synchronize a "mocked" clock in a distributed system
in [Ruby]
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From: Chuck Remes on 6 Jul 2010 14:47 On Jul 6, 2010, at 12:52 PM, Tony Arcieri wrote: > On Mon, Jul 5, 2010 at 3:15 PM, Chuck Remes <cremes.devlist(a)mac.com> wrote: > >> Because there is no centralized server that all messages, data or control >> must pass through. >> > > If your system is fully asynchronous and there's no central data source, how > is it possible for nodes to synchronize to a central clock? That makes > absolutely no sense. I wrote a long email describing why I thought I was right, but I kept coming back to your earlier question about a centralized data source. The problem I have with my data source is that the documents within it have different time granularities for the data. For example, some documents represent data aggregated over 1m, 1 day or 1 week. Since documents of each time granularity may be requested by various processes, I didn't see how I could use them as a source for the mock clock. And then it hit me. I could have a mock clock process that subscribes to all of those data sources and receives all of those messages. The mock clock should *only* pay attention to the document data with the smallest time granularity for setting the clock and ignore the rest. So yes, you are right. I *do* have a central data source that I can use to set the clock. I just didn't see it before. Thanks for pressing me on this. It forced me to really figure it out. cr
From: Tony Arcieri on 6 Jul 2010 20:10
[Note: parts of this message were removed to make it a legal post.] Cool, glad I could help On Tue, Jul 6, 2010 at 12:47 PM, Chuck Remes <cremes.devlist(a)mac.com> wrote: > On Jul 6, 2010, at 12:52 PM, Tony Arcieri wrote: > > > On Mon, Jul 5, 2010 at 3:15 PM, Chuck Remes <cremes.devlist(a)mac.com> > wrote: > > > >> Because there is no centralized server that all messages, data or > control > >> must pass through. > >> > > > > If your system is fully asynchronous and there's no central data source, > how > > is it possible for nodes to synchronize to a central clock? That makes > > absolutely no sense. > > I wrote a long email describing why I thought I was right, but I kept > coming back to your earlier question about a centralized data source. The > problem I have with my data source is that the documents within it have > different time granularities for the data. For example, some documents > represent data aggregated over 1m, 1 day or 1 week. Since documents of each > time granularity may be requested by various processes, I didn't see how I > could use them as a source for the mock clock. > > And then it hit me. I could have a mock clock process that subscribes to > all of those data sources and receives all of those messages. The mock clock > should *only* pay attention to the document data with the smallest time > granularity for setting the clock and ignore the rest. > > So yes, you are right. I *do* have a central data source that I can use to > set the clock. I just didn't see it before. > > Thanks for pressing me on this. It forced me to really figure it out. > > cr > > > -- Tony Arcieri Medioh! A Kudelski Brand |