No Time Zone Offset Applied

With no time zone offset applied, the client generates data with local date&time information and this data is sent to the server. Thus the server receives and processes an entry from Berlin reading 4pm, an entry from New York reading 9am and an entry from London reading 3am. Although all three entries were made at exactly the same point of time, the server sees them as spanning an interval of seven hours! For time zone dependent data this represents a serious breach of consistency.

Time Zone Offset Applied

Let's now apply a time zone offset to the situation above. With the time zone features enabled, the application knows that there is a time zone offset between the client and the server and applies this offset when the data is sent to the server. All data processing is then performed on the time zone corrected values.

The offset is calculated as a difference between the GMT time offset of the server location and each location's particular GMT time offset. The particular offsets also contain information on each location's daylight saving time rules, courtesy of Java time zone implementation.

Example: (+1:Berlin) - (-6:New York) = (+7:New York) Data entered in New York get corrected by a value +7 when sent to the application server in Berlin.