W3C

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

02 March 2026

Attendees

Present
Bert_Bos, Frederic_Le, Hiroki_Endo, Juanjo_Hierro, Kaz_Ashimura, Kunihiko_Toumura, Michael_Koster, Tomoaki_MIzushima, Torbjorn_Lahrin
Regrets
-
Chair
Kaz, Koster
Scribe
Bert, kaz, mjk

Meeting minutes

Quick question to Juanjo

kaz: How long will the presentation be? 30 mins?

juanjo: a bit longer

kaz: ok. let's use 40 mins then.

Logistics (Guests, Meeting schedule, etc.)

kaz: First some logistics: I'm sharing screen, agenda, three guests.

Minutes review: 25 Jan 2026

<kaz> 25 Jan 2026

kaz: Review of last minutes.
… We take minutes in IRC and then publsih them on GitHub.
… We had some discussions and did some planning.
… Do we approve the minutes?

<Bert> +1

RESOLUTION: minutes approved

Kaz: Let's start with reviewing the plan, before we go to the talk.

Basic Plan for 2026

<kaz> schedule.md

Kaz shows the planning page on GitHub.

Kaz: My suggestionis to publish just one document with the three topics as sections (survey, best practice, basic use cases)

<Bert> Sound good to me.

kaz: The charter expires end of July.

Deliverables

kaz: We need to discuss who will be editors for the document this month.
… And try to publish an initiual draft in April
… And update in May. Publish as IG Note.

juanjo: will our contributions be included in the document?

kaz: We can include link. So answer is yes.

IG Charter

kaz: About charter: We can extend a charter for a few months. I suggest we start in June to discuss a new charter.
… Then AC review in August and new group starts in September.
… So let's start with this plan and we modify it as we go along.
… So let's talk now about FIWARE

Collaboration with ETSI/FIWARE on NGSI-LD

Juanjo Hierro sharing screen.

<kaz> [slide 1]

juanjo: Martin Bauer could no be here today.
… I'll reference work we do in ETSI.
… FIWARE is a an Open Source initiative for smart solutions in different sectors, like facturies.
… It allows to create platforms.
… Our members are active in different standards bodies, including W3C and ETSI.
… An important part of our work is how to make different standards work together.

<kaz> [slide 2]

juanjo: This is based very much on Digital Twins, or also a model of the real world.
… Model constantly updated based on various sources.
… Digital Twins means not necessarily 3D representations.
… It is data management, involved in execution of actions.
… An approach based on a System of Systems.
… Can be used in an organization, such a city, a port...
… Work on standardize interchange of information, e.g., between a city and its port, or between the city and a logistics operator.

<kaz> [slide 3]

juanjo: Digital Twins and System of Systems approaches used for integration at multiple levels.

<kaz> [slide 4]

juanjo: A Digital Twin is a kind of replica of an asset.
… E.g., is sombody wants to make a claim about something, a street, e.g., then the claim will also be modeled as a digitial twin.
… We are going to add Actions to our model as well.
… Typically a Digital Twin also has location data.
… A Context is the state of all digital twins in the collection.
… A standard API is a first needed step.
… But the systems also need to be able to talk about the same concepts, with the same semantics, e.g., temperature.
… So need command data models for digital twins.

<kaz> [slide 5]

juanjo: NGSI-LD API developed in ETSI.
… NGSI-LD is a simple (but powerful) REST API.
… Entity types and attributes mapped to paths.
… HTTP verbs GET, PUT, PATCH, etc.
… API developed based on developers' experience.
… Includes e.g., geo-queries, e.g., all all entities in an area.
… Also notifications to subscribe to.
… Queries but also push of information.
… To support different visualizations, cen askfor results in the form of GeoJSON.
… But can also be in other formats, such as key-value pairs.
… Supports batch operations (operations on multiple objects at a time).
… Support temporal operations, such as getting time series.
… A Context Broker is an implementation.

<kaz> [slide 6]

juanjo: See https://github.com/smart-data-models

<kaz> [slide 7]

juanjo: Shows diagram of reference architecture.
… Showing it for Smart Cities.

juanjo: Examples: air quality, traffic level, sensors and devices to update attributes of the system.
… A Context Broker is a means to intregrate the information.
… Some information relevant for some processes.
… Decoupling the supplier of information form the consumer of that information.
… Consumer of data interacts with Context Broker, but need not care about how the info got there.
… Updates of data are a constant stream. Can now integrate AI to get insights from the incoming data.
… E.g., I may have a system to predict traffic.
… Can then add an attribute to the system with the predicted traffic.
… There may also be a 3D representation.
… Extension to data spaces: market for data.

<kaz> [slide 8]

juanjo: FIWARE used by more than 300 cities already.
… Not just in Europe, but also in Japan, India, Korea, etc.

<kaz> [slide 9]

juanjo: About relation with WoT
… a Thing can map to an Entity in NGSI-LD.

<kaz> [slide 10]

juanjo: WoT Thing Model was interesting to us. Thing Description is an opportunity for us.
… And we want to push NGSI-LD as a Deriving Thing Description from Thing Model.
… It can provide a default REST API.

<kaz> [slide 11]

juanjo: NGSI-LD can make new things possible in WoT, such as queries over multiple things.

<kaz> [slide 12]

<kaz> ... (gives summary)

<kaz> [slide 13]

juanjo: We now have a first proposal for Actions and that can lead to a one-to-one mapping with WoT.
… Next steps are @@

kaz: Agree with this proposal
… we can bring a proposal to the WoT working group
… we need to define how the integration of TD and Smart Models works
… how to handle semantic information including geolocation data

Juanjo: we can describe device APIs better using Thing Description and Thing Models in a JSON-LD format
… Another aspect is that NGSI-LD doesn't constrain the security framework
… We can integrate with VC
… and position several W3C standards in the Smart City arena

kaz: I agree with you about using the other W3C standards also like VC and DID :)

mjk: thank you!
… also fully agree with you
… basically you have graph API for smart cities
… applying WoT to that model would make it even smoother
… device api described by Thing Description
… to me, all that would make sense
… and likd the direction
… need to figure out how to bring the ideas

kaz: let's come to the WG with concrete ideas

kaz: would like to arrange another meeting to focus on stakeholders
… AOB?
[adjourned]

Summary of resolutions

  1. minutes approved
Minutes manually created (not a transcript), formatted by scribe.perl version 248 (Mon Oct 27 20:04:16 2025 UTC).