Merge branch 'master' of https://github.com/JonCook/tutorials

rule-engines/README.md

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+## Rule Engines
+
+This module contains articles about rule engines. Articles specific to a given rule engine go in the relevant submodule.
+
+### Relevant articles:
+
+- [List of Rules Engines in Java](https://www.baeldung.com/java-rule-engines)

rule-engines/easy-rules/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.easyrules</groupId>
+    <artifactId>easy-rules</artifactId>
+    <version>1.0</version>
+    <name>easy-rules</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../..</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.jeasy</groupId>
+            <artifactId>easy-rules-core</artifactId>
+            <version>${easy-rules.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <easy-rules.version>3.0.0</easy-rules.version>
+    </properties>
+</project>

rule-engines/easy-rules/src/main/java/com/baeldung/easyrules/HelloWorldRule.java

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+package com.baeldung.easyrules;
+
+import org.jeasy.rules.annotation.Action;
+import org.jeasy.rules.annotation.Condition;
+import org.jeasy.rules.annotation.Rule;
+
+@Rule(name = "Hello World rule", description = "Always say hello world")
+public class HelloWorldRule {
+
+    @Condition
+    public boolean when() {
+        return true;
+    }
+
+    @Action
+    public void then() throws Exception {
+        System.out.println("hello world");
+    }
+
+}

rule-engines/easy-rules/src/main/java/com/baeldung/easyrules/Launcher.java

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+package com.baeldung.easyrules;
+
+import org.jeasy.rules.api.Facts;
+import org.jeasy.rules.api.Rules;
+import org.jeasy.rules.api.RulesEngine;
+import org.jeasy.rules.core.DefaultRulesEngine;
+
+public class Launcher {
+    public static void main(String... args) {
+        // create facts
+        Facts facts = new Facts();
+
+        // create rules
+        Rules rules = new Rules();
+        rules.register(new HelloWorldRule());
+
+        // create a rules engine and fire rules on known facts
+        RulesEngine rulesEngine = new DefaultRulesEngine();
+        rulesEngine.fire(rules, facts);
+    }
+}

rule-engines/easy-rules/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

rule-engines/openl-tablets/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.openltablets</groupId>
+    <artifactId>openl-tablets</artifactId>
+    <version>1.0</version>
+    <name>openl-tablets</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../..</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.openl</groupId>
+            <artifactId>org.openl.core</artifactId>
+            <version>${openl.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openl.rules</groupId>
+            <artifactId>org.openl.rules</artifactId>
+            <version>${openl.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <openl.version>5.19.4</openl.version>
+    </properties>
+
+</project>

rule-engines/openl-tablets/src/main/java/com/baeldung/openltablets/model/Case.java

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+package com.baeldung.openltablets.model;
+
+public class Case {
+
+    private User user;
+    private int hourOfDay;
+
+    public User getUser() {
+        return user;
+    }
+
+    public void setUser(final User user) {
+        this.user = user;
+    }
+
+    public int getHourOfDay() {
+        return hourOfDay;
+    }
+
+    public void setHourOfDay(final int hourOfDay) {
+        this.hourOfDay = hourOfDay;
+    }
+}

rule-engines/openl-tablets/src/main/java/com/baeldung/openltablets/model/Greeting.java

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+package com.baeldung.openltablets.model;
+
+public enum Greeting {
+
+    GOOD_MORNING("Good Morning"),
+    GOOD_AFTERNOON("Good Afternoon"),
+    GOOD_EVENING("Good Evening"),
+    GOOD_NIGHT("Good Night");
+
+    private final String literal;
+
+    private Greeting(final String literal) {
+        this.literal = literal;
+    }
+
+    public String getLiteral() {
+        return literal;
+    }
+
+}

rule-engines/openl-tablets/src/main/java/com/baeldung/openltablets/model/User.java

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+package com.baeldung.openltablets.model;
+
+public class User {
+
+    private String name;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(final String name) {
+        this.name = name;
+    }
+}

rule-engines/openl-tablets/src/main/java/com/baeldung/openltablets/rules/IRule.java

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+package com.baeldung.openltablets.rules;
+
+import com.baeldung.openltablets.model.Case;
+
+public interface IRule {
+    void helloUser(final Case aCase, final Response response);
+}

rule-engines/openl-tablets/src/main/java/com/baeldung/openltablets/rules/Main.java

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+package com.baeldung.openltablets.rules;
+
+
+import java.time.LocalDateTime;
+
+import org.openl.rules.runtime.RulesEngineFactory;
+import org.openl.runtime.EngineFactory;
+
+import com.baeldung.openltablets.model.Case;
+import com.baeldung.openltablets.model.User;
+
+public class Main {
+    private IRule instance;
+
+    public static void main(String[] args) {
+        Main rules = new Main();
+        User user = new User();
+        user.setName("Donald Duck");
+        Case aCase = new Case();
+        aCase.setUser(user);
+        aCase.setHourOfDay(23);
+        rules.process(aCase);
+    }
+
+    public void process(Case aCase) {
+        final EngineFactory<IRule> engineFactory = new RulesEngineFactory<IRule>(getClass().getClassLoader()
+            .getResource("openltablets/HelloUser.xls"), IRule.class);
+        instance = engineFactory.newEngineInstance();
+        instance.helloUser(aCase, new Response());
+    }
+}

rule-engines/openl-tablets/src/main/java/com/baeldung/openltablets/rules/Response.java

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+package com.baeldung.openltablets.rules;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Response {
+    private String result;
+    private Map<String, String> map = new HashMap<>();
+    
+    public Response() { }
+    
+    public String getResult() {
+        return result;
+    }
+
+    public void setResult(final String s) {
+        result = s;
+    }
+
+    public Map<String, String> getMap() {
+        return map;
+    }
+
+}

rule-engines/openl-tablets/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

rule-engines/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>rule-engines</artifactId>
+    <name>rule-engines</name>
+    <packaging>pom</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>..</relativePath>
+    </parent>
+
+    <modules>
+        <module>easy-rules</module>
+        <module>openl-tablets</module>
+        <module>rulebook</module>
+    </modules>
+
+</project>

rule-engines/rulebook/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.rulebook</groupId>
+    <artifactId>rulebook</artifactId>
+    <version>1.0</version>
+    <name>rulebook</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../..</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.deliveredtechnologies</groupId>
+            <artifactId>rulebook-core</artifactId>
+            <version>${rulebook.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <rulebook.version>0.6.2</rulebook.version>
+    </properties>
+
+</project>

rule-engines/rulebook/src/main/java/com/baeldung/rulebook/HelloWorldRule.java

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+package com.baeldung.rulebook;
+
+import com.deliveredtechnologies.rulebook.lang.RuleBookBuilder;
+import com.deliveredtechnologies.rulebook.model.RuleBook;
+
+public class HelloWorldRule {
+    public RuleBook<Object> defineHelloWorldRules() {
+
+        return RuleBookBuilder.create()
+            .addRule(rule -> rule.withNoSpecifiedFactType()
+                .then(f -> System.out.print("Hello ")))
+            .addRule(rule -> rule.withNoSpecifiedFactType()
+                .then(f -> System.out.println("World")))
+            .build();
+
+    }
+}

rule-engines/rulebook/src/main/java/com/baeldung/rulebook/Launcher.java

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+package com.baeldung.rulebook;
+
+import com.deliveredtechnologies.rulebook.FactMap;
+
+public class Launcher {
+
+    public static void main(String[] args) {
+        HelloWorldRule ruleBook = new HelloWorldRule();
+        ruleBook.defineHelloWorldRules()
+            .run(new FactMap<>());
+    }
+}

rule-engines/rulebook/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>