Dmitry Goldenberg wrote:
rule "First Rule"
when
ClassA( stringAttr == "xyz" )
ClassB( intAttr > 50 )
then
// do some java code
end
In this example, where is the call made to the getStringAttr() and getIntAttr() methods on instances of ClassA and ClassB ??
look at LiteralConstraint and the ASM code, we take car of this for you.
We believe this syntax to be less verbose and more declarative and
clearer than standard java notation. It is also directly from JRules.
This should make it more trivial for JRules developers to directly
convert their code.
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
Here, are objA and objB Boolean ?
No here objA is a reference to an instance of ClassA and objB is a
reference to an instance of ClassB.
________________________________
From: Edson Tirelli [mailto:[EMAIL PROTECTED]
Sent: Thu 4/13/2006 3:47 PM
To: [email protected]
Subject: Re: [drools-user] The DRL notation vs. jbossrules Rule Language - ?
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
