Re: [quicwg/base-drafts] VarInt all the HTTP things (#2437)

Martin Thomson <> Mon, 11 February 2019 00:07 UTC

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Subject: Re: [quicwg/base-drafts] VarInt all the HTTP things (#2437)
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martinthomson approved this pull request.

> @@ -303,15 +303,16 @@ specify a value of zero for the QUIC transport parameter
 ## Unidirectional Streams
 Unidirectional streams, in either direction, are used for a range of purposes.
-The purpose is indicated by a stream type, which is sent as a single byte header
-at the start of the stream. The format and structure of data that follows this
-header is determined by the stream type.
+The purpose is indicated by a stream type, which is sent as a variable-length
+integer at the start of the stream. The format and structure of data that

The word "header" appears in the figure title.

> @@ -384,11 +387,11 @@ client MUST treat this as a connection error of type HTTP_DUPLICATE_PUSH.
 ### Reserved Stream Types {#stream-grease}
-Stream types of the format `0x1f * N` are reserved to exercise the requirement
-that unknown types be ignored. These streams have no semantic meaning, and can
-be sent when application-layer padding is desired.  They MAY also be sent on
-connections where no request data is currently being transferred. Endpoints MUST
-NOT consider these streams to have any meaning upon receipt.
+Stream types of the format `0x1f * N` for non-zero values of N are reserved to

Rather than grapple with the 0 value, why not 0x1f*N+0x21 or something like that?

> @@ -1868,7 +1861,9 @@ use the full 32-bit space.  Settings ported from HTTP/2 might choose to redefine
 the format of their settings to avoid using the 62-bit encoding.
 Settings need to be defined separately for HTTP/2 and HTTP/3. The IDs of
-settings defined in {{!RFC7540}} have been reserved for simplicity. See
+settings defined in {{!RFC7540}} have been reserved for simplicity.  Note that
+the settings identifier space in HTTP/3 is substantially larger (62 bits versus
+16 bits), so many HTTP/3 settings have no equivalent HTTP/2 code point. See

#2443 (that feature that creates an issue is nice, but it should leave a tombstone so that people know not to reply).

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