Changing the timezone for ASP.Net App

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Victor Reboucas - 19 Dec 2006 16:11 GMT

Hi, I have a problem that I'm pretty sure is not an usual one

I have an asp.net app that's running in a server in Texas-US but I'm
operating the system in Brasil, this means that every time I have to deal
with the current date/time (now() function) I get the values from a timezone
that's different than the timezone the users are physically in.

I read about the system.timezone class but could not implement it the way I
want to, I mean, I was not able to "say to the system" "start operating in
GMT -3"

PS: I need to find a way to change the timezone used by the system per user
because just Brasil has 4 different timezones

PS2: In another system I've developed I implemented a solution using a value
stored in the app.config file with the number of hours I have to apply to
correct the current date/time. This kind of approach is kind of very poor
because I'm forced to operate in a single timezone and perform a lot of
calculations along the system, what get's me more work than solution to deal
with the problem

If some one have any clue...

Thanks a lot,
Victor

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Aldo Donetti [MS] - 20 Dec 2006 01:23 GMT

Hi Victor, I don't think it's an unusual scenario.
I think a good approach (same as the one Outlook Web Access uses) is to
profile your users and allow them to select a Timezone that gets stored
with it.
So when they get authenticated you already know how much to add/subtract to
the UTC-converted datetime. Of course this goes along with the
recommendation of converting/storing all of your datetimes on the server in
UTC format so it's easier to so add/subtract the delta. (delta is from UTC,
which is independednt of the location of your server)

HTH,
Aldo

-- This posting is provided "AS IS" with no warranties, and confers no
rights.

--------------------

| From: "Victor Reboucas" <vcreb@hotmail.com>
| Subject: Changing the timezone for ASP.Net App
[quoted text clipped - 25 lines]
| Thanks a lot,
| Victor

Reply to this Message

Victor Reboucas - 21 Dec 2006 14:27 GMT

Ok, I can store the UTC per user, but, can I use the system.timezone to
correct the date/time or this object has nothing to do with ASP.Net
globalization process?

I mean, if you set the Culture or UICulture you get the ASP.Net
globalization features working, but, can I set a system.timezone parameter
for the Culture object to correct the dates?

All I don't want to do is to implement is all these calculations...

PS: I may be searching for a feature that does not exist (at least I did not
found it yet), but, since I started developing apps using .Net in version
1.0 there's a rule of thumb I always follow: "when a thing starts getting
too complicated (too much code for little tasks), study a little bit more
and you'll find a way to solve the problem using .Net itself" - I'm just not
sure if this rule applies here...

Thanks a lot,
Victor

> Hi Victor, I don't think it's an unusual scenario.
> I think a good approach (same as the one Outlook Web Access uses) is to
[quoted text clipped - 55 lines]
> | Thanks a lot,
> | Victor

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Aldo Donetti [MS] - 28 Dec 2006 03:14 GMT

Hi Victor, I think you are out of luck in this case.

As you can see the BCL team has been asking for scenarios for
implementations of new methods in the TimeZone class
<http://blogs.msdn.com/bclteam/archive/2006/07/05/657242.aspx>

And they have started implementing TimeZone conversions for Orcas
<http://blogs.msdn.com/bclteam/archive/2006/10/03/System.TimeZone2-Starter-G
uide-_5B00_Kathy-Kam_5D00_.aspx>

But in your case you should not need that, because *roughly* you only need
(a) to convert .ToUniversalTime() when you store dates/times on the server
and (b) add to these dates/times the delta for each user before you display
them

A few more interesting articles
- DateTime structure + please notice the added comment and the link at the
bottom of the article
<http://msdn2.microsoft.com/en-us/library/system.datetime(VS.80).aspx>
- Webservices and Timezones
<http://blogs.msdn.com/suryaj/archive/2006/03/29/564322.aspx>

HTH
Aldo

-- This posting is provided "AS IS" with no warranties, and confers no
rights.

--------------------

| From: "Victor Reboucas" <vcreb@hotmail.com>
| References: <ua34ge4IHHA.3872@TK2MSFTNGP06.phx.gbl>

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| Subject: Re: Changing the timezone for ASP.Net App
| Date: Thu, 21 Dec 2006 12:24:09 -0300
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Changing the timezone for ASP.Net App

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