- From: Yves Lafon <ylafon@w3.org>
- Date: Fri, 1 Jul 2011 12:13:01 -0400 (EDT)
- To: David Booth <david@dbooth.org>
- cc: Ian Davis <lists@iandavis.com>, Tim Berners-Lee <timbl@w3.org>, "www-tag@w3.org List" <www-tag@w3.org>
On Fri, 1 Jul 2011, David Booth wrote:
>>> would help us avoid the IR/non-IR rat hole in that discussion. What do
>>> you think?
>>>
>>
>> There are quite a few situations where the representations of a
>> resource do not share its properties. For example, the generator of a
>> resource might be OpenOffice, but the generator of its representation
>> could be Apache. And of course intermediaries could be modifying the
>> representations along the way without permission by publisher or
>> consumer. For example, many mobile ISPs transcode images to save
>> bandwidth and even inject javascript into pages to provide tooltips on
>> those images saying "click image to improve quality". This risks
>> confusion when the representations include license information as the
>> end user could easily assume wrongly that the license covers the
>> injected script.
>
> True. When we say that the license applies to "all http
> representations" that should be understood to mean "all *authorized*
> http representations", since the publisher cannot be held responsible
> for changes made to the representation by intermediaries during
> transport.
See http://tools.ietf.org/html/rfc2616#section-14.46
It defines extra information sent via a "Warning" header
<<
214 Transformation applied
MUST be added by an intermediate cache or proxy if it applies any
transformation changing the content-coding (as specified in the
Content-Encoding header) or media-type (as specified in the
Content-Type header) of the response, or the entity-body of the
response, unless this Warning code already appears in the response.
>>
So, in theory, the receiver should know when the representation has been
modified in transit.
--
Baroula que barouleras, au tiéu toujou t'entourneras.
~~Yves
Received on Friday, 1 July 2011 16:13:03 UTC