rtc-bufferedchannel

This is a wrapper for a native RTCDataChannel that ensures that data sent over the channel complies with the current data channel size limits (which is < 16Kb for firefox <--> chrome interop).

NOTE: The rtc-bufferedchannel module is able to wrap any standard RTCDataChannel object. If you use other WebRTC helper libraries, then this module can still be very useful!

How it Works

The rtc-bufferedchannel works by wrapping a standard RTCDataChannel with an object that proxies send function calls and emits data through an channel.on('data', handler) event handler for receiving data. When you call the send function provided by buffered channel it determines the size of the message that you are sending and determines whether that needs to be "chunked" to assist with successful delivery of your data.

At this present point in time, a browser will complain if you attempt to send large payloads of data via a data channel, and this is where the rtc-bufferedchannel module comes to your rescue.

Typed Array Handling

Since rtc-bufferedchannel@0.3 all manner of typed integer arrays (int, uint, etc) are catered for and correctly chunked to ensure successful delivery. Additionally, the module will provide identification of the typed array type before sending the raw data across the wire. Using this functionality when you receive the data event from the buffered channel you will receive the data in the same format it was sent from your peer, i.e. Uint8Array in, Uint8Array out which is different to the standard data channel functionality.

Example Usage

Shown below is a simple example of how you might use a buffered channel to send data that is larger than what you can typically send over a webrtc data channel:

var quickconnect = require('rtc-quickconnect');
var buffered = require('rtc-bufferedchannel');
 
// include the base64 encoded image data
var mentosImage = require('../test/data/dietcoke-mentos');
 
quickconnect('http://rtc.io/switchboard', { room: 'buffertest' })
  .createDataChannel('mentos')
  .once('mentos:open', function(dc, id) {
    var bc = buffered(dc);
    console.log('found new peer (id = ' + id + '), sending an image');
 
    // when we get some data, then create a new image
    bc.on('data', function(data) {
      var img;
 
      console.log('received some image data', data);
      img = document.createElement('img');
      img.src = data;
 
      document.body.appendChild(img);
    });
 
    // send the mentos data to the person that just connected to us
    bc.send(mentosImage);
  });

License(s)

Apache 2.0

Copyright 2014 National ICT Australia Limited (NICTA)

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.