I'm sold, relying on Cache-Control: private is the better option. This behavior does affect IFRAME rendering paths as well, though doesn't necessarily need to. Container-side rpc can be optimized without gadget-side rpc, since gadgets.rpc(function getRelayChannel()) will return the same value on each side.
As Brian mentions, every code path in GadgetRenderingServlet sets Cache-Control: private[,*] (except nocache=1, not an issue), so the potential effects are limited to JsServlet. So 1. Admittedly, any given deployment will likely see higher JsServlet traffic if choosing to opt into this feature; 2. this suggests that JsLibrary field isBrowserSpecific should be added, with JsServlet signaling noProxy behavior in caching headers when this bit is true for any library it emits. John On Tue, Jun 9, 2009 at 1:53 PM, Brian Eaton <[email protected]> wrote: > I don't trust the vary header any farther than I can spit. > > For example, at least one version of IE interprets a Vary header with > any value other than user-agent to mean "OMG, I don't understand, > don't cache this": > http://marc.info/?l=apache-modgzip&m=103958533520502&w=2 > > In a comment to Mark's blog post, he mentions other implementation issues: > > "More complex situations -- e.g., with multiple Vary headers and > multiple request headers -- caused problems on a number of > implementations (i.e., they'd return the wrong thing)." > > IMHO, we should stick to "cache-control: private." > > We need that on most iframes anyway, so this keeps the cache-control > changes from rippling out quite so far. > > On Tue, Jun 9, 2009 at 1:44 PM, John Panzer<[email protected]> wrote: > > This seems relevant: http://www.mnot.net/blog/2007/06/20/proxy_caching > > (It appears that Vary: is fairly safe in the sense that caches that don't > > deal with it nicely -- e.g., caching variants -- will just mark the > content > > as uncacheable. Though I don't think this was rigorously tested.) > > > > -- > > John Panzer / Blogger > > [email protected] / abstractioneer.org <http://www.abstractioneer.org/> > / > > @jpanzer > > > > > > > > On Tue, Jun 9, 2009 at 1:25 PM, <[email protected]> wrote: > > > >> Hi Paul: > >> > >> You're absolutely right. Vary: User-Agent; is preferable to me. Do you > >> have any reason in mind for why Cache-Control: private in addition to or > >> instead of Vary would be preferable? Ie. common support by various CDNs. > >> > >> I've been thinking how best to link service of custom rpc to setting > >> this header. Ultimately JsServlet or a Filter needs to do so. Thoughts > >> on this? The best idea I had was to add something like > >> isBrowserSpecific() to JsLibrary so that the relevant output code > >> (gadget rendering, js servlet) could act accordingly. > >> > >> Kevin - re: StringBuffer, comment isn't particularly prescriptive so > >> I'll assume the complaint is use of StringBuffer rather than > >> StringBuilder. If so, fixed. If not, let me know. > >> > >> > >> http://codereview.appspot.com/63210 > >> > > >
