Spring JPA transaction over multiple methods

Question

I'm using Spring 3.2 with JPA and Hibernate 4 in a web application running in Tomcat 7. The application is divided into controller, service an DAO classes. The service classes have an annotated transaction configuration at class and method level. The DAOs are plain JPA with entity manager injected by @PersistenceContext annotation.

@Service("galleryService")
@Transactional(propagation=Propagation.SUPPORTS, readOnly=true)
public class GalleryServiceImpl implements GalleryService {

  @Override
  public Picture getPicture(Long pictureId) {
    return pictureDao.find(pictureId);
  }

  @Override
  public List<PictureComment> getComments(Picture picture) {
    List<PictureComment> comments = commentDao.findVisibleByPicture(picture);
    Collections.sort(comments, new Comment.ByCreatedOnComparator(Comment.ByCreatedOnComparator.SORT_DESCENDING));
    return comments;
  }
  ...
}

@Controller
@RequestMapping("/gallery/displayPicture.html")
public class DisplayPictureController extends AbstractGalleryController {

  @RequestMapping(method = RequestMethod.GET)
  public String doGet(ModelMap model, @RequestParam(REQUEST_PARAM_PICTURE_ID) Long pictureId) {
    Picture picture = galleryService.getPicture(pictureId);
    if (picture != null) {
      model.addAttribute("picture", picture);
      // Add comments
      model.addAttribute("comments", galleryService.getComments(picture));
    } else {
      LOGGER.warn(MessageFormat.format("Picture {0} not found.", pictureId));
      return ViewConstants.CONTENT_NOT_FOUND;
    }
    return ViewConstants.GALLERY_DISPLAY_PICTURE;
  }
  ...
}

I switched on debug logging for org.springframework.transaction and noticed, that "Creating new transaction", "Opened new EntityManager", "Getting...", "Closing..." and "Committing transaction" is done for every call of a method in my service class. Even if those methods where called by one single method in my controller class. Here is an example of my log output:

2014-12-03 10:53:00,448 org.springframework.transaction.support.AbstractPlatformTransactionManager getTransaction
DEBUG: Creating new transaction with name [de.domain.webapp.gallery.service.GalleryServiceImpl.getPicture]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT,readOnly
2014-12-03 10:53:00,448 org.springframework.orm.jpa.JpaTransactionManager doBegin
DEBUG: Opened new EntityManager [org.hibernate.jpa.internal.EntityManagerImpl@6133a72f] for JPA transaction
2014-12-03 10:53:00,468 org.springframework.orm.jpa.JpaTransactionManager doBegin
DEBUG: Exposing JPA transaction as JDBC transaction [org.springframework.orm.jpa.vendor.HibernateJpaDialect$HibernateConnectionHandle@5182c1b7]
2014-12-03 10:53:00,468 org.springframework.transaction.interceptor.TransactionAspectSupport prepareTransactionInfo
TRACE: Getting transaction for [de.domain.webapp.gallery.service.GalleryServiceImpl.getPicture]
2014-12-03 10:53:00,489 org.springframework.transaction.interceptor.TransactionAspectSupport commitTransactionAfterReturning
TRACE: Completing transaction for [de.domain.webapp.gallery.service.GalleryServiceImpl.getPicture]
2014-12-03 10:53:00,489 org.springframework.transaction.support.AbstractPlatformTransactionManager processCommit
DEBUG: Initiating transaction commit
2014-12-03 10:53:00,489 org.springframework.orm.jpa.JpaTransactionManager doCommit
DEBUG: Committing JPA transaction on EntityManager [org.hibernate.jpa.internal.EntityManagerImpl@6133a72f]
2014-12-03 10:53:00,489 org.springframework.orm.jpa.JpaTransactionManager doCleanupAfterCompletion
DEBUG: Closing JPA EntityManager [org.hibernate.jpa.internal.EntityManagerImpl@6133a72f] after transaction
2014-12-03 10:53:00,489 org.springframework.orm.jpa.EntityManagerFactoryUtils closeEntityManager
DEBUG: Closing JPA EntityManager

I know that I can use an OpenSessionInView to hold the hibernate session for a complete request but some people said, OSIV is an antipattern. Instead I'm using SpringOpenEntityManagerInViewFilter. But with no success. How can I achieve, Spring uses a single transaction for multiple service layer method calls of my controller? Or did I missunderstand anything?

Here a part of my Spring configuration:

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
            <property name="database" value="MYSQL" />
            <property name="showSql" value="false" />
        </bean>
    </property>
</bean>

<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
    <property name="jndiName" value="java:comp/env/jdbc/tikron" />
</bean>

<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

<bean id="jpaTemplate" class="org.springframework.orm.jpa.JpaTemplate">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

<tx:annotation-driven transaction-manager="transactionManager" />

<context:component-scan base-package="de.domain.webapp">
    <context:include-filter type="regex" expression=".*Service"/>
</context:component-scan>

My persistence unit:

<persistence-unit name="tikron-data" transaction-type="RESOURCE_LOCAL">
  <!-- Entities located in external project tikron-data -->
  <jar-file>/WEB-INF/lib/tikron-data-2.0.1-SNAPSHOT.jar</jar-file>
  <!-- Enable JPA 2 second level cache -->
  <shared-cache-mode>ALL</shared-cache-mode>
  <properties>
    <property name="hibernate.hbm2ddl.auto" value="validate" />
    <property name="hibernate.cache.use_second_level_cache" value="true" />
    <property name="hibernate.cache.use_query_cache" value="true" />
    <property name="hibernate.cache.region.factory_class" value="org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory"/>
    <property name="hibernate.generate_statistics" value="false" /> 
  </properties>
</persistence-unit>

Some more log output from application startup:

2014-12-03 10:46:48,428 org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean createNativeEntityManagerFactory
INFO: Building JPA container EntityManagerFactory for persistence unit 'tikron-data'
2014-12-03 10:46:48,428 org.hibernate.ejb.HibernatePersistence logDeprecation
WARN: HHH015016: Encountered a deprecated javax.persistence.spi.PersistenceProvider [org.hibernate.ejb.HibernatePersistence]; use [org.hibernate.jpa.HibernatePersistenceProvider] instead.
2014-12-03 10:46:48,448 org.hibernate.jpa.internal.util.LogHelper logPersistenceUnitInformation
INFO: HHH000204: Processing PersistenceUnitInfo [
    name: tikron-data
    ...]

...

2014-12-03 10:46:51,101 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@6cccf90d: defining beans [propertyConfigurer,messageSource,entityManagerFactory,dataSource]; root of factory hierarchy
2014-12-03 10:46:51,111 org.springframework.web.context.ContextLoader initWebApplicationContext
INFO: Root WebApplicationContext: initialization completed in 3374 ms

Thanks in advance.

Answer 1

You need to play your PROPAGATION_LEVEL and structure your service bean calls properly. If you're using @Transactional on your Service classes, what you described is normal, since the transaction demarcation happens on public methods level. So depending on the propagation level when entering the public method of the service bean, the transaction will either start, join an existing transaction, throw an exception or execute non-transactionally.

To have service methods execute in one transaction, its enough to have the propagation level set to support as you do in your GalleryService (providing that you don't override it on a method level), and call these methods from a single method of another service which is annotated @Transactional(propagation=Propagation.REQUIRED). Its important to have you're calls pass through a bean e.g. (galleryService.getPicture instead of local call getPicture), 'cause aspects that inject the transaction semantics work against a proxy that wraps the bean

@Service("exampleService")
@Transactional(propagation=Propagation.REQUIRED)
public class ExampleServiceImpl implements ExampleService {

  @Autowired
  private GalleryService galleryService;

  @Override
  public void singleTransaction() {
    galleryService.getPicture
    galleryService.getComments
  }

  ...
}

a brief PROPAGATION_LEVEL glossary

MANDATORY
          Support a current transaction, throw an exception if none exists.
NESTED
          Execute within a nested transaction if a current transaction exists, behave like PROPAGATION_REQUIRED else.
NEVER
          Execute non-transactionally, throw an exception if a transaction exists.
NOT_SUPPORTED
          Execute non-transactionally, suspend the current transaction if one exists.
REQUIRED
          Support a current transaction, create a new one if none exists.
REQUIRES_NEW
          Create a new transaction, suspend the current transaction if one exists.
SUPPORTS
          Support a current transaction, execute non-transactionally if none exists.

UPDATE with respect to the comment

But is combining service method calls into one service method the only way to handle those calls in one single transaction?

No, but in my opinion its your best option. Consider the article http://www.ibm.com/developerworks/java/library/j-ts2/index.html. What I'm describing is whats referred to in the article as API layer strategy. Its defined as

The API Layer transaction strategy is used when you have coarse-grained methods that act as primary entry points to back-end functionality. (Call them services if you would like.) In this scenario, clients (be they Web-based, Web services based, message-based, or even desktop) make a single call to the back end to perform a particular request.

Now in the standard three-layer architecture you have the presentation, a business and a persistence layer. In simple words you can annotate your controllers, services or DAOs. Services are the ones holding the logical unit of work. If you annotate your controllers, they are part of your presentation layer, if your transactional semantics is there, and you decide to switch or add a non-http client (e.g. Swing client), you're bound to either migrate or duplicate your transaction logic. DAO layers should also not be the owners of transaction, 'the granularity of the DAO methods is much less than what is a business logical unit. I'm restraining from points like best-practice etc. but, if you're uncertain, choose your business (service) as your API transaction layer :)

You have numerous posts discussing this topic in all directions

why use @transactional with @service insted of with @controller Where should "@Transactional" be place Service Layer or DAO

very good and fun reading, many opinions and very context-dependant