Markdown Version | Session Recording

Session Date/Time: 23 Mar 2022 12:00

taps

Summary

The taps working group session provided updates on existing documents, discussed the upcoming Working Group Last Call (WGLC) for the Implementation draft, and presented a new QUIC mapping document. There was strong support for adopting the QUIC mapping, and a proposal to add a new charter milestone for general protocol mapping documents was introduced. Additionally, a presentation on the PanAPI system, a TAPS-like transport system developed for SCION, offered valuable feedback on the TAPS API design, particularly concerning property handling and the visibility of implementation flexibility.

Key Discussion Points

• Chairs' Update and Document Status:
  • Since IETF 111, the working group has held six interim meetings, focusing on resolving review comments.
  • The Architecture and API documents have concluded WGLC and received ART and internal deep reviews. The API document has only two open issues remaining.
  • The Implementation draft is nearing WGLC, with a handful of open issues still to be resolved.
  • An issue with author lists exceeding the recommended five for RFCs was resolved by some contributors electing to remove their names; justification has been prepared for the IESG for documents still above the limit.
• Document Release Strategy:
  • A suggestion was made to release the Architecture and Interface documents for IESG/IETF last call sooner, rather than waiting for the Implementation draft, to distribute the review workload and allow earlier feedback. The chairs acknowledged this for consideration.
• Reviewers for Implementation Draft WGLC:
  • A call for non-author reviewers for the Implementation draft's WGLC was made, emphasizing the need for fresh eyes to check for readability, consistency, and comprehension, rather than deep expertise.
  • Ideally, reviews should be completed within four weeks after IETF 113, around the time of the next interim. No volunteers stepped forward during the session.
• Working Group Schedule:
  • The working group plans monthly interims.
  • It was reaffirmed that the group will meet every other IETF, meaning no meeting at IETF 114, with the next IETF session planned for IETF 115.
• Proposal for Protocol Mapping Milestone:
  • A new milestone for the charter was proposed: "producing one or more protocol mapping documents." These documents would illustrate how higher-layer protocols or transport protocols would utilize the TAPS API. This would require Area Director approval.
  • HTTP was suggested as another protocol that could benefit from a mapping document due to its unclear mapping to TAPS.
• QUIC Mapping Document Presentation (Tommy Pauly):
  • Tommy Pauly presented a new draft (draft-pauly-taps-quic-mapping-00), providing an example of how TAPS can be used with QUIC.
  • The document defines what happens when TAPS API calls are used with QUIC, focusing on establishment, tear-down, and data transfer.
  • Key Mapping: A TAPS Connection maps to a QUIC Stream, and a TAPS Connection Group maps to a QUIC Connection.
  • It details how TAPS functions like Initiate, Cloning, Sending, Receiving, Closing, and Aborting map to QUIC stream and connection operations, including 0-RTT support for Initiate.
  • Feedback:
    • Suggestions to add a high-level summary of the mapping's use cases ("what is this good for / not good for") and to include QUIC datagram mapping within the document for completeness.
    • Discussion on how TAPS handles QUIC's STOP_SENDING frames; it's not a general TAPS API feature but could be exposed as protocol-specific metadata.
    • Confirmation that the mapping is sufficient for implementing an HTTP/3 client/server, possibly with protocol-specific metadata for stream IDs.
    • Clarification that TAPS Connection Groups can encompass both reliable (streams) and unreliable (datagrams) flows on the same underlying QUIC connection.
    • A need for "background information and surveys" within mapping documents, not just direct mappings, to address nuances.
• PanAPI System Presentation (Thorben Krüger):
  • Thorben Krüger presented PanAPI, a TAPS-like transport system developed for SCION (a future internet architecture focusing on path awareness).
  • PanAPI uses the TAPS API as its front-end and is implemented in Go, with a web-based scripting backend. It supports TCP, UDP, QUIC, and UDP/QUIC over SCION.
  • Design Choices/Departures from TAPS:
    • Explicit SCION support added.
    • No Event System: PanAPI leverages Go's native concurrency model (blocking calls, background dispatching for asynchronicity), finding an event-based system unintuitive for Go developers.
    • Strongly Typed Objects for Properties: A design choice to catch errors at compile time, which proved challenging.
  • Most TAPS concepts map well to SCION, but "active probing" (pinging alternative paths for latency) is a SCION-specific feature without a direct TAPS equivalent.
  • Feedback for TAPS API:
    • Property Stages: The TAPS drafts do not explicitly distinguish between mutable "preference" properties (settings) and converged "truth value" properties (results of selection). This dynamic behavior is difficult for statically-typed languages and could benefit from clearer conceptual distinction in the specification.
    • Event System Visibility: The current documentation on the flexibility to implement TAPS without an explicit event system (mentioned in an appendix) should be more prominently placed in the main document.

Decisions and Action Items

• Decision: The working group expressed strong support for adopting the QUIC Mapping document (draft-pauly-taps-quic-mapping-00).
• Action Item: Aaron Falk (chair) will solicit non-author reviewers for the Implementation draft WGLC via the mailing list.
• Action Item: The chairs will seek Area Director approval for the proposed new charter milestone for protocol mapping documents.
• Action Item: Tommy Pauly to consider incorporating QUIC datagram mapping and a high-level summary of the mapping's specific use cases into the QUIC mapping document.
• Action Item: Brian Trammell to address GitHub issue #1009, clarifying that TAPS implementations are not strictly required to be event-based, aiming for a PR by the end of the IETF break.
• Action Item: Rhys Engert (chair) to ensure the QUIC mapping document is properly associated as a related document in the DataTracker.

Next Steps

• The Implementation draft WGLC is planned to open after IETF 113, following resolution of current issues and securing reviewers.
• Further discussion on potential protocol mapping documents (e.g., HTTP) is encouraged.
• The next working group interim meeting is tentatively scheduled for early May.