Add simple MQTT support to subscribe to, publish messages.

Gemfile

@@ -74,6 +74,8 @@ gem 'slack-notifier', '~> 0.5.0'
 
 gem 'therubyracer', '~> 0.12.1'
 
+gem 'mqtt'
+
 group :development do
   gem 'binding_of_caller'
   gem 'better_errors'

Gemfile.lock

@@ -160,6 +160,7 @@ GEM
     mime-types (1.25.1)
     mini_portile (0.5.3)
     minitest (5.3.3)
+    mqtt (0.2.0)
     multi_json (1.9.3)
     multi_xml (0.5.5)
     multipart-post (2.0.0)
@@ -341,6 +342,7 @@ DEPENDENCIES
   kaminari (~> 0.15.1)
   kramdown (~> 1.3.3)
   liquid (~> 2.6.1)
+  mqtt
   mysql2 (~> 0.3.15)
   nokogiri (~> 1.6.1)
   protected_attributes (~> 1.0.7)

app/models/agents/mqtt_agent.rb

@@ -0,0 +1,112 @@
+# encoding: utf-8 
+require "mqtt"
+
+module Agents
+  class MqttAgent < Agent
+    description <<-MD
+    The MQTT agent allows both publication to an MQTT topic and subscription to an MQTT topic.
+
+    Setup your own broker (http://jpmens.net/2013/09/01/installing-mosquitto-on-a-raspberry-pi/) or connect to a cloud service (www.cloudmqtt.com).
+
+    MQTT is a generic transport protocol for machine to machine communication.
+
+    You can do things like:
+
+     * Publish to [RabbitMQ](http://www.rabbitmq.com/mqtt.html)
+     * Run [OwnTracks, a location tracking tool](http://owntracks.org/) for iOS and Android
+     * Subscribe to your home automation setup like [Ninjablocks](http://forums.ninjablocks.com/index.php?p=/discussion/661/today-i-learned-about-mqtt/p1) or [TheThingSystem](http://thethingsystem.com/dev/supported-things.html)
+
+    Simply choose a topic (think email subject line) to publish/listen to, and configure your service.
+
+    Hints:
+    Many services run mqtts (mqtt over SSL) often with a custom certificate.
+
+    You'll want to download their cert and install it locally, specifying the ```certificate_path``` configuration.
+
+
+    Example configuration:
+
+    <pre><code>{
+      'uri' => 'mqtts://user:pass@locahost:8883'
+      'ssl' => :TLSv1,
+      'ca_file' => './ca.pem',
+      'cert_file' => './client.crt',
+      'key_file' => './client.key',
+      'topic' => 'huginn'
+    }
+    </code></pre>
+
+    Subscribe to CloCkWeRX's TheThingSystem instance (thethingsystem.com), where
+    temperature and other events are being published.
+
+    <pre><code>{
+      'uri' => 'mqtt://kcqlmkgx:sVNoccqwvXxE@m10.cloudmqtt.com:13858'
+      'topic' => 'the_thing_system/demo'
+    }
+    </code></pre>
+
+    Subscribe to all topics
+    <pre><code>{
+      'uri' => 'mqtt://kcqlmkgx:sVNoccqwvXxE@m10.cloudmqtt.com:13858'
+      'topic' => '/#'
+    }
+    </code></pre>
+
+    Find out more detail on [subscription wildcards](http://www.eclipse.org/paho/files/mqttdoc/Cclient/wildcard.html)
+
+    MD
+
+    def validate_options
+      # unless options['uid'].present? &&
+      #   options['expected_update_period_in_days'].present?
+      #   errors.add(:base, "expected_update_period_in_days and uid are required")
+      # end
+    end
+
+    def working?
+      !recent_error_logs?
+    end
+
+    def default_options
+      {
+        'uri' => 'mqtts://user:pass@locahost:8883',
+        'ssl' => :TLSv1,
+        'ca_file' => './ca.pem',
+        'cert_file' => './client.crt',
+        'key_file' => './client.key',
+        'topic' => 'huginn'
+      }
+    end
+
+    def mqtt_client
+      client = MQTT::Client.new(options['uri'])
+
+      if options['ssl']
+        client.ssl = options['ssl'].to_sym
+        client.ca_file = options['ca_file']
+        client.cert_file = options['cert_file']
+        client.key_file = options['key_file']
+      end
+
+      client
+    end
+
+    def receive(incoming_events)
+      mqtt_client.connect do |c|
+        incoming_events.each do |event|
+          c.publish(options['topic'], payload)
+        end
+      end
+    end
+
+
+    def check
+      mqtt_client.connect do |c|
+        c.get(options['topic']) do |topic,message|
+          create_event :payload => { 'topic' => topic, 'message' => message, 'time' => Time.now.to_i }
+        end
+      end
+    end
+
+  end
+end