DateTime serialization best practices in NET 3 5

Question

Some years ago, I had followed this MSDN article on DateTime usage best practices for building a .Net client on .Net 1.1 and ASMX web services, with SQL 2000 server as the backend. I can still remember all the serialization issues I had with DateTime and the testing effort it took for servers across different time zones.

Does anyone know of any similar best practices document available for new technologies like WCF and SQL server 2008, especially with the addition of new datetime types for storing time zone aware info.

Environment:
1. SQL server 2008 on Pacific Time.
2. Web Services layer on a different time zone.
3. Clients could be using .Net 2.0 or .Net 3.5 on different time zones. (But, if it makes it any easy, we can just force everyone to upgrade to .Net 3.5.)

Any good suggestions/best practices for the data types to be used in each layer?

Answer 1

One of the best ways to do this is by always passing the object as UTC, and converting to local time on the clients' side. That way, there is a common reference point for all clients.
You can call ToUniversalTime on the DateTime object for converting it to UTC. Then, when on the clients, just call ToLocalTime to get it in their respective current time zone.

Note: Clients will receive the datetime kind as Unspecified. So, doing DateTime.SpecifyKind(myUtcTime, DateTimeKind.Utc) instead of ToUniversalTime could be a better approach.