On 03/07/2019 13:14, Salz, Rich wrote: >> I don't think so. IINM, HTTP caching only comes into play when a client > sends a subsequent HTTP request message that may (or may not) be > satisfied by a cached HTTP response message. > > A client that follows caching shouldn't send a new request if the > cache-control headers on the first response direct it not to, right?
Right, but the prerequisite is that the client explicitly wants to obtain a fresh (or at least unexpired) HTTP response message. If that's not the case, then HTTP caching doesn't come into play, because HTTP itself doesn't come into play. ISTM that once an ACME client has extracted a directory object from an HTTP response message, then both HTTP and HTTP caching are no longer in play. The client is now only dealing with a directory object, not an HTTP response message. (From Jacob's message, I get the impression that this is the prevailing understanding). > > Clients could also use If-Modified-Since, right? > > Good point. > > Then maybe the errata could just be > Clients SHOULD use an If-Modified-Since header to get more effective > caching. I think that's a useful optimization suggestion, but I don't think it addresses the issue. The idea behind the erratum is to force HTTP caching rules to apply to directory objects, so that servers can update their directory objects and expect clients to take note. -- Rob Stradling Senior Research & Development Scientist Sectigo Limited _______________________________________________ Acme mailing list [email protected] https://www.ietf.org/mailman/listinfo/acme
