This Instructables show how you can connect Arduino YUN to the Adafriot IO platform for sharing the DHT-11 sensor value, the photoresistor value, and also control the led onboard, a relay, and a PWM output. The PWM outpout can control the brightness of a light or the speed of a motor.
For use an Arduino YUN with this Instructables, you must be connected the Arduino YUN to your lan and then to internet. If Arduino not's connected to internet, the Instructables not work.
The MQTT protocol is the best method for IoT now. It's simple, it's a complete method to connect the objects to the cloud, to the internet. Adafruit Industries have created a library and platform to use that protocol with Arduino ESP and other hardware.
For sfruttare this platform you must subscribe to Adafruit IO service. Go to Adafruit IO (http://www.io.adafruit.com/). Then Sign Up for free. Then follow the instructions. After you can see the Dashboard and try the functioning of Adafruit IO. Now you can create a new Dashboard using the button "Create Dashboard". You must naming the Dashboard "Arduino". After we add the values to the dashboard.