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

[Donal K. Fellows]

Rosario Michael Piro wrote:
> Then what about aggregation? How would you compute the total CPU time 
> "consumed" by a user within the last year if some of the records contain 
> only seconds while others use also days and months. In this use case you 
> have to convert somehow. Of course, you might have something like 
> P123DT1686255S ... but give that value to the management board of the 
> LCG and let's see what they'll tell you ... :o)
> 
> Let's face it, we can't get easily around ambiguity with ISO8601 
> periods. Again, I don't say we shouldn't use them, but we need to be 
> aware that there will always be use cases where they will be ambiguous.

We can precisely represent the ambiguity if necessary. If one site is
genuinely measuring chargable time in months, you're in trouble anyway
as mixing months and seconds is hard. If you squelch the problem in one
place (e.g. by forcing everything to be recorded in seconds) you just
end up with it popping up elsewhere (e.g. sites producing records with
inaccurate/incorrect durations).

Since there is no perfect solution, we'll go with xsd:duration as that
is good for other reasons (i.e. people will interpret it correctly when
they read the schema, and nobody is precluded from recording what they
want). The other advantage of this is that it means we get URv1 to the
GGF Editor sooner rather than later... :-)

Donal.