Re: Preemptive and reactive content negotiation

On Wed, 6 Sep 1995, Koen Holtman wrote:
> Roy Fielding:
> >There are two ways to do content negotiation: preemptive or reactive.
> >I think preemptive content negotiation is doomed to failure in the
> >long term, which is why I added the 300 response code.  When the
> >day comes that preemptive content negotiation (Accept* headers) are
> >more costly than reactive (an extra round-trip carrying a URC),
> >then browsers and server can switch without changing the protocol.
> 
> I think preemptive content negotiation on *all* types a browser
> supports is too costly already.

Correct - but you don't need to do it for all, just the ones you would 
prefer to see.  If a browser *can* do HTML 3.0, it says "I can do HTML 
3.0", the server might come back and say "sorry (406), I only have HTML 
2.0 and a PDF version of this file", so the browser goes "okay, I'll take 
the HTML 2.0".  The browser should decide where that tradeoff point is 
for itself - the tradeoff between being conservative in what types you 
declare you can accept, and the overhead of getting a 406.

Not everything has to go in the Accept header, just what you'd really 
like to see.

	Brian

--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--
brian@organic.com  brian@hyperreal.com  http://www.[hyperreal,organic].com/

Received on Wednesday, 6 September 1995 15:00:56 UTC