RE: Cache-Control and Pragma

Mark Nottingham wrote:

> I can't find anything in the Draft that addresses the situation when
> both Cache-Control and Pragma: no-cache headers are set, and they are in
> conflict. 
> For instance, if I use
> 
> Cache-Control: must-revalidate
> Pragma: no-cache
> 
> on a HTTP response, it would be desireable to have it cached (and always
> revalidated) by HTTP 1.1 caches, and not cached by HTTP 1.0 caches.
> However, I can see nothing in the Draft about this, and some
> implementations, upon reading 14.32 Pragma, might never cache the
> object. While the action is safe, it's not ideal.
>  
> Am I missing something somewhere? Thanks.

The interaction of headers whose interaction is not specified
is not specified.

An origin server cannot depend on the precedence of
"Cache-Control: must-revalidate" and "Pragma: no-cache",
and a server (1.0 or 1.1) might ignore either or both.

Larry
-- 
http://www.parc.xerox.com/masinter