[rules-users] Events in wrong order - will it cause problems?

[Wolfgang Laun]

You might be bitten by incorrect firings of rules that react to
something not happening after some event. Consider the rule:

  "When John doesn't call Betty after he calls Ada and before he calls Cloe..."

and the call event to Betty arrives later than the one to Cloe.

(There may be issues with window:time, too, due to long transmission delays.)

It depends on the application, but overwriting timestamps of the
source device might be necessary, possibly with a check of the length
of the transmission delay. Some mobile services are not guaranteed to
be anywhere near real time.

-W

On 10/09/2013, Alexander Wolf <mail at alexander-wolf.net> wrote:
> I used to let drools  set the timestamp of events automatically, but a new
> requirement forces me to use @timestamp for my events.
> Normally my events should come in the right order, but sometimes (as the
> events origin from mobile devices) it can occur that the order is
> incorrect.
>
> I tested with "wrong" timestamps and it seems like they would work alright -
> but I think I read somewhere, that events inserted in a wrong order might be
> ignored in some circumstances (especially by CEP rules).
>
> How can events in wrong order cause problems?
>
>
>