FreeClimb WebRTC Example

Example code and libraries to make a WebRTC enabled call through FreeClimb.

How To

To run the example contained in this repository:

1. Ensure you have created the .env file from the .env.example with your FreeClimb details
2. Install python dependencies with pip install -r requirements.txt
   • optionally utilize a python virtual environment
     • python3 -m venv venv
     • source venv/bin/activate
     • pip install -r requirements.txt
3. Run the server with FLASK_APP=main.py flask run --port 5001
   • this is a development server, not for production use
4. Connect to http://localhost:5001/webrtc-calls via Google Chrome browser, this demo application has only been tested in Google Chrome.
5. Click on the desired call button
6. Hangup (if desired)

SDK

The SDK, whistle-engine.js, provides primitives to interface with the JsSIP Library in a convenient fashion, allowing for easy registration of callbacks and a simplified interface.

Example usage of the whistle-engine.js SDK:

var config = {
    'user': '< FROM USER >',
    'domain': '< DOMAIN for USERS >',
    'proxy': '< SIP Gateway (often the same as domain) >',
    'port': 443,
    'authorization_jwt': `Bearer < JWT >`,

    // optional hooks to customize functionality
    'call_failed': function () {}
    'call_connected': function () {}
    'call_disconnected': function () {}
    'call_ended': function () {}
    'incoming_call': function () {}
};

engine = new WhistleEngine();
engine.start(config);
engine.dial("+1234567890");

FreeClimb WebRTC Flow

sequenceDiagram
    actor eu as End User
    participant s as Customer Server
    participant ls as FreeClimb API Server
    participant lssm as FreeClimb WebRTC Media Gateway
    participant lsss as FreeClimb WebRTC SIP Gateway
    eu ->> s: End User connects to customer server to access webpage (HTTPS)
    s ->> eu: Customer Server provides webpage (HTTPS)
    eu ->> s: End User requests WebRTC call (HTTPS)
    s ->> ls: Customer Server requests JWT from FreeClimb API Server (HTTPS)
    ls ->> s: FreeClimb API Server provides JWT (HTTPS)
    s ->> eu: JWT is provided to End User Browser (HTTPS)
    eu ->> lsss: JWT Used in SIP Request to SIP Gateway (WSS)
    lsss ->> eu: SIP negotiation occurs to determine RTP Media Gateway (WSS)
    loop Until Call Completes
    eu ->> lssm: RTP is streamed to/from Media Gateway (WebRTC)
    end

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Structure of Example Application

This repo contains several components used to generate necessary authentication credentials as well as host a simple website used for demonstrating a WebRTC call.

Object	Function
static	Both the underlying SIP library JsSIP as well as the SDK
templates	The sample HTML document that the Flask application renders with the requested config
main.py	This is the Python web application that will serve both the HTML document as well as interface with the FreeClimb API Server
requirements.txt	The list of required Python dependencies and versions, used for setup
.env.example	The example environment variables used to configure the Flask application
Dockerfile	The Dockerfile contains instructions for building the application as a Docker image as an alternate method of running