and how-so-ever specialized the request be, Java (nor webMethods) provides a way to differentiate between the two!!
or for that matter, any other language reading computer clocks!! And you cant predict or calculate time based on astronomical observations.
Please note that Java returns UTC rather than GMT. (though the terms are interchanged in usage)
from Java Sun Date implementation
[INDENT]Although the Date class is intended to reflect coordinated universal time (UTC), it may not do so exactly, depending on the host environment of the Java Virtual Machine.
Most computer clocks are not accurate enough to be able to reflect the leap-second distinction.[/INDENT]
Some computer standards are defined in terms of Greenwich mean time (GMT), which is equivalent to universal time (UT). GMT is the “civil” name for the standard; UT is the “scientific” name for the same standard. The distinction between UTC and UT is that UTC is based on an atomic clock and UT is based on astronomical observations, which for all practical purposes is an invisibly fine hair to split. Because the earth’s rotation is not uniform (it slows down and speeds up in complicated ways), UT does not always flow uniformly. Leap seconds are introduced as needed into UTC so as to keep UTC within 0.9 seconds of UT1, which is a version of UT with certain corrections applied. There are other time and date systems as well; for example, the time scale used by the satellite-based global positioning system (GPS) is synchronized to UTC but is not adjusted for leap seconds.