4:53 a.m.
Let's say I have two independent streams of different events: EventA and
EventB. Which is the best way to get all the occurrences of EventB that
happened between the last 3 occurrences of EventA?
For example:
from:
$b1:EventB, $a1:EventA, $b2:EventB, $b3:EventB, $a2:EventA,
$b4:EventB, $b5:EventB, $a3:EventA, $b6:EventB
I would like to get $b2, $b3, $b4, $b5
Best Regards,
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Esteban Aliverti
- Blog @ http://ilesteban.wordpress.com
5:17 a.m.
Use "wrapper" or "marker" facts to identify the last three
EventA's
and a rule to "push" EventA's through these markers. Then, a simple
rule will give you all EventBs between the extremes of the marker set.
Take care to get the start-up right ;-)
-W
On 07/01/2013, Esteban Aliverti <esteban.aliverti(a)gmail.com> wrote:
Let's say I have two independent streams of different events:
EventA and
EventB. Which is the best way to get all the occurrences of EventB that
happened between the last 3 occurrences of EventA?
For example:
from:
$b1:EventB, $a1:EventA, $b2:EventB, $b3:EventB, $a2:EventA,
$b4:EventB, $b5:EventB, $a3:EventA, $b6:EventB
I would like to get $b2, $b3, $b4, $b5
Best Regards,
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Esteban Aliverti
- Blog @ http://ilesteban.wordpress.com
6:14 a.m.
Thanks Wolfgang.
I was trying to solve the whole situation with just 1 rule, but not I'm
trying to separate the problem in multiple rules. There are some
bugs/language-limitations/programmer-skills-limitations that are preventing
me to get the expected results though.
Let's say I have a rule identifying my last 3 EventA (ALL my facts are
declared as events):
declare Last3A
@role(event)
firstEvent: EventA
lastEvent: EventA
end
rule 'Detect last 3'
when
//some magic using sliding windows
then
//$firstEventA and $lastEventA are the bounds identified in the LHS of
the rule.
//EventA class doesn't have an explicit timestamp (drools is providing
it) and I'd prefer to leave it that way.
insert (new Last3A($fistEventA, $lastEventA));
end
Then I have my rule trying to get the occurences of EventB that happen
during a Last3A
rule 'Get EventBs'
when
$l: Last3A()
//originally, I've used a collect here since I wanted a single
activation, but I'll use a single event here just to make syntax cleaner.
EventB(this after $l.firstEvent,this before $l.lastEvent)
then
...
end
If I try the latter rule, after I insert the third EventA (I'm calling
fireAllRules() after each insertion) I get the following exception:
*Exception executing consequence for rule "Detect last 3" in com.whatever:
java.lang.ClassCastException: com.whatever.EventA cannot be cast to
java.lang.Number*
*...*
*Caused by: java.lang.ClassCastException: **com.whatever.EventA** cannot be
cast to java.lang.Number
*
*at
org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:341)
*
I'm assuming Drools is trying to cast the result of $l.firstEvent into a
number (probably because it is expecting a timestamp) even though the
result is already an Event.
In order to avoid the $l.firstEvent and $l.lastEvent invocations I re-wrote
the rule as follows (is ugly, I know):
rule 'Get EventBs'
when
$l: Last3A()
$firstEvent: EventA() from $l.getFirstEvent()
$lastEvent: EventA() from $l.getLastEvent()
EventB(this after $firstEvent,this before $lastEvent)
then
...
end
The exception now is:
*Exception executing consequence for rule **"Detect last 3"** in
com.cognitive.nsf.management: java.lang.ClassCastException:
org.drools.common.DefaultFactHandle cannot be cast to
org.drools.common.EventFactHandle*
*
*
What is happening now is that Drools doesn't realize that the object I'm
using for after and before are actually Events.
So it seems that temporal operators can only be used with events coming
from the same rule (and not coming from a 'from' or any other black box).
I'll continue digging on this, but it seems that the only solution will be
to use explicit time stamps and then use them instead of the events in my
marker fact.
Best Regards,
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Esteban Aliverti
- Blog @ http://ilesteban.wordpress.com
On Mon, Jan 7, 2013 at 12:17 PM, Wolfgang Laun <wolfgang.laun(a)gmail.com>wrote:
Use "wrapper" or "marker" facts to identify the
last three EventA's
and a rule to "push" EventA's through these markers. Then, a simple
rule will give you all EventBs between the extremes of the marker set.
Take care to get the start-up right ;-)
-W
On 07/01/2013, Esteban Aliverti <esteban.aliverti(a)gmail.com> wrote:
> Let's say I have two independent streams of different events: EventA and
> EventB. Which is the best way to get all the occurrences of EventB that
> happened between the last 3 occurrences of EventA?
>
> For example:
>
> from:
> $b1:EventB, $a1:EventA, $b2:EventB, $b3:EventB, $a2:EventA,
> $b4:EventB, $b5:EventB, $a3:EventA, $b6:EventB
>
> I would like to get $b2, $b3, $b4, $b5
>
> Best Regards,
>
>
>
>
> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>
> Esteban Aliverti
> - Blog @ http://ilesteban.wordpress.com
>
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rules-users(a)lists.jboss.org
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8:16 a.m.
OK, so this is how I'd do it:
rule "shift EventA"
no-loop
when
$triple: Last3A()
$eva: EventA()
then
modify( $triple ){
setFirst( $triple.getSecond() ),
setSecond( $triple.getThird() ),
setThird( $eva )
}
end
rule "find in-between"
when
$triple: Last3A($first: first, $third: third )
$eva1: EventA( this == $first )
$eva3: EventA( this == $third )
$evb: EventB( this after $eva1 before $eva3 )
then
...
end
If you need all EventB's in a single Collection, use accumulate.
I haven't tried to locate the cause of the CCE, but I think it's due
to using an object of type Event from a field in Last3A in an
operation where there ought to be a timestamp. Probably some fall-back
reaction of the implementation of the temporal operator, might have to
read the Java code to be sure...
-W
On 07/01/2013, Esteban Aliverti <esteban.aliverti(a)gmail.com> wrote:
Thanks Wolfgang.
I was trying to solve the whole situation with just 1 rule, but not I'm
trying to separate the problem in multiple rules. There are some
bugs/language-limitations/programmer-skills-limitations that are preventing
me to get the expected results though.
Let's say I have a rule identifying my last 3 EventA (ALL my facts are
declared as events):
declare Last3A
@role(event)
firstEvent: EventA
lastEvent: EventA
end
rule 'Detect last 3'
when
//some magic using sliding windows
then
//$firstEventA and $lastEventA are the bounds identified in the LHS of
the rule.
//EventA class doesn't have an explicit timestamp (drools is providing
it) and I'd prefer to leave it that way.
insert (new Last3A($fistEventA, $lastEventA));
end
Then I have my rule trying to get the occurences of EventB that happen
during a Last3A
rule 'Get EventBs'
when
$l: Last3A()
//originally, I've used a collect here since I wanted a single
activation, but I'll use a single event here just to make syntax cleaner.
EventB(this after $l.firstEvent,this before $l.lastEvent)
then
...
end
If I try the latter rule, after I insert the third EventA (I'm calling
fireAllRules() after each insertion) I get the following exception:
*Exception executing consequence for rule "Detect last 3" in com.whatever:
java.lang.ClassCastException: com.whatever.EventA cannot be cast to
java.lang.Number*
*...*
*Caused by: java.lang.ClassCastException: **com.whatever.EventA** cannot be
cast to java.lang.Number
*
*at
org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:341)
*
I'm assuming Drools is trying to cast the result of $l.firstEvent into a
number (probably because it is expecting a timestamp) even though the
result is already an Event.
In order to avoid the $l.firstEvent and $l.lastEvent invocations I re-wrote
the rule as follows (is ugly, I know):
rule 'Get EventBs'
when
$l: Last3A()
$firstEvent: EventA() from $l.getFirstEvent()
$lastEvent: EventA() from $l.getLastEvent()
EventB(this after $firstEvent,this before $lastEvent)
then
...
end
The exception now is:
*Exception executing consequence for rule **"Detect last 3"** in
com.cognitive.nsf.management: java.lang.ClassCastException:
org.drools.common.DefaultFactHandle cannot be cast to
org.drools.common.EventFactHandle*
*
*
What is happening now is that Drools doesn't realize that the object I'm
using for after and before are actually Events.
So it seems that temporal operators can only be used with events coming
from the same rule (and not coming from a 'from' or any other black box).
I'll continue digging on this, but it seems that the only solution will be
to use explicit time stamps and then use them instead of the events in my
marker fact.
Best Regards,
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Esteban Aliverti
- Blog @ http://ilesteban.wordpress.com
On Mon, Jan 7, 2013 at 12:17 PM, Wolfgang Laun
<wolfgang.laun(a)gmail.com>wrote:
> Use "wrapper" or "marker" facts to identify the last three
EventA's
> and a rule to "push" EventA's through these markers. Then, a simple
> rule will give you all EventBs between the extremes of the marker set.
>
> Take care to get the start-up right ;-)
>
> -W
>
> On 07/01/2013, Esteban Aliverti <esteban.aliverti(a)gmail.com> wrote:
> > Let's say I have two independent streams of different events: EventA
> > and
> > EventB. Which is the best way to get all the occurrences of EventB that
> > happened between the last 3 occurrences of EventA?
> >
> > For example:
> >
> > from:
> > $b1:EventB, $a1:EventA, $b2:EventB, $b3:EventB, $a2:EventA,
> > $b4:EventB, $b5:EventB, $a3:EventA, $b6:EventB
> >
> > I would like to get $b2, $b3, $b4, $b5
> >
> > Best Regards,
> >
> >
> >
> >
> > XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
> >
> > Esteban Aliverti
> > - Blog @ http://ilesteban.wordpress.com
> >
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
8:45 a.m.
Great idea Wolfgang! I've already solved the problem using timestamps, but
I think your suggestion is more elegant. I'll give it a try as soon as I
have time.
Best Regards,
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Esteban Aliverti
- Blog @ http://ilesteban.wordpress.com
On Mon, Jan 7, 2013 at 3:17 PM, Wolfgang Laun <wolfgang.laun(a)gmail.com>wrote:
On 07/01/2013, Wolfgang Laun <wolfgang.laun(a)gmail.com> wrote:
> $evb: EventB( this after $eva1 before $eva3 )
Oops:
$evb: EventB( this after $eva1 && before $eva3 )
-W
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