Re: Question about resource and representation

Amos Jeffries <squid3@treenet.co.nz> Mon, 14 November 2016 05:45 UTC

Return-Path: <ietf-http-wg-request+bounce-httpbisa-archive-bis2juki=lists.ie@listhub.w3.org>
X-Original-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Delivered-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 09EA6129543 for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Sun, 13 Nov 2016 21:45:39 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8.398
X-Spam-Level:
X-Spam-Status: No, score=-8.398 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.001, RCVD_IN_DNSWL_HI=-5, RP_MATCHES_RCVD=-1.497, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 2uutcEi_sSFG for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Sun, 13 Nov 2016 21:45:36 -0800 (PST)
Received: from frink.w3.org (frink.w3.org [128.30.52.56]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 14DF91295C4 for <httpbisa-archive-bis2Juki@lists.ietf.org>; Sun, 13 Nov 2016 21:45:35 -0800 (PST)
Received: from lists by frink.w3.org with local (Exim 4.80) (envelope-from <ietf-http-wg-request@listhub.w3.org>) id 1c6A1j-0001Cj-FR for ietf-http-wg-dist@listhub.w3.org; Mon, 14 Nov 2016 05:41:55 +0000
Resent-Date: Mon, 14 Nov 2016 05:41:55 +0000
Resent-Message-Id: <E1c6A1j-0001Cj-FR@frink.w3.org>
Received: from mimas.w3.org ([128.30.52.79]) by frink.w3.org with esmtps (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from <squid3@treenet.co.nz>) id 1c6A1e-0001B0-4U for ietf-http-wg@listhub.w3.org; Mon, 14 Nov 2016 05:41:50 +0000
Received: from [121.99.228.82] (helo=treenet.co.nz) by mimas.w3.org with esmtp (Exim 4.84_2) (envelope-from <squid3@treenet.co.nz>) id 1c6A1X-00061d-Ou for ietf-http-wg@w3.org; Mon, 14 Nov 2016 05:41:44 +0000
Received: from [192.168.20.251] (unknown [121.98.41.216]) by treenet.co.nz (Postfix) with ESMTP id 731ECE6EA7 for <ietf-http-wg@w3.org>; Mon, 14 Nov 2016 18:41:09 +1300 (NZDT)
To: ietf-http-wg@w3.org
References: <CAFT+Tg_UcBbHD1yz=26FUa6i6Ja=Z2O5UoJa_id4-MYM-X9iEA@mail.gmail.com>
From: Amos Jeffries <squid3@treenet.co.nz>
Message-ID: <6b7ac432-7027-0ac8-541c-9e5d51b2f5b9@treenet.co.nz>
Date: Mon, 14 Nov 2016 18:41:08 +1300
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <CAFT+Tg_UcBbHD1yz=26FUa6i6Ja=Z2O5UoJa_id4-MYM-X9iEA@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Received-SPF: pass client-ip=121.99.228.82; envelope-from=squid3@treenet.co.nz; helo=treenet.co.nz
X-W3C-Hub-Spam-Status: No, score=-4.3
X-W3C-Hub-Spam-Report: AWL=-1.237, BAYES_00=-1.9, RDNS_NONE=0.793, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, W3C_AA=-1, W3C_WL=-1
X-W3C-Scan-Sig: mimas.w3.org 1c6A1X-00061d-Ou 01bec0cef09b4e6b014d6f0667b2591a
X-Original-To: ietf-http-wg@w3.org
Subject: Re: Question about resource and representation
Archived-At: <http://www.w3.org/mid/6b7ac432-7027-0ac8-541c-9e5d51b2f5b9@treenet.co.nz>
Resent-From: ietf-http-wg@w3.org
X-Mailing-List: <ietf-http-wg@w3.org> archive/latest/32886
X-Loop: ietf-http-wg@w3.org
Resent-Sender: ietf-http-wg-request@w3.org
Precedence: list
List-Id: <ietf-http-wg.w3.org>
List-Help: <http://www.w3.org/Mail/>
List-Post: <mailto:ietf-http-wg@w3.org>
List-Unsubscribe: <mailto:ietf-http-wg-request@w3.org?subject=unsubscribe>

On 14/11/2016 6:08 p.m., Yi, EungJun wrote:
> Hi,
> 
> 
> According to RFC 7231, a representation is a state of a given resource
> 
> 
>    For the purposes of HTTP, a "representation" is information that is
>    intended to reflect a past, current, or desired state of a given
>    resource, in a format that can be readily communicated via the
>    protocol, and that consists of a set of representation metadata and a
>    potentially unbounded stream of representation data.
> 
> 
> and a payload in a POST request is also a representation.
> 
> 
>    The POST method requests that the target resource process the
>    representation enclosed in the request according to the resource's
>    own specific semantics.
> 
> 
> Then what is the resource which the representation enclosed in the
> POST request reflects? I think the representation may not reflect a
> state of the target resource for the POST request.
> 

For POST there are three resources involved;

 1) the server script/app receiving the POST is a resource (target
resource in the POST URL)

 2) the processing states that scripts code logic (semantics) can go
through.

 3) the resulting server data state is a resource (response resource).


The payload of the POST relates most directly to (2). It is not a
physical "thing" resource, just a logical set of processing states.



Just like other messages the payload of a POST could be in either
plain-text or compressed form. But as long as the uncompressed data is
the same set of values the two representations result in the same
logical processing by the server.


HTH
Amos