I love the complete ecosystem you are step by step building. This is so great!
Stef On Feb 26, 2013, at 1:42 PM, Sven Van Caekenberghe <s...@stfx.eu> wrote: > Hi, > > It is often important, especially for server applications, to know if the > current local clock is still OK. The standard way for doing that is part of > NTP (http://en.wikipedia.org/wiki/Network_Time_Protocol). I implemented two > SNTP clients (one with ZTimestamp's second precision and another one using > DateAndTime's nanosecond precision) that can be used to check the difference > between the local clock and the clock of any NTP server. > > ZTimestampPreciseSNTPClient new clockDifference. > > -0:00:00:00.005786228 > > This reports that the difference between the local and remote clocks is in > the order of 5ms, as computed in one specific way. Other queries are related > to the Clock synchronisation algorithm. > > ZTimestampPreciseSNTPClient new localClockOffset. > > 0:00:00:00.065466869 > > ZTimestampPreciseSNTPClient new roundtripDelay. > > 0:00:00:00.037001908 > > In practice the following would be a useful practical check. > > ZTimestampPreciseSNTPClient new > enforceClockDifference: 2 seconds > ifFail: [ :delta | > self warn: ('Clock difference {1} > 2s' format: { delta > }) ]; > close. > > As NTP uses UDP datagrams, this is a nice example for that as well. The code > can be found in the following repository: > > http://mc.stfx.eu/Neo > > It is probably easiest to load the ZTimestamp configuration using the > Configuration Browser and then load the bleeding edge version (it is not in > de released version). The code is self-contained and loads cleanly. > > ConfigurationOfZTimestamp project bleedingEdge load. > > The client contacts a server from pool.ntp.org. The code does only deal with > a limited aspect of NTP, which is rather complex and wonderful subject matter > (http://tools.ietf.org/html/rfc2030). My goal was to get a dependable result, > not be be super accurate. > > Enjoy. > > Sven > > -- > Sven Van Caekenberghe > http://stfx.eu > Smalltalk is the Red Pill > >
