Timestamp and UTC kind

Question

In my application i receive Time stamp and in c# code I convert into date and pass this date to execute the stored procedure .My application is placed in server machine. But when this date is printed in log i saw the date is receiving in server one day less. Below is my code to convert from time stamp to date,

DateTime fromDate = new DateTime(1970, 1, 1, 0, 0, 0, 0, System.DateTimeKind.Utc);
fromDate =fromDate.AddMilliseconds(1430159400000).ToLocalTime();

date is : '2015-04-28' But when in server it receive as '2015-04-27'. This i came to know when i print this date in log. What i am doing wrong here!. Any suggessions most welcome.

Regards Sangeetha

score 1 · Accepted Answer · answered May 22 '15 at 06:14

Well currently you're converting the UTC timestamp to the system-local time - and presumably your server is in a different time zone to you.

I would strongly advise you to log the UTC timestamp directly, in UTC. Whatever reads your logs can then convert it to a local time in whatever time zone you want, but it's a lot more portable that way:

you don't need to know what time zone the server was in in order to understand the logs
you can merge logs from multiple servers trivially
you don't get any periods of ambiguity where a given local time occurs twice due to a daylight saving transition
if you plot aspects of the logs on a graph or something similar, you don't end up with bizarre discontinuities again due to daylight saving transitions
your code behaves the same on your dev machine as on your servers

So, you should:

Remove the ToLocalTime call
Make sure that however you're logging the timestamp includes Z at the end, so that it's clear it's in UTC.
Make sure that you use the invariant culture for logging, to avoid conversion to non-Gregorian calendars

If you're storing timestamps in the database, I'd recommend storing those in UTC as well. Some kinds of date/time values are best stored in local time, but timestamps are more global, representing an instant in time, so UTC is a suitable zone to use for storage.

score 1 · Answer 2 · edited May 23 '17 at 11:58

Since you calculate your DateTime based on Unix time, your 1430159400000 milliseconds (1430159400 seconds) generates Mon, 27 Apr 2015 18:30:00 UTC.

And since you calculate your local time with ToLocalTime method, this adds your current time zone offset to this DateTime. I strongly suspect your current machine and your server has different time zones and even your current UTC offset is equal or more then +05:30, that's why your ToLocalTime generates a local time that belongs one day after.

Logging a DateTime values as Local might be ambiguous. You should never do that. You should always store your DateTime as UTC.

Please read the best practices for that kind of processing;

Daylight saving time and time zone best practices

Timestamp and UTC kind

2 Answers2