Session Date/Time: 17 Mar 2025 08:30

CBOR Working Group Meeting Minutes

Summary

The CBOR working group met to discuss three main items: CBOR Packed (Packs) tag consumption concerns, adoption of the DNS CBOR draft, and Extended Diagnostic Notation (EDN) string escaping mechanisms. Key discussions centered around conserving precious CBOR tag resources for Packs, evaluating the DNS CBOR draft for working group adoption, and resolving technical details for EDN string handling and Unicode escaping.

Key Discussion Points

CBOR Packed (Packs) Tag Consumption

Tag Resource Constraints: Analysis shows only 158 one-plus-one tags remaining free out of 232 total, with 74 already consumed over 11 years (≈7 tags/year)
Current Proposal: Draft requests 40 tags (≈25% of remaining one-plus-one tags), raising sustainability concerns for multi-decade usage
Three Approaches Discussed:
- Reduced approach: Scale down to 24 tags (16 + 8 for straight/inverted references)
- Radical reduction: Use zero additional tags by employing tag 6 with two-element arrays
- Status quo: Proceed with 40 tags as currently specified
Trade-offs: Radical reduction conserves tags but adds ~1 byte overhead per argument reference; reduced approach offers middle ground

DNS CBOR Draft Adoption

Motivation: Achieve 50% message size reduction in constrained networks using CBOR encoding
Recent Updates: Added resource record set summarization capability and name compression using Packed CBOR
Implementation Status: Draft has been shared with DNS experts and received positive feedback
Charter Compatibility: Action item for chairs to verify alignment with CBOR working group charter

Extended Diagnostic Notation (EDN) String Handling

Extension Requirements: Need third-party extensibility while maintaining isolation, implementation flexibility, and permissionless innovation
String Types: Double-quoted (JSON-compatible), single-quoted (bare), and app strings (prefixed, single-quoted)
Unicode Escaping Debate:
- Consensus items: Valid JSON should be valid EDN, editor syntax highlighting support needed
- Open questions: Whether to support \u{...} format alongside JSON's \uXXXX, escaping mechanisms for app strings
Key Tension: Balance between providing universal Unicode escaping vs. leveraging existing format-specific mechanisms

Decisions and Action Items

Chairs: Verify DNS CBOR draft alignment with working group charter
Chairs: Issue call for objections on adopting DNS CBOR draft
Chairs: Schedule interim meetings (possibly 90 minutes instead of 60 minutes for future sessions)
Working Group: Continue EDN escaping discussion on mailing list due to time constraints
CBOR Packed: No final decision made; feedback indicated preference for radical reduction approach, but benchmarking needed

Next Steps

CBOR Packed: Develop benchmarks to quantify performance impacts of different tag allocation approaches
DNS CBOR: Await charter review and formal adoption process
EDN: Resume detailed technical discussion on mailing list regarding string escaping mechanisms, Unicode handling, and extension compatibility
Interim Meetings: Check secretariat-provided dates for upcoming interim sessions