socket.io-client-dart

Port of awesome JavaScript Node.js library - Socket.io-client v2.0.1~v3.0.3 - in Dart

Version info:

socket.io-client-dart	Socket.io Server
v0.9.* ~ v1.*	v2.*
v2.*	v3.* & v4.*

Usage

Dart Server

import 'package:socket_io/socket_io.dart';

main() {
  // Dart server
  var io = Server();
  var nsp = io.of('/some');
  nsp.on('connection', (client) {
    print('connection /some');
    client.on('msg', (data) {
      print('data from /some => $data');
      client.emit('fromServer', "ok 2");
    });
  });
  io.on('connection', (client) {
    print('connection default namespace');
    client.on('msg', (data) {
      print('data from default => $data');
      client.emit('fromServer', "ok");
    });
  });
  io.listen(3000);
}

Dart Client

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

main() {
  // Dart client
  IO.Socket socket = IO.io('http://localhost:3000');
  socket.onConnect((_) {
    print('connect');
    socket.emit('msg', 'test');
  });
  socket.on('event', (data) => print(data));
  socket.onDisconnect((_) => print('disconnect'));
  socket.on('fromServer', (_) => print(_));
}

Connect manually

To connect the socket manually, set the option autoConnect: false and call .connect().

For example,

Socket socket = io('http://localhost:3000', 
    OptionBuilder()
      .setTransports(['websocket']) // for Flutter or Dart VM
      .disableAutoConnect()  // disable auto-connection
      .setExtraHeaders({'foo': 'bar'}) // optional
      .build()
  );
socket.connect();

Note that .connect() should not be called if autoConnect: true (by default, it's enabled to true), as this will cause all event handlers to get registered/fired twice. See Issue #33.

Update the extra headers

Socket socket = ... // Create socket.
socket.io.options['extraHeaders'] = {'foo': 'bar'}; // Update the extra headers.
socket.io..disconnect()..connect(); // Reconnect the socket manually.

Emit with acknowledgement

Socket socket = ... // Create socket.
socket.onConnect((_) {
    print('connect');
    socket.emitWithAck('msg', 'init', ack: (data) {
        print('ack $data') ;
        if (data != null) {
          print('from server $data');
        } else {
          print("Null") ;
        }
    });
});

Socket connection events

These events can be listened on.

const List EVENTS = [
  'connect',
  'connect_error',
  'connect_timeout',
  'connecting',
  'disconnect',
  'error',
  'reconnect',
  'reconnect_attempt',
  'reconnect_failed',
  'reconnect_error',
  'reconnecting',
  'ping',
  'pong'
];

// Replace 'onConnect' with any of the above events.
socket.onConnect((_) {
    print('connect');
});

Acknowledge with the socket server that an event has been received.

socket.on('eventName', (data) {
    final dataList = data as List;
    final ack = dataList.last as Function;
    ack(null);
});

Usage (Flutter)

In Flutter env. not (Flutter Web env.) it only works with dart:io websocket, not with dart:html websocket or Ajax (XHR), so in this case you have to add setTransports(['websocket']) when creates the socket instance.

For example,

IO.Socket socket = IO.io('http://localhost:3000',
  OptionBuilder()
      .setTransports(['websocket']) // for Flutter or Dart VM
      .setExtraHeaders({'foo': 'bar'}) // optional
      .build());

Usage with stream and streambuilder in Flutter

import 'dart:async';


// STEP1:  Stream setup
class StreamSocket{
  final _socketResponse= StreamController<String>();

  void Function(String) get addResponse => _socketResponse.sink.add;

  Stream<String> get getResponse => _socketResponse.stream;

  void dispose(){
    _socketResponse.close();
  }
}

StreamSocket streamSocket =StreamSocket();

//STEP2: Add this function in main function in main.dart file and add incoming data to the stream
void connectAndListen(){
  IO.Socket socket = IO.io('http://localhost:3000',
      OptionBuilder()
       .setTransports(['websocket']).build());

    socket.onConnect((_) {
     print('connect');
     socket.emit('msg', 'test');
    });

    //When an event recieved from server, data is added to the stream
    socket.on('event', (data) => streamSocket.addResponse);
    socket.onDisconnect((_) => print('disconnect'));

}

//Step3: Build widgets with streambuilder

class BuildWithSocketStream extends StatelessWidget {
  const BuildWithSocketStream({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: StreamBuilder(
        stream: streamSocket.getResponse ,
        builder: (BuildContext context, AsyncSnapshot<String> snapshot){
          return Container(
            child: snapshot.data,
          );
        },
      ),
    );
  }
}

Troubleshooting

Cannot connect "https" server or self-signed certificate server

• Refer to dart-lang/sdk#34284 issue. The workround is to use the following code provided by @lehno on #84

class MyHttpOverrides extends HttpOverrides {
  @override
  HttpClient createHttpClient(SecurityContext? context) {
    return super.createHttpClient(context)
      ..badCertificateCallback =
          (X509Certificate cert, String host, int port) => true;
  }
}

void main() {
  HttpOverrides.global = MyHttpOverrides();
  runApp(MyApp());
}

Memory leak issues in iOS when closing socket.

• Refer to rikulo#108 issue. Please use socket.dispose() instead of socket.close() or socket.disconnect() to solve the memory leak issue on iOS.

Connect_error on MacOS with SocketException: Connection failed

• Refer to flutter/flutter#47606 (comment) issue.

By adding the following key into the to file *.entitlements under directory macos/Runner/

<key>com.apple.security.network.client</key>
<true/>

For more details, please take a look at https://flutter.dev/desktop#setting-up-entitlements

Can't connect socket server on Flutter with Insecure HTTP connection

• Refer to https://flutter.dev/docs/release/breaking-changes/network-policy-ios-android

The HTTP connections are disabled by default on iOS and Android, so here is a workaround to this issue, which mentioned on stack overflow

Notes to Contributors

Fork socket.io-client-dart

If you'd like to contribute back to the core, you can fork this repository and send us a pull request, when it is ready.

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

Who Uses

• Quire - a simple, collaborative, multi-level task management tool.
• KEIKAI - a web spreadsheet for Big Data.

Socket.io Dart Server

• socket.io-dart

Contributors

• Thanks @felangel for rikulo#7
• Thanks @Oskang09 for rikulo#21
• Thanks @bruce3x for rikulo#25
• Thanks @Kavantix for rikulo#26
• Thanks @luandnguyen for rikulo#59
• Thanks @jorgefspereira for rikulo#177
• Thanks @fzyzcjy for rikulo#188
• Thanks @darwin-morocho for rikulo#189
• Thanks @chatziko for rikulo#237
• Thanks @Astray-git for rikulo#313
• Thanks @Astray-git for rikulo#310