Session Date/Time: 20 Mar 2025 08:00

webtrans

Summary

This meeting covered the progress of the W3C web transport working group, remaining issues in web transport, and potential reverse proxy use cases for web transport. Key discussions revolved around the necessity of course pre-flight, service certificate hashes, adding headers, protocol negotiation, flow control, pooling, and stream ID. The group agreed to land negotiation of flow control and revisit the decision after gaining implementation experience. It also deferred a decision on requiring final size fields until after the Madrid meeting.

Key Discussion Points

W3C Web Transport Update: The W3C working group has extended its charter, published a timetable for release, and is targeting candidate recommendation in the next month or two. Major updates include treating redirection as a network error, adding an "at send capacity" flag, adding a protocols constructor argument for subprotocol negotiation, and adjusting the estimated send rate definition. A new "datagrams create writable" API was added for assigning independent send priority to parallel flows of datagrams.
Course Pre-flight & Headers: Discussion on whether course pre-flight becomes necessary if ad hoc headers are allowed. The group acknowledged the tie between the course question and the header question.
Service Certificate Hashes: Contentious issue regarding removing support for service certificate hashes. The group hoped hallway conversations would help resolve this.
Adding Headers: Request for support for adding headers. Some argued that headers are useful for pre-negotiating things before any application data. Concerns were raised about potential engagement with Fetch and implications for pre-flighting.
Protocol Negotiation: Agreement on making subprotocol negotiation optional.
Flow Control & Pooling: Extensive discussion about flow control. Concerns were raised about implementation complexity and potential deadlocks with two layers of flow control. The group discussed making flow control truly optional, with pooling being tied to it.
Hidden origins: Potential benefits of the "hidden origins" concept. The group recognized the potential and asked whether a simpler reverse proxy would be better.
Stream ID: Potential issue in using stream IDs in different layers. There was not appetite for making any changes to the design.
Final Size: Implementations are expected to be able to report the final size if the stream gets closed.

Decisions and Action Items

Flow Control: Land negotiation of flow control and revisit the decision after gaining implementation experience.
- Action Item: Eric to write a PR for negotiating flow control.
Final Size: Defer a decision on requiring final size fields until after the Madrid meeting.
Sub Protocol: Confirmed the sub protocol negotiation is optional
- Action Item: David to verify the sub protocol and determine if there are editorial items that need addressing.
PRs: Editorial PR to Alan
INA: Assigned to MT to create an INA section
Interop: Virtual interop before the Madrid meeting.
- Action Item: Chairs to schedule a virtual interop before the Madrid meeting.

Next Steps

Implementers to gain experience with flow control and pooling.
Discuss flow control and pooling implementation experiences at the Madrid meeting.
Cut a new implementation draft with the negotiated flow control.
Schedule a virtual interop.
Address remaining editorial issues in H2 and H3.