Merge remote-tracking branch 'origin/issue-25' into develop-v2.1.1

<h3>Platform, System and Deployment</h3>

<p>The model defined in SAREF4AGRI for representing platforms, systems and deployments is depicted in <a href="#Figure_2">Figure 2</a>. The main entities in the modelling are represented by the <a href="http://www.w3.org/ns/ssn/System">ssn:System</a> and <a href="http://www.w3.org/ns/ssn/Deployment">ssn:Deployment</a> classes. Note that the design patterns for modelling these concepts have been taken from the W3C SSN ontology and, as a best practice for reuse, the SAREF4AGRI model refers directly to the URIs of the SSN (<a href="http://www.w3.org/ns/ssn/">http://www.w3.org/ns/ssn/</a>) and SOSA (<a href="http://www.w3.org/ns/sosa/">http://www.w3.org/ns/sosa/</a>) ontologies. </p>

<p>The <a href="http://www.w3.org/ns/ssn/System">ssn:System</a> class in the SSN ontology represents a system and is components as specific devices, actuators or sensors. Moreover, the <a href="http://www.w3.org/ns/ssn/Deployment">ssn:Deployment</a> class from the SSN ontology describes the deployment of one or more systems on a <a href="http://www.w3.org/ns/sosa/Platform">ssn:Platform</a> for a particular purpose for a given time period. SAREF4AGRI defines a <a href="https://saref.etsi.org/core/Device">saref:Device</a> as subclass of an <a href="http://www.w3.org/ns/ssn/System">ssn:System</a> and extends the <a href="http://www.w3.org/ns/ssn/Deployment">ssn:Deployment</a> class by means of the <a href="#s4agri:Deployment">s4agri:Deployment</a> class. In this way, it is possible to represent a specific installation of a certain agricultural system (e.g. a smart irrigation system) in a given space (expressed by means of the property <a href="#s4agri:hasDeploymentPeriod">s4agri:hasDeploymentPeriod</a>) and at a given temporal frame (expressed by means of the property <a href="#s4agri:isDeployedAtSpace">s4agri:isDeployedAtSpace</a>) where SAREF4AGRI devices (e.g. a pluviometer, a soil tensiometer, a weather station and a watering gun) can be deployed. The deployment can involve a given <a href="http://www.w3.org/ns/sosa/Platform">ssn:Platform</a> which hosts the system deployed in such deployment. In order to represent temporal information the TIME ontology has been reused. For the geographical information both the GeoSPARQL ontology (<a href="http://www.opengis.net/ont/geosparql#">http://www.opengis.net/ont/geosparql#</a>) and the WGS84 Geo vocabulary (<a href="http://www.w3.org/2003/01/geo/wgs84_pos#">http://www.w3.org/2003/01/geo/wgs84_pos#</a>) are reused.</p>

<p>The <a href="http://www.w3.org/ns/ssn/System">ssn:System</a> class in the SSN ontology represents a system and is components as specific devices, actuators or sensors. Moreover, the <a href="http://www.w3.org/ns/ssn/Deployment">ssn:Deployment</a> class from the SSN ontology describes the deployment of one or more systems on a <a href="http://www.w3.org/ns/sosa/Platform">ssn:Platform</a> for a particular purpose for a given time period. SAREF4AGRI defines a <a href="https://saref.etsi.org/core/Device">saref:Device</a> as subclass of an <a href="http://www.w3.org/ns/ssn/System">ssn:System</a> and extends the <a href="http://www.w3.org/ns/ssn/Deployment">ssn:Deployment</a> class by means of the <a href="#s4agri:Deployment">s4agri:Deployment</a> class. In this way, it is possible to represent a specific installation of a certain agricultural system (e.g. a smart irrigation system) in a given space (expressed by means of the property <a href="#s4agri:isDeployedAtSpace">s4agri:isDeployedAtSpace</a>) and at a given temporal frame (expressed by means of the property <a href="#s4agri:hasDeploymentPeriod">s4agri:hasDeploymentPeriod</a>) where SAREF4AGRI devices (e.g. a pluviometer, a soil tensiometer, a weather station and a watering gun) can be deployed. The deployment can involve a given <a href="http://www.w3.org/ns/sosa/Platform">ssn:Platform</a> which hosts the system deployed in such deployment. In order to represent temporal information the TIME ontology has been reused. For the geographical information both the GeoSPARQL ontology (<a href="http://www.opengis.net/ont/geosparql#">http://www.opengis.net/ont/geosparql#</a>) and the WGS84 Geo vocabulary (<a href="http://www.w3.org/2003/01/geo/wgs84_pos#">http://www.w3.org/2003/01/geo/wgs84_pos#</a>) are reused.</p>

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