Talkbox

A proof of concept in building browser-based telephony applications using functional programming languages. The back-end is implemented with Elixir, the front-end implemented with Elm.

Why?

To improve my knowledge of functional programming. To learn what types of problems are more/less difficult to solve in the telephony domain using functional languages vs. object oriented languages.

What does it do?

Make a call from the browser
Receive a call from another browser
Make a conference call
Receive a call from a telephone

Design

This project serves as an umbrella enclosing many smaller applications.

Goals

Small, loosely coupled components, each with a narrow set of responsibilities
Components that can be tested in isolation

Components

Each of these components is implemented as a child-project under the /apps directory. This was done to promote the abovementioned design goals.

UI Serves the single page web application. Translates websocket messages from the client into events. Provides an endpoint for other applications (i.e. router) to send websocket messages back to the client.
Callbacks Accepts webhook requests from Twilio. Responds back with TwiML instructions and/or publishes events to broadcast that call state in Twilio has changed.
Telephony Manages the core business logic for the system. Maintains its own version of the call state separate from Twilio.
Router Handlers for events. Runs a pool of consumer processes that pull events from the event queue and delegate to the telephony or ui applications.
Events Contains event definitions used to communicate between applications and facilitates publishing of events

Set up

Install dependencies
```
brew bundle
```

Set environment variables

export TWILIO_ACCOUNT_SID=<account sid>
export TWILIO_AUTH_TOKEN=<auth token>

Run the tests
```
mix test
```
Start the applications
```
iex -S mix phoenix.server
```

Open the application

open http://localhost:5000/?client_name=yourname

Proposed enhancements

Resilience to client crash (fetch state from server at load)
Resilience to server crash (fetch call state from Twilio at boot)
Rolling deploys (proposing Docker with Consul)

pdawczak/talkbox