On-Rev and Daylight Savings Time (Addendum)

[Jim Ault]

Caution:
You can change the time that Rev (or any program) gets on your  
computer by simply setting your computer clock to anything you like.   
The same thing can happen on any computer or server.  Just ask a large  
company that has servers in different cities and countries.

The key to iRev servers is that they are probably extremely stable and  
constantly updated to one of the atomic clock sites.
One issue of daylight savings (especially in the state of Indiana) is  
that some counties will change their clocks and others will not.

Another issue is that the last daylight savings change in the Spring  
was done one week later in the UK than in the US.  The result was two  
time changes 7 days apart.

A computer program running on a processor can have functions that ask  
the processor for date and time info, but daylight savings changes are  
external to the processor.
If you write a function that gets the seconds at midnight each day,  
then see if it is 24.0 hours after the previous midnight, you know the  
processor has not changed the time zone or time shift in its control  
panel settings.

If you have a local processor and one at iRev, you need to track this  
for each processor and maintain the correct offset ( +1, -1, 0 ).  You  
might want to study GMT options and use one of those.

Hope this helps.

Jim Ault


On Aug 31, 2009, at 8:07 PM, Gregory Lypny wrote:

> Just a little more detail on my previous post.  Would appreciate  
> anyone confirming that iRev does not adjust for local Daylight  
> Savings Time or I've misunderstood something because this has the  
> potential to really mess up my work if I get it wrong.
>
> There's a difference of one hour as this code in iRev
>
> <?rev
> put the seconds & "</br>"
> convert the seconds to dateItems
> put it & "</br>"
> put the long time
> ?>
>
> returns
>
> 1251773601
> 2009,8,31,21,53,21,2
> 9:53:21 PM
>
> and the equivalent handler in Revolution
>
> put the seconds
> convert the seconds to dateItems
> put return & it after msg
> put return & the long time after msg
>
> run three seconds later, returns
>
> 1251773604
> 2009,8,31,22,53,24,2
> 10:53:24 PM
>
> Sigh,
>
> 	Gregory
> 	Frustrated in Montreal (DST)
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Jim Ault
jimaultwins at yahoo.com