gRPC

Example code for the GetAuthor grpc method. Сomplete guide on how to use GetAuthor grpc in GetBlock.io Web3 documentation.

Returns the address of the validator that authored (produced and signed) a specific block. Bor uses secp256k1 signatures appended to the extraData header field to identify block authors — this method recovers the author from the signature. Used by Heimdall to verify that blocks were produced by the correct validator subset for the active span.

Request Parameters

Parameter	Type	Required	Description
number	string	Yes	Block reference — tag or hex block number

Request Example

grpcurl

grpcurl -H 'x-access-token: <ACCESS_TOKEN>' \
        -d '{"number": "latest"}' \
        shared.ap-southeast-1.getblock.io:443 \
        bor.BorApi/GetAuthor

JavaScript (Node.js)

import * as grpc from '@grpc/grpc-js';
import protoLoader from '@grpc/proto-loader';

const GRPC_TARGET = 'shared.ap-southeast-1.getblock.io:443';
const ACCESS_TOKEN = '<ACCESS-TOKEN>';
const PROTO_PATH = './protos/bor/bor.proto';

const packageDefinition = protoLoader.loadSync(PROTO_PATH, {
    keepCase: true,
    longs: String,
    enums: String,
    defaults: true,
    oneofs: true,
    includeDirs: ['./protos'],
});
const proto = grpc.loadPackageDefinition(packageDefinition);
const BorApiClient = proto.bor.BorApi;
const client = new BorApiClient(GRPC_TARGET, grpc.credentials.createSsl());

const metadata = new grpc.Metadata();
metadata.add('x-access-token', ACCESS_TOKEN);

const request = {
    "number": "latest"
};

client.GetAuthor(request, metadata, (err, response) => {
    if (err) {
        console.error('gRPC error:', err.code, err.message);
        return;
    }
    console.log(JSON.stringify(response, null, 2));
});

Python

import grpc
from google.protobuf.json_format import MessageToJson

from bor import bor_pb2, bor_pb2_grpc

GRPC_TARGET = "shared.ap-southeast-1.getblock.io:443"
ACCESS_TOKEN = "<ACCESS-TOKEN>"

credentials = grpc.ssl_channel_credentials()
channel = grpc.secure_channel(GRPC_TARGET, credentials)
stub = bor_pb2_grpc.BorApiStub(channel)

metadata = [("x-access-token", ACCESS_TOKEN)]

request = bor_pb2.GetAuthorRequest(
    number="latest",
)
response = stub.GetAuthor(request, metadata=metadata)

print(MessageToJson(response, indent=2))

Go

package main

import (
    "context"
    "crypto/tls"
    "encoding/json"
    "fmt"
    "log"
    "time"

    "google.golang.org/grpc"
    "google.golang.org/grpc/credentials"
    "google.golang.org/grpc/metadata"

    "github.com/0xPolygon/polyproto/bor"
)

func main() {
    target := "shared.ap-southeast-1.getblock.io:443"
    accessToken := "<ACCESS-TOKEN>"

    creds := credentials.NewTLS(&tls.Config{})
    conn, err := grpc.Dial(target, grpc.WithTransportCredentials(creds))
    if err != nil {
        log.Fatalf("dial: %v", err)
    }
    defer conn.Close()

    client := bor.NewBorApiClient(conn)

    ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()
    ctx = metadata.AppendToOutgoingContext(ctx, "x-access-token", accessToken)

    req := &bor.GetAuthorRequest{
        Number: "latest",
    }
    resp, err := client.GetAuthor(ctx, req)
    if err != nil {
        log.Fatalf("rpc: %v", err)
    }

    j, _ := json.MarshalIndent(resp, "", "  ")
    fmt.Println(string(j))
}

Response Example

{
  "author": {
    "Hi": {
      "Hi": "2718481128240167593",
      "Lo": "13848821177151473057"
    },
    "Lo": 1989474573
  }
}

H160 and H256 encoding. In JSON representations of protobuf messages, common.H160 (20-byte addresses) and common.H256 (32-byte hashes) are shown here as hex strings for readability. The actual JSON wire format from grpcurl or MessageToJson reflects the message structure defined in common/common.proto — typically a nested object encoding. Applications using the typed generated clients receive H160/H256 as strongly-typed message objects, not strings.

Response Fields

Field	Type	Description
author	H160	The block author (validator) address

Use Cases

• Validator dashboards showing block production distribution

• Detecting when blocks are produced by unauthorized validators (a Heimdall-side sanity check)

• Producer performance analytics

Error Handling

gRPC Status (Code)	Message	Cause
UNAUTHENTICATED (16)	missing or invalid x-access-token	Access token missing from x-access-token gRPC metadata or invalid
PERMISSION_DENIED (7)	access denied	Access token doesn't have permission for this method or endpoint
INVALID_ARGUMENT (3)	invalid request	Request message is malformed or fails validation (e.g. invalid block number tag)
INTERNAL (13)	internal error	Server-side error while processing the request
UNAVAILABLE (14)	service unavailable	Bor node is temporarily unavailable (syncing, restart, or overload)
DEADLINE_EXCEEDED (4)	deadline exceeded	Request took longer than the client-configured timeout
RESOURCE_EXHAUSTED (8)	rate limit exceeded	Rate limit exceeded for your plan
NOT_FOUND (5)	block not found	Block number is beyond the current chain tip
INVALID_ARGUMENT (3)	malformed block reference	Block reference is not a valid tag or hex number

SDK Integration

TypeScript (ts-proto)

// 1. Vendor polyproto and generate typed clients with ts-proto:
//    git clone https://github.com/0xPolygon/polyproto
//    npx protoc \
//      --plugin=./node_modules/.bin/protoc-gen-ts_proto \
//      --ts_proto_out=./src/generated \
//      --ts_proto_opt=outputServices=grpc-js \
//      -I ./polyproto \
//      polyproto/bor/bor.proto polyproto/common/common.proto
//
// 2. Use the generated typed client:

import * as grpc from '@grpc/grpc-js';
import { BorApiClient } from './generated/bor/bor';

const client = new BorApiClient('shared.ap-southeast-1.getblock.io:443', grpc.credentials.createSsl());
const metadata = new grpc.Metadata();
metadata.add('x-access-token', '<ACCESS-TOKEN>');

const request = {
    "number": "0x48f0e2a"
};
const response = await new Promise((resolve, reject) => {
    client.GetAuthor(request, metadata, (err, res) => err ? reject(err) : resolve(res));
});
console.log(response);

Rust (tonic)

// 1. Vendor polyproto and add tonic-build to build.rs:
//    tonic_build::configure()
//        .compile(&["polyproto/bor/bor.proto"], &["polyproto"])?;
//
// 2. Use the generated typed client:

use tonic::{transport::{Channel, ClientTlsConfig}, Request};

pub mod bor {
    tonic::include_proto!("bor");
}
use bor::bor_api_client::BorApiClient;
use bor::GetAuthorRequest;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let tls = ClientTlsConfig::new();
    let channel = Channel::from_static("https://shared.ap-southeast-1.getblock.io")
        .tls_config(tls)?
        .connect()
        .await?;

    let mut client = BorApiClient::with_interceptor(channel, |mut req: Request<()>| {
        req.metadata_mut().insert(
            "x-access-token",
            "<ACCESS-TOKEN>".parse().unwrap(),
        );
        Ok(req)
    });

    let request = tonic::Request::new(GetAuthorRequest { /* fields */ });
    let response = client.get_author(request).await?;
    println!("{:?}", response);
    Ok(())
}