12:49 p.m.
Hi,
I'm working on thinking in Drools rules. Right now I'm trying to solve this:
The rule shall fire if _a special event occurs more than 3 times
within 1 hour_.
My _first thought of a solution_ was to count the count the detected
events using a counter. But the counter has to be a global variable,
hasn't it? And global variables are not to be used to frequently, aren't
they?
And global variables must always be initialized from outside the rules
file, don't they?
Because of these thoughts I've looked for a _different solution without
global variables_. I came up with:
function boolean valueExceededLimit(Set<Alarms> alarmSet) {
//....
}
rule "more than 3 occurs within 1 hour"
when
// event #1
$eventA : Value(
eval(parameterValueExceededLimit($eventA.getAlarms())) )
// event #2
$eventB : Value( this after[0ms,1h] $eventA &&
this != $eventA &&
eval(valueExceededLimit($eventB.getAlarms())) )
// event #3
$eventC : Value( this after[0ms,1h] $eventA &&
this != $eventA &&
this != $eventB &&
eval(valueExceededLimit($eventC.getAlarms())) )
// event #4 -> 4 > 3
$eventD : Value( this after[0ms,1h] $eventA &&
this != $eventA &&
this != $eventB &&
this != $eventC &&
eval(valueExceededLimit($eventD.getAlarms())) )
then
// ... do something ...
end
More than 3 is kind of a doable task. But I think of this solution as
heavy in case its needed to detect a larger number of events. I would be
thankful for other approaches to the problem.
Thanks :)
Tina
1:19 p.m.
Basic idea: associate a Watcher with each event.
class Watcher {
Value what;
int count = 1;
Set<Value> valueSet = new HashSet<Value>();
Watcher( Value first ){
valueSet.add( what = first );
}
//...
}
And now the rules:
rule attachWatcher
when
$event : Value( eval(parameterValueExceededLimit($eventA.getAlarms())) )
not( Watcher( what == $event ) )
then
insert( new Watcher( $event ) );
end
rule addEvent
when
$watcher : Watcher( $eventA : what, $set : valueSet )
$eventB : Value( this after[0ms,1h] $eventA &&
// this != $eventA && ### set
includes Watcher.what
eval(valueExceededLimit($eventB.getAlarms()) && ! $set.contains( this ) ) )
then
modify( $watcher ){
setValueList( $watcher.getValueSet().add( $eventB ),
setCount( $watcher.getCount() + 1 )
}
end
rule testLimit
when
$watcher : Watcher( count > Limit )
then
// raise hell,
// probably: get rid of all in $watcher.set, and $watcher
end
(What and count are somewhat redundant, but this avoids clumsy patterns.)
Watcher should be declared as Event, with @expires, so they'll disappear
with the (primary) Event each one is watching.
Cheers
-W
2010/8/5 Tina Vießmann <tviessmann(a)stud.hs-bremen.de>
Hi,
I'm working on thinking in Drools rules. Right now I'm trying to solve
this:
The rule shall fire if *a special event occurs more than 3 times within
1 hour*.
My *first thought of a solution* was to count the count the detected
events using a counter. But the counter has to be a global variable, hasn't
it? And global variables are not to be used to frequently, aren't they?
And global variables must always be initialized from outside the rules
file, don't they?
Because of these thoughts I've looked for a *different solution without
global variables*. I came up with:
function boolean valueExceededLimit(Set<Alarms> alarmSet) {
//....
}
rule "more than 3 occurs within 1 hour"
when
// event #1
$eventA : Value(
eval(parameterValueExceededLimit($eventA.getAlarms())) )
// event #2
$eventB : Value( this after[0ms,1h] $eventA &&
this != $eventA &&
eval(valueExceededLimit($eventB.getAlarms())) )
// event #3
$eventC : Value( this after[0ms,1h] $eventA &&
this != $eventA &&
this != $eventB &&
eval(valueExceededLimit($eventC.getAlarms())) )
// event #4 -> 4 > 3
$eventD : Value( this after[0ms,1h] $eventA &&
this != $eventA &&
this != $eventB &&
this != $eventC &&
eval(valueExceededLimit($eventD.getAlarms())) )
then
// ... do something ...
end
More than 3 is kind of a doable task. But I think of this solution as heavy
in case its needed to detect a larger number of events. I would be thankful
for other approaches to the problem.
Thanks :)
Tina
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3:31 p.m.
New subject: Another solution for: Detecting more than 3 occurrences within 1 hour
Thank you for this approach, Wolfgang. That sounds great. :)
I just have some further question about your solution.
#1
I'm thinking about an approach without the need modifying things outside
the drl file. Is something like that doable?
Because I have to create the watcher class? (I don't expect it to be,
but why not ask. ;))
#2
(What and count are somewhat redundant, but this avoids clumsy
patterns.)
Am I right that what and count have to be defined as global variables
and initialized using setGlobal() (from a part of the java application)?
#3
rule addEvent
when
$watcher : Watcher( $eventA : what, $set : valueSet )
$eventB : Value( this after[0ms,1h] $eventA &&
// this != $eventA && ### set
includes Watcher.what
eval(valueExceededLimit($eventB.getAlarms()) && ! $set.contains( this
) ) )
I'm sorry, could you explain to me the part of $eventB in sentences,
please? I've got confused by the comments... :(
Thank you very much! :)
Tina
> Basic idea: associate a Watcher with each event.
>
> class Watcher {
> Value what;
> int count = 1;
> Set<Value> valueSet = new HashSet<Value>();
> Watcher( Value first ){
> valueSet.add( what = first );
> }
> //...
> }
>
> And now the rules:
>
> rule attachWatcher
> when
> $event : Value( eval(parameterValueExceededLimit($eventA.getAlarms())) )
> not( Watcher( what == $event ) )
> then
> insert( new Watcher( $event ) );
> end
>
rule addEvent
when
$watcher : Watcher( $eventA : what, $set : valueSet )
$eventB : Value( this after[0ms,1h] $eventA &&
// this != $eventA && ### set
includes Watcher.what
eval(valueExceededLimit($eventB.getAlarms()) && ! $set.contains( this
) ) )
> then
> modify( $watcher ){
> setValueList( $watcher.getValueSet().add( $eventB ),
> setCount( $watcher.getCount() + 1 )
> }
> end
>
> rule testLimit
> when
> $watcher : Watcher( count > Limit )
> then
> // raise hell,
> // probably: get rid of all in $watcher.set, and $watcher
> end
>
(What and count are somewhat redundant, but this avoids clumsy
patterns.)
>
> Watcher should be declared as Event, with @expires, so they'll
> disappear with the (primary) Event each one is watching.
>
> Cheers
> -W
>
>
> 2010/8/5 Tina Vießmann <tviessmann(a)stud.hs-bremen.de
> <mailto:tviessmann@stud.hs-bremen.de>>
>
> Hi,
>
> I'm working on thinking in Drools rules. Right now I'm trying to
> solve this:
> The rule shall fire if _a special event occurs more than 3 times
> within 1 hour_.
>
> My _first thought of a solution_ was to count the count the
> detected events using a counter. But the counter has to be a
> global variable, hasn't it? And global variables are not to be
> used to frequently, aren't they?
> And global variables must always be initialized from outside the
> rules file, don't they?
>
> Because of these thoughts I've looked for a _different solution
> without global variables_. I came up with:
>
> function boolean valueExceededLimit(Set<Alarms> alarmSet) {
> //....
> }
>
> rule "more than 3 occurs within 1 hour"
>
> when
> // event #1
> $eventA : Value(
> eval(parameterValueExceededLimit($eventA.getAlarms())) )
> // event #2
> $eventB : Value( this after[0ms,1h] $eventA &&
> this != $eventA &&
>
> eval(valueExceededLimit($eventB.getAlarms())) )
> // event #3
> $eventC : Value( this after[0ms,1h] $eventA &&
> this != $eventA &&
> this != $eventB &&
>
> eval(valueExceededLimit($eventC.getAlarms())) )
> // event #4 -> 4 > 3
> $eventD : Value( this after[0ms,1h] $eventA &&
> this != $eventA &&
> this != $eventB &&
> this != $eventC &&
>
> eval(valueExceededLimit($eventD.getAlarms())) )
>
> then
> // ... do something ...
>
> end
>
>
> More than 3 is kind of a doable task. But I think of this solution
> as heavy in case its needed to detect a larger number of events. I
> would be thankful for other approaches to the problem.
>
>
> Thanks :)
> Tina
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org <mailto:rules-users@lists.jboss.org>
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
4:15 a.m.
2010/8/5 Tina Vießmann <tviessmann(a)stud.hs-bremen.de>
Thank you for this approach, Wolfgang. That sounds great. :)
I just have some further question about your solution.
#1
I'm thinking about an approach without the need modifying things outside
the drl file. Is something like that doable?
Because I have to create the watcher class? (I don't expect it to be, but
why not ask. ;))
The DRL language provides "declare" (see Section 4.7 in the Expert manual).
Metadata is described in the Fusion manual.
#2
(What and count are somewhat redundant, but this avoids clumsy patterns.)
Am I right that what and count have to be defined as global variables and
initialized using setGlobal() (from a part of the java application)?
No! See the Java snippet "class Watcher". (If you use declare, you'll have
to do the initializations after creation.)
#3
rule addEvent
when
$watcher : Watcher( $eventA : what, $set : valueSet )
$eventB : Value( this after[0ms,1h] $eventA &&
// this != $eventA && ### set
includes Watcher.what
eval(valueExceededLimit($eventB.getAlarms()) && ! $set.contains( this ) ) )
I'm sorry, could you explain to me the part of $eventB in sentences,
please? I've got confused by the comments... :(
If there is
a Watcher watching $eventA and with a set of related events $set,
and
a Value less than 1hr later than $eventA and with more alarms than limit and
Watcher's $set does not contain this Value
then...
The line I commented out isn't necessary as I propose to add the very 1st
event tied to the Watcher to this Watcher's list.
Thank you very much! :)
You're welcome.
-W
Tina
Basic idea: associate a Watcher with each event.
class Watcher {
Value what;
int count = 1;
Set<Value> valueSet = new HashSet<Value>();
Watcher( Value first ){
valueSet.add( what = first );
}
//...
}
And now the rules:
rule attachWatcher
when
$event : Value( eval(parameterValueExceededLimit($eventA.getAlarms())) )
not( Watcher( what == $event ) )
then
insert( new Watcher( $event ) );
end
rule addEvent
when
$watcher : Watcher( $eventA : what, $set : valueSet )
$eventB : Value( this after[0ms,1h] $eventA &&
// this != $eventA && ### set
includes Watcher.what
eval(valueExceededLimit($eventB.getAlarms()) && ! $set.contains( this ) ) )
then
modify( $watcher ){
setValueList( $watcher.getValueSet().add( $eventB ),
setCount( $watcher.getCount() + 1 )
}
end
rule testLimit
when
$watcher : Watcher( count > Limit )
then
// raise hell,
// probably: get rid of all in $watcher.set, and $watcher
end
(What and count are somewhat redundant, but this avoids clumsy patterns.)
Watcher should be declared as Event, with @expires, so they'll disappear
with the (primary) Event each one is watching.
Cheers
-W
2010/8/5 Tina Vießmann <tviessmann(a)stud.hs-bremen.de>
> Hi,
>
> I'm working on thinking in Drools rules. Right now I'm trying to solve
> this:
> The rule shall fire if *a special event occurs more than 3 times within
> 1 hour*.
>
> My *first thought of a solution* was to count the count the detected
> events using a counter. But the counter has to be a global variable, hasn't
> it? And global variables are not to be used to frequently, aren't they?
> And global variables must always be initialized from outside the rules
> file, don't they?
>
> Because of these thoughts I've looked for a *different solution without
> global variables*. I came up with:
>
> function boolean valueExceededLimit(Set<Alarms> alarmSet) {
> //....
> }
>
> rule "more than 3 occurs within 1 hour"
>
> when
> // event #1
> $eventA : Value(
> eval(parameterValueExceededLimit($eventA.getAlarms())) )
> // event #2
> $eventB : Value( this after[0ms,1h] $eventA &&
> this != $eventA &&
>
> eval(valueExceededLimit($eventB.getAlarms())) )
> // event #3
> $eventC : Value( this after[0ms,1h] $eventA &&
> this != $eventA &&
> this != $eventB &&
>
> eval(valueExceededLimit($eventC.getAlarms())) )
> // event #4 -> 4 > 3
> $eventD : Value( this after[0ms,1h] $eventA &&
> this != $eventA &&
> this != $eventB &&
> this != $eventC &&
>
> eval(valueExceededLimit($eventD.getAlarms())) )
>
> then
> // ... do something ...
>
> end
>
>
> More than 3 is kind of a doable task. But I think of this solution as
> heavy in case its needed to detect a larger number of events. I would be
> thankful for other approaches to the problem.
>
>
> Thanks :)
> Tina
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
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5023
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3 comments
2 participants
participants (2)
-
Tina Vießmann -
Wolfgang Laun