Explanation: RESTful API that allows us to control electronic components connected to our Intel Galileo Gen 2 board through HTTP requests.

Explanation: MQTT was known as MQ Telemetry Transport protocol. MQTT is a lightweight protocol that runs on top of the TCP/IP protocol.

Explanation: We want to send and receive data in real time through internet and RESTful API is not the most appropriate option to do this. Instead, we will work on MQTT which is lighter than HTTP.

Explanation: The MQTT protocol is a machine to machine and Internet of thing connectivity protocol.

Explanation: MQTT is a lightweight protocol that runs on top of the TCP/IP protocol and works with publish subscribe mechanism.

Explanation: It is necessary to generate our PubNub publishes and subscribes keys in order to send and receive messages in the network.

Explanation: Click on Demo keyset pane and PubNub will display public, subscribe, and secret keys. We must copy and paste each of these keys to use them in our code that will publish messages and subscribe to them.

Explanation: The messageChannel class declares the command_key class attribute that defines the key string that defines what the code will understand as the command.

Explanation: __Init__ method saves the received arguments in three attributes with the same names.

Explanation: Then, the constructor declares two local variables: public_key and subscribe_key. These local variables save the public and subscribe keys that we had generated with the PubNub Admin portal.

Callback: specifies the function that will be called when there is a new message received from the channel.

Error: specifies the function that will be called on an error event.

Connect: specifies the function that will be called when a successful connection with the PubNub cloud.

Reconnect: specifies the function that will be called when a successful re-connection is completed with the PubNub cloud.

Disconnect: specifies the function that will be called when the client disconnects from the PubNub cloud.