Wizz

Demo App to showcase using Cowboy HTTP(S) and WebSockets in Elixir & Plug.

Change Log

• Refer to tag 1.1.x / branch cowboy-1.1.x for Cowboy 1 version.
• Updated to include configuring cowboy to use secure transport.
• Implemented secure transport for WebSockets and HTTP handler.
• Swapped WebSockex for Socket in order to ensure secure transport.
• Added Generic Server wrapper WebSocketClient around Socket.

Configuration

Set Transport Scheme

Edit config/config.exs and set scheme to :http or :https

config :wizz,
  scheme: :http | :https

Run Server

$ iex -S mix

Examples

HTTPS Endpoint

Ensure scheme is set to :https.

I followed http://ezgr.net/increasing-security-erlang-ssl-cowboy/ when selecting the secure transport options for cowboy.

Request /ping endpoint over https://:

$ curl https://localhost:1447/ping --cacert "./priv/ssl/cacert.crt"
pong

Secure WebSocket

Same as HTTP examples below, except with https:// in protocol in URI.

Note that it is also, it is possible it use Wizz.Client.start_link/0 which will automatically compute the websocket URI endpoint / port / scheme based on the server configuration.

HTTP Endpoint

$ curl http://localhost:1447/ping
pong

$ curl http://localhost:1447/other
¯\_(ツ)_/¯ 404

WebSocket

I have included a websocket client module to demonstrating connecting to the websocket endpoint: Wizz.Client.

Start Server with Console:

$ iex -S mix

Create a WebSocket connection (spawn a client process):

# Establish WebSocket Connection
{:ok, client} = Wizz.Client.start_link("http://localhost:1447/ws")

Debug Log showing SocketHandler process spawned:

00:00:00.000 pid=<0.324.0> module=Wizz.SocketHandler [debug] websocket_init :tcp, []

If we establish another connection:

{:ok, c} = Wizz.Client.start_link("http://localhost:1447/ws")

Another process is spawned to handle this connection:

00:00:00.157 pid=<0.289.0> module=Wizz.SocketHandler [debug] init []

Send ping:

Wizz.Client.send(c, {:text, "ping"})

Client Log: send ping message (expect pong):

00:00:00.624 pid=<0.295.0> module=WebSocketClient [debug] Sending text frame with payload: ping

Server Log: ping received, sending pong:

00:00:00.624 pid=<0.300.0> module=Wizz.SocketHandler [debug] received: ping; sending: pong

Client Log: received pong

00:00:00.626 pid=<0.295.0> module=Wizz.Client [debug] Received Message - Type: :text -- Message: "pong"

Send arbitrary message:

Wizz.Client.send(c, {:text, "wow!"})

Client Log: Sending "wow!"

00:00:00.547 pid=<0.295.0> module=Wizz.Client [debug] Sending text frame with payload: wow!

Server Log: received "wow!", no reply

00:00:00.548 pid=<0.300.0> module=Wizz.SocketHandler [debug] received: wow!