Procedure 6.1. Create and Execute your First Rule using plain Java

1. Create your fact model

   Create a POJO based on which your rule runs. For example, create a Person.java file in a directory called my-project. The Person class contains the getter and setter methods to retrieve and set values of first name, last name, hourly rate, and wage of a person:

   import org.kie.api.KieServices;
   import org.kie.api.runtime.KieContainer;
   import org.kie.api.runtime.KieSession;
   
     public class Person {
       private String firstName;
       private String lastName;
       private Integer hourlyRate;
       private Integer wage;
   
         public String getFirstName() {
       	  return firstName;
       	}
   
       	public void setFirstName(String firstName) {
       	  this.firstName = firstName;
       	}
   
       	public String getLastName() {
       	  return lastName;
       	}
   
       	public void setLastName(String lastName) {
       	  this.lastName = lastName;
       	}
   
       	public Integer getHourlyRate() {
       	  return hourlyRate;
       	}
   
       	public void setHourlyRate(Integer hourlyRate) {
       	  this.hourlyRate = hourlyRate;
       	}
   
       	public Integer getWage(){
       	  return wage;
       	}
   
       	public void setWage(Integer wage){
       	  this.wage = wage;
       	}
       }

2. Create your rule

   Create your rule file in .drl format under my-project directory. Here is the simple rule file called Person.drl, which does a calculation on the wage and hourly rate values and displays a message based on the result.

   dialect "java"
   
   rule "Wage"
   
     when
   
       Person(hourlyRate*wage > 100)
       Person(name : firstName, surname : lastName)
   
     then
       System.out.println( "Hello" + " " + name + " " + surname + "!" );
       System.out.println( "You are rich!" );
   
   end

3. Create a main class

   Create your main class (say, DroolsTest.java) and save it in the same my-project directory as your POJO. This file will load the knowledge base and fire your rules:
   In the DroolsTest.java file:
   1. Add the following import statements to import the KIE services, container, and session:

      import org.kie.api.KieServices;
      import org.kie.api.runtime.KieContainer;
      import org.kie.api.runtime.KieSession;

   2. Load the knowledge base and fire your rule from the main() method:

      public class DroolsTest {
          public static final void main(String[] args) {
            try {
              // load up the knowledge base
              KieServices ks = KieServices.Factory.get();
              KieContainer kContainer = ks.getKieClasspathContainer();
              KieSession kSession = kContainer.newKieSession();
      
              // go !
              Person p = new Person();
              p.setWage(12);
              p.setFirstName("Tom");
              p.setLastName("Summers");
              p.setHourlyRate(10);
      
              kSession.insert(p);
              kSession.fireAllRules();
              }
      
            catch (Throwable t) {
              t.printStackTrace();
            }
          }
      }

      The main() method passes the model to the rule, which contains the first name, last name, wage, and hourly rate.

4. Download the BRMS Engine jar files

   Download the BRMS engine jar files and save them under my-project/BRMS-engine-jars/. These files are available from the Red Hat Customer Portal under the generic deployable version.

5. Create the kmodule.xml metadata file

   Create a file called kmodule.xml under my-project/META-INF to create the default session. At the minimum, this file contains the following:

   <?xml version="1.0" encoding="UTF-8"?>
   <kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule">
   </kmodule>

6. Build your example

   Navigate to the my-project directory and execute the following command from the command line:

   javac -classpath "./BRMS-engine-jars/*:." DroolsTest.java

   This will compile and build your java files.

7. Run your example

   If there were no compilation errors, you can now run the DroolsTest to execute your rule:

   java -classpath "./BRMS-engine-jars/*:." DroolsTest

   The expected output is:

   Hello Tom Summers!
   You are rich!

Procedure 6.2. Create and Execute your First Rule using Maven

1. Create a basic Maven archetype

   Navigate to a directory of choice in your system and execute the following command:

   mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app  -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

   This creates a directory called my-app with the following structure:

   my-app
   |-- pom.xml
   `-- src
       |-- main
       |   `-- java
       |       `-- com
       |           `-- mycompany
       |               `-- app
       |                   `-- App.java
       `-- test
           `-- java
               `-- com
                   `-- mycompany
                       `-- app
                           `-- AppTest.java

   The my-app directory comprises:

   • A src/main directory for storing your application's sources.
   • A src/test directory for storing your test sources.
   • A pom.xml file containing the Project Object Model (POM) for your project. At this stage, the pom.xml file contains the following:

     <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/maven-v4_0_0.xsd">
       <modelVersion>4.0.0</modelVersion>
       <groupId>com.sample.app</groupId>
       <artifactId>my-app</artifactId>
       <packaging>jar</packaging>
       <version>1.0-SNAPSHOT</version>
       <name>my-app</name>
       <url>http://maven.apache.org</url>
       <dependencies>
         <dependency>
           <groupId>junit</groupId>
           <artifactId>junit</artifactId>
           <version>3.8.1</version>
           <scope>test</scope>
         </dependency>
       </dependencies>
     </project>

2. Create your Fact Model

   Once you are done with the archetype, create a class based on which your rule runs. Create the POJO called Person.java file under my-app/src/main/java/com/mycompany/app folder. This class contains the getter and setter methods to retrieve and set values of first name, last name, hourly rate, and wage of a person.

   package com.mycompany.app;
   
     public class Person {
   
       private String firstName;
       private String lastName;
       private Integer hourlyRate;
       private Integer wage;
   
   
       public String getFirstName() {
         return firstName;
       }
   
       public void setFirstName(String firstName) {
         this.firstName = firstName;
       }
   
       public String getLastName() {
         return lastName;
       }
   
       public void setLastName(String lastName) {
         this.lastName = lastName;
       }
   
       public Integer getHourlyRate() {
         return hourlyRate;
       }
   
       public void setHourlyRate(Integer hourlyRate) {
         this.hourlyRate = hourlyRate;
       }
   
       public Integer getWage(){
         return wage;
       }
   
       public void setWage(Integer wage){
         this.wage = wage;
       }
   
     }

3. Create your rule

   Create your rule file in .drl format under my-app/src/main/resources/rules.
   Here is the simple rule file called Person.drl, which imports the Person class:

   package com.mycompany.app;
   import com.mycompany.app.Person;
   
   dialect "java"
   
   rule "Wage"
   
     when
       Person(hourlyRate*wage > 100)
       Person(name : firstName, surname : lastName)
   
     then
       System.out.println( "Hello " + name + " " + surname + "!" );
       System.out.println( "You are rich!" );
   
   end

   As before, this rule does a simple calculation on the wage and hourly rate values and displays a message based on the result.

4. Create the kmodule.xml metadata file

   Create an empty file called kmodule.xml under my-app/src/main/resources/META-INF to create the default session. This file contains the following:

   <?xml version="1.0" encoding="UTF-8"?>
   <kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule">
   </kmodule>

5. Set project dependencies in the pom.xml configuration file

   As Maven manages the classpath through this configuration file, you must declare in it the libraries your application requires. Edit the my-app/pom.xml file to set the JBoss BRMS dependencies and setup the GAV values for your application, as shown below:

   <?xml version="1.0" encoding="UTF-8"?>
   <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.mycompany.app</groupId>
   <artifactId>my-app</artifactId>
   <version>1.0.0</version>
   <repositories>
     <repository>
       <id>jboss-ga-repository</id>
       <url>http://maven.repository.redhat.com/techpreview/all</url>
     </repository>
   </repositories>
   <dependencies>
     <dependency>
       <groupId>org.drools</groupId>
       <artifactId>drools-compiler</artifactId>
       <version>LATEST</version>
     </dependency>
     <dependency>
       <groupId>org.kie</groupId>
       <artifactId>kie-api</artifactId>
       <version>LATEST</version>
     </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.11</version>
       <scope>test</scope>
     </dependency>
   </dependencies>
   </project>

6. Test it!

   After you add the dependencies in the pom.xml file, use the testApp method of the my-app/src/test/java/com/mycompany/app/AppTest.java (which is created by default by Maven) to instantiate and test the rule.
   In the AppTest.java file:
   1. Add the following import statements to import the KIE services, container, and session:

      import org.kie.api.KieServices;
      import org.kie.api.runtime.KieContainer;
      import org.kie.api.runtime.KieSession;

   2. Load the knowledge base and fire your rule from the testApp() method:

      public void testApp() {
      
        // load up the knowledge base
        KieServices ks = KieServices.Factory.get();
        KieContainer kContainer = ks.getKieClasspathContainer();
        KieSession kSession = kContainer.newKieSession();
      
        // set up our Person fact model
        Person p = new Person();
        p.setWage(12);
        p.setFirstName("Tom");
        p.setLastName("Summers");
        p.setHourlyRate(10);
      
        // insert him into the session
        kSession.insert(p);
      
        // and fire all rules on him
        kSession.fireAllRules();
      
        // we can assert here, but the rule itself should output something since the person's wage is more than our baseline rule
      }
      

      The testApp() method passes the model to the rule, which contains the first name, last name, wage, and hourly rate.

7. Build your example

   Navigate to the my-app directory and execute the following command from the command line:

   mvn clean install

   When you run this command for the first time, it may take a while as Maven downloads all the artifacts required for this project such as JBoss BRMS jar files.
   The expected output is:

   Hello Tom Summers!
   You are rich!
   Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.194 sec
   
   Results :
   
   Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
   
   [INFO]
   ...
   
   [INFO] ------------------------------------------------------------------------
   [INFO] BUILD SUCCESS
   [INFO] ------------------------------------------------------------------------
   [INFO] Total time: 6.393 s
   ...
   [INFO] ------------------------------------------------------------------------
   
   

Procedure 6.3. Create and Execute your First Rule using JBoss Developer Studio

1. Create a BRMS Project.

   1. Start JBoss Developer Studio and navigate to File → New → Project.
      This opens a New Project dialog box.
   2. In the New Project dialog box, select Drools → Drools Project and click Next.
   3. Type a name for your project and click Next.
      The New Project dialog box provides you choice to add some default artifacts to your project, such as sample rules, decision tables and Java classes for them. Let us select the first two check boxes and click Next.
   4. Select the configured BRMS runtime in the Drools Runtime dialog box. If you have not already configured your BRMS runtime, click Configure Workspace Settings... link and configure the BRMS runtime jars.
   5. Select Drools 6.0.x for Generate code compatible with: field and provide values for groupId, artifactId, and version. These values form your project's fully qualified artifact name. Let us provide the following values:
      • groupId: com.mycompany.app
      • artifactId: my-app
      • version: 1.0.0
   6. Click Finish.
      This sets up a basic project structure, classpath and sample rules for you to get started with.

      My-Project
      `-- src/main/java
          |-- com.sample
          |   `-- DroolsTest.java
          |
       `-- src/main/rules
          | -- Sample.drl
          |
        `-- JRE System Library
          |
        `-- Drools Library
          |
        `-- src
          |
        `-- pom.xml

      This newly created project called My-Project comprises the following:

      • A rule file called Sample.drl under src/main/rules directory.
      • An example java file called DroolsTest.java under src/main/java in the com.sample package. You can use the DroolsTest class to execute your rules in the BRMS engine.
      • The Drools Library directory. This acts as a custom classpath container that contains all the other jar files necessary for execution.

2. Create your fact model

   The sample DroolsTest.java file contains a sample POJO called Message with getter and setter methods. You can edit this class or create another similar POJO. Let us remove this POJO and create a new POJO called Person, which sets and retrieves values of first name, last name, hourly rate, and wage of a person:

   public static class Person {
          	  private String firstName;
          	  private String lastName;
          	  private Integer hourlyRate;
          	  private Integer wage;
   
          	  public String getFirstName() {
          	    return firstName;
          	  }
   
          	  public void setFirstName(String firstName) {
          	    this.firstName = firstName;
          	  }
   
          	  public String getLastName() {
          	    return lastName;
          	  }
   
          	  public void setLastName(String lastName) {
          	    this.lastName = lastName;
          	  }
   
          	  public Integer getHourlyRate() {
          	    return hourlyRate;
          	  }
   
          	  public void setHourlyRate(Integer hourlyRate) {
          	    this.hourlyRate = hourlyRate;
          	  }
   
          	  public Integer getWage(){
          	    return wage;
          	  }
   
          	  public void setWage(Integer wage){
          	    this.wage = wage;
          	  }

3. Update the main method

   The sample DroolsTest.java file contains a main() method that loads up the knowledge base and fires the rules. Update this main() method to pass the Person object to the rule:

     public static final void main(String[] args) {
         try {
           // load up the knowledge base
             KieServices ks = KieServices.Factory.get();
             KieContainer kContainer = ks.getKieClasspathContainer();
             KieSession kSession = kContainer.newKieSession("ksession-rules");
   
           // go !
             Person p = new Person();
             p.setWage(12);
             p.setFirstName("Tom");
             p.setLastName("Summers");
             p.setHourlyRate(10);
   
             kSession.insert(p);
             kSession.fireAllRules();
   
             }
   
           catch (Throwable t) {
             t.printStackTrace();
           }
       }

   Note

   To load the knowledge base, you first get the KieServices instance and the classpath based KieContainer. Then you build your KieSession with the KieContainer. Here, we are passing the session name ksession-rules that matches the one defined in kmodule.xml file.

4. Create your rule

   The sample rule file Sample.drl contains a basic skeleton of a rule. You can edit this file or create a new one to write your own rule.
   In your rule file:
   1. Include the package name:

      package com.sample
      

   2. Import facts into the rule:

      import com.sample.DroolsTest.Person;

   3. Create the rule in "when", "then" format.

      dialect "java"
      
      rule "Wage"
      
          when
            Person(hourlyRate*wage > 100)
            Person(name : firstName, surname : lastName)
      
          then
            System.out.println( "Hello" + " " + name + " " + surname + "!" );
            System.out.println( "You are rich!" );
      
      end
      

5. Test your rule

   Right-click the DroolsTest.java file and select Run As → Java Application.

Procedure 6.4. Create and Execute your First Rule using Business Central

1. Login to Business Central

   1. On the command line, move into the $SERVER_HOME/bin/ directory and execute the following command for Unix environment:

      ./standalone.sh

      for Windows environment:

      ./standalone.bat

   2. Once your server is up and running, open the following in a web browser:

      http://localhost:8080/business-central

      This opens the Business Central login page.
   3. Log in to the Business Central with the user credentials created during installation.

2. Create a repository structure and create a project under it

   1. On the main menu of Business Central, go to Authoring → Administration.
   2. Click Organizational Units → Manage Organizational Units, then click Add.
   3. Click Organizational Units → Manage Organizational Units, then click Add.
   4. In the displayed Add New Organizational Unit dialog box, define the unit properties. For example:

      • Name: EmployeeWage
      • Owner: Employee
      Click OK.
   5. On the perspective menu, click Repositories → New repository.
   6. In the displayed Create Repository dialog box, define the repository properties. For example:

      • Repository Name: EmployeeRepo
      • Organizational Unit: EmployeeWage
      Click Finish.
   7. Go to Authoring → Project Authoring.
   8. In the Project Explorer, under the organizational unit drop-down box, select EmployeeWage, and in the repository drop-down box select EmployeeRepo.
   9. On the perspective menu, go to New Item → Project.
   10. In the displayed Create new Project dialog box, provide a name (for example, MyProject) for your project properties and click Ok.
   11. In the New Project dialog box, define the maven properties of the Project. For example:

       • Group ID: org.bpms
       • Artifact ID: MyProject
       • Version ID: 1.0.0
       Click Finish.

3. Create a fact model

   1. On the perspective menu, go to New Item → Data Object.
   2. In the displayed Create new Data Object dialog box, provide the values for object name and package. For example:

      • Data Object: Person
      • Package: org.bpms.myproject
      Click Ok.
   3. In the displayed Create new field window of the newly created Person data object. Click add field to open New field dialogue. Add a variable name in the Id field, select data type for the variable in the Type field, and click Create and continue until you have defined all the necessary variables. For example:
      • Id: firstName
        Type: String
      • Id: lastName
        Type: String
      • Id: hourlyRate
        Type: Integer
      • Id: wage
        Type: Integer
      Click Create for the last variable and then Save.

4. Create a rule

   1. On the perspective menu, click New Item → DRL File.
   2. In the Create new dialog box, provide the name and package name of your rule file. For example:
      • DRL file name: MyRule
      • Package: org.bpms.myproject
      Click Ok.
   3. In the displayed DRL editor with the MyRule.drl file, write your rule as shown below:

      package org.bpms.myproject;
      rule "MyRule"
      ruleflow-group "MyProjectGroup"
        when
      
          Person(hourlyRate*wage > 100)
          Person(name : firstName, surname : lastName)
      
        then
          System.out.println( "Hello" + " " + name + " " + surname + "!" );
          System.out.println( "You are rich!" );
      
      end

   4. Click Save.

5. Create a Business Process and add a Business Rule Task

   1. On the main menu of Business Central, go to Authoring → Project Authoring.
   2. In the Create new Business Process dialog box, provide values for Business Process name and package. For example:
      • Business Process: MyProcess
      • Package: org.bpms.myproject
      Click Ok
      The Process Designer with the canvas of the created Process definition opens.
   3. Click on the white canvas. Expand the Properties palette on the right-hand side of the canvas. When you click in the Variable Definitions field, Editor for Variable Definitions opens:

      • Click Add Variable
      • In the Name column, enter person_proc
      • In the Defined Types column, select Person [org.bpms.myproject]

      Click Ok.
   4. Expand the Object Library palette with Process Elements on the left-hand side of the canvas.
   5. From the Object Library, navigate to Tasks and drag a Business Rule Task to the canvas. Next, navigate to End Events and drag the None end event to the canvas.
   6. Integrate the Business Rule task and the Start and End events into the process workflow. Click the Start event. Then, click Edge - Drag and drag it to the Business Rule Task. This connects the two objects. Do the same to connect the Business Rule Task to the End event.
   7. Select the Business Rule Task and set the following properties in the Properties panel under Core Properties:
      • Name:Rule_Task
      • Ruleflow Group: when you click in the Ruleflow Group field, an editor for Ruleflow Groups opens:

        • In the Ruleflow Group Name column, select MyProjectGroup
        • In the Rules column, select MyRule.drl
        • Click Save
      • Assignments
        When you click in the Assignments field, the Rule_Task Data I/O opens. Click Add under Data Inputs and Assignments and provide the data input elements. For example:
        • Name:person_Task
        • Data Type:Person[org.bpms.myproject]
        • Source: person_proc
          Click Save.
      • Click Generate all Forms ( ).
      • Save the Process.

6. Build and deploy your rule

   1. Open Project Editor and click Build & Deploy.
      A green notification appears in the upper part of the screen informing you that the project has been built and deployed successfully to the Execution Server.
   2. Go to Process Management → Process Definitions.
      You can see your newly built process listed in the Process Definitions window.
   3. Click button under Actions to start your Process.
      A MyProcess dialog box opens.
   4. In the MyProcess dialog box, provide the following values of the variables defined in your fact model and click Submit:
      • firstName: Tom
      • hourlyRate: 12
      • lastName: Summers
      • wage: 10
      As these values satisfy the rule condition, the expected output at the console is:

      16:19:58,479 INFO  [org.jbpm.kie.services.impl.store.DeploymentSynchronizer] (http-/127.0.0.1:8080-1) Deployment unit org.bpms:MyProject:1.0 stored successfully
      16:26:56,119 INFO  [stdout] (http-/127.0.0.1:8080-5) Hello Tom Summers!
      16:26:56,119 INFO  [stdout] (http-/127.0.0.1:8080-5) You are rich!
      

Procedure 6.5. Task

1. Generate a sample spreadsheet that you can use as the base.
2. If the JBoss BRMS plug-in is being used, use the wizard to generate a spreadsheet from a template.
3. Use an XSL-compatible spreadsheet editor to modify the XSL.

Procedure 8.1. Task

1. Open the integration code that is calling the rule engine.
2. Obtain your emailService object and then set it in the working memory.
3. In the DRL, declare that you have a global of type emailService and give it the name "email".
4. In your rule consequences, you can use things like email.sendSMS(number, message).

   Warning

   Globals are not designed to share data between rules and they should never be used for that purpose. Rules always reason and react to the working memory state, so if you want to pass data from rule to rule, assert the data as facts into the working memory.

   Important

   Do not set or change a global value from inside the rules. We recommend to you always set the value from your application using the working memory interface.

Procedure 8.2. Configure Transitive Closures

1. First, create some java rules to develop reasoning for transitive items. It inserts each of the locations.
2. Next, create the Location class; it has the item and where it is located.
3. Type the rules for the House example as depicted below:

   	ksession.insert( new Location("office", "house") );
   	ksession.insert( new Location("kitchen", "house") );
   	ksession.insert( new Location("knife", "kitchen") );
   	ksession.insert( new Location("cheese", "kitchen") );
   	ksession.insert( new Location("desk", "office") );
   	ksession.insert( new Location("chair", "office") );
   	ksession.insert( new Location("computer", "desk") );
   	ksession.insert( new Location("drawer", "desk") );
   

4. A transitive design is created in which the item is in its designated location such as a "desk" located in an "office."
   

   Figure 8.4. Transitive Reasoning Graph of a House.

Procedure 8.3. Define a Query

1. Create a query to look at the data inserted into the rules engine:

            query isContainedIn( String x, String y )
              Location( x, y; )
              or
              ( Location( z, y; ) and isContainedIn( x, z; ) )
            end
   

   Notice how the query is recursive and is calling "isContainedIn."
2. Create a rule to print out every string inserted into the system to see how things are implemented. The rule should resemble the following format:

            rule "go" salience 10
            when
                $s : String( )
            then
                System.out.println( $s );
            end
   

3. Using Step 2 as a model, create a rule that calls upon the Step 1 query "isContainedIn."

            rule "go1"
            when
                String( this == "go1" )
                isContainedIn("office", "house"; )
            then
                System.out.println( "office is in the house" );
            end
   

   The "go1" rule will fire when the first string is inserted into the engine. That is, it asks if the item "office" is in the location "house." Therefore, the Step 1 query is evoked by the previous rule when the "go1" String is inserted.
4. Create the "go1," insert it into the engine, and call the fireAllRules.

            ksession.insert( "go1" );
            ksession.fireAllRules();
            ---
            go1
            office is in the house
   

   The --- line indicates the separation of the output of the engine from the firing of the "go" rule and the "go1" rule.
   • "go1" is inserted
   • Salience ensures it goes first
   • The rule matches the query

Procedure 8.4. Create a Transitive Closure

1. Create a Transitive Closure by implementing the following rule:

            rule "go2"
            when
            	String( this == "go2" )
            	isContainedIn("drawer", "house"; )
            then
            	System.out.println( "Drawer in the House" );
            end
   

2. Recall from the Cloning Transitive Closure's topic, there was no instance of "drawer" in "house." "drawer" was located in "desk."
   

   Figure 8.5. Transitive Reasoning Graph of a Drawer.

3. Use the previous query for this recursive information.

            query isContainedIn( String x, String y )
            	Location( x, y; )
            	or
            	( Location( z, y; ) and isContainedIn( x, z; ) )
            end
   

4. Create the "go2," insert it into the engine, and call the fireAllRules.

            ksession.insert( "go2" );
            ksession.fireAllRules();
            ---
            go2
            Drawer in the House
   

   When the rule is fired, it correctly tells you "go2" has been inserted and that the "drawer" is in the "house."
5. Check how the engine determined this outcome.
   • The query has to recurse down several levels to determine this.
   • Instead of using Location( x, y; ), The query uses the value of (z, y; ) since "drawer" is not in "house."
   • The z is currently unbound which means it has no value and will return everything that is in the argument.
   • y is currently bound to "house," so z will return "office" and "kitchen."
   • Information is gathered from "office" and checks recursively if the "drawer" is in the "office." The following query line is being called for these parameters: isContainedIn (x ,z; )
   There is no instance of "drawer" in "office;" therefore, it does not match. With z being unbound, it will return data that is within the "office," and it will gather that z == desk.

            isContainedIn(x==drawer, z==desk)
   

   isContainedIn recurses three times. On the final recurse, an instance triggers of "drawer" in the "desk."

            Location(x==drawer, y==desk)
   

   This matches on the first location and recurses back up, so we know that "drawer" is in the "desk," the "desk" is in the "office," and the "office" is in the "house;" therefore, the "drawer" is in the "house" and returns true.

Procedure 8.5. Create a Reactive Transitive Query

1. Create a Reactive Transitive Query by implementing the following rule:

            rule "go3"
            when
              String( this == "go3" )
              isContainedIn("key", "office"; )
            then
              System.out.println( "Key in the Office" );
            end
   

   Reactive Transitive Queries can ask a question even if the answer can not be satisfied. Later, if it is satisfied, it will return an answer.

   Note

   Recall from the Cloning Transitive Closures example that there was no "key" item in the system.
2. Use the same query for this reactive information.

            query isContainedIn( String x, String y )
              Location( x, y; )
              or
              ( Location( z, y; ) and isContainedIn( x, z; ) )
            end
   

3. Create the "go3," insert it into the engine, and call the fireAllRules.

            ksession.insert( "go3" );
            ksession.fireAllRules();
            ---
            go3
   

   • "go3" is inserted
   • fireAllRules(); is called
   The first rule that matches any String returns "go3" but nothing else is returned because there is no answer; however, while "go3" is inserted in the system, it will continuously wait until it is satisfied.
4. Insert a new location of "key" in the "drawer":

            ksession.insert( new Location("key", "drawer") );
            ksession.fireAllRules();
            ---
            Key in the Office
   

   This new location satisfies the transitive closure because it is monitoring the entire graph. In addition, this process now has four recursive levels in which it goes through to match and fire the rule.

Procedure 8.6. Create an Unbound Argument's Query

1. Create a Query with Unbound Arguments by implementing the following rule:

            rule "go4"
            when
              String( this == "go4" )
              isContainedIn(thing, "office"; )
            then
              System.out.println( "thing" + thing + "is in the Office" );
            end
   

   This rule is asking for everything in the "office," and it will tell everything in all the rows below. The unbound argument (out variable thing) in this example will return every possible value; accordingly, it is very similar to the z value used in the Reactive Transitive Query example.
2. Use the query for the unbound arguments.

            query isContainedIn( String x, String y )
              Location( x, y; )
              or
              ( Location( z, y; ) and isContainedIn( x, z; ) )
            end
   

3. Create the "go4," insert it into the engine, and call the fireAllRules.

            ksession.insert( "go4" );
            ksession.fireAllRules();
            ---
            go4
            thing Key is in the Office
            thing Computer is in the Office
            thing Drawer is in the Office
            thing Desk is in the Office
            thing Chair is in the Office
   

   When "go4" is inserted, it returns all the previous information that is transitively below "Office."

Procedure 8.7. Creating Multiple Unbound Arguments

1. Create a query with Mulitple Unbound Arguments by implementing the following rule:

            rule "go5"
            when
              String( this == "go5" )
              isContainedIn(thing, location; )
            then
              System.out.println( "thing" + thing + "is in" + location );
            end
   

   Both thing and location are unbound out variables, and without bound arguments, everything is called upon.
2. Use the query for multiple unbound arguments.

            query isContainedIn( String x, String y )
              Location( x, y; )
              or
              ( Location( z, y; ) and isContainedIn( x, z; ) )
            end
   

3. Create the "go5," insert it into the engine, and call the fireAllRules.

            ksession.insert( "go5" );
            ksession.fireAllRules();
            ---
            go5
            thing Knife is in House
            thing Cheese is in House
            thing Key is in House
            thing Computer is in House
            thing Drawer is in House
            thing Desk is in House
            thing Chair is in House
            thing Key is in Office
            thing Computer is in Office
            thing Drawer is in Office
            thing Key is in Desk
            thing Office is in House
            thing Computer is in Desk
            thing Knife is in Kitchen
            thing Cheese is in Kitchen
            thing Kitchen is in House
            thing Key is in Drawer
            thing Drawer is in Desk
            thing Desk is in Office
            thing Chair is in Office
   

   When "go5" is called, it returns everything within everything.

Procedure 8.8. Task

1. Start a StatefulKnowledgeSession.
2. Use the following code to register the calendar:

   ksession.getCalendars().set( "weekday", weekDayCal );

3. If you wish to utilize the calendar and a timer together, use the following code:

   rule "weekdays are high priority"
      calendars "weekday"
      timer (int:0 1h)
   when 
       Alarm()
   then
       send( "priority high - we have an alarm” );
   end 
   
   rule "weekend are low priority"
      calendars "weekend"
      timer (int:0 4h)
   when 
       Alarm()
   then
       send( "priority low - we have an alarm” );
   end

Procedure 8.9. Task

1. Observe the example below:

   public int getAge() {
       Date now = DateUtil.now(); // Do NOT do this
       return DateUtil.differenceInYears(now, birthday);
   }

2. To solve this, insert a fact that wraps the current date into working memory and update that fact between fireAllRules as needed.

Procedure 9.1. Task

1. Extract the runtime jar files located in the jboss-brms-engine.zip archive of the JBoss BRMS Generic Deployable zip archive (not the EAP6 deployable zip archive) available from Red Hat Customer Portal.
2. From the JBoss Developer Studio menu, go to Window → Preferences.
   The Preferences dialog opens displaying all your preferences.
3. Navigate to Drools → Installed Drools runtimes.
4. To define a new Drools runtime, click the add button.
   The Drools Runtime dialog opens.
5. In the Drools Runtime dialog, you have the following options to provide the name for your runtime and the its location on your file system:
   • Use the default JAR files included in the Drools Eclipse plug-in to create a new Drools runtime automatically:
     1. Click the Create a new Drools c runtime ... button.
     2. Browse and select the folder on your file system where you would like this runtime to be created.
        The plug-in automatically copies all required dependencies to the specified folder.
   • Use one specific release of the Drools project,
     1. Create a folder on your file system and copy all the necessary Drools libraries and dependencies into it.
     2. Provide a name for your runtime in the Drools Runtime dialog in the Name field and browse to the location of this folder containing all the required JARs in the Path field.
6. Click OK.
   The runtime appears in your table of installed Drools runtimes.
7. Click the checkbox in front of the newly created runtime to make it the default Drools runtime.
   This default Drools runtime will be used as the runtime of all your Drools project that does not have a project-specific runtime selected.
8. Restart JBoss Developer Studio if you have changed the default runtime to ensure that all the projects that are using the default runtime update their classpath accordingly.

Procedure 9.2. Task

1. Create a new Drools project and in the final step of the New Drools Project wizard and uncheck the Use default Drools runtime checkbox.
2. Click the Configure workspace settings ... link.
   The workspace preferences showing the currently installed Drools runtimes opens.
3. Click Add to add new runtimes.

Procedure 9.3. Task

1. In the Drools perspective, right-click the project and select Properties.
   The project properties dialog opens.
2. Navigate and select the Drools category.
3. Check the Enable project specific settings checkbox and select the appropriate runtime from the drop-down box.
   If you click the Configure workspace settings ... link, the workspace preferences showing the currently installed Drools runtimes opens. You can add new runtimes there if required. If you uncheck the Enable project specific settings checkbox, it uses the default runtime as defined in your global preferences.
4. Click OK.

Procedure 9.4. Configure the Server

1. Open the Drools view by selecting Window → Open Perspective → Other and select Drools and click OK.
2. Add the server view by selecting Window → Show View → Other... and select Server → Servers.
3. Open the server menu by right clicking the Servers panel and select New → Server.
4. Define the server by selecting JBoss Enterprise Middleware → JBoss Enterprise Application Platform 6.1+ and clicking Next.
5. Set the home directory by clicking the Browse button. Navigate to and select the installation directory for JBoss EAP which has JBoss BRMS installed.
6. Provide a name for the server in the Name field, ensure that the configuration file is set, and click Finish.

1. To create breakpoints in the Package Explorer view or Navigator view of the JBoss BRMS perspective, double-click the selected .drl file to open it in the editor.
2. You can add and remove rule breakpoints in the .drl files in two ways:
   • Double-click the rule in the Rule editor at the line where you want to add a breakpoint. A breakpoint can be removed by double-clicking the rule once more.

     Note

     Rule breakpoints can only be created in the consequence of a rule. Double-clicking on a line where no breakpoint is allowed does nothing.
   • Right-click the ruler. Select the Toggle Breakpoint action in the context menu. Choosing this action adds a breakpoint at the selected line or remove it if there is one already.
3. The Debug perspective contains a Breakpoints view which can be used to see all defined breakpoints, get their properties, enable/disable and remove them. You can switch to it by clicking Window → Perspective → Others → Debug .