W3C home > Mailing lists > Public > ietf-http-wg@w3.org > July to September 2012

Re: Content-Length and 304

From: Phillip Hallam-Baker <hallam@gmail.com>
Date: Wed, 19 Sep 2012 22:05:17 -0400
Message-ID: <CAMm+LwisGtP9b8Z_XHcAoySRyTXdFE7ShrFY=qvjaqWp7UQ6cA@mail.gmail.com>
To: Zhong Yu <zhong.j.yu@gmail.com>
Cc: HTTP Working Group <ietf-http-wg@w3.org>
I think that the Content-Length handling is illogical. I can say that as I
originally proposed the header.

In the wake of keep-alive, Content-Length has two purposes; 1) content
meta-data and 2) specifying how much data is to follow.

My original intention was that it would only be the second. Then people
decided that HEAD methods should return the content-length and then things
got ugly.

Problem is that now you have to understand the error code semantics to get
the framing right. That seems like a design error to me.


On Wed, Sep 19, 2012 at 9:22 PM, Zhong Yu <zhong.j.yu@gmail.com> wrote:

> In the latest bis draft, a 304 response SHOULD set Content-Length
> equal to the length of the would-be payload body.
>
> ====
> http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-20#section-3.3.2
> 3.3.2. Content-Length
>
> ... a Content-Length header field SHOULD be sent to indicate the
> length of the payload body that ... would have been present had the
> request been an unconditional GET.
>
> ...In the case of a 304 response to a GET request, Content-Length
> indicates the size of the payload body that would have been sent in a
> 200 response.
> ====
>
>
> However, RFC2616 was not specific on the matter. If a server
> implementation always sets "Content-Length: 0" for 304 responses, it
> was acceptable. But now it becomes non-compliant under the new spec.
>
> Is this new requirement really necessary? Who would benefit from it?
>
> According to the reasoning of
>
> ====
> http://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional-20#section-4.1
> 4.1. 304 Not Modified
> Since the goal of a 304 response is to minimize information transfer
> when the recipient already has one or more cached representations, the
> response SHOULD NOT include representation metadata other than the
> above listed fields
> ====
>
> we SHOULD NOT include Content-Length in 304 responses either.
>
> I think the meaning of Content-Length is confusing enough, in the case
> of 204/304 response, it's better to require that
> 1. server SHOULD NOT set Content-Length
> 2. client MUST ignore Content-Length
>
> Zhong Yu
>
>


-- 
Website: http://hallambaker.com/
Received on Thursday, 20 September 2012 02:05:44 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 20 September 2012 02:05:51 GMT