Fire Rule in Stateless Knowledge Session
by snehils
Hi,
I am new in Drools. I am using Drools version 5.1.0
My requirement is kind of request response, where I have to perform some
checks for the request and respond the result. Hence, I decided to go with
stateless knowledge session.
I have prepared .DRL file and it contains set of rules. When some request
receives I have to identify the rule(s) belongs to that request and then
fire the rule(s).
I am not able to figure out how to categories the rules request wise in DRL
file? Also, how to fire only those rules which belongs to the category.
For example, there are three kinds of requests Rq1, Rq2 and Rq3. There are
rules in DRL file: R1, R2, R3, R4 and R5. R1, R2 belongs to Rq1, R3 belongs
to Rq2 and R4, R5 belongs to Rq3.
When some request receives only its belonging rules should be fired. For
example, on receiving of Rq2 only R3 should be fired.
Please provide me some code snipped or link.
Thanks
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10 years, 10 months
Guvnor: Accessing Bound Variable in "Then" Statement
by Vann_the_Red
Hello. I started with a search and didn't find an answer. I apologize if my
search-fu was lacking today.
I'm a non-developer tasked with rules creation and testing using guvnor. I
have found some scenarios where I can bind a variable to either the whole
input model or a fact in the input model and then later access those in the
output model by selecting "Bound Variable" from the popup box in the Then
statement. In other scenarios, "Bound Variable" is not an option (only
Literal or Formula). What must I do to be able to access the bound
variables from the When statement(s) in the Then statement(s)?
TIA,
Vann
This is a repost because I wasn't on the mailing list yet and I gather most
didn't see it. Apologies again.
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10 years, 10 months
How to write Hibernate query lang(HQL) in .DRL file
by zeeshan
Hi !
According to my requirement I need to fetch and Insert data from database
using Hibernate Query from .DRL file.
I have idea how to execute HQL in Plain Java class but according to my
requirement,I need to fire query to database from .DRL file which I tried
but unable to get output instead I was getting errors.
Can anyone suggest me process to execute Hibernate Query from DRL file
or please provide me some sample code or any link.
Thanks !!
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10 years, 11 months
[Drools Planner] Multi depot CVRP / CVRPTW
by Mats Norén
Hi,
I've been looking at the VRP example in Drools and I'm thinking about using
it for multi depot cvrp and / or capacitated vrp with time windows.
Has anyone else tried planner for these use cases and can maybe shed some
light on their implementation?
Regards,
Mats
11 years
"Rule-Id" for a Drools Rule
by harishtejwani
All:
We are using Drools to detect specific events/conditions in our system.
In the 'then' condition of Drools rule, we would like to persist the "Rule
Id" of the rule that created the specific event/condition
This is because all our reporting is based on "rules" as filters, where
users can look at exceptions by specific rules.
Is there a suggestion or sample as how can the "Rule Id" be persisted or
indicated in the then condition that is immutable or can be long-lived. The
current approach of using Rule Name itself as the ID is brittle as this can
be changed and suddenly all reports would break.
If we assign ID's to rules, where do we keep the mapping of RULE ID to
Rules. If we store rules in GUVRNOR is there a way we can get Rule Id's for
Rules?
Best regards
Harish Tejwani
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11 years
Question about drools-spring in a multi-treaded container (like tomcat).
by Gurvinder Narula1
Hello all,
I've been reading up about drool-spring integration and have put together a simple project that wires together a KnowledgeBase and KnowledgeSession as follows :
<drools:resource id="GroupUnit" type="DRL"
source="file:/Users/drools/drools-spring-test/src/Rules/drls/GroupUnit.drl" />
<drools:resource id="GradeUnit" type="DRL"
source="file:/Users/drools/drools-spring-test/src/Rules/drls/GradeUnit.drl"" />
<drools:resource id="EvaluateUnit" type="DRL"
source="file:/Users/drools/drools-spring-test/src/Rules/drls/EvaluateUnit.drl"" />
<drools:grid-node id="node1" />
<drools:kbase id="kbase1" node="node1">
<drools:resources>
<drools:resource ref="GroupUnit" />
<drools:resource ref="GradeUnit" />
<drools:resource ref="EvaluateUnit" />
</drools:resources>
</drools:kbase>
<drools:ksession id="ksession" type="stateful" kbase="kbase1"
node="node1" />
Then in my Controller call, I 'AutoWire' in the StatefulKnowledgeSession as follows :
@Controller
@RequestMapping( value = "foo" )
final class FooController{
@Autowired
StatefulKnowledgeSession ksession;
@RequestMapping( method = RequestMethod.GET )
@ResponseBody
public String evaluateUnit() {
Unit unit = new Unit("030", "502", "C", "9484", "45", new String[] {},
null);
if (ksession != null) {
ksession.fireAllRules();
ksession.insert(unit);
ksession.fireAllRules();
return "<UnitCategory>" + unit.getUnitCategory() + "</UnitCategory>";
}
else
return "<message> stateful session is null</message>";
}
The main question that I have is that – is this solution thread-safe ? From what I understand of spring is that beans configured without any additional qualifiers are inherently singletons. And when deployed in a multi-theaded container like tomcat, Spring assumes that the beans being severed up a thread-safe. So from I have read is that KnowledeSessions are inherently not thread safe. So putting the 2 together, I leaning towards the assessment that this above solution is NOT thread safe and that if I do want it to be thread safe I should set the StatefulKnowledgeSession to 'prototype' and not leave it as a singleton.
Please let me know if I'm missing anything in my assessment here !
Thanks in advance,
Gurvinder
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11 years, 1 month
