Actioncable

Installation

- 1) Add the :actioncable dependency to your mix.exs file

defp deps() do
  [
    {:actioncable, "~> 0.1.0"}
  ]

Then, run mix deps.get in your shell to fetch the new dependencies.

- 2) Add this configuration in config/config.ex,

config :your_application_name, Your_application_name_Web.Endpoint,
  check_origin: false,
    http: [
      dispatch: [
        {:_, [
          {"/cable", SocketHandler, []},
          {:_, Phoenix.Endpoint.Cowboy2Handler, {Your_application_name_Web.Endpoint, []}}
        ]}
      ]
    ],
    subprotocols: ["actioncable-v1-json"]

It will redirect every url ending by "/cable" to Cowboy Websocket Handler. Other url will be redirect in your Endpoint as usual.

- 3) Create module : Your_application_name_Web.SocketHandler

defmodule SocketHandler do
  use Actioncable.SocketHandler

  def handle_client_message(message) do
    #Handle message from JS client the way you want it ;)
    IO.inspect message
  end

end

This module has to use Actioncable.SocketHandlerand implement handle_client_messagefunction.

- 4) Start a Redix connection named :redix_ac

(it will be used for storing websocket pid in corresponding channel.)

In your application.ex :

def start(_type, _args) do
  children = [
    %{
      id: Redix,
      start: {Redix, :start_link, ["redis://localhost:6379/15", [name: :redix_ac]]}
    }
  ]
end

Note: in this case, i'm using redis database number 15. If the server shut down brutally, you may want to clean the different channel. You can do the following (You have to be sure that your redis database -in this case the redis database 15- does not store any other data) :

def start(_type, _args) do
  children = [
    %{
      id: Redix,
      start: {Redix, :start_link, ["redis://localhost:6379/15", [name: :redix_ac]]}
    }
  ]
  opts = [strategy: :one_for_one, name: XXX.Supervisor]
  ret = XXX.start_link(children, opts)
  Redix.command!(:redix_ac, ["flushdb"])
  ret
end

It will clean redis database 15 at every start.

Usage

• Receive message : As seen above, every message will be transfered in this function : handle_client_message(message) (In SocketHandler module)

• Send message : use Actioncable.Channel.broadcast(channel, message)

  Example:

  iex> Actioncable.Channel("room_1", %{"action"=>"write", "args" => "hello"})

  iex> Actioncable.Channel("room_1", %{"action"=>"write"})

  Broadcast message to all subscriber from given channel.

Improvement

• Do not hesitate to perform pull request, this is a first version and there are a lot of things that need to be improved