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Re: Multiple header fields with the same field name - unwritten assumption about quoted commas in values?

From: Karl Dubost <karld@opera.com>
Date: Wed, 9 Jan 2013 17:10:24 +0900
Message-Id: <9ECBD5AA-2704-4355-9A58-0A4242573E64@opera.com>
Cc: ietf-http-wg@w3.org
To: Piotr Dobrogost <p@ietf.dobrogost.net>

Le 9 janv. 2013 à 09:28, Piotr Dobrogost a écrit :
> In http://trac.tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-21#section-3.2
> one reads
> "Multiple header fields with the same field name MUST NOT be sent in a message unless the entire field value for that header field is defined as a comma-separated list [i.e., #(values)]."

To add to Piotr comment and give a bit of context: 

Let's imagine a situation where I want to send multiple qualified Link: such as:

   Link: </2012/07/26/csstests/csshttplink.css>;rel=stylesheet
   Link: </>;rel=next

According to the quoted paragraph, The sender (server in this case) MUST not send that but 

   Link: </2012/07/26/csstests/csshttplink.css>;rel=stylesheet, </>;rel=next

Is it a correct understanding?

Then there are cases where some Headers have values with commas. Am I correct?


> Because commas (",") are used as a generic delimiter between field-
> values, they need to be treated with care if they are allowed in the
> field-value's payload.  Typically, components that might contain a
> comma are protected with double-quotes using the quoted-string ABNF
> production (Section 3.2.4 of [Part1]).
> For example, a textual date and a URI (either of which might contain
> a comma) could be safely carried in field-values like these:
>   Example-URI-Field: "http://example.com/a.html,foo",
>                         "http://without-a-comma.example.com/"
>   Example-Date-Field: "Sat, 04 May 1996", "Wed, 14 Sep 2005"
> Note that double-quote delimiters almost always are used with the
> quoted-string production; using a different syntax inside double-
> quotes will likely cause unnecessary confusion.

Karl Dubost - http://dev.opera.com/
Developer Relations, Opera Software
Received on Wednesday, 9 January 2013 15:35:09 UTC

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