ISO/IEC 21823-4:2022

Internet of things (IoT) — Interoperability for IoT systems — Part 4: Syntactic interoperability

ISO/IEC 21823-4:2022 specifies the IoT interoperability from a syntactic point of view. In ISO/IEC 21823-1: Framework [2], five facets are described for IoT interoperability, i.e. transport, semantic, syntactic, behavioural and policy. In this document, the following specifications for IoT interoperability from syntactic viewpoint are included; – A principle of how to achieve syntactic interoperability among IoT systems which include IoT devices – Requirements on information related to IoT devices for syntactic interoperability – A framework for processes on developing information exchange rules related to IoT devices from the syntactic viewpoint

Titre manque — Partie 4: Titre manque

General Information

• Status: Published
• Publication Date: 10-Mar-2022
• ICS: 35.020 - Information technology (IT) in general
• Technical Committee: ISO/IEC JTC 1/SC 41 - Internet of things and digital twin
• Drafting Committee: ISO/IEC JTC 1/SC 41 - Internet of things and digital twin
• Current Stage: 6060 - International Standard published
• Start Date: 11-Mar-2022
• Due Date: 09-Sep-2023
• Completion Date: 11-Mar-2022

Standards Content (Sample)

ISO/IEC 21823-4
Edition 1.0 2022-03
INTERNATIONAL
STANDARD

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inside
Internet of things (IoT) – Interoperability for IoT systems –
Part 4: Syntactic interoperability


ISO/IEC 21823-4:2022-03(en)

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ISO/IEC 21823-4


Edition 1.0 2022-03




INTERNATIONAL



STANDARD








colour

inside










Internet of things (IoT) – Interoperability for IoT systems –

Part 4: Syntactic interoperability


























INTERNATIONAL

ELECTROTECHNICAL

COMMISSION






ICS 33.020 ISBN 978-2-8322-1083-4




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

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CONTENTS
FOREWORD . 4
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Abbreviated terms . 7
5 Principle for IoT syntactic interoperability . 7
5.1 General . 7
5.2 Principle for IoT syntactic interoperability . 7
5.3 Relevant technologies for syntactic interoperability . 8
5.3.1 Metamodel and syntactic interoperability . 8
5.3.2 Metamodel-driven approaches supporting interoperability issues . 9
5.4 The overall structure of the proposed approach . 9
5.5 The methodology of metamodel-driven information exchange . 10
5.6 Information exchange rules . 11
5.6.1 Categories of information exchange rules . 11
5.6.2 Information exchange rules expression . 12
5.6.3 Information exchange rules expression example . 12
6 Requirements on information related to IoT devices . 12
6.1 General . 12
6.2 General requirements on the translation rules . 13
6.2.1 General . 13
6.2.2 Required intrinsic properties of physical IoT devices (IPIoT) . 13
6.2.3 Required extrinsic properties of physical IoT devices (EPIoT) . 14
6.3 General requirements on the operation rules . 15
6.3.1 Overview of mismatches between IoT systems . 15
6.3.2 Required properties and syntactic resolutions for potential IoT
mismatches . 17
6.3.3 Details of required properties and syntactic resolutions for potential IoT
mismatches . 18
7 A framework for IoT syntactic interoperability . 30
7.1 General . 30
7.2 A conceptual model for dataset of operation rules (DOR) . 31
7.3 Detailed procedures for a syntactic interoperability framework . 31
7.3.1 Procedure A to prepare the required properties and resolutions . 31
7.3.2 Procedure B to create information exchange rules (DIER) . 32
7.3.3 Procedure C to execute the information exchange rules and check the
result . 32
Annex A (informative) Properties for physical IoT devices and data . 33
A.1 Intrinsic properties of physical IoT devices . 33
A.2 Extrinsic properties of physical IoT devices . 35
Annex B (informative) A use case . 37
B.1 General . 37
B.2 The use case overview: Connected car and vehicle in smart city . 37
B.3 A scenario of this use case . 38
B.3.1 The architecture of this use case . 38

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ISO/IEC 21823-4:2022 © ISO/IEC 2022 – 3 –
B.3.2 Scenario: Data exchange between a connected car and a traffic
management system (TMS) . 38
B.4 Examples used in this use case . 39
B.4.1 General . 39
B.4.2 Illustrated example files and their relationships . 40
Annex C (informative) Other metamodel definitions . 41
Bibliography . 42

Figure 1 – The overall structure of the proposed approach . 9
Figure 2 – Model hierarchies and metamodel-driven information exchange rules . 10
Figure 3 – Categories of information exchange rules . 11
Figure 4 – Excerpted information exchange rules for Annex B . 12
Figure 5 – Classifications of requirements on information related to IoT devices . 13
Figure 6 – A procedure for mismatch detection and resolution . 16
Figure 7 – An example of mismatch detection and resolution . 17
Figure 8 – A framework for processes on developing information exchange rules
related to IoT devices from the syntactic viewpoint . 30
Figure 9 – An excerpted conceptual model of DOR (dataset of operation rules) . 31
Figure 10 – Steps of Procedure A . 32
Figure B.1 – Overall view of use case 1 . 37
Figure B.2 – Architecture of connected car and vehicle in smart city use case . 38
Figure B.3 – Information exchange between a car and a TMS . 38
Figure B.4 – Relationships of example files for this use case . 40

Table 1 – Required intrinsic properties of physical IoT devices . 14
Table 2 – Required extrinsic properties of physical IoT devices . 15
Table 3 – Required properties and resolutions for potential IoT mismatches . 18
Table 4 – Mismatch1: Synchronization mismatch . 19
Table 5 – Mismatch2: Sampling frequency mismatch . 20
Table 6 – Mismatch3: Location mismatch . 21
Table 7 – Mismatch4: Data recording pattern mismatch . 22
Table 8 – Mismatch5: Precision mismatch. 23
Table 9 – Mismatch6: Significant figure mismatch . 24
Table 10 – Mismatch7:Range mismatch . 25
Table 11 – Mismatch8: Calibration mismatch . 26
Table 12 – Mismatch9: Response time mismatch . 27
Table 13 – Mismatch10: Acquisition status mismatch . 28
Table 14 – Mismatch11: Unit mismatch . 29
Table A.1 – Intrinsic properties of physical IoT devices . 33
Table A.2 – Extrinsic properties of physical IoT devices . 36
Table C.1 – Definitions of metamodel in various resources . 41

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INTERNET OF THINGS (IoT) –
INTEROPERABILITY FOR IoT SYSTEMS –

Part 4: Syntactic interoperability


FOREWORD
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ISO/IEC 21823-4 has been prepared by subcommittee 41: Internet of Things and Digital Twin,
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-SC41/255/FDIS JTC1-SC41/269/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
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ISO/IEC 21823-4:2022 © ISO/IEC 2022 – 5 –
INTRODUCTION
In the world of the Internet of Things (IoT), heterogeneous systems and devices need to be
connected and exchange data with others. How data exchange can be implemented becomes
a key issue of interoperability among IoT industries. Information models (IMs), which can well
represent specifications of data, are adopted and utilized to solve the interoperability problem.
Meanwhile, as systems and devices in IoT can have different information models with different
modelling methodologies and formats, interoperability based on different information models is
recognized as an urgent problem. The IoT interoperability related systems and applications
1
have an 11 trillion market potentially [1] .
The ISO/IEC 21823 series standards address issues that relate to interoperability both between
different IoT systems and within a single IoT system. ISO/IEC 21823-1 [2] describes a general
framework for interoperability for IoT systems. It includes a five facet model for interoperability
that includes transport, syntactic, semantic, behavioural, and policy viewpoints.
Different parts of ISO/IEC 21823, based on one of the facets, provide specifications from their
corresponding viewpoints. Each of the parts can refer to others but is independent. Currently,
ISO/IEC 21823-2 [3] defines specifications from the transport viewpoint, ISO/IEC 21823-3 [4]
defines requirements, provides guidance, etc. from the semantic viewpoint, and
ISO/IEC 21823-4 specifies the syntactic interoperability.
Syntactic interoperability means that exchanged information can be understood by the
participating IoT systems which contain IoT devices. In more detail, the syntactic interoperability
is related to the information models' representing formats, structures, and grammar of their
modelling languages such as a length of a data string, constraints on data types, and forbidden
characters.
This document first provides the principle of how to achieve syntactic interoperability based on
metamodel-driven approaches. In other words, the reason why the information exchange rules
based on metamodels can support syntactic interoperability among different IoT systems will
be elaborated. Secondly, requirements on information models such as metamodels and models
of IoT systems including IoT devices are described. Features related to IoT devices such as the
identifier, device type, setup environments, and functions need to be considered to accomplish
syntactic interoperability among different information models utilized in IoT systems. Thirdly, a
framework for processes on developing information exchange rules related to IoT devices from
the syntactic viewpoint is provided. For example, the kinds of metamodels, and the types of
entities and relationships that shall be selected are specified, and the procedure of how to build
the information exchange rules from different information models is provided.
In Annex A, possible intrinsic and extrinsic properties of IoT devices are listed as additional
information of Clause 6. In Annex B, a use case of how the syntactic interoperability in
accordance with specifications in this document among industrial IoT systems and IoT devices
is described.
With this document, system and device vendors, who need to improve and/or develop their
products to comply with IoT requirements, can implement specifications of this document to
their products for an automatic or semi-automatic realization of IoT syntactic interoperability.


_____________
1
 Numbers in square brackets refer to the Bibliography.

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INTERNET OF THINGS (IoT) –
INTEROPERABILITY FOR IoT SYSTEMS –

Part 4: Syntactic interoperability



1 Scope
This part of ISO/IEC 21823 specifies the IoT interoperability from a syntactic point of view. In
this document, the following specifications for IoT interoperability from a syntactic viewpoint are
included:
– a principle of how to achieve syntactic interoperability among IoT systems which include IoT
devices;
– requirements on information related to IoT devices for syntactic interoperability;
– a framework for processes on developing information exchange rules related to IoT devices
from the syntactic viewpoint.
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 web
addresses:
• ISO Online browsing platform: available at http://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1
instance
individual entity having its own value and possibly its own identity
[SOURCE: ISO 19103:2015 [5], 4.20]
3.2
metamodel
special kind of model that specifies the abstract syntax of a modelling language
Note 1 to entry: A model is an instance (3.1) of a metamodel
Note 2 to entry: IoT syntactic interoperability is achieved by information exchange rules through the structure, data
format, and syntactic constraints using syntactic aspects of the metamodel.

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ISO/IEC 21823-4:2022 © ISO/IEC 2022 – 7 –
[SOURCE: ISO/IEC 19506:2012 [6], modified – The description that follows the definition has
been deleted. Notes to entry have been added.]
3.3
model
abstraction of some aspects of reality
[SOURCE: ISO 19109:2015 [7], 4.15]
3.4
property
particular characteristic of an object type
[SOURCE: ISO 16484-5:2017 [8], 3.2.74]
3.5
syntactic interoperability
interoperability such that the formats of the exchanged information can be understood by the
participating systems
Note 1 to entry: System means IoT system.
Note 2 to entry: IoT device, IoT gateway, sensor and actuator are considered as system.
[SOURCE: ISO/IEC 19941:2017 [9], 3.1.4, modified – Notes to entry have been added.]
4 Abbreviated terms
CRS coordinate reference system
EPIoT extrinsic properties of physical IoT devices
IPIoT intrinsic properties of physical IoT devices
IoT Internet of Things
JSON JavaScript Object Notation
MOF Meta Object Facility
UML Unified Modelling Language
XML extensible markup language
5 Principle for IoT syntactic interoperability
5.1 General
In the ISO/IEC 21823 series, ISO/IEC 21823-1 [2] defines an overall framework for IoT
interoperability. It specifies that IoT interoperability shall be supported by standards from five
facets: transport, semantic, syntactic, behavioural, and policy. A standard based on each of the
facets shall provide specifications from its corresponding viewpoint. Each of the standards can
refer to or can be independent of standards based on other facets. ISO/IEC 21823-2 [3] defines
specifications from the transport viewpoint. ISO/IEC 21823‑3 [4] defines requirements, provides
guidance, etc. from the semantic aspect. ISO/IEC 21823-4 (this document) addresses the
syntactic interoperability that provides specifications from the syntax viewpoint.
5.2 Principle for IoT syntactic interoperability
In this subclause, a principle for IoT syntactic interoperability is specified. In order for an IoT
system to achieve syntactic interoperability with other IoT systems and devices, the information
exchange rules between their data are adopted.

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The information exchange rules for syntactic interoperability provide the following types of
information exchange.
a) Format exchange.
– The term "format" is bound for a data format.
– The "format exchange" means that information in different data formats can be
exchanged.
For example, data in the UML format can be exchanged with data in the XML format.
b) Structure exchange.
– The term "structure" is bound for a data structure that has a hierarchy and branches.
– The "structure exchange" means that information in different structures can be
exchanged.
For example, information defined in a hierarchical tree structure can be transformed into a
flat tree structure.
c) Syntactic constraint exchange.
– The term "constraint" is a condition related to syntax or syntactic requirements on data.
– The "syntactic constraint exchange" means that information with different constraints
can be exchanged.
For example, data in IoT System1 have a value of one digit after the decimal point, and data
in IoT System2 have a value of two digits after the decimal point. Their data accuracy
exchange is classified into syntactic constraint exchange.
Furthermore, information of IoT systems is expressed with models. In each IoT system, its
information can be represented with a metamodel, models, and instances [10]. In order to
describe information exchange rules between IoT systems for their syntactic interoperability,
syntactic aspects in their metamodels and models are utilized. In addition, specific requirements
for metamodels, models, and information exchanges in the IoT domain are included in this
document.
5.3 Relevant technologies for syntactic interoperability
5.3.1 Metamodel and syntactic interoperability
A metamodel, as the model's model, consists of statements about models. Especially in the
UML as described in [10], the metamodel specifies the abstract syntax of the UML. The abstract
syntax defines the set of UML modelling concepts, attributes, relationships as well as rules for
combining concepts to construct partial UML models.
There are also other definitions for metamodel in ISO/IEC and IEEE standards. Some of them
are listed in Table C.1 in Annex C. Several metamodel definitions in different resources are
collected in ISO/IEC/IEEE 24765:2017 [11]. In this document, Definition 7 of metamodel in
Table C.1, i.e. "special kind of model that specifies the abstract syntax of a modelling language",
is adopted. From this definition, it is clear that an approach of creating information exchange
rules with elements available in metamodels is actually based on the syntax and therefore is
acceptable for syntactical interoperability. UML, OWL (Ontology Language), OntoML (Ontology
[12]), XML, etc. are modelling languages adopted and utilized in different
Markup Language
systems and domains.

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5.3.2 Metamodel-driven approaches supporting interoperability issues
Metamodel-driven information exchange and interoperability approaches are adopted as
holistic approaches in industry domains [13], [14] to enable a model-driven engineering
approach in the area of information integration and interoperation. By creating declarative
mapping specifications, i.e. exchange rules, automatic information exchange can be executed
at run-time and off-line among heterogeneous systems and devices. As the metamodel-driven
approaches tackle the interoperability problems at a higher abstraction level than models, it can
increase the efficiency of achieving interoperability among heterogeneous systems and devices
which comply with the same metamodel. In other words, information exchange rules can be
reused by IoT systems and IoT devices whose information models are in compliance with the
same metamodel.
5.4 The overall structure of the proposed approach

Figure 1 – The overall structure of the proposed approach
Figure 1 illustrates the overall structure of the proposed approach. Figure 1 shows two IoT
systems: IoT System1 and IoT System2. In each IoT system, its information consists of a
metamodel, model, and instance data. In order to achieve syntactic interoperability between
these two systems, the information exchange rules based on the metamodels of both IoT
systems need to be created. To create information exchange rules, their required properties
and resolutions to support executing information exchange need to be analysed and defined.
In Figure 1:
– lines starting with "#" denote comment lines;
– in the text box of "information exchange rule example", sample information for syntactic
interoperability is listed;
– in the text box of "required properties and resolutions", example properties and syntactic
resolution for mismatch are listed.
In this document, thr
...