Chapter 6. Integrating Rules

6.1. The Knowledge Agent

The Knowledge Agent is a component which is embedded in the knowledge API. No additional components are required to use the Knowledge Agent. If you are using the JBoss Enterprise BRMS Platform, the application only needs to include the drools-core dependencies in its classpath, i.e. the drools and mvel JARs.
Rules that have been compiled in packages are ready to use in the target application.
The Following example constructs an agent that will build a new KnowledgeBase from the files specified in the path String. It will pull those files every 60 seconds, which is the default, to see if they are updated. If new files are found, it will construct a new KnowledgeBase. If the change set specifies a resource that is a directory, its contents will be scanned for changes too. 
KnowledgeAgent kagent = KnowledgeAgentFactory.newKnowledgeAgent( "MyAgent" );
kagent.applyChangeSet( ResourceFactory.newUrlResource( url ) );
KnowledgeBase kbase = kagent.getKnowledgeBase();
The KnowledgeAgent can accept a configuration that allows for some of the defaults to be changed. An example property is "drools.agent.scanDirectories;" by default, any specified directories are scanned for new additions. 
KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();

KnowledgeAgentConfiguration kaconf = KnowledgeAgentFactory.newKnowledgeAgentConfiguration();
kaconf.setProperty( "drools.agent.scanDirectories", "false" ); // we don't scan directories, only files
       
KnowledgeAgent kagent = KnowledgeAgentFactory.newKnowledgeAgent( "test agent", kaconf );
// resource to the change-set xml for the resources to add
kagent.applyChangeSet( ResourceFactory.newUrlResource( url ) );
This is an example of the change-set.xml file. 
<change-set xmlns='http://drools.org/drools-5.0/change-set'";
    xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
    xs:schemaLocation='http://drools.org/drools-5.0/change-set drools-change-set-5.0.xsd' >
    <add>
        <resource source='http://localhost:9000/TEST.pkg' type='PKG' />
    </add> 
</change-set>
Resource scanning is enabled by default. It is a service and must be started. This can be done via the ResourceFactory. 
ResourceFactory.getResourceChangeNotifierService().start();
ResourceFactory.getResourceChangeScannerService().start();