Page History

...

The ServiceMix Drools component provides JBI integration to the Drools Rules Engine.

This Service Engine It can be used to deploy a rules set that will implement a router or an actual service.

...

This component can also be used to implement a real service, as shown in the Fibonnacci example. The service can act as a consumer and create / send exchanges by using the client provided by the jbi helper.

Maven Archetype

You can create a Drools Service Unit using the servicemix-drools-service-unit Maven archetype:

mvn archetype:create \
  -DarchetypeGroupId=org.apache.servicemix.tooling \
  -DarchetypeArtifactId=servicemix-drools-service-unit \
  -DarchetypeVersion=2010.01 \
  -DgroupId=your.group.id \
  -DartifactId=your.artifact.

...

id \
  -Dversion=your-version

Once you've customized the service unit, simply install the SU:

mvn install

<dependency>
  <groupId>your.group.id</groupId>
  <artifactId>your.artifact.id</artifactId>
  <version>your-version</version>
</dependency>

Endpoint Configuration

<beans xmlns:drools="http://servicemix.apache.org/drools/1.0"
       xmlns:replaceMe="http://servicemix.apache.org/replaceMe">

  <drools:endpoint service="replaceMe:serviceName" endpoint="drools"
    ruleBaseResource="classpath:router.drl"
    namespaceContext="#nsContext"/>

  <drools:namespace-context id="nsContext">
    <drools:namespaces>
      <drools:namespace prefix="bar">http://servicemix.apache.org/bar</drools:namespace>
    </drools:namespaces>
  </drools:namespace-context>

</beans>

JBI Helper

Note that this component is only available in releases >= 3.1 and deprecate the older lightweight Drools component

...

DRL files deployed to the servicemix-drools engine have access to a JbiHelper class in a global variable named jbi which provides the following attributes and methods:

...

The received exchange is added as a fact to the working memory.
Note that, due to Drools limited support for non simple java beans accessors, the JBI MessageExchange and NormalizedMessage are wrapped with simple beans.

Injecting additional beans in the rules

The JbiHelper is injected by the component itself so that you can access the current exchange and handle it. However, there are cases where you need to add your own beans and inject them in the rules definition. Starting from ServiceMix 3.2, this is now possible using the following syntax:

<drools:endpoint  service="test:service"
                  endpoint="endpoint"
                  ruleBaseResource="classpath:router.drl"
                  globals="#globals" />
<util:map id="globals">
  <entry key="helper" value-ref="helper" />
</util:map>
<bean id="helper" class="org.example.Helper" />

In the rules definition, just add:

global org.example.Helper helper;

xmlns:util="http://www.springframework.org/schema/util"

Then you can use it from your rules ...

Router

<drools:endpoint  service="test:service"
                  endpoint="endpoint"
                  ruleBaseResource="classpath:router.drl" />

...