SAREF v3.1.1 is a reference ontology for the IoT developed by ETSI SmartM2M in close interaction with the industry. SAREF contains core concepts that are common to several IoT domains and, to be able to handle specific data elements for a certain domain, dedicated extensions of SAREF have been created, for example SAREF4ENER [i.4], SAREF4ENVI [i.5], SAREF4BLDG [i.6], and SAREF4CITY [i.7], SAREF4INMA [i.8], SAREF4AGRI [i.9]. Each domain can have one or more extensions, depending on the complexity of the domain. As a reference ontology, SAREF serves as the means to connect the extensions in different domains. The earlier document ETSI TR 103 411 [i.10] specifies the rationale and methodology used to create, publish and maintain the SAREF extensions.
The present document is the technical specification of SAREF4SYST, a generic extension of ETSI TS 103 264 SAREF  that defines an ontology pattern which can be instantiated for different domains. SAREF4SYST defines Systems, Connections between systems, and Connection Points at which systems may be connected. These core concepts can be used generically to define the topology of features of interest, and can be specialized for multiple domains. The topology of features of interest is highly important in many use cases. If a room holds a lighting device, and if it is adjacent with an open window to a room whose luminosity is low, then by turning on the lighting device in the former room one may expect that the luminosity in the latter room will rise.
The SAREF4SYST ontology pattern can be instantiated for different domains. For example to describe zones inside a building (systems), that share a frontier (connections). Properties of systems are typically state variables (e.g. agent population, temperature), whereas properties of connections are typically flows (e.g. heat flow).
SAREF4SYST has two main aims: on the one hand, to extend SAREF with the capability or representing general topology of systems and how they are connected or interact and, on the other hand, to exemplify how ontology patterns may help to ensure an homogeneous structure of the overall SAREF ontology and speed up the development of extensions.
SAREF4SYST consists both of a core ontology, and guidelines to create ontologies following the SAREF4SYST ontology pattern. The core ontology is a lightweight OWL-DL ontology that defines 3 classes and 9 object properties.
Use cases for ontology patterns are described extensively in ETSI TR 103 549 [i.3]. Clauses 4.2 and 4.3 extract use cases for the SAREF4SYST ontology pattern.
The present clause illustrates how SAREF4SYST can be used to homogeneously represent knowledge that is relevant for use cases in the Smart Energy domain:
The present clause illustrates how SAREF4SYST can be used to homogeneously represent knowledge that is relevant for use cases in the Smart Building domain:
A graphical overview of the SAREF4SYST ontology is provided in Figure 1. In such figure:
A s4syst:System, is defined as a part of the universe that is virtually isolated from the environment.
NOTE: The system properties are typically state variables (e.g. consumed or stored energy, agent population, temperature, volume, humidity).Figure 2 illustrates classes and properties that can be used to define connected systems and their sub-systems.
A system may be connected to other systems that are part of its environment. This is modelled by a property named s4syst:connectedTo, which is symmetric.
A connection between two s4syst:Systems, modelled by s4syst:connectedTo, describes the potential interactions between connected s4syst:Systems. A connection can be qualified using class s4syst:Connection.Figure 3 illustrates classes and properties that can be used to qualify connections between s4syst:Systems.
The editors would like to thank the ETSI SmartM2M technical committee for providing guidance and expertise.
Also, many thanks to the ETSI staff and all other current and former active Participants of the ETSI SmartM2M group for their support, technical input and suggestions that led to improvements to this ontology.
Also, special thanks goes to the ETSI SmartM2M Technical Officer Guillemin Patrick for his help.
This documentation page was generated automatically using SPARQL-Generate, developed by Maxime Lefrançois. The SAREF public portal, the SAREF sources with continuous integration and deployment, the SAREF Pipeline software, and ETSI Technical Specification TS 103 673 v1.1.1 "SAREF Development Framework and Workflow, Streamlining the Development of SAREF and its Extensions", have been developed in the context of the ETSI STF 578, which followed the ETSI STF 556.