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2015 JavaOne EJB/CDI Alignment
The document discusses the alignment of EJB and CDI technologies, outlining the historical context and influences on CDI's development. It highlights key changes in Java EE versions, the adoption of CDI by EJB and other technologies, and the challenges faced in achieving full alignment. Additionally, it addresses common mistakes made by developers and the advantages of using CDI, such as its extensibility and open-source nature.
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Similar to 2015 JavaOne EJB/CDI Alignment
2015 JavaOne EJB/CDI Alignment
- 1. JavaOne @dblevins @tomitribe#EJBCDI EJB/CDI Alignment (WhatDoes It Mean?) David Blevins Tomitribe Jean-Louis Monteiro Tomitribe
- 2. JavaOne @dblevins @tomitribe#EJBCDI CDI -EJB Alignment (understand the conversation)
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- 4. JavaOne @dblevins @tomitribe#EJBCDI CDI Influences •Dependency Injection • Definite Spring influence • Strong Google Guice syntax • Originally called “WebBeans” • Grew from Seam • Glued JSF and EJB together
- 5. JavaOne @dblevins @tomitribe#EJBCDI CDI Behindthe Scenes • Achieved through sneaky interceptor trick • Caused major delay to the Java EE 6 delivery • Almost didn’t make it • Criticized for going too far • Stepped on EE toes (spec overlap) • Stepped on SE toes (too “enterprisey”)
- 6. JavaOne @dblevins @tomitribe#EJBCDI CDI Rifts •Creation of @ManagedBean spec at EE level • Fuzzy aim at unifying EE component models • Effort to not lose ground in EE • Too ambiguous • Creation of @Inject spec at SE level • Fuzzy aim at being simpler version of the standard • Effort to not lose ground in SE • Too simple, no spec
- 7. JavaOne @dblevins @tomitribe#EJBCDI EJB Shortcomings •Legacy • Reputation • Fully loaded by default • Every method starts a transaction • Throwing an exception destroys the instance • Instances are non-concurrent
- 8. JavaOne @dblevins @tomitribe#EJBCDI CDI Takeover •EJB adopts CDI (Java EE 6) • JSF adopts CDI (Java EE 7) • MVC adopts CDI (Java EE 8) • JAX-RS considers CDI (Java EE 8) • CDI moves to SE (Java EE 8)
- 9. JavaOne @dblevins @tomitribe#EJBCDI Result forEJB? • Java EE 7 • Focus on realignment: @Transactional • Java EE 8 • First spec round with no new EJB JSR • Realignment stalled • Awkward relationship
- 10. JavaOne @dblevins @tomitribe#EJBCDI CDI froman EJB perspective
- 11. JavaOne @dblevins @tomitribe#EJBCDI Proxy (Fake) Proxy (Fake) Interceptors Decorators Instance (Real) Security Transaction Interceptors Decorators Instance (Real) 1. Resolution 2.Services 3. Invocation (Pool) 1. Resolution 2. Services 3. Invocation (Context/Scope) CDI 1.0 EJB 3.1
- 12. JavaOne @dblevins @tomitribe#EJBCDI Proxy (Fake) Proxy (Fake) Security Transaction Interceptors Decorators Instance (Real) 1. Resolution 2.Services 3. Invocation (Pool) 1. Resolution 2. Services 3. Invocation (Context/Scope) CDI 1.1 EJB 3.2 Transaction Interceptors Decorators Instance (Real)
- 13. JavaOne @dblevins @tomitribe#EJBCDI Lifecycle Lineup •@Singleton • same as CDI @ApplicationScoped • @Stateful • applies to any CDI Scope, not just @SessionScoped • @Stateless • no CDI equivalent • @RequestScoped sort of close(ish)
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- 16. JavaOne @dblevins @tomitribe#EJBCDI Common Mistakesyou will make • Not putting a beans.xml in your app (Java EE 6) • No CDI for you! • Not understanding @Typed • Psst, think @Local from EJB • Bites you when using @Produces • Not understanding what Dependent and NormalScope • Dependent == plain object • NormalScoped == proxied object • Bites you when creating custom scopes
- 17. JavaOne @dblevins @tomitribe#EJBCDI Biggest benefitsof CDI • Very active and open expert group • Fully extendable • Beans can be added at runtime • Fully Open Source • Spec is open source • All implementations are open source • Compliance test (TCK) suite is open source
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- 19. JavaOne @dblevins @tomitribe#EJBCDI Transactions -Aligned • @TransactionAttribute & @ApplicationException • Usable by • @Stateless • @Stateful • @Singleton • @Transactional (CDI equivalent, new in Java EE 7)
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- 22. JavaOne @dblevins @tomitribe#EJBCDI Observations • Pros •New API is Better • Doesn’t say “EJB” • Cons • Duplicating APIs • Slight changes • Conflicting usage?
- 23. JavaOne @dblevins @tomitribe#EJBCDI Observations -What happens? • More work for servers to check for mistakes • More work for IDEs to check for mistakes • New users won’t know which to use and where • Old users won’t remember how they are different • One more place for us all to make mistakes and be confused
- 24. JavaOne @dblevins @tomitribe#EJBCDI When youstill need EJB (not yet aligned)
- 25. JavaOne @dblevins @tomitribe#EJBCDI Security • @RolesAllowed,@PermitAll, @DenyAll • Usable by • @Stateless • @Stateful • @Singleton • Alignment • Low likelihood • Pandora’s box • Not actively being discussed
- 26. JavaOne @dblevins @tomitribe#EJBCDI Startup • @Startup •Eagerly creates the instance upon startup • Usable by • @Singleton • Alignment • Strong Candidate
- 27. JavaOne @dblevins @tomitribe#EJBCDI Asynchronous • @Asynchronsous •Allows method calls to be asynchronous and return Future objects • Usable by • @Stateless • @Stateful • @Singleton • Alignment • Strong Candidate • Tracked in JIRA, high votes
- 28. JavaOne @dblevins @tomitribe#EJBCDI Schedule • @Schedule •Effectively Cron -- schedule invocations by minute or date, etc. • Usable by • @Stateless • @Singleton • Not @Stateful • Alignment • Strong Candidate • Could be a challenge -- timers are stateless, scopes are not
- 29. JavaOne @dblevins @tomitribe#EJBCDI Locking • @Lock(READ)/ @Lock(WRITE) / @AccessTimeout • Allows for synchronization of methods without complex code • Usable by • @Singleton • Not @Stateless • Not @Stateful • Alignment • Medium Candidate • Applying to CDI possibly easier than EJB
- 30. JavaOne @dblevins @tomitribe#EJBCDI MDBs • @MessageDriven •Connector-Driven Beans • Usable by • Not @Singleton • Not @Stateless • Not @Stateful • Alignment • Medium Candidate • Pandora’s Box -- very complicated
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