CDI 2.0

Contexts and Dependency Injection has become an integral part of Java to leverage dependency injection and bean management aside of EJB. The current CDI 1.2 is widely used amongst Java Enterprise 7 applications. The Expert Group formed in Fall 2014 to work on the next version of the specification and released the CDI 2.0 spec in early 2017, which will be part of Java Enterprise 8.

Links:
* Code: https://github.com/mp911de/cdi-2.0

Transcript

1. What's New in CDI 2.0
   JSR 365 Mark Paluch • @mp911de
   

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2. CDI Timeline
   Dec 2009
   CDI 1.0
   (Java
   EE
   6)
   Jun 2013
   CDI 1.1 (Java
   EE
   7)
   Apr 2014
   CDI 1.2
   (M
   R)
   Sep 2014
   CDI 2.0
   (Kickoff)
   May 2017
   CDI 2.0
   (Release)
   Sept 2017?
   Java
   EE
   8
   

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3. CanDI
   

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4. Community Survey
   1. Asynchronous method invocation
   2. Add asynchronous event support
   3. @Startup for CDI
   4. Bootstrapping the container
   outside Java EE
   5. AOP for produced or custom
   beans

   6. Mutable container at runtime
   7. Security support
   8. Observers ordering
   9. Enhance SPI to give better access
   to all metadata
   10. Better EAR support
   Source: https://jcp.org/aboutJava/communityprocess/ec-public/materials/2015-06-1516/JSR-365-Review.pdf
   

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5. @ApplicationScoped
   class UserService {
   User createUser() {
   return …;
   }
   }
   class UserServlet extends HttpServlet {
   @Inject
   UserService service;
   }
   

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6. @ApplicationScoped
   class UserService {
   void onUserCreated(@Observes UserEvent event) {
   }
   }
   class UserServlet extends HttpServlet {
   @Inject
   UserService service;
   }
   class UserServiceFactory {
   @Produces
   @ApplicationScoped
   UserService createService() {
   return new UserService();
   }
   }
   

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7. Road towards JavaEE 8
   • Java 8 baseline
   • Spec split: Core/SE/EE
   CDI Specification
   CDI Core
   CDI for
   Java SE
   CDI for
   Java EE
   

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8. Java SE
   

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9. Java SE
   • Currently: Implementation-specific in Weld/
   OpenWebBean
   • Spec Goal: Bootstrap API
   

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10. SeContainerInitializer initializer = SeContainerInitializer
    .newInstance()

    .disableDiscovery()

    .addBeanClasses(MyApp.class)

    .addPackages(MyOtherServices.class)

    .addExtensions(MyExtension.class);

    

    try (SeContainer container = initializer.initialize()) {

    

    MyApp service = container.select(MyService.class).get();

    service.runMyApplication();

    }
    

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11. SeContainerInitializer initializer = SeContainerInitializer
    .newInstance()

    .disableDiscovery()

    .addBeanClasses(MyApp.class)

    .addPackages(MyOtherServices.class)

    .addExtensions(MyExtension.class);

    

    try (SeContainer container = initializer.initialize()) {

    

    MyApp service = container.select(MyService.class).get();

    service.runMyApplication();

    }
    

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12. SeContainerInitializer initializer = SeContainerInitializer
    .newInstance()

    .disableDiscovery()

    .addBeanClasses(MyApp.class)

    .addPackages(MyOtherServices.class)

    .addExtensions(MyExtension.class);

    

    try (SeContainer container = initializer.initialize()) {

    

    MyApp service = container.select(MyService.class).get();

    service.runMyApplication();

    }
    

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13. Events
    

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14. @Observes
    

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15. @Priority
    

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16. Ordered Events
    • Add @Priority to event observers
    • Aids observer ordering
    • Total global order determined when the event is fired
    

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17. Observer Ordering
    public void observer(@Observes @Priority(2500) MyEvent event) {

    System.out.println("Default priority");

    }
    

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18. public void earlier(@Observes @Priority(2499) MyEvent event) {

    // yay! I'm first

    System.out.println("Notified before all other observers");

    }

    public void observer(@Observes MyEvent event) {

    System.out.println("Default priority");

    }
    public void later(@Observes @Priority(2501) MyEvent event) {

    System.out.println("Notified after all other observers");

    }
    

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19. public void earlier(@Observes @Priority(2499) MyEvent event) {

    // yay! I'm first

    System.out.println("Notified before all other observers");

    }

    public void observer(@Observes MyEvent event) {

    System.out.println("Default priority");

    }
    public void later(@Observes @Priority(2501) MyEvent event) {

    System.out.println("Notified after all other observers");

    }
    

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20. public void earlier(@Observes @Priority(2499) MyEvent event) {

    // yay! I'm first

    System.out.println("Notified before all other observers");

    }

    public void observer(@Observes MyEvent event) {

    System.out.println("Default priority");

    }
    public void later(@Observes @Priority(2501) MyEvent event) {

    System.out.println("Notified after all other observers");

    }
    

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21. public void earlier(@Observes @Priority(2499) MyEvent event) {

    // yay! I'm first

    System.out.println("Notified before all other observers");

    }

    public void observer(@Observes MyEvent event) {

    System.out.println("Default priority");

    }
    public void later(@Observes @Priority(2501) MyEvent event) {

    System.out.println("Notified after all other observers");

    }
    

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22. @ObservesAsync
    

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23. Asynchronous Events
    • Notify event observers asynchronously
    • One or more different threads
    • Decoupled from synchronous events
    

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24. Firing Async Events
    @Inject

    private Event event;

    public void triggerEvent() {

    event.fireAsync(new MyEventPayload());

    }
    

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25. Firing Async Events
    @Inject

    private Event event;

    public void triggerEvent() {

    event.fireAsync(new MyEventPayload());

    }
    

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26. Observing Async Events
    public void observer(@ObservesAsync MyEvent payload) {

    System.out.println("Yay, I'm called async!");

    }
    

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27. How it works
    @Observes @ObservesAsync
    event.fire(…)
    Sync call Not notified
    event.fireAsync(…)
    Not notified Async call
    

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28. Asynchronous Events
    • Exceptions and Synchronization with
    CompletionStage
    • Active scopes: Request, Application
    • Custom scopes depend on the implementation
    

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29. Portable Extensions
    

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30. Meta-Data Builder API
    • Standardized API
    • CDI 1.0+: Very verbose to create
    • AnnotatedTypes, Beans, BeanAttributes, InjectionPoints, and
    ObserverMethods
    • Builder and Configurator-style
    

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31. class AfterBeanDiscoveryExtension implements Extension {

    void afterBeanDiscovery(
    @Observes AfterBeanDiscovery event) {

    event.addBean()
    .types(MyService.class)
    .scope(RequestScoped.class)
    .createWith(ctx -> …)
    .name("myservice");
    }
    }
    Add a Bean
    

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32. class AfterBeanDiscoveryExtension implements Extension {

    void afterBeanDiscovery(
    @Observes AfterBeanDiscovery event) {

    event.addBean()
    .types(MyService.class)
    .scope(RequestScoped.class)
    .createWith(ctx -> …)
    .name("myservice");
    }
    }
    Add a Bean
    

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33. class ProcessAnnotatedTypeExtension implements Extension {

    void processAnnotatedType(@Observes
    @WithAnnotations(UseCase.class) ProcessAnnotatedType pat) {

    

    pat.configureAnnotatedType()
    .methods() 

    .forEach(m -> m.add(CacheableLiteral.INSTANCE));

    }
    }
    Add annotation to Methods
    

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34. class ProcessAnnotatedTypeExtension implements Extension {

    void processAnnotatedType(@Observes
    @WithAnnotations(UseCase.class) ProcessAnnotatedType pat) {

    

    pat.configureAnnotatedType()
    .methods() 

    .forEach(m -> m.add(CacheableLiteral.INSTANCE));

    }
    }
    Add annotation to Methods
    

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35. AOP on produced Bean
    • CDI 1.0+: Interceptor applied to producer method
    • CDI 2.0: InterceptionFactory
    @Produces 

    @Transactional

    public MyService produceService() {

    ... 

    }
    

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36. AOP on produced Bean
    @Produces

    @RequestScoped

    public MyService createTransactional(InterceptionFactory ify) {

    

    ify.configure()

    .filterMethods(m -> m.getJavaMember().getName().equals("save"))

    .forEach(m -> m.add(new AnnotationLiteral() {}));

    

    return ify.createInterceptionProxy(new MyService());

    }
    

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37. AOP on produced Bean
    @Produces

    @RequestScoped

    public MyService createTransactional(InterceptionFactory ify) {

    

    ify.configure()

    .filterMethods(m -> m.getJavaMember().getName().equals("save"))

    .forEach(m -> m.add(new AnnotationLiteral() {}));

    

    return ify.createInterceptionProxy(new MyService());

    }
    

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38. Proxy matters
    

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39. Proxy injection
    @Inject

    private MyService myService;
    This is a proxy instance
    

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40. Proxy injection
    @Inject
    @Named("myBean")

    private ConcurrentHashMap myService;
    /** Implementation for put and putIfAbsent */

    final V putVal(K key, V value, boolean onlyIfAbsent)
    

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41. Normal-scoped beans
    • Must be proxyable
    • accessible, no-args constructor
    • non-final classes
    • accessible, non-final instance methods
    

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42. Enabling proxying
    @Produces

    @RequestScoped

    public MyService createTransactional(InterceptionFactory ify) {

    

    ify.ignoreFinalMethods();
    

    return ify.createInterceptedInstance(new MyService());

    }
    

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43. Enabling proxying
    @Produces

    @RequestScoped

    public MyService createTransactional(InterceptionFactory ify) {

    

    ify.ignoreFinalMethods();
    

    return ify.createInterceptedInstance(new MyService());

    }
    

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44. Wrap-up
    • Baseline to Java 8, part of Java EE 8
    • Weld 3.0 (May 2017)
    • OpenWebBeans 3.0 (July 2017)
    • Major changes in Java SE, Events, SPI
    

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45. Get in touch
    Slides – Speakerdeck(mp911.de/cdi-20)
    Code: github.com/mp911de/cdi-2.0
    Web: cdi-spec.org
    Mailing list: cdi-dev@lists.jboss.org
    IRC: irc://freenode.net/#cdi-dev
    Twitter: @cdispec // @mp911de
    Github: github.com/cdi-spec
    CDI 2.0 JCP page: jcp.org/en/jsr/summary?id=365
    

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