Re: Informal Last Call for HTTP Preference Header

Martin Thomson <> Tue, 31 January 2012 22:44 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 93A3D21F85CD for <>; Tue, 31 Jan 2012 14:44:33 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -7.799
X-Spam-Status: No, score=-7.799 tagged_above=-999 required=5 tests=[AWL=2.800, BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id xEIfxEaDURYM for <>; Tue, 31 Jan 2012 14:44:32 -0800 (PST)
Received: from ( []) by (Postfix) with ESMTP id 8A58121F857A for <>; Tue, 31 Jan 2012 14:44:27 -0800 (PST)
Received: from lists by with local (Exim 4.69) (envelope-from <>) id 1RsMQh-0001bM-Bl for; Tue, 31 Jan 2012 22:43:59 +0000
Received: from ([]) by with esmtp (Exim 4.69) (envelope-from <>) id 1RsMPt-0001Yx-QC for; Tue, 31 Jan 2012 22:43:09 +0000
Received: from ([]) by with esmtp (Exim 4.72) (envelope-from <>) id 1RsMPr-00086Q-7q for; Tue, 31 Jan 2012 22:43:09 +0000
Received: by bkbzv3 with SMTP id zv3so627024bkb.2 for <>; Tue, 31 Jan 2012 14:42:41 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=iIFY/YziETAoP0bGRZeks4EyN2sDj75h9YBC9t1kxpU=; b=ZewkrML0s7b67Jd67gMFfxqcramUNxHU+JfohQN/5Qdi0PHAPq6GNYZcVjOXilVa02 ZX8pO2sHSYkppF5Qw2Da70bNYYj0+se5k55LsYrYNayeJvhCB8nnoEsOaASp2KUC6pFd OCxaZAe9stsZrKB+V6z4Mfa5G08QnrZsBTbgI=
MIME-Version: 1.0
Received: by with SMTP id l3mr11761382bkw.123.1328049761514; Tue, 31 Jan 2012 14:42:41 -0800 (PST)
Received: by with HTTP; Tue, 31 Jan 2012 14:42:41 -0800 (PST)
In-Reply-To: <>
References: <>
Date: Tue, 31 Jan 2012 14:42:41 -0800
Message-ID: <>
From: Martin Thomson <>
To: James Snell <>
Content-Type: text/plain; charset="UTF-8"
Received-SPF: pass client-ip=;;
X-W3C-Hub-Spam-Status: No, score=-2.7
X-W3C-Hub-Spam-Report: BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001
X-W3C-Scan-Sig: 1RsMPr-00086Q-7q d4af36f93abd6cdd6dcf9492aad9c2e7
Subject: Re: Informal Last Call for HTTP Preference Header
Archived-At: <>
X-Mailing-List: <> archive/latest/12283
Precedence: list
List-Id: <>
List-Help: <>
List-Post: <>
List-Unsubscribe: <>
Resent-Message-Id: <>
Resent-Date: Tue, 31 Jan 2012 22:43:59 +0000

I have only one real problem with the document as it stands.

Though the document requires that new preferences describe security
considerations, security considerations for the preferences included
are non-existent.  At a minimum, something needs to be said about the
security properties of the included preferences.

I suspect that the story is, in general:

A server could incur greater costs in attempting to comply with a
particular preference (for instance, the cost of providing a
representation in a response that would not ordinarily contain one; or
the commitment of resources necessary to track state for an
asynchronous response).  Unconditional compliance from a server could
allow the use of preferences for denial of service.  A server can
ignore an expressed preference to avoid expending resources that it
does not wish to commit.


On 31 January 2012 13:28, James Snell <> wrote:
> I just posted an update for the HTTP Prefer Header altering the
> intended status from "Informational" to "Standards Track". No
> additional changes were made. As I have not received any further
> technical input on the specification, I am issuing an *Informal* Last
> Call for comments before I request that it be kicked up the chain for
> review.
> Mark Nottingham has agreed to serve as the document shepherd for
> helping to move it forward.
> Current Draft:
> - James