Multipart/mixed for many inline images (was Re: Toward Closure on HTML)

Chris Lilley, Computer Graphics Unit (
Fri, 8 Apr 1994 13:07:44 GMT said:

>[I said:]

>> The browser can tell the difference by parsing the link.

>Did you get a reply to this?

Not really. The current stuff about the DTD seems to have somewhat swamped my

>The browsers can't tell what type a URL is by parsing the link.

Could you elaborate? It seems to me that they can. If a link is of the form

http://site/path/blah.html its an html file
http://site/path/blah.tif its an image, etc.

Sure if someone defined *.gif to be text/html in their servers list of mime
types that might be a problem, but that would be perverse in the extreme. How
many html pages are there on the web, and what percentage of them do not have a
file type of .html or .htm (for broken DOS systems ;-0 )

All a browser would have to do is detect that the link it is about to follow is
to an html file, switch on or off image types in the accept field as
appropriate, then add multipart/mixed in the accept field.

Marc suggested that my suggestion wasted already cached images, which is true;
but then if they are all retrieved in a block the inefficiency is not that

An alternative would be to have the browser construct a list of images in the
current document that are not in the browsers cache; however extending the
syntax of a GET to allow lists seems a bigger task. Could be the way to go,

Apart from that, and Marc's comment, the topic seems to have sunk without trace.
A pity; it seemed such a simple, largely impact free optimisation, primarily
using existing technology.

Chris Lilley
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