JUDCon São Paulo - Drools in a Nutshell

Drools
in a nutshell
Everything you always wanted to know
but didn't know whom to ask! ;)

Friday, April 19, 13

porcelli@redhat.com
no:sql(br) @porcelli

rcelli

Alexandre Porcelli
Program Committee

Alexandre Porcelli
Program Committee
Emerging Languages on the JVM

Alexandre Porcelli
Core Engineer

#guvnordev Alexandre Porcelli
#droolsdev Principal Software Engineer

#jbpmdev
#optaplanner-dev


Drools? was born as a rule engine ...
evolved as business modeling solution ...
targets as knowledge representation and reasoning platform!


opta
expert fusion guvnor
planner

jbpm jbpm
jbpm
console designer


expert guvnor


so...
what?

Logic and Data Separation

Speed and Scalability
Understandable Rules

Centralization of Knowledge

Declarative Programming


rule
what is


rule <rule_name>
<attribute><value>
when
<conditions>
then
<actions>
end


rule "Infer Adult"
when
$p : Person( age >= 18 )
then
System.out.println("Adult!");
end


patternmatching

Person( age >= 18 )
ﬁeld name restriction

object type constraint

pattern


rule "Infer Child" rule "Infer Baby"
when when
Person( age < 18 ) Person( age <= 2 )
then then
//code //code
end end

rule "Infer Adult" rule "Infer Senior"
when when
Person( age >= 18 ) Person( age >= < 60 )
then then
//code //code
end end


Person(age=10)
when when
then then
//code //code
end end

when when
then then
//code //code
end end


Person(age=22)
when when
then then
//code //code
end end

when when
then then
//code //code
end end


Person(age=61)
when when
then then
//code //code
end end

when when
then then
//code //code
end end


Person(age=1)
when when
then then
//code //code
end end

when when
then then
//code //code
end end


OtherObject()
when when
then then
//code //code
end end

when when
then then
//code //code
end end


decouple logic
rule "Infer Child" rule "Infer Adult"
when when
$p : Person( age < 18 ) $p : Person( age >= 18 )
then then
insertLogical( new IsChild( $p ) ) insertLogical( new IsAdult( $p ) )
end end

rule "Issue Child Bus Pass" rule "Issue Adult Bus Pass"
when when
$p : Person( ) $p : Person( )
IsChild( person == $p ) IsAdult( person =$p )
then then
insertLogical( new ChildBusPass( $p ) ); insertLogical( new AdultBusPass( $p ) );
end end


patternmatching
Person( $age : age )

Person( age == ( $age + 1 ) )

Person( age > 30 && < 40 || hair in ("black", "brown") )

Person( pets contains $rover )

Person( pets["rover"].type == "dog" )

Person( insurance.valid )


under the
hood

hybrid
reasoning
system


forward
backward
chainning

forwardchainning
data driven/reactionary
rule "Adults that like cheddar"
when
Cheese( $cheddar : name == "cheddar" )
$p : Person( age >= 18, favouriteCheese == $cheddar )
then
System.out.println( $p.getName() + " likes cheddar!");
end


backwardchainning
goal driven
declare Parent
declare Man declare Woman
parent : String
name : String name : String
child : String
end end
end

query man( String name )
Man( name := name )
end

query woman( String name )
Woman( name := name )
end

query parent( String parent, String child )
Parent( parent := parent, child := child )
end


backwardchainning
query father( String father, String child )
?man( father; )
?parent( father, child; )
end

query mother( String mother, String child )
?woman( mother; )
?parent( mother, child; )
end

query son( String son, String parent )
?man( son; )
?parent( parent, son; )
end

query daughter( String daughter, String parent )
?woman( daughter; )
?parent( parent, daughter; )
end


backwardforward
fewer hypotheses lot’s hypotheses
query data lot’s data upfront


rete
algorithm

reteoo
rule "Like cheddar"
when
$p : Person( favouriteCheese == $cheddar )
then
System.out.println( $p.getName() + " likes cheddar" );
end

rule "NOT Like cheddar"
when
$p : Person( favouriteCheese != $cheddar )
then
System.out.println( $p.getName() + " not like cheddar" );
end


reteoo
rete node

object type node

alpha node

left input node

join node

terminal


so...
how?

codeapi
final KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
// this will parse and compile in one step
kbuilder.add( ResourceFactory.newClassPathResource("HelloWorld.drl",
HelloWorldExample.class), ResourceType.DRL);

// Check the builder for errors
if ( kbuilder.hasErrors() ) {
throw new RuntimeException("Error compiling.");
}

// get the compiled packages (which are serializable)
final Collection<KnowledgePackage> pkgs = kbuilder.getKnowledgePackages();

// add the packages to a KnowledgeBase (deploy the knowledge packages).
final KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
kbase.addKnowledgePackages(pkgs);


codeapi
final StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
ksession.setGlobal( "myGlobalObj", globalObj );

for( Object fact : _facts_ ) {
ksession.insert( fact );
}

ksession.fireUntilHalt();

ksession.fireAllRules(); SessionEntryPoint entryPoint =
ksession.getEntryPoint( "entrypoint_name" );
ksession.dispose();
entryPoint.insert( _fact_ );


codeapi
final StatelessKnowledgeSession ksession = kbase.newStatelessKnowledgeSession();

ksession.execute( _facts_ );


please
one sec!

new
paradigm?

yes you can construct
your systems using
almost only rules!


pong
demo

no
you can adapt your
existing systems
(few lines) to take
advantage of drools


public void aprovarPagamento(String apoliceId, String sinistroId,
" " int valor, String cpfAprovador) {

" if (!existeReserva(sinistroId)) {
" " throw new IllegalStateException(
" " " " "não existe reserva para o sinistro.");
" }

" Pessoa aprovador = pessoaService.buscarPessoa(cpfAprovador);
" if (aprovador.getPapeis()
" " " .contains(Pessoa.Papeis.COORDENADOR_SEGURADORA)
" " " || aprovador.getPapeis().contains(
" " " " " Pessoa.Papeis.GERENTE_SEGURADORA)
" " " || aprovador.getPapeis().contains(
" " " " " Pessoa.Papeis.DIRETOR_SEGURADORA)
" " " || aprovador.getPapeis().contains(Pessoa.Papeis.VP_SEGURADORA)) {
" " if (valor <= 5000) {
" " " pagar(apoliceId, sinistroId, valor);
" " } else if (valor > 500000) {
" " " if (aprovador.getPapeis().contains(Pessoa.Papeis.VP_SEGURADORA)) {
" " " " pagar(apoliceId, sinistroId, valor);
" " " } else {
" " " " throw new IllegalStateException(
" " " " " " "Aprovador não tem alçada para aprovação.");
" " " }
" " } else if (valor <= 10000) {
" " " if (aprovador.getPapeis().contains(
" " " " " Pessoa.Papeis.GERENTE_SEGURADORA)
" " " " " || aprovador.getPapeis().contains(
" " " " " " " Pessoa.Papeis.DIRETOR_SEGURADORA)
" " " " " " " Pessoa.Papeis.VP_SEGURADORA)) {
" " " } else {
" " " }
" " } else if (valor <= 500000) {
" " " if (aprovador.getPapeis().contains(
" " " " " Pessoa.Papeis.DIRETOR_SEGURADORA)
" " " " " " " Pessoa.Papeis.VP_SEGURADORA)) {
" " " } else {
" " " }
" " } else {
" " " throw new IllegalStateException("Problemas na aprovação.");
" " }
" } else {
" " throw new IllegalStateException(
" " " " "Aprovador não é funcionário da seguradora.");
" }
}


system

control flow control flow control flow
business rules business rules business rules




public void aprovarPagamento( String apoliceId,
String sinistroId,
int valor,
String cpfAprovador ) {
if ( !existeReserva( sinistroId ) ) {
throw new IllegalStateException(
"Não existe reserva para o sinistro." );
}

final Pessoa aprovador = pessoaService.buscarPessoa( cpfAprovador );

final ValorPagamentoApolice pagamento = new ValorPagamentoApolice( ... );

ksession.execute( asList( aprovador, pagamento ) );
if ( !pagamento.isPago() ) {
throw new IllegalArgumentException( "Pagamento nao efetuado." );
}
}


rule "Coordenador tentando fraudar"
" when
" " p: Pessoa ( papeis contains Pessoa.Papeis.COORDENADOR_SEGURADORA )
" " v: ValorPagamentoApolice( valor > 50000 )
" " f: FinanceiroService( )
" then
" System.out.println("O coordenador tentou fazer um pagamento não autorizado");
" " retract( f );
end
rule "VP"
" when
" " m : Pessoa( papeis contains Pessoa.Papeis.VP_SEGURADORA )
" " v: ValorPagamentoApolice( valor > 500000 )
" then
" executar(f, v);
" " retract( f );
end

rule "Nenhum funcionario pode aprovar sua apolice"
salience 8888
" when
" " p : Pessoa( $cpfPessoa: cpf )
" " v: ValorPagamentoApolice( cpfSefurado == $cpfPessoa, valor >= 50000 )
" then
" System.out.println("O profissional tentou aprovar sua apolice.");
" retract( f );
rule "Diretor ou VP" end
" when
" " m : Pessoa( papeis contains Pessoa.Papeis.DIRETOR_SEGURADORA ||
" " " " " papeis contains Pessoa.Papeis.VP_SEGURADORA )
" " v: ValorPagamentoApolice( valor > 10000 && <= 500000 )
" then
" executar(f, v);
" " retract( f );
end


system

control flow control flow control flow business rules
business rules
business rules
business rules business rules
business rules
business rules
guvnor


business analyst
write rules?

no
they won’t do this:
rule "NOT Like cheddar"
when
$p : Person( favouriteCheese != $cheddar )
then
System.out.println( $p.getName() + " not like cheddar" );
end

technical rule


yes
but they can do this:

decision table


yes
and this

test scenario


so...
next?

retewilldie
http://blog.athico.com/2013/01/life-beyond-rete-rip-rete-2013.html

phreak

maven
compatible
project structure

kjar

KieServices ks = KieServices.Factory.get();
KieContainer kContainer = ks.getKieClasspathContainer();
KieSession kSession = kContainer.newKieSession("ksession2");
kSession.setGlobal("out", out);

kSession.insert(new Message("Dave", "Hello, HAL. Do you read me, HAL?"));
kSession.fireAllRules();

newapi
java code

public class KProject {

@Inject @KBase("fol4.test1.KBase1")
KnowledgeBase kBase1;

public KnowledgeBase getKBase1() {
return kBase1;
}

@Inject @KBase("fol4.test2.KBase2")
KnowledgeBase kBase2;

public KnowledgeBase getKBase2() {
return kBase2;
}

@Inject @KSession("fol4.test1.KSession1")
StatelessKnowledgeSession kBase1kSession1;

cdi
public StatelessKnowledgeSession getKBase1KSession1() {
return kBase1kSession1;
}

@Inject @KSession("fol4.test1.KSession2")
StatefulKnowledgeSession kBase1kSession2;

public StatefulKnowledgeSession getKBase1KSession2() {
return kBase1kSession2;
}
}

java code


<?xml version="1.0" encoding="UTF-8"?>
<kmodule
xmlns="http://jboss.org/kie/6.0.0/kmodule">

<kbase name="cdiexample">
<ksession name="ksession1"/>
</kbase>

</kmodule>

meta-inf/kmodule.xml

<?xml version="1.0" encoding="UTF-8"?>
<kmodule

cdi
xmlns="http://jboss.org/kie/6.0.0/kmodule">

<kbase name="cdiexamplewithinclusion" includes="cdiexample">
<ksession name="ksession2"/>
</kbase>

</kmodule>

inclusion (pom.xml dependency)


errai gwt
cdi best-practices
jee java
scalability dev tools (ide)
(template) html legacy

uberfire

database

+git

shameless self promotion

building world class
web consoles using
uberfire auditorium 4
saturday, april 20th


that’s
all folks!

questions?

thanks!
porcelli@redhat.com
@porcelli
#guvnordev
#droolsdev
#jbpmdev
Alexandre Porcelli
#optaplanner-dev
Principal Software Engineer


JUDCon São Paulo - Drools in a Nutshell

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JUDCon São Paulo - Drools in a Nutshell