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

Zhong Yu <zhong.j.yu@gmail.com> Wed, 16 January 2013 01:30 UTC

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Date: Tue, 15 Jan 2013 19:29:25 -0600
Message-ID: <CACuKZqFHMNK8yEiq1eJ-JyOk+gSL-Eh=CJyqUTjUSVJvmO55PQ@mail.gmail.com>
From: Zhong Yu <zhong.j.yu@gmail.com>
To: Nico Williams <nico@cryptonector.com>
Cc: Julian Reschke <julian.reschke@gmx.de>, Piotr Dobrogost <p@ietf.dobrogost.net>, ietf-http-wg@w3.org
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Subject: Re: Multiple header fields with the same field name - unwritten assumption about quoted commas in values?
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On Tue, Jan 15, 2013 at 7:02 PM, Nico Williams <nico@cryptonector.com> wrote:
> On Tue, Jan 15, 2013 at 6:53 PM, Julian Reschke <julian.reschke@gmx.de> wrote:
>> On 2013-01-16 00:38, Piotr Dobrogost wrote:
>>> I guess what Nico had in mind is if this subject could be clarified in
>>> 2.0 so that we won't have problems we have now in the future.
>>
>>
>> What problem, exactly?
>>
>> Given a valid message, you can combine header fields as specified in the
>> spec. But you don't have to.
>
> You shouldn't if you're a middlebox.
>

On the server side, it is a good idea to merge headers. There's no
point for a server framework to return multiple values for one header
name - application will have to merge them anyway before parsing.
(Java Servlet for example does not merge headers; it's a source of
bug; fortunately clients usually don't split headers)

On the client side, it's probably the same story (except Set-Cookie)

Zhong Yu

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