EJB3 (JBoss 5) Problem with Persistence Context / Transaction

[Marcus Didius Falco]

I am experimentig with JPA and I have difficulties to reproduce an example taken from JavaMagazin 9/09 about the ECB Pattern.
JBoss 5.1.0 GA, MySQL 5.0



The "boundary" (facade)

   
@Stateless
public class OrderServiceBean implements OrderService {

	
	
	@EJB
	DeliveryService deliveryService;
	
	@EJB
	Warehouse warehouse;
	
	@TransactionAttribute(TransactionAttributeType.REQUIRED)
	public Order order(Order newOrder) throws BillingException {
		
		Order order = warehouse.checkout(newOrder);
		
		
		deliveryService.deliver(order);
		return order;
	}
}

 

The Warehouse Bean persists the order. This works like expected:

   
@Stateless
public class WarehouseBean implements Warehouse {

	@PersistenceContext(unitName="ECB")
	EntityManager entityManager;
	
	@TransactionAttribute(TransactionAttributeType.MANDATORY)
	public Order checkout(Order order) {
		this.entityManager.merge(order);
		return order;
	}
}	

 

However the DeliveryService modifies the order:

   
@Stateless
public class DeliveryServiceBean implements DeliveryService{

	@TransactionAttribute(TransactionAttributeType.MANDATORY)
	public void deliver(Order order) {
		order.setDelivered(true);
		order.setProductId(2);
	}
}	
 

Since the transaction should be still running, I expect that order is still in the persistence context and that the changes made by the DeliveryService should be automatically persisted. However they never arrive in the database.

Do I get the whole concept or persistence context wrong? Or is there some bug in my code?

    
<?xml version="1.0" encoding="UTF-8"?>

<!-- $Id: mysql-ds.xml 71535 2008-04-01 07:05:03Z [e-mail] $ -->
<!--  Datasource config for MySQL using 3.0.9 available from:
http://www.mysql.com/downloads/api-jdbc-stable.html
-->

<datasources>
  <local-tx-datasource>
    <jndi-name>ECBDS</jndi-name>
    <connection-url>jdbc:mysql://localhost:3306/ecb</connection-url>
    <driver-class>com.mysql.jdbc.Driver</driver-class>
    <user-name>root</user-name>
    <password>ritak1</password>
    <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</exception-sorter-class-name>
    <!-- should only be used on drivers after 3.22.1 with "ping" support
    <valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLValidConnectionChecker</valid-connection-checker-class-name>
    -->
    <!-- sql to call when connection is created
    <new-connection-sql>some arbitrary sql</new-connection-sql>
      -->
    <!-- sql to call on an existing pooled connection when it is obtained from pool - MySQLValidConnectio
nChecker is preferred for newer drivers
    <check-valid-connection-sql>some arbitrary sql</check-valid-connection-sql>
      -->

    <!-- corresponding type-mapping in the standardjbosscmp-jdbc.xml (optional) -->
    <metadata>
       <type-mapping>mySQL</type-mapping>
    </metadata>
  </local-tx-datasource>
</datasources>
	

    
<?xml version="1.0" encoding="UTF-8"?>
<persistence:persistence version="1.0"
 xmlns:persistence="http://java.sun.com/xml/ns/persistence"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence persistence_1_0.xsd">
	<persistence:persistence-unit name="ECB">
		<persistence:description>ECB</persistence:description>
		<persistence:jta-data-source>java:ECBDS</persistence:jta-data-source>
		<persistence:properties>
			<persistence:property name="hibernate.hbm2ddl.auto" value="create-drop" />
			<persistence:property name="dialect" value="org.hibernate.dialect.MySQLDialect" />
			<persistence:property name="hibernate.show_sql" value="true" />
			<persistence:property name="hibernate.format_sql" value="true" />
		</persistence:properties>
	</persistence:persistence-unit>
</persistence:persistence>

[Christian Gossart]

Hi Marcus,

Seems the checkout method is bugged if you are using it with a brand new Order instance: when using the merge method of the EntityManager with a new entity instance, this instance remained detached while a new managed instance is created and stored in the persistence context. It is this managed instance that is returned from the merge call. To get a hold on it, use the following code instead:

 
    @TransactionAttribute(TransactionAttributeType.MANDATORY)   
    public Order checkout(Order order) {   
        return this.entityManager.merge(order);   
        //return order;
    } 

Then the Order instance returned from the checkout method is managed, and any change done by the deliver method will produce an sql update when the transaction commits.