Daylight Saving Time (DST) - Impact on Software & Hardware Systems
This document discusses about the new provisions for Daylight Saving Time in the recently introduced energy bill in the US and its impact on software systems which use schedulers and electronic devices like VCR, DVD players, energy meters etc that has got inbuilt calendars.
Introduction
Many non tropical countries which experience wide swing in the day light time during the year set their clocks forward in summer and then revert it back in winter, ostensibly to save energy. This exercise is called Daylight Saving Time (or Summer Time).
The recently introduced energy bill in US senate calls for, with effect from 2007, daylight savings to begin three weeks earlier, on the second Sunday in March, and to end on the first Sunday in November, one week later than daylight saving time currently does.
This necessitates a small tweak or a revisit in the case of software and gadgets that now compensate for daylight time based on a schedule unchanged since 1987. The upcoming transition evokes memories of Y2K, the Year 2000 rollover that forced programmers to adjust software and other systems that, relying on two digits for the year, never took the 21st century into account.
Daylight Saving Time (DST)
Strictly speaking, the term Daylight Saving Time or DST is a misnomer. No daylight can be saved by changing the hours of the day. The sun sets at the same time in the evening on any given day, no matter what we call that time. When we move the clock forward in spring/summer, we indeed have more light after work to enjoy outdoor activities and that may result in saving electricity.
Citing U.S. Department of Transportation studies it is projected that the extension of daylight savings in springtime might result in electricity savings of 1 percent in March and April, equivalent to roughly a hundred thousand barrels of oil daily over the two months.
The Impact on Software & Hardware
A total of four-week extension of daylight-saving time (DST) on either side of the current scheduling could trip up applications and gadgets programmed to adjust their internal clocks according to the "summer time" schedule the U.S. has kept for nearly two decades.
Software
The nonprofit Calendaring and Scheduling Consortium, which includes leading universities, software giants like Oracle, and even NASA's Jet Propulsion Laboratory, has prepared an advisory document for Congress. The statement warns that the current bill does not allow for enough time to prepare the United States' computer-based scheduling systems. In addition, computer groups are raising fears that the extension could cause wide-scale scheduling snafus. The worst affected will be airline booking and airline operations.
Programmers will once again need to check over their software code for potential problems handling a calendar adjustment. Many applications rely on the operating system to maintain an accurate clock, meaning Microsoft will play a critical role in keeping the world's computers running on time if DST hours change.
Computers with Microsoft Corp.'s Windows operating systems would need to obtain updates. Though most affected applications would likely be taken care of by the Microsoft fix, calendar systems will need to be checked to ensure that appointments already entered get properly adjusted.
Adding to the complications is the fact that many computer programs now treat U.S. and Canadian time zones as the same. If Canada doesn't adopt the new dates, too, Windows, calendars and other software would have to learn additional zones.
More complex networks of computers, such as systems that run power plants or financial institutions, would likely have to undertake more intense reprogramming, which could prove costly. These systems are generally nonstandard and so they're unique to that institution.
Hardware
When daylight-saving time starts earlier than usual in the United States come 2007, your VCR or DVD recorder could start recording shows an hour late. Cell phone companies could give you an extra hour of free weekend calls. Equipments, which rely on timestamps, will be affected the most.
Newer VCRs and DVD recorders have built-in calendars to automatically adjust for daylight time. Users would have to override them, switching to "manual" to ensure shows continue to record correctly.
Many systems have means for self-correction. Video recorders, for instance, can synch with time signals sent over PBS broadcasts and through electronic programming guides. Some watches can adjust times based on radio signals from the U.S. National Institute of Standards and Technology and other government sources. The digital clocks on cell phones are generally synched with the service provider's network clock.
The Solution
For electronic devices there could be instances where skilled effort will be required to bring the changes. Most of the effort will be confined to firmware changes. But in certain cases there might be impact on other functionalities, which may call for deeper analysis and study.
It is recommended that any embedded device, which does not have an inbuilt user programmable calendar, should incorporate a suitable, scaled down embedded calendar with in the processor and memory constraints. This will make the device immune to any DST changes in the future.
The Conclusion
Though a parallel is drawn with the gigantic Y2K problem, the threat that the looming DST change could pose is much scaled down. We're looking only at a one-hour difference versus setting back (the clock) 99 years and the Y2K problem was even powerful enough to make an entire system crash.
But for business savvy people this could even present another business opportunity. The sentiments are truly uncovered in the following rejoinder from a consultant who definitely would have missed the Y2K boat. “You might say there is nothing to really worry about here, but all the more reason to sell yourself to clients,” the consultant quipped. “If there is no real threat, there is no danger you will fail.”