6.4.2. Embedding an executable rule model in a Java application

Procedure

1. Add the following dependencies to the relevant classpath for your Java project:

   • drools-canonical-model: Enables an executable canonical representation of a rule set model that is independent from Red Hat Decision Manager
   • drools-model-compiler: Compiles the executable model into Red Hat Decision Manager internal data structures so that it can be executed by the decision engine

   <dependency>
     <groupId>org.drools</groupId>
     <artifactId>drools-canonical-model</artifactId>
     <version>${rhdm.version}</version>
   </dependency>
   
   <dependency>
     <groupId>org.drools</groupId>
     <artifactId>drools-model-compiler</artifactId>
     <version>${rhdm.version}</version>
   </dependency>

   The <version> is the Maven artifact version for Red Hat Decision Manager currently used in your project (for example, 7.18.0.Final-redhat-00002).

   注記

   Instead of specifying a Red Hat Decision Manager <version> for individual dependencies, consider adding the Red Hat Business Automation bill of materials (BOM) dependency to your project pom.xml file. The Red Hat Business Automation BOM applies to both Red Hat Decision Manager and Red Hat Process Automation Manager. When you add the BOM files, the correct versions of transitive dependencies from the provided Maven repositories are included in the project.

   Example BOM dependency:

   <dependency>
     <groupId>com.redhat.ba</groupId>
     <artifactId>ba-platform-bom</artifactId>
     <version>7.3.0.GA-redhat-00002</version>
     <scope>import</scope>
     <type>pom</type>
   </dependency>

   For more information about the Red Hat Business Automation BOM, see What is the mapping between RHDM product and maven library version?.

2. Add rule assets to the KIE virtual file system KieFileSystem and use KieBuilder with buildAll( ExecutableModelProject.class ) specified to build the assets from an executable model:

   import org.kie.api.KieServices;
   import org.kie.api.builder.KieFileSystem;
   import org.kie.api.builder.KieBuilder;
   
     KieServices ks = KieServices.Factory.get();
     KieFileSystem kfs = ks.newKieFileSystem()
     kfs.write("src/main/resources/KBase1/ruleSet1.drl", stringContainingAValidDRL)
     .write("src/main/resources/dtable.xls",
       kieServices.getResources().newInputStreamResource(dtableFileStream));
   
     KieBuilder kieBuilder = ks.newKieBuilder( kfs );
     // Build from an executable model
     kieBuilder.buildAll( ExecutableModelProject.class )
     assertEquals(0, kieBuilder.getResults().getMessages(Message.Level.ERROR).size());

   After KieFileSystem is built from the executable model, the resulting KieSession uses constraints based on lambda expressions instead of less-efficient mvel expressions. If buildAll() contains no arguments, the project is built in the standard method without an executable model.

   As a more manual alternative to using KieFileSystem for creating executable models, you can define a Model with a fluent API and create a KieBase from it:

   Model model = new ModelImpl().addRule( rule );
   KieBase kieBase = KieBaseBuilder.createKieBaseFromModel( model );