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Socket.IO stream

Build Status NPM version

This is the module for bidirectional binary data transfer with Stream 2 API through Socket.IO.


$ npm install


For streaming between servers and clients, you must send stream instances first. To receive streams, you just wrap socket with, then listen any events as usual.


var io = require('').listen(80);
var ss = require('');
var path = require('path');

io.of('/user').on('connection', function(socket) {
  ss(socket).on('profile-image', function(stream, data) {
    var filename = path.basename(;

createStream() will return a new stream which can be sent by emit.


var io = require('');
var ss = require('');

var socket = io.connect('');
var stream = ss.createStream();
var filename = 'profile.jpg';

ss(socket).emit('profile-image', stream, {name: filename});

You can stream data from a client to server, and vice versa.


This module can be used on the browser. To do so, just copy a file to a public directory.

$ cp node_modules/ somewhere/public/

You can also use browserify to build manually.

$ npm install browserify -g
$ cd node_modules/
$ browserify index.js -s ss >
<input id="file" type="file" />

<script src="/"></script>
<script src="/js/"></script>
<script src="/js/jquery.js"></script>
$(function() {
  var socket = io.connect('/foo');

  $('#file').change(function(e) {
    var file =[0];
    var stream = ss.createStream();

    // upload a file to the server.
    ss(socket).emit('file', stream, {size: file.size});

Upload progress

You can track upload progress like the following:

var blobStream = ss.createBlobReadStream(file);
var size = 0;

blobStream.on('data', function(chunk) {
  size += chunk.length;
  console.log(Math.floor(size / file.size * 100) + '%');
  // e.g. '42%'




Look up an existing Socket instance based on sio (a socket of Socket.IO), or create one if it doesn't exist.

socket.emit(event, ...)

Emit an event with variable args including at least a stream.

socket.on(event, [options], [listener])

Add a listener for event. listener will take streams with any data as arguments. options is an object for streams.


Create a new duplex stream. See the docs for the details of stream and options.

ss.createBlobReadStream(blob, [options])

Create a new readable stream for Blob and File. See the docs for the details of stream and options.



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