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
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
3. CanDI
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
5. @ApplicationScoped class UserService { User createUser() { return …; } } class UserServlet extends HttpServlet { @Inject UserService service; }
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(); } }
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
8. Java SE
9. Java SE • Currently: Implementation-specific in Weld/ OpenWebBean • Spec Goal: Bootstrap API
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();
 }
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();
 }
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();
 }
13. Events
14. @Observes
15. @Priority
16. Ordered Events • Add @Priority to event observers • Aids observer ordering • Total global order determined when the event is fired
17. Observer Ordering public void observer(@Observes @Priority(2500) MyEvent event) {
 System.out.println("Default priority");
 }
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");
 }
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");
 }
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");
 }
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");
 }
22. @ObservesAsync
23. Asynchronous Events • Notify event observers asynchronously • One or more different threads • Decoupled from synchronous events
24. Firing Async Events @Inject
 private Event<MyEventPayload> event;
 public void triggerEvent() {
 event.fireAsync(new MyEventPayload());
 }
25. Firing Async Events @Inject
 private Event<MyEventPayload> event;
 public void triggerEvent() {
 event.fireAsync(new MyEventPayload());
 }
26. Observing Async Events public void observer(@ObservesAsync MyEvent payload) {
 System.out.println("Yay, I'm called async!");
 }
27. How it works @Observes @ObservesAsync event.fire(…) Sync call Not notified event.fireAsync(…) Not notified Async call
28. Asynchronous Events • Exceptions and Synchronization with CompletionStage • Active scopes: Request, Application • Custom scopes depend on the implementation
29. Portable Extensions
30. Meta-Data Builder API • Standardized API • CDI 1.0+: Very verbose to create • AnnotatedTypes, Beans, BeanAttributes, InjectionPoints, and ObserverMethods • Builder and Configurator-style
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
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
33. class ProcessAnnotatedTypeExtension implements Extension {
 <T> void processAnnotatedType(@Observes @WithAnnotations(UseCase.class) ProcessAnnotatedType<T> pat) {
 
 pat.configureAnnotatedType() .methods() 
 .forEach(m -> m.add(CacheableLiteral.INSTANCE));
 } } Add annotation to Methods
34. class ProcessAnnotatedTypeExtension implements Extension {
 <T> void processAnnotatedType(@Observes @WithAnnotations(UseCase.class) ProcessAnnotatedType<T> pat) {
 
 pat.configureAnnotatedType() .methods() 
 .forEach(m -> m.add(CacheableLiteral.INSTANCE));
 } } Add annotation to Methods
35. AOP on produced Bean • CDI 1.0+: Interceptor applied to producer method • CDI 2.0: InterceptionFactory @Produces 
 @Transactional
 public MyService produceService() {
 ... 
 }
36. AOP on produced Bean @Produces
 @RequestScoped
 public MyService createTransactional(InterceptionFactory<MyService> ify) {
 
 ify.configure()
 .filterMethods(m -> m.getJavaMember().getName().equals("save"))
 .forEach(m -> m.add(new AnnotationLiteral<Transactional>() {}));
 
 return ify.createInterceptionProxy(new MyService());
 }
37. AOP on produced Bean @Produces
 @RequestScoped
 public MyService createTransactional(InterceptionFactory<MyService> ify) {
 
 ify.configure()
 .filterMethods(m -> m.getJavaMember().getName().equals("save"))
 .forEach(m -> m.add(new AnnotationLiteral<Transactional>() {}));
 
 return ify.createInterceptionProxy(new MyService());
 }
38. Proxy matters
39. Proxy injection @Inject
 private MyService myService; This is a proxy instance
40. Proxy injection @Inject @Named("myBean")
 private ConcurrentHashMap<String, String> myService; /** Implementation for put and putIfAbsent */
 final V putVal(K key, V value, boolean onlyIfAbsent)
41. Normal-scoped beans • Must be proxyable • accessible, no-args constructor • non-final classes • accessible, non-final instance methods
42. Enabling proxying @Produces
 @RequestScoped
 public MyService createTransactional(InterceptionFactory<MyService> ify) {
 
 ify.ignoreFinalMethods(); 
 return ify.createInterceptedInstance(new MyService());
 }
43. Enabling proxying @Produces
 @RequestScoped
 public MyService createTransactional(InterceptionFactory<MyService> ify) {
 
 ify.ignoreFinalMethods(); 
 return ify.createInterceptedInstance(new MyService());
 }
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
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