W3C

– DRAFT –
Web-based Digital Twins for Smart Cities IG

08 September 2025

Attendees

Present
Juanjo_Hierro, Kaz_Ashimura, Martin_Bauer, Michael_Koster, Tomoaki_Mizushima, Torbjorn_Lahrin
Regrets
-
Chair
Koster
Scribe
kaz

Meeting minutes

Logistics

Guests and IEs

Kaz: Torbjorn is now an official IE
… also we have two guests from ETSI/FIWARE

Koster: yes
… discussion about NGSI-LD
… also Torbjorn from the Nordic Smart Cities activity
… welcome!

Quick Intro

(starting with Juanjo)

Juanjo: FIWARE tech committee Chair

Martin: principle standardization
… vice Chair of FIWARE committee
… NGSI-LD from the beginning

Torbjorn: nice to have you both
… in Sweden, we have Nordic Smart City project
… using the platform based on FIWARE stuff
… so welcome to see the technology
… also smart city community within W3C
… also engaged with European dataspace work
… also Chair of strategic coordination for Metaverse

Koster: a lot of activities around those topics
… move things forward in more coordinated way would be nice

Minutes

July-7

Koster: (goes through the previous minutes)
… we're working on the technology landscape
… adding more categories for the technology
… also vocabulary is very important
… pretty broad activities

Torbjorn: Mark and I had discussion about ontologies for smart cities
… Mark has been working on that, that's good
… the problem is there are many of them
… people have their own ontologies
… if we can have some ontology for everybody, that would be great
… we have 3-4 vendors in Sweden but all of them have their own ones
… make one changes their own ontology
… so there is a challenge about alignment and interoperability
… sharing data within, e.g., European Dataspace
… convergence is needed
… happy to have discussion about the problem
… would elaborate the challenges

Juanjo: one of the advantages why FIWARE has become popular
… across various cities
… guess you're familiar with the models
… smart data models, etc.
… associated to that
… what we have is really implemented approach
… decided based on communities' requirements
… company organization implementing and contributing to real projects
… analysis and potential collisions
… we have so far big number of cities working on that
… and widely adopted
… implementing FIWARE's datamodel
… in many cities before FIWARE is around
… there was a gap on how to integrate things
… we handle that based on the idea of digital twins
… fancy tools of 3D visualization itself is not important but the data model is important
… structured layer to be used
… context broker implements the mechanism
… this arouse to overcome the issues with old systems
… adaptation of the mechanism will accomplish the interoperability
… between one data and another
… what is important is the data
… what data to be provided by the system
… e.g., for a traffic management system
… also what kind of data to be used to improve the system
… all the data to be harmonized with each other
… ID management in addition to NGSI-LD
… would like to talk about the background around FIWARE today

Kaz: great
… actually, your presentation is the main topic for today
… please let Koster wrap-up the minutes review quickly

Koster: ok
… (wrap-up the minutes review)
… (quickly goes through the rest of the minutes from July-7 meeting)
… Mark Fox gave nice description about his ontology work
… any comments/questions?

(none)

(minutes approved)

F2F Meeting at TPAC 2025

Koster: TPAC is the main tech meeting of W3C
… we'd hold a F2F meeting as breakout during TPAC

Torbjorn: when to have that?

Kaz: probably on Wednesday, Nov 12

Torbjorn: hybrid?

Kaz: yes
… and we can decide on the date later :)

Koster: sounds good

NGSI-LD Collaboration

@@@ slides tbd

Kaz: do you think you can share your slides publicly?

Juanjo: yes, after some changes

Kaz: great

About FIWARE

Juanjo: (gives background about FIWARE)
… IoT-enables smart solutions
… also smart organizations
… working on dataspaces for 12 years or so
… invocation of services
… FIWARE community intends to contribute to creation/evolution

Digital Twins as basis for the architecture...

Juanjo: digital twin representation for the real world
… constantly keep up to date

Digital Twins: an approach for integration at multiple levels...

Juanjo: architecting, integration, ...

What are we referring to as Digital Twins

Juanjo: digital "replica of an asset
… characterized by attributes
… values of attributes may change over time
… typically have a location
… APIs about how to implement actions
… also handling common data models
… NGSIv2 => ETSI GSI-LD API

Data Exchange API: ETSI NGSI-LD

Juanjo: (Context Broker connected with bus, citizen, shop, ...)
… not only for citizens but various industry domains
… some of the targets are related to multiple domains
… NGSI-LD is a simple powerful REST API
… simple: what you want in a RESTful API
… entity types, entities, attributes
… GET, POST, PUT, PATCH, DELETE operations
… powerful: supported operations
… geo-queries, subscription/notification, pull/push, multiple data rendering, ...

FIWARE driving key standards: Smart Data Models

Smart Data Models

Juanjo: collaborating with relevant orgs
… how the map into JSON-LD also
… data modes based on well-established standards, e.g., schema.org, SAREF, IEC CIM in Energy

Smart Vertical solution: Reference Architecture (Smart Cities)

Juanjo: multi-tier architecture
… 4 major layers, data acquisition layer, processing/analysis/visualization
… AI/ML algorithm to be also applied

Example: Initial Smart City Reference Architecture

(diagram)

Juanjo: (describes the diagram)
… there might be a system which doesn't require FIWARE standard
… but the architecture including the Context Broker can work that as well
… bring all the data to the common data layer
… the data can be consumed by the other vertical solutions
… these days considering VC/DID as well for identification management
… ability to create market places also
… establish the contract for various services

WoT:Things and GSI-LD:Entities

Juanjo: a WoT Thing may map well to an NGSI-LD Entity
… (shows an example Thing Description about that idea)

Compatibility of NGSI-LD with Thing Models/Descriptions

Juanjo: WoT may specify what would be the default Thing Description derived from a Thing Model
… then how to implement Actions for NGSI-LD should be clarified
… (shows some more discussion points)

Summary

Juanjo: WoT and NGSI-LD look compatible
… opportunity to specify how they can work together
… but we need further clarification to see the details
… we did some work about that including DTDL, etc.
… we need standard way for digital twin representation as well
… how to harmonize that layer is also a question
… so collaboration with W3C has been established
… 1:1 conversion with WoT Thing Description to be discussed
… Property is comparably straightforward
… that's the basic background of the collaboration

Koster: that's really exciting!
… sort of start-off for further discussion
… JSON Schema as basic definition language, for example

Smart Cities IG Charter

Kaz: completely inline with the Charter

Torbjorn: also interested
… a bit curious about how to support the declaration for Citiverse, etc.
… what possibility do you see?

Juanjo: depends on what we find
… we already have experience on integrating different technologies with NGSI-LD
… integrating more out-of-desk things
… it's still something to be developed
… so far our impression is very promising

Torbjorn: ok
… another question about the main branch for integration
… we're referring to NGSI-LD also
… on top of NGSI-LD

Juanjo: this was something several years ago
… reference implementation of each component
… we're going for more inclusive approach
… there are several different context brokers
… there is no enforcement to force people make commitment to our repository, for example

Torbjorn: bringing what we did back to the NGSI-LD repo?

Juanjo: there is the FIWARE catalog but you don't have to take all of them

Torbjorn: there is a sensitive branch when people make contributions
… there are several vendors from Sweden, though
… would be helpful if we could clarify how to organize FIWARE stuff and W3C stuff

Kaz: that's really a good point
… and should be included into the topics for this IG
… for example, W3C Registry mechanism could be helpful for that purpose

Koster: exactly, this is really good point
… any other business for today?

Next meeting

Juanjo: when to have the next meeting?

Kaz: usually hold on the 4th Monday
… but will create a Doodle poll to fine a good slot for people

Koster: ok
… meeting adjourned

[adjourned]

Minutes manually created (not a transcript), formatted by scribe.perl version 244 (Thu Feb 27 01:23:09 2025 UTC).