[rules-users] Matching consecutive events

[Edson Tirelli]

   Hi Jaro,

   This might be a side effect of the temporal reasoning algorithm when
using unbounded intervals like you are doing (i.e., using before and after
operators without an interval parameter). Assuming this is what is
happening, the activation is probably scheduled, but it only happens when
the next activity is about to happen inside the session.

   With the current version, I can only suggest two workarounds. Either:

* Use straight relational operators in your rule (>, <). E.g.:

        $ev2 : LocalizationEvent( ..., timestamp > $ev1.timestamp ) ...

* Or, try to use bounded temporal operators. E.g.:

        $ev2 : LocalizationEvent( ... this after[0,60s] $ev1 ) ...

    We know it is not ideal, and for the next Drools release we are
implementing explicit sequence operators where you will be able to just
define [strict] sequencing. E.g.:

when
 $ev1 : LocalizationEvent( ... ) =>
 $ev2 : LocalizationEvent( ... )
then
...

     Details here:

https://community.jboss.org/wiki/EventSequencing#4_Definition_Sequence_Conditional_Elements

     Edson
On Wed, Aug 1, 2012 at 5:52 AM, jpullmann <
jaroslav.pullmann at fit.fraunhofer.de> wrote:

> Dear contributors,
>
>   this rule is expected to match a sequence of 2 consecutive events:
>
> rule "test"
>     when
>         // a)
>         $ev1 : LocalizationEvent( type == TYPE.HINT,  $target : target  )
> from entry-point "events/localization"
>         $ev2 : LocalizationEvent( type == TYPE.HINT, target == $target,
> this
> after $ev1 ) from entry-point "events/localization"
>         // b)
>         // Ev1 directly followed by ev2: no other HINT in between
>         not( LocalizationEvent( type == TYPE.HINT, target == $target, this
> after $ev1, this before $ev2 )  from entry-point "events/localization" )
>     then
>       do()
> end
>
>  The second event is interpreted as a "confirmation" of the first event
> (a).
>  No other (deviating) event is allowed between them (b). With this
> restriction
>  in place, the rule requires a sequence of 3 input events for activation,
> otherwise
>  2 events are sufficient (as expected). The events are ordered correctly
> and
> it is
>  not obvious, why a third event is needed since the interval between ev1
> and
> ev2 is
>  closed ? This leads to an unnecessary delay in rule activation.. How could
> this be
>  avoided and are there other approaches to match a concrete event sequence
> pattern ?
>
>  Many thanks
>    Jaro
>
>
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/Matching-consecutive-events-tp4018980.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
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>



-- 
  Edson Tirelli
  JBoss Drools Core Development
  JBoss by Red Hat @ www.jboss.com
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