Drools

https://kie.apache.org/docs/10.1.x/drools/
Admin
Drools is a set of projects for intelligent automation and decision management, providing a...
Tokens:110,102
Snippets:1,432
Trust Score:10
Update:3 months ago
Show doc for...
Tokens:
Raw
### Build and Install Maven Project

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Standard Maven command to build and install the project, making KieBases and KieSessions available on the classpath.

```bash
mvn install
```

--------------------------------

### Example ReteDumper Output

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example output from ReteDumper, showing the mapping between Rete nodes and rule names.

```text
[ AccumulateNode(8) ] : [Collect expensive orders combination]
...
```

--------------------------------

### Person Fact Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Illustrates the creation of Person objects used in fact equality mode examples.

```java
Person p1 = new Person("John", 45);
Person p2 = new Person("John", 45);
```

--------------------------------

### Build and Install KieModule JAR - Maven

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Use this Maven command to build and install a KieModule JAR into the local repository. This is a prerequisite for referencing the JAR as a file resource in subsequent steps.

```bash
mvn install
Copied!

```

--------------------------------

### Register and Start KieScanner

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Register and start a KieScanner on a KieContainer to poll the Maven repository at a specified interval. Requires kie-ci.jar on the classpath.

```java
KieServices kieServices = KieServices.Factory.get();
ReleaseId releaseId = kieServices.newReleaseId( "org.acme", "myartifact", "1.0-SNAPSHOT" );
KieContainer kContainer = kieServices.newKieContainer( releaseId );
KieScanner kScanner = kieServices.newKieScanner( kContainer );

// Start the KieScanner polling the Maven repository every 10 seconds
kScanner.start( 10000L );
```

--------------------------------

### Example SingletonStore Usage

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Shows how to set, update, and clear a single element in a SingletonStore. This is similar to a global but reactive to changes.

```java
SingletonStore<Measurement> measurement = DataSource.createSingleton();
Measurement m1 = new Measurement("color", "red");
// Add value `m1` and notify all subscribers
measurement.set(m1);
measure.setValue("blue");
// Notify all subscribers that the value has changed
measurement.update();

Measurement m2 = new Measurement("color", "green");
// Overwrite contained value with `m2` and notify all subscribers
measurement.set(m2);
measure2.setValue("black");
// Notify all subscribers that the value has changed
measurement.update();

// Clear store and notify all subscribers
measurement.clear();
```

--------------------------------

### Register and Start KIE Scanner

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Register and start a KIE scanner for a KIE container, configured to poll the Maven repository at a specified interval. Ensure the 'kie-ci.jar' is on the classpath. The project version must be a SNAPSHOT version for the scanner to detect updates.

```java
import org.kie.api.KieServices;
import org.kie.api.builder.ReleaseId;
import org.kie.api.runtime.KieContainer;
import org.kie.api.builder.KieScanner;

...

KieServices kieServices = KieServices.Factory.get();
ReleaseId releaseId = kieServices
  .newReleaseId("com.sample", "my-app", "1.0-SNAPSHOT");
KieContainer kContainer = kieServices.newKieContainer(releaseId);
KieScanner kScanner = kieServices.newKieScanner(kContainer);

// Start KIE scanner for polling the Maven repository every 10 seconds (10000 ms)
kScanner.start(10000L);

```

--------------------------------

### Maven Profile Activation in settings.xml

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Example of a Maven profile configuration within settings.xml, demonstrating how to activate a profile by default.

```xml
<profiles>
  <profile>
    <id>profile-1</id>
    <activation>
      <activeByDefault>true</activeByDefault>
    </activation>
    ...
  </profile>
</profiles>
```

--------------------------------

### Maven Archetype Interactive Input Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/getting-started/index.html

Example of interactive property value inputs during the `mvn archetype:generate` command execution for project configuration.

```shell
Define value for property 'groupId': org.example
Define value for property 'artifactId': my-project
Define value for property 'version' 1.0-SNAPSHOT: :
Define value for property 'package' org.example: :
... Y: : Y
...
[INFO] BUILD SUCCESS
Copied!
```

--------------------------------

### Example DataStore Usage

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Illustrates adding, updating, and removing data from a DataStore. DataStore is a writable storage equivalent to a typed entry point.

```java
DataStore<Measurement> measurements = DataSource.createStore();
Measurement measurement = new Measurement("color", "red");
// Add value and notify all subscribers
DataHandle mHandle = measurements.add(measurement);
measure.setValue("blue");
// Notify all subscribers that the value referenced by `mHandle` has changed
measurements.update(mHandle, measurement);
// Remove value referenced by `mHandle` and notify all subscribers
measurements.remove(mHandle);
```

--------------------------------

### DRL Example: Logically Insert New Applicant

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example rule action to logically insert a new `Applicant` object into the working memory.

```java
insertLogical( new Applicant() );
```

--------------------------------

### DRL 'forall' Condition Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Provides an example of the 'forall' construct used to verify if all facts matching the first pattern also match the remaining patterns. Variables bound within 'forall' are not available outside its scope.

```java
rule "All full-time employees have red ID badges"
  when
    forall( $emp : /employees[ type == "fulltime" ]
                   /employees[ this == $emp, badgeColor == "red" ] )
  then
    // True, all full-time employees have red ID badges.
end
```

--------------------------------

### Drools Decision Table: Import and Functions Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Provides an example of how to specify imports and define functions within a decision table. Functions must be written as they appear in a DRL file.

```java
import com.sample.Cheese
import com.sample.Person
```

```java
function int computePrice(Cheese cheese) {
    if (cheese.getType() == "cheddar") {
        return 10;
    } else if (cheese.getType() == "stilton") {
        return 15;
    } else {
        return 20;
    }
}

function boolean hasDiscount(Person person) {
    if (person.getAge() > 60) {
        return true;
    } else {
        return false;
    }
}
```

--------------------------------

### DRL Example: Update Loan Application

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example rule action to update a loan application amount and approval status using the `update` method.

```java
$application.setAmount( 100 );
update( $application );
```

--------------------------------

### Maven Build with Tests

Source: https://kie.apache.org/docs/10.1.x/drools/drools/introduction/index.html

Execute a full Maven build including all tests. Ensure Java JDK 17+ and Maven 3.9.6+ are installed.

```bash
mvn clean install
```

--------------------------------

### FEEL String Literal Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/DMN/index.html

Demonstrates the syntax for string literals in FEEL, which are enclosed in double quotation marks.

```feel
"John Doe"
```

--------------------------------

### Example DataStream Usage

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Demonstrates creating and appending data to a DataStream. DataStream is an append-only storage suitable for publishing data.

```java
DataStream<Measurement> measurements = DataSource.createStream();
// Append value and notify all subscribers
measurements.append(new Measurement("color", "red"));
```

--------------------------------

### Separating Constraint Bindings and Expressions

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Advises separating constraint bindings from constraint expressions for clarity and efficiency, providing an example of the recommended format.

```java
// Do not use the following format:
/persons[ age : age * 2 < 100 ]

// Use the following format instead:
/persons[ age * 2 < 100, $age : age ]
```

--------------------------------

### Declare Open-Ended Maven Version Range

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Declares an open-ended version range for a Maven dependency, starting from '1.0.0'. This will resolve to the latest available version, '2.0.0' in this example.

```xml
<version>[1.0.0,)</version>
```

--------------------------------

### Utilize KieSession with Multiple KieBases

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Java code to test a KieSession configured in kmodule.xml. This example demonstrates how to retrieve a KieSession by name and execute rules.

```java
@Test
public void testSimpleKieBase() {
    List<Integer> list = useKieSession("ksession1");
    // no packages imported means import everything
    assertEquals(4, list.size());
    assertTrue( list.containsAll( asList(0, 1, 2, 3) ) );
}

//.. other tests for ksession2 to ksession6 here

private List<Integer> useKieSession(String name) {
    KieServices ks = KieServices.Factory.get();
    KieContainer kContainer = ks.getKieClasspathContainer();
    KieSession kSession = kContainer.newKieSession(name);

    List<Integer> list = new ArrayList<Integer>();
    kSession.setGlobal("list", list);
    kSession.insert(1);
    kSession.fireAllRules();

    return list;
}
```

--------------------------------

### EventA started by EventB

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Use this pattern to match if EventA and EventB start at the same time, and EventB ends before EventA ends. This is the reverse behavior of the 'starts' operator.

```java
$eventA : EventA(this startedby $eventB)
```

```java
$eventA.startTimestamp == $eventB.startTimestamp
&&
$eventA.endTimestamp > $eventB.endTimestamp
```

--------------------------------

### EventA started by EventB within 5 seconds

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Use this pattern to match if EventA starts within 5 seconds of EventB starting, and EventA ends after EventB ends. Ensure non-negative intervals are used.

```java
$eventA : EventA( this starts[5s] $eventB)
```

```java
abs( $eventA.startTimestamp - $eventB.startTimestamp ) <= 5s
&&
$eventA.endTimestamp > $eventB.endTimestamp
```

--------------------------------

### EventA starts EventB within 5 seconds

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Use this pattern to match if EventA starts within 5 seconds of EventB starting, and EventA ends before EventB ends. Ensure non-negative intervals are used.

```java
$eventA : EventA(this starts[5s] $eventB)
```

```java
abs($eventA.startTimestamp - $eventB.startTimestamp) <= 5s
&&
$eventA.endTimestamp < $eventB.endTimestamp
```

--------------------------------

### Configure KieBase and KieSession in kmodule.xml

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

This kmodule.xml example demonstrates defining two KieBases with different configurations and multiple KieSessions, including stateful and stateless types, custom operators, and logging.

```xml
<kmodule xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns="http://www.drools.org/xsd/kmodule">
  <configuration>
    <property key="drools.evaluator.supersetOf" value="org.mycompany.SupersetOfEvaluatorDefinition"/>
  </configuration>
  <kbase name="KBase1" default="true" eventProcessingMode="cloud" equalsBehavior="equality" declarativeAgenda="enabled" packages="org.domain.pkg1">
    <ksession name="KSession2_1" type="stateful" default="true"/>
    <ksession name="KSession2_2" type="stateless" default="false" beliefSystem="jtms"/>
  </kbase>
  <kbase name="KBase2" default="false" eventProcessingMode="stream" equalsBehavior="equality" declarativeAgenda="enabled" packages="org.domain.pkg2, org.domain.pkg3" includes="KBase1">
    <ksession name="KSession3_1" type="stateful" default="false" clockType="realtime">
      <fileLogger file="drools.log" threaded="true" interval="10"/>
      <workItemHandlers>
        <workItemHandler name="name" type="org.domain.WorkItemHandler"/>
      </workItemHandlers>
      <calendars>
        <calendar name="monday" type="org.domain.Monday"/>
      </calendars>
      <listeners>
        <ruleRuntimeEventListener type="org.domain.RuleRuntimeListener"/>
        <agendaEventListener type="org.domain.FirstAgendaListener"/>
        <agendaEventListener type="org.domain.SecondAgendaListener"/>
        <processEventListener type="org.domain.ProcessListener"/>
      </listeners>
    </ksession>
  </kbase>
</kmodule>
```

--------------------------------

### DRL Example: Delete Applicant

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example rule action to delete an `Applicant` object from the working memory.

```java
delete( Applicant );
```

--------------------------------

### FEEL Date and Time Construction Examples

Source: https://kie.apache.org/docs/10.1.x/drools/drools/DMN/index.html

Demonstrates constructing date and time values using the `date and time()` function. Supports XML Schema Part 2 format with optional timezone offsets.

```feel
date and time( "2017-10-22T23:59:00" )
```

```feel
date and time( "2017-06-13T14:10:00+02:00" )
```

```feel
date and time( "2017-02-05T22:35:40.345-05:00" )
```

```feel
date and time( "2017-06-13T15:00:30z" )
```

--------------------------------

### FEEL Date Construction Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/DMN/index.html

Shows how to construct date values using the built-in `date()` function in FEEL. Date strings must follow the 'YYYY-MM-DD' format.

```feel
date( "2017-06-23" )
```

--------------------------------

### FEEL Time Construction Examples

Source: https://kie.apache.org/docs/10.1.x/drools/drools/DMN/index.html

Illustrates the construction of time values using the `time()` function in FEEL. Supports various formats including timezone offsets and UTC.

```feel
time( "04:25:12" )
```

```feel
time( "14:10:00+02:00" )
```

```feel
time( "22:35:40.345-05:00" )
```

```feel
time( "15:00:30z" )
```

--------------------------------

### DRL Example: Insert New Applicant

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example rule action to insert a new `Applicant` object into the working memory.

```java
insert( new Applicant() );
```

--------------------------------

### Build KieModule with Impact Analysis

Source: https://kie.apache.org/docs/10.1.x/drools/drools/experimental-features/index.html

Set up KieFileSystem and build all assets, passing ImpactAnalysisProject.class to enable impact analysis.

```java
// set up KieFileSystem
      ...
      KieBuilder kieBuilder = KieServices.Factory.get().newKieBuilder(kfs).buildAll(ImpactAnalysisProject.class);
      ImpactAnalysisKieModule analysisKieModule = (ImpactAnalysisKieModule) kieBuilder.getKieModule();
      AnalysisModel analysisModel = analysisKieModule.getAnalysisModel();
```

--------------------------------

### Instantiate Stateful KIE Session and Insert Initial Data

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Creates a KieSession, inserts Room and Sprinkler facts, and fires all rules. This initial state should result in 'Everything is ok'.

```java
KieSession ksession = kContainer.newKieSession();

String[] names = new String[]{"kitchen", "bedroom", "office", "livingroom"};
Map<String,Room> name2room = new HashMap<String,Room>();
for( String name: names ){
    Room room = new Room( name );
    name2room.put( name, room );
    ksession.insert( room );
    Sprinkler sprinkler = new Sprinkler( room );
    ksession.insert( sprinkler );
}

ksession.fireAllRules();
```

--------------------------------

### BatchExecution Command with StatelessKieSession

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Illustrates executing a list of commands, including inserting objects, starting a process, and executing a query, in a single call using BatchExecution. Results with out identifiers are added to ExecutionResults.

```java
StatelessKieSession ksession = kbase.newStatelessKieSession();

List cmds = new ArrayList();
cmds.add( CommandFactory.newInsertObject( new Cheese( "stilton", 1), "stilton") );
cmds.add( CommandFactory.newStartProcess( "process cheeses" ) );
cmds.add( CommandFactory.newQuery( "cheeses" ) );
ExecutionResults bresults = ksession.execute( CommandFactory.newBatchExecution( cmds ) );
Cheese stilton = ( Cheese ) bresults.getValue( "stilton" );
QueryResults qresults = ( QueryResults ) bresults.getValue( "cheeses" );

```

--------------------------------

### DRL Example: Modify Loan Application

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example rule action to modify a loan application amount and approval status using the `modify` method.

```java
modify( $application ) {
        setAmount( 100 ),
        setApproved ( true )
}
```

--------------------------------

### Execute Rule Unit Instance in Java

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

This snippet shows how to instantiate a RuleUnit, add data, create a RuleUnitInstance, fire rules, and assert results. It also demonstrates clearing results and adding new data for subsequent rule firings.

```java
    public void helloWorld() {
        HelloWorldUnit unit = new HelloWorldUnit();
        unit.getStrings().add("Hello World");

        RuleUnitInstance<HelloWorldUnit> unitInstance = RuleUnitProvider.get().createRuleUnitInstance(unit);

        assertThat(unitInstance.fire()).isEqualTo(2);
        assertThat(unit.getResults()).containsExactlyInAnyOrder("it worked!", "it also worked with HELLO WORLD");

        unit.getResults().clear();
        unit.getInts().add(11);
        assertThat(unitInstance.fire()).isEqualTo(1);
        assertThat(unit.getResults()).containsExactly("String 'Hello World' is 11 characters long");

        unitInstance.close();
    }

```

--------------------------------

### Event Starts Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Matches if eventA and eventB start at the same time, and eventA ends before eventB ends. This can also be expressed using explicit timestamp comparisons.

```java
$eventA : EventA(this starts $eventB)
```

```java
$eventA.startTimestamp == $eventB.startTimestamp
&&
$eventA.endTimestamp < $eventB.endTimestamp
```

--------------------------------

### Insert Facts into Entry Point in Java

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

This Java code demonstrates how to obtain an EntryPoint object and insert facts into a specific stream like 'ATM Stream'. Rules referencing this entry point will then evaluate against these facts.

```java
import org.kie.api.runtime.KieSession;
import org.kie.api.runtime.rule.EntryPoint;

// Create your KIE base and KIE session as usual.
KieSession session = ...

// Create a reference to the entry point.
EntryPoint atmStream = session.getEntryPoint("ATM Stream");

// Start inserting your facts into the entry point.
atmStream.insert(aWithdrawRequest);
```

--------------------------------

### Example Drools Metric Log Output

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example of rule execution logs generated when drools-metric is configured for logging. Pay attention to evalCount and elapsedMicro for performance insights.

```log
TRACE [JoinNode(6) - [ClassObjectType class=com.sample.Order]], evalCount:1000, elapsedMicro:5962
TRACE [JoinNode(7) - [ClassObjectType class=com.sample.Order]], evalCount:100000, elapsedMicro:95553
TRACE [ AccumulateNode(8) ], evalCount:4999500, elapsedMicro:2172836
TRACE [EvalConditionNode(9)]: cond=com.sample.Rule_Collect_expensive_orders_combination930932360Eval1Invoker@ee2a6922], evalCount:49500, elapsedMicro:18787
```

--------------------------------

### Utilize and Run KieModule with Defaults - Java

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

This Java code snippet shows how to programmatically build, deploy, and run a KieModule using default configurations. It involves writing a rule file, building the module, and creating a KieSession.

```java
KieServices ks = KieServices.Factory.get();
KieRepository kr = ks.getRepository();
KieFileSystem kfs = ks.newKieFileSystem();

kfs.write("src/main/resources/org/kie/example5/HAL5.drl", getRule());

KieBuilder kb = ks.newKieBuilder(kfs);

kb.buildAll(); // kieModule is automatically deployed to KieRepository if successfully built.
if (kb.getResults().hasMessages(Level.ERROR)) {
    throw new RuntimeException("Build Errors:\n" + kb.getResults().toString());
}

KieContainer kContainer = ks.newKieContainer(kr.getDefaultReleaseId());

KieSession kSession = kContainer.newKieSession();
kSession.setGlobal("out", out);

kSession.insert(new Message("Dave", "Hello, HAL. Do you read me, HAL?"));
kSession.fireAllRules();
javaCopied!

```

--------------------------------

### VoiceCall fact class example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

This is a sample Java class representing a VoiceCall, used in Drools DRL examples. It includes fields for origin, destination, call time, and duration.

```java
public class VoiceCall {
  private String  originNumber;
  private String  destinationNumber;
  private Date    callDateTime;
  private long    callDuration;  // in milliseconds

  // Constructors, getters, and setters
}
```

--------------------------------

### FEEL Days and Time Duration Construction Examples

Source: https://kie.apache.org/docs/10.1.x/drools/drools/DMN/index.html

Shows how to construct days and time duration values using the `duration()` function. Supports ISO 8601 format restricted to days, hours, minutes, and seconds.

```feel
duration( "P1DT23H12M30S" )
```

```feel
duration( "P23D" )
```

```feel
duration( "PT12H" )
```

```feel
duration( "PT35M" )
```

--------------------------------

### DRL Rule Example (Traditional Syntax)

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

An example of a Drools Rule Language (DRL) rule using the traditional syntax, illustrating the same loan application age limit logic.

```drl
rule "Underage"
  when
    Applicant( applicantName : name, age < 21 )
    $application : LoanApplication( applicant == applicantName )
  then
    $application.setApproved( false );
    $application.setExplanation( "Underage" );
    update($application);
end
```

--------------------------------

### Create KIE Container from Classpath

Source: https://kie.apache.org/docs/10.1.x/drools/drools/DMN/index.html

Initializes a KIE container by loading knowledge assets directly from the Java classpath. This is suitable when KJARs are included as project dependencies or resources.

```java
KieServices kieServices = KieServices.Factory.get();

KieContainer kieContainer = kieServices.getKieClasspathContainer();
```

--------------------------------

### DRL Rule Example (New Syntax)

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

An example of a Drools Rule Language (DRL) rule using the new syntax, demonstrating conditions for a loan application's age limit.

```drl
rule "Underage"
  when
    /applicants[ applicantName : name, age < 21 ]
    $application : /loanApplications[ applicant == applicantName ]
  then
    $application.setApproved( false );
    $application.setExplanation( "Underage" );
    update($application);
end
```

--------------------------------

### Configure KIE Base

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Example configuration for a KIE base in a kmodule.xml file. This defines a repository for rules and can include package names and other KIE bases.

```xml
<kmodule>
  ...
  <kbase name="KBase2" default="false" eventProcessingMode="stream" equalsBehavior="equality" declarativeAgenda="enabled" packages="org.domain.pkg2, org.domain.pkg3" includes="KBase1">
    ...
  </kbase>
  ...
</kmodule>
```

--------------------------------

### Example Rule with Imported Average Function

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

This example shows how to import and use a custom 'average' function within a Drools rule to calculate the average profit. Ensure the AverageAccumulateFunction.AverageData class is available.

```drl
import accumulate AverageAccumulateFunction.AverageData average

rule "Average profit"
  when
    groupby( /orderItems[ $order : order, $cost : cost, $price : price ];
                $group: $order;
                $avgProfit : average( 1 - $cost / $price ) )
  then
    // Average profit for `$group` is `$avgProfit`.
end
```

--------------------------------

### Configure Stateless KIE Session

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Example configuration for a stateless KIE session in a kmodule.xml file. Use this when session state does not need to be persisted between invocations.

```xml
<kmodule>
  ...
  <kbase>
    ...
    <ksession name="KSession2_1" type="stateless" default="true" clockType="realtime">
    ...
  </kbase>
  ...
</kmodule>
```

--------------------------------

### Unary Test as Function Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/DMN/index.html

Demonstrates how unary tests can be used as first-class citizens, functioning like functions with an implicit single parameter. This example shows a 'is minor' test and its invocation.

```feel
{
      is minor : < 18,
      Bob is minor : is minor( bob.age )
  }
```

--------------------------------

### Event Met By Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Matches if eventB ends at the same time when eventA starts. The optional parameter sets the maximum distance between the end time of eventB and the start time of eventA. Drools does not support negative intervals for this operator.

```java
$eventA : EventA(this metby $eventB)
```

```java
abs($eventA.startTimestamp - $eventB.endTimestamp) == 0
```

```java
$eventA : EventA(this metby[5s] $eventB)
```

```java
abs($eventA.startTimestamp - $eventB.endTimestamp) <= 5s
```

--------------------------------

### Configure Trace Logging for MetricLogUtils

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Configure logback.xml to set the trace level for MetricLogUtils to capture detailed metric logs.

```xml
<configuration>
  <logger name="org.drools.metric.util.MetricLogUtils" level="trace"/>
  ...
<configuration>
```

--------------------------------

### Alternative DRL Syntax for Data Source Entry Point

Source: https://kie.apache.org/docs/10.1.x/drools/drools/migration-guide/index.html

Demonstrates an alternative DRL syntax for specifying data sources as entry points using standard DRL syntax instead of OOPath. This requires explicitly stating the object type even if inferable.

```drl
$l: LoanApplication( applicant.age >= 20, deposit >= 1000, amount ⇐ maxAmount ) from entry-point loanApplications

```

--------------------------------

### Event Meets Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Matches if eventA ends at the same time when eventB starts. The optional parameter sets the maximum time allowed between the end time of eventA and the start time of eventB. Drools does not support negative intervals for this operator.

```java
$eventA : EventA(this meets $eventB)
```

```java
abs($eventB.startTimestamp - $eventA.endTimestamp) == 0
```

```java
$eventA : EventA(this meets[5s] $eventB)
```

```java
abs($eventB.startTimestamp - $eventA.endTimestamp) <= 5s
```

--------------------------------

### Create KieScanner with File System Repository

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Create a KieScanner that monitors a specified folder on the file system for kjar updates. Jar files must follow Maven naming conventions.

```java
KieServices kieServices = KieServices.Factory.get();
KieScanner kScanner = kieServices.newKieScanner( kContainer, "/myrepo/kjars" );
```

--------------------------------

### Rule with 'from entry-point'

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Uses 'from entry-point' to define a specific data source for a pattern, typically used for event streams. This example checks a 'WithdrawRequest' against a 'CheckingAccount' from a specific entry point.

```drl
rule "Authorize withdrawal"
  when
    WithdrawRequest( $ai : accountId, $am : amount ) from entry-point "ATM Stream"
    CheckingAccount( accountId == $ai, balance > $am )
  then
    // Authorize withdrawal.
end
```

--------------------------------

### Implement LoanUnit POJO for Rule Unit Data

Source: https://kie.apache.org/docs/10.1.x/drools/drools/migration-guide/index.html

Implement a POJO that extends `RuleUnitData` to define facts for a rule unit. This example uses a `DataStore` to hold `LoanApplication` objects and an integer for a maximum amount.

```java
package org.kie.kogito.queries;

import org.kie.kogito.rules.DataSource;
import org.kie.kogito.rules.DataStore;
import org.kie.kogito.rules.RuleUnitData;

public class LoanUnit implements RuleUnitData {

   private int maxAmount;
   private DataStore<LoanApplication> loanApplications;

   public LoanUnit() {
   	this(DataSource.createStore(), 0);
   }

   public LoanUnit(DataStore<LoanApplication> loanApplications, int maxAmount) {
   	this.loanApplications = loanApplications;
   	this.maxAmount = maxAmount;
   }

   public DataStore<LoanApplication> getLoanApplications() { return loanApplications; }

   public void setLoanApplications(DataStore<LoanApplication> loanApplications) {
   	this.loanApplications = loanApplications;
   }

   public int getMaxAmount() { return maxAmount; }
   public void setMaxAmount(int maxAmount) { this.maxAmount = maxAmount; }
}

```

--------------------------------

### Event Overlapped By Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Matches if eventB starts before eventA and ends during eventA's time frame. The operator can take one parameter for maximum distance or two for minimum and maximum distance between eventA's start and eventB's end.

```java
$eventA : EventA(this overlappedby $eventB)
```

--------------------------------

### Event Overlaps Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Matches if eventA starts before eventB and ends during eventB's time frame. The operator can take one parameter for maximum distance or two for minimum and maximum distance between eventB's start and eventA's end.

```java
$eventA : EventA(this overlaps $eventB)
```

--------------------------------

### Event Coincidence Check with 'during' Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Use the 'during' operator to check if one event occurs entirely within the time frame of another. The current event must start after the correlated event starts and end before the correlated event ends.

```java
$eventA : EventA(this during $eventB)
```

```java
$eventB.startTimestamp < $eventA.startTimestamp <= $eventA.endTimestamp < $eventB.endTimestamp
```

--------------------------------

### Empty kmodule.xml Configuration

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

An empty kmodule.xml file is the simplest configuration. It must be placed in the resources/META-INF folder and will result in one default KieBase containing all Kie assets under the resources folder.

```xml
<?xml version="1.0" encoding="UTF-8"?>
<kmodule xmlns="http://www.drools.org/xsd/kmodule"/>
```

--------------------------------

### Event Inclusion Check with 'includes' Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Use the 'includes' operator to check if a correlated event occurs entirely within the time frame of the current event. The correlated event must start after the current event starts and end before the current event ends.

```java
$eventA : EventA(this includes $eventB)
```

```java
$eventA.startTimestamp < $eventB.startTimestamp <= $eventB.endTimestamp < $eventA.endTimestamp
```

--------------------------------

### EventA coincides with EventB

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Matches if the start and end timestamps of EventA and EventB are identical.

```java
$eventA : EventA(this coincides $eventB)
```

--------------------------------

### Utilize and Run KieModule using Meta Models - Java

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

This Java code demonstrates building a KieModule using meta-models. It defines ReleaseId, generates a pom.xml, configures KieBases and KieSessions via a kmodule.xml, and then builds and runs the session.

```java
KieServices ks = KieServices.Factory.get();
KieFileSystem kfs = ks.newKieFileSystem();

Resource ex1Res = ks.getResources().newFileSystemResource(getFile("named-kiesession"));
Resource ex2Res = ks.getResources().newFileSystemResource(getFile("kiebase-inclusion"));

ReleaseId rid = ks.newReleaseId("org.drools", "kiemodulemodel-example", "6.0.0-SNAPSHOT");
kfs.generateAndWritePomXML(rid);

KieModuleModel kModuleModel = ks.newKieModuleModel();
kModuleModel.newKieBaseModel("kiemodulemodel")
            .addInclude("kiebase1")
            .addInclude("kiebase2")
            .newKieSessionModel("ksession6");

kfs.writeKModuleXML(kModuleModel.toXML());
kfs.write("src/main/resources/kiemodulemodel/HAL6.drl", getRule());

KieBuilder kb = ks.newKieBuilder(kfs);
kb.setDependencies(ex1Res, ex2Res);
kb.buildAll(); // kieModule is automatically deployed to KieRepository if successfully built.
if (kb.getResults().hasMessages(Level.ERROR)) {
    throw new RuntimeException("Build Errors:\n" + kb.getResults().toString());
}

KieContainer kContainer = ks.newKieContainer(rid);

KieSession kSession = kContainer.newKieSession("ksession6");
kSession.setGlobal("out", out);

Object msg1 = createMessage(kContainer, "Dave", "Hello, HAL. Do you read me, HAL?");
kSession.insert(msg1);
kSession.fireAllRules();

Object msg2 = createMessage(kContainer, "Dave", "Open the pod bay doors, HAL.");
kSession.insert(msg2);
kSession.fireAllRules();

Object msg3 = createMessage(kContainer, "Dave", "What's the problem?");
kSession.insert(msg3);
kSession.fireAllRules();
javaCopied!

```

--------------------------------

### Create KieContainer from Classpath

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

To trigger the building of Kie artifacts, create a KieContainer. This example shows how to create a KieContainer that reads files to be built from the classpath.

```java
KieServices kieServices = KieServices.Factory.get();
KieContainer kContainer = kieServices.getKieClasspathContainer();
```

--------------------------------

### DRL6 Double Ampersand Infix Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example of using '&&' as an infix logical AND operator in DRL6.

```drl
( Person(age == 10)
      &&
     Person(age == 20) )
```

--------------------------------

### DRL6 Custom Operator Syntax

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example of using a custom operator in DRL6 without a prefix.

```drl
Person(addresses supersetOf $alice.addresses)
```

--------------------------------

### Rule Metadata Entry

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example of defining metadata for a rule. The '@' symbol is used for metadata columns.

```java
@ruleflow-group "early-payment"
```

--------------------------------

### Execute Collection using InsertElements Command

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

This demonstrates executing a collection by wrapping it in an InsertElements command for a stateless session. This is an alternative to the convenience API.

```java
ksession.execute( CommandFactory.newInsertElements( collection ) );
```

--------------------------------

### Drools Rule Unit DRL Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/getting-started/index.html

An example Drools Rule Language (DRL) file defining a rule unit, a rule to process measurements, and a query. The rule 'will execute per each Measurement having ID color' processes 'color' measurements and adds their values to a global 'controlSet'. The 'FindColor' query retrieves measurements with the ID 'color'.

```drl
package org.example;

unit MeasurementUnit;

rule "will execute per each Measurement having ID color"
when
	/measurements[ id == "color", $colorVal : val ]
then
	controlSet.add($colorVal);
end

query FindColor
    $m: /measurements[ id == "color" ]
end
```

--------------------------------

### Enable Beta Range Index in kbase

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Configure the kbase in kmodule.xml to enable beta range index for potential performance improvements with large fact joins.

```xml
<kbase name="KBase1" betaRangeIndex="enabled">
xml
```

--------------------------------

### DRL6 Double Pipe Infix Operator

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Example of using '||' as an infix logical OR operator in DRL6.

```drl
( Person(age == 10)
      ||
     Person(age == 20) )
```

--------------------------------

### Create DMNContext with Input Data

Source: https://kie.apache.org/docs/10.1.x/drools/drools/getting-started/index.html

Prepare input data for your DMN model by creating a `DMNContext`. You can use simple Maps or custom POJOs to represent input nodes like 'Driver' and 'Violation'.

```java
Map<String, ?> driver = of("Points", 2);
Map<String, ?> violation = of("Type", "speed", "Actual Speed", 120, "Speed Limit", 100);

DMNContext dmnContext = dmnRuntime.newContext();
dmnContext.set("Driver", driver);
dmnContext.set("Violation", violation);
```

--------------------------------

### Duration Attribute Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Sets a delay in milliseconds after which a rule can be activated, provided its conditions are still met.

```drl
duration 10000
```

--------------------------------

### Enabled Attribute Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Controls whether a rule is active. Set to 'true' to enable, 'false' to disable.

```drl
enabled true
```

--------------------------------

### EventA before EventB time calculation

Source: https://kie.apache.org/docs/10.1.x/drools/drools/rule-engine/index.html

Expresses the 'before' operator using the difference between event start and end timestamps.

```java
3m30s <= $eventB.startTimestamp - $eventA.endTimeStamp <= 4m
```

--------------------------------

### No-Loop Attribute Example

Source: https://kie.apache.org/docs/10.1.x/drools/drools/language-reference/index.html

Prevents a rule from reactivating itself if its consequences re-trigger its conditions. Set to 'true' to prevent looping.

```drl
no-loop true
```

--------------------------------

### Build KieModule and Create KieContainer

Source: https://kie.apache.org/docs/10.1.x/drools/drools/KIE/index.html

Initializes KieServices, builds all KieModules from a KieFileSystem, and creates a KieContainer for accessing KieBases and KieSessions.

```java
KieFileSystem kfs = ...
kieServices.newKieBuilder( kfs ).buildAll();
KieContainer kieContainer = kieServices.newKieContainer(kieServices.getRepository().getDefaultReleaseId());
```
Tokens:
Raw