W3C home > Mailing lists > Public > ietf-http-wg-old@w3.org > May to August 1995

Re: Possible New Optional Field in Heade

From: Brian Behlendorf <brian@organic.com>
Date: Wed, 10 May 1995 13:57:11 -0700 (PDT)
To: Larry Masinter <masinter@parc.xerox.com>
Cc: DLEVINE@ssf4.jsc.nasa.gov, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Message-Id: <Pine.3.89.9505101302.H24326-0100000@eat.organic.com>
On Wed, 10 May 1995, Larry Masinter wrote:
> As for a client-supplied link-speed estimate, I'll just point out that
> this is something that the server may be in a better position to
> estimate than the client. 

True, but hopefully the web site designer is already compensating for that
(by not using big images when they're on the slow end of a 14.4, etc).  The
server load and bandwidth are known entities - the client bandwidth isn't
known, and is what we're looking for ways to express.

The "mxb" and "mxs" parameters are close, but not quite the cleanest way 
to express *in*a*relative*way* whether I want high-bandwidth information 
or low bandwidth information.  Consider the following two versions of an 
object the server can provide:

1) High bandwidth: a 20K HTML page (lots of formatting and style sheet info)
	with 2 50K inlined logo images and 10 5K inlined icons.

2) Low bandwidth: a 10K HTML page with 2 15K logos and no icons.

Presume that the inlined images of one page wouldn't make sense in the 
other - the 15K logos *aren't* a direct replacement for the 50K logos.

How do I express, in a general sense, that I'd rather see #2?  I don't want
to set my text/html mxb to be 15K, because there are lots of >15K documents
I'd probably be happy to wait to download.  And I can't vary it on image/gif,
because the html page has already loaded; and even if the images were
interchangeable, a provider could easily just break up their large 50K image
into 5 10K images and I'd still be left with a heavily loaded page. 

Conceivably, my browser could have a concept of how much data per page I'm
willing to accept, i.e. "I want 50K or less per page" - after downloading and
measuring the 10K HTML page, it sets the mxb to be 8K for each of 5 inlined
images.  But even that is clumsy. 

I guess the main problem is that people will be thinking of "how long I'll
wait for this page to render" in terms of seconds (which over a slow pretty
much directly maps to bytes), and not in "how long I'll wait for each part of
this page".  And even then there are other factors - how the page is laid
out, formatting hints, etc.  Expressing that in an absolute limit on page
elements doesn't seem to be the right way for the server to know,
big-picture, what the client wants. 

	Brian

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brian@organic.com  brian@hyperreal.com  http://www.[hyperreal,organic].com/
Received on Wednesday, 10 May 1995 13:58:07 EDT

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