W3C home > Mailing lists > Public > public-xhtml2@w3.org > March 2010

Re: My point about the negotiation algorithm

From: Steven Pemberton <Steven.Pemberton@cwi.nl>
Date: Wed, 31 Mar 2010 16:15:10 +0200
To: "Shane McCarron" <shane@aptest.com>, "Steven Pemberton" <Steven.Pemberton@cwi.nl>
Cc: "XHTML WG" <public-xhtml2@w3.org>
Message-ID: <op.vafq7kmpsmjzpq@acer3010>
On Wed, 31 Mar 2010 15:23:10 +0200, Shane McCarron <shane@aptest.com>  

> So, your position is that the document should instruct people to ignore  
> 'the relative importance ("weight")' that is specified via the q value  
> because even if the user agent thinks text/html would be better, the  
> document should STILL be sent as application/xhtml+xml?  That surprises  
> me.  Granted this document is not a tutorial on all the intricacies of  
> content negotiation, but I feel it is a mistake to tell a document  
> author to ignore the mandate of another standard.  Am I missing  
> something here?

Well, it may have many other formats with an even higher q value. If its  
favourite media type was for pdf, I don't think we should recommend  
converting to pdf. The point of this document is to say how to serve  
XHTML. If the browser accepts it, you should look no further.


> Steven Pemberton wrote:
>> On Wed, 31 Mar 2010 15:04:27 +0200, Shane McCarron <shane@aptest.com>  
>> wrote:
>>> What if the q value for application/xhtml+xml is 0?
>> Is is the same as saying it doesn't accept it:
>> 3.9 Quality Values
>>    HTTP content negotiation (section 12) uses short "floating point"
>>    numbers to indicate the relative importance ("weight") of various
>>    negotiable parameters.  A weight is normalized to a real number in
>>    the range 0 through 1, where 0 is the minimum and 1 the maximum
>>    value. If a parameter has a quality value of 0, then content with
>>    this parameter is `not acceptable' for the client.
>> http://tools.ietf.org/html/rfc2616#section-3.9
>> Steven
>>> Steven Pemberton wrote:
>>>> The point of the XHTML Media Types note  
>>>> (http://www.w3.org/MarkUp/2010/ED-xhtml-media-types-20100218/) is to  
>>>> explain how to deliver XHTML to a browser.
>>>> If the browser says it accepts application/xhtml+xml, our job is  
>>>> done: use that media type; you don't have to follow any extra  
>>>> guidelines.
>>>> However, if it is a legacy browser, and doesn't accept  
>>>> application/xhtml+xml, then there is a fallback: deliver it as  
>>>> text/html (but make sure it won't hiccup on your content by following  
>>>> a number of guidelines).
>>>> So even if a browser says it accepts both media types, even if it  
>>>> says it 'prefers' text/html (via a q value), our aim is to deliver  
>>>> XHTML, and so should use the application/xhtml+xml media type.
>>>> Steven
Received on Wednesday, 31 March 2010 14:15:56 UTC

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