[UR-WG] Comment on duration format for WallDuration andCpuDuration

[Donal K. Fellows]

Bart Heupers wrote:
> If you add the start date you still don't know how long it is. 
>     2005-08-09T18:31:42P6M4DT12H30M17S 
> How many seconds is that?

You are aware that that is an underspecified time? The timezone is
omitted, and even with that you still would not know what DST rules to
apply. And that's leaving aside the problems you've identified too. All
this just goes to show that time arithmetic is hard, and best left to
libraries where someone else has sorted out all the problems.

[...]
> Then the ISO8601 specification is not ambiguous. But I would prefer to
> use seconds.

It's not ambiguous. It's your "normalization" code that is wrong. :-)
False normalization of values causes real trouble; it is not possible to
do this correctly with durations, and because of this, if normalization
is to be done, it must be done immediately before display to a real
user, and not at any intermediate stage.

If you want to use seconds, do so:
   PT<YourNumberGoesHere>S
If you wish, within your Grid, to profile (i.e. restrict) the use of the
usage record to require that durations are always expressed only using
seconds, you can do just that.

Donal.