On Wed, Mar 3, 2010 at 1:52 PM, Ikai L (Google) <ika...@google.com> wrote:
> Browsers use the expires header in conjunction with a URL locally to > determine whether or not to request a resource. If this has expired or does > not exist, browsers will then do a conditional get. The web server will > return a 304 response if the resource has not been modified, so this will > add additional latency to overall page load performance. You can validate > these assertions using the Firebug and the web developer plugins for > Firefox. > > In general, the rule is to not use Etags: > http://developer.yahoo.com/performance/rules.html I'll follow up to see if > the same restrictions apply on App Engine. My gut feeling is "no", because > we probably have some consistent way of generating the Etags, but I can't > say with any certainty just yet. > > Yeah, none of this applies to App Engine. We currently implement etags for static files, and plan to give you some tools to generate and implement etags when serving dynamic blobs via the blobstore API. If you're serving other files, you'll have to handle the ETag and If-None-Match headers yourself, and I don't believe that we interfere with you doing this now. > There's a couple of caching rules here: > http://blog.tylerholmes.com/2008/05/http-headers-and-caching-cache-control.html > > > On Tue, Mar 2, 2010 at 8:08 AM, George Moschovitis < > george.moschovi...@gmail.com> wrote: > >> Yes, I am setting a cookie. >> >> The session leakage problem is interesting. I have a question though, >> does the Expires header have precedence over the LastModified/ETag >> headers? >> I would like to use the LastModified/ETag headers to implement >> conditional GET, are you sure that ETag has precedence over the >> Expires header? (I am using cache-control: private) >> >> btw, thanks for the answer. >> >> -g. >> >> On Mar 1, 8:39 pm, "Ikai L (Google)" <ika...@google.com> wrote: >> > Are you setting a cookie? We force an expires header for any requests >> that >> > have a set-cookie header. The reason for this is that many users access >> > websites using HTTP proxies. Some proxies will cache the entire request, >> > which may cause session leak (e.g. let you read someone else's email). >> > >> > On Mon, Mar 1, 2010 at 7:09 AM, George Moschovitis < >> > >> > >> > >> > >> > >> > george.moschovi...@gmail.com> wrote: >> > > I don NOT want to set an Expires header. I am just curious with the >> > > header is added (and messes up with my caching scheme) >> > >> > > -g. >> > >> > > > Well, if you do not like what GAE sets as Expires value, why not set >> > > > yours? >> > >> > > > On Mar 1, 11:18 am, George Moschovitis < >> george.moschovi...@gmail.com> >> > > > wrote: >> > >> > > > > > Could you provide some code please? >> > >> > > > > What kind of code should I provide? I do NOT set the Expires >> header in >> > > > > my code, and still GAE automatically adds the Expires header. >> > >> > > > > -g. >> > >> > > -- >> > > You received this message because you are subscribed to the Google >> Groups >> > > "Google App Engine for Java" group. >> > > To post to this group, send email to >> > > google-appengine-j...@googlegroups.com. >> > > To unsubscribe from this group, send email to >> > > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com><google-appengine-java%2B >> unsubscr...@googlegroups.com> >> > > . >> > > For more options, visit this group at >> > >http://groups.google.com/group/google-appengine-java?hl=en. >> > >> > -- >> > Ikai Lan >> > Developer Programs Engineer, Google App Enginehttp:// >> googleappengine.blogspot.com|http://twitter.com/app_engine >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Google App Engine for Java" group. >> To post to this group, send email to >> google-appengine-j...@googlegroups.com. >> To unsubscribe from this group, send email to >> google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com> >> . >> For more options, visit this group at >> http://groups.google.com/group/google-appengine-java?hl=en. >> >> > > > -- > Ikai Lan > Developer Programs Engineer, Google App Engine > http://googleappengine.blogspot.com | http://twitter.com/app_engine > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to > google-appengine-j...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. 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