[LEAPSECS] Java JSR-310 TAIInstant class

[Warner Losh]

On 01/29/2011 02:00, Stephen Colebourne wrote:

> This is the Javadoc of the TAIInstant class:

>

> Please use this thread to discuss flaws in the Javadoc.

>

>

>   * An instantaneous point on the time-line measured in the TAI time-scale.

>   *<p>

>   * Most of the Time Framework for Java works on the assumption that

> the time-line is

>   * simple, there are no leap-seconds and there are always 24 * 60 * 60

> seconds in a day.

>   * Sadly, the real-life time-line is not this simple.

>   *<p>

>   * This class is an alternative representation based on the TAI time-scale.

>   * This scale is defined using atomic clocks and has proceeded in a

> continuous uninterrupted

>   * manner since its epoch of {@code 1958-01-01T00:00:00(TAI)}.


A second minor point: TAI does not exist before this point.  Proleptic 
TAI is used, but more often TT is used for epochs prior to the present.  
I'd just note here that a proleptic TAI is used for dates prior to the 
1958 epoch.


>   *<p>

>   * As there are no leap seconds, or other discontinuities, in TAI,

> this time-scale

>   * would make an excellent timestamp. While there are, at the time of

> writing, few

>   * easy ways to obtain an accurate TAI instant, it is relatively easy

> to obtain a GPS instant.

>   * GPS and TAI differ by the fixed amount of 19 seconds.

>   *<p>

>   * The duration between two points on the TAI time-scale is calculated

> solely using this class.

>   * Do not use the {@code between} method on {@code Duration} as that

> will lose information.

>   * Instead use {@link #durationUntil(TAIInstant)} on this class.

>   *<p>

>   * It is intended that most applications will use the {@code Instant} class

>   * which uses the UTC-SLS mapping from UTC to guarantee 86400 seconds per day.

>   * Specialist applications with access to an accurate time-source may

> find this class useful.

>

> Stephen

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