9:44 a.m.
Hi - I am a Drools newbie and I apologize in advance if the answer to my
question is intuitively obvious to the casual user.
I have an object that has two fields: location(there are more than 50
locations) and age. I am having difficulty building clean rules for the
following pseudo-code
// Rule One
if(location == "A") {
if(age > 60)
do_something();
}
// Rule Two
else if(location == "B") {
if(age > 70)
do_something();
}
// Rule Three
else if(location == "C") {
if(age > 80)
do_something();
}
// Rule Four
else {
if(age > 65)
do_something();
}
The issue comes with Rule Four. How do I avoid writing the rule so that I
don't have to say
(location!="A"&&location!="B"&&location!="C")
? I also
don't want to have to write an explicit rule for every possible location.
I considered an activation-group with salience to have the rules executed
in order, but the problem is that if rules 1-3 do not fire, then rule 4
fires for all locations - I can get a hit if location=="C" and age==70.
Is it possible to have a 'Map' and do something like
(age>map.get(location)) ? I could live with creating a map with all
possible locations for key, although I'd rather not go this route.
This problem is typical for the types of rules I'll be writing ... there
can be completely different sets of rule criteria depending on location.
Thanks in advance for your suggestions and your patience.
10:14 a.m.
Hi,
If you do not want to check for all alternative cases, you might need a
showstopper to stop the firings of unwanted rules.
This can be achieved by executing insert(new ShowStopper() ); in your RHS.
All LHS of the rules will check for not( ShowStopper() )
Alternatively, you can use the new -experimental - feature of drools called
"declarative agenda". You could use this to block activations of rules
directly.
Also, be aware that relying on salience alone is very hard to maintain over
time.
Regards,
Frank
ronalbury wrote
Hi - I am a Drools newbie and I apologize in advance if the answer to my
question is intuitively obvious to the casual user.
I have an object that has two fields: location(there are more than 50
locations) and age. I am having difficulty building clean rules for the
following pseudo-code
// Rule One
if(location == "A") {
if(age > 60)
do_something();
}
// Rule Two
else if(location == "B") {
if(age > 70)
do_something();
}
// Rule Three
else if(location == "C") {
if(age > 80)
do_something();
}
// Rule Four
else {
if(age > 65)
do_something();
}
The issue comes with Rule Four. How do I avoid writing the rule so that I
don't have to say
(location!="A"&&location!="B"&&location!="C")
? I also
don't want to have to write an explicit rule for every possible location.
I considered an activation-group with salience to have the rules executed
in order, but the problem is that if rules 1-3 do not fire, then rule 4
fires for all locations - I can get a hit if location=="C" and age==70.
Is it possible to have a 'Map' and do something like
(age>map.get(location)) ? I could live with creating a map with all
possible locations for key, although I'd rather not go this route.
This problem is typical for the types of rules I'll be writing ... there
can be completely different sets of rule criteria depending on location.
Thanks in advance for your suggestions and your patience.
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rules-users mailing list
rules-users@.jboss
https://lists.jboss.org/mailman/listinfo/rules-users
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10:19 a.m.
Or you can use Guvnor tables and "otherwise" special value (see doc on
tables under guvnor)
Le 23/11/2011 17:14, FrankVhh a écrit :
Hi,
If you do not want to check for all alternative cases, you might need a
showstopper to stop the firings of unwanted rules.
This can be achieved by executing insert(new ShowStopper() ); in your RHS.
All LHS of the rules will check for not( ShowStopper() )
Alternatively, you can use the new -experimental - feature of drools called
"declarative agenda". You could use this to block activations of rules
directly.
Also, be aware that relying on salience alone is very hard to maintain over
time.
Regards,
Frank
ronalbury wrote
> Hi - I am a Drools newbie and I apologize in advance if the answer to my
> question is intuitively obvious to the casual user.
>
> I have an object that has two fields: location(there are more than 50
> locations) and age. I am having difficulty building clean rules for the
> following pseudo-code
>
>
> // Rule One
> if(location == "A") {
> if(age> 60)
> do_something();
> }
> // Rule Two
> else if(location == "B") {
> if(age> 70)
> do_something();
> }
> // Rule Three
> else if(location == "C") {
> if(age> 80)
> do_something();
> }
> // Rule Four
> else {
> if(age> 65)
> do_something();
> }
>
> The issue comes with Rule Four. How do I avoid writing the rule so that I
> don't have to say
(location!="A"&&location!="B"&&location!="C")
? I also
> don't want to have to write an explicit rule for every possible location.
>
> I considered an activation-group with salience to have the rules executed
> in order, but the problem is that if rules 1-3 do not fire, then rule 4
> fires for all locations - I can get a hit if location=="C" and age==70.
>
> Is it possible to have a 'Map' and do something like
> (age>map.get(location)) ? I could live with creating a map with all
> possible locations for key, although I'd rather not go this route.
>
> This problem is typical for the types of rules I'll be writing ... there
> can be completely different sets of rule criteria depending on location.
>
>
> Thanks in advance for your suggestions and your patience.
>
> _______________________________________________
> rules-users mailing list
> rules-users@.jboss
> https://lists.jboss.org/mailman/listinfo/rules-users
>
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12:19 p.m.
Try this:
rule 'Rule One'
activation-group 'age-test'
salience 300
when
Person (location == 'A', age > 60 )
Then
do_something();
end
rule 'Rule Two'
activation-group 'age-test'
salience 200
when
Person (location == 'B', age > 70 )
Then
do_something();
end
rule 'Rule Three'
activation-group 'age-test'
salience 100
when
Person (location == 'C', age > 80 )
Then
do_something();
end
rule 'Rule Else'
activation-group 'age-test'
when
Person (age > 65 )
Then
do_something();
end
This will do what you want, and the first rule that matches will cancel the activation of
any other rules that matches. However, because these rules are not mutually exclusive,
this is not the best way to represent the logic, since a change to person could cause the
wrong rule to fire, since only the rules that are affected by the change would be
re-activated.
The EASIEST way to represent this is with an Excel Spreadsheet (or the Guvnor Decision
Table). Then you can craft the table to identify each rule exclusively, and use the
otherwise keyword to deal with the negation of all specified facts. If you can represent
your rules without requiring salience as the conflict resolver, then you will have better
(more predictable) rules, since this would mean that only one of the group rules could
ever be true at any instance in proessing.
-----Original Message-----
ronalbury wrote
> Hi - I am a Drools newbie and I apologize in advance if the answer to my
> question is intuitively obvious to the casual user.
>
> I have an object that has two fields: location(there are more than 50
> locations) and age. I am having difficulty building clean rules for the
> following pseudo-code
>
>
> // Rule One
> if(location == "A") {
> if(age> 60)
> do_something();
> }
> // Rule Two
> else if(location == "B") {
> if(age> 70)
> do_something();
> }
> // Rule Three
> else if(location == "C") {
> if(age> 80)
> do_something();
> }
> // Rule Four
> else {
> if(age> 65)
> do_something();
> }
>
> The issue comes with Rule Four. How do I avoid writing the rule so that I
> don't have to say
(location!="A"&&location!="B"&&location!="C")
? I also
> don't want to have to write an explicit rule for every possible location.
>
> I considered an activation-group with salience to have the rules executed
> in order, but the problem is that if rules 1-3 do not fire, then rule 4
> fires for all locations - I can get a hit if location=="C" and age==70.
>
> Is it possible to have a 'Map' and do something like
> (age>map.get(location)) ? I could live with creating a map with all
> possible locations for key, although I'd rather not go this route.
>
> This problem is typical for the types of rules I'll be writing ... there
> can be completely different sets of rule criteria depending on location.
>
>
> Thanks in advance for your suggestions and your patience.
>
> _______________________________________________
> rules-users mailing list
> rules-users@.jboss
> https://lists.jboss.org/mailman/listinfo/rules-users
>
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_______________________________________________
rules-users mailing list
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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
1:26 p.m.
Hi,
you might try something like one of the following two variants:
a) Checking for Location only first, inserting a Fact for the respective
location and doing a second rule for each location that checks for this fact
and the age (using salience to ensure only one rule fires and this in the
correct order).
In this case, exactly one of the rules without the additional facts will
fire:
- if it is one of the first three, it will fire first, then after that the
rule with the additional fact will fire and give the correct result
- else, your "else" rule fires right away.
b) using different agenda-groups for the different locations and setting
focus to the location-specific agenda-group in a first step. If I get it
correctly (I am a newbie too and don't have the time to try it out), this
should work.
True, you have two rules for each location, but I find this acceptable:
- Rules should be simple and (close to) declarative
- If I read your requirements correctly, you typically filter on location,
so in the long run, there will be location-specific agenda-groups anyway if
you build a complete rule base.
Variant B could look like this:
rule "Rule One"
activation-group "CheckLocation"
salience 300
when
Person(location == "A" )
Then
drools.setFocus("Location-A");
end
rule "Location A: age>60"
agenda-group 'Location-A'
when
Person(age>60)
then
do_something();
end
rule "Rule Two"
activation-group "CheckLocation"
salience 200
when
Person(location == "B" )
Then
drools.setFocus("Location-B");
end
rule "Location B: age>70"
agenda-group "Location-B"
when
Person(age>70)
then
do_something();
end
rule "Rule Three"
activation-group "CheckLocation"
salience 100
when
Person(location == "C" )
Then
drools.setFocus("Location-C");
end
rule "Location C: age>80"
agenda-group "Location-C"
when
Person(age>80)
then
do_something();
end
rule 'Rule Else'
activation-group "CheckLocation"
salience 0
when
Person (age > 65 )
Then
do_something();
end
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4561
days inactive
4561
days old
4 comments
5 participants
participants (5)
-
Andreas Schlüter -
FrankVhh -
Ronald Albury -
Vincent Legendre -
Welsh, Armand