Salience
by huionn
If I have a rule like below:
rule "#1"
when
$i : Item(type == 1)
then
retract ($i)
// do something...
end
rule "#2"
when
$i : Item(type == 2)
then
retract ($i)
// do something...
end
// to handle other type of Item
rule "#catch-all"
salience -10
when
$i : Item()
then
retract ($i)
// do something...
end
As it is known, reliance on salience is bad practice and its order is not
guaranteed (as shown in Sudoku example).
My question is: what is the simple and good practice to emulate "else" (rule
"#catch-all") without reliance on salience? It seems ruleflow is not
applicable here as well.
Thanks and best regards.
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15 years, 5 months
Need clarification in dslr conversion
by Bala
Hi,
Please find the below sample dsl and dslr, in which only the keyword part is
alone getting converted in dslr. condition scope is not getting converted
when i look at the generated drl file. But when i change the scope from
condition to keyword, its getting converted.. am i missing something...
eg: [condition][]Get a Customer=$Customer : CustomerInfoType() is not
getting converted..
sample DSL
**********
[keyword][][Ii][fF]=when
[keyword][]Start Rule {ruleName}=rule {ruleName}
[keyword][]Template Header=template header
[keyword][]Start Template : "{tamplateName}"=template "{tamplateName}"
[keyword][]Finish Template=end template
[keyword][]FieldName {field}={field}
[keyword][]Start template Rule"{ruleName}"=rule
"{ruleName}__(a){row.rowNumber}"
[keyword][]Finish Rule=end
[keyword][][Aa]dd [Rr]ule [Ii]nfo :
{attribute}("{value}")=@{attribute}("{value}")
[condition][]1st=1
[condition][]2nd=2
[condition][]3rd=3
[condition][]Get a Customer=$Customer : CustomerInfoType()
[condition][]-with {fieldName} as {value}=${fieldName} : {fieldName},
{fieldName}=={value}
sample dslr
**********
expander pricingRules.dsl
Start Rule "AutoRatingDemo"
Add Rule Info : subRuleName("test")
Add Rule Info : author("Vishal Kaushik")
Add Rule Info : DateOfCreation("19-Jan-2011")
when
Get a Customer
-with customerCode as "23470942810"
then
end
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15 years, 5 months
Doubts in Using RulesBase object
by Nikhil S. Kulkarni
Hi All,
I am using JBOSS Rules 5.0.0, in which I am creating multiple RuleBase object based on package passed to it.
e.g.
public RuleBase (Package pkg)
{
RuleBase rb = RuleBaseFactory.newRuleBase();
rb.addPackage(pkg);
return rb;
}
Though I know that creating RuleBase object every time will have huge performance impact but it is required because when Multiple requests will
Come on the application server based on functionality that need to be triggered based on click of different buttons which internally call Rules.
So I am trying another option by declaring RuleBase as Static Object so that it will be shared across application, but I am facing two issues in that
Suppose I am using single RuleBase object then all the packages will be there that will be added using the above method on click of buttons which internally
Call rules by multiple users.
1) Now my problem is I cannot remove package after finish of my task as user because if Suppose two users A and B are performing the same task using different
Login. Now as User A, if he removes the package after its processing of rules completed then User B will not find that package for doing its task because if they both pass the above method at same time then both fill find package present in RuleBase.
2) If I keep all the packages as it is in RuleBase then Rules Engine will be triggered for all Rules present in all packages satisfying when condition.
So I am not able to understand what I exactly should do because currently I am facing performance issues in application and I think the Reason
is multiple RuleBase objects.
I have to change this So can anyone suggest me what I should do ??
Waiting for Reply.
Thanks & Regards,
Nikhil S. Kulkarni
MASTEK LTD.
In the US, we're called MAJESCOMASTEK
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15 years, 5 months
Greater than or less than in eval
by Mohod, Akash
Hi,
I am trying to write the following rule using Drools 5.1 but having issues.
when
Employee ($name : name, $ age : age)
Event ($eventName : eventName , $ageLimit : ageLimit)
eval($age < $ ageLimit)
then
System.out.println (" Can participate in the event ");
end
The rule fails to compile.
Regards,
Akash
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15 years, 5 months
Is there any way to find out last two events with some common properties
by umesh kumar sain
Is there any way to find out last two events with some common properties. In
my app I'd defined a pojo as drools event whose expiry time is say 5 mins.
Now I want to access the properties of last two events.
say something like this
rule "Props"
when
$E1 : MyEvent(prop1 = "MyProp") from entry-point MyStream
$E2 : MyEvent(prop1 = "MyProp", this != $E1) from entry-point MyStream
then
Do something
end
In the above rule my concern is that since the expiry time is 5 minutes and
I can receive any no of events during this period. How can I be sure that
the above two events $E1 and $E2 are the latest one i.e. last two events
received. I also thought of using sliding window but I don't know when they
are going to be received say 1s, 1m, or 5m.
kindly suggest
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15 years, 5 months
Trying to get Eclipse Java code to call Guvnor
by John Peterson
I'm using the example code from the Red Hat Magazine -
http://magazine.redhat.com/2008/08/12/jboss-drools-how-to-tuning-guvnor-
part-1/ - to try to get the sample code to work, but I keep getting the
following error:
Exception in thread "main" java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Unknown Source)
at java.util.Properties.load0(Unknown Source)
at java.util.Properties.load(Unknown Source)
at
org.drools.agent.RuleAgent.loadFromProperties(RuleAgent.java:299)
at org.drools.agent.RuleAgent.newRuleAgent(RuleAgent.java:256)
at test.GuvnorTest.main(GuvnorTest.java:15)
It appears to be unable to find my 'Guvnor.properties' file, but I have
it in the classpath (I actually have it in several different places on
my C: drive as I tried to figure out why it couldn't find it). Does
anyone have any thoughts on what's wrong here?
I'd appreciate any guidance. It seems like this should be a simple
answer but I haven't been able to figure it out.
15 years, 5 months
Sudoku example doesn't work in drools 5.1
by cafebabe
With reference to issue https://issues.jboss.org/browse/JBRULES-2867 and
thread "Bug in Sudoku Example - with fix"
http://drools-java-rules-engine.46999.n3.nabble.com/Bug-in-Sudoku-Example...,
sudoku example in Drools 5.1 is not working correctly.
drools version: 5.1.1
Although the fix in "Bug in Sudoku Example - with fix" (not
(PossibleCellValue( row == $row, value == $value ) || ResolvedCellValue( row
== $row, value == $value) ) ) can fix the problem, I don't understand why
rule #6, rule #7 and rule #8 are fired before rule #3, rule #4 and rule #5
even through rules #3, #4 and #5 have higher salience. If rules #3, #4 and
#5 have been fired first as expected, then PossibleCellValue with same value
as ResolvedCellValue should have been retracted (so there is no need to
check against ResolvedCellValue in rules #6, #7 and #8)
Does it mean that salience will not be always followed strictly during
runtime? Or it is an issue to be fixed in 5.2?
I understand that dependence on salience is discouraged, however without it,
extra condition is required.
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15 years, 5 months
KnowledgeAgent doesn't throw an exception even if it is not able to get the resource
by Harshit Bapna
Hello All,
I am using knowledgeAgent to retrieve a resource from Guvnor.
I have deliberately stopped the Guvnor to check if it throws any error but
KnowledgeAgent eats up the error.
*How can it be detected that an error occurred during creation of
knowledgeBase?*
*ConsoleOutput:*
Although KnowledgeAgent does logging in console
[2011:01:18 21:01:916:exception]
java.lang.RuntimeException: KnowledgeAgent exception while trying to
deserialize KnowledgeDefinitionsPackage
at
org.drools.agent.impl.KnowledgeAgentImpl.createPackageFromResource(KnowledgeAgentImpl.java:664)
at
org.drools.agent.impl.KnowledgeAgentImpl.addResourcesToKnowledgeBase(KnowledgeAgentImpl.java:889)
at
org.drools.agent.impl.KnowledgeAgentImpl.rebuildResources(KnowledgeAgentImpl.java:704)
...
*Caused by: java.net.UnknownHostException: <hostName>*
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:177)
at java.net.Socket.connect(Socket.java:520)
at java.net.Socket.connect(Socket.java:470)
at sun.net.NetworkClient.doConnect(NetworkClient.java:157)
15 years, 5 months
loading rules into one package
by Piotr Jedrychowski
Hello.
I'm loading a lot of rules during starting of JBoss. Loading of rules is
made by such scenario:
1) Read first part of rules from database (about 4000 rules)
2) Send rules to Drools bean
3) Parse rules (convert string rules into Drools format) by
KnowledgeBuilder - one package (pkg1) with all rules
4) Add rules into KnowledgeBase
5) Read second part of rules from database (about 4000)
6) Send rules to Drools bean
7) Parse rules (convert string rules into Drools format) by
KnowledgeBuilder - one package (pkg1 - the same ad in point 3)) with all
rules
8)Add rules into KnowledgeBase
and during second add operation JVM turns off, and generates file:
hs_err_pid<number>.log with this log:
C2:101% !
org.drools.lang.DRLParser.rhs_chunk_data()Lorg/drools/lang/DRLParser$rhs_chunk_data_return;
@ 169 (723 bytes)
What is the reason of this behaviour? Is it possible to add rules to
existing packaged - 8) point from scenario? Maybe someone had similar
problem?
I'm using:
1) Drools 5.1.0
2) JBoss 4.2.3
Regards,
Piotr
15 years, 5 months
