Re: The problem with proxy-revalidate, and a proposed solution

Jeffrey Mogul:
>The other approach, which Paul favors (and I think I do, too) is
>define something like
>        Cache-control: proxy-maxage=NNN
>which supplies a separate age limit that applies only to shared
>caches.  For example, a server doing authentication or hit-metering
>might send:
>        Cache-control: max-age=30, proxy-maxage=0

I think you have a good case for adding a directive to get these
semantics.  However, I'm not very happy with proxy-maxage.  I prefer
to add an agent-max-age directive, which will (generally) _weaken_ the
age limit for user agents, like this:

        Cache-control: max-age=0, agent-max-age=30

I prefer agent-max-age because, unlike proxy-maxage, it is a `safe'
extension of the current set of directives.  With `safe', I mean that
a client which ignores the new directive, because it does not (yet)
know about it, would err on the safe side: this client would
revalidate earlier, not later.

We would have no choice but to go for a safe extension if process or
smooth deployment were issues, but it seems that they are not.  Still,
I prefer a safe extension, because it is better engineering practice.


Received on Friday, 3 January 1997 15:20:40 UTC