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VB.Net GMT/UTC and server time (specifically Google Calendar)

Posted on 2011-09-02
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Last Modified: 2014-11-12
Hi

I am linking  a web application to my Google calendar. The user can add events to their calendar using application.

I have a problem with the difference between GMT/UTC/BST and server time. Things work locally fine until it is hosted on remote server.

When the user inputs a new calendar entry, and clicks "OK" to make a new event, Google calendar (or somewhere between VB submitting the event and Google creating it) adds 6 or 7 hours (depending on if in BST or GMT/UTC)

e.g. if user inputs 6am on website, the value stored in Google calendar is made 12 or 1pm

In web.config (and pages) I have set <globalization uiCulture="en" culture="en-GB" />

See code for what is submitted to Google service.

NOTE: I also send an email to myself after creating event, using same properties, and it shows the USER INPUTTED Date/time - which is correct;
also, the results retrieved from Google calendar are correct for older appointments (both locally and on server)  are correct. When I make a new entry locally this works)

So the only problem is when creating an event on the SERVER.

Thanks in advance for help
Dim postUri As New Uri(CALENDAR_URI)
Dim calendarService = New CalendarService("JSCalendar")
calendarService.setUserCredentials("myuser", "mypassword")
Dim ev As New Google.GData.Calendar.EventEntry
ev.Title.Text = eventTitle
ev.Content.Content = content

' Set a location for the event. 
Dim eventLocation As New Where()
eventLocation.ValueString = location
ev.Locations.Add(eventLocation)
Dim eventTime As New [When](start, endTime)
ev.Times.Add(eventTime)

'write to service
ev = calendarService.Insert(postUri, ev)

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Question by:rwallacej
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Accepted Solution

by:
Jacques Bourgeois (James Burger) earned 500 total points
ID: 36479720
I do not know the Google API, but usually, an application that expect to get times from everywhere around the world records it a UTC. Google knowing what they are doing, this is probably how they work.

The way to deal with date/times then, is to send the Universal Time to the server, something like the following:
start .ToUniversalTime

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start is then adjusted to universal time according to the time zone set in your computer.

When you want to read back a time value from the server, you do the reverse. You convert the UTC value to the time zone of the receiving station:
start = dateFromServer.ToLocalTime

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