Signaler

Manage webRTC connections without knowing how they work (more or less...).

This library exposes webRTC capabilities masquerading what has to be done for connecting peers to each other. As signaling server uses Comunicator.

The client could be used in AngularJS, via provider, or in plain javascript.

Signaler is developed by 720kb.

Requirements

This implementation needs a browser that has:

• webRTC implementation or objectRTC implementation (using the library that exposes webRTC methods using ORTC);
• the Comunicator requirements.

The AngularJS provider needs at least AngularJS version 1.2.

Installation

Signaler could be installed via npm or bower

NPM

$ npm install --save siglr

Bower

$ bower install --save signaler

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Node.js side

In node.js you have to instantiate Signaler passing a salt as showed here:

var jwtSalt = '_super_secret_salt_12345';
 
require('siglr')(jwtSalt);

The salt is used in conjunction with jwt to sign messages, achieving integrity in what is sent.

By default the websocket used as signaling channel is bound on 0.0.0.0:9876 address, but it can be configured setting COMUNICATOR_HOST and COMUNICATOR_PORT to the preferred host and port.

For example:

• COMUNICATOR_HOST='127.0.0.1';
• COMUNICATOR_PORT=7546:

That's all you have to do on the node.js side. The library will manage all practicable possible scenarios.

Client side

The files you need are:

• dist/signaler.min.js from this module and dist/comunicator.min.js from the Comunicator module for the plain javascript implementation;

• dist/signaler-angular.min.js from this module and dist/comunicator-angular.min.js from the Comunicator module for the AngularJS implementation.

If you are about to use the AngularJS provider you have to include the module that brings the provider, for example:

angular.module('app', [
  '720kb.signaler'
 ]);

API

Plain javascript

Signaler is a window object. To use it you need to create an instance of it, for example:

  var signaler = new window.Signaler(<backend comunicator url>, <media constraint object>, <sdp constraint object>);

The second and third parameters are respectively media constraints object and RTC offer/answer option object. They have default values that perform audio/video stream.

The instantiated object returns a Promise that is resolved when the client websocket is correctly connected to the websocket server.

The resolved object has the property myStream: this is the stream associated to the client.

Methods

The resolved object exposes also these methods:

• userIsPresent(whoami, token): this sends to signaling server who the client is and which jwt token will be used (it's a delegate of comunicator client userIsPresent() method);

• createChannel(channel): this sends a request to signaler server to create the channel channel;

• joinChannel(channel): this sends a request to signaler server to join the channel channel.

• leaveChannel(channel, keepMyStream): this disconnects the signaler client from channel. If you want to keep the stream retrieved by getUserMedia() you have to pass a truthy value to keepMyStream;

Clients that are connected each other now can send data via a Data Channel, this is possible calling the methods:

• sendTo(channel, who, what): this sends what to who in channel;

• broadcast(channel, what): this sends what to everyone in channel.

If you want to establish an audio/video stream (specified by the previous defined constraints), first you have to get the client stream calling:

• getUserMedia(): this wraps the getUserMedia() using the settings previously defined. Accepting the stream generates an window event that permits to continue the audio/video stream establishment procedure.

When the stream is retrieved, the client can send it calling the:

• streamOnChannel(channel, who): this sends the client stream in channel.

If the client is the one who calls createChannel() then the stream is sent to everyone who is connected in channel; this is the default behaviour that can be altered specifying the who parameter. The result is that the stream will be sent only to who. On the other hand, if the client who calls streamOnChannel() is the one who calls joinChannel(), the stream will be always sent to the channel creator. who parameter is ignored in this scenario.

The channel creator can administrate the joined users stream with the methods:

• approve(channel, whoToApprove): this approves the whoToApprove stream in channel. The result is that the stream reaches everyone in channel;

• unApprove(channel, whoToUnApprove): this unapproves the whoToUnApprove stream in channel. The result is that the whoToUnApprove stream will be removed to everyone in channel (excluding the channel creator).

Signaler client dispatches also events from window.

They are:

• signaler:error: dispatched when the handshake protocol finishes in an error state. The event payload contains the cause of the error as follows:

  {
    'detail': <error>
  }

• signaler:usermedia-error: dispatched when the user blocks the getUserMedia() revoking permission. The event payload contains the cause of the error as follows:

  {
    'detail': <error>
  }

• signaler:data-arrived: dispatched when a message arrives from data channel. The informations about message are in the payload:

  {
    'detail': {
      'payload': <message>,
      'whoami': <sender>,
      'channel': <channel>
    }
  }

• signaler:datachannel-opened: dispatched when a data channel is opened. The informations about the opened channel are in the event payload:

  {
    'detail': {
      'whoami': <client connected>,
      'channel': <channel>
    }
  }

• signaler:datachannel-closed: dispatched when a data channel is closed. The informations about the closed channel are in the event payload:

  {
    'detail': {
      'whoami': <client gone>,
      'channel': <channel>
    }
  }

• signaler:ready: dispatched when the p2p connection between clients is completed. The event payload contains the informations about the connected client:

  {
    'detail': {
      'channel': <channel>,
      'whoami': <client connected>
    }
  }

• signaler:stream: dispatched when a stream arrives from a client. The stream informations are in the event payload:

  {
    'detail': {
      'userid': <client identifier>,
      'stream': <stream arrived>
    }
  }

• signaler:end: dispatched when a client stream is closed. The stream informations are in event payload:

  {
    'detail': {
      'userid': <client identifier>
    }
  }

• signaler:my-stream: dispatched when local stream is ready (from getUserMedia() call). The stream informations are in the event payload:

  {
    'detail': {
      'userid': <local client identifier>,
      'stream': <local stream>
    }
  }

AngularJS

The provider exposes the initSignaler(<backend comunicator url>, <media constraint object>, <sdp constraint object>) that must be called to instantiate and configure the Signaler service.

Done that, the same object described for plain javascript is exposed as an AngularJS service. The events signaler:error, signaler:usermedia-error, signaler:data-arrived, signaler:datachannel-opened, signaler:datachannel-closed, signaler:ready, signaler:stream, signaler:end and signaler:my-stream are emitted from $rootScope and can be used inside your AngularJS application.

Contributing

We will be very grateful if you help us making this project grow up. Feel free to contribute by forking, opening issues, pull requests etc.

License

The MIT License (MIT)

Copyright (c) 2014 Dario Andrei, Filippo Oretti

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.