CDI 2.0 is upon us Devoxx

@antoine_sd @cdispec#Devoxx #CDI2
CDI 2.0 is upon us
Antoine Sabot-Durand
Red Hat
CDI spec lead

Me, Myself and I
Antoine Sabot-Durand
Software Engineer at Red Hat
CDI spec lead
CDI evangelist
Follow me: @antoine_sd
Follow CDI: @cdispec

Agenda
Flashback on CDI & CDI 2.0 status
CDI 2.0 new features
Java SE support
Enhancing events
Metadata conﬁgurators
Interceptor and Decorators on Produced / custom beans (coming)
Questions and Feedback

CDI Timeline
Dec 2009 June 2013 Apr 2014 Sep 2014
CDI1.0
(Java
EE
6)
CDI1.1
(Java
EE
7)
CDI1.2
(1.1
MR)
CDI2.0
Starts
jan 2017
CDI2.0
released

CDI 1.0 - December 2009
A well-defined lifecycle for stateful objects bound to lifecycle contexts
Where the set of contexts is extensible
A type-safe dependency injection mechanism without verbose configuration
Dependencies can be selected at development or deployment time
Type-safe decorators and interceptors
An event notification model
An SPI allowing portable extensions to integrate cleanly with the container

CDI 1.1 / 1.2 – June 2013 / April 2014
Add automatic enablement of CDI in Java EE
Add introspection with event, bean, decorator and interceptor meta data
Ease access to bean manager from outside CDI with CDI class
Add global enablement of interceptors using the @Priority annotation
Add Unmanaged allowing easy access to non-contexutal instances
Spec clariﬁcation

CDI 1.2 - April 2014
Clarification in the spec regarding:
CDI Lifecycle
Events
Reworking Bean defining annotation to avoid conflict with other JSR 330
frameworks
Clarification on conversation resolution
OSGi official support in the API

CDI 2.0 status
JSR 365 started in September 2014
EDR1 released in 2015
EDR2 released in august.
Weld 3 Alpha 17 is the RI for EDR2
Release expected in January 2017

cdi-spec.org

CDI 2.0 new features

Java SE support
using CDI outside Java EE

Java SE support - Why?
To align on many other Java EE spec which support Java SE bootstrapping
To boost CDI adoption for Spec and Frameworks
To provide a mean of building new stacks out of Java EE

What did we do?
CDI Specification
CDI Core CDI for Java EECDI for Java SE

Java SE bootstrap API
public static void main(String[] args) { 
 
SeContainer container = SeContainerInitializer.newInstance() 
.disableDiscovery() 
.addBeanClasses(MyService.class) 
.initialize(); 
 
MyService service = container.select(MyService.class).get(); 
 
service.sayHello(); 
 
container.close(); 
}

Controlling the Request Context
In Java SE, most of our built-in contexts are unavailable:
Request context
Session context
Conversation context
That’s why we added tools to activate Request context programmatically
This feature is also available for Java EE

Controlling the Request Context
@ApplicationScoped 
public class MyBean { 
 
@Inject 
private RequestContextController requestContextController; 
 
public void doRequest(String body) { 
// activate request context 
requestContextController.activate(); 
 
// do work in a request context. 
 
// deactivate the request context 
requestContextController.deactivate(); 
} 
 
}

In interceptor mode
@ApplicationScoped 
public class MyBean { 
 
@ActivateRequestContext 
public void doRequest(String body) { 
// Request Context will be activated during this invocation 
} 
}

Enhancing events
Making popular feature even more popular

Enhancing events
CDI events are a very loved feature
We took a very long time to see how to enhance them
In CDI 2.0 we are introducing
Event ordering
Asynchronous events

Events ordering
By adding a @Priority (from commons annotations) on an observer.
The lowest value is ﬁrst
Observers with no explicit priority have a middle range priority
Allowing observer to be called last
Observer with the same priority are called in an undeﬁned order
No priority on async events

Events ordering
public void observer1(@Observes @Priority(1) Payload p) {
}
public void observer2(@Observes @Priority(2) Payload p) {
}

Events ordering in extensions
public class MyExtension implements Extension { 
 
public void firstPat(@Observes @Priority(1) ProcessAnnotatedType<?> pat) {
… 
} 
public void secondPat(@Observes @Priority(2) ProcessAnnotatedType<?> pat) {
… 
} 
 
}

CDI 1.x: Sync / Async
Sync / Async is not speciﬁed
The immutable status of the payload is not speciﬁed
Implementations use a Sync model
The payload is mutated in some implementations / framework
Going async “blindly” might raise problems…

Synchronous events - ﬁring pattern
@Inject 
Event<Payload> event; 
public void someBSCriticalBusinessMethod() { 
event.fire(new Payload()); 
}

Synchronous events - observing pattern
public void callMe(@Observes Payload payload) { 
// Do something with the event
}

Events are sync in CDI 1
All the observers are called in the ﬁring thread
In no particular order (at least not speciﬁed)
The payload may be mutated
Observers may inject beans
Observers are aware of Transactional and security contexts

Asynchronous Events
Async events can’t:
Mute Payload
Access CDI contexts states at the ﬁring point
Be transactional
So designing backward compatible async events is more tricky than it looks:
A currently sync event should remain sync
Going sync / async should be a decision taken from the ﬁring side
Being sync should be possible from the observing side

Async events - ﬁring pattern
@Inject 
Event<Payload> event; 
public void someEvenMoreCriticalBusinessMethod() {
 
event.fireAsync(new Payload()); 
}

Async events - observing pattern
public void callMe(@ObservesAsync Payload payload) { 
// I am called in another thread
}

Sync vs Async Events in a nutshell
callMe(@Observes payload) callMe(@ObservesAsync payload)
event.fire(payload) Sync call Not notiﬁed
event.fireAsync(payload) Not notiﬁed Async call

Adding an Executor to ﬁreAsync
@Inject 
Event<PanelUpdater> event; 
public void someOtherCriticalBusinessMethod() {
 
event.fireAsync(new PanelUpdater(green),  
executor);
}

Async event in the GUI thread
@Inject 
 
event.fireAsync(new PanelUpdater(green),
SwingUtilities::invokeLater); 
}

Handling exceptions
@Inject 
 
CompletionStage<PanelUpdater> stage =  
event.fireAsync(new PanelUpdater(green),
SwingUtilities::invokeLater); 
}

Handling exceptions
Exception in one async observer doesn’t stop execution as in sync observer
One of the reasons why ﬁring async event doesn’t trigger sync observers
Event.fireAsync returns a CompletionStage
Allowing integration of async events in standard Java 8 async pipeline

Handling exceptions
The Exception in fireAsync returned CompletionStage is
CompletionException
It holds all the exceptions in the suppressed exception set

Handling exceptions
Exception handling is done with the Standard Java 8 async api, with:
stage.whenComplete() to deal with result or exception
stage.handle() same as above but allows transformation of stage
stage.exceptionally() to only treat exception case

SPI enhancement
New conﬁgurators for meta data

Standard annotations instances
CDI makes an heavy use of Annotations
Java doesn’t provide easy way to create an annotation instance
We provided AnnotationLiteral, to help users create their instances
Annotation instance = new AnnotationLiteral<ApplicationScoped>(){};

When members are here a class has to be created
public class NamedLiteral extends AnnotationLiteral<Named> implements Named{ 
 
private String value; 
 
public NamedLiteral(String value) { 
this.value = value; 
} 
 
@Override 
public String value() { 
return null; 
} 
}

CDI 2.0 provides helpers out of the box
ApplicationScoped literal = ApplicationScoped.Literal.INSTANCE;
 
Named literal2 = NamedLiteral.of("myName");

Conﬁgurators for meta-data
Some meta-data are very verbose to create
AnnotatedType
Bean
InjectionPoint
ObserverMethod
If you only need to add info to an existing meta-data, it’s very boring

Example with CDI 1.2
I have a legacy framework
I want to adapt it for CDI
I need to detect all @CacheContext annotations on ﬁelds…
...And transform them in injection point
I’ll use an extension to replace @CacheContext annotation by @Inject in
AnnotatedTypes

Example 1/7
First we need to implement an AnnotatedType to decorate the original one
and modify AnnotatedField set

Example 2/7
public class AutoInjectingAnnotatedType<X> implements AnnotatedType<X> { 
 
private final AnnotatedType<X> delegate; 
private final Set<AnnotatedField<? super X>> fields; 
 
public AutoInjectingAnnotatedType(AnnotatedType<X> delegate) { 
this.delegate = delegate; 
fields = new HashSet<>(); 
for (AnnotatedField<? super X> field : delegate.getFields()) { 
if (field.isAnnotationPresent(CacheContext.class)) 
fields.add(new AutoInjectingAnnotatedField(field)); 
else 
fields.add(field); 
} 
} 
…

Example 3/7
… 
public Set<AnnotatedField<? super X>> getFields() { 
return fields; 
} 
public Class<X> getJavaClass() { 
return delegate.getJavaClass(); 
} 
// 7 more similar methods
 
}

Example 4/7
Then we need to do the same for AnnotatedField to add @Inject to the
ﬁeld annotations set
public class AutoInjectingAnnotatedField<X> implements AnnotatedField<X> { 
 
private final Set<Annotation> annotations; 
private final AnnotatedField<X> delegate; 
 
public AutoInjectingAnnotatedField(AnnotatedField<X> delegate) { 
this.delegate = delegate; 
annotations = new HashSet<>(delegate.getAnnotations()); 
annotations.add(new InjectLiteral()); 
} 
…

Example 5/7
public <T extends Annotation> T getAnnotation(Class<T> annotationType) { 
if (annotationType.equals(Inject.class)) 
return (T) new InjectLiteral(); 
return delegate.getAnnotation(annotationType); 
} 
 
public Set<Annotation> getAnnotations() { 
return annotations; 
} 
...

Example 6/7
public boolean isAnnotationPresent(Class<? extends Annotation> annotationType) { 
if (annotationType.equals(Inject.class)) 
return true; 
return delegate.isAnnotationPresent(annotationType); 
}
public Set<Type> getTypeClosure() { 
return delegate.getTypeClosure(); 
} 
// 4 similar methods
 
}

Example 7/7
Finaly we need to write the extension to use our custom AnnotatedType
and AnnotatedField
public class AutoInjectExtension implements Extension { 
 
public <T> void CreateIP(
@Observes @WithAnnotations(CacheContext.class)
ProcessAnnotatedType<T> pat) { 
pat.setAnnotatedType(
new AutoInjectingAnnotatedType<T>(pat.getAnnotatedType())); 
} 
}

In CDI 2.0
We introduced conﬁgurators, helping creation of these metadata
This conﬁgurators are accessible thru container lifecycle events
They are automatically built by the container at the end of
observer invocation

In CDI 2.0
All the previous code ﬁts in this extension
public class AutoInjectExtension implements Extension { 
 
public <T> void CreateIP(
@Observes @WithAnnotations(CacheContext.class) ProcessAnnotatedType<T> pat)
{ 
pat.configureAnnotatedType().filterFields(
f -> f.isAnnotationPresent(CacheContext.class)
) 
.forEach(f -> f.add(InjectLiteral.INSTANCE));
} 
}

AOP enhancement
Support AOP on custom or produced bean

Support AOP on producer
In CDI 1.x you cannot bind an interceptor to a produced bean
When you write:
@Transactional is applied to producer method
@Produces 
@Transactional
public MyService produceService() {
...
}

Support Interceptor on producer
Answer is probably the new InterceptionFactory
This factory uses an AnnotatedType to know where adding interceptor bindings in
the class
Could also be used in Custom Bean create method
public interface InterceptionFactory<T> { 
 
InterceptionProxyFactory<T> ignoreFinalMethods(); 
 
AnnotatedTypeConfigurator<T> configure(); 
 
<T> T createInterceptedInstance(T InstanceToWrap); 
 
}

Add @transaction on one produced bean method
@Produces 
@RequestScoped 
public MyClass createJpaEmAssumed(InterceptionFactory<MyClass> ify) { 
AnnotatedTypeConfigurator<MyClass> atc = ify.configure(); 
 
atc.filterMethods(m -> m.getJavaMember().getName().equals("doSomething")) 
.findFirst()
.ifPresent(m -> m.add(new AnnotationLiteral<Transactional>() { })); 
 
return ify.createInterceptedInstance(new MyClass()); 
 
}

CDI 2.0 needs you
CDI 2.0 speciﬁcation is open to everyone
Come on join us on the mailing list and IRC channel
All infos on http://cdi-spec.org or by following to @cdispec on
twitter
The more we are the more we’ll deliver

Which JSR you’ll use 365 days a year?
…
JSR 365

CDI 2.0 is upon us Devoxx

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