@Jayr and @Ikai, thanks for the assistance! Actually, I cannot change this requirement because this is the core of the business. I don't really need synchronized clocks between application instances, but I need a unique global vision of a regressive timer, which can be reset at any time. That is, I need one or more timers that can be reset according to client's actions on the UI, and clients need to know every second what is the value of the timer and what happened in the previous second.
I believe this is achievable on GAE since I found at least one product deployed on GAE which promises to implement the same kind of business... On Tue, Jun 28, 2011 at 1:14 AM, Ikai Lan (Google) <ika...@google.com>wrote: > Precision of seconds can be tough, BTW, because syncing clocks is a tough > problem that nobody has really solved. The mere act of making an RPC to a > backend or Memcache can introduce skew simply because the latency is not > predictable. Most of the time (99.999%) there shouldn't be an issue because > latency will be in milliseconds, but anything can happen in a distributed > environment. > > Depending on what it is you are doing, it may be simpler to change your > product requirements. > > A little related: http://en.wikipedia.org/wiki/Lamport_timestamps > Not that related but interesting: > http://en.wikipedia.org/wiki/Uncertainty_principle > > Ikai Lan > Developer Programs Engineer, Google App Engine > Blog: http://googleappengine.blogspot.com > Twitter: http://twitter.com/app_engine > Reddit: http://www.reddit.com/r/appengine > > > > On Tue, Jun 28, 2011 at 12:01 AM, jMotta <jayrmo...@gmail.com> wrote: > >> Loreno, >> >> I don't know what you mean with "global count down timer", if you want to >> trigger an action upon the end of the global count down you can use the * >> cron* implementation. >> >> Can you explain what is the use that you want with this? In "low-level >> speaking", the only ways to share state across multiple instances / requests >> safety from concurrent access issues and given the cloud nature of it is use >> the datastore and memcache. >> >> *Jayr Motta* >> Software Developer >> * >> * >> I'm on >> BlackBeltFactory.com<http://www.blackbeltfactory.com/ui#%21User/jmotta/ref=jmotta> >> ! >> >> >> >> On Mon, Jun 27, 2011 at 12:48 PM, lorenoolive...@gmail.com < >> lorenoolive...@gmail.com> wrote: >> >>> Is it possible to implement a global count down timer in GAE/J? I would >>> like an unique timer to be shared among all the application instances. The >>> precision of the timer is seconds. >>> >>> Any idea? >>> >>> -- >>> 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-java@googlegroups.com. >>> To unsubscribe from this group, send email to >>> google-appengine-java+unsubscr...@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. >> To post to this group, send email to >> google-appengine-java@googlegroups.com. >> To unsubscribe from this group, send email to >> google-appengine-java+unsubscr...@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. > To post to this group, send email to > google-appengine-java@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@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. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
