Re: Major errors in Caching and Cache-Control
Benjamin Franz (snowhare@netimages.com)
Wed, 5 Jun 1996 13:33:20 -0700 (PDT)
On Wed, 5 Jun 1996 jg@w3.org wrote:
> There are two issues here:
>
> 1) what content authors can/need to say about how their content
> might be modified.
>
> 2) what HTTP allows/disallows in the protocol.
>
> To begin with, believing that all web stuff uses HTTP is a mistake;
> in particular, we'd like to eventually transition to other transport
> protocols, which may potentially take a more liberal view of content.
> It seems perfectly reasonable to me, particularly working for an international
> company as I do, to think that a set of proxies that
> transformed all GIF files to JPEG before transporting them across the
> expensive interoceanic links would BE A GOOD THING. This may very well
> save me 2X on bandwidth right now. Not a trivial deal at all. I'd
> like my cache to be more efficient as well, and would like to store the
> data that way.
As a site developer I can tell you that silent content transformation is
*EVIL*. AOL was converting JPEGs to ART silently this way. Caused one of
my clients some grief as people on AOL downloaded files with a .jpg ending
and their viewers puked on it. Fortunately I was aware of the possibility
that AOL might be doing this and could guide the user in *disabling* the
JPEG->ART transformation. I am NOT in favor of content transformation
by proxies in the least. The legal ramifications alone are potentially
killers.
> It seems to me that the sooner we get "no-transform" into the hands of
> content authors the ability to say that this data better not be messed
> with between me and the end user, the better. I'd sure not want my
> medical images so messed with. People will (already are) experimenting
> with such data transformation in research contexts; wouldn't surprise me
> (might even take bets on) people doing it for product.
See above.
> I think that "no-transform" is worth having, even if HTTP forbids transformation
> (for which I think forbidding tranformations would be draconian, and people
> who run corporate or island cache systems would not thank you for).
I think that transformations *should* be forbidden. You want to break
protocal inside an organization fine - but don't tempt fate by allowing it
on the big bad net.
> Note that adding it later is closing the barn door after the animals escape;
> we'd like content authors to start now, so that such proxy systems might
> be deployed in the future, while allowing critical data to be marked.
If this allowed at all, it should be in the affirmative mode:
transform-allowed. The default without question should be no content
transformations allowed unless explicitly stated otherwise. At no point
should intermediates be allowed to transform content unless I
affirmatively give them permission to do so.
--
Benjamin Franz