All,
Find in the following link, the documentation that is being built
for drools 3.
http://labs.jboss.com/portal/jbossrules/docs
On a quick explanation, the new syntax would be:
------------
rule "name"
ATTRIBUTES
when
LHS
then
RHS
end
------------
ATTRIBUTES: those are rule attributes like salience, duration, etc, in a
similar way Drools 2.x uses.
LHS: this is the left hand side of the rule. This is the previous
"parameter" + "condition" statements. (see bellow)
RHS: this is the right hand side of the rule. This is the consequence,
the same way in drools 2.
I think the simple way to explain LHS is to make a conversion example:
<rule name="First Rule">
<parameter identifier="objA">
<class>ClassA</class>
</parameter>
<parameter identifier="objB">
<class>ClassB</class>
</parameter>
<java:condition> objA.getStringAttr().equals("xyz") </java:condition>
<java:condition> objB.getIntAttr() > 50 </java:condition>
<java:consequence>
// some java code
</java:consequence>
</rule>
The above rule when converted to Drools 3 would became:
rule "First Rule"
when
ClassA( stringAttr == "xyz" )
ClassB( intAttr > 50 )
then
// do some java code
end
If you need a reference to the actual object matched in each "column"
(more or less what Drools 2 call parameter), you can bind it in the
following way:
rule "First Rule"
when
objA : ClassA( stringAttr == "xyz" )
objB : ClassB( intAttr > 50 )
then
// do some java code
System.out.println(objA);
System.out.println(objB);
end
In the documentation you will find syntax diagrams that can help you
understand all possible syntaxes and all the new operators/features
drools 3 has.
[]s
Edson
Ronald van Kuijk wrote:
AINAE, but it could be as simple as 'replacing' condition with when and
consequence with then, but I'll let the experts tell me.
Ronald
2006/4/13, Dmitry Goldenberg <[EMAIL PROTECTED]>:
I don't understand the relationship between the XML-based DRL notation and
this new lingo with "when" / "then".
With the DRL notation, my understanding is that you write an XML structure
like the one I'm including below. How does this change with the when/then
notation? Thanks.
<?xml version="1.0"?>
<rule-set name="SamplePolicyRuleSet"
xmlns="http://drools.org/rules";
xmlns:java="http://drools.org/semantics/java";
xmlns:xs="http://www.w3.org/2001/XMLSchema-instance";
xs:schemaLocation="http://drools.org/rules rules.xsd
http://drools.org/semantics/java java.xsd">
<!-- Imports -->
<java:import>java.lang.Object</java:import>
<java:import>java.lang.String</java:import>
<!-- Utility functions -->
<java:functions>
public boolean f1(com.weblayers.platform.rule.PolicyExecContextcontext)
{
return ...;
}
public boolean f2(com.weblayers.platform.rule.PolicyExecContextcontext)
{
return ...;
}
</java:functions>
<!-First Rule: IF (P1 AND P2) THEN RETURN OK -->
<rule name="First Rule">
<!-- Rule parameters -->
<parameter identifier="context">
<class>MyContext</class>
</parameter>
<!-- Rule Conditions -->
<java:condition>
f1() && f2()
</java:condition>
<!-- Rule Consequences -->
<java:consequence>
context.setReturn(Constants.OK);
</java:consequence>
</rule>
<!-Second Rule: IF (!(P1 AND P2)) THEN RETURN FAILURE -->
<rule name="Second Rule">
<!-- Rule parameters -->
<parameter identifier="context">
<class>MyContext</class>
</parameter>
<!-- Rule Conditions -->
<java:condition>
!(f1() && f2())
</java:condition>
<!-- Rule Consequences -->
<java:consequence>
context.setVerdict(Constants.FAIL);
</java:consequence>
</rule>
</rule-set>
--
---
Edson Tirelli
Auster Solutions do Brasil
@ www.auster.com.br
+55 11 5096-2277 / +55 11 9218-4151
