Question

I’m trying to run very simple application using Drools and for a couple of hours now can’t set up pom.xml with all dependencies.

Here is how it looks now:

    <dependencies>

    <!-- Drools engine -->
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-core</artifactId>
        <version>5.4.0.Final</version>
    </dependency>

    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-compiler</artifactId>
        <version>5.4.0.Final</version>
    </dependency>       

    <!-- Test -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.7</version>
        <scope>test</scope>
    </dependency>
</dependencies>

Just like in
https://community.jboss.org/wiki/DroolsMaven

But what I get:

org.drools.RuntimeDroolsException: Unable to load dialect 'org.drools.rule.builder.dialect.java.JavaDialectConfiguration:java:org.drools.rule.builder.dialect.java.JavaDialectConfiguration'
at org.drools.compiler.PackageBuilderConfiguration.addDialect(PackageBuilderConfiguration.java:313)
at org.drools.compiler.PackageBuilderConfiguration.buildDialectConfigurationMap(PackageBuilderConfiguration.java:298)
at org.drools.compiler.PackageBuilderConfiguration.init(PackageBuilderConfiguration.java:187)
at org.drools.compiler.PackageBuilderConfiguration.<init>(PackageBuilderConfiguration.java:160)
at org.drools.builder.impl.KnowledgeBuilderFactoryServiceImpl.newKnowledgeBuilderConfiguration(KnowledgeBuilderFactoryServiceImpl.java:26)
at org.drools.builder.KnowledgeBuilderFactory.newKnowledgeBuilderConfiguration(KnowledgeBuilderFactory.java:85)
yada-yada-yada

Caused by: java.lang.RuntimeException: The Janino jar is not in the classpath

If I try to add Janino I get another exception about some missing classes(I don’t think I should add Janino here anyway as it should be a dependency of something else).
Do I miss anything in my pom?

Thanks!

Leonty

Answer 1

By default, drools-compiler uses the eclipse compiler (JavaDialectConfiguration.ECLIPSE) for the java dialect which is a transitive dependency:

<dependency>
  <groupId>org.eclipse.jdt.core.compiler</groupId>
  <artifactId>ecj</artifactId>
</dependency>

However, if you prefer the janino compiler(JavaDialectConfiguration.JANINO), you need to add the janino dependency yourself because it is an optional transitive dependency:

<dependency>
  <groupId>org.codehaus.janino</groupId>
  <artifactId>janino</artifactId>
  <optional>true</optional>
</dependency>

Look at the droolsjbpm-parent pom to find out which version to use.