Session Date/Time: 09 Feb 2022 15:00

CBOR

Summary

The CBOR working group met to discuss the status of the file-magic draft and a new proposal for "illusion of values" in CBOR diagnostic notation. The file-magic draft (draft-ietf-cbor-file-magic-08) was deemed ready for a shortened Working Group Last Call (WGLC). A new mechanism using three dots (...) for indicating omitted data in diagnostic notation, backed by a new CBOR tag (T888) for machine processing, was presented and received positive initial feedback.

Key Discussion Points

Audio Issues: The meeting began with a brief discussion of a participant's audio setup causing an echo, which was subsequently resolved.
IETF Vienna Attendance: Participants briefly discussed their travel plans for the upcoming IETF meeting in Vienna, with some awaiting travel approvals.
draft-ietf-cbor-file-magic-08 Status:
- draft-ietf-cbor-file-magic-08 was submitted, primarily containing document cleanup (normative/informative distinctions) and tutorial changes.
- Carsten, as editor, confirmed that previously discussed historical statement changes were already incorporated in earlier versions (0.14 or 0.15).
- A sense of those present indicated no objections to progressing the document.
Illusion of Values in CBOR Diagnostic Notation:
- Carsten presented a proposal for adding an "illusion mechanism" to CBOR diagnostic notation. The motivation is to simplify examples in RFCs and other documents by omitting less important parts.
- Proposed Syntax: Three dots (...) would represent one or more omitted data items.
  - Examples: [1, 2, ..., 5, 6] for arrays, {1: "a", ...} for maps.
- String Illusion: The ... could also be used within text or byte strings (e.g., "part1" ... "part2"), leveraging RFC 8610 Appendix G.4 for concatenated strings. This would require diagnostic parsers to implement G.4.
- Machine Processing: To allow machine generation and parsing of examples with illusions, a new CBOR tag, T888, was proposed.
  - When a diagnostic notation tool is configured to process illusions, it would convert ... to T888(null) for simple omissions or T888(["part1", null, "part2"]) for illusions within strings.
  - This tag would signal that the data is intentionally incomplete.
- Parser Configuration: It was emphasized that a special flag would be needed when invoking diagnostic notation tools to enable illusion processing, preventing unintended interpretation of ... or T888.
- CDDL Interaction: Carsten raised a question about potential interactions with CDDL, such as CDDL guiding or verifying illusions, but no concrete use cases were identified at this time. A participant noted the resemblance between the T888 array structure and CDDL's cat operator.
- Initial Feedback: The proposal received positive feedback, particularly for its utility in machine-generated examples and ensuring that intentionally incomplete examples can be processed and verified without errors.

Decisions and Action Items

Decision: The working group will proceed with a shortened, one-week Working Group Last Call (WGLC) for draft-ietf-cbor-file-magic-08.
- Action Item: Michael (Chair) will initiate the WGLC and prepare the IESG shepherd's write-up if no issues are raised during the WGLC.
Decision: Carsten received encouragement to proceed with developing the "illusion of values" proposal.
- Action Item: Carsten will implement the proposed illusion mechanism in his diagnostic package.
- Action Item: Carsten will draft a specification for the illusion mechanism, potentially as an addition to an existing extended diagnostic notation draft or a new standalone document.

Next Steps

Monitor the file-magic WGLC.
Carsten will work on the implementation and draft for the illusion mechanism.
The next WG meeting is scheduled for two weeks from now.