## 3. envi: Description back to ToC

Figure 1 provides a general overview of the SAREF4ENVI ontology.

Figure 1. - SAREF4ENVI general diagram.

### Instantiating SAREF4ENVI back to ToC

This section shows an example of an instantiation of the SAREF4ENVI ontology. Such example aims to illustrate how to describe a given sensor, in this case a photometer, using the SAREF4ENVI ontology. In addition, the example is complemented with energy consumption information for which the SAREF4ENER ontology is used. The example is graphically represented in Figure 2 and Figure 3 and the corresponding Turtle code is provided in example code.

The core part of the example, the information annotated by the SAREF4ENVI ontology, is depicted in Figure 2. In such figure a photometer named “stars5” is depicted by a purple box. This purple box represents the instance ex:TESS005-UC that belongs to the class s4envi:Tess. This photometer is named “stars5”, is manufactured by “Universidad Complutense de Madrid” and has version “1”, as indicated by the values of the datatype properties saref:hasName, saref:hasManufacturer and s4envi:hasVersion, respectively.

We can also see in Figure 2 that the photometer is located in a given point, represented by the instance ex:LocationTESS005-UCM, which has specific values for the geographical coordinates indicated by the properties geo:longitude and geo:latitude.

The communication protocol that the photometer uses is indicated by the object property s4envi:usesCommunicationProtocol which links the instance representing the photometer with an instance of the class s4envi:CommunicationProtocol named ex:MQTT-Broker that represents the protocol “MQTT Broker”. In addition, the photometer is able to use three different communication interfaces, namely RS232 v24, Bluetooth v2.1 and Wi-Fi v802.11ah. The photometer is linked to three different individuals that belong to the class s4envi:CommunicationInterface, each one representing one interface, by means of the property s4envi:usesCommunicationInterface. Each of these individuals has instantiated the datatype property s4envi:hasVersion in order to indicate the version of the communication interface.

The TESS photometer is able to measure light magnitude. It is indicated by the link between the photometer and the individual s4envi:LightMagnitude, which belongs to the class s4envi:LightProperty, using the property saref:measuresProperty.

The photometer has a frequency for taking one measurement every 10 seconds. This is represented by the property s4envi:hasFrequencyMeasurement that links the photometer with the instance ex:FrequencyMeasurementTESS005-UC which belongs to the class s4envi: FrequencyMeasurement. Such instance represents the value of the frequency by instantiating the datatype property saref:hasValue with the float value “10.0” and indicates the unit of measurement in which such value is measured by means of the object property saref:isMeasduredIn and the instance wurvoc:recriprocal_second-time reused from the OM ontology.

The photometer has a period for transmitting measurements of 30 seconds. This is represented by the property s4envi:hasTransmissionPeriod that links the photometer with the instance ex:PeriodTransmissionTESS005-UC, which belongs to the class s4envi:PeriodMeasurement. Such instance represents the value of the frequency by instantiating the datatype property saref:hasValue with the float value “30.0” and indicates the unit of measurement in which such value is measured by means of the object property saref:isMeasduredIn and the instance time:unitSecond reused from the time ontology.

The example also shows two measurements of light magnitude taken by the photometer. These measurements are represented by the instances ex:Measurement2016-10-05T08:15:30TESS005-UCM and ex:Measurement2016-10-05T08:15:40TESS005-UCM that belong to the class saref:Measurement. Such instances indicate which property the measurement is about by using the object property saref:relatesToProperty to link to the instance s4envi:LightMagnitude. The value of each measurement, “0.1” for the first one and “0.8” for the second one, is represented by the float value attached to the datatype property saref:hasValue. The unit of measurement in which the values are expressed is indicated by the instance ex:mgPerArcsec2. This instance is linked from the instance representing the measurement by the object property saref:isMeasuredIn. Finally, the time stamps when the measurements were taken are represented by the values linked from the datatype property saref:hasTimeStamp.

Figure 2. - Photometer TESS description example.

Figure 3 shows an example about combining ontological elements from the SAREF4ENVI ontology with the SAREF4ENER one. More precisely, it indicates the power consumption of the TESS photometer described above. For doing so, the instance representing the photometer, namely ex:TESS005-UCM, is linked to an instance named ex:PowerProfileTESS005-UCM that belongs to the class s4ee:PowerProfile which represents the power profile of the photometer. This latter instance indicates the photometer power consumption by linking, using the object property saref:hasConsumption, to an instance named ex:PowerTESS005-UCM that belongs to the class s4ener:Power. Finally, this instance indicates the power consumption value “20.0” by means of the datatype property saref:hasValue and the unit in which such value is measured by means of the object property saref:isMeasuredIn that points to the instance wurvoc:watt.

Figure 3. - Photometer TESS related to the energy extension example.