Winter is coming (Johannes vs Johanes

1. Winter is coming(Johannes vsJohanes Nets DevDay 2012 Johannes Brodwall, Principal Architect Steria Norway @jhannes

2. Whydependencydetox?

3. <?xmlversion="1.0" encoding="UTF-8"?> <beansdefault-autowire="constructor"> <beanclass="no.steria.spring.ApplicationServiceImpl" /> <beanclass="no.steria.spring.IncrementService" /> <beanclass="no.steria.spring.ReportService" /> <beanclass="no.steria.winterapp.provided.JdbcEntryDao" /> <beanclass="org.springframework.jndi.JndiObjectFactoryBean"> <property name="jndiName" value="jdbc/primaryDs" /> </bean> </beans>

4. publicstaticvoid main(String[] args){ ApplicationContextcontext = newClassPathXmlApplicationContext("..."); ApplicationServiceapplicationService=context.getBean(ApplicationService.class); applicationService.incrementAndReport(new Date()); }

5. In what <import> is that bean defined? Who created that object? Is that setter still in use? The “Service” here does nothing! Where is the business logic?! Are we sure @Transactional is picked up? How does @Transaction work?!

6. Less magic

7. publicstaticvoid main(String[] args) { ApplicationServiceapplicationService = newApplicationService(createDataSource()); applicationService.incrementAndReport(newDate()); }

8. Explicitcoupling

9. publicclassApplicationService { privateIncrementServiceincrementService; privateReportServicereportService; publicApplicationService(DataSourcedataSource) { this(newIncrementService(dataSource), newReportService(dataSource)); } publicApplicationService(IncrementServiceincrementSvc,ReportServicereportSvc) { this.incrementService = incrementService; this.reportService = reportService; } publicvoidincrementAndReport(Date date) { incrementService.increment(date); reportService.printReport(); } }

10. publicclassIncrementService { privateEntryDaoentryDao; publicIncrementService(DataSourcedataSource) { this(newJdbcEntryDao(dataSource)); } publicIncrementService(EntryDaoentryDao) { this.entryDao = entryDao; } publicvoidincrement(Date date) { entryDao.insertEntry(newEntry(date)); } }

11. Better quality Less searching Compiler errors

12. ”You know you are working on clean code when each routine you read turns out to be pretty much what you expected.” Ward Cunningham:

13. Whence Spring framework?

14. EJB 2.0 … reallysucked … onefeature: Transactions!

15. Java design in 2003 … reallysucked … Singleton craze … neededdependencycontrol … needed more magic

16. What’s relevant today?

17. EJB 2.0 … um… no!

18. Transactions … it’sreally not that hard! … let me show you

19. publicinterfaceTransactionManager { TransactionbeginTransaction(); } publicinterfaceTransactionextendsCloseable { voidsetCommit(); voidclose(); }

20. @Test publicvoidrollbackTransaction() throws Exception { doThrow(newRuntimeException()).when(targetObject).doIt(); try { transactional(targetObject).doIt(); fail("Shouldthrowexception"); } catch (RuntimeException e) { // expected } verify(tx, never()).setCommit(); verify(tx).close(); }

21. protected<T> T transactional(final T targetObject) { returnProxy.newProxyInstance(getClass().getClassLoader(), …, newInvocationHandler() { @Override public Object invoke(…, Method method, Object[] args) { Transactiontransaction = txMgr.beginTransaction(); try { method.invoke(targetObject, args); transaction.setCommit(); } finally { transaction.close(); } returnnull; } }); } Since Java 1.4!

22. voidinTx(ExampleInterfacetargetObject) { try (Transactiontx = txMgr.beginTransaction()) { targetObject.doIt(); // if doIt() throws, we never get here // – then close() rolls back tx.setCommit(); } } Java 1.7

23. Dependency management … Goingwaaaay over board

24. Person-Controller Person-Service Person-Repository PersonDao Person-Controller-Impl Person-ServiceImpl Person-Repository Impl PersonDao Impl Session-Factory

26. Customer Invoice Order Product

27. How many real configured things do we have?

28. <?xmlversion="1.0" encoding="UTF-8"?> <beansdefault-autowire="constructor"> <beanclass="no.steria.spring.ApplicationServiceImpl" /> <beanclass="no.steria.spring.IncrementService" /> <beanclass="no.steria.spring.ReportService" /> <beanclass="no.steria.winterapp.provided.JdbcEntryDao" /> <beanclass="org.springframework.jndi.JndiObjectFactoryBean"> <property name="jndiName" value="jdbc/primaryDs" /> </bean> </beans>

29. DataSource (Other resources) Hibernate SessionFactory Web Services (URLs)

30. Varying for tests

31. For test publicclassPersonServletextendsHttpServlet { privatePersonDaopersonDao; publicvoidsetPersonDao(PersonDaopersonDao) { this.personDao = personDao; } @Override publicvoidinit() throwsServletException { setPersonDao(newHibernatePersonDao("jdbc/personDs")); } } New? Wut?!?! For realz

32. Hmmm… publicclassHibernatePersonDaoimplementsPersonDao { publicHibernatePersonDao(StringjndiDataSource) { Configurationcfg = newConfiguration(); cfg.setProperty(Environment.DATASOURCE, jndiDataSource); …; cfg.addAnnotatedClass(Person.class); this.sessionFactory = cfg.buildSessionFactory(); } Hmmm…

33. publicclassPersonServletextendsHttpServlet { privatePersonDaopersonDao; publicvoidsetPersonDao(PersonDaopersonDao) { this.personDao = personDao; } @Override publicvoidinit() throwsServletException { setPersonDao(HibernatePersonDao.getInstance()); } } Singleton FTW!

34. Announcing A Powerful New Framework: Programming Language is a powerful new framework that enables developers to quickly and easily handle Dependency Injection, Inversion of Control, Model-View-Controller and many other common design problems. Jason Gorman http://codemanship.co.uk/parlezuml/blog/?postid=1097

35. Intermezzo

37. Whichone is right?

39. Messy picture Well-architected picture

41. com.app.person OR com.app.controller

42. Now… aboutdependencyinjection

44. Don’t inject hard stuff

45. PersonController Service Repository Session-Factory

46. Hard stuff publicclassPersonController { privatePersonServicepersonService; @Autowired publicPersonController(SessionFactorysf) { this.personService = newPersonServiceImpl(sf); } publicclassPersonServiceImplimplements … { privatePersonRepositorypersonRepo; publicPersonServiceImpl(SessionFactorysf) { this.personRepo = newPersonRepositoryImpl(sf); } Hard stuff

47. For Spring publicclassPersonController { privatePersonServicepersonService; @Autowired publicPersonController(SessionFactorysf) { this.personService = newPersonServiceImpl(sf); } publicPersonControllerImpl(PersonServiceps) { this.personService = ps; } For mocking

48. SPRING! PersonController Service Repository InvoiceController Service Repository Session-Factory ReportsController FooController FooServiceImpl

49. Collapse service chains

50. SPRING! PersonController Service Repository InvoiceController Repository Session-Factory ReportsController FooController FooServiceImpl