Question

I’m placed in a situation where my program has 2 integrations towards 3rd party systems. The integrations consists of 1) XML protocol over TCP/IP and 2) Webservices made in WCF.

In either case the integration partner needs the TimeStamps / DateTimes I pass to them to contain information about the TimeZone and Daylight Savings, so they can display the correct time regardless of their customers TimeZone / Position.

I’d rather not change the current protocol, in either cases they expect DateTime, so my question is: Is it possible to pass the TimeZone and Daylight Savings information as a part of the DateTime?

Right now my timestamps looks like this:

2011-04-27T15:14:13.963

I would love to have it look something like this (I’m located in Denmark so we use CEST) and be able to transfer the information with a DateTime object

 2011-04-27T15:14:13.963 +01:00

However I do not know how I should accomplish this nor take into account the Daylight Savings Factor

Answer 1

Use UTC time and you can stick with DateTime. UTC is converted to local (or any other time) in-place. Also this solves problem with Daylight Saving Time. Using UTC is the best solution, I have had some expirience with it.

Small demo:

namespace TimeZoneTest
{
  using System;
  using System.Globalization;

  class Program
  {
      static void Main(string[] args)
      {
          // get local time
          DateTime localTime = DateTime.Now;
          Console.WriteLine(string.Format(
              CultureInfo.CurrentCulture, 
              "localTime = {0}, localTime.Kind = {1}", 
              localTime, 
              localTime.Kind));

          // get local time zone, or use TimeZoneInfo to get any time zone you want
          TimeZone ltz = TimeZone.CurrentTimeZone;
          Console.WriteLine(string.Format("local time zone = {0}", ltz.StandardName));

          // convert local time to UTC
          DateTime utcTime = ltz.ToUniversalTime(localTime);
          Console.WriteLine(string.Format(CultureInfo.CurrentCulture,
              "utcTime = {0}, utcTime.Kind = {1}",
              utcTime,
              utcTime.Kind));

          // transfer date via service, as ISO time string
          string isoUtc = utcTime.ToString("o");
          Console.WriteLine("...");
          Console.WriteLine(string.Format("transfer: isoUtc = {0}", isoUtc));
          Console.WriteLine("...");

          // now on the other side
          DateTime utcTimeRecieved = DateTime.ParseExact(
              isoUtc, 
              "o", 
              CultureInfo.InvariantCulture, 
              DateTimeStyles.RoundtripKind);
          Console.WriteLine(string.Format(CultureInfo.CurrentCulture, 
              "utcTimeRecieved = {0}, utcTimeRecieved.Kind = {1}", 
              utcTimeRecieved, 
              utcTimeRecieved.Kind));

          // client time zone, or use TimeZoneInfo to get any time zone you want
          TimeZone ctz = TimeZone.CurrentTimeZone;
          Console.WriteLine(string.Format("client time zone = {0}", ctz.StandardName));

          // get local time from utc
          DateTime clientLocal = ctz.ToLocalTime(utcTimeRecieved);
          Console.WriteLine(string.Format(
              CultureInfo.CurrentCulture,
              "clientLocal = {0}, clientLocal.Kind = {1}",
              clientLocal,
              clientLocal.Kind));

          Console.WriteLine("\nPress any key to exit..");
          Console.ReadKey();
      }
  }

}