Socket.IO stream

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

Installation

npm install @wwa/socket.io-stream

Usage

If you are not familiar with Stream API, be sure to check out the docs. I also recommend checking out the awesome Stream Handbook.

For streaming between server and client, you will send stream instances first. To receive streams, you just wrap socket with socket.io-stream, then listen any events as usual.

Server:

const io = require('socket.io').listen(80);
const ss = require('@wwa/socket.io-stream');
const path = require('path');

io.of('/user').on('connection', function(socket) {
  ss(socket).on('profile-image', function(stream, data) {
    const filename = path.basename(data.name);
    stream.pipe(fs.createWriteStream(filename));
  });
});

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

Client:

const io = require('socket.io-client');
const ss = require('@wwa/socket.io-stream');

const socket = io.connect('http://example.com/user');
const stream = ss.createStream();
const filename = 'profile.jpg';

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

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

// send data
ss(socket).on('file', function(stream) {
  fs.createReadStream('/path/to/file').pipe(stream);
});

// receive data
ss(socket).emit('file', stream);
stream.pipe(fs.createWriteStream('file.txt'));

Browser

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

cp node_modules/@wwa/socket.io-stream/socket.io-stream.js somewhere/public/

You can also use browserify to create your own bundle.

npm install browserify -g
cd node_modules/@wwa/socket.io-stream
browserify index.js -s ss -o socket.io-stream.js

<input id="file" type="file" />

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

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

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

Upload progress

You can track upload progress like the following:

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

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

blobStream.pipe(stream);

Socket.IO v0.9 support

You have to set forceBase64 option true when using the library with socket.io v0.9.x.

ss.forceBase64 = true;

Documentation

ss(sio)

• sio socket.io Socket A socket of Socket.IO, both for client and server
• return Socket

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, [arg1], [arg2], [...])

• event String The event name

Emit an event with variable number of arguments including at least a stream.

ss(socket).emit('myevent', stream, {name: 'thefilename'}, function() { ... });

// send some streams at a time.
ss(socket).emit('multiple-streams', stream1, stream2);

// as members of array or object.
ss(socket).emit('flexible', [stream1, { foo: stream2 }]);

// get streams through the ack callback
ss(socket).emit('ack', function(stream1, stream2) { ... });

socket.on(event, listener)

• event String The event name
• listener Function The event handler function

Add a listener for event. listener will take stream(s) with any data as arguments.

ss(socket).on('myevent', function(stream, data, callback) { ... });

// access stream options
ss(socket).on('foo', function(stream) {
  if (stream.options && stream.options.highWaterMark > 1024) {
    console.error('Too big highWaterMark.');
    return;
  }
});

ss.createStream([options])

• options Object
  • highWaterMark Number
  • encoding String
  • decodeStrings Boolean
  • objectMode Boolean
  • allowHalfOpen Boolean if true, then the stream won't automatically close when the other endpoint ends. Default to false.
• return Duplex Stream

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

const stream = ss.createStream();

// with options
const stream = ss.createStream({
  highWaterMark: 1024,
  objectMode: true,
  allowHalfOpen: true
});

ss.createBlobReadStream(blob, [options])

• options Object
  • highWaterMark Number
  • encoding String
  • objectMode Boolean
• return Readable Stream

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

const stream = ss.createBlobReadStream(new Blob([1, 2, 3]));

ss.Buffer

Node Buffer class to use on browser, which is exposed for convenience. On Node environment, you should just use normal Buffer.

const stream = ss.createStream();
stream.write(new ss.Buffer([0, 1, 2]));

License

MIT