ETSI GR CIM 022 V1.1.1 (2022-12)

Context Information Management (CIM); NGSI-LD/oneM2M interworking proxy proposal

DGR/CIM-0022

General Information

• Status: Not Published
• Technical Committee: CIM - cross-cutting Context Information Management
• Current Stage: 12 - Completion
• Due Date: 27-Dec-2022
• Completion Date: 21-Dec-2022

Standards Content (Sample)

ETSI GR CIM 022 V1.1.1 (2022-12)






GROUP REPORT
Context Information Management (CIM);
NGSI-LD/oneM2M interworking proxy proposal
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.

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2 ETSI GR CIM 022 V1.1.1 (2022-12)

Reference
DGR/CIM-0022
Keywords
interworking, IoT, NGSI-LD, oneM2M

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ETSI

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Content
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 . 7
3.1 Terms . 7
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Architecture Model. 8
4.1 Information Model . 8
4.2 Reference Model . 9
4.3 Types of Interworking Proxy Entity . 9
5 Solution 1 - labels based dynamic interworking . 10
5.1 Introduction . 10
5.2 oneM2M features . 10
5.3 Resource mapping . 11
5.4 Procedures . 12
5.4.1 Pre-configuration . 12
5.4.2 IPE initialization . 12
5.4.3 Resource synchronization . 13
6 Solution 2 - Mapping ontology based dynamic interworking . 14
6.1 Introduction . 14
6.2 oneM2M features . 14
6.2.1 Overall semantic capabilities . 14
6.2.2 semanticDescriptor resource type . 15
6.2.3 Semantic discovery and query . 15
6.2.4 Semantic discovery . 15
6.2.5 Semantic query . 15
6.3 Resource mapping . 16
6.3.1 Introduction. 16
6.3.2 Mapping ontology . 16
6.3.3 Attribute addressing . 17
6.3.4 Semantic annotation example . 17
6.3.5 Translation Guidelines . 21
6.4 Semantic Interworking Procedures . 25
6.4.1 NGSI-LD entity creation . 25
6.4.2 Resource synchronization . 26
7 Solution 3 - Annotation ontology based static interworking . 27
7.1 Introduction . 27
7.2 oneM2M features . 28
7.3 Resource mapping . 28
7.3.0 Introduction. 28
7.3.1 Resource Mapping from NGSI-LD to oneM2M . 28
7.3.2 Resource Mapping from oneM2M to NGSI-LD . 30
7.4 Procedures for Interworking from NGSI-LD to oneM2M . 33
7.4.1 Pre-configuration . 33
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7.4.2 IPE initialization . 34
7.4.3 Resource synchronization . 35
7.5 Procedures for Interworking from oneM2M to NGSI-LD . 35
7.5.1 Pre-configuration . 35
7.5.2 IPE initialization . 36
7.5.3 Resource synchronization . 37
8 Conclusions and future considerations . 37
History . 39


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5 ETSI GR CIM 022 V1.1.1 (2022-12)
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 presents ideas and state-of-the-art solutions, based on the NGSI-LD eco-system (specifically the
NGSI-LD API [i.2], information model [i.3] and security and privacy [i.4]), in the area of smart cities, i.e. the area of
software platforms which, based on real-time data flows, make it possible to better manage cities and communities.
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Introduction
The present document aims to find candidate interworking solutions between oneM2M and NGSI-LD technologies.
oneM2M is one of the most widely used middleware platform standard for IoT/M2M devices/gateways and servers.
oneM2M, as the name stands for, is the standards for communicating IoT data among IoT things and IoT applications
so oneM2M provides IoT data and things related functions such as collecting IoT data, to actuating IoT things,
managing IoT things. NGSI-LD is the standard focusing on exchanging data from data providers and consumers.
Therefore, in NGSI-LD stand point, what kind of data to be exchanged is out of scope and it does not provide any IoT
specific functions.
As stated above, two technologies have its own speciality so the present document investigates the complementary use
of the two technologies as follows:
1) NGSI-LD context broker can make use of oneM2M for actuating IoT things.
2) NGSI-LD context broker can make use of oneM2M for collecting IoT data.
3) oneM2M can make use of NGSI-LD for collecting data from external systems so oneM2M applications can
access that with oneM2M protocols.
4) oneM2M can make use of NGSI-LD for collecting linked data which can be leveraged with its semantic
features.
In the end of 2022, there are 4 versions of oneM2M standards and compliant products in the deployments. In the case of
NGSI-LD, there are release 1 compatible deployments. One important requirement for the candidate solutions in the
present document is the version compatibility of any of the oneM2M and NGSI-LD standards. Therefore, the solutions
do not propose any changes of features or APIs of both NGSI-LD and oneM2M specifications and use as-is features.
The scope of the present document is limited to data synchronization between oneM2M and NGSI-LD. Other
interworking for example querying information of NGSI-LD context broker from oneM2M system or querying
information of oneM2M system from NGSI-LD context broker is out-of-scope of the present document.
To be able to synchronize data between NGSI-LD and oneM2M, the interworking solutions relies on the oneM2M
Subscription/Notification and NGSI-LD Subscription/Notification.
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1 Scope
The present document provides several NGSI-LD/oneM2M interworking proxy solutions using existing oneM2M
features and analyses those to find which one is suitable for a certain condition.
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
non-specific. 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 118 101: "oneM2M; Functional Architecture (oneM2M TS-0001)".
[i.2] ETSI GS CIM 009 (V1.6.1): "cross-cutting Context Information Management (CIM); NGSI-LD
API".
NOTE 1: The interworking scheme uses the NGSI-LD ontology (e.g. ngsi-ld:Entity) in ETSI GS CIM 009.
NOTE 2: Available at
https://www.etsi.org/deliver/etsi_gs/CIM/001_099/009/01.06.01_60/gs_CIM009v010601p.pdf.
[i.3] FED4IoT project.
NOTE 2: Available at https://fed4iot.org/.
[i.4] ETSI TS 118 123 (V3.7.3): "oneM2M; Home Appliances Information Model and Mapping
(oneM2M TS-0023 version 3.7.3 Release 3)".
[i.5] ETSI TS 118 104: "oneM2M; Service Layer Core Protocol Specification (oneM2M TS-0004)".
[i.6] oneM2M TR-0007 (V2.11.1): "Study of Abstraction and Semantics Enablements".
[i.7] Smart Data Models About Web Page.
NOTE: Available at: https://smartdatamodels.org/index.php/about/.
[i.8] JSONPath: Query expressions for JSON.
NOTE: Available at https://datatracker.ietf.org/doc/draft-ietf-jsonpath-base/.
3 Definition of terms, symbols and abbreviations
3.1 Terms
Void.
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3.2 Symbols
Void
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AE Application Entity
API Application Programming Interface
ASN Application Service Node
CSE Common Services Entity
ID Identifier
IN Infrastructure Node
IoT Internet of things
IPE Interworking Proxy Entity
JSON JavaScript Object Notation
M2M Machine to machine
MN Middle Node
NGSI-LD Next Generation Service Interface Linked Data
OWL Web Ontology Language
RDF Resource Description Framework
RDFS Resource Description Framework Schema
SAREF Smart Applications REFerence ontology
SDT Smart Device Template
TS Technical Specifications
URI Uniform Resource Identifier
URL Uniform Resource Locator
4 Architecture Model
4.1 Information Model
The notion of data synchronization between oneM2M and NGSI-LD systems can be realized by data mapping as well
as interface interworking. The two standards have a different view on information and data modelling and it is
important to understand this difference.
oneM2M takes two approaches regarding information models. One is the modelling and corresponding models'
standardization with Smart Device Template (SDT) (ETSI TS 118 123 [i.4]). Figure 4.1-1 shows the hierarchy of SDT
in oneM2M standard. It is a template to represent device and functional modules. It is a good fit for oneM2M as a
model for M2M/IoT device management and data collection from devices. On the other hand, any service-specific or
user-defined data can be exchanged by oneM2M platforms with and resources, for
example. It allows flexibility to use any preferred data models for IoT services, but the downside of this is lack of data
rd
interoperability to 3 party application providers, because there is no common, cross-domain data model.
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Figure 4.1-1: oneM2M Smart Device Template (SDT) [i.4]
In NGSI-LD systems, it is up to service or data providers to define their domain-specific information models. Indeed,
NGSI-LD standard does not define any domain-specific information models but, instead, defines a common, cross-
domain data model based on the Entity, Property and Relationship concepts that form a Property Graph. Even though
there is no schemas for service implementations, by means of the Linked Data concept, each NGSI-LD Entity instance
rd
and its attributes (Properties and Relationships) can be identified uniquely, so that 3 party application providers,
willing to conform to the underlying cross-domain model, can use data from other data providers.
On top of the cross-domain model, NGSI-LD advocates for higher level models that are domain-specific, to be
constructed and adopted on top of the cross-domain one, to enable full interoperability (oneM2M TR-0007 [i.6]).
4.2 Reference Model
To be able to interwork between two technologies, the application called IPE (Interworking Proxy Entity) which
understands the technologies need existing.
IPE on oneM2M side, acts as Application Entity (AE) and interacts with a Common Services Entity (CSE). The CSE
can be IN (Infrastructure), Middle Node (MN), or Application Service Node (ASN). Even though IPE interact with the
CSE, depending on address of oneM2M resource, IPE can get or manipulate resources in other CSEs via Mcc or Mcc'.
IPE on NGSI-LD side, acts as NGSI-LD application and interacts with a NGSI-LD context broker. Even though IPE
interacts with the NGSI-LD context broker, IPE can get or manipulate entities in other NGSI-LD context brokers using
CSourceRegistration information.

Figure 4.2-1: NGSI-LD - oneM2M Interworking Reference Model
4.3 Types of Interworking Proxy Entity
Depending on the use case, oneM2M data needs synchronizing to NGSI-LD context broker or NGSI-LD data needs
synchronizing to oneM2M. Therefore, in the present document, each solution specifies direction of data
synchronization.
• oneM2M to NGSI-LD: This can be used when services are already implemented and data are already being
stored in oneM2M platform. The goal is for users to get data of oneM2M services using the NGSI-LD API.
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• NGSI-LD to oneM2M: This can be used when device management or actuation is required from NGSI-LD
enabled system (e.g. city operation centre) as well as when oneM2M applications make use of NGSI-LD data.
5 Solution 1 - labels based dynamic interworking
5.1 Introduction
Interworking between oneM2M and NGSI-LD systems requires interfaces and data mapping between the two. It is
realized by the Interworking Proxy Entity (IPE) which understand two standard interfaces and application logics
including data models.
The proposed interworking solution retrieves information on the interworking via labels attribute, which is the oneM2M
resource universal attribute, because all oneM2M resource can have labels. This means that any of the oneM2M
resource in any resource type, can be mapped with NGSI-LD Entity instances. Since NGSI-LD Entity represents a
logical entity, while oneM2M resource can represent a measurement of a device, which is a small portion of a device
model, NGSI-LD Entity can be mapped with one or more oneM2M resource instances.

Figure 5.1-1: Example of Resource mapping between oneM2M and NGSI-LD systems
The given examples in the clause 5.1 only use resource type from the oneM2M standard, but
or resource types can also be applied for this label-based interworking mechanism.
5.2 oneM2M features
This solution uses labels attribute, one of the common attributes in all resource types. Normally in oneM2M labels
attribute is used for discovery purposes like hash tag, but this solution uses for storing mapping rules.
Labels attribute is a list of individual labels and each of them is either a standalone label-key, used as a simple "tag",
that can be used for example for discovery purposes when looking for particular resources that one can "tag" using that
label-key or a composite element made of a label-key and a label-value, separated by a special character defined in
ETSI TS 118 101 [i.1].
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5.3 Resource mapping
In this interworking scheme, the labels attribute contains mapping information between oneM2M resources and NGSI-
LD Entities. The labels attribute has string array data type in ETSI TS 118 104 [i.5], so it is proposed to use key-value
pair in a single token string and there are one or more pairs in the labels attribute on the oneM2M resource instance. The
keys that represent interworking information are defined in the Table 5.3-1.
Table 5.3-1: Interworking mapping labels keys
Label Key Name Data Type Limitation Multiplicity Description
Iwked-Technology String "NGSI-LD" 1 "NGSI-LD"
NGSI-LD
Iwked-Entity-Type String 0.1 Type of the NGSI-LD Entity
Entity Type
List of Data mapping rules for oneM2M resource
Iwked-mapping-rule Mapping Rule 0.1
MappingRule and NGSI-LD Entities
The id attribute of NGSI-LD Entity instance.
Iwked-Entity-ID String n/a 0.1 If not exists, it is decided by "oneM2M
platform ID" + ":" + "ri of oneM2M resource"
Iwked-Related- Other oneM2M resources instances to be
List of String n/a 0.1
Resources combined for the NGSI-LD Entity instance
@context attribute of NGSI-LD Entity
NGSI-LD-Context List of String n/a 1
instance

Table 5.3-2 defines the Mapping Rule data type that is used by Iwked-mapping-rule.
Table 5.3-2: Data type of Mapping Rule
Name Data Type Limitation Multiplicity Description
Identifier of a oneM2M resource
oneM2MResourceId String n/a 0.1
instance
oneM2MAttribute
String n/a 1 Attribute name of the instance
Name
JSONPath [i.8], this is valid when
oneM2MJsonPath String n/a 0.1
the resource is serialized in JSON
Data type for the attribute or the
element referred by JSONPath.
Allowed values are: "String",
oneM2MDataType String n/a 0.1 "Integer", "Double", "Boolean",
"Date", "ArrayString",
"ArrayInteger", "ArrayDouble", or
"ArrayBoolean"
Attribute or element of Attribute
ngsi-
String n/a 0.1 referred by QueryTerm in Query
ldQueryTermAttributePath
Language [i.2]
"Property" or
ngsi-ldAttributeType List of String 1 Type of NGSI-LD attribute
"Relationship"
Data type of ngsi-
ldQueryTermAttributePath.

ngsi-ldAttribute Allowed values are: "String",
List of String n/a 1
DataType "Integer", "Double", "Boolean",
"Date", "ArrayString",
"ArrayInteger", "ArrayDouble", or
"ArrayBoolean"
Since there is no schema
ngsi-ldAttribute Array of information of the NGSI-LD Entity,
n/a 0.1
ParentInformation ParentInformation information on parent attributes is
required
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Name Data Type Limitation Multiplicity Description
Indicates an index of an array
...