Report multiple Resources in a single Event and Stream

In the previous examples, data from each Resource was routed to a different Cloud Stream.
Depending on how you plan to handle the data on the cloud side, it can be beneficial to send most of your data in a single stream.

This is how to do so:

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Key Takeways

• in order to send Resource data in a single Event, you can use an Edge Action to collect the data and create the Event with the resource payload that you want
• one resource and EA Observation is used to trigger the EA
• other Resources can be ready from the EA:

  • directly via a Datahub.Read('resource') to get the latest value of a Resource
  • by calling an Observation via Datahub.query('observation'), thus benefiting from the Observation characteristics (filter, buffering, min/max/mean)

• the Event sent from the EA will be routed to the 'device/:default' stream

Here's a short example of an EA code handling this implementation:

function(event) {

return {
  "cl://": [{																								
    "temperature":  event.value,														
    "humidity":     Datahub.read('/humidity/value',0).value,
    "wind_speed":   Datahub.query('wind_speed','mean',10)
    }]
};

}

and this is what the Event looks like in the 'device/:default' stream:

{
 "elems": {
    "humidity": 31.3,
    "temperature": 37.4,
    "wind_speed": 17.7
  }
}

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Learning more:

• in order to report Events on a periodic basis rather than on an actual measurable Resource, a similar approach can be taken with 'util/counter/value' as the input Resource to trigger the EA
• by directing the EA output to "sf://" instead of "cl://" the Events will be handled by the S&F and sent according to its flushing rules.
• if you want to use a similar approach but send the data to another stream than 'device/:default', you can write rout EA output to a JSON VR and set a CS Observation on that VR