XML Schema and Timezones
I am writing a Windows Scheduling Service in C# that will use data in XML format to determine Scheduling information. This same file will be replicated globally and hence will be subject to timezone changes and daylight saving time. [my timezone values are just examples - they may not be correct!!] I was originally using the XSD dateTime data type to determine the date and time to perform a task, but this is limited when applied globally, because the offset (timezone) is based on local time and as soon as you replicate to some other timezone, the local time changes and so your scheduling information goes nuts. An example... We have a Scheduled item that is to be done on July 16th, 2002 at 2PM Scottish time. This is simple to express as July 16th, 2002 at 2PM GMT (summer has no daylight saving time). According to the XML Schema stanard (http://www.w3.org/TR/xmlschema-2/#dateTime) which uses the format "CCYY:MM:DDTHH:MM:SSZ" this could be written as : "2002:07:16T14:00:00Z" However, this standard format doesn't work too great because in the winter the local time in Scotland changes to 1 hour less than UTC and so the scheduled time should change to "2002:07:16T13:00Z" or 1PM GMT, but how do you know this from the above fomat? Sure, it tells you the date, so you can work out whether Daylight Saving Time applies, but you don't know what timezone it refers to - it is a bad mistake to assume the local timezone, because if i moved the Schedule information to Santiago, Chile and we assumed the local settings to determine the offset then on that date the UTC time would be "2002:07:16T08:00Z" - because here we are 8 hours behind GMT on that date. There needs to be some way of stating the target timezone so that the correct Daylight settings relative to UTC can be resolved. Something like this... "CCYY:MM:DDTHH:MM:SSZGXXXX" where at the end, GXXXX specifies the locale identifier of the originally scheduled time. Does that make any sense?? Has there been talk of this before... I never really thought much about it until i had to use it in my app!! Cheers, Steven Author "XML Application Development with MSXML 4.0" www.deltabis.com
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