XMPP bot with Phoenix on Raspberry Pi

This is basically the recreation of this article “Hands on XMPP(MongooseIM) connection from Phoenix/Elixir using Hedwig” with latest version of Phoenix framework.

First, create new phoenix project with mix phx.new phxchat. It will also install dependencies.

Adjust config/dev.exs and create database by mix ecto.create .

Now, you can start phoenix with iex -S mix phx.server and check the page at http://localhost:4000

Add hedwig_xmpp as dependencies:

@@ -20,6 +20,7 @@ defmodule Phxchat.MixProject do
   def application do
     [
       mod: {Phxchat.Application, []},
+      application: [:hedwig_xmpp],
       extra_applications: [:logger, :runtime_tools]
     ]
   end
@@ -42,7 +43,8 @@ defmodule Phxchat.MixProject do
       {:phoenix_live_reload, "~> 1.2", only: :dev},
       {:gettext, "~> 0.11"},
       {:jason, "~> 1.0"},
-      {:plug_cowboy, "~> 2.0"}
+      {:plug_cowboy, "~> 2.0"},
+      {:romeo, git: "https://github.com/scrogson/romeo", override: true},
+      {:hedwig_xmpp, "~>1.0"}
     ]
   end

We also need the git version of romeo to avoid a bug on OTP 20. Run mix deps.get again to install dependencies.

Let’s create Phoenix channel for communication between browser and server first.

In lib/phxchat_web/channels/user_socket.ex, uncomment channel room

## Channels
channel "room:*", PhxchatWeb.RoomChannel

Also uncomment socket.js in assets/js/app.js

import socket from "./socket"

Create lib/phxchat_web/channels/room_channel.ex as

defmodule PhxchatWeb.RoomChannel do
  use Phoenix.Channel
  def join("room:lobby", auth_msg, socket) do
    {:ok, socket}
  end
end

Change the channel to “room:lobby” in assets/js/socket.js

let channel = socket.channel("room:lobby", {})

Now, check http://localhost:4000 again with web console opened. It would show ‘joined successfully’

To start using Hedwig, add this into config/config.exs

config :hedwig, Phxchat.Handlers.Echo,
    adapter: Hedwig.Adapters.XMPP,
    name: "hedwig",
    aka: "/",
    jid: "user@domain.com",
    password: "password",
    nickname: "user",
    rooms: [
      {"user@domain.com", []}
    ],
    handlers: [{Phxchat.Handlers.Echo, %{}}]

Create the echo handler at lib/handlers/echo_handler.ex

defmodule Phxchat.Handlers.Echo do
  use Hedwig.Robot, otp_app: :hedwig
  require Logger
  def handle_connect(%{name: name} = state) do
    if :undefined == :global.whereis_name(name) do
      :yes = :global.register_name(name, self())
    end
    {:ok, state}
  end
  def handle_disconnect(_reason, state) do
    {:reconnect, 5000, state} 
  end
  def handle_in(%Hedwig.Message{} = msg, state) do
    Logger.info(inspect msg)
    PhxchatWeb.Endpoint.broadcast! "room:lobby", "message", %{text: msg.text, type: msg.type}
    {:dispatch, msg, state}
  end
  def handle_in(_msg, state) do
    {:noreply, state}
  end
end

Start this handler in lib/phxchat/application.ex

def start(_type, _args) do
    # List all child processes to be supervised
    children = [
      # Start the Ecto repository
      Phxchat.Repo,
      # Start the endpoint when the application starts
      PhxchatWeb.Endpoint,
      # Starts a worker by calling: Phxchat.Worker.start_link(arg)
      # {Phxchat.Worker, arg},
      {Phxchat.Handlers.Echo, []}
    ]

And finally output the receiving messages at web console by add this code in assets/js/socket.js

let channel = socket.channel("room:lobby", {})
channel.join()
  .receive("ok", resp => { console.log("Joined successfully", resp) })
  .receive("error", resp => { console.log("Unable to join", resp) })
channel.on("message", (msg) => {
  console.log(msg);
})

You can use another user to talk to this bot now and receive message from phoenix.