socket-io.md

The Socket.io Provider

The feathers-socketio provider adds support for Socket.io which enables real-time bi-directional, event-based communication. It works on every platform, browser or device, focusing equally on reliability and speed.

Server Side Usage

Install the provider module with:

$ npm install feathers-socketio

Then import the module and pass it to app.configure. The following example will start a server on port 3030 and also set up Socket.io:

const feathers = require('feathers');
const socketio = require('feathers-socketio');

const app = feathers().configure(socketio());

app.listen(3030);

Configuration

Once the server has been started with app.listen() the Socket.io object is available as app.io. It is also possible to pass a function that gets called with the initialized io server object (for more details see the Socket.io server documentation). This is a good place to listen to custom events or add authorization:

const feathers = require('feathers');
const socketio = require('feathers-socketio');

const app = feathers()
  .configure(socketio(function(io) {
    io.on('connection', function(socket) {
      socket.emit('news', { text: 'A client connected!' });
      socket.on('my other event', function (data) {
        console.log(data);
      });
    });
    
    // Registering Socket.io middleware
    io.use(function (socket, next) {
      // Exposing a request property to services and hooks
      socket.feathers.referrer = socket.request.referrer;
      next();
    });
  }));

app.listen(3030);

It is also possible to additionally pass a Socket.io options object. This can be used to e.g. configure the path where Socket.io is initialize (socket.io/ by default). The following changes the path to ws/:

const feathers = require('feathers');
const socketio = require('feathers-socketio');

const app = feathers()
  .configure(socketio({
    path: '/ws/'
  }, function(io) {
    // Do something here
    // This function is optional
  }));

app.listen(3030);

Middleware and service parameters

Similar to REST provider middleware, Socket.io middleware can modify the feathers property on the socket which will then be used as the service parameters:

app.configure(socketio(function(io) {
  io.use(function (socket, next) {
    socket.feathers.user = { name: 'David' };
    next();
  });
}));

app.use('messages', {
  create(data, params, callback) {
    // When called via SocketIO:
    params.provider // -> socketio
    params.user // -> { name: 'David' }
  }
});

Client Side Usage

A detailed description of the usage on a client can be found in Feathers Socket.io client chapter.