Markdown Version | Transcript | Session Recording

Session Date/Time: 22 Apr 2026 14:00

CORE

Interim Meeting Minutes - April 22, 2026

Summary

The CoRE Working Group held an interim meeting to discuss the progress of several active drafts. The session focused on two main areas: resolving final issues for [draft-ietf-core-conditional-attributes] and a deep dive into the YANG-CBOR ecosystem, including [draft-ietf-core-comi] (CoRECONF), SID file management, and a new proposal for YANG stand-ins.

Key Discussion Points

1. Conditional Query Parameters for CoAP Observe

Presenter: Bill Silverajan Slides: Conditional Query Parameters for CoAP Observe

• Status Update: Version -12 was recently released, incorporating feedback from Jaime Jiménez, Esko Dijk, and Christian Amsüss. Changes include terminology updates and implementation considerations regarding SenML.
• Interface Description (if=): Christian Amsüss and Carsten Bormann advocated for defining a specific interface type (e.g., if=core.cond-attr) in the link format. This allows servers to advertise support and prevents URI namespace conflicts with other query parameters.
• Discovery and Error Handling: Bill Silverajan initially questioned if this belonged in this draft versus a more general URI/interface draft, but agreed to explore adding a single interface type to version -13. There was a consensus that servers should treat unsupported conditional query parameters as a "no-op" (ignoring them) rather than returning an error, consistent with general CoAP behavior.
• Timeline: The chairs proposed, and the author agreed to, a tentative milestone for a publication request in October 2024.

2. SID Issues and YANG-CBOR

Presenter: Vojtěch Vilímek Slides: core-interim-05-vilimek

• SID File Versioning: Vojtěch Vilímek raised concerns about SID file revisions when the underlying YANG module has not changed. Michael Richardson argued that if a SID allocation change is incompatible, the YANG module should be revised (even if no content changes) to ensure synchronization. Carsten Bormann noted that SID revisions should allow fixing errors without necessarily "wagging the dog" (forcing YANG changes).
• RFC 9595 Errata: Discussion on finalizing errata for SID assignments. The existing errata need to be updated to include missing assignments for input and output nodes in the example JSON.
• pyang Maintenance: Vojtěch Vilímek has merged several bug fixes into the upstream pyang master branch (mbj4668), specifically addressing SID file descriptions, sub-module pathing, and dependency revision duplications.

3. Instance Identifier Rules and YANG Stand-ins

Presenter: Vojtěch Vilímek Slides: core-interim-05-vilimek

• Missing Rules for Instance Identifiers: Vojtěch Vilímek highlighted gaps in [draft-ietf-core-yang-metadata] (RFC 9254) regarding lists without keys and leaf-lists. He proposed index-based rules to ensure YANG parity in CBOR. Carsten Bormann requested specific use cases to determine if these identifiers are functionally necessary for RESTCONF/CoRECONF operations.
• YANG Stand-ins: A proposal to improve efficiency by replacing "stringly-typed" YANG definitions (IP addresses, dates, MACs) with native CBOR encodings via a "stand-in" mapping file.
• CoRECONF Integration: There was a sense among participants that the stand-ins mechanism should be a requirement for [draft-ietf-core-comi] to ensure efficiency in constrained environments.

4. CoRECONF (CoAP Management Interface)

Presenter: Vojtěch Vilímek Slides: core-interim-05-vilimek

• Event Subscriptions: Discussion on the requirement that observe responses "must carry one or multiple notifications." Vojtěch Vilímek pointed out that a newly booted device might not have notifications to send. A proposal was made to allow an empty notification list specifically for the subscription initiator.
• Transport and Performance: Maria Matějka noted throughput limitations of CoAP over UDP due to the 16-bit message ID. Carsten Bormann suggested adding a "Transport Options" section to [draft-ietf-core-comi] to discuss using CoAP over TCP [RFC 8323] or potentially QUIC for high-performance requirements.
• Pagination: Vojtěch Vilímek argued for including list pagination as a requirement in CoRECONF to handle large data models (e.g., routing tables). Carsten Bormann suggested investigating the "Series Transfer Pattern" defined in [draft-ietf-core-responses] as a potential solution.
• Inter-WG Coordination: The group discussed the need for better synchronization with the NetMod working group regarding new versions of YANG.

Decisions and Action Items

• [draft-ietf-core-conditional-attributes]: Bill Silverajan to prepare version -13 including the definition of a single interface type (if=) for discovery.
• pyang: Vojtěch Vilímek and Carsten Bormann to coordinate offline to clean up the pyang repository branches and merge sub-module fixes.
• SID Errata: Vojtěch Vilímek to update the errata report for RFC 9595 on GitHub before submission.
• WGLC: Participants are reminded to review [draft-ietf-core-oscore-key-limits], which is in Working Group Last Call until May 4, 2026.

Next Steps

• The chairs will update the milestone for [draft-ietf-core-conditional-attributes] to October 2026.
• Further discussion on the "Series Transfer Pattern" and its application to CoRECONF pagination will be scheduled for a future interim or conducted on the mailing list.
• A dedicated discussion on the adoption of the YANG stand-ins draft is expected soon.

Related Documents

draft-ietf-core-comi, draft-ietf-core-conditional-attributes, draft-ietf-core-oscore-key-limits, draft-ietf-core-responses, draft-ietf-core-yang-metadata