Usage of Dates and Times in Networked Applications

Standards

• ISO 8601

Terms and Expressions

Date

• date a specific date without time part
• ISO-8601 format: YYYY-MM-DD
• example: 2020-03-01 (March 1., 2020)

Time

• time a time without a specific date. E.g. 19:00:00
  • ISO-8601 format: hh:mm:ss[.sss] (24 hour clock)
• zone a time zone for a specific time. E.g. +01:00 (Central European Standard Time), where +/- is the offset from UTC.
  • ISO-8601 format: <time>+hh:mm
  • ISO-8601 format for an UTC time: <time>Z

Datetime

• datetime a time on a specific date. E.g. 2020-03-01T19:00:00+01:00

Scenario / Problem

Scenario: Often networked applications have requirements such as:

• select a date in a given date range. Examples:
  • when to start a contract: First date tomorrow
  • when to receive a delivery: First date tomorrow, last date one week from now
• register the datetime for a transaction

Instant

A precise instant in time. E.g. the launch of Apollo 11.

Local Date

A date without zone information. E.g. this does not correspond to a specific instant in time.

E.g. your birthday. This contains no zone information even though at the instant when you were born, the date was not the same all over the globe (unlesss born at the exact time UTC 12:00:00).

E.g. if born in Denmark on February 7., 2020 at 21:00:00 (2020-02-07T21:00:00+01:00) the time in Australia is February 8., 2020 06:00:00 (2020-02-08T06:00:00+10:00). But nonetheless your birthday is February 7.