[rules-users] Getting hold of the Evaluator Registry
Edson Tirelli
tirelli at post.com
Wed Jul 15 09:57:02 EDT 2009
Yes, you are in the right track, and I understand this is a bit confusing
at first. One more reason for people to go to the October Rules Fest 2009
where I will give a presentation on all the ways to extend the engine to
solve specific problems. It will be interesting I hope (last year was
awesome) and even Charles Forgy will be there doing a presentation on
Parallel Rete. :)
Meanwhile I will write a tutorial on this, but just to help you there,
your approach is correct, except that you don't need to setup the option for
each operator. It works like this:
* One EvaluatorDefinition class implements support to one or more
evaluators, defined by the method public String[] getEvaluatorIds().
* All you need to do, then, is wire you class once and the engine will
pick-up all the IDs supported by that class. When you have your class wired,
you give it a unique string identifier, so that if you ever need to replace
it, or remove it, you will use that id. Sometimes we use the operator as the
ID, but usually it is something that reminds you of the kind of evaluators
that class define. For instance, drools registers the
ComparableEvaluatorsDefinition in this way:
drools.evaluator.comparable =
org.drools.base.evaluators.ComparableEvaluatorsDefinition
So in this case, "comparable" is the identifier. Finally, from my previous
e-mail you will see that the reason that the eclipse IDE is still giving you
errors is that you are using the API to configure the evaluators. Just move
the configuration to the configuration file and the IDE will pick it up.
[]s
Edson
2009/7/15 Asif Iqbal <Asif.Iqbal at infor.com>
> Edson,
>
>
>
> What I have done so far is created a CustomComparableEvaluatorsDefinition,
> which is exactly the same as the default ComparableEvaluatorsDefinition
> apart form having support for strings, which I have done by creating
> StringGreaterOrEqualEvaluators and added that in my custom class, using the
> addEvaluatorFunction :-
>
>
>
> addEvaluator( ValueType.SHORT_TYPE,
> Operator.GREATER, ShortGreaterEvaluator.INSTANCE );
>
> addEvaluator( ValueType.SHORT_TYPE,
> Operator.GREATER_OR_EQUAL, ShortGreaterOrEqualEvaluator.INSTANCE );
>
> addEvaluator( ValueType.PSHORT_TYPE,
> Operator.LESS, ShortLessEvaluator.INSTANCE );
>
> addEvaluator( ValueType.PSHORT_TYPE,
> Operator.LESS_OR_EQUAL, ShortLessOrEqualEvaluator.INSTANCE );
>
> addEvaluator( ValueType.PSHORT_TYPE,
> Operator.GREATER, ShortGreaterEvaluator.INSTANCE );
>
> addEvaluator( ValueType.PSHORT_TYPE,
> Operator.GREATER_OR_EQUAL, ShortGreaterOrEqualEvaluator.INSTANCE );
>
> //Custom additions
>
> addEvaluator( ValueType.STRING_TYPE,
> Operator.LESS, StringLessEvaluator.INSTANCE );
>
> addEvaluator( ValueType.STRING_TYPE,
> Operator.LESS_OR_EQUAL, StringLessOrEqualEvaluator.INSTANCE );
>
> addEvaluator( ValueType.STRING_TYPE,
> Operator.GREATER, StringGreaterEvaluator.INSTANCE );
>
> addEvaluator( ValueType.STRING_TYPE,
> Operator.GREATER_OR_EQUAL, StringGreaterOrEqualEvaluator.INSTANCE );
>
>
>
> Now Im am trying to wire it, with the following..
>
>
>
> CustomComparableEvaluatorsDefinition
> MyCustomComparable custom = *new* CustomComparableEvaluatorsDefinition();
>
> KnowledgeBuilderConfiguration config =
> KnowledgeBuilderFactory.*newKnowledgeBuilderConfiguration*();
>
> EvaluatorOption option = EvaluatorOption.*get*(*
> Operator.LESS.toString()*, custom);
>
> EvaluatorOption option2 = EvaluatorOption.*get*(*
> Operator.LESS_OR_EQUAL.toString()*, custom);
>
> EvaluatorOption option3 = EvaluatorOption.*get*(*
> Operator.GREATER.toString()*, custom);
>
> EvaluatorOption option4 = EvaluatorOption.*get*(*
> Operator.GREATER_OR_EQUAL.toString()*, custom);
>
>
>
> config.setOption(option);
>
> config.setOption(option2);
>
> config.setOption(option3);
>
> config.setOption(option4);
>
>
>
> Firstly is this the correct approach?....
>
>
>
> The problem im having is that in my drl files still flag errors, when I do
> “test” > “test2” , am I missing something?
>
>
>
> Regards
>
>
> ------------------------------
>
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Asif Iqbal
> *Sent:* 15 July 2009 08:20
> *To:* Rules Users List
> *Subject:* RE: [rules-users] Getting hold of the Evaluator Registry
>
>
>
> Edson,
>
>
>
> Thanks for your replies they have really helped.
>
>
>
> 1) I am still not sure about creating a new operator, since the ‘>=’
> operator already exists it just does not cater for strings, which I want to
> add. So would creating a new operator cause the existing one to be
> overrriden when added to the registry?
>
>
>
> 2) Having looked at the examples and tests you emailed, I am still
> unsure how to actually wire in the changes, say for example I have replaced
> the existing ‘>=’ evaluator or created a new evaluator so that ‘>=’ now
> handles strings. When writing rules will the engine pick this up?.. or do I
> need to create a new jar by building?.. or do I need to update a
> configuration file?... im just not sure…
>
>
>
> 3) Wouldn’t the following also add the evaluator definition by
> replacing the existing one..
>
>
>
> *PackageBuilderConfiguration* pkgb = *new**PackageBuilderConfiguration()
> *;
>
> *pkgb.getEvaluatorRegistry()*.*addEvaluatorDefinition*(*new
> *ComparableEvaluatorsDefinition());
>
> *PackageBuilder* builder = *new** PackageBuilder(pkgb)*;
>
>
>
> *builder.addPackageFromDrl(source)*;
>
> *Package* pkg = *builder.getPackage()*;
>
> // Add the package to a *rulebase* (deploy the rule
> package).
>
> rules = *RuleBaseFactory.newRuleBase()*;
>
> *rules**.addPackage(pkg)*;
>
>
>
> Thanks for your help…
>
>
> ------------------------------
>
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Edson Tirelli
> *Sent:* 14 July 2009 23:05
> *To:* Rules Users List
> *Subject:* Re: [rules-users] Getting hold of the Evaluator Registry
>
>
>
>
> I am working in one example of drools features where I implement a
> custom evaluator here:
>
>
> http://anonsvn.jboss.org/repos/labs/labs/jbossrules/contrib/lotrc/src/main/java/org/drools/examples/lotrc/evaluators/IsAdjacentToEvaluatorDefinition.java
>
> I use the configuration file instead of API in the example:
>
>
> http://anonsvn.jboss.org/repos/labs/labs/jbossrules/contrib/lotrc/src/main/resources/META-INF/drools.packagebuilder.conf
>
> []s
> Edson
>
> 2009/7/14 Edson Tirelli <tirelli at post.com>
>
>
> Asif,
>
> My recommendation is create a new operator for you instead of overriding
> existing ones. Although if you really want to replace the existing ones,
> setting the property or calling the API to register a new operator will
> override the default.
>
> See:
>
>
> http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-compiler/src/test/java/org/drools/builder/KnowledgeBuilderConfigurationTest.java
>
> Test method:
>
> testEvaluatorConfiguration()
>
> []s
> Edson
>
> 2009/7/14 Asif Iqbal <Asif.Iqbal at infor.com>
>
> Hi,
>
>
>
> What I need to do is modify one of the evaluator classes specifically ‘<=’,
> so that it can handle strings. Now I know I need to create a class similar
> to ComparableEvaluatorDefinition. But what I want to do is replace the
> existing one in the evaluator registry with my implementation which will
> include the additional String capability.
>
>
>
> From my understanding that should be all that is required. Unless im
> missing something… now all I need to know is how do I get hold of the
> evaluator registry?
>
>
>
> Cheers
>
>
>
> I
>
>
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
>
>
> --
> Edson Tirelli
> JBoss Drools Core Development
> JBoss by Red Hat @ www.jboss.com
>
>
>
>
> --
> Edson Tirelli
> JBoss Drools Core Development
> JBoss by Red Hat @ www.jboss.com
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
--
Edson Tirelli
JBoss Drools Core Development
JBoss by Red Hat @ www.jboss.com
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