Draft: draft-ietf-masque-h3-datagram

Commentary: Section 1 . " When the underlying transport protocol supports unreliable delivery ( such as when the QUIC DATAGRAM extension is available in HTTP/3 ) , they can use that capability . " " This document also describes the HTTP Capsule Protocol in Section 3 , to allow conveyance of HTTP Datagrams when the QUIC DATAGRAM frame is unavailable or undesirable , such as when earlier versions of HTTP are in use . " To me there is a bit of mismatch between these two sentences and what HTTP/3 is prior to this extension . The first indicate that datagram support is a capability of the underlying transport for the HTTP version but then link it hard to HTTP/3 . While the HTTP/3 support is dependent on this extension in addition to a QUIC stack having Datagram support . While the second takes it as a property of the HTTP version , where it is assumed that earlier version ca n't support this , i.e. those that are defined to use TCP only . Technically a HTTP/3 endpoint with a QUIC stack without datagram support can use capsules and this document does not require an endpoint to support QUIC datagram . And the second statement should likely use a statement saying like … unavailable or undesirable , such as when TCP is used as transport protocol as with HTTP/1.x and HTTP/2 . 
 Fair point , HTTP 1 and 2 do n't strictly require TCP either . I think we can tweak these opening paragraphs a little to be more consistent and clear . 
 SGTM 
 Looks great modulo one tweak
In datagrams, this document describes HTTP Datagrams, a convention
that supports the bidirectional and possibly multiplexed exchange of
data inside an HTTP connection.  While HTTP datagrams are associated
with HTTP requests, they are not part of message content; instead,
they are intended for use by HTTP extensions (such as the CONNECT
method), and are compatible with all versions of HTTP.  When the
underlying transport protocol supports unreliable delivery (such as
when the QUIC DATAGRAM extension is available in HTTP/3), they can
use that capability.
This document also describes the HTTP Capsule Protocol in capsule, to
allow conveyance of HTTP Datagrams when the QUIC DATAGRAM frame is
unavailable or undesirable, such as when earlier versions of HTTP are
in use.
In datagrams, this document describes HTTP Datagrams, a convention
that supports the bidirectional and possibly multiplexed exchange of
data inside an HTTP connection.  While HTTP datagrams are associated
with HTTP requests, they are not part of message content; instead,
they are intended for use by HTTP extensions (such as the CONNECT
method), and are compatible with all versions of HTTP.
When HTTP is running over a transport protocol that supports
unreliable delivery (such as when the QUIC DATAGRAM extension is
available to HTTP/3), HTTP Datagrams can use that capability.
This document also describes the HTTP Capsule Protocol in capsule, to
allow conveyance of HTTP Datagrams using reliable delivery.  This
addresses HTTP/3 cases where use of the QUIC DATAGRAM frame is
unavailable or undesirable, or where the transport protocol only
provides reliable delivery, such as with HTTP/1 or HTTP/2 over TCP.