Chapter 8: Building a Smart Productivity Cube, Part 2

1. MQTT apps for iOS and Android can be used to both display and send MQTT messages. Their purpose is to build a personal dashboard that allows you to consume all of the important information published by your MQTT devices and to control them by publishing messages as well.
2. To send just the activity time (without the activity name), you have to change the client.publish("/tims-channel/cube/activity", text); line to client.publish("/tims-channel/cube/activity", timeSpend);.
3. A good client ID, to be compatible with most MQTT clients and servers, should be no longer than 23 characters and only contain regular characters (a-z, 0-9, and -). Also, you should make sure that nobody else is using the same name on the same MQTT server. The easiest way is just by appending a few random digits to your client ID (for example, your-name-184638).