I have included a reference to "expander" in my DRL. The files look as follows: (src/main/rules/mylang.dsl) [consequence][]Log "{msg}"=System.out.println("{msg}"); (src/main/rules/Sample.drl) package com.sample expander mylang.dsl import com.sample.DroolsTest.Message; rule "Hello World" when m : Message( status == Message.HELLO, message : message ) then System.out.println( message ); m.setMessage( "Goodbye cruel world" ); m.setStatus( Message.GOODBYE ); update( m ); end rule "GoodBye" no-loop true when m : Message( status == Message.GOODBYE, message : message ) then System.out.println( message ); m.setMessage( message ); end (src/main/java/DroolsTest.java) package com.sample; import java.io.InputStreamReader; import java.io.Reader; import org.drools.RuleBase; import org.drools.RuleBaseFactory; import org.drools.WorkingMemory; import org.drools.compiler.PackageBuilder; import org.drools.rule.Package; /** * This is a sample file to launch a rule package from a rule source file. */ public class DroolsTest { public static final void main(String[] args) { try { //load up the rulebase RuleBase ruleBase = readRule(); WorkingMemory workingMemory = ruleBase.newStatefulSession(); //go ! Message message = new Message(); message.setMessage( "Hello World" ); message.setStatus( Message.HELLO ); workingMemory.insert( message ); workingMemory.fireAllRules(); } catch (Throwable t) { t.printStackTrace(); } } /** * Please note that this is the "low level" rule assembly API. */ private static RuleBase readRule() throws Exception { //read in the source Reader source = new InputStreamReader( DroolsTest.class.getResourceAsStream( "/Sample.drl" ) ); //optionally read in the DSL (if you are using it). Reader dsl = new InputStreamReader( DroolsTest.class.getResourceAsStream( "/mylang.dsl" ) ); //Use package builder to build up a rule package. //An alternative lower level class called "DrlParser" can also be used... PackageBuilder builder = new PackageBuilder(); //this wil parse and compile in one step //NOTE: There are 2 methods here, the one argument one is for normal DRL. //builder.addPackageFromDrl( source ); //Use the following instead of above if you are using a DSL: builder.addPackageFromDrl( source, dsl ); //get the compiled package (which is serializable) Package pkg = builder.getPackage(); //add the package to a rulebase (deploy the rule package). RuleBase ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage( pkg ); return ruleBase; } public static class Message { public static final int HELLO = 0; public static final int GOODBYE = 1; private String message; private int status; public String getMessage() { return this.message; } public void setMessage(String message) { this.message = message; } public int getStatus() { return this.status; } public void setStatus( int status ) { this.status = status; } } } Anstis, Michael (M.) wrote: -- View this message in context: http://www.nabble.com/Problem-with-DSL-in-Drools-4.0.3-tf4722439.html#a13... Sent from the drools - user mailing list archive at Nabble.com.

I finally figured out the problem. I didn't know that you couldn't mix mvel and a DSL in a rule. So by following those 8 steps, essentially that's what was happening. tansey wrote: -- View this message in context: http://www.nabble.com/Problem-with-DSL-in-Drools-4.0.3-tf4722439.html#a13... Sent from the drools - user mailing list archive at Nabble.com.