DCE_DTS, Application Routines
*Conan The Librarian (sorry for the slow response - running on an old VAX)
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/sys$common/syshlp/helplib.hlb DCE_DTS, Application Routines *Conan The Librarian (sorry for the slow response - running on an old VAX) |
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NAME
dts_intro - Introduction to DCE Distributed Time Service (DTS)
DESCRIPTION
The DCE Distributed Time Service programming routines can obtain time-
stamps that are based on Coordinated Universal Time (UTC), translate
between different timestamp formats, and perform calculations on time-
stamps. Applications can call the DTS routines from server or clerk
systems and use the timestamps that DTS supplies to determine event
sequencing, duration, and scheduling.
The DTS routines can perform the following basic functions:
+ Retrieve the current (UTC-based) time from DTS.
+ Convert binary timestamps expressed in the utc time structure
to or from tm structure components.
+ Convert the binary timestamps expressed in the utc time structure
to or from timespec structure components.
+ Convert the binary timestamps expressed in the utc time structure
to or from ASCII strings.
+ Compare two binary time values.
+ Calculate binary time values.
+ Obtain time zone information.
DTS can convert between several types of binary time structures that
are based on different calendars and time unit measurements. DTS uses
UTC-based time structures, and can convert other types of time
structures to its own presentation of UTC-based time.
Absolute time is an interval on a time scale; absolute time measurements
are derived from system clocks or external time-providers. For DTS,
absolute times reference the UTC standard and include the inaccuracy and
other information. When you display an absolute time, DTS converts the
time to ASCII text, as shown in the following display:
1992-11-21-13:30:25.785-04:00I000.082
Relative time is a discrete time interval that is often added to or sub-
tracted from an absolute time. A TDF associated with an absolute time is
one example of a relative time. Note that a relative time does not use
the calendar date fields, since these fields concern absolute time.
Coordinated Universal Time (UTC) is the international time standard that
DTS uses. The zero hour of UTC is based on the zero hour of Greenwich
Mean Time (GMT). The documentation consistently refers to the time zone
of the Greenwich Meridian as GMT. However, this time zone is also some-
times referred to as UTC.
The Time Differential Factor (TDF) is the difference between UTC and the
time in a particular time zone.
The user's environment determines the time zone rule (details are system
dependent).
If the user's environment does not specify a time zone rule, the system's
rule is used (details of the rule are system dependent). For example, on
OpenVMS systems, the rule pointed to by the filename in
SYS$SYSTEM:SYS$TIMEZONE_SRC.DAT applies.
The OSF DCE Application Development Guide provides additional information
about UTC and GMT, TDF and time zones, and relative and absolute times.
Unless otherwise specified, the default input and output parameters are as
follows:
+ If NULL is specified for a utc input parameter, the current time is
used.
+ If NULL is specified for any output parameter, no result is returned.
RELATED INFORMATION
Books: OSF DCE Application Development Guide
Additional Information (explode) :
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