![“Undo” aware Resources
• DataSource
• EntityManager
• Sending JMS Messages
• Receiving JMS Messages
• Timers & @Schedule
• (more via Java EE connectors)
[Some restrictions apply. Offer void where prohibited. Container-
provided resources required. Must be 18 years or older to apply]](https://image.slidesharecdn.com/2012jaxconftomcattojavaeewithtomee-120817035711-phpapp02/85/From-Tomcat-to-Java-EE-making-the-transition-with-TomEE-26-320.jpg)
From Tomcat to Java EE, making the transition with TomEE
- 1. David Blevins | Apache Tomcat to JavaEE with Apache TomEE
- 3. What is Apache TomEE?
- 4. Tomcat + JavaEE = TomEE • Java EE 6 Web Profile certified • Tomcat through and through • All Apache components – OpenJPA – OpenWebBeans – OpenEJB – MyFaces • Core Values – Be small – Be certified – Be Tomcat
- 5. Flavors of TomEE • Apache TomEE Web Profile (Java EE 6 Certified) – CDI – EJB – JPA – JSF – Bean Validation • Apache TomEE Plus – JAX-RS – JAX-WS – JMS • Embedded Apache TomEE
- 6. Basic Stats • Size – 27mb • Memory usage – very little required – passes TCK with default 64mb • Agility: – Eclipse deploy ~700ms – embedded test 2-4 seconds
- 7. Certification • Certified on Amazon EC2 – t1.micro linux images, – 100 spot instances – 613mb memory – 64mb used, 549mb free – t1.micros have slow disks, memory is critical • Current certified OSs – Amazon Linux AMI 2011.09, EBS boot, EC2 t1.micro – Amazon Linux AMI 2011.09, EBS boot, EC2 m1.small – Amazon Linux AMI 2011.09, EBS boot, EC2 c1.medium • Runs daily • Got a Cloud? – Donate time!
- 8. “There is also one point to note. TomEE is insanely fast! ” -- Łukasz Budnik, CXF JAX-RS on Apache TomEE @ DZone, May 23rd 2012 “From an architect that switched from <XXX> to Tomee. I can tell you Tomee kicks <XXX>'s ass in every way. Memory, speed, reliability, validation, you name it.” -- Zeeman, User List, July 3rd 2012 “If you are concerned about performance and footprint, but can accept that you'll have to solve problems yourself, go TomEE. (TomEE seems to be _much_ faster than <XXX>)” -- Jonathan Fisher, User List, July 3rd 2012
- 10. Gaps in Tomcat • No Transaction support • No Connection Pooling support – Pooling should be transactional • No Integrated Security • No support for Global JNDI – java:module – java:app – java:global • No support for @DataSourceDefinition • No support for new <env-entry> types: – java.lang.Class – Enums
- 11. Gaps in Tomcat • No @Resource – UserTransaction – BeanManager – Validator – ValidatorFactory – Topic/Queue – ConnectionFactory • No @PersistenceUnit • No @PersistenceContext • No @Inject • No @EJB • No @WebServiceRef
- 12. Migration Issues
- 13. Building your own app server • Including API jars in the webapp – JPA API – JSF API – etc. • Including implementations in webapp – Mojarra (works in trunk) – Bitronix/Atomikos • Non-compliant DataSource and JPA – too many years of Do It Yourself – providers not enforcing rules
- 14. (Mis)Information • Gaps in Knowledge – “that other stuff” • Misinformation – don’t use X, it’s heavy • Leads to... – let’s build own own heavy X! • Bites you – non-portable apps – lacks tens of thousands of tests – lacks shared experience
- 15. Closing Gaps in Knowledge
- 16. You can’t use this • unless you understand – JTA Transactions – Container-managed EntityManagers – Container-managed DataSources – How to get references to these, properly!
- 17. Not Just EJBs • Components with Transaction support – Servlets – JSP – JSF Managed Beans – CDI – EJB – JAX-RS REST Services – JAX-WS Web Services
- 19. “Undo”
- 23. Controlling Transactions • javax.transaction.UserTransaction – Manual approach – Any JavaEE component • @javax.ejb.TransactionAttribute – Class or method annotation – EJB only • @javax.transaction.Transactional – Class or method annotation – Any JavaEE component* – Coming in JavaEE 7
- 24. Transaction Hooks • SessionSynchronization – @AfterBegin – @BeforeCompletion – @AfterCompletion • Events – @Observes(during=IN_PROGRESS) – @Observes(during=BEFORE_COMPLETION) – @Observes(during=AFTER_COMPLETION) • @Observes(during=AFTER_SUCCESS) • @Observes(during=AFTER_FAILURE)
- 26. “Undo” aware Resources • DataSource • EntityManager • Sending JMS Messages • Receiving JMS Messages • Timers & @Schedule • (more via Java EE connectors) [Some restrictions apply. Offer void where prohibited. Container- provided resources required. Must be 18 years or older to apply]
- 28. How does it work?
- 29. TOP SECRET (authorized personnel only)
- 30. This is not a pipe
- 31. Not the real thing
- 32. The EntityManager You Get
- 34. continued...
- 35. The DataSource You Get
- 37. better than a pipe
- 38. ...better than the real thing • thread-safe • undo-aware • leak-free
- 39. All boils down to...
- 41. ...but
- 42. Won’t work with any of this • DataSource – DriverManager.getConnection(...) – new FooDataSource() – autocommit = true • EntityManager – PersistenceProvider.createEntityManag... – EntityManagerFactory.createEntityManager – EntityTransaction
- 43. Avoid Do It Yourself
- 44. Rule • If you didn’t get it from the Container – it isn’t usable with UserTransaction – connections may leak – memory may leak • Even then there are some BIG notes – EntityManagerFactory • not usable with UserTransaction – <persistence-unit=RESOURCE_LOCAL> • not usable with UserTransaction
- 46. Common Migration Issues & Mistakes
- 47. Wrong
- 48. Wrong
- 49. Wrong
- 50. Still Wrong
- 52. The worst of them all
- 53. this...
- 54. or this...
- 55. with THIS!
- 56. darn defaults!
- 57. There we go
- 58. JPA Rules • RESOURCE_LOCAL – Persistence.createEntityManagerFactory – @PersistenceUnit EntityManagerFactory – <non-jta-data-source> • JTA – @PersistenceContext EntityManager – <jta-data-source> – <non-jta-data-source> • No other combinations are valid
- 59. Good • Valid RESOURCE_LOCAL usage
- 60. Better • Valid RESOURCE_LOCAL usage
- 61. Best • Valid JTA usage
- 62. DataSource • Declare – in tomee.xml – in META-INF/resources.xml – via @DataSourceDefinition • Retrieve – @Resource – <resource-ref> • Undo-aware and pooled
- 64. Recap
- 65. Recap • Use if you need “undo” • Transactions not heavy – Thread safe management – Help prevent Leaks – Enhance programming • More than a TransactionManager – TransactionManagers do nothing alone – Resources must cooperate • Don’t Do It Yourself – Use container-provided resources – no need to re-invent the wheel
- 66. Recap • Components with Transaction support – Servlets – JSP – JSF Managed Beans – CDI – EJB – JAX-RS REST Services – JAX-WS Web Services
- 67. Recap • Transactional Resources – DataSource – EntityManager – Sending JMS Messages – Receiving JMS Messages – Timers & @Schedule – (more via Java EE connectors)
- 68. Questions?
- 69. Thank You! @dblevins http://tomee.apache.org