Re: draft-ietf-quic-http-29, "1.1. Prior versions of HTTP"

Paul Vixie <> Fri, 12 June 2020 18:01 UTC

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From: Paul Vixie <>
To: Julian Reschke <>, Robin MARX <>,
Cc: IETF QUIC WG <>, Mike Bishop <>
Subject: Re: draft-ietf-quic-http-29, "1.1. Prior versions of HTTP"
Date: Fri, 12 Jun 2020 18:01:13 +0000
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On Friday, 12 June 2020 15:55:36 UTC Mike Bishop wrote:
> Robin has almost the intended reading.  One request/response at a time, in
> each direction.  So while you might send several requests in sequence
> before getting any responses back, each direction is always either in the
> middle of exactly one message, or between messages.

the terminology here is easily confusable. in HTTP/1.1, a greedy responder can 
parse pipelined requests and start the work associated with each. however, the 
answers have to come back in order. this "head of line blocking" imposes 
response serialization, and HTTP/3 avoids this.

one way to word this is to call out serialization of both requests and 
responses, and ordering of responses, as limits of HTTP/1.1 that HTTP/3 is 
designed to overcome. wording like "at the same time" is less clear.