On 31/01/2012, at 4:45 AM, Caitlin Bestler wrote: > Mark Nottingham asked: > >> Why not just use >> Cache-Control: no-cache? > >> That way, intervening caches will do the right thing too... > > > Even with no caching anywhere you still have N replicas (typically three) > that will be updated in an arbitrary order, > and clients that read from any one of those replicas.
Right.. all that I'm saying is that the semantics of CC: no-cache are effectively the same as X-Newest, and have the nice side effect of busting any intermediary caches along the way. > Unless you implement a draconian global locking scheme there is nothing you > can do to prevent a client from reading > a copy that has just been rendered obsolete by another client completing the > edit of the (N+1)/2th replica. ?? > If the goal is to validate with all N servers then this should be a special > transaction. The benefits of caching should remain > In place for typical reads. and they will, if you don't use CC: no-cache on them. Regards, -- Mark Nottingham http://www.mnot.net/ _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : openstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
