How does JobScheduler handle daylight saving time and time zones?
Configuration
The JobScheduler uses the time zone of its host, unless specifically configured to do otherwise.
The time zone of the JobScheduler can be configured http://www.sos-berlin.com/doc/de/scheduler.doc/command_line.xml#option_time-zone -time-zone command line option or the time_zone attribute, if the JobScheduler is to be operated in or with another time zone as its host.
Job and order time zones can be set using either the time_zone attribute or run_time.
Time zones are specified in JobScheduler according to the TZ database.
Daylight saving time
UTC does not change with the seasons, but local time or civil time may change if a time zone jurisdiction observes daylight saving time (summer time).
Modification of start times or stopping the JobScheduler during the change over or shift between standard and daylight saving times is not necessary. Der JobScheduler uses UTC times for all its internal operations. This ensures a continual flow of operation without breaks or repetitions regardless of any changes in local time.
Change from standard time to summer time
The clock is moved forward during the change from standard to summer (daylight saving) time (in Germany this takes place between 2 and 3 o'clock in the morning, standard time) and start times that are scheduled in this period are 'postponed' until the start of summer time (3 o'clock in the morning in Germany, standard/summer time). This ensures that all runs planned for the 'missing' hour are carried out. Repeat intervals, that are scheduled for the missing hour are generally only carried out once.
Change von summer time to standard time
No particulart measures are required during the change from summer to standard time. Even when 'putting back the clock' causes the hour to be 'repeated' (when seen from the standpoint of local time), JobScheduler's internal use of UTC ensures a continual flow of operations (see the examples later in this FAQ). In turn, this ensures that unwanted repetition of planned jobs and orders is avoided.
Agent operation
The time zone of the JobSchedulers, under which a job has been configured determines the point in time when a job or order is executed. This means that the time zone of the client and not that of the agent applies when a job or order is being executed remotely.
The Agent can be seen simply as a program that takes over the processing and does not have any influence over the control (i.e. the runtimes) of the processes themselves. Control lies exclusively with the client.
If, however, an Agent is started with the "JobScheduler" role then the local time zone of the Agent/JobScheduler will apply for locally configured jobs and orders.
Examples
The folowing examples illustrate the changes between standard and summer time for the city of Helsinki in the year 2012.
They also make clear that the UTC time, which JobScheduler uses internally, progresses uniformly even during the change from standard to daylight saving time.
Standard time in Helsinki is UTC +2h, daylight saving time is UTC +3h.
Change from standard time to summer time
In contrast to Germany, the change over from from standard to summer time 3 Uhr statt.
lokale Zeit Helsinki UTC-Zeit Zeitversatz in h Bemerkung ---------------------- ---------------------- ---------------------- ---------------------- 2012-03-25 02:30 2012-03-25 00:30 2 Noch Standardzeit 2012-03-25 03:00 2012-03-25 01:00 2 Beginn der Sommerzeit, Sprung von 3 auf 4 Uhr 2012-03-25 03:30 2012-03-25 01:00 2,5 Diese lokale Zeit gibt es nicht, die Stunde fehlt, Startzeiten werden ggf. auf 4 Uhr verschoben 2012-03-25 04:00 2012-03-25 01:00 3 2012-03-25 04:30 2012-03-25 01:30 3
Change von summer time to standard time
Der Wechsel von Sommer- auf Standardzeit findet im Gegensatz zu Deutschland um 4 Uhr statt.
lokale Zeit Helsinki UTC-Zeit Zeitversatz in h Bemerkung ---------------------- ---------------------- ---------------------- ---------------------- 2012-10-28 02:30 2012-10-27 23:30 3 Noch Sommerzeit 2012-10-28 03:00 2012-10-28 00:00 3 3 bis 4 Uhr lokaler Sommerzeit 2012-10-28 03:30 2012-10-28 00:30 3 2012-10-28 04:00 2012-10-28 01:00 3 Ende der Sommerzeit, Sprung von 4 auf 3 Uhr 2012-10-28 03:30 2012-10-28 01:30 2 3 bis 4 Uhr lokaler Standardzeit 2012-10-28 04:00 2012-10-28 02:00 2 Standardzeit 2012-10-28 04:30 2012-10-28 02:30 2
Logging
The timestamp column in log files is displayed in the JobScheduler's time zone.
scheduler.log uses local time as before.
XML commands
Timestamps in XML answer are marked with suffix "Z" for UTC time.
Änderung von Zeitzonen
JobScheduler verwendet für Zeitoperationen die API Joda. In dieser ist die TZ Database integriert. Sollten sich aufgrund politischer Entscheidungen einzelne Zeitzonen ändern, so kann nach dem hier beschriebenen Verfahren die TZ-Database aktualisert werden.
Von einem Austausch der ausgelieferten Version der Joda API im lib Verzeichnis durch eine neuere Version raten wir dringend ab, da es evtl. Inkompatibilitäten zu früheren Versionen gibt, die
zu Fehlfunktionen des JobSchedulers führen können.