Subject: [Ietf-message-headers] Provisional registration of 5 X-Device-* HTTP Header fields for use in content transformation guidelines

From: Francois Daoust <[email-masked]>
Date: Thu, 09 Jul 2009 12:06:31 +0200

Hi,

Please find below the registration template for 5 HTTP header fields the 
W3C Mobile Web Best Practices Working Group would like to provisionally 
register for use in the "Guidelines for Web Content Transformation 
Proxies" specification it is currently working on.

Note on the presence of the "X-" prefix: names were chosen on the basis 
that there are a already existing and deployed convention. Since there 
is no easy way to transition out of a situation where an "X-" prefix has 
been used for other purpose than a purely experimental one, the W3C 
Mobile Web Best Practices Working Group acknowledges that these HTTP 
header field names are already in use and requests that the "X-" prefix 
be (exceptionally) kept.

-----
Header field names:
X-Device-User-Agent (request header)
X-Device-Accept (request header)
X-Device-Accept-Charset (request header)
X-Device-Accept-Encoding (request header)
X-Device-Accept-Language (request header)

Applicable protocol:
http

Status:
provisional

Author/Change controller:
W3C Mobile Web Best Practices Working Group
http://www.w3.org/2005/MWI/BPWG/

Specification document(s):
http://www.w3.org/2005/MWI/BPWG/Group/TaskForces/CT/editors-drafts/Guidelines/latest 

(Editor's Draft)
http://www.w3.org/TR/ct-guidelines/ (Working Draft)

See section "4.1.5.5 Original Header Fields" in the documents.
-----

I will submit the above template to the designated IANA e-mail address 
beginning of August, unless some explicit disagreement is made on this list.

Regards,

On behalf of the W3C Mobile Web Best Practices Working Group,
Francois Daoust,
W3C Staff Contact for the group.

---

From: Francois Daoust <[email-masked]>
Date: Fri, 10 Jul 2009 17:34:36 +0200

Hi Graham,

The situation the Mobile Web Best Practices working group is trying to 
address is one where different vendors used different HTTP header field 
conventions (all starting with 'X-') for the same use in their proxies, 
requiring content providers to support the different names when they 
wanted to do things properly. What the working group would like to do is 
to shrink the list of existing conventions to one and only one 
convention, but would prefer not to introduce any new convention (be it 
the last one) for that to happen. The 'X-Device-foo' format is the most 
commonly used format in the list based on the group's experience, and 
thus the chosen one.

That said, I have nothing against provisional registration of both 
forms. I add the topic to the working group's agenda for discussion. I 
suppose that, in any case, if we register the 'X-Device-User-Agent' 
header field, the 'Device-User-Agent' header field de facto would become 
"unavailable", not to trigger any confusion.

Francois.

Graham Klyne wrote:
> Concerning the use of X- headers.
> 
> A similar situation existed with the X-Archived-At header field [1].  
> When that proposal went to standard/recommendation, the 'X-' was dropped 
> for the permanent registration [2], but the 'X-' version was retained in 
> the provisional registry [3], marked as 'Deprecated'.
> 
> Assuming that you intend your specification to proceed to REC, I would 
> suggest a similar approach here.  In which case, you may wish to 
> consider provisional registration of both forms.
> 
> (The provisional header registry was intended, in part, to address 
> unsatisfactory aspects of the 'X-' naming convention illustrated by 
> cases like this.)
> 
> [1] http://www.rfc-editor.org/rfc/rfc5064.txt
> [2] http://www.iana.org/assignments/message-headers/perm-headers.html
> [3] http://www.iana.org/assignments/message-headers/prov-headers.html
> 
> #g
> -- 
> 
> 
> Francois Daoust wrote:
>> Hi,
>>
>> Please find below the registration template for 5 HTTP header fields 
>> the W3C Mobile Web Best Practices Working Group would like to 
>> provisionally register for use in the "Guidelines for Web Content 
>> Transformation Proxies" specification it is currently working on.
>>
>> Note on the presence of the "X-" prefix: names were chosen on the 
>> basis that there are a already existing and deployed convention. Since 
>> there is no easy way to transition out of a situation where an "X-" 
>> prefix has been used for other purpose than a purely experimental one, 
>> the W3C Mobile Web Best Practices Working Group acknowledges that 
>> these HTTP header field names are already in use and requests that the 
>> "X-" prefix be (exceptionally) kept.
>>
>>
>> -----
>> Header field names:
>> _______________________________________________
>> Ietf-message-headers mailing list
>> [email-masked]
>> https://www.ietf.org/mailman/listinfo/ietf-message-headers
>>
>

---

From: SM <[email-masked]>
Date: Fri, 10 Jul 2009 09:15:59 -0700

Hi Francois,
At 08:34 10-07-2009, Francois Daoust wrote:
>The situation the Mobile Web Best Practices working group is trying 
>to address is one where different vendors used different HTTP header 
>field conventions (all starting with 'X-') for the same use in their 
>proxies, requiring content providers to support the different names 
>when they wanted to do things properly. What the working group would 
>like to do is to shrink the list of existing conventions to one and 
>only one convention, but would prefer not to introduce any new 
>convention (be it the last one) for that to happen. The 
>'X-Device-foo' format is the most commonly used format in the list 
>based on the group's experience, and thus the chosen one.

I'll encourage you to adopt Graham's suggestion of moving to 
"Device-foo" or any other valid name that does not start with 
"X-".  These "X-" headers are generally for private use where the 
interpretation is by private agreement.  There are people outside the 
group that might use that header field for other purposes and they 
are unlikely to look it up in the registry.  If your working group 
already agrees on having one convention, it is better to do away with the "X-".

>forms. I add the topic to the working group's agenda for discussion. 
>I suppose that, in any case, if we register the 
>'X-Device-User-Agent' header field, the 'Device-User-Agent' header 
>field de facto would become "unavailable", not to trigger any confusion.

You'll have to register that header field as well.

Regards,
-sm