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How and why I turned my old Java projects into a first-class serverless component

Mario Fusco, profile picture
Mario Fusco

Mario Fusco discusses turning old Java rule engine projects into serverless components by refactoring them to run natively on GraalVM and integrate with Quarkus. He describes the limitations of ahead-of-time compilation with GraalVM, such as lack of dynamic classloading. He details refactoring Drools to use an executable model and removing dependencies on dynamic class definition. This allows Drools to natively compile on GraalVM. He also discusses integrating the refactored Drools with Quarkus.

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How and why I turned my old Java projects into a first-class serverless component by Mario Fusco Red Hat – Principal Software Engineer @mariofusco c
Agenda ➱ Declarative vs. Imperative programming ➱ What is a rule engine and how it works ➱ A simple example ➱ From drl to Java: the executable model
Agenda ➱ Declarative vs. Imperative programming ➱ What is a rule engine and how it works ➱ A simple example ➱ From drl to Java: the executable model ➱ What is GraalVM ➱ AoT compilation ➱ Limitations ➱ Refactoring Drools to (natively) compile on GraalVM
Agenda c ➱ Declarative vs. Imperative programming ➱ What is a rule engine and how it works ➱ A simple example ➱ From drl to Java: the executable model ➱ What is GraalVM ➱ AoT compilation ➱ Limitations ➱ Refactoring Drools to (natively) compile on GraalVM ➱ What is Quarkus ➱ Quarkus features ➱ Integrating Drools with Quarkus ➱ Writing a Quarkus extension for Drools
What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions
What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions Declarative (What to do) Imperative (How to do it) Vs. public void helloMark(Person person) { if ( person.getName().equals( “Mark” ) { System.out.println( “Hello Mark” ); } } rule “Hello Mark” when Person( name == “Mark” ) then System.out.println( “Hello Mark” ); end
What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions Declarative (What to do) Imperative (How to do it) Vs. public void helloMark(Person person) { if ( person.getName().equals( “Mark” ) { System.out.println( “Hello Mark” ); } } rule “Hello Mark” when Person( name == “Mark” ) then System.out.println( “Hello Mark” ); end A method must be called directly Rules can never be called directly
What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions Declarative (What to do) Imperative (How to do it) Vs. public void helloMark(Person person) { if ( person.getName().equals( “Mark” ) { System.out.println( “Hello Mark” ); } } rule “Hello Mark” when Person( name == “Mark” ) then System.out.println( “Hello Mark” ); end A method must be called directly Specific passing of arguments Rules can never be called directly Specific instances cannot be passed but are automatically selected with pattern-matching
Introducing ➱ Easier to understand → Requirements can be more naturally translated into rules. It is more likely for a technically skilled business analyst to verify, validate or even change a rule than a piece of Java code ➱ Improved maintainability → We don't care about how to implement a solution only what needs to be done to solve a problem ➱ Deals with evolving complexity → It's easier to modify a rule than a Java program and to determine the impact of this change on the rest of the application ➱ Modularity → Each rule models an isolated and small portion of your business logic and is not part of a monolithic program ➱ Clear separation of business logic from the rest of the system → Business and infrastructural code have very different lifecycles ➱ Complex Event Processing → Facts can be handled like timestamped events allowing temporal reasoning on them RULES
How a rule-based system works ➱ The Rule Base contains a computation efficient representation of the set of the defined rules ➱ The Working Memory contains the set of facts inserted into sessions ➱ The engine matches the fact in the working memory against the rules set ➱ When a match is found it creates an activation and put it into the agenda ➱ An activation is the tuple of facts matching the conditions of a rule plus the rule itself ➱ When all activations have been created the agenda elects through a conflict resolution strategy the one to be executed ➱ The elected activation is passed to the execution engine and the fired
A simple rule set rule RaiseAlarm when exists Fire() then insert( new Alarm( "house1" ) ); System.out.println( "Raise the Alarm"); end rule CancelAlarm when not Fire() a : Alarm() then delete( a ); System.out.println( "Cancel the Alarm"); end rule TurnSprinklerOn when s : Sprinkler( on == false ) f : Fire( room == s.room ) then modify( s ) { setOn( true ) } System.out.println( "Turn on the sprinkler for room " + f.getRoom().getName() ); end rule TurnSprinklerOff when s : Sprinkler( on == true ) not Fire( room == s.room ) then modify( s ) { setOn( false ) } System.out.println( "Turn off the sprinkler for room " + s.getRoom().getName() ); end rule OK when not Alarm() not Sprinkler( on == true ) then System.out.println( "Everything is ok" ); end Pattern-matching against objects in the Working Memory Code executed when a match is found
What is used by Quarkus ➱ A polyglot VM with cross-language JIT supporting ● Java Bytecode and JVM languages ● Interop with different languages ● Dynamic languages through Truffle API ➱ Cross-language interop out of the box ● Simple AST-based interpreter ● JIT across language boundaries ➱ Support for native binary compilation (SubstrateVM) ● faster boot-up ● lower memory footprint
AoT compilation with GraalVM ➱ Static analysis ➱ Closed world assumption ➱ Dead code elimination:      classes, fields, methods, branches
AoT compilation with GraalVM ➱ Static analysis ➱ Closed world assumption ➱ Dead code elimination:      classes, fields, methods, branches 🚀 Fast process start 🔬 Less memory đŸ’Ÿ Small size on disk
GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } }
GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } }
GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle
GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle
GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle Reflection Requires registration (closed world assumption)
GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle [ { "name" : "org.domain.model.Person", "allPublicConstructors" : true, "allPublicMethods" : true } ] Reflection Requires registration (closed world assumption) -H:ReflectionConfigurationFiles=src/main/resources/reflection.json
Drools on GraalVM - Executable Model rule "Older than Mark" when $p1: Person( name == "Mark" ) $p2: Person( name != "Mark", age > $p1.age ) then System.out.println( $p1.getName() + " is older than " + $p2.getName() ); end Variable<Person> markV = declarationOf( Person.class ); Variable<Person> olderV = declarationOf( Person.class ); Rule rule = rule( "Older than Mark" ) .build( pattern(markV) .expr("exprA", p -> p.getName().equals( "Mark" ), alphaIndexedBy( String.class, ConstraintType.EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name", "age" )), pattern(olderV) .expr("exprB", p -> !p.getName().equals("Mark"), alphaIndexedBy( String.class, ConstraintType.NOT_EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name" )) .expr("exprC", markV, (p1, p2) -> p1.getAge() > p2.getAge(), betaIndexedBy( int.class, ConstraintType.GREATER_THAN, 0, p -> p.getAge(), p -> p.getAge() ), reactOn( "age" )), on(olderV, markV).execute((p1, p2) -> System.out.println( p1.getName() + " is older than " + p2.getName() )) )
Drools on GraalVM - Executable Model rule "Older than Mark" when $p1: Person( name == "Mark" ) $p2: Person( name != "Mark", age > $p1.age ) then System.out.println( $p1.getName() + " is older than " + $p2.getName() ); end Variable<Person> markV = declarationOf( Person.class ); Variable<Person> olderV = declarationOf( Person.class ); Rule rule = rule( "Older than Mark" ) .build( pattern(markV) .expr("exprA", p -> p.getName().equals( "Mark" ), alphaIndexedBy( String.class, ConstraintType.EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name", "age" )), pattern(olderV) .expr("exprB", p -> !p.getName().equals("Mark"), alphaIndexedBy( String.class, ConstraintType.NOT_EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name" )) .expr("exprC", markV, (p1, p2) -> p1.getAge() > p2.getAge(), betaIndexedBy( int.class, ConstraintType.GREATER_THAN, 0, p -> p.getAge(), p -> p.getAge() ), reactOn( "age" )), on(olderV, markV).execute((p1, p2) -> System.out.println( p1.getName() + " is older than " + p2.getName() )) )
Drools on GraalVM - Executable Model rule "Older than Mark" when $p1: Person( name == "Mark" ) $p2: Person( name != "Mark", age > $p1.age ) then System.out.println( $p1.getName() + " is older than " + $p2.getName() ); end Variable<Person> markV = declarationOf( Person.class ); Variable<Person> olderV = declarationOf( Person.class ); Rule rule = rule( "Older than Mark" ) .build( pattern(markV) .expr("exprA", p -> p.getName().equals( "Mark" ), alphaIndexedBy( String.class, ConstraintType.EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name", "age" )), pattern(olderV) .expr("exprB", p -> !p.getName().equals("Mark"), alphaIndexedBy( String.class, ConstraintType.NOT_EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name" )) .expr("exprC", markV, (p1, p2) -> p1.getAge() > p2.getAge(), betaIndexedBy( int.class, ConstraintType.GREATER_THAN, 0, p -> p.getAge(), p -> p.getAge() ), reactOn( "age" )), on(olderV, markV).execute((p1, p2) -> System.out.println( p1.getName() + " is older than " + p2.getName() )) ) Executable model Indexes and reactivity explicitly defined
Executable Model at a glance ➱ A pure Java DSL for Drools rules authoring ➱ A pure Java canonical representation of a rule base ➱ Automatically generated by Maven plugin or Quarkus extension ● Can be embedded in jar ● Faster boot ➱ Improve Backward/Forward compatibility ➱ Allow for faster prototyping and experimentation of new features ➱ Prerequisite to make Drools natively compilable on GraalVM
public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { throw new UnsupportedOperationException(); } } Drools on GraalVM – other refactors Dynamic class definition is no longer necessary
public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { throw new UnsupportedOperationException(); } } Drools on GraalVM – other refactors Dynamic class definition is no longer necessary <?xml version="1.0" encoding="UTF-8"?> <kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule"> <kbase name="simpleKB" packages="org.drools.simple.project"> <ksession name="simpleKS" default="true"/> </kbase> </kmodule> var m = KieServices.get().newKieModuleModel(); var kb = m.newKieBaseModel("simpleKB"); kb.setEventProcessingMode(CLOUD); kb.addPackage("org.drools.simple.project"); var ks = kb.newKieSessionModel("simpleKS"); ks.setDefault(true); ks.setType(STATEFUL); ks.setClockType(ClockTypeOption.get("realtime"));
public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { throw new UnsupportedOperationException(); } } Drools on GraalVM – other refactors Dynamic class definition is no longer necessary <?xml version="1.0" encoding="UTF-8"?> <kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule"> <kbase name="simpleKB" packages="org.drools.simple.project"> <ksession name="simpleKS" default="true"/> </kbase> </kmodule> var m = KieServices.get().newKieModuleModel(); var kb = m.newKieBaseModel("simpleKB"); kb.setEventProcessingMode(CLOUD); kb.addPackage("org.drools.simple.project"); var ks = kb.newKieSessionModel("simpleKS"); ks.setDefault(true); ks.setType(STATEFUL); ks.setClockType(ClockTypeOption.get("realtime")); org.kie.api.io.KieResources = org.drools.core.io.impl.ResourceFactoryServiceImpl org.kie.api.marshalling.KieMarshallers = org.drools.core.marshalling.MarshallerProviderImpl org.kie.api.concurrent.KieExecutors = org.drools.core.concurrent.ExecutorProviderImpl Map<Class<?>, Object> serviceMap = new HashMap<>(); void wireServices() { serviceMap.put( ServiceInterface.class, Class.forName("org.drools.ServiceImpl") .newInstance()); // 
 more services here }
Demo 1 Drools on GraalVM
Introducing ➱ A Framework for writing (fast and lightweight) Java applications
Introducing ➱ A Framework for writing (fast and lightweight) Java applications ➱ (Optionally) allowing generation of native executable via GraalVM *.class QUARKUS optimized jar native executable JVM Maven/Gradle plugin
Introducing ➱ A Framework for writing (fast and lightweight) Java applications ➱ (Optionally) allowing generation of native executable via GraalVM ➱ Based on existing standard ● Servlet ● JAX-RS ● JPA, JDBC ● CDI ● Bean Validation ● Transactions ● Logging ● Microprofile *.class QUARKUS optimized jar native executable JVM Maven/Gradle plugin
Introducing ➱ A Framework for writing (fast and lightweight) Java applications ➱ (Optionally) allowing generation of native executable via GraalVM ➱ Based on existing standard ● Servlet ● JAX-RS ● JPA, JDBC ● CDI ● Bean Validation ● Transactions ● Logging ● Microprofile ➱ Out-of-the-box integration with libraries that you already know *.class QUARKUS optimized jar native executable JVM Maven/Gradle plugin
Why Quarkus Lower memory usage Faster startup Optimized for short-lived processes Kubernetes Native Live reload Microservices
Why Quarkus Lower memory usage Faster startup Optimized for short-lived processes Kubernetes Native Live reload Microservices
Fast, lightweight Drools = Submarine The question of whether a computer can think is no more interesting than the question of whether a submarine can swim - Edsger W. Dijkstra
Integrating Quarkus and Drools Writing a Quarkus extension public class ExecutableModelGenerator { private static final String PRODUCER_SOURCE = "package io.quarkus.drools.runtime;n" + "import org.drools.modelcompiler.KieRuntimeBuilder;n" + "n" + "@javax.inject.Singletonn" + "public class RuntimeProducer {n" + " public static final KieRuntimeBuilder INSTANCE = new org.drools.project.model.ProjectRuntime();n" + "n" + " @javax.enterprise.inject.Producesn" + " public KieRuntimeBuilder produce() { return INSTANCE; }n" + "}"; @BuildStep(providesCapabilities = "io.quarkus.drools") @Record(STATIC_INIT) public void generateModel( ArchiveRootBuildItem root, BuildProducer<GeneratedBeanBuildItem> generatedBeans, BuildProducer<GeneratedClassBuildItem> generatedClasses) { MemoryFileSystem srcMfs = new MemoryFileSystem(); String[] sources = generateSources(root, srcMfs); srcMfs.write(toRuntimeSource(PRODUCER_CLASSNAME), PRODUCER_SOURCE.getBytes()); sources[sources.length - 1] = toRuntimeSource(PRODUCER_CLASSNAME); registerGeneratedClasses(generatedBeans, generatedClasses, compileSources(srcMfs, sources)); } private void registerGeneratedClasses( BuildProducer<GeneratedBeanBuildItem> generatedBeans, BuildProducer<GeneratedClassBuildItem> generatedClasses, MemoryFileSystem trgMfs) { for (String fileName : trgMfs.getFileNames()) { String className = toClassName(fileName); if (className.equals(PRODUCER_CLASSNAME)) { generatedBeans.produce(new GeneratedBeanBuildItem(className, trgMfs.getBytes(fileName))); } else { generatedClasses.produce(new GeneratedClassBuildItem(true, className, trgMfs.getBytes(fileName))); } } } }
A simple Quarkus-based REST endopint using Drools @Path("/candrink/{name}/{age}") public class CanDrinkResource { @Inject KieRuntimeBuilder runtimeBuilder; @GET @Produces(MediaType.TEXT_PLAIN) public String canDrink( @PathParam("name") String name, @PathParam("age") int age ) { KieSession ksession = runtimeBuilder.newKieSession("canDrinkKS"); Result result = new Result(); ksession.insert(result); ksession.insert(new Person( name, age )); ksession.fireAllRules(); return result.toString(); } }
Demo 2 Drools on Quarkus
Mario Fusco Red Hat – Principal Software Engineer mario.fusco@gmail.com twitter: @mariofusco Q A Thanks ... Questions?

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How and why I turned my old Java projects into a first-class serverless component

  • 1. How and why I turned my old Java projects into a first-class serverless component by Mario Fusco Red Hat – Principal Software Engineer @mariofusco c
  • 2. Agenda ➱ Declarative vs. Imperative programming ➱ What is a rule engine and how it works ➱ A simple example ➱ From drl to Java: the executable model
  • 3. Agenda ➱ Declarative vs. Imperative programming ➱ What is a rule engine and how it works ➱ A simple example ➱ From drl to Java: the executable model ➱ What is GraalVM ➱ AoT compilation ➱ Limitations ➱ Refactoring Drools to (natively) compile on GraalVM
  • 4. Agenda c ➱ Declarative vs. Imperative programming ➱ What is a rule engine and how it works ➱ A simple example ➱ From drl to Java: the executable model ➱ What is GraalVM ➱ AoT compilation ➱ Limitations ➱ Refactoring Drools to (natively) compile on GraalVM ➱ What is Quarkus ➱ Quarkus features ➱ Integrating Drools with Quarkus ➱ Writing a Quarkus extension for Drools
  • 5. What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions
  • 6. What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions Declarative (What to do) Imperative (How to do it) Vs. public void helloMark(Person person) { if ( person.getName().equals( “Mark” ) { System.out.println( “Hello Mark” ); } } rule “Hello Mark” when Person( name == “Mark” ) then System.out.println( “Hello Mark” ); end
  • 7. What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions Declarative (What to do) Imperative (How to do it) Vs. public void helloMark(Person person) { if ( person.getName().equals( “Mark” ) { System.out.println( “Hello Mark” ); } } rule “Hello Mark” when Person( name == “Mark” ) then System.out.println( “Hello Mark” ); end A method must be called directly Rules can never be called directly
  • 8. What a rule-based program is ➱ A rule-based program is made up of discrete rules, each of which applies to a subset of the problem ➱ It is simpler, because you can concentrate on the rules for one situation at a time ➱ It can be more flexible in the face of fragmentary or poorly conditioned inputs ➱ Used for problems involving control, diagnosis, prediction, classification, pattern recognition 
 in short, all problems without clear algorithmic solutions Declarative (What to do) Imperative (How to do it) Vs. public void helloMark(Person person) { if ( person.getName().equals( “Mark” ) { System.out.println( “Hello Mark” ); } } rule “Hello Mark” when Person( name == “Mark” ) then System.out.println( “Hello Mark” ); end A method must be called directly Specific passing of arguments Rules can never be called directly Specific instances cannot be passed but are automatically selected with pattern-matching
  • 9. Introducing ➱ Easier to understand → Requirements can be more naturally translated into rules. It is more likely for a technically skilled business analyst to verify, validate or even change a rule than a piece of Java code ➱ Improved maintainability → We don't care about how to implement a solution only what needs to be done to solve a problem ➱ Deals with evolving complexity → It's easier to modify a rule than a Java program and to determine the impact of this change on the rest of the application ➱ Modularity → Each rule models an isolated and small portion of your business logic and is not part of a monolithic program ➱ Clear separation of business logic from the rest of the system → Business and infrastructural code have very different lifecycles ➱ Complex Event Processing → Facts can be handled like timestamped events allowing temporal reasoning on them RULES
  • 10. How a rule-based system works ➱ The Rule Base contains a computation efficient representation of the set of the defined rules ➱ The Working Memory contains the set of facts inserted into sessions ➱ The engine matches the fact in the working memory against the rules set ➱ When a match is found it creates an activation and put it into the agenda ➱ An activation is the tuple of facts matching the conditions of a rule plus the rule itself ➱ When all activations have been created the agenda elects through a conflict resolution strategy the one to be executed ➱ The elected activation is passed to the execution engine and the fired
  • 11. A simple rule set rule RaiseAlarm when exists Fire() then insert( new Alarm( "house1" ) ); System.out.println( "Raise the Alarm"); end rule CancelAlarm when not Fire() a : Alarm() then delete( a ); System.out.println( "Cancel the Alarm"); end rule TurnSprinklerOn when s : Sprinkler( on == false ) f : Fire( room == s.room ) then modify( s ) { setOn( true ) } System.out.println( "Turn on the sprinkler for room " + f.getRoom().getName() ); end rule TurnSprinklerOff when s : Sprinkler( on == true ) not Fire( room == s.room ) then modify( s ) { setOn( false ) } System.out.println( "Turn off the sprinkler for room " + s.getRoom().getName() ); end rule OK when not Alarm() not Sprinkler( on == true ) then System.out.println( "Everything is ok" ); end Pattern-matching against objects in the Working Memory Code executed when a match is found
  • 12. What is used by Quarkus ➱ A polyglot VM with cross-language JIT supporting ● Java Bytecode and JVM languages ● Interop with different languages ● Dynamic languages through Truffle API ➱ Cross-language interop out of the box ● Simple AST-based interpreter ● JIT across language boundaries ➱ Support for native binary compilation (SubstrateVM) ● faster boot-up ● lower memory footprint
  • 13. AoT compilation with GraalVM ➱ Static analysis ➱ Closed world assumption ➱ Dead code elimination:      classes, fields, methods, branches
  • 14. AoT compilation with GraalVM ➱ Static analysis ➱ Closed world assumption ➱ Dead code elimination:      classes, fields, methods, branches 🚀 Fast process start 🔬 Less memory đŸ’Ÿ Small size on disk
  • 15. GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } }
  • 16. GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } }
  • 17. GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle
  • 18. GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle
  • 19. GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle Reflection Requires registration (closed world assumption)
  • 20. GraalVM Limitations Dynaminc Classloading Deloying jars, wars, etc. at runtime impossible public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { return defineClass( name, bytecode, 0, bytecode.length ); } } JVMTI, JMX + other native VM interfaces No agents → No JRebel, Byteman, profilers, tracers Miscellaneous ➱ Security Manager ➱ finalize() (depreceated anyway) ➱ InvokeDynamic and MethodHandle [ { "name" : "org.domain.model.Person", "allPublicConstructors" : true, "allPublicMethods" : true } ] Reflection Requires registration (closed world assumption) -H:ReflectionConfigurationFiles=src/main/resources/reflection.json
  • 21. Drools on GraalVM - Executable Model rule "Older than Mark" when $p1: Person( name == "Mark" ) $p2: Person( name != "Mark", age > $p1.age ) then System.out.println( $p1.getName() + " is older than " + $p2.getName() ); end Variable<Person> markV = declarationOf( Person.class ); Variable<Person> olderV = declarationOf( Person.class ); Rule rule = rule( "Older than Mark" ) .build( pattern(markV) .expr("exprA", p -> p.getName().equals( "Mark" ), alphaIndexedBy( String.class, ConstraintType.EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name", "age" )), pattern(olderV) .expr("exprB", p -> !p.getName().equals("Mark"), alphaIndexedBy( String.class, ConstraintType.NOT_EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name" )) .expr("exprC", markV, (p1, p2) -> p1.getAge() > p2.getAge(), betaIndexedBy( int.class, ConstraintType.GREATER_THAN, 0, p -> p.getAge(), p -> p.getAge() ), reactOn( "age" )), on(olderV, markV).execute((p1, p2) -> System.out.println( p1.getName() + " is older than " + p2.getName() )) )
  • 22. Drools on GraalVM - Executable Model rule "Older than Mark" when $p1: Person( name == "Mark" ) $p2: Person( name != "Mark", age > $p1.age ) then System.out.println( $p1.getName() + " is older than " + $p2.getName() ); end Variable<Person> markV = declarationOf( Person.class ); Variable<Person> olderV = declarationOf( Person.class ); Rule rule = rule( "Older than Mark" ) .build( pattern(markV) .expr("exprA", p -> p.getName().equals( "Mark" ), alphaIndexedBy( String.class, ConstraintType.EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name", "age" )), pattern(olderV) .expr("exprB", p -> !p.getName().equals("Mark"), alphaIndexedBy( String.class, ConstraintType.NOT_EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name" )) .expr("exprC", markV, (p1, p2) -> p1.getAge() > p2.getAge(), betaIndexedBy( int.class, ConstraintType.GREATER_THAN, 0, p -> p.getAge(), p -> p.getAge() ), reactOn( "age" )), on(olderV, markV).execute((p1, p2) -> System.out.println( p1.getName() + " is older than " + p2.getName() )) )
  • 23. Drools on GraalVM - Executable Model rule "Older than Mark" when $p1: Person( name == "Mark" ) $p2: Person( name != "Mark", age > $p1.age ) then System.out.println( $p1.getName() + " is older than " + $p2.getName() ); end Variable<Person> markV = declarationOf( Person.class ); Variable<Person> olderV = declarationOf( Person.class ); Rule rule = rule( "Older than Mark" ) .build( pattern(markV) .expr("exprA", p -> p.getName().equals( "Mark" ), alphaIndexedBy( String.class, ConstraintType.EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name", "age" )), pattern(olderV) .expr("exprB", p -> !p.getName().equals("Mark"), alphaIndexedBy( String.class, ConstraintType.NOT_EQUAL, 1, p -> p.getName(), "Mark" ), reactOn( "name" )) .expr("exprC", markV, (p1, p2) -> p1.getAge() > p2.getAge(), betaIndexedBy( int.class, ConstraintType.GREATER_THAN, 0, p -> p.getAge(), p -> p.getAge() ), reactOn( "age" )), on(olderV, markV).execute((p1, p2) -> System.out.println( p1.getName() + " is older than " + p2.getName() )) ) Executable model Indexes and reactivity explicitly defined
  • 24. Executable Model at a glance ➱ A pure Java DSL for Drools rules authoring ➱ A pure Java canonical representation of a rule base ➱ Automatically generated by Maven plugin or Quarkus extension ● Can be embedded in jar ● Faster boot ➱ Improve Backward/Forward compatibility ➱ Allow for faster prototyping and experimentation of new features ➱ Prerequisite to make Drools natively compilable on GraalVM
  • 25. public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { throw new UnsupportedOperationException(); } } Drools on GraalVM – other refactors Dynamic class definition is no longer necessary
  • 26. public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { throw new UnsupportedOperationException(); } } Drools on GraalVM – other refactors Dynamic class definition is no longer necessary <?xml version="1.0" encoding="UTF-8"?> <kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule"> <kbase name="simpleKB" packages="org.drools.simple.project"> <ksession name="simpleKS" default="true"/> </kbase> </kmodule> var m = KieServices.get().newKieModuleModel(); var kb = m.newKieBaseModel("simpleKB"); kb.setEventProcessingMode(CLOUD); kb.addPackage("org.drools.simple.project"); var ks = kb.newKieSessionModel("simpleKS"); ks.setDefault(true); ks.setType(STATEFUL); ks.setClockType(ClockTypeOption.get("realtime"));
  • 27. public class InternalClassLoader extends ClassLoader { public Class<?> defineClass( String name, byte[] bytecode ) { throw new UnsupportedOperationException(); } } Drools on GraalVM – other refactors Dynamic class definition is no longer necessary <?xml version="1.0" encoding="UTF-8"?> <kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule"> <kbase name="simpleKB" packages="org.drools.simple.project"> <ksession name="simpleKS" default="true"/> </kbase> </kmodule> var m = KieServices.get().newKieModuleModel(); var kb = m.newKieBaseModel("simpleKB"); kb.setEventProcessingMode(CLOUD); kb.addPackage("org.drools.simple.project"); var ks = kb.newKieSessionModel("simpleKS"); ks.setDefault(true); ks.setType(STATEFUL); ks.setClockType(ClockTypeOption.get("realtime")); org.kie.api.io.KieResources = org.drools.core.io.impl.ResourceFactoryServiceImpl org.kie.api.marshalling.KieMarshallers = org.drools.core.marshalling.MarshallerProviderImpl org.kie.api.concurrent.KieExecutors = org.drools.core.concurrent.ExecutorProviderImpl Map<Class<?>, Object> serviceMap = new HashMap<>(); void wireServices() { serviceMap.put( ServiceInterface.class, Class.forName("org.drools.ServiceImpl") .newInstance()); // 
 more services here }
  • 28. Demo 1 Drools on GraalVM
  • 29. Introducing ➱ A Framework for writing (fast and lightweight) Java applications
  • 30. Introducing ➱ A Framework for writing (fast and lightweight) Java applications ➱ (Optionally) allowing generation of native executable via GraalVM *.class QUARKUS optimized jar native executable JVM Maven/Gradle plugin
  • 31. Introducing ➱ A Framework for writing (fast and lightweight) Java applications ➱ (Optionally) allowing generation of native executable via GraalVM ➱ Based on existing standard ● Servlet ● JAX-RS ● JPA, JDBC ● CDI ● Bean Validation ● Transactions ● Logging ● Microprofile *.class QUARKUS optimized jar native executable JVM Maven/Gradle plugin
  • 32. Introducing ➱ A Framework for writing (fast and lightweight) Java applications ➱ (Optionally) allowing generation of native executable via GraalVM ➱ Based on existing standard ● Servlet ● JAX-RS ● JPA, JDBC ● CDI ● Bean Validation ● Transactions ● Logging ● Microprofile ➱ Out-of-the-box integration with libraries that you already know *.class QUARKUS optimized jar native executable JVM Maven/Gradle plugin
  • 35. Fast, lightweight Drools = Submarine The question of whether a computer can think is no more interesting than the question of whether a submarine can swim - Edsger W. Dijkstra
  • 36. Integrating Quarkus and Drools Writing a Quarkus extension public class ExecutableModelGenerator { private static final String PRODUCER_SOURCE = "package io.quarkus.drools.runtime;n" + "import org.drools.modelcompiler.KieRuntimeBuilder;n" + "n" + "@javax.inject.Singletonn" + "public class RuntimeProducer {n" + " public static final KieRuntimeBuilder INSTANCE = new org.drools.project.model.ProjectRuntime();n" + "n" + " @javax.enterprise.inject.Producesn" + " public KieRuntimeBuilder produce() { return INSTANCE; }n" + "}"; @BuildStep(providesCapabilities = "io.quarkus.drools") @Record(STATIC_INIT) public void generateModel( ArchiveRootBuildItem root, BuildProducer<GeneratedBeanBuildItem> generatedBeans, BuildProducer<GeneratedClassBuildItem> generatedClasses) { MemoryFileSystem srcMfs = new MemoryFileSystem(); String[] sources = generateSources(root, srcMfs); srcMfs.write(toRuntimeSource(PRODUCER_CLASSNAME), PRODUCER_SOURCE.getBytes()); sources[sources.length - 1] = toRuntimeSource(PRODUCER_CLASSNAME); registerGeneratedClasses(generatedBeans, generatedClasses, compileSources(srcMfs, sources)); } private void registerGeneratedClasses( BuildProducer<GeneratedBeanBuildItem> generatedBeans, BuildProducer<GeneratedClassBuildItem> generatedClasses, MemoryFileSystem trgMfs) { for (String fileName : trgMfs.getFileNames()) { String className = toClassName(fileName); if (className.equals(PRODUCER_CLASSNAME)) { generatedBeans.produce(new GeneratedBeanBuildItem(className, trgMfs.getBytes(fileName))); } else { generatedClasses.produce(new GeneratedClassBuildItem(true, className, trgMfs.getBytes(fileName))); } } } }
  • 37. A simple Quarkus-based REST endopint using Drools @Path("/candrink/{name}/{age}") public class CanDrinkResource { @Inject KieRuntimeBuilder runtimeBuilder; @GET @Produces(MediaType.TEXT_PLAIN) public String canDrink( @PathParam("name") String name, @PathParam("age") int age ) { KieSession ksession = runtimeBuilder.newKieSession("canDrinkKS"); Result result = new Result(); ksession.insert(result); ksession.insert(new Person( name, age )); ksession.fireAllRules(); return result.toString(); } }
  • 38. Demo 2 Drools on Quarkus
  • 39. Mario Fusco Red Hat – Principal Software Engineer [email protected] twitter: @mariofusco Q A Thanks ... Questions?