- From: Dave Kristol <dmk@allegra.att.com>
- Date: Fri, 25 Aug 95 10:02:32 EDT
- To: sjk@amazon.com
- Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Shel Kaphan <sjk@amazon.com> wrote: > I mentioned this before, obliquely in a response on another topic, but > if I'm right, what follows can significantly reduce the potential > performance problems with DMK's State-Info proposal. > Key conclusion: An > idempotent request such as GET, which produces no side effects, cannot > affect the state of a stateful dialog. Therefore, it seems > unnecessary for requests that can be satisfied out of a cache to pass > through any information to the next server. > > This, of course, makes it even more imperative that caches not serve > cached documents they shouldn't. > > With the recent addition to the proposal that clients stay in the > "have state-info" state when there is no state-info in the server's > (or cache's) response, this means that caches need not "reflect" > state-info either. This idea sounds promising. Let me expand a bit from an operational standpoint. Remember the recent change whereby a user agent retains its State-Info if it receives no State-Info from a server. If caching proxies followed the rule that they cached only those documents for which they received no State-Info from the origin server, and if origin servers were careful to send State-Info only when it changed, I believe caching proxies would be able to cache anything cachable (in the State-Info context). Upon getting a one, a caching proxy could satisfy a request for a resource from the cache if there were a fresh one available, whether or not the request contained a State-Info request header. (That's a change, and it would indeed enhance caching.) The idea of an idempotent method could be expanded to imply that, not only does the resource not change, but its State-Info does not change either. (I guess that's obvious if you bundle State-Info into a larger concept of "the resource".) Nice idea! If the dust settles without major objections, I'll add this to a state-info-01 I-D. That will be a couple of weeks, after some vacation. Dave Kristol
Received on Friday, 25 August 1995 07:09:39 UTC