**Session Date/Time:** 22 Nov 2023 15:00

# [CORE](../wg/core.html)

## Summary

The CORE Working Group discussed the status of `COVI` and `OSCAR-AD-HOC` documents. A significant part of the meeting focused on the discoverability of CoAP URIs and interface types, leading to a proposal for an informative GitHub Wiki page. Updates to the `HRE` document were presented, including new CoAP options for CRIs and a discussion on handling scheme numbering in IANA registries and CoAP options. The group also noted an ongoing adoption call for a document.

## Key Discussion Points

*   **Document Status Updates:**
    *   **`COVI`:** Remains in ISG processing with two discusses from older versions. Progress is pending AD action to clear these, with delays attributed to recent IETF discussions and upcoming holidays.
    *   **`OSCAR-AD-HOC`:** Expected to merge PRs and submit version 10 early next week, with the aim of being considered at the November 30th ISG meeting.
*   **Discoverability of CoAP Interface and Resource Type URIs/URNs:**
    *   Esco raised a question regarding the registration and discoverability of CoAP interfaces defined using URNs/URIs.
    *   Current IANA registry policy does not allow registering URNs/URIs as they are managed by the namespace owner (e.g., `/.well-known/core-parameters`).
    *   Concern: Without registration, it is difficult for practitioners to find an overview of all defined CoAP attributes like interface types or resource types.
    *   Discussion explored alternative methods for making this information discoverable, given IANA's reluctance to create new registries for informative purposes.
    *   A Wiki page on the CoRE GitHub organization was proposed as an informative resource to list organizations or specifications defining such CoAP attributes.
    *   It was suggested that IANA could be asked to add a note referencing this Wiki page in the existing CoAP Interface Type (`if`) and Resource Type (`rt`) registries.
*   **HRE Document Updates (CRIs in CoAP):**
    *   **CRI Conversion Procedures:** Carsten presented the need to add procedures for converting CRIs to CoAP options (e.g., `Uri-Path`, `Uri-Query`), analogous to sections 6.4 and 6.5 of RFC 7252 for URIs. This would include addressing the anomaly of a trailing slash after an authority.
    *   **New CoAP Options for CRIs:**
        *   **`Proxy-CRI` Option:** A new CoAP option, analogous to `Proxy-URI`, was proposed. It would carry a CBOR-encoded CRI as opaque binary data. Semantically, it functions similarly to `Proxy-URI`, with the `Proxy-CRI` overriding `Proxy-URI` if both are received (though sending both in a request would be forbidden).
        *   **`Proxy-Scheme-Number` Option:** An alternative to `Proxy-Scheme` (which uses text labels), this option would use a numeric scheme ID. This is relevant given the new IANA scheme registry.
            *   A challenge was noted with CoAP's unsigned integer encoding for options, while CRIs use negative numbers for schemes (e.g., -1 for CoAP, -2 for CoAPS).
            *   Two approaches were discussed:
                1.  Map negative CRI scheme numbers to unsigned option values (e.g., -1 maps to 0, -2 maps to 1).
                2.  Modify the IANA scheme registry itself to use unsigned numbers (0 for CoAP, 1 for CoAPS, etc.) and apply a negation (e.g., `- (value + 1)`) only when constructing a CRI. The latter was considered "easier to explain" and more palatable.
    *   **Location URI with Different Schemes:** Carsten raised a point about the current inability to specify a `Location-URI` with a different CoAP scheme (e.g., CoAP+TCP). If this functionality is added, a numeric option would be preferred over a text-based one, given the existence of the scheme registry.
    *   **New Option Numbers:** Discussion on appropriate option numbers for `Proxy-CRI` and `Proxy-Scheme-Number`, suggesting values in the 1-255 range for single-byte encoding, potentially by adding 200 to the existing `Proxy-URI` (35) and `Proxy-Scheme` (39) numbers for memorability.
*   **Adoption Call:** There is an ongoing adoption call for a document. Participants are encouraged to provide feedback or additional information on the mailing list. If no objections or further input are received, the draft will proceed to adoption, confirming previous in-room consensus.

## Decisions and Action Items

*   **Decision:** An informative Wiki page will be established on the CoRE GitHub organization to list and describe CoAP interface and resource type URIs/URNs used by different organizations/specifications.
*   **Decision:** The IANA scheme registry for CRIs will be adjusted to store unsigned numbers, with the negative mapping applied when the scheme ID is used as the first data item in a CRI.
*   **Decision:** The `HRE` document will be updated to include new CoAP options (`Proxy-CRI`, `Proxy-Scheme-Number`) and procedures for converting CRIs to CoAP options.

*   **Action Item:** Esco to start preparing a list of CoAP URIs/interfaces to populate the new Wiki page.
*   **Action Item:** Carsten to update the `HRE` document's Pull Request with the following:
    *   Analogous text for CRI to CoAP option conversion (similar to RFC 7252 sections 6.4/6.5).
    *   The new `Proxy-CRI` and `Proxy-Scheme-Number` options, incorporating the agreed-upon approach for unsigned scheme registry values.
    *   Considerations for location URIs with different schemes.
*   **Action Item:** Working Group participants to review the adoption call for the current document and provide any relevant input on the mailing list.

## Next Steps

*   The interim meeting scheduled in two weeks is likely to be cancelled unless critical and urgent issues arise.
*   Regular working group meetings are planned to resume in January.
*   Continue discussions on the mailing list regarding ongoing work and the adoption call.