Handle spring-data-rest application events within

问题:

I need to publish notification events to external systems over JMS, when data is updated. Id like this to be done within the same transaction as the objects are committed to the database to ensure integrity.

The ApplicationLifecycle events that spring-data-rest emits seemed like the logical place to implement this logic.

@org.springframework.transaction.annotation.Transactional
public class TestEventListener extends AbstractRepositoryEventListener<Object> {

    private static final Logger LOG = LoggerFactory.getLogger(TestEventListener.class);

    @Override
    protected void onBeforeCreate(Object entity) {
        LOG.info("XXX before create");
    }

    @Override
    protected void onBeforeSave(Object entity) {
        LOG.info("XXX before save");
    }

    @Override
    protected void onAfterCreate(Object entity) {
        LOG.info("XXX after create");
    }

    @Override
    protected void onAfterSave(Object entity) {
        LOG.info("XXX after save");
    }

}

However, these events happen before and after the tx starts and commits.

08 15:32:37.119 [http-nio-9000-exec-1] INFO  n.c.v.vcidb.TestEventListener - XXX before create 
08 15:32:37.135 [http-nio-9000-exec-1] TRACE o.s.t.i.TransactionInterceptor - Getting transaction for [org.springframework.data.jpa.repository.support.SimpleJpaRepository.save]



08 15:32:37.432 [http-nio-9000-exec-1] TRACE o.s.t.i.TransactionInterceptor - Completing transaction for [org.springframework.data.jpa.repository.support.SimpleJpaRepository.save] 
08 15:32:37.479 [http-nio-9000-exec-1] INFO  n.c.v.vcidb.TestEventListener - XXX after create 

What extension point does spring-data-rest have for adding behaviour that will execute within the spring managed transaction?

回答1:

I use aop (pointcut and tx advice) to solve this problem:

@Configuration
@ImportResource("classpath:/aop-config.xml")
public class AopConfig { ...

and aop-config.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans   http://www.springframework.org/schema/beans/spring-beans.xsd
                      http://www.springframework.org/schema/aop     http://www.springframework.org/schema/aop/spring-aop.xsd
                      http://www.springframework.org/schema/tx      http://www.springframework.org/schema/tx/spring-tx.xsd"
    default-autowire="byName">

    <aop:config>
        <aop:pointcut id="restRepositoryTx"
            expression="execution(* org.springframework.data.rest.webmvc.RepositoryEntityController.*(..))" />
        <aop:advisor id="managerTx" advice-ref="txAdvice" pointcut-ref="restRepositoryTx" order="20" />
    </aop:config>

    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="postCollectionResource*" propagation="REQUIRES_NEW" rollback-for="Exception" />
            <tx:method name="putItemResource*" propagation="REQUIRES_NEW" rollback-for="Exception" />
            <tx:method name="patchItemResource*" propagation="REQUIRES_NEW" rollback-for="Exception" />
            <tx:method name="deleteItemResource*" propagation="REQUIRES_NEW" rollback-for="Exception" />
            <!-- <tx:method name="*" rollback-for="Exception" /> -->
        </tx:attributes>
    </tx:advice>

</beans>

This is the same as having controller methods annotated with @Transactional.

回答2:

The solution described by phlebas work. And I also think "Run event handler within a same transaction" should be a feature which should be provided by Spring Data Rest. There are many common use cases to need to split logic to sepreate eventHandler. just like "triggers in database". The version show below is same as phlebas solution.

    @Aspect
    @Component
    public class SpringDataRestTransactionAspect {

        private TransactionTemplate transactionTemplate;

        public SpringDataRestTransactionAspect(PlatformTransactionManager transactionManager) {
            this.transactionTemplate = new TransactionTemplate(transactionManager);
            this.transactionTemplate.setName("around-data-rest-transaction");
        }

        @Pointcut("execution(* org.springframework.data.rest.webmvc.*Controller.*(..))")
        public void aroundDataRestCall(){}

        @Around("aroundDataRestCall()")
        public Object aroundDataRestCall(ProceedingJoinPoint joinPoint) throws Throwable {
            return transactionTemplate.execute(transactionStatus -> {
                try {
                    return joinPoint.proceed();
                } catch (Throwable e) {
                    transactionStatus.setRollbackOnly();
                    if(e instanceof RuntimeException) {
                        throw (RuntimeException)e;
                    } else {
                        throw new RuntimeException(e);
                    }
                }
            });
        }
    }

回答3:

I have not worked on spring-data-rest, but with spring, this can be handled the following way.

1) Define custom TransactionSynchronizationAdapter, and register the bean in TransactionSynchronizationManager.

Usually, I have a method registerSynchronizaiton with a @Before pointcut for this.

@SuppressWarnings("rawtypes") @Before("@annotation(org.springframework.transaction.annotation.Transactional)")
    public void registerSynchronization() {
        // TransactionStatus transStatus = TransactionAspectSupport.currentTransactionStatus();
        TransactionSynchronizationManager.registerSynchronization(this);
        final String transId = UUID.randomUUID().toString();
        TransactionSynchronizationManager.setCurrentTransactionName(transId);
        transactionIds.get().push(transId);
        if (TransactionSynchronizationManager.isActualTransactionActive() && TransactionSynchronizationManager
            .isSynchronizationActive() && !TransactionSynchronizationManager.isCurrentTransactionReadOnly()) {
            if (!TransactionSynchronizationManager.hasResource(KEY)) {
                final List<NotificationPayload> notifications = new ArrayList<NotificationPayload>();
                TransactionSynchronizationManager.bindResource(KEY, notifications);
            }
        }
    }

2) And, implement Override method as follows

@Override public void afterCompletion(final int status) {
    CurrentContext context = null;
    try {
        context = ExecutionContext.get().getContext();
    } catch (final ContextNotFoundException ex) {
        logger.debug("Current Context is not available");
        return;
    }
    if (status == STATUS_COMMITTED) {
        transactionIds.get().removeAllElements();
        publishedEventStorage.sendAllStoredNotifications();
        // customize here for commit actions
    } else if ((status == STATUS_ROLLED_BACK) || (status == STATUS_UNKNOWN)) {
       // you can write your code for rollback actions
    }
}