Publishing sensor data

Now that we have a live connection, we're ready to publish sampled sensor data. We will first need some member variables. These will store last values, last-published values, and the timestamps of last-published values:

private double? lastLight = null; 
private bool? lastMotion = null; 
private double? lastPublishedLight = null; 
private bool? lastPublishedMotion = null; 
private DateTimelastLightPublishTime = DateTime.MinValue; 
private DateTimelastMotionPublishTime = DateTime.MinValue; 

From our sampling and event methods where we receive and calculate our most recent sensor data, we call two new methods: PublishLight() and PublishMotion(). To illustrate different ways of publishing data, these two methods will publish the corresponding sensor data fields on individual topics, as strings. They will then individually call PublishLastJson(), which...