[jp] Goodbye, and thanks for all

James E. LaBarre j.e.labarre at gmail.com
Wed Jul 17 08:01:28 EDT 2013


On 07/16/2013 06:12 PM, Jack Haverty wrote:
> Time-stamping is not good enough.  In my example, both parties changed
> the event to be 1-1/2 hours, so no matter who wins the result will be
> 1-1/2.  But the correct value is 2 hours.
>
> In database lingo, this gets into "Distributed Transaction Processing" -
> a Hard part of that Real Hard Problem.  However, this is pretty much a
> solved problem.  That's what databases do. The question is when and if
> that technology will make it to PDAs and such.  Meanwhile, as you say,
> we have to be careful and follow some rules.
>
> A "change history" can help.  But apps also have to be designed with
> knowledge of the distributed nature.  For example, a "change" primitive
> which allows you to "change the beginning and end times" of an
> appointment isn't able to solve the scenario I outlined and always get
> the right answer.   A different primitive, to "change the duration by X
> minutes" of an appointment, could get the right answer.  I think.
> Maybe.  It's a hard problem...

In Lotus Notes they have "replication conflict" entries, where both 
versions of a record get posted with a warning it's a conflict.




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