无状态与流氓中的有状态会话行为

Question

我是流口水的新手。 我试图理解Drools提供的无状态和有状态会话之间的区别。

根据我最初的理解，

在无状态会话的情况下，如果在任何规则的动作执行期间修改了事实，则不会将其重新提交给推理引擎以找出与修改的事实匹配的新规则。

在有状态会话的情况下，如果在任何规则的动作执行期间修改了事实，则将其重新提交给推理引擎以找出与修改的事实匹配的新规则，然后将执行它们的相应动作。

因此，当我尝试通过编写示例规则来验证此行为时，我发现两种情况下的行为完全相同。 所以现在我对有状态会话和无状态会话之间的区别感到困惑。

我想请大家帮助我理解有状态和无状态会话的正确行为。

为了您的参考，我将粘贴有状态和无状态会话的示例代码及其输出和示例规则。

licenseApplication.drl   (Rule file)

package com.idal.droolsapp

rule "Is of valid age"
    no-loop
when
    $a : Applicant( age < 18 )
then
    System.out.println( "Not eligible for license" );
    System.out.println( "Setting Valid to false" );
    modify( $a ) { setValid( false ) };
end

rule "Is of valid false"
    salience 100
when
    $a : Applicant( valid == false )
then
    System.out.println( "Second rule fired" );
end

输入对象（Fact）Applicant.java

package com.idal.droolsapp;

public class Applicant {

    private String name;

    private int age;

    private boolean valid = true;

    public Applicant(String name, int age) {
        setName(name);
        setAge(age);
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getAge() {
        return age;
    }

    public void setValid(boolean valid) {
        this.valid = valid;
    }

    public boolean isValid() {
        return valid;
    }

    @Override
    public String toString() {
        return "Applicant [name=" + name + ", age=" + age + ", valid=" + valid
                + "]";
    }


}

StatelessSessionExample.java（无状态会话测试代码）

package com.idal.droolsapp;

import org.drools.KnowledgeBase;
import org.drools.KnowledgeBaseFactory;
import org.drools.builder.KnowledgeBuilder;
import org.drools.builder.KnowledgeBuilderFactory;
import org.drools.builder.ResourceType;
import org.drools.io.ResourceFactory;
import org.drools.runtime.StatelessKnowledgeSession;

public class StatelessSessionExample {

    /**
     * @param args
     */
    public static void main(String[] args) {

        KnowledgeBuilder kbuilder = KnowledgeBuilderFactory
                .newKnowledgeBuilder();

        kbuilder.add(ResourceFactory.newClassPathResource(
                "licenseApplication.drl", StatelessSessionExample.class),

        ResourceType.DRL);

        if (kbuilder.hasErrors()) {

            System.err.println(kbuilder.getErrors().toString());

        }

        KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();

        kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());

        StatelessKnowledgeSession ksession = kbase.newStatelessKnowledgeSession();

        Applicant applicant = new Applicant( "Mr John Smith", 16 );

        ksession.execute( applicant );

        System.out.println("Updated Applicant = " + applicant);
    }

}

无状态会话测试代码的输出：

 Not eligible for license Setting Valid to false Second rule fired Updated Applicant = Applicant [name=Mr John Smith, age=16, valid=false] 

StatefulSessionExample.java（无状态会话测试代码）

package com.idal.droolsapp;

import org.drools.KnowledgeBase;
import org.drools.KnowledgeBaseFactory;
import org.drools.builder.KnowledgeBuilder;
import org.drools.builder.KnowledgeBuilderFactory;
import org.drools.builder.ResourceType;
import org.drools.io.ResourceFactory;
import org.drools.runtime.StatefulKnowledgeSession;

public class StatefulSessionExample {

    /**
     * @param args
     */
    public static void main(String[] args) {

        KnowledgeBuilder kbuilder = KnowledgeBuilderFactory
                .newKnowledgeBuilder();

        kbuilder.add(ResourceFactory.newClassPathResource(
                "licenseApplication.drl", StatefulSessionExample.class),

        ResourceType.DRL);

        if (kbuilder.hasErrors()) {

            System.err.println(kbuilder.getErrors().toString());

        }

        KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();

        kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());

        StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();

        Applicant applicant = new Applicant( "Mr John Smith", 16 );

        ksession.insert( applicant );

        ksession.fireAllRules();

        ksession.dispose();

        System.out.println("Updated Applicant = " + applicant);
    }

}

有状态会话测试代码的输出：

 Not eligible for license Setting Valid to false Second rule fired Updated Applicant = Applicant [name=Mr John Smith, age=16, valid=false] 

再次要求每个人帮助我理解有状态和无状态会话的正确行为。

在此先感谢Manish Gandhi

Answer 1

据我所知，当您在无状态会话中触发规则时，更改不会触发新规则。 但这并不意味着规则不会因为变化而被解雇。 第一个规则更改有效值，这意味着当您检查第二个规则的条件时，有效已经为假并且规则触发。

如果更改影响了先前规则的“何时”部分，则在无状态会话中，第一个规则将不会被第二次触发，而第一个规则将在第一个规则中触发。