11.16. Using Pre-Compiled Rule Packages

The KnowledgeAgent is a component which is embedded in the JBoss Rules 5.0 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 only. There are no other rule-specific dependencies.
Use the KnowledgeAgent for pre-compiled rules packages. These packages can be on the local file system or in a remote location (accessed via a URL). Once you have built your rules in a package in the BRMS Platform (or from the ant task), you are ready to use the agent in your target application.
The following example constructs an agent that will build a new knowledge base from the files specified in the path String. It will poll 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 it's 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, it is possible to disable this.
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 a change-set.xml.
<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, the same is for notification. This can be done via the ResourceFactory.
ResourceFactory.getResourceChangeNotifierService().start();
ResourceFactory.getResourceChangeScannerService().start();
The deployment screen of the BRMS UI provides URLs and downloads for packages. You need the Package URI's URL to include in the change-set.xml file so as to specify that you want this package. It specifies an exact version, in this case a snapshot. Each snapshot has its own URL. If you want the latest version then replace NewSnapshot with LATEST.
You can also download a package file (PKG) from the deployment screen's list of URLs. Put that file in a directory and use the file or dir feature of the KnowledgeAgent. This will automatically contact the JBoss Enterprise BRMS Platform server for updates which may not be wanted in some scenarios.