documentation generated from TS

For the purposes of the present document, the following abbreviations apply:

* API: Application Programming Interface

* IoT: Internet of Things

* ISA²: Interoperability solutions for public administrations, businesses and citizens

* KPI: Key Performance Indicator

* OWL: Web Ontology Language

* OWL-DL: Web Ontology Language - Description Logic

* RDF: Resource Description Framework

* RDF-S: Resource Description Framework Schema

* SAREF: Smart Applications REFerence ontology

* SAREF4CITY: SAREF extension for the Smart Cities domain

* TR: Technical Report

* TS: Technical Specification

* UML: Unified Modelling Language

* W3C<sup>®</sup>:	World Wide Web Consortium

 No newline at end of file

<div class="alert-warning">NOTE: The text in this section is extracted from ETSI TS 103 410-4 (V2.1.1) <a href="#[0]">[0]</a>, and therefore falls inside the <a href="https://www.etsi.org/intellectual-property-rights">ETSI IPR Policy</a></div>

# SAREF4CITY ontology and semantics

The present document is a technical specification of SAREF4CITY, an OWL-DL ontology that extends SAREF <a href="#[1]">[1]</a>  for the Smart Cities domain. 

## Introduction and overview

SAREF4CITY V2.1.1 is a major revision of SAREF4CITY, using updated reference ontology patterns specified in ETSI TS 103 548 <a href="#[2]">[2]</a>  to solve the harmonization needs identified in ETSI TR 103 781 <a href="#[i.2]">[i.2]</a> , with updated development framework and tools defined in ETSI TS 103 673 <a href="#[i.3]">[i.3]</a> .

This extension has been created by investigating resources from potential stakeholders of the ontology, such as standardization bodies (e.g. Open Geospatial Consortium), associations (e.g. Spanish Federation of Municipalities and Provinces), IoT platforms (e.g. FIWARE) and European projects and initiatives (e.g. ISA2 programme) as reported in ETSI TR 103 506 <a href="#[i.1]">[i.1]</a> . In addition, the use cases defined in <a href="#[i.1]">[i.1]</a>  were also taken into account, namely:

The present document is a technical specification of SAREF4CITY, an OWL-DL ontology that extends SAREF [1] for the Smart Cities domain. 

* Use case 1: eHealth and Smart Parking.

* Use case 2: Air Quality Monitoring and Mobility.

* Use case 3: Street Lighting, Air Quality Monitoring and Mobility.

Taking into account ontologies, data models, standards and datasets provided by the identified stakeholders, a set of requirements were identified and grouped in the following categories: Topology, Administrative Area, City Object, Event, Measurement, Key Performance Indicator, and Public Service. Such requirements and categories were validated during the "SAREF4CITY Validation Workshop" at the IoT Week in Bilbao on the 4th of June 2018. During the workshop, attendees validated the use cases proposed above and the list of requirements for the above-mentioned categories. According to the feedback and outcomes of the workshop, some actions were taken such as to discard some requirements, to eliminate duplicates, to clarify requirements, or to add new ones. The concrete decisions were reported in ETSI TR 103 506 <a href="#[i.1]">[i.1]</a> . The requirements listed in such document were taken as input for the ontology development. More precisely, the ontology conceptualization was done in a modular way in which one pattern was defined for each of the abovementioned categories. 

SAREF4CITY V2.1.1 is a major revision of SAREF4CITY, using updated reference ontology patterns specified in ETSI TS 103 548 [2] to solve the harmonization needs identified in ETSI TR 103 781 [i.2], with updated development framework and tools defined in ETSI TS 103 673 [i.3].

This extension has been created by investigating resources from potential stakeholders of the ontology, such as standardization bodies (e.g. Open Geospatial Consortium), associations (e.g. Spanish Federation of Municipalities and Provinces), IoT platforms (e.g. FIWARE) and European projects and initiatives (e.g. ISA<sup>2</sup> programme) as reported in ETSI TR 103 506 [i.1]. In addition, the use cases defined in [i.1] were also taken into account, namely:

* **Use case 1:** eHealth and Smart Parking.

* **Use case 2:** Air Quality Monitoring and Mobility.

* **Use case 3:** Street Lighting, Air Quality Monitoring and Mobility.

Taking into account ontologies, data models, standards and datasets provided by the identified stakeholders, a set of requirements were identified and grouped in the following categories: Topology, Administrative Area, City Object, Event, Measurement, Key Performance Indicator, and Public Service. Such requirements and categories were validated during the "SAREF4CITY Validation Workshop" at the IoT Week in Bilbao on the 4th of June 2018. During the workshop, attendees validated the use cases proposed above and the list of requirements for the above-mentioned categories. According to the feedback and outcomes of the workshop, some actions were taken such as to discard some requirements, to eliminate duplicates, to clarify requirements, or to add new ones. The concrete decisions were reported in ETSI TR 103 506 [i.1]. The requirements listed in such document were taken as input for the ontology development. More precisely, the ontology conceptualization was done in a modular way in which one pattern was defined for each of the abovementioned categories. 

After the first complete implementation of the ontology, a second validation workshop, the "Towards interoperability and harmonization of Smart City models with SAREF4CITY" one, took place on the 22nd of November 2018 at the European Commission premises in Brussels. During the workshop, the ontology was presented to a variety of stakeholders from industry to academia and public administration. Apart from observations and comments on the reuse and alignment with other ontologies, the discussion addressed more general questions like how to promote the adoption of SAREF or which is the technological and methodological support needed to create a SAREF ecosystem of collaborative ontologies.

The current version of the ontology, V2.1.1, represents the adaptation of the previous SAREF4CITY conceptualization according to the new SAREF core and the homogenization process across extensions.

SAREF4CITY is an OWL-DL ontology that extends SAREF and reuses seven other ontologies. SAREF4CITY includes 124 classes (13 defined in SAREF4CITY and 111 reused from the SAREF, time, sf, geo, foaf, dc, org, cpsv, skos and time ontologies), 103 object properties (18 defined in SAREF4CITY and 85 reused from the SAREF, geo, skos and cpsv ontologies) and 13 data type properties (6 defined in SAREF4CITY and 4 reused from the SAREF ontology).

SAREF4CITY focuses on extending SAREF in order to create a common core of general concepts for smart city data oriented to the IoT field. The main idea is to identify the core components, as mentioned, that could be extended for particular smart city subdomains, for example, for public transport.

The prefixes and namespaces used in SAREF4CITY and in the present document are listed in [the Namespace Declarations section](#namespacedeclarations).

The prefixes and namespaces used in SAREF4CITY and in the present document are listed in Table 1.

{{table_1}}

 No newline at end of file

<p><a href="#Figure_8">Figure 8</a> shows an example of how to instantiate the SAREF4CITY extension of SAREF. This example shows the use of different patterns included in the SAREF4CITY ontology. First of all, a camera (ex:Camera1) measures the speed of a car (ex:Car35) in the information attached to the individual ex:Camera1Measurement200, which provides a value of 35 Km/hour. The position of the car at that moment is captured by the instance ex:CarLocation2018-11-20T13-30-00 with points to the geographical coordinates in which the car is located and also to the road segment in which it is included. It can be observed that such road segment might contain (see property geo:sf:Contains) other city objects such as a lamppost or a building.</p>

<p>The KPI pattern is also instantiated in the example. The instance ex:RoadSegment50Congestion2018-11-20T13-30-00 refer to the value (70 %) of the road congestion on the 2018-11-20 at 13:20. Such value is assessed by the public administration ex:City4. In the calculation of such value the speed of the cars (ex:CarsSpeed2018-11-20), the pollution (ex:Polution2018-11-20) and the GMaps API (ex:GMapsAPI2018-11-20) values have been taken into account as it can be observed from the s4city:isDerivedFrom property between the KPI value and the different saref:Observation instances.</p>

<p>In the example the event ex:BasketMatch23, as sub event of the ex:BasketWeek2018, is described. It can be seen that the match is accessible by metro, is organized by ex:City4 and takes place at the facility ex:BasketArena7.

Finally, some examples of public services are shown. One service example is the ex:HealthService123 that involves the facility ex:BasketArena7 and is available in Spanish. Such service is available in area ex:Neighbourhood34 that is contained in ex:City4, which is the service provider organization. In addition, another service, ex:BusService33, is provided by another organization, in this case ex:TransportCo.</p>

<figure>

  <a href="diagrams/S4CITY Example 1.png"><img src="diagrams/S4CITY Example 1.png" alt="Road Congestion exampleexample"/></a>

  <figcaption id="Figure_8">Figure 8: Road Congestion example</figcaption>

</figure>

## Instantiating SAREF4CITY

Figure 8 shows an example of how to instantiate the SAREF4CITY extension of SAREF. This example shows the use of different patterns included in the SAREF4CITY ontology. First of all, a camera (`ex:Camera1`) measures the speed of a car (`ex:Car35`) in the information attached to the individual `ex:Camera1Measurement200`, which provides a value of 35 Km/hour. The position of the car at that moment is captured by the instance `ex:CarLocation2018-11-20T13-30-00` with points to the geographical coordinates in which the car is located and also to the road segment in which it is included. It can be observed that such road segment might contain (see property `geo:sf:Contains`) other city objects such as a lamppost or a building.

The KPI pattern is also instantiated in the example. The instance `ex:RoadSegment50Congestion2018-11-20T13-30-00` refer to the value (70 %) of the road congestion on the 2018-11-20 at 13:20. Such value is assessed by the public administration `ex:City4`. In the calculation of such value the speed of the cars (`ex:CarsSpeed2018-11-20`), the pollution (`ex:Polution2018-11-20`) and the GMaps API (`ex:GMapsAPI2018-11-20)` values have been taken into account as it can be observed from the `s4city:isDerivedFrom` property between the KPI value and the different `saref:`Observation instances.

In the example the event `ex:BasketMatch23`, as sub event of the `ex:BasketWeek2018,` is described. It can be seen that the match is accessible by metro, is organized by `ex:City4` and takes place at the facility `ex:BasketArena7.`

Finally, some examples of public services are shown. One service example is the `ex:HealthService123` that involves the facility `ex:BasketArena7` and is available in Spanish. Such service is available in area `ex:Neighbourhood34` that is contained in `ex:City4`, which is the service provider organization. In addition, another service, `ex:BusService33,` is provided by another organization, in this case `ex:TransportCo`.

<figure id="Figure_8">

        <img data-docx-width="21.58cm" src="diagrams/S4CITY Example 1.png" alt="SAREF4CITY Road Congestion example"/>

        <figcaption>Figure 8: SAREF4CITY Road Congestion example</figcaption>

    </figure>