ETSI GR CIM 021 V1.1.1 (2022-08)

cross-cutting Context Information Management (CIM); usage of external data models with NGSI-LD API

DGR/CIM-0021

General Information

• Status: Not Published
• Technical Committee: CIM - cross-cutting Context Information Management
• Current Stage: 12 - Completion
• Due Date: 30-Aug-2022
• Completion Date: 23-Aug-2022

Standards Content (Sample)

GROUP REPORT
cross-cutting Context Information Management (CIM);
usage of external data models with NGSI-LD API
Disclaimer
The present document has been produced and approved by the cross-cutting Context Information Management (CIM) ETSI
Industry Specification Group (ISG) and represents the views of those members who participated in this ISG.
It does not necessarily represent the views of the entire ETSI membership.

2 ETSI GR CIM 021 V1.1.1 (2022-08)

Reference
DGR/CIM-0021
Keywords
API, data models, Digital Twins, NGSI-LD
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ETSI
3 ETSI GR CIM 021 V1.1.1 (2022-08)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
Executive summary . 5
Introduction . 6
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 7
3 Definition of terms, symbols and abbreviations . 11
3.1 Terms . 11
3.2 Symbols . 11
3.3 Abbreviations . 11
4 Existing Relevant Semantic Models . 13
4.1 Classification of Data Models . 13
4.2 SAREF Family . 13
4.2.1 SAREF Core . 13
4.2.2 SAREF Extensions . 14
4.2.2.1 Introduction . 14
4.2.2.2 SAREF4CITY . 14
4.2.2.3 SAREF4ENER . 14
4.2.2.4 SAREF4WATR . 14
4.2.2.5 SAREF4EHAW . 15
4.2.2.6 SAREF4BLDG . 15
4.2.2.7 SAREF4INMA . 15
4.2.2.8 SAREF4AGRI . 15
4.2.2.9 SAREF4AUTO . 16
4.2.2.10 SAREF4WEAR . 16
4.2.2.11 SAREF4LIFT . 16
4.2.2.12 SAREF4SYST . 17
4.2.2.13 SAREF4ENVI . 17
4.2.3 Common features . 17
4.3 Schema.org . 18
4.4 Thesauri . 20
4.4.1 General Overview . 20
4.4.2 SKOS ontology . 21
4.4.3 Agrovoc . 21
4.5 SmartDataModels program . 21
4.5.1 General Overview . 21
4.5.2 Suggested methods to link external data . 22
4.6 OGC GeoSPARQL. 25
4.6.1 General Overview . 25
4.6.2 The ontology . 26
4.6.3 SPARQL extension functions . 27
4.7 Friend of a friend (FoaF) . 28
4.8 Data Catalogue Vocabulary (DCAT) . 29
4.9 WoT . 30
5 Using External Models in NGSI-LD . 30
5.1 Introduction and Goals . 30
5.2 Mapping Semantic concepts in NGSI-LD . 32
5.2.1 Review and classification of all different semantic technologies for representing data models . 32
5.2.1.1 Overview . 32
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5.2.1.2 Mapping SAREF ontology to NGSI-LD . 32
5.2.1.3 Mapping FoaF ontology to NGSI-LD . 33
5.2.1.4 Mapping DCAT ontology to NGSI-LD . 34
5.2.1.5 Suggestions to map OWL and RDFS to NGSI-LD . 34
5.2.2 Suggestions to map SKOS ontology to NGSI-LD . 34
5.3 Using URIs to point to external models . 35
5.3.1 Link an external model with @context . 35
5.3.2 Entity multi-typing . 38
5.3.3 Attribute typing using @context . 40
5.3.4 Create a custom @context file . 44
5.3.5 Representing equivalence and hierarchy. 46
5.4 Representing schemas in NGSI-LD . 47
5.4.1 SQL . 47
5.4.2 GQL . 49
5.5 Federate diverse/heterogeneous semantic models in one system . 50
5.5.1 Challenges when merging semantic graphs with overlapping concepts . 50
5.5.2 @context order logic. 51
5.5.3 Use compact IRIs and prefixes . 52
5.6 System of Systems and graph representation . 52
5.7 Suggestions and Conclusions . 53
6 Possible additions to NGSI-LD specification. 55
6.1 What can be achieved in centralized vs. federated deployments? . 55
6.2 Representation of a schema . 55
6.3 Range for values of literals (integers, dates, enums) . 56
6.4 Query Language improvements . 57
6.4.1 Relationships and navigation in the NGSI-LD Property graph . 57
6.4.2 Query sub-Attributes values without giving the identifiers of the parent Attributes . 57
6.4.3 Add the missing Topological Functions . 57
6.4.4 Return enriched Entities with computed data . 58
6.4.5 Introduce the orderBy clause . 58
6.5 Add the special Property "label" . 58
6.6 Forbid scoped and local @context definitions . 59
Annex A: Change History . 60
History . 61

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Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The declarations
pertaining to these essential IPRs, if any, are publicly available for ETSI members and non-members, and can be
found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to
ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (https://ipr.etsi.org/).
Pursuant to the ETSI Directives including the ETSI IPR Policy, no investigation regarding the essentiality of IPRs,
including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not
referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become,
essential to the present document.
Trademarks
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ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its

Members. 3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and of the 3GPP
Organizational Partners. oneM2M™ logo is a trademark of ETSI registered for the benefit of its Members and of the ®
oneM2M Partners. GSM and the GSM logo are trademarks registered and owned by the GSM Association.
Foreword
This Group Report (GR) has been produced by ETSI Industry Specification Group (ISG) cross-cutting Context
Information Management (CIM).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Executive summary
The present document provides an analysis of a small representative of data models that maps different domains (Smart
Cities, Communities, Geo-spatial Objects, etc.) and that are defined in different technologies (OWL, SKOS, RDF,
JSON Schema). The goal of the analysis was to retrieve and formulate recommendations to use external data models
with NGSI-LD (see ETSI GS CIM 009 [i.26]). Recommendations come as examples, suggestions and guidelines to
allow users to link external data models inside NGSI-LD [i.26] Entities. Lastly, the analysis highlighted possible new
features to add inside NGSI-LD [i.26]. Each proposal comes with a brief description of the use case and the reasons to
support its addition inside the NGSI-LD [i.26] specification.
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Introduction
There is a tremendous amount of data models being developed the needs of businesses in all verticals. The complexity
of these models and the associated technologies can vary from simple tabular files (e.g. .csv) to complex OWL 2
ontologies. NGSI-LD aims at providing a cross-domain meta model based on property graphs together with an API to
interact with context information.
It is important to empower NGSI-LD users how to use various ontologies: it is not the intent to create new ontologies,
but to describe options to make use of external vocabularies, taxonomies, thesauri and ontologies within an NGSI-LD
context and to describe how to articulate them with the NGSI-LD graph-based meta-model and cross-domain ontology.
Some are relatively simple, providing multi-lingual definitions of terms in a structure way. This is the case of the
Agrovoc [i.17] thesaurus based on SKOS. Others adds restrictions on the fields of a data model, such as defining the
allowed data range of a data field. This is the case of the schema.org initiative. And others go further providing means
for reasoning over the data structure which can provide means for data quality control, new properties discovery, etc.
This is provided by for example, OWL 2 ontologies.
It is thus very important to make clear the potential of approaches listed above and illustrate their use within a
NGSI-LD deployment to increase the usage of the cross-domain capabilities of NGSI-LD, by using working examples.

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1 Scope
The present document considers a selection of relevant and representative knowledge organization systems, to provide
an illustrative basis of data schemas and vocabularies relevant to be used in a NGSI-LD context. It provides
recommendations on how to link external data models in NGSI-LD, considering the illustration of their use with the
NGSI-LD API in complex environments, such as system-of-system models for Digital Twins. The present document
also provides suggestions for changes or enhancements to the NGSI-LD specification (API and data model).
Unless expressly stated, the NGSI-LD version referenced in the present document is 1.5.1.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
nonspecific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI TS 103 264 (V3.1.1): "SmartM2M; Smart Applications; Reference Ontology and oneM2M
Mapping".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103200_103299/103264/03.01.01_60/ts_103264v030101p.pdf.
[i.2] ETSI TS 103 410-4 (V1.1.2): "SmartM2M; Extension to SAREF; Part 4: Smart Cities Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341004/01.01.02_60/ts_10341004v010102p.pdf.
[i.3] ETSI TS 103 410-1 (V1.1.2): "SmartM2M; Extension to SAREF; Part 1: Energy Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341001/01.01.02_60/ts_10341001v010102p.pdf.
[i.4] ETSI TS 103 410-10 (V1.1.1): "SmartM2M; Extension to SAREF; Part 10: Water Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341010/01.01.01_60/ts_10341010v010101p.pdf.
[i.5] ETSI TS 103 410-8 (V1.1.1): "SmartM2M; Extension to SAREF; Part 8: eHealth/Ageing-well
Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341008/01.01.01_60/ts_10341008v010101p.pdf.
[i.6] ETSI TR 103 509: "SmartM2M; SAREF extension investigation; Requirements for
eHealth/Ageing-well".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_tr/103500_103599/103509/01.01.01_60/tr_103509v010101p.pdf.
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8 ETSI GR CIM 021 V1.1.1 (2022-08)
[i.7] ETSI TS 103 410-3 (V1.1.2): "SmartM2M; Extension to SAREF; Part 3: Building Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341003/01.01.02_60/ts_10341003v010102p.pdf.
[i.8] ETSI TS 103 410-5 (V1.1.2): "SmartM2M; Extension to SAREF; Part 5: Industry and
Manufacturing domains".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341005/01.01.02_60/ts_10341005v010102p.pdf.
[i.9] ETSI TS 103 410-6 (V1.1.2): "SmartM2M; Extension to SAREF; Part 6: Smart Agriculture and
Food Chain Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341006/01.01.02_60/ts_10341006v010102p.pdf.
[i.10] ETSI TS 103 410-7 (V1.1.1): "SmartM2M; Extension to SAREF; Part 7: Automotive Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341007/01.01.01_60/ts_10341007v010101p.pdf.
[i.11] ETSI TS 103 410-9 (V1.1.1): "SmartM2M; Extension to SAREF; Part 9: Wearables Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341009/01.01.01_60/ts_10341009v010101p.pdf.
[i.12] ETSI TS 103 410-11 (V1.1.1): "SmartM2M; Extension to SAREF; Part 11: Lift Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341011/01.01.01_60/ts_10341011v010101p.pdf.
[i.13] ETSI TS 103 548 (V1.1.2): "SmartM2M; SAREF consolidation with new reference ontology
patterns, based on the experience from the SEAS project".
NOTE: Available at:
http://www.etsi.org/deliver/etsi_ts/103500_103599/103548/01.01.02_60/ts_103548v010102p.pdf.
[i.14] ETSI TS 103 410-2 (V1.1.2): "SmartM2M; Extension to SAREF; Part 2: Environment Domain".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_ts/103400_103499/10341002/01.01.02_60/ts_10341002v010102p.pdf.
[i.15] Schema.org About Web Page.
NOTE: Available at: https://schema.org/docs/about.html.
[i.16] SKOS Simple Knowledge Organization System RDF Schema.
NOTE: Available at: https://www.w3.org/TR/2008/WD-skos-reference-20080829/skos.html.
[i.17] Agrovoc About Web Page.
NOTE: Available at: https://agrovoc.fao.org/browse/en/about.
[i.18] Smart Data Models About Web Page.
NOTE: Available at: https://smartdatamodels.org/index.php/about/. ®
[i.19] W3C DCAT2 (V2): "Data Catalog Vocabulary (DCAT) - Version 2".
NOTE: Available at: https://www.w3.org/TR/vocab-dcat-2/.
[i.20] CIDOC-CRM (V7.2): "Volume A: Definition of the CIDOC Conceptual Reference Model".
NOTE: Available at: https://www.cidoc-crm.org/sites/default/files/cidoc_crm_version_7.2.pdf.
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[i.21] OGC 11-052r4 (V1.0): "OGC GeoSPARQL - A Geographic Query Language for RDF Data".
NOTE: Available at: http://www.opengis.net/doc/IS/geosparql/1.0.
[i.22] OGC 11-052r5 (V1.1): "OGC GeoSPARQL - A Geographic Query Language for RDF Data".
NOTE: Available at: https://opengeospatial.github.io/ogc-geosparql/geosparql11/spec.html.
[i.23] INSPIRE-MIF (V0.1): "INSPIRE UML-to-GeoJSON encoding rule".
NOTE: Available at:
https://github.com/INSPIRE-MIF/2017.2/blob/master/GeoJSON/geojson-encoding-rule.md.
[i.24] FoaF (V0.1): "INSPIRE UML-to-GeoJSON encoding rule".
NOTE: Available at:
https://github.com/INSPIRE-MIF/2017.2/blob/master/GeoJSON/geojson-encoding-rule.md.
[i.25] WoT (V0.1): "INSPIRE UML-to-GeoJSON encoding rule".
NOTE: Available at:
https://github.com/INSPIRE-MIF/2017.2/blob/master/GeoJSON/geojson-encoding-rule.md.
[i.26] ETSI GS CIM 009 (V1.5.1): "Context Information Management (CIM); NGSI-LD API".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_gs/CIM/001_099/009/01.05.01_60/gs_CIM009v010501p.pdf.
[i.27] Maxat Kulmanov, Fatima Zohra Smaili, Xin Gao, Robert Hoehndorf: "Semantic similarity and
machine learning with ontologies, Briefings in Bioinformatics", Volume 22, Issue 4, July 2021,
bbaa199.
NOTE: Available at: https://doi.org/10.1093/bib/bbaa199.
[i.28] Ali Ayadi, Ahmed Samet, François de Bertrand de Beuvron, Cecilia Zanni-Merk: "Ontology
population with deep learning-based NLP: a case study on the Biomolecular Network Ontology,
Procedia Computer Science", Volume 159, 2019, ISSN 1877-0509.
NOTE: Available at: https://doi.org/10.1016/j.procs.2019.09.212.
[i.29] Jalila Filali, Hajer Baazaoui Zghal, Jean Martinet: "Ontology-Based Image Classification and
Annotation; International Journal of Pattern Recognition and Artificial Intelligence", 2020 34:11.
NOTE: Available at: https://www.researchgate.net/profile/Jean-Martinet/publication/337793103_Ontology-
Based_Image_Classification_and_Annotation/links/60210944299bf1cc26ae92bf/Ontology-Based-Image-
Classification-and-Annotation.pdf.
[i.30] J. Liu, X. Zhang, Y. Li, J. Wang and H. -J. Kim: "Deep Learning-Based Reasoning With Multi-
Ontology for IoT Applications", in IEEE™ Access, vol. 7, pp. 124688-124701, 2019.
NOTE: Available at: https://doi.org/10.1109/ACCESS.2019.2937353.
[i.31] H. Paulheim. Knowledge Graph Refinement:"A Survey of Approaches and Evaluation Methods",
Semantic Web Journal, (Preprint):1-20, 2016.
NOTE: Available at: http://www.semantic-web-journal.net/system/files/swj1167.pdf. ®
[i.32] Google , Advanced SEO: "Understand how structured data works".
NOTE: Available at: https://developers.google.com/search/docs/advanced/structured-data/intro-structured-
data?hl=en. ®
[i.33] W3C , JSON-LD (v1.1): "A JSON-based Serialization for Linked Data".
NOTE: Available at: https://www.w3.org/TR/json-ld11/.
ETSI
10 ETSI GR CIM 021 V1.1.1 (2022-08) ®
[i.34] Open Geospatial Consortium Inc. OGC 06-103r4: "OpenGIS Implementation Standard for
Geographic information - Simple feature access - Part 1: Common architecture".
NOTE: Available at: https://portal.opengeospatial.org/files/?artifact_id=25355.
[i.35] IEEE 802.15™ Working Group for Wireless Specialty Networks (WSN).
NOTE: Available at: https://www.ieee802.org/15.
[i.36] ISO/IEC CD 39075: "Information Technology - Database Languages - GQL".
[i.37] "Meet openCypher: The SQL for Graphs - Neo4j Graph Database". Neo4j Graph Database.
2015-10-21. Retrieved 2019-11-08.
NOTE: Available at: https://neo4j.com/blog/open-cypher-sql-for-graphs.
[i.38] ETSI TR 103 511: "SmartM2M; SAREF extension investigation; Requirements for AgriFood
domain".
[i.39] ETSI TR 103 508: "SmartM2M; SAREF extension investigation; Requirements for Automotive".
[i.40] ETSI TR 103 510: "SmartM2M; SAREF extension investigation; Requirements for Wearables".
[i.41] ETSI TR 103 546: "SmartM2M; Requirements & Feasibility study for Smart Lifts in IoT".
[i.42] ETSI TS 103 735: "SmartM2M; Smart Lifts IoT System".
[i.43] ISO 6523-1:1998: "Information technology -- Structure for the identification of organizations and
organization parts -- Part 1: Identification of organization identification schemes".
NOTE: See https://www.iso.org/standard/25773.html.
[i.44] IETF BCP 47.
NOTE: See https://tools.ietf.org/search/bcp47.
[i.45] ISO 17442:2019: "Financial services -- Legal entity identifier (LEI)".
NOTE: See https://www.iso.org/standard/75998.html.
[i.46] Website of DATEX II.
NOTE: Available at https://datex2.eu.
[i.47] ETSI GS CIM 006: "Context Information Management (CIM); Information Model (MOD0)".
NOTE: Available at:
https://www.etsi.org/deliver/etsi_gs/CIM/001_099/006/01.01.01_60/gs_CIM006v010101p.pdf.
[i.48] IEC 61850: "Communication networks and systems for power utility automation".
NOTE: Available at: https://webstore.iec.ch/publication/6028.
[i.49] ISO 19107:2019: "Geographic information -- Spatial schema".
[i.50] ISO 19156:2011: "Geographic information -- Observations and measurements".
[i.51] IETF RFC 7946: "The GeoJSON Format".
[i.52] STARS4ALL European H2020 project.
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3 Definition of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the following terms apply:
DATEX: European standard for the exchange of traffic information and traffic data [i.46]
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AEF Agricultural industry Electronics Foundation
API Application Programming Interface
ASC Ascending order
ASNE American Society of Newspaper Editors
BCP Best Current Practice
CIDOC Centro Intercultural de Documentación
CIDOC-CRM CIDOC Conceptual Reference Model
CIF Código de Identificación Fiscal
NOTE: The Tax/Fiscal ID of the organization or person in Spain (CIF/NIF).
DCAT Data Catalog Vocabulary (Version 1)
DCAT2 Data Catalog Vocabulary Version 2
DCAT-AP DCAT Application profile
DE-9IM Dimensionally Extended 9-Intersection Model
DTDL Digital Twins Definition Language
ECGs ElectroCardioGram(s)
EHAW eHEALTH and Ageing-Well
FAO Food and Agriculture Organization of the United Nations
FoaF Friend of a Friend
GBFS General Bikeshare Feed Specification
GeoJSON Geographic JSON
GeoSPARQL A Geographic Query Language for RDF Data
GIS Geographic Information System
GLN Global Location Number
GML Geography Markup Language
GQL Graph Query Language
GTFS General Transit Feed Specification
HTTP Hypertext Transfer Protocol
ICAR International Committee for Animal Recording
ID Identifier
IEEE Institute of Electrical and Electronics Engineers
IRI Internationalized Resource Identifier
IETF Internet Engineering Task Force
IFC Industry Foundation Classes
ILN International Location Number
IoT Internet of Things
ISIC International Standard of Industrial Classification of All Economic Activities
ISO International Organization for Standardization
ITS Intelligent Transport Systems
IUDX India Urban Data Exchange
JSON JavaScript Object Notation
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JSON-LD JSON Linked Data
JTC Joint Techncial Committee
NAICS North American Industry Classification System
NGSI Next Generation Service Interfaces
NGSI-LD NGSI-Linked Data
NIF Número de Identificación Fiscal
NOTE: The Tax/Fiscal ID of the organization or person in Spain (CIF/NIF).
NLP Natural Language Processing
OASC Open and Agile Smart Cities
OCF Open Connectivity Foundation
OGC Open Geospatial Consortium
OGC GeoSPARQL OGC Geographic Query Language for RDF Data
OM Ontology of units of Measure (OM ontology)
OWL Web Ontology Language
OWL-DL Web Ontology Language Description Logic
RAMI Reference Architecture Model for Industry
RDBMS Relational Database Management System
RDF Resource Description Format
RDFS Resource Description Framework Schema
RTDNA Radio Television Digital News Association
SAREF Smart Applications REFerence ontology
SAREF4CITY SAREF for Smart Cities
SAREF4ENER SAREF for Engergy
SAREF4WATR SAREF for Water
SAREF4EHAW SAREF for eHealth/Ageing-well
SAREF4BLDG SAREF for Building
SAREF4INMA SAREF for Industry and Manufacturing
SAREF4AGRI SAREF for Agriculture and Food Chain
SAREF4AUTO SAREF for Automotive
SAREF4WEAR SAREF for Wearables
SAREF4LIFT SAREF for Lift
SAREF4SYST SAREF for System
SAREF4ENVI SAREF for Environment
SC Sub Committee
SEO Search Engine Optimization
SKOS Simple Knowledge Organization System
SPARQL SPARQL Protocol and RDF Query Language
SQL Structured Query Language
TC Technical Committee
TCP/IP Transaction Control Protocol/Internet Protocol
TD Thing Description
TIN Taxpayer Identification Number
NOTE: Tax/fiscal ID of organization or person in USA.
URI Uniform Resource Identifier
URL Universal Resource Locator
USA United States of America
V2V Vehicle(s) to Vehicle(s) ®
W3C World Wide Web Consrtium ®
W3C SSN W3C Semantic Sensor Network
NOTE: W3C SSN ontology includes W3C SOSA. ®
W3C SOSA W3C Sensor, Observation, Sample, and Actuator
WG Working Group
WKT Well-Known Text
WoT Web of Things
WoT TD Web of Things Thing Description
WSN Wireless Specialty Networks
ETSI
13 ETSI GR CIM 021 V1.1.1 (2022-08)
NOTE: See IEEE 802.15™ [i.35] Working Group WSN.
ZIP Zone Improvement Plan
XML Extensible Markup Language
4 Existing Relevant Semantic Models
4.1 Classification of Data Models
There are a lot of different technologies used to define and maintain data models (OWL, SKOS, RDFS, etc.). The way
to map each type of data model in NGSI-LD may differ depending on the structure of the data model itself. In the
present document, the following data models have been analysed:
• JSON-Schema:
- SmartDataModels Program
• OWL:
- SAREF family
- GeoSPARQL Ontology
- FoaF
• SKOS:
- Agrovoc
• RDF:
- DCAT
- WoT
NOTE: Informative references to all these data models can be found in the following detailed clauses.
4.2 SAREF Family
4.2.1 SAREF Core
SAREF (ETSI TS 103 264 [i.1]) and its eleven derived extensions in different domains aims at facilitating the matching
of existing assets (standards/protocols/data models/etc.) in smart applications. They are created and maintained by the
ETSI TC SmartM2M. The starting point of SAREF is the concept of a device (e.g. a switch). The SAREF ontology
offers lists of basic functions that can be eventually combined in order to have more complex functions in a single
device. Each function has some associated commands, which can also be picked up as building blocks from a list.
Depending on the functions it accomplishes, a device can be found in some corresponding states that are also listed as
building blocks. When connected to a network, a device offers a service, which is the representation of a function which
allows by other devices in the network to discover the function, register to it and control it remotely. A service can
represent one or more functions and it is offered to any device that needs a certain set of functions. A device in the
SAREF ontology is also characterized by a profile that can be used to optimize some property, such as Energy, in a
home or office that is part of a building. Thus, the elements depicted by the ontology can be represented in NGSI-LD as
Properties of Entities, and the connection between the different elements as Relationships. Additionally, SAREF core
also describes the measurement element that relates the Device class to the SAREF Property and allows the storage of
the values measured by the device.
Most relevant ones are depicted in next paragraphs including the ones for Smart Cities, Energy, Water management,
and Health and ageing-well. The Smart Applications REFerence ontology (SAREF) is developed for interoperability
between solutions from different providers and among various activity sectors for the Internet of Things (IoT) domain.
In this clause, SAREF core and extension ontologies are described.
ETSI
14 ETSI GR CIM 021 V1.1.1 (2022-08)
The core ontology defined within the SAREF core is shown in Figure 4.2.1-1.

Figure 4.2.1-1: An overview of the SAREF core ontology
SAREF is designed as a domain-independent ontology for IoT applications. Thus, SAREF core ontology is designed as
a set of simple core ontology patterns, including definitions for general fields. The SAREF core ontology is defined as
device-centric including essential classes for IoT devices such as saref:Device, saref:Function, saref:Task, etc. This
core ontology can be used with any real device, which is a tangible object designed to accomplish a particular task in
households, common public buildings, or offices such as light switches, temperature sensors, and energy meters.
4.2.2 SAREF Extensions
4.2.2.1 Introduction
SAREF extensions are domain specific applications of the SAREF ontology identifying specific elements of the
domains. Here is the list of extensions available in June 2022.
4.2.2.2 SAREF4CITY
SAREF4CITY (ETSI TS 103 410-4 [i.2]) focuses on extending SAREF in order to create a common core of general
concepts for Smart City data-oriented IoT applications. SAREF4CITY has defined the classes for city management
such as s4city:AdministrativeArea, s4city:City, and s4city:Facility that can be used for city stakeholders or various city
services. SAREF4CITY is in its version 1.1.2.
4.2.2.3 SAREF4ENER
SAREF4ENER (ETSI TS 103 410-1 [i.3]) is the extension of SAREF for the energy domain that can be enabled to
interconnect facilities (e.g. Italy-based and Germany-based industry associations). Classes and relationships included in
SAREF4ENER can express all the powers and states of energy-related devices such as s4ener:PowerSequence,
s4ener:Energy, and s4ener:EnergyExpected. SAREF4ENER is in its version 1.1.2.
4.2.2.4 SAREF4WATR
SAREF4WATR (ETSI TS 103 410-10 [i.4]) is an extension for the water domain which is based on a limited set of use
cases and from available existing data models. SAREF4WATR has been developed in the context of the STF 566 which
was established with the goal to create SAREF extensions. The water meter can be depicted as an example of extension
uses. It can be described by a set of static classes and properties either reused from SAREF or from SAREF4WATR
such as saref:Measurement and s4watr:WaterMeter. SAREF4WATR is in its version 1.1.1.
ETSI
15 ETSI GR CIM 021 V1.1.1 (2022-08)
4.2.2.5 SAREF4EHAW
SAREF4EHAW (ETSI TS 103 410-8 [i.5]) extension has been specified and formalized by investigating EHAW
(eHEALTH and Ageing-Well) domain related resources, as reported in ETSI TR 103 509 [i.6]. Therefore,
SAREF4EHAW modular ontology has to allow the implementation of a limited set of typical EHAW related use cases,
i.e.:
• Use case 1: "monitoring and support of healthy lifestyles for citizens".
• Use case 2: "Early Warning System (EWS) and Cardiovascular Accidents detection".
SAREF4EHAW mainly reuses the following existing ontologies: SAREF, SmartBAN, SAREF4ENVI, SAREF4WEAR
and SAREF4health ontology which is a very first try to somehow extend SAREF ontology for the health vertical.
SAREF4EHAW extension, specified and formalized as reported in ETSI TR 103 509 [i.6]. SAREF4EHAW is in its
version 1.1.1.
4.2.2.6 SAREF4BLDG
SAREF4BLDG (ETSI TS 103 410-3 [i.7]), an extension of the SAREF ontology that was created based on the Industry
Foundation Classes (IFC) standard for building information. It should be noted that not the whole standard has been
transformed since it exceeds the scope of this extension, which is limited to devices and appliances within the building
domain.
SAREF4BLDG is an OWL-DL ontology that extends SAREF with 72 classes (67 defined in SAREF4EBLDG and 5
reused from the SAREF and geo ontologies), 179 object properties (177 defined in SAREF4EBLDG and 2 reused from
the SAREF and geo ontologies), and 83 data type properties (82 defined in SAREF4EBLDG and 1 reused from the
SAREF ontology). SAREF4BLDG is in its version 1.1.2.
4.2.2.7 SAREF4INMA
SAREF4INMA (ETSI TS 103 410-5 [i.8]) is an extension of SAREF that was created for the industry and
manufacturing domain. SAREF4INMA was created to be aligned with related initiatives in the smart industry and
manufacturing domain in terms of modelling and standardization, such as the Reference Architecture Model for
Industry 4.0 (RAMI), which combines several standards used by the various national initiatives in Europe that support
digitalization in the manufacturing. These initiatives include but are not limited to, the platform Industrie 4.0 Germany,
the Smart Industry initiative in the
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