CDI 2.0 Deep Dive
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The document discusses plans for Contexts and Dependency Injection (CDI) 2.0. Main topics for CDI 2.0 include improving the event system by adding support for asynchronous events and event ordering. It also aims to define bootstrapping for CDI in Java SE applications and improve aspects of CDI like AOP. The specification work incorporates community feedback and aims to support new Java 8 features.
CDI 2.0 Deep Dive
- 1. CDI 2.0 Deep Dive
- 2. MarkStruberg • Member Apache Software Foundation • VP, Apache OpenWebBeans • CDI expert group member • Twitter: @struberg • Blog: struberg.wordpress.com @struberg @thjanssen123CDI 2.0 Deep Dive
- 3. ThorbenJanssen • Independent author and trainer • Senior developer and architect @ Qualitype GmbH • CDI 2.0 expert group member • Twitter: @thjanssen123 • Blog: www.thoughts-on-java.org @struberg @thjanssen123CDI 2.0 Deep Dive
- 4. CDI? What‘s that? @struberg @thjanssen123CDI 2.0 Deep Dive
- 5. WhatisCDI? • Contexts and Dependency Injection for JavaTM 2.0 (JSR 365) • Provides • Contexts • Dependency Injection • Events • Interceptors and decorators • Extensions @struberg @thjanssen123CDI 2.0 Deep Dive
- 6. HistoryofCDI • CDI 1.0 (Java EE 6) December 2009 • CDI 1.1 (Java EE 7) June 2013 • CDI 1.2 April 2014 • CDI 2.0 Start September 2014 • CDI 2.0 Early Draft Release 2015 • CDI 2.0 Release 1st half of 2016 • CDI 2.1 Start after 2.0 Release @struberg @thjanssen123CDI 2.0 Deep Dive
- 7. CDI 2.0 @struberg @thjanssen123CDI 2.0 Deep Dive
- 8. CDI2.0 • Work on CDI 2.0 is still in progress • No final decision yet • Everything might change @struberg @thjanssen123CDI 2.0 Deep Dive
- 9. MainTopics • Improve the event system • Bootstrapping for Java SE • Modularity • Improve AOP • Enhance SPI and Contexts • Support Java 8 features @struberg @thjanssen123CDI 2.0 Deep Dive
- 10. MainTopics • Defined by • Existing entries in Jira • Requirements by other specs • Input from former expert group members • Community survey @struberg @thjanssen123CDI 2.0 Deep Dive
- 11. CommunitySurvey • June 2014 • 260 participants • 20 features to rate • Asynchronous events • Bootstrapping outside of Java EE • AOP for produced or custom beans • Observer ordering @struberg @thjanssen123CDI 2.0 Deep Dive
- 12. Events @struberg @thjanssen123CDI 2.0 Deep Dive
- 13. Events • One of the bigger topics in CDI 2.0 • High demand by community • Features • Asynchronous events • Ordering of events @struberg @thjanssen123CDI 2.0 Deep Dive
- 14. SynchronousEvents • Fire a synchronous event @Inject Event<UserEvent> userEvent; … userEvent.fire (new UserEvent(…)); • Observe a synchronous event public void handleUserEvent(@Observes UserEvent e) {…} @struberg @thjanssen123CDI 2.0 Deep Dive
- 15. AsynchronousEvents • Fire an asynchronous event @Inject Event<UserEvent> userEvent; … userEvent.fireAsync(new UserEvent(…)); • Observe an asynchronous event public void handleUserEvent(@ObserveAsync UserEvent e) {…} @struberg @thjanssen123CDI 2.0 Deep Dive
- 16. AsynchronousEvents • Result and exception handling event.fireAsync(new UserEvent(…)) .whenComplete((event, throwable) -> { if (throwable != null) { logger.error(“Error during processing of UserEvent” + throwable.getMessage()); } else { logger.info(“Processing successful”); } }); @struberg @thjanssen123CDI 2.0 Deep Dive
- 17. AsynchronousEvents • What could possibly go wrong? • Thread executor group might get blocked by slow observers • Mutable non-threadsafe payload e.g. visitor pattern with ArrayList in event payload • @SessionScoped doesn‘t get propagated between threads • @RequestScoped doesn‘t get propagated between threads e.g. @Inject Principal currentUser @struberg @thjanssen123CDI 2.0 Deep Dive
- 18. AsynchronousEvents • What could possibly go wrong? • ThreadLocals of all kind don‘t get propagated e.g. log4j MappedDiagnosticContext • Transactions don‘t get propagated TransactionSynchronisationRegistry is basically a ThreadLocal • New EntityManager and @PersistenceContext for each thread • @Observes(during=TransactionPhase.AFTER_SUCCESS) • Each async observer gets ist own transaction! @struberg @thjanssen123CDI 2.0 Deep Dive
- 19. AsynchronousEvents • All these problems are caused by multi-threading behavior in Java EE and not CDI specific • Very same problems occure with EJB @Asynchronous and Concurrency-Utils for Java EE @struberg @thjanssen123CDI 2.0 Deep Dive
- 20. AsynchronousEvents • Introduces new, asynchronous kind of events • CompletionStage<U> fireAsync(U event) • @ObservesAsync Event method @Observes notified @ObservesAsync notified fire() Yes No fireAsync() No Yes @struberg @thjanssen123CDI 2.0 Deep Dive
- 21. OrderingofEvents • Define the order of event observers public void handleUserEvent( @Observe @Priority(1000) UserEvent e) {…} • Call smallest priority first • Uses default priority if not defined • Order undefined for Observer with same priority @struberg @thjanssen123CDI 2.0 Deep Dive
- 22. Bootstrapping @struberg @thjanssen123CDI 2.0 Deep Dive
- 23. Bootstrapping • Define a standard way to boot the CDI container in Java SE • Already part of Weld and Open Web Beans • First API proposed in EDR 1 @struberg @thjanssen123CDI 2.0 Deep Dive
- 24. Bootstrapping • API proposal in EDR1 public static void main(String... args) { try(CDI<Object> cdi = CDI.getCDIProvider().initialize()) { // start the container, // retrieve a bean and do work with it MyBean myBean = cdi.select(MyBean.class).get(); myBean.doWork(); } // shuts down automatically after // the try with resources block. } https://docs.jboss.org/cdi/spec/2.0.EDR1/cdi-spec.html#bootstrap- se @struberg @thjanssen123CDI 2.0 Deep Dive
- 25. Bootstrapping • API currently under discussion • Context control not defined yet • Bean discovery mode still under discussion • Provide an option to choose implementation @struberg @thjanssen123CDI 2.0 Deep Dive
- 26. CdiCtrlCdiContainer • Allows to boot embedded EE containers with a vendor independent API • Implementations for: • Apache OpenWebBeans • JBoss Weld • JBoss WildFly in the making • Apache OpenEJB (TomEE embedded) • add your own • Simply replace the impl jar to switch! @struberg @thjanssen123CDI 2.0 Deep Dive
- 27. CdiCtrl-ContainerBootstrap • Very usable for unit tests, batches or other standalone Java processes: CdiContainer cdiContainer = CdiContainerLoader.getCdiContainer(); cdiContainer.boot(); cdiContainer.getContextControl().startContexts(); … cdiContainer.shutdown(); @struberg @thjanssen123CDI 2.0 Deep Dive
- 28. CdiCtrl-ContextControl • Also usable in EE containers • Usage: @Inject ContextControl ctxCtrl; • Allows to attach dummy RequestContext, SessionContext etc to the current Thread. • Usable for Quartz extensions or any other async work @struberg @thjanssen123CDI 2.0 Deep Dive
- 29. AOP @struberg @thjanssen123CDI 2.0 Deep Dive
- 30. AOP • Work on AOP improvements just started • Topics • Improve handling of UnproxyableResolutionException • Interceptors and Decorators on produced and custom beans • Support AOP on inner calls @struberg @thjanssen123CDI 2.0 Deep Dive
- 31. ClassProxies • No Java SE support so far! • All done in a container depending own way • Most times uses bytecode libraries like javassist, ASM, cglib, bcel or serp • Create a sub-class of the given type • Override all public methods @struberg @thjanssen123CDI 2.0 Deep Dive
- 32. UnproxyAble? • CDI throws an UnproxyAbleResolutionException for all classes which have • No default constructor • final, non-static and non-private methods e.g. ConcurrentHashMap www.thoughts-on-java.org
- 33. SubclassProxyExample1/2 • The business class @SessionScoped public class User { private String name; public String getName() { return name; } } @struberg @thjanssen123CDI 2.0 Deep Dive
- 34. SubclassProxyExample2/2 public class User$$Proxy extends User { @Override public String getName() { return getInstance().getName(); } private T getInstance() { beanManager.getContext().get(...); } } @struberg @thjanssen123CDI 2.0 Deep Dive
- 35. AllowProxying • Proposed solution • Annotation @AllowProxying • beans.xml <allowProxying> @struberg @thjanssen123CDI 2.0 Deep Dive
- 36. AllowProxying • Proposed solution 1 • Annotation @AllowProxying Public class Owner { @Produces @RequestScoped @TenantA @AllowProxying ConcurrentHashMap createConfigBase() {…} } @struberg @thjanssen123CDI 2.0 Deep Dive
- 37. AllowProxying • Proposed solution • beans.xml <allowProxying> <allowProxying> <class>java.util.concurrent.ConcurrentHashMap</class> </allowProxying> @struberg @thjanssen123CDI 2.0 Deep Dive
- 38. InterceptorsonProducers • Long discussions… • Probably solvable by introducing javax.proxy.ProxyFactory? • Like java.lang.reflect.Proxy but with subclassing see DeltaSpike PartialBean @struberg @thjanssen123CDI 2.0 Deep Dive
- 39. Java 8 @struberg @thjanssen123CDI 2.0 Deep Dive
- 40. Java8 • Java 8 was released after Java EE 7 • Support for Java 8 features • All new APIs will use Java 8 • Changes of existing APIs are still under discussion @struberg @thjanssen123CDI 2.0 Deep Dive
- 41. Java8 • Asynchronous events fireAsync methods return new CompletionStage public <U extends T> CompletionStage<U> fireAsync(U event); public <U extends T> CompletionStage<U> fireAsync(U event, Executor executor); @struberg @thjanssen123CDI 2.0 Deep Dive
- 42. Java8 • Repeatable qualifiers and interceptor bindings • Proposed by RI Weld, not specified so far @Produces @Language(„english“) @Language(„german“) public Translator createTranslator() { … } @struberg @thjanssen123CDI 2.0 Deep Dive
- 43. Get in touch @struberg @thjanssen123CDI 2.0 Deep Dive
- 44. Getintouch • Website: http://www.cdi-spec.org • Blog: http://www.cdi-spec.org/news/ • Twitter: @cdispec • Mailing list: https://lists.jboss.org/mailman/listinfo/cdi-dev • JIRA: https://issues.jboss.org/ @struberg @thjanssen123CDI 2.0 Deep Dive
- 45. Getintouch Mark Struberg Twitter: @struberg Blog: struberg.wordpress.com Thorben Janssen Twitter: @thjanssen123 Blog: www.thoughts-on-java.org @struberg @thjanssen123CDI 2.0 Deep Dive
- 46. Resources • CDI website: http://www.cdi-spec.org • JSR 365 – CDI 2.0: https://jcp.org/en/jsr/detail?id=365 • CDI 2.0 EDR1: https://docs.jboss.org/cdi/spec/2.0.EDR1/cdi-spec.html • The path to CDI 2.0 by Antoine Sabot-Durand: https://www.youtube.com/watch?v=RynnZPsQdxM http://de.slideshare.net/antoinesd/the-path-to-cdi-20 • Blog Weld – CDI reference implementation: http://weld.cdi-spec.org/news/ • Apache OpenWebBeans: http://openwebbeans.apache.org @struberg @thjanssen123CDI 2.0 Deep Dive