socket_io_plus 2.0.0+1

Port of JS/Node library Socket.io. It enables real-time, bidirectional and event-based communication cross-platform. Dart 3 compatible fork.

socket_io_plus

A Dart 3 compatible port of the Socket.IO server library.
Real-time, bidirectional, event-based communication — fully null-safe and ready for modern Dart.

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Features

• Full Dart 3 null-safety support
• WebSocket and XHR/JSONP polling transports
• Namespace (multiplexing) support
• Room-based broadcasting
• In-memory socket adapter
• Compatible with the official socket_io_client and JS Socket.IO clients

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Installation

Add to your pubspec.yaml:

dependencies:
  socket_io_plus: ^2.0.0

Then run:

dart pub get

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Quick Start

Server (Dart)

import 'package:socket_io_plus/socket_io.dart';

void main() async {
  final io = Server();

  // Default namespace
  io.on('connection', (Socket client) {
    print('Client connected: ${client.id}');

    client.on('msg', (data) {
      print('Message from client: $data');
      client.emit('fromServer', 'ok');
    });

    client.on('disconnect', (_) {
      print('Client disconnected: ${client.id}');
    });
  });

  // Custom namespace
  final nsp = io.of('/chat');
  nsp.on('connection', (Socket client) {
    print('Client connected to /chat');

    client.on('message', (data) {
      // Broadcast to everyone in the namespace
      nsp.emit('broadcastMessage', data);
    });
  });

  await io.listen(3000);
  print('Server running on port 3000');
}

Client — JavaScript

const socket = io('http://localhost:3000');

socket.on('connect', () => console.log('connected'));
socket.on('fromServer', (data) => console.log('from server:', data));
socket.on('disconnect', () => console.log('disconnected'));

socket.emit('msg', 'hello');

Client — Dart

import 'package:socket_io_client/socket_io_client.dart' as IO;

void main() {
  final socket = IO.io('http://localhost:3000');

  socket.on('connect', (_) {
    print('connected');
    socket.emit('msg', 'hello from Dart');
  });

  socket.on('fromServer', (data) => print('from server: $data'));
  socket.on('disconnect', (_) => print('disconnected'));
}

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Rooms

Sockets can join and leave named rooms. Broadcast to all members of a room:

io.on('connection', (Socket client) {
  client.join('room1');

  client.on('msg', (data) {
    // Emit to all sockets in 'room1'
    io.to('room1').emit('roomMessage', data);
  });
});

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Namespaces

Create separate communication channels that share the same underlying connection:

final admin = io.of('/admin');
admin.on('connection', (Socket client) {
  client.emit('welcome', 'You are in the admin namespace');
});

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Transports

Powered by Engine.IO, two transports are supported:

Transport	Description
polling	XHR / JSONP long-polling (HTTP fallback)
websocket	Full-duplex WebSocket connection

Clients start with polling and upgrade to WebSocket automatically when available.

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Migration from socket_io

This package is a Dart 3 compatible fork of socket_io. To migrate:

1. Replace socket_io with socket_io_plus in pubspec.yaml
2. Update all imports:

// Before
import 'package:socket_io/socket_io.dart';

// After
import 'package:socket_io_plus/socket_io.dart';

No other code changes are required.

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Dart Client Package

Use socket_io_client to connect a Dart client to this server.

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Contributing

Contributions are welcome! Please open an issue or submit a pull request.

If you are new to Git or GitHub, read this guide first.

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License

This project is licensed under the MIT License.