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Re: More clarifications on object processing

From: Francois Daoust <fd@w3.org>
Date: Thu, 12 Jun 2008 17:37:26 +0200
Message-ID: <485142B6.6030904@w3.org>
To: Dominique Hazael-Massieux <dom@w3.org>
CC: public-bpwg-comments <public-bpwg-comments@w3.org>

Hi Dom,

See inline for some comments on your comments, with a view to 
identifying precisely the bits that may need clarification.


Dominique Hazael-Massieux wrote:
> While implementing the new last call version of mobileOK, I found a few
> places where the processing of the objects could be clarified:

> * when analyzing external resources (in ContentFormatSupport,
> PageSizeLimit, ExternalResources), the objects and images that are set
> as fallback of an object that is in an acceptable format shouldn't be
> counted. For instance,
> <object data="myimage.gif"><img src="myimage.png" alt=""/></object>
> shouldn't trigger an error in ContentFormatSupport, the weight of
> myimage.png shouldn't be counted in PageSizeLimit and ExternalResources

Part to clarify:
  "object means "object" and "img" in the note on objects to include in 
2.4.6 Included Resources"

The additional note introduced in the latest version in 2.4.6 Included 

"Note: object elements that are accessed in order to test their 
Content-Type HTTP header, but do not form part of the ultimate 
representation of the resource under test (see 3.15 OBJECTS_OR_SCRIPT ), 
are not considered to be included resources. Their treatment, as regards 
3.16 PAGE_SIZE_LIMIT and 3.6 EXTERNAL_RESOURCES , is described in the 
relevant section."

... was meant to address this particular problem.

In the following example: <object data="myimage.gif"><object 
data="myimage.png">Blah</object></object>, the behavior is correct 
right? "myimage.png" is not taken into account in ContentFormatSupport, 
PageSizeLimit and ExternalResources, as should be expected.

The point in your example is we're only talking about "object" elements 
in the note whereas in this case, the "object" element should be 
regarded as encompassing "img" elements as well, am I correct? This 
should be noted (as the note that appears right before the above quoted 
one suggests: "In some circumstances object elements may act as synonyms 
for other elements such as img and iframe. In these cases it is noted in 
the relevant section when to regard object elements as equivalents for 
other elements.").

> * similarly, I don't think we want to raise a ContentFormatSupport error
> on <object data="myimage.png"><img src="myimage.gif" alt="" /></object>
> since this is using correctly the fallback mechanism; while this gets
> accepted by ObjectsOrScript, this would currently raise an error in the
> way I read ContentFormatSupport; 

Part to clarify:
  "ultimate representation of the resource under test"

[Side note:
The Accept header precises that only image/gif and image/jpeg are supported.
Is it still correct to send a PNG image even with a fallback mechanism?
I think it is, I'm raising the point in case it's not...]

 From the note above, since "myimage.png" does "not form part of the 
ultimate representation of the resource under test", the test should not 
apply on "myimage.png".

> * I don't think "myimage.gif" should be counted as external
> resources/page size limit in the following instance:
> <object data="myimage.gif" type="image/png">Hello</object> - the current
> text says to "include those objects whose content type is either
> "image/jpeg" or "image/gif" irrespective of whether the type attribute
> is specified.", but it's not clear why.

Part to clarify:
  The note on how to select objects at the beginning of 

It may deserve clarification, but this restriction applies to the set of 
"objects retrieved under the 3.15.1 Object Element Processing Rule". An 
object with an "image/png" type won't be retrieved by the Object Element 
Processing Rule, so "myimage.gif" won't be counted.

> * if I hit an HTTP redirect, does the size of the page served as the
> redirect page counts in PAGE_SIZE_LIMIT-1 or only
> under ´╗┐PAGE_SIZE_LIMIT-2? I've implemented the latter since I find it
> less confusing, but the spec could be clearer about it

Part to clarify:

  In 2.4.3 HTTP_RESPONSE, precise the total to which the size of the 
response should be included (I propose the second as well)
  In 3.16 PAGE_SIZE_LIMIT, link back to 2.4.3 HTTP_RESPONSE to precise 
what we mean by "the size of the document" and "the size of the response 
body". This would be consistent with 3.6 EXTERNAL_RESOURCES that 
includes such a link.
Received on Thursday, 12 June 2008 15:37:59 UTC

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