Markdown Version | Session Recording

Session Date/Time: 09 Apr 2025 12:00

ASDF

Summary

The ASDF Working Group held its third interim meeting of 2025. The session included a working group status update, updates on the NIPY and Digital Twin drafts, and discussions on the SDF-Link adoption call, a new draft on SDF Extension for Non-Affordance Information, and a newly submitted Internet-Draft on Instance Information. Discussions also covered future meeting logistics, including a planned face-to-face meeting in Madrid and the next virtual interim.

Key Discussion Points

• Working Group Status Update:
  • The ASDF WG was rechartered in June 2024.
  • SDF has been approved by the IESG as a Proposed Standard. Minor background issues with IANA registry references (e.g., Cinema units vs. names) are being resolved.
• NIPY Updates:
  • A new version (04) of the NIPY draft is available, incorporating feedback from previous meetings and hackathons.
• SDF-Link Adoption Call:
  • The Working Group adoption call for the SDF-Link draft is ongoing and scheduled to end on Friday. General technical support was expressed.
  • The basic idea is to map the Core Link Format structure to SDF, allowing for modeling and restrictions of target attributes. Potential for shorthand notation for model translation use cases was raised.
• Digital Twin Draft (version 7):
  • Presented mapping of information attributes from ISO 23247 Part 3 (Digital Twin standard) to SDF classes.
  • Distinction was made between SDF things with both non-affordance and affordance attributes (e.g., connected sensor) versus those with only non-affordance attributes (e.g., table, chair).
  • Future plans include developing examples and guidance for modeling and registering SDF for digital twins, and mapping to ITU-T Y.4905 (Digital Twin Federation).
  • Discussion noted the relevance of SDF relations for describing complex digital twin relationships.
• SDF Extension for Non-Affordance Information Draft:
  • Motivation: Current SDF models affordances (interactive capabilities); however, real-world applications require non-interactive metadata (e.g., location, dimensions, manufacturer details) for completeness and integration with systems like digital twins or asset platforms.
  • Definition: "Non-affordance" is defined as attributes of a thing not directly related to its interactive capabilities, covering descriptive and contextual information.
  • Use Cases: Asset tracking (size, weight, location of containers), smart buildings (sensor location, room, mounting), regulatory compliance (model numbers, firmware, certifications).
  • Proposal: Introduction of a new class SDF non-affordance within SDF or SDF object, following a simple structure (name, type, description, unit) aligned with existing SDF models.
  • Discussion: Query on structural differences/similarities to SDF property. The proposed SDF non-affordance class looks structurally similar to SDF property or SDF event but with different semantics (non-interactive, off-device information). Whether to reuse existing grammar for properties/events was discussed, considering semantic distinction.
• Instance Information Internet-Draft:
  • Core Concepts: SDF describes an interaction model (how to talk to a device), primarily focusing on data in flight. The draft aims to address instance information (what is known about a specific instance) and data at rest.
  • Abstract vs. Ecosystem Specifics: SDF focuses on abstract modeling; ecosystem specifics will always exist.
  • "Off-Device" Concept: Replaces "non-affordance" for modeling purposes. Information deemed "off-device" (e.g., location, serial number) is structurally isomorphic to SDF properties, allowing existing tools to work. A new off-device quality (true/false) is proposed.
  • SDF Instance: Introduces SDF instance to describe specific instances (e.g., boat007). Instances point to their SDF thing models, avoiding repetition of model information. Nested instances (e.g., a heater within a boat) are supported. Context information (e.g., security IDs, parent instance pointers) can be included.
  • Terminology:
    • Representation: Defined in REST, applies broadly to ecosystems.
    • Message: Instance information exchanged during interaction. SDF models provide the structure for messages.
    • Instance Identity: Mechanisms binding interconnected instances (e.g., thing, digital twin) across different embodiments.
    • Proofshot: A snapshot of all information obtainable from an instance at a point in time. May not be complete due to device limitations or current state. Relates to streaming telemetry as a sequence of deltas updating a proofshot.
    • Construction Message: Information specifically for initializing or commissioning a device or digital twin, distinct from a proofshot which might contain un-settable data (e.g., a derived encryption key).
  • Discussion:
    • Confirmation that "off-device" information (or "off-internet"/"off-interaction" as suggested) is structurally the same as affordance data, thus leveraging existing SDF modeling.
    • Clarification on proofshots and their relation to streaming telemetry (deltas updating a proofshot).
    • Question on modeling non-interactive physical things (tables, chairs) and the need for good examples.
    • Concerns about recursion in SDF instance and parser complexity/memory for low-end devices; however, instances on low-end devices can be very simple, relying on references for full context.
    • Emphasis on documenting processing models for SDF documents, including new ways of describing instances.
    • Discussion on using SDF relations to describe nuanced relationships between instances (e.g., active/standby motor for a boat, or association of people with a cantina). Current SDF relations are at the model level; extension to instance level needed.

Decisions and Action Items

• Decision: The Working Group will hold a face-to-face meeting in Madrid.
• Decision: The next virtual interim meeting is scheduled for May 14th at the same time slot.
• Action Item: Chairs (Lorenzo Cornell) to set up logistics for the May 14th interim meeting.
• Action Item: Ari (and others) to review the Digital Twin draft and discuss SDF relations offline with the authors.
• Action Item: Authors and WG participants to gather and provide examples for the SDF-Link and Instance Information drafts to aid development and clarification.
• Action Item: Authors of the Instance Information draft (Karsten, Yan) to:
  • Check interaction with NIPY, especially on the context level.
  • Integrate examples from other relevant drafts.
  • Develop new versions of the document.
• Action Item: The Working Group will consider tackling the documentation of processing models for SDF documents in the near future.
• Action Item: Carsten, Yan, and Ari to further investigate how SDF relations can be applied and extended to the instance level for describing complex instance relationships.

Next Steps

• Monitor the conclusion of the SDF-Link Working Group adoption call.
• The chairs will finalize the logistics for the May 14th virtual interim meeting and begin to prepare its agenda.
• Participants are encouraged to review the Instance Information and Non-Affordance drafts and provide feedback, particularly regarding examples.
• Further discussions on the interplay between SDF relations and instance information will take place.
• Preparations for the face-to-face meeting in Madrid will commence.