Subject: [V3] RIPT Use Cases

From: Bernard Aboba <[email-masked]>
Date: Wed, 13 May 2020 18:42:51 -0700

The W3C is currently looking at the use cases discussed in the IETF
WEBTRANS and RIPT BOFs, in an effort to develop a W3C WebTransport charter,
as well as to understand what other work might need to be done on the W3C
side.

Overall, the goal discussed in the RIPT BOF of "making it as easy to bring
up a cloud-based RTC service as it is to bring up a Web service" seems to
be resonating.  However, the question has arisen as to whether WebTransport
API and protocols as currently proposed satisfy all the needs discussed in
the RIPT BOF.

Initial discussions seem to indicate that there are potential use cases
described in the RIPT BOF that go beyond the functionality proposed in the
WebTransport protocols. In particular:

1. The goal of "leveraging Web-based cloud infrastructure" was not achieved
by WebSockets, in part because of operational issues such as difficulties
in leveraging CDNs and operational issues such as load balancing and
draining of existing connections from endpoints that need to be removed
from service.  So the question is whether WebTransport will inevitably
inherit some of those problems, even if it does support
unreliable/unordered transport.

2. Slides in the RIPT BOF showed an HTTP/3 GET being responded to with
HTTP/3 datagrams. This is not something that is contemplated in
WebTransport (or is currently in discussion in HTTPBIS, as far as I am
aware).  But it does seem appealing for use cases such as a "moderate
latency" streaming service that attempts to reduce video stalls by sending
"discardable" frames using QUIC datagrams.