Creating alarms based on the fragment

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1

Hi,

I have a couple of I/O i am reading both temperature and humidity data from, and i would like to trigger an alarm within Cumulocity once a certain threshold has been exceeded. I know i can use Smart Rules for this but when i have 20+ data points, this can be a bit tedious. i was wondering if can i be able to use Apama EPL for Cumulocity to filter out the measurements based on the fragment alone and ignore the series?! For example i have the fragments “gmj_Temperature” and “gmj_Humidity” which i would like to implement the alarms fro if a certain threshold is exceeded.

2

Can you help understand your use case by answering below queries?

  • Would both fragments be part of a single measurement or are they sent individually ? would there be multiple series for each fragment ?
  • How should these measurement fragments be correlated ? Are you expecting to raise alarm only when both these are above a threshold or do you want to raise alarms even if one of the values is beyond a threshold ?
  • If measurements are sent individually, What basis should be used to correlate individual measurements ? will measurement creation ‘time’ be the same for both sensors ?
  • Do you expect the measurements to arrive out of order ?
3

Hi Ravish,

I will be responding to your questions in their order:

  1. The fragments are not from a single measurement but they are separate and there are multiple series within each fragment.

  2. For each fragment there is a constant threshold level, so at any point where any one of the thresholds is exceeded by any of the values in a series i would like to trigger an alarm.

  3. Yes, the time for the measurements will be the same as both sensors are connected to the same client.

  4. I expect the measurements to be ordered according to their series, if am understanding your question correctly.

4

Thanks Vuyo,

You can subscribe to receive MeasurementFragment to listen to each fragments and series in a measurement. Depending on your data and use case you can use either one of the solution:

Scenario 1:
If you are expecting only few measurements to cross the threshold value and the fragments for which you want to check threshold is a static:

using com.apama.cumulocity.MeasurementFragment;


monitor MySampleMonitor {
    /** Initialize the application */
	dictionary<string, float> fragmentThreshold := {"gmj_Temperature":10.0, "gmj_Humidity":20.0};
    action onload() {
        // Application starts here
        monitor.subscribe(MeasurementFragment.SUBSCRIBE_CHANNEL);
        string fragment;
        for fragment in fragmentThreshold.keys() {
        	   on all MeasurementFragment(valueFragment=fragment, value > fragmentThreshold[fragment]) {
        		   // Create and send alarm
        	   }
        	   
        }
    }
}

Scenario 2 :
If you are expecting many measurements to cross the threshold value or the fragments for which you want to check threshold is a dynamic:

using com.apama.cumulocity.MeasurementFragment;


monitor MySampleMonitor {
    /** Initialize the application */
	dictionary<string, float> fragmentThreshold := {"gmj_Temperature":10.0, "gmj_Humidity":20.0};
    action onload() {
        // Application starts here
        monitor.subscribe(MeasurementFragment.SUBSCRIBE_CHANNEL);
        from mf in all MeasurementFragment() where fragmentThreshold.hasKey(mf.valueFragment) and mf.value > fragmentThreshold[mf.valueFragment] select mf as mf {
                // Create and send alarm
        }
    }
}

Scenario 3:
If you need to perform some aggregation as well before generating an alarm


using com.apama.cumulocity.MeasurementFragment;

monitor MySampleMonitor {
    /** Initialize the application */
       dictionary<string, float> fragmentThreshold := {"gmj_Temperature":10.0, "gmj_Humidity":20.0};
    action onload() {
        // Application starts here
        monitor.subscribe(MeasurementFragment.SUBSCRIBE_CHANNEL);
        on all MeasurementFragment() as mf{
             if(fragmentThreshold.hasKey(mf.valueFragment) and mf.value > fragmentThreshold[mf.valueFragment]) {
                // Create and send alarm
            }
        }
    }
}

Kindly make below update in the files mentioned to enable receiving MeasurementFragment :

CumulocityIoT.yaml:
startChains:
CumulocityIoT:
… …
- ApamaConnectivityForCumulocityIoT:
… …
measurementFormat: ${CUMULOCITY_MEASUREMENT_FORMAT}

CumulocityIoT.properties:
#set cumulocity measurement format
CUMULOCITY_MEASUREMENT_FORMAT=BOTH