Session Date/Time: 24 Jul 2025 07:30

ASDF Working Group Meeting

Summary

The ASDF working group held an in-person meeting to discuss several key drafts including digital twin modeling, non-affordances information, and instance information. The session focused on architectural discussions around extending SDF to handle metadata and contextual information that falls outside traditional affordances (properties, actions, events). The group also received updates on the NIPSI protocol work and discussed procedural matters including document adoption and authoring.

Key Discussion Points

Architecture and Document Relationships

Elephant analogy: Carsten noted that the three main drafts (non-affordances, digital twin, instance information) represent different perspectives on the same architectural challenge rather than competing approaches
Instance vs Model distinction: Critical need to separate instance representation formats from models, which is new to the SDF architecture
Terminology challenges: Discussion around naming conventions, with "SDF context" preferred over "SDF non-affordances" for descriptive metadata

SDF Extensions for Non-Affordances Information

Purpose: Introduce structured way to represent non-interactive, descriptive metadata within SDF models
Rationale: Real-world things require metadata like physical dimensions, installation location, manufacturer info, certification data
Implementation: Lightweight, backward-compatible extension using new SDF class
Runtime messages: Three types proposed - context snapshot, identity manifest, and context patch

Digital Twin Modeling

Standards alignment: Based on ISO digital twin standards with SDF extensions
Information attributes: Static data (identifier, location, owner) vs dynamic data (status, maintenance)
Relationships: Three types defined - physical, functional, and semantic relationships
Implementation procedure: Eight-step process for digital twin implementation

Instance Information Draft

Scope: Focuses on runtime instance messages and contextual metadata in operational data
New concepts: Proof shots (device status overview), constructors (initialization), event history
Protocol mapping: Needs to work across different ecosystems beyond just NIPSI

NIPSI Protocol Updates

Status: Draft version 10 released with hackathon-driven improvements
Major issues resolved:
- Moving from path parameters to query parameters to avoid server implementation issues with encoded characters
- Protocol mapping generalization beyond non-IP protocols
- New NIPSI-specific problem type registry
- Media type handling improvements

Decisions and Action Items

Technical Decisions

Query parameters: Consensus to move NIPSI API from path to query parameters to resolve server compatibility issues
Protocol mapping: Agreement to split protocol mapping into separate draft from NIPSI
Problem types: Create NIPSI-specific problem type registry rather than using generic HTTP registry
Media types: Introduce application/nipsi+json media type for NIPSI-specific formats

Document Actions

SDF Relations: Lorenzo to become co-author to advance this document
Protocol Mapping: Extract as separate draft from NIPSI (no adoption call needed for split documents)
SKIM Extension: Create separate draft for SDF extensions to SKIM device model

Process Items

Working Group Adoption: Discussion on timing - some prefer early adoption to show working group interest, others prefer waiting until approach is clearer
Author Recruitment: Need approximately 3 more active authors across documents to reduce dependency on current core contributors

Next Steps

Scheduled Meetings

Virtual Interim: August 20th, 10:00 Helsinki time (accommodating global timezone challenges)
September Interim: TBD, similar timing
Montreal IETF: Plan comprehensive document hackathon focused on collaborative editing rather than presentations

Immediate Work Items

Continue resolving remaining NIPSI GitHub issues (~49 open, ~15 ready to close)
Progress architectural discussion on non-affordances/context/instance information convergence
Begin work on separated protocol mapping draft
Address URL encoding issues as broader IETF concern (coordinate with area directors)

Long-term Goals

Converge the three main drafts into coherent architectural approach
Establish clear model vs instance separation in SDF ecosystem
Expand implementation testing (potential IETF network experiments with Wi-Fi 7 APs)
Increase working group participation and authorship diversity