DROOLS having RHS dynamic(5.0)
by shikha.x.aggarwal＠jpmchase.com
Hi,
I am looking to use drools where I can have users subscribed to specific
alerts. Hence for example -
I can have a rule like ->
Rule 1 -> amount < {amount}
Where {amount} is the value which the user defines at the time of
subscribing, hence the user wants to recieve an alert when the amount in
his account < {amount} that he just subscribed to.
I was trying to use the DROOLS template feature and was even able to
succesfully execute this specific scenario. The use case I was executing
is, when an event of type Rule 1 occurs , I get all users who are
subscribed to rule 1, and then create a drl file for all of those users
with there custom data substituted as part of {amount}. Now I fire the
rules(note I have multiple rules one for each user} which executes for
this specific event and gives the required results(The above example is
just a sample example). My area of concerns are -
1. Is Rule engine really the platform I am looking at? As I dont have any
complex logic , I just want to use some component which can evaluate my
Events that arrive with different subscription rules?
2. If I regenearte the drl file every time an event arrives (I need to
because every time a iff type of rule can fire and the list of subscribers
can be different as well), this would have a performace impact as the
rules are compiled and generated every time and not really cached?
Please let me know if the problem is not clear. Any help/inputs in this
regard would be highly appreciated.
Thanks
Shikha
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16 years, 1 month
Rules Scoring
by Waleed Zedan
Hi,
We are in the process of evaluating JBOSS Drools for our software and so far
Drools found to be a perfect match for most of our requirements.
Recently our customer has requested for a very interesting and important
requirement and its synopysis is given below
Rule
LHS
Condition 1 / Condition Group 1 (assoicated weightage is 20)
Condition 2 / Condition Group 2 (assoicated weightage is 50)
Condition 3 / Condition Group 3 (assoicated weightage is 30)
RHS
Rule Action / Output
While calling the Rule Engine, the Rule Engine client will say "Give me all
the Rule Output for the Rules matching 50% of the LHS"
i.e. We need to know the percentage of LHS match in the RHS
Using this percentage, we will call the Rule Action / Output
Sample:
if Condition 2 / Condition Group 2 and Condition 1 / Condition Group 1 are
satisfied, then we need to have 70% (50% + 20%) match in the RHS.
Thanks a lot for your help and time.
--
Waleed Zedan
SCJP 1.4 , CCNA
16 years, 1 month
Nested Rules
by Vishal Deshmukh
Hi
I am using Drools 4.0.4 with Eclipse 3.2. I m much happy with the results. But now my application needs nested loops..
Can i write nested rules like
rule "rule 1 " // if condition of rule 1 is true then only execute rule 2 other wise skip it
when
condition is true
then
execute rule2
rule "rule 2 "
when
condition is true
then
action
rule "rule 3"
when
condition is true
then
action
Thanks and Rgards
Vishal
16 years, 1 month
Chart notation, update, and infinite loops
by Dan Seaver
I'm trying to find a good technique for updating specific facts in working
memory. What I'm currently doing is something like this:
Rule "Update Amount"
when
amountFact : Fact(name == "Amount")
charge : Charge()
then
Double amount = amountFact.getAmount();
Double chargeAmount = charge.getAmount();
amountFact.setAmount(amount + chargeAmount);
update(amountFact);
end
The update statement causes an infinite loop.
I tried using no-loop, which works if there is 1 charge, but not if there
are more than one.
Any help with solutions or strategies would be much appreciated.
--
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16 years, 1 month
Serialization in Drools 5.0 M2
by siddhartha banik
Hi Drools Team,
I am trying out new Serialization technique introduced in Drools 5.0 using "
org.drools.marshalling.DefaultMarshaller".
The use case I am trying, is:
Create a Stateful session.
Then Serialize that.
Try to load the the serialized session
back.
Loading of serialized session is working good if, I try that in same java
program & same object of DefaultMarshaller is used during serialization & de
serialization of the Stateful session.
But, when I tried a different instance of DefaultMarshaller to read back the
saved session, that is not working anymore. I am getting a exception :
java.lang.NullPointerException
at org.drools.common.DefaultFactHandle.<init>(DefaultFactHandle.java:78)
at
org.drools.marshalling.InputMarshaller.readFactHandle(InputMarshaller.java:331)
at
org.drools.marshalling.InputMarshaller.readFactHandles(InputMarshaller.java:277)
at
org.drools.marshalling.InputMarshaller.readSession(InputMarshaller.java:179)
at org.drools.marshalling.DefaultMarshaller.read(DefaultMarshaller.java:58)
at org.drools.marshalling.DefaultMarshaller.read(DefaultMarshaller.java:15)
at
org.drools.reteoo.ReteooRuleBase.readStatefulSession(ReteooRuleBase.java:277)
at
org.drools.common.AbstractRuleBase.readStatefulSession(AbstractRuleBase.java:321)
at
com.sample.test.NewMarshallingTest.testSerializationInFile_1(NewMarshallingTest.java:79)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at
org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130)
at
org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at
org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
With Drools 4.0.7 ... I can serialize a Stateful session & at later point of
time I can deserialize that back. For our usecase, the feature is very
critical.
Does Drools 5.0 support that ? DefaultMarshaller is not serializable. So
once a Stateful session is serialized. At Later point of time, I am not
able to read that back.
I have attached my test files.
Best Regards!
Siddhartha
16 years, 1 month
can we mix java n mvel dialect in LHS
by techy
Hello,
I have some drools beginner questions
1.what is default dialect if it is not specified?
2. can We mix java and mvel syntax in LHS?
Ex:
class Cheese(String type,Set<String> ingredients)
Is this valid LHS?
when cheese : Cheese(ingredients.getIngredients().size > 3,type ==
"American")
3. In my sample program , I have a following condition which never executes
even if i have "sugar" ingredient. any help?
when cheese : Cheese(ingredients contains "sugar")
--
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16 years, 1 month
Complex rule
by Bryan Hansen
Not really sure how to go about writing this in a rule or whether or not the
logic belongs in a rule (I think it does, but if you don't please comment as
to why).
I have a list of objects that contain date objects. If the list contains 10
objects that date are before mine then I want them to take a break.
The business case is similar to that of an HR system. If they have worked
too many days out of the last 12 then they need to take a break.
I am guessing it would have to use the "collect" attribute, but how would
you do the date logic in a LHS clause?
Thanks for any guidance on this.
16 years, 1 month
Newbie question on accessing predecessor and successor in a list
by CSchr
Hi everyone!
I'm relatively new to Drools and rule languages.
I'm wondering if it is possible to access the predecessor and successor in a
match using from operator on an (Array)List. I have something like this
(simplified):
...
$segment : Segment( countries contains Country.Switzerland && ... ) from
$journey.segmentList
$preSegment : Segment ( indexOf(this) == indexOf($segment) - 1,
countries not contains Country.Switzerland && ...
) from $journey.segmentList
I need something like indexOf() for the exact predecessor of the matched
segment.
If the matched business object was an element of a double linked list it
would be easy. Unfortunately I don't have the luxury to change the business
object into knowing it's predecessor or successor. I have to prove that we
could write our java coded business rules in Drools rule language without
changing the business object model.
Thanks in advance,
Chris
--
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16 years, 1 month
