Persistence Context Transaction

[marcusdidiusfalco]

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 - MySQLValidConnectionChecker 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>

[marcusdidiusfalco]

I found the bug:

The checkout method must return the order returned by the entity manager.

@Stateless
public class WarehouseBean implements Warehouse {

 @PersistenceContext(unitName="ECB")
 EntityManager entityManager;

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