Talk on using Spring in Grails given at SpringOne 2GX and the Groovy & Grails Exchange in 2012

1. Under the Hood: Using Spring in Grails
Burt Beckwith
SpringSource
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© 2010 SpringSource, A division of VMware. All rights reserved

2. Who Am I
Java developer for over 13 years
Background in Spring, Hibernate, Spring Security
Grails developer for 5 years
SpringSource employee on the Grails team
Created or reworked over 40 Grails plugins
http://burtbeckwith.com/blog/
https://twitter.com/#!/burtbeckwith
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3. Spring Overview
 Main functions of Spring
• Bean container: ApplicationContext and BeanFactory
• Dependency Injection (DI) and Inversion of Control (IoC)
• Proxies
• Transactions
• Security
• Caching
• Event publishing and listening
• Exception conversion
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4. Grails Services
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5. Grails Services
 What is a Grails Service?
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6. Grails Services
 What is a Grails Service?
• Groovy class in grails­app/services
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7. Grails Services
 What is a Grails Service?
• Groovy class in grails­app/services
• Great place for business logic
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8. Grails Services
 What is a Grails Service?
• Groovy class in grails­app/services
• Great place for business logic
• A Spring bean, by default singleton scope
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9. Grails Services
 What is a Grails Service?
• Groovy class in grails­app/services
• Great place for business logic
• A Spring bean, by default singleton scope
• Automatically transactional unless configured otherwise
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10. Grails Services
 What is a Grails Service?
• Groovy class in grails­app/services
• Great place for business logic
• A Spring bean, by default singleton scope
• Automatically transactional unless configured otherwise
• Proxied, sometimes multiple times
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11. Manually Wiring
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12. Grails Services
src/java/test/UserManager.java
package test;
import other.LoggingService;
import auth.User;
public class UserManager {
private LoggingService loggingService;
public void setLoggingService(LoggingService service) {
loggingService = service;
}
public User createUser(String username) {
User user = new User();
user.setUsername(username);
user.save();
loggingService.logMessage(
"Created user with username " + username);
return user;
}
}
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13. Grails Services
grails-app/conf/spring/resources.groovy
import test.UserManager
beans = {
userService(UserManager) {
loggingService = ref('loggingService')
}
}
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14. Grails Services
grails-app/conf/spring/resources.groovy
import test.UserManager
beans = {
userService(UserManager) { bean ->
bean.autowire = 'byName'
}
}
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15. How to Make it Transactional?
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16. Grails Services
grails-app/conf/spring/resources.groovy
import org.codehaus.groovy.grails.orm.support.GroovyAwareNamedTransactionAttributeSource
import org.springframework.transaction.interceptor.TransactionProxyFactoryBean
import test.UserManager
beans = {
userService(TransactionProxyFactoryBean) { bean ->
bean.lazyInit = true
target = { innerBean ->
innerBean.lazyInit = true
innerBean.autowire = 'byName'
innerBean.beanClass = UserManager
}
proxyTargetClass = true
def props = ['*': 'PROPAGATION_REQUIRED'] as Properties
TransactionAttributeSource =
new GroovyAwareNamedTransactionAttributeSource(transactionalAttributes: props)
transactionManager = ref('transactionManager')
}
}
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17. or
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18. Grails Services
src/java/test/UserManager.java
package test;
import org.springframework.transaction.annotation.Transactional;
import other.LoggingService;
import auth.User;
@Transactional
public class UserManager {
private LoggingService loggingService;
public void setLoggingService(LoggingService service) {
loggingService = service;
}
public User createUser(String username) {
...
}
}
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19. Grails Services
grails-app/conf/spring/resources.groovy
import test.UserManager
beans = {
userService(UserManager) { bean ->
bean.lazyInit = true
bean.autowire = 'byName'
}
}
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20. How to be sure it's
Transactional?
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21. Grails Services
src/java/test/UserManager.java
package test;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.interceptor.TransactionAspectSupport;
import org.springframework.transaction.support.TransactionSynchronizationManager;
...
public User createUser(String username) {
if (TransactionSynchronizationManager.isSynchronizationActive()) {
TransactionStatus status = TransactionAspectSupport.currentTransactionStatus();
System.out.println("TX is active; isRollbackOnly: " + status.isRollbackOnly());
}
else {
System.out.println("Uh-oh, TX not active");
}
...
}
}
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22. Grails Services
grails-app/services/test/UserService.groovy
package test
import auth.User
class UserService {
def loggingService
User createUser(String username) {
def user = new User(username: username)
user.save()
loggingService.logMessage(
"Created user with username $username")
user
}
}
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23. Transaction Helper Methods
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24. Utility Methods
import o.s.t.interceptor.TransactionAspectSupport
import o.s.t.support.TransactionSynchronizationManager
for (sc in grailsApplication.serviceClasses) {
def metaClass = sc.clazz.metaClass
…
}
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25. Utility Methods
// returns TransactionStatus
metaClass.getCurrentTransactionStatus = { ­>
if (!delegate.isTransactionActive()) {
return null
}
TransactionAspectSupport.currentTransactionStatus()
}
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26. Utility Methods
// void, throws NoTransactionException
metaClass.setRollbackOnly = { ­>
TransactionAspectSupport.currentTransactionStatus()
.setRollbackOnly()
}
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27. Utility Methods
// returns boolean
metaClass.isRollbackOnly = { ­>
if (!delegate.isTransactionActive()) {
return false
}
delegate.getCurrentTransactionStatus().isRollbackOnly()
}
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28. Utility Methods
// returns boolean
metaClass.isTransactionActive = { ­>
TransactionSynchronizationManager
.isSynchronizationActive()
}
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29. Dependency Injection
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30. Inversion of Control and Dependency Injection
def userService
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31. Inversion of Control and Dependency Injection
def userService
private Object userService
void setUserService(Object userService) {
this.userService = userService
}
Object getUserService() {
return userService
}
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32. Complex dependency
configuration using Spring
SpEL
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33. Complex dependency configuration using Spring SpEL
beans = {
bar(Bar)
foo(Foo) {
name = '#{bar.name}'
}
}
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34. Complex dependency configuration using Spring SpEL
beans = {
bar(Bar)
foo(Foo) {
name = '#{bar.resourceName()}'
}
}
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35. Manually injecting
dependencies at runtime
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36. Manually injecting dependencies at runtime
import org.springframework.beans.factory.config.AutowireCapableBeanFactory
...
def grailsApplication
...
def instance = new XXX(...)
def ctx = grailsApplication.mainContext
ctx.beanFactory.autowireBeanProperties(
instance,
AutowireCapableBeanFactory.AUTOWIRE_BY_NAME,
false)
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37. Bean Scopes
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38. Bean Scopes
 By default Spring beans are singletons
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39. Bean Scopes
 Other scopes
• prototype
• session
• request
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40. Bean Scopes
 You can even create your own custom scope:
• implement
org.springframework.beans.factory.config.Scope
• register: ctx.beanFactory.registerScope
'myScope', new MyScope()
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41. Bean lifecycles and interfaces
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42. Bean lifecycles and interfaces
 Set the initMethod and/or the destroyMethod names
when registering beans
import com.mycompany.myapp.LdapAuthenticationManager
...
authenticationManager(LdapAuthenticationManager) { bean ­>
serverUrl = '...'
password = '...'
bean.initMethod = 'init'
bean.destroyMethod = 'destroy'
}
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43. Bean lifecycles and interfaces
 Implement the
org.springframework.beans.factory.InitializingBean
interface and its afterPropertiesSet method and/or the
org.springframework.beans.factory.DisposableBean
interface and its destroy method
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44. Bean lifecycles and interfaces
package com.mycompany.myapp
import org.springframework.beans.factory.DisposableBean
import org.springframework.beans.factory.InitializingBean
class LdapAuthenticationManager implements
InitializingBean, DisposableBean {
...
void afterPropertiesSet() {
// initialization work
}
void destroy() {
// shutdown work
}
}
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45. Bean PostProcessors
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46. Bean PostProcessors
 o.s.b.factory.config.BeanPostProcessor
• Object postProcessBeforeInitialization(Object bean,
String beanName)
• Object postProcessAfterInitialization(Object bean,
String beanName)
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47. Bean PostProcessors
 o.s.b.factory.config.BeanFactoryPostProcessor
• void postProcessBeanFactory(ConfigurableListableBeanFactory
beanFactory)
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48. Bean PostProcessors
 o.s.b.factory.support.BeanDefinitionRegistryPostProcessor
• extends BeanFactoryPostProcessor
• void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry
registry)
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49. Cloud Support Plugin (cloud­foundry, heroku)
dataSourceBean.driverClassName =
updatedValues.driverClassName
dataSourceBean.url = updatedValues.url + suffix
dataSourceBean.username = updatedValues.userName
dataSourceBean.password = updatedValues.password
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50. Alternate approach to BeanDefinition modification
def doWithSpring = {
def mybeanDef = delegate.getBeanDefinition('mybean')
mybeanDef.beanClass = NewClass
mybeanDef.propertyValues.add("order",
application.config.plugin?.rendering?.order ?: 42)
}
● Use loadAfter = ['plugin1', 'plugin2'] to
ensure the bean is loaded
● Only valid in a plugin, not the app's resources.groovy
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51. Bean Aliases
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52. Aliases
 As of Grails 2.1 aliases work fully
• You can create aliases pre­2.1 but only if defined in the same
resources.groovy or plugin (doWithSpring)
beans = {
springConfig.addAlias 'alias', 'realBean'
}
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53. Aliases
 The cache plugin registers the alias cacheOperationSource for
the bean registered as
org.springframework.cache.annotation.AnnotationCacheOperationSource#0
 Can use to have multiple implementations of a bean and choose
one via configuration at startup, e.g. per­environment or some
other rule
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54. Aliases
import grails.util.Environment
beans = {
String realBeanName
switch (Environment.current) {
case Environment.TEST:
realBeanName = 'testCardProcessingService'; break
case Environment.PRODUCTION:
realBeanName = 'productionCardProcessingService'; break
default: // Environment.DEVELOPMENT, custom envs
realBeanName = 'mockCardProcessingService'; break
}
springConfig.addAlias 'cardProcessingService', realBeanName
}
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55. Internationalization
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56. Internationalization
 First­class support in Grails via .properties files in grails­app/i18n
 All generated controllers, GSPs, and layouts are fully
internationalized with no hard­coded strings
 Domain class validation errors are internationalized the same way
 Enabled under the hood by the messageSource bean
(org.springframework.context.MessageSource)
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57. Internationalization
 Use the <g:message> tag in GSPs, message method in
controllers
 Or use dependency injection like with any Spring bean
• def messageSource
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58. Spring MVC Controllers
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59. Spring MVC
 New in Grails 1.2
 Annotate src/java or src/groovy classes with @Controller
 Add all packages to the grails.spring.bean.packages list in
Config.groovy
• e.g.grails.spring.bean.packages = ['gr8conf.testapp.foo']
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60. Spring MVC
 Annotate methods with
@o.s.w.bind.annotation.RequestMapping
@RequestMapping("/mvc/hello.dispatch")
public ModelMap handleRequest() {
return new ModelMap()
.addAttribute("text", "some text")
.addAttribute("cost", 42)
.addAttribute("config",
grailsApplication.getConfig().flatten()));
}
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61. Spring MVC
 @RequestMapping URI value must end in .dispatch
 Add entries in UrlMappings to create more natural URLs
class UrlMappings {
static mappings = {
…
"/mvc/hello"(uri:"/mvc/hello.dispatch")
"/mvc/other"(uri:"/mvc/other.dispatch")
}
}
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62. Spring MVC
 Use @Autowired for dependency injection (on fields in Groovy
classes, on setters or constructors in Java)
private GrailsApplication grailsApplication;
@Autowired
public void setGrailsApplication(GrailsApplication app) {
grailsApplication = app;
}
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63. Hibernate Integration
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64. Hibernate Integration
 org.springframework.orm.hibernate3.
LocalSessionFactoryBean factory bean configures
org.hibernate.SessionFactory instances
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65. Hibernate Integration
 org.springframework.orm.hibernate3.
HibernateTransactionManager implements
org.springframework.transaction.
PlatformTransactionManager to abstract away the details of
transaction management
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66. Thread­local holders
 Cumbersome to explicitly open a Hibernate Session or start a
transaction and have to pass one or more related objects from
method to method
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67. Thread­local holders
 Spring uses ThreadLocal scope since web requests are handled
per-thread
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68. Thread­local holders
 See org.springframework.transaction.support.
TransactionSynchronizationManager and
org.springframework.orm.hibernate3.
SessionFactoryUtils helper classes
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69. Thread­local holders
 Further helped by
org.codehaus.groovy.grails.orm.hibernate.support.
GrailsOpenSessionInViewInterceptor
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70. Thread­local holders
 Opens a Hibernate Session at the start of all controller requests
and registers it in thread-local scope
 For the duration of the request, there is always an active session
 After the request it flushes and closes the Session
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71. Thread­local holders
 Hibernate implementation of GORM uses a
org.springframework.orm.hibernate3.
HibernateTemplate under the hood to execute most queries
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72. Thread­local holders
 HibernateTemplate uses SessionFactoryUtils.getSession() to
find or create a Session
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73. Thread­local holders
 Plugins that enable asynchronous processing (Quartz, Gpars,
Executor) all implement patterns similar to OpenSessionInView
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74. Other Cool Stuff
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75. Other Cool Stuff
 Standard and Custom Events
 Resources
 Data Binding and Validation
 Marshalling XML using O/X Mappers
 JMS (see Grails jms and ActiveMQ plugins)
 EJBs
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76. Other Cool Stuff
 Remoting (see the Grails remoting plugin)
• Remote Method Invocation (RMI)
• Hessian (Caucho's lightweight binary HTTP­based protocol)
• Burlap (another protocol from Caucho which uses XML)
• Spring's HTTP invoker
 JMX (see the Grails jmx plugin)
 Email (see the Grails mail plugin)
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77. Other Cool Stuff
 Other persistence support
• HibernateTemplate
• JdbcTemplate
• Other database support
• JDO
• JPA
• iBATIS (2.x) SQL Maps
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78. Want More Information?
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80. Thank You
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