ISO/IEC 21823-3:2021

Internet of Things (IoT) - Interoperability for IoT systems - Part 3: Semantic interoperability

ISO/IEC 21823-3:2021 provides the basic concepts for IoT systems semantic interoperability, as described in the facet model of ISO/IEC 21823-1, including:
– requirements of the core ontologies for semantic interoperability;
– best practices and guidance on how to use ontologies and to develop domain-specific applications, including the need to allow for extensibility and connection to external ontologies;
– cross-domain specification and formalization of ontologies to provide harmonized utilization of existing ontologies;
– relevant IoT ontologies along with comparative study of the characteristics and approaches in terms of modularity, extensibility, reusability, scalability, interoperability with upper ontologies, and so on, and;
– use cases and service scenarios that exhibit necessities and requirements of semantic interoperability.

General Information

• Status: Published
• Publication Date: 20-Sep-2021
• ICS: 35.020 - Information technology (IT) in general
• ICS: 35.110 - Networking
• Technical Committee: SC 41 - Internet of Things and Digital Twin
• Current Stage: PPUB - Publication issued
• Completion Date: 21-Sep-2021

Standards Content (sample)

ISO/IEC 21823-3
Edition 1.0 2021-09
INTERNATIONAL
STANDARD
colour
inside
Internet of Things (IoT) – Interoperability for IoT systems –
Part 3: Semantic interoperability
ISO/IEC 21823-3:2021-09(en)
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ISO/IEC 21823-3
Edition 1.0 2021-09
INTERNATIONAL
STANDARD
colour
inside
Internet of Things (IoT) – Interoperability for IoT systems –
Part 3: Semantic interoperability
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.020; 35.110 ISBN 978-2-8322-1019-4

Warning! Make sure that you obtained this publication from an authorized distributor.

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– 2 – ISO/IEC 21823-3:2021 © ISO/IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 8

4 Abbreviated terms ........................................................................................................... 9

5 IoT semantic interoperability process ............................................................................... 9

5.1 Overview................................................................................................................. 9

5.2 IoT semantic interoperability process requirements ............................................... 10

5.3 IoT semantic interoperability models ..................................................................... 11

5.4 IoT semantic interoperability guidelines ................................................................ 13

5.4.1 Guidelines on the capture of semantic meaning ............................................. 13

5.4.2 Guidelines on the integration of semantic interoperability capability ............... 14

5.4.3 Guidelines on the support of semantic interoperability engineering ................ 15

6 IoT semantic interoperability life cycle ........................................................................... 19

6.1 Life cycle requirements ......................................................................................... 19

6.2 Life cycle model .................................................................................................... 22

6.3 Life cycle implementation guidelines ..................................................................... 23

6.3.1 Guidelines on ontology life cycle .................................................................... 23

6.3.2 Guidelines on semantic interoperability life cycle ........................................... 23

6.3.3 Guidelines on IoT system life cycle ................................................................ 24

Annex A (informative) Guidance on how to learn IoT semantic interoperability ..................... 26

Annex B (informative) Guidance on how to develop IoT semantic interoperability................. 29

B.1 Developing semantic interoperability capabilities .................................................. 29

B.2 Building steps ....................................................................................................... 29

Annex C (informative) Guidance on how to manage IoT semantic interoperability life

cycle ..................................................................................................................................... 31

C.1 Interoperability specification life cycle that supports ontologies ............................. 31

C.2 IoT system life cycle supporting interoperability .................................................... 32

Annex D (informative) Ontological specification of the IoT Reference Architecture ............... 33

D.1 General ................................................................................................................. 33

D.2 Service, network, IoT device and IoT gateway ...................................................... 33

D.3 IoT-User ............................................................................................................... 34

D.4 Virtual entity, physical entity and IoT device.......................................................... 35

D.5 Domain-based Reference Model (RM)................................................................... 35

Annex E (informative) Related existing ontologies ............................................................... 37

E.1 W3C Semantic Sensor Network ontology .............................................................. 37

E.2 IoT-Lite ................................................................................................................. 37

E.3 Open Connectivity Foundation (OCF) ontology ..................................................... 37

E.4 ETSI Smart Applications REFerence ontology ....................................................... 41

E.5 oneM2M Base Ontology ........................................................................................ 42

E.6 Sensor Model Language (SensorML) .................................................................... 42

E.7 IoT-O .................................................................................................................... 43

E.8 IoT ontology unification approach ......................................................................... 43

Bibliography .......................................................................................................................... 45

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ISO/IEC 21823-3:2021 © ISO/IEC 2021 – 3 –

Figure 1 – Semantic interoperability facet for IoT .................................................................... 5

Figure 2 – Using metadata in semantic interoperability ........................................................... 6

Figure 3 – Meaningfulness of the data, described with metadata ............................................. 6

Figure 4 – Objective of semantic interoperability standard ...................................................... 9

Figure 5 – IoT semantic interoperability process model ......................................................... 11

Figure 6 – Semantic information usage model ....................................................................... 12

Figure 7 – Example of structured knowledge representation ................................................. 13

Figure 8 – Example of semantic information usage for a temperature sensor ........................ 15

Figure 9 – Example of ontology mapping .............................................................................. 17

Figure 10 – Example of ontology alignment ........................................................................... 18

Figure 11 – Example of ontology merging ............................................................................. 18

Figure 12 – Example of ontology integration ......................................................................... 19

Figure 13 – Example of modular design ................................................................................ 22

Figure 14 – Example of interoperability maturity evaluation result ......................................... 22

Figure 15 – Semantic interoperability life cycle model ........................................................... 23

Figure 16 – Example of ontology life cycle model .................................................................. 23

Figure 17 – Example of interoperability specification life cycle .............................................. 24

Figure D.1 – IoT entity .......................................................................................................... 33

Figure D.2 – Service, network, IoT device and IoT gateway .................................................. 34

Figure D.3 – IoT-User ........................................................................................................... 34

Figure D.4 – Virtual entity, physical entity, and IoT device .................................................... 35

Figure D.5 – Domain-based Reference Model ....................................................................... 36

Figure E.1 – Architecture – concepts .................................................................................... 38

Figure E.2 – Communication layering model ......................................................................... 38

Figure E.3 – oneIoTa ............................................................................................................ 39

Figure E.4 – OCF ontology ................................................................................................... 40

Figure E.5 – SAREF and its extensions ................................................................................ 41

Figure E.6 – Overview of the SAREF ontology ...................................................................... 42

Table 1 – IoT semantic interoperability process requirements ............................................... 10

Table 2 – Llife cycle requirements ......................................................................................... 20

Table A.1 – Syllabus example on IoT semantic interoperability practice ................................ 26

Table A.2 – Course content for semantic interoperability practice ......................................... 27

Table B.1 – Building steps for IoT semantic interoperability .................................................. 30

Table C.1 – Example of interoperability specification life cycle .............................................. 31

Table C.2 – Example of IoT system life cycle ........................................................................ 32

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– 4 – ISO/IEC 21823-3:2021 © ISO/IEC 2021
INTERNET OF THINGS (IoT) –
INTEROPERABILITY FOR IoT SYSTEMS –
Part 3: Semantic interoperability
FOREWORD

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ISO/IEC 21823-3 has been prepared by subcommittee 41: Internet of Things and related

technologies, of ISO/IEC joint technical committee 1: Information technology. It is an

International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
JTC1-SC41/233/FDIS JTC1-SC41/244/RVD

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2,
and developed in accordance with ISO/IEC Directives, Part 1, available at:
www.iec.ch/members_experts/refdocs and www.iso.org/directives.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it

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ISO/IEC 21823-3:2021 © ISO/IEC 2021 – 5 –
INTRODUCTION

The use of the Internet of Things (IoT) is increasing every year, in application areas such as

manufacturing, healthcare, and new cross-domain applications related to smart cities (e.g.

water, energy, transport, or health). Most IoT systems want to share information, which can be

done by interoperability. Mechanisms are therefore needed on how to exchange information

and use associated data and data description.

IoT interoperability is described as a successful interaction among entities specified in

ISO/IEC 30141 [1] , for instance between IoT services provided by different IoT service

providers. It can be achieved using the interoperability facet model defined in ISO/IEC 21823‑1,

which defines five facets: transport, syntactic, semantic, behavioural and policy interoperability.

IoT semantic interoperability is the facet which enables the exchange of data between IoT

systems using understood data information models (or semantic meanings). According to a

recently published white paper [2]:

"Semantic interoperability is achieved when interacting systems attribute the same meaning

to an exchanged piece of data, ensuring consistency of the data across systems regardless

of individual data format. This consistency of meaning can be derived from pre-existing

standards or agreements on the format and meaning of data or it can be derived in a dynamic

way using shared vocabularies either in a schema form and/or in an ontology-driven

approach."
As shown in Figure 1,

– semantic interoperability means that information in different data information models can be

translated into understandable meaning and exchanged between applications;

– semantic interoperability provides the capability for applications to understand exchanged

information;

– semantic interoperability for IoT is achieved by invoking services, and by using specific

knowledge and concepts of IoT.
Figure 1 – Semantic interoperability facet for IoT

Semantic interoperability is achieved through the use of metadata, or descriptions of data. The

approach of providing data and descriptions has been widely used in IT systems. Two examples

are:
a) conceptual schemas have been used to describe database content;
b) record layouts have been used to display the content of a database record.

As shown in Figure 2, many services invoked by semantic interoperability involve metadata,

thus enabling their discovery, understanding and (re)usability.
___________
Numbers in square brackets refer to the Bibliography.
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– 6 – ISO/IEC 21823-3:2021 © ISO/IEC 2021
Figure 2 – Using metadata in semantic interoperability

Metadata provides IoT systems with a common understanding of exchanged data. Figure 3

shows how the meaning of data is defined by the metadata to a specific room temperature (left

column) and how it is described with metadata (right column).
Figure 3 – Meaningfulness of the data, described with metadata

Knowledge that metadata represents can be described using ontologies. In other words,

semantic interoperability needs shared, unambiguous, machine-understandable metadata, to

be able to perform exchange of information using metadata. The application of semantics in IoT

has still been limited because most metadata are developed independently, making it difficult

for IoT entities or applications to interoperate semantically. In this document, an ontology-driven

approach for semantic interoperability is specified to design and specify metadata, so that the

sensors, devices, systems and services can express metadata information and data by applying

the ontologies to achieve semantic interoperability. Stakeholders targeted by this document

include ontology engineers and IoT system engineers who are building semantic interoperability

capabilities for IoT systems.

This document also specifies methods and techniques to build semantic interoperability for IoT

systems. Clause 5 focuses on the IoT semantic interoperability process. Clause 6 focuses on

the IoT semantic interoperability life cycle management.
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ISO/IEC 21823-3:2021 © ISO/IEC 2021 – 7 –

Informative annexes provide additional information and guidance. Annex A, Annex B and

Annex C provide guidance on how to learn IoT semantic interoperability, develop IoT semantic

interoperability, and manage IoT semantic interoperability life cycle, respectively. Annex D

provides ontological specification of the IoT Reference Architecture specified in

ISO/IEC 30141 [1]. Annex E provides related existing ontologies that are applicable for IoT

semantic interoperability.
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– 8 – ISO/IEC 21823-3:2021 © ISO/IEC 2021
INTERNET OF THINGS (IoT) –
INTEROPERABILITY FOR IoT SYSTEMS –
Part 3: Semantic interoperability
1 Scope

This document provides the basic concepts for IoT systems semantic interoperability, as

described in the facet model of ISO/IEC 21823 -1, including:
– requirements of the core ontologies for semantic interoperability;

– best practices and guidance on how to use ontologies and to develop domain-specific

applications, including the need to allow for extensibility and connection to external

ontologies;

– cross-domain specification and formalization of ontologies to provide harmonized utilization

of existing ontologies;

– relevant IoT ontologies along with comparative study of the characteristics and approaches

in terms of modularity, extensibility, reusability, scalability, interoperability with upper

ontologies, and so on;

– use cases and service scenarios that exhibit necessities and requirements of semantic

interoperability.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies.

For undated references, the latest edition of the referenced document (including any

amendments) applies.
ISO/IEC 20924, Internet of Things (IoT) – Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO/IEC 20924 and the

following apply. ISO and IEC maintain terminological databases for use in standardization at

the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
semantic interoperability

interoperability so that the meaning of the data model within the context of a subject area is

understood by the participating systems

[SOURCE: ISO/IEC 19941:2017, 3.1.5, modified – In the term, "data" has been deleted.]

3.2
metadata
data that defines and describes other data
[SOURCE: ISO/IEC 11179-3:2013, 3.2.74]
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ISO/IEC 21823-3:2021 © ISO/IEC 2021 – 9 –
3.3
ontology

specification of concrete or abstract things, and the relationships among them, in a prescribed

domain of knowledge
Note 1 to entry: The specification should be computer processable.
[SOURCE: ISO/IEC 19763-3:2020, 3.1.1.1]
4 Abbreviated terms
ICT information and communication technology
IoT Internet of Things
PKI public key infrastructure
5 IoT semantic interoperability process
5.1 Overview

IoT semantic interoperability enables the exchange of data between IoT systems using

understood data information models (or semantic meanings). Such models are based on

ontologies, which are processable specifications of concepts and relations concerning IoT

systems. The benefit of IoT semantic interoperability is to contribute to meet interoperability,

reusability, scalability or trustworthiness properties. IoT semantic interoperability has the

following stakeholders and concerns:
a) ontology engineers, who focus on ontology development in a concern;

b) IoT system engineers, who focus on IoT system development and integration of semantic

interoperability capabilities in a concern.

As shown in Figure 4, this document provides ontology engineers and IoT system engineers

with requirements and specification of methods to prepare and build semantic interoperability.

Figure 4 – Objective of semantic interoperability standard
Two types of requirements are identified:

1) IoT semantic interoperability requirements, which focus on how to create data information

models, how to develop and integrate interpretation capability in IoT systems;

2) life cycle requirements, which focus on the management of data information model

perimeters, of data information model design, and of data information model maintenance.

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– 10 – ISO/IEC 21823-3:2021 © ISO/IEC 2021
5.2 IoT semantic interoperability process requirements

The following processes shall be carried out by IoT system engineers and ontology engineers:

– data information model creation;
– semantic interoperability capability integration;
– semantic interoperability engineering support.

Table 1 provides for each process a list of requirements with a rationale and a resulting work

product that can be used as evidence for conformance.
Table 1 – IoT semantic interoperability process requirements
Resulting work
Processes Requirements Rationale
product
Data information
model based on the
Capture common IoT systems rely on common architecture,
gathered and
knowledge using capabilities and communication means, e.g.
documented
common ontologies IoT sensors, actuators, gateways, devices.
common knowledge
on the IoT system
Data
Capture domain- Domain specific
information
specific knowledge IoT systems can focus on specific domains data information
model creation
using domain such as transport, energy, health. model on the IoT
ontologies system
Capture cross- IoT systems can cover cross-domains. For Cross-domain
domain knowledge instance, an electric-mobility IoT system specific data
using cross-domain belongs to the transport and the energy information model
ontologies domain. on the IoT system
IoT systems can use various interoperability
parameters including technical parameters
(e.g. drivers, protocols) and semantic
parameters (e.g. application capabilities).
Develop an IoT IoT system
Exchange of such parameters can take place
system capability to capability to
using metadata prior to device nominal
exchange exchange
operation. Metadata can be exposed in the
information about IoT information on IoT
form of schema or subschema or by OWL/XML
device device
or JSON-LD.
interoperability interoperability
The exchange can involve a proxy when an
IoT device cannot provide the capability
directly.
IoT systems can use multiple knowledge
Semantic
representations. Agreement is needed on the
interoperability
representation to be used for information
capability
exchange. Negotiation is needed to agree on
Develop an IoT IoT system
integration
the level of semantic knowledge that is at
system capability to capability to
stake, e.g. using representations of
negotiate negotiate
parameters and agreeing on interoperability
interoperability interoperability
profiles.
profiles profiles
The negotiation can involve a proxy when an
IoT device cannot provide the capability
directly.
IoT systems integrate multiple technologies to
Validate and
enable interoperability (e.g. drivers, protocols, IoT device providing
integrate the various
middleware) corresponding to different overall
capabilities to enable
interoperability facets. They also integrate interoperability
IoT device
multiple operations (e.g. discovery, capability
interoperability
negotiation) to enable interoperability.
Semantic Provide and apply
Engineers need supporting tools such as Selection of tools to
interoperability tools to achieve
ontology discovery and selection, mapping, achieve semantic
engineering semantic
alignment, merging and integration. interoperability
support interoperability
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ISO/IEC 21823-3:2021 © ISO/IEC 2021 – 11 –
5.3 IoT semantic interoperability models

IoT semantic interoperability can be described with two models: a process model and a usage

model. The process model focuses on how semantic interoperability capability is created. The

usage model focuses on how semantic information is used and exchanged.

Figure 5 provides the process model for IoT semantic interoperability. It is based on the

assumption that interoperability knowledge is made available in processable forms such as the

knowledge graph, constructed through ontologies. The entities in Figure 5 will be further

described in 5.4.1.
Figure 5 – IoT semantic interoperability process model
IoT semantic interoperability involves the
...