The Inner Drive Extensible Architecture™—the Idea™

Demonstration: Time zones

The IDEA™ includes a fully-object-oriented, easy-to-integrate set of tools to allow you to use the Internet-standard tzinfo database—used throughout the world on millions of Unix computers—in your .NET apps.

Explore time zones

We've loaded 495 time zones for you to check out:

Choose a world region
Find the zone name
Current time

UTC	Wednesday, July 18, 2018 12:30:16 AM UTC
Inner Drive HQ	Tuesday, July 17, 2018 7:30:16 PM CDT
America/Chicago	Tuesday, July 17, 2018 7:30:16 PM CDT

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How this works

The time zone handling classes are in the InnerDrive.Geography assembly. Most are internal to the assembly; generally, you only need to work with the TimeZoneFactory class. The factory parses the raw tzinfo database and makes it available through a singleton instance.

First, the App.config or Web.config file (or wherever you store app settings) needs the following keys:

<?xml version="1.0"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
   <appSettings>
      <add key="DefaultTimeZoneRuleFile" value="C:\Source\InnerDrive\Utilities\tzinfo database\northamerica"/>
      <add key="DefaultTimeZoneHomeZone" value="America/Chicago"/>
      <add key="TimeZoneRuleFolder" value="C:\Source\InnerDrive\Utilities\tzinfo database"/>
      <add key="TimeZoneRuleFileFull" value="europe,northAmerica,pacificnew,southamerica,
		africa,antarctica,asia,australasia,backward,etcetera,leapseconds,solar87" />
   </appSettings>
</configuration>

At application start, the factory initializes. The Application_Start event handler calls this method:

private static void LoadTimeZones()
{
   var fileSpecListRaw = ConfigurationManager.AppSettings[TimeZoneFactory.DefaultTimeZoneRuleFileListSettingKey];
   var fileSpecList = fileSpecListRaw.Split(',');
   var dataFolder = ConfigurationManager.AppSettings[TimeZoneFactory.DefaultTimeZoneRuleFolderSettingKey];
   try
   {
      TimeZoneFactory.Instance.LoadTzInfoFiles(dataFolder, fileSpecList);
   }
   catch (InvalidTimeZoneException itex)
   {
      // log the exception
   }
   // other exceptions elided
}

(By default, the factory will not throw an exception if a time zone definition is corrupt. The time zone will be unavaliable, however.)

At this point, you can use the default time zone—on this site, "America/Chicago", UTC-05:00—in one method call:

var thisZone = TimeZoneFactory.DefaultTimeZone;
var localTime = thisZone.ToLocalTime(DateTimeOffset.UtcNow);

Using a different zone is almost that easy. You simply call the TimeZoneFactory.FindZone method with the name of the zone you want. Here's the code from this page's code-behind:

private void SetLocalTime()
{
   var localZone = SelectedZone;
   resultPrompt.Text = localZone.Name;
   SetText(localZone, resultText);
}

private void SetText(IdtTimeZone timeZone, ITextControl control)
{
   var currentInfo = timeZone.CurrentInfo(SelectedTime);
   control.Text = string.Format(CultureInfo.CurrentCulture, "{0:D} {0:T} {1}",
      currentInfo.LocalTime,
      currentInfo.Abbreviation);
}

Behind the scenes, time zone information is cached, making lookups very fast, and saving the trouble (and computing resources) of loading the tzinfo database again.

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