Rob Raisch (
Tue, 13 Jul 1993 16:05:11 -0400 (EDT)

On Tue, 13 Jul 1993, Tim Berners-Lee wrote:

> Dave asks how one can specify particular pererences for
> retrieval of an object in the link. I don't think
> this is information for the link. In HTTP it is transferred
> atthe time of retrieval from the server, the HTTP headers
> containing information for stating prefernces for variants
> (language, representation, encoding).
> I thinkwork is needed on parameters to hte representations
> like
> image/gif
> is all very well, but
> image/gif height=200 width=400 colours=8
> provides better information for the server, allowing it to
> select or generate an image more accurately, and save bandwidth.

Tim, this really begs the following question:

If I am a browser which only displays monochrome GIFs, and the
item is only available as a 24bit colour JPEG, whose responsibility
is it to do the conversion?

I'd expect that instead of having the server tell the client that
it can serve it only as: image/jpeg colours=24
and leave the retrieval decision to the browser, (which most times
is less powerful and feature-ful than the server),
would it not be a better decision to have the browser tell the server
what capabilities it had, and let the server make the proper
conversions to serve it in an appropriate form?

The server is more capable of doing the conversion and making
intellegent decisions regarding what is required to meet the needs
of the browser.

The other way round the server must tell the client what *possible*
forms the property can be served in, and this quickly becomes
unmanageable. (Consider that GIFs are available with the following
attributes: width, heigth, colour(bits), dots-per-inch, aspect)