Google Summer of Code / 2021

cronet.dart

Chromium networking.
A Dart interface.

A proof of concept for an HTTP client for Dart and Flutter built on Chromium’s networking stack. I developed it during Google Summer of Code 2021, mentored by Google’s Dart and Chromium teams.

Context: Google Summer of Code 2021
Stack: Dart, C, C++, dart:ffi
Platforms: Android, Linux, Windows, macOS
Status: Proof of concept · succeeded by cronet_http

01 / The idea

A native network stack, without leaving Dart.

Cronet is Chromium’s networking library. This project made its native C API accessible from Dart through dart:ffi, with an interface shaped like dart:io’s HttpClient.

The goal was to let Dart and Flutter applications use the networking stack underneath Chromium while keeping request and response handling familiar.

02 / Under the hood

Across the native boundary.

ApplicationDart / FlutterHttpClient-style API

Native bindingsdart:ffiC API boundary

Network stackChromium CronetNative HTTP networking

A Dart-facing client backed by Cronet’s native C API.

03 / The interface

Familiar at the call site.

A request to the first website ever made, sent through Chromium’s network stack.

import 'dart:convert';
import 'package:cronet/cronet.dart';

final client = HttpClient();
final request = await client.getUrl(
  Uri.parse('http://info.cern.ch/'),
);
final response = await request.close();
response.transform(utf8.decoder).listen(print);

Historical example for the original cronet package.

04 / Outcome & context

From GSoC to an open-source package.

The project was published under Google’s GitHub organisation and on pub.dev. In the project’s highly parallel workloads, it ran up to twice as fast as dart:io; that result is specific to those workloads.

Following my GSoC proof of concept, Google built the official successor, cronet_http. This page documents my original 2021 work; the successor package is the place to start for current use.