Add Elixir source for tutorial 4

elixir/emit_log_direct.exs

@@ -0,0 +1,28 @@
+{:ok, connection} = AMQP.Connection.open
+{:ok, channel} = AMQP.Channel.open(connection)
+
+{severities, raw_message, _} = 
+  System.argv
+  |> OptionParser.parse(strict: [info:    :boolean,
+                                 warning: :boolean,
+                                 error:   :boolean])
+  |> case do
+    {[], msg, _} -> {[info: true], msg, []}
+    other -> other
+  end
+
+message = 
+  case raw_message do
+    []    -> "Hello World!"
+    words -> Enum.join(words, " ")
+  end
+
+AMQP.Exchange.declare(channel, "direct_logs", :direct)
+
+for {severity, true} <- severities do
+  severity = severity |> to_string
+  AMQP.Basic.publish(channel, "direct_logs", severity, message)
+  IO.puts " [x] Sent '[#{severity}] #{message}'"
+end
+
+AMQP.Connection.close(connection)

elixir/receive_logs_direct.exs

@@ -0,0 +1,35 @@
+defmodule ReceiveLogsDirect do
+  def wait_for_messages(channel) do
+    receive do
+      {:basic_deliver, payload, meta} ->
+        IO.puts " [x] Received [#{meta.routing_key}] #{payload}"
+
+        wait_for_messages(channel)
+    end
+  end
+end
+
+{:ok, connection} = AMQP.Connection.open
+{:ok, channel} = AMQP.Channel.open(connection)
+
+{severities, _, _} = 
+  System.argv
+  |> OptionParser.parse(strict: [info:    :boolean,
+                                 warning: :boolean,
+                                 error:   :boolean])
+
+AMQP.Exchange.declare(channel, "direct_logs", :direct)
+
+{:ok, %{queue: queue_name}} = AMQP.Queue.declare(channel, "", exclusive: true)
+
+for {severity, true} <- severities do
+  binding_key = severity |> to_string
+  AMQP.Queue.bind(channel, queue_name, "direct_logs", routing_key: binding_key)
+end
+
+AMQP.Basic.consume(channel, queue_name, nil, no_ack: true)
+
+IO.puts " [*] Waiting for messages. To exist press CTRL+C, CTRL+C"
+
+
+ReceiveLogsDirect.wait_for_messages(channel)