Subject: Warn header (P6) vs RFC2047 encoding

From: Julian Reschke <[email-masked]>
Date: Thu, 23 Jul 2009 12:22:50 +0200

Hi,

I noticed that P6 still has a normative dependency on RFC 2047: for 
encoding non-ISO-8859-1 characters in Warn headers:

"The warn-text SHOULD be in a natural language and character set that is 
most likely to be intelligible to the human user receiving the response. 
This decision can be based on any available knowledge, such as the 
location of the cache or user, the Accept-Language field in a request, 
the Content-Language field in a response, etc. The default language is 
English and the default character set is ISO-8859-1 ([ISO-8859-1]).

If a character set other than ISO-8859-1 is used, it MUST be encoded in 
the warn-text using the method described in [RFC2047]." -- 
<http://greenbytes.de/tech/webdav/draft-ietf-httpbis-p6-cache-latest.html#rfc.section.3.6.p.9>

I think this should be dropped the same way we already did it for the 
Reason Phrase (see <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/94>).

Best regards, Julian

---

From: Henrik Nordstrom <[email-masked]>
Date: Thu, 23 Jul 2009 21:27:07 +0200

> Reason Phrase (see <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/94>).

Reason Phrase is different as this generally is not intended to be
displayed in user agents other than for debugging/tracing/status
indications, while Warning is really intended to be displayed to the
user with information the user is supposed to read and understand.

So Warning SHOULD support localized text outside English, or it will
have an even harder time to get accepted than it already has..

What I remember from the prior discussion was to remove iso-8859-1 and
2047 from the general header definition to open up for new headers to be
specified using UTF-8 if they like, not that we should drop 2047 support
in existing headers defined as having human oriented text (Warning,
Auth*, maybe more). But it was long ago...

However I think we maybe want to revisit the general header syntax
description, making sure we do provide the intended guidance for those
who want to write extension headers requiring natural language content..
current wording kind of suggest such headers is not allowed.

Regards
Henrik

---

From: Julian Reschke <[email-masked]>
Date: Thu, 23 Jul 2009 22:14:41 +0200

Henrik Nordstrom wrote:
> ...

So do we have evidence that (a) RFC2047-encoded Warn headers are in use, 
and (b) that UAs do support them?

BR, Julian

---

From: Henrik Nordstrom <[email-masked]>
Date: Thu, 23 Jul 2009 22:51:26 +0200

> and (b) that UAs do support them?

No on both. We rather have evidence that most UAs blindly ignores
Warning not yet having implemented this part of the specs, and that the
ones who tries to display the warning do not support RFC2047.
Additinally most servers don't even issue Warning headers either even
when they should.

Brain cells firing again after reading over the Warning text a couple of
times more. And change of opinion. I am fine with reducing Warning
warn-text to the same level as Reason Phrase. English US-ASCII intended
mainly for debugging/tracing with the actual error description being the
code and not the text. Additionally this enables UAs to show the
warnings in various ways as they see fit, not restricted to textual
display.

This works fine for all the defined errors except the "misc" errors (199
& 299).

Regards
Henrik

---

From: Mark Nottingham <[email-masked]>
Date: Fri, 24 Jul 2009 16:02:12 +1000

Tracking in <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/187>

On 23/07/2009, at 8:22 PM, Julian Reschke wrote:

> "The warn-text SHOULD be in a natural language and character set  
> that is most likely to be intelligible to the human user receiving  
> the response. This decision can be based on any available knowledge,  
> such as the location of the cache or user, the Accept-Language field  
> in a request, the Content-Language field in a response, etc. The  
> default language is English and the default character set is  
> ISO-8859-1 ([ISO-8859-1]).
>
> If a character set other than ISO-8859-1 is used, it MUST be encoded  
> in the warn-text using the method described in [RFC2047]." -- <http://greenbytes.de/tech/webdav/draft-ietf-httpbis-p6-cache-latest.html#rfc.section.3.6.p.9 
> >
>
> I think this should be dropped the same way we already did it for  
> the Reason Phrase (see <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/94 
> >).
>
> Best regards, Julian
>
>
>

--
Mark Nottingham     http://www.mnot.net/