Re: WGLC: p2 MUSTs

"Roy T. Fielding" <> Sun, 04 August 2013 01:50 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 248BC21F995B for <>; Sat, 3 Aug 2013 18:50:44 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -10.349
X-Spam-Status: No, score=-10.349 tagged_above=-999 required=5 tests=[AWL=0.250, BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id o0OpUuuT0OHg for <>; Sat, 3 Aug 2013 18:50:32 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id 4E30021E8084 for <>; Sat, 3 Aug 2013 18:50:31 -0700 (PDT)
Received: from lists by with local (Exim 4.72) (envelope-from <>) id 1V5nRM-0002ha-NP for; Sun, 04 Aug 2013 01:49:00 +0000
Resent-Date: Sun, 04 Aug 2013 01:49:00 +0000
Resent-Message-Id: <>
Received: from ([]) by with esmtp (Exim 4.72) (envelope-from <>) id 1V5nR9-0002gj-42 for; Sun, 04 Aug 2013 01:48:47 +0000
Received: from ([] by with esmtp (Exim 4.72) (envelope-from <>) id 1V5nR7-0002iV-LQ for; Sun, 04 Aug 2013 01:48:46 +0000
Received: from (localhost []) by (Postfix) with ESMTP id 10E48428076; Sat, 3 Aug 2013 18:48:24 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed;; h=subject :mime-version:content-type:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to;; bh=DNvN/4UWsQBT1zy2f6sqHmbK+N8=; b=5liipSZp7rkn1nk7GZw0pA3ylncQ YZ2fj1wa7Tn3CV5cCVPhrIXDB7nQXvZK7KVa5qBgU8esIsdo0fcAKCEjudYT9Yy0 Gr+HBJAgZQSw1Gig/eS4OBqU7zA9yYV5MXv5fBE+RClOS04RiW7SIXyCNpINSnwB Ysf+GHCP3Blxwrg=
Received: from [] ( []) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: by (Postfix) with ESMTPSA id CDD44428075; Sat, 3 Aug 2013 18:48:23 -0700 (PDT)
Mime-Version: 1.0 (Apple Message framework v1283)
Content-Type: text/plain; charset=windows-1252
From: "Roy T. Fielding" <>
In-Reply-To: <>
Date: Sat, 3 Aug 2013 18:48:22 -0700
Content-Transfer-Encoding: quoted-printable
Message-Id: <>
References: <> <>
To: Alex Rousskov <>
X-Mailer: Apple Mail (2.1283)
Received-SPF: none client-ip=;;
X-W3C-Hub-Spam-Status: No, score=-0.1
X-W3C-Hub-Spam-Report: DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_NONE=-0.0001
X-W3C-Scan-Sig: 1V5nR7-0002iV-LQ 763740c5cbd8b35497fb8eda96489e41
Subject: Re: WGLC: p2 MUSTs
Archived-At: <>
X-Mailing-List: <> archive/latest/19050
Precedence: list
List-Id: <>
List-Help: <>
List-Post: <>
List-Unsubscribe: <>

On Apr 30, 2013, at 1:46 PM, Alex Rousskov wrote:

>> The CONNECT method requests that the recipient establish a tunnel to
>> the destination origin server [...], until the connection is closed.
> The "until the connection is closed" part is misleading and inaccurate.
> There are two connections in a CONNECT tunnel: (a) between a CONNECT
> sender and CONNECT recipient and (2) between CONNECT recipient the the
> next HTTP hop. The tunnel termination condition is rather complex and is
> detailed later in the same section. It may be a good idea to drop the
> "until..." part. At least I cannot suggest a way to describe it
> correctly as an ending of an already long sentence :-).

Changed to "until the tunnel is closed".

>> When a tunnel intermediary detects that either side has closed its
>> connection, any outstanding data that came from that side will first
>> be sent to the other side and then the intermediary will close both
>> connections. If there is outstanding data left undelivered, that data
>> will be discarded.
> These "will"s should be rephrased as intermediary MUSTs IMO. I also
> suggest moving them higher, before the informal risk discussion.

Moved, fixed, and rephrased to "A tunnel is closed when ..."

>> A client MUST NOT send header fields in a TRACE request containing
>> sensitive data
> The above rule seems too onerous to proxies. Replace "MUST NOT send"
> with "MUST NOT generate"?


>> Use of the 100 (Continue) Status
>> Requirements for HTTP/1.1 clients:
>> ...
>> Requirements for HTTP/1.1 proxies:
> Should we explicitly exclude proxies from the first group of
> requirements by saying "Requirements for user agents" instead of
> "Requirements for clients"?

No, the first set applies to proxies that want to use 100-continue
for their own reasons.

>> MUST contain an updated Max-Forwards field with a value decremented by one (1).
> A lot of proxies violate this MUST because they cannot grok and, hence,
> cannot decrement large integer values. Interoperability problems might
> happen when a client generates Max-Forwards with a maximum value it can
> store (e.g., to count the number of hops to the origin server) but the
> proxy cannot store such a large value (e.g., 64bit vs 32bit).
> Perhaps we can relax this rule by allowing proxies to decrement by "at
> least one", so that a huge value can be replaced with the maximum value
> the proxy can represent?

Changed to

  If the received Max-Forwards value is greater than zero,
  the intermediary MUST generate an updated Max-Forwards field
  in the forwarded message with a field-value that is the lesser of:
  a) the received value decremented by one (1), or
  b) the recipient's maximum supported value for Max-Forwards.

>> A client MUST be prepared to accept one or more 1xx
> Drop "be prepared" to demand acceptance rather than preparedness?

Fixed in prior commit.

>> Proxies MUST forward 1xx responses, unless the connection between the
>> proxy and its client has been closed,
> This "unless" clause should be dropped as implied. Otherwise, we would
> have to add it to every "MUST forward" requirement! :-)


>> A sender MUST generate the IMF-fixdate format when sending an
>> HTTP-date value in a header field.
> Please polish to remove the implication that proxies must fix dates when
> forwarding HTTP-date values. For example: "A sender MUST use the
> IMF-fixdate format when generating a header field containing an
> HTTP-date value".
> Or perhaps simply: "A sender MUST generate HTTP-date values in the
> IMF-fixdate format".


> And here is a list of requirements that are missing an explicit actor on
> which the requirement is placed. Most of these should be easy to
> rephrase to place the requirement on the intended actor (e.g., "A proxy
> MUST" instead of "header field MUST":
>> the content codings MUST be listed in the order in which they were applied


>> then the resource MUST disable or disallow that action

resource owner

>> The Expect header field MUST be forwarded


>> the forwarded message MUST contain an updated Max-Forwards field

Fixed above.

>> The Max-Forwards header field MAY be ignored for all other request methods. 


>> a response with an unrecognized status code MUST NOT be cached.


Committed in