Hi Dave,
I wrote on 1/23/03:
>> >I propose that the following paragraph be added to the Section B.2 of
> >the XHTML-Print spec:
>> >Producers and consumers of Application/Vnd.pwg-multiplexed entities, as
> >defined in [MIMEMPX], should consider each image as having one and only
> >one reference. The producer should not make assumptions about the
> >buffering abilities of the consumer of an
> >Application/Vnd.pwg-multiplexed entity and include a copy of an image
> >for each reference to it. Consumers may release the resources
> >associated with an image when the reference to it is satisfied, and are
> >free to optimize references to identical images in an implementation
> >dependent manner.
>You wrote on 1/27/03:
> I'd be hesitant to just recommend that a producer provide
> multiple copies of each image without specifying additional
> detail. RFC2557 (referenced by RFC3391) tells us how to
> resolve references in a compound document mandates that each
> part of the multipart message have a unique ContentID and/or
> unique Content-Location.
Dave,
What if the contentID were unique for each image but the content-Location
identical for each identical image. For example, in the case of a series of
paragraphs that start with the same image, an information icon, the document
would look like the following:
<p class="info"><img src="info_icon.jpg" height="10" width="10">
Informational message: daba daba do...
</p>
<p class="info"><img src="info_icon.jpg" height="10" width="10">
Windows Haiku:
Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.
</p>
Then the multiplexed document would interleave the same image twice, each
with different contentID's but identical, "info_icon.jpg",
content-Locations. For example the multiplexed document could look like the
following:
Content-Type: application/vnd.pwg-multiplexed;
type=application/vnd.pwg-xhtml-print+xml
CHK 1 428 LAST
Content-Type: application/vnd.pwg-xhtml-print+xml
Content-Location: infomsg.html
Content-Disposition: inline
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://ww.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>info</title>
</head>
<p class="info"><img src="info_icon.jpg" height="10" width="10">
Informational message: daba daba do...
</p>
CHK 2 1024 LAST
Content-ID: <49568.45876xxx at foo.com>
Content-Location: info_icon.jpg
Content-Type: image/jpeg
Content-Disposition: attachment
... Bytes of info_icon.jpg ...
CHK 3 253 LAST
Content-Type: application/vnd.pwg-xhtml-print+xml
Content-Location: infomsg.html
Content-Disposition: inline
<p class="info"><img src="info_icon.jpg" height="10" width="10">
Windows Haiku:
Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.
</p>
CHK 4 1024 LAST
Content-ID: <49568.46000xxx at foo.com>
Content-Location: info_icon.jpg
Content-Type: image/jpeg
Content-Disposition: attachment
... Bytes of info_icon.jpg ...
CHK 5 113 LAST
Content-Type: application/vnd.pwg-xhtml-print+xml
Content-Location: infomsg.html
Content-Disposition: inline
<body>
</body>
</html>
CHK 0 0 LAST
This method would allow the printer to only store the single image since the
names are the same.
Based on this approached I suggest the following, amended paragraph be added
to section B.2:
Producers and consumers of Application/Vnd.pwg-multiplexed
entities, as defined in [MIMEMPX], should consider each
image as having one and only one reference. The producer
should not make assumptions about the buffering abilities
of the consumer of an Application/Vnd.pwg-multiplexed
entity and include a copy of an image for each reference
to it. Each chunk containing an image should have a unique
ContentID and a Content-Location whose value is the name
of the image referenced in the src attribute of the img
element or the href attribute of the object element.
Consumers may release the resources associated with
an image when the reference to it is satisfied, and are
free to optimize references to identical images in an
implementation dependent manner.
Jim Bigelow,
Editor: XHTML-Print & CSS Print Profile
IEEE-ISTO, Printer Working Group
http://www.pwg.org/xhtml-print
Hewlett-Packard
208-396-2068
jim.bigelow at hp.com